No association between partial depopulation and Campylobacter spp. colonization of Dutch broiler flocks.

PubMed

Russa, A D; Bouma, A; Vernooij, J C M; Jacobs-Reitsma, W; Stegeman, J A

2005-01-01

To determine whether an association exists between partial depopulation of a flock and increased Campylobacter colonization in that flock. Data from 1737 flocks of two Dutch integrators were used. Flocks that experienced partial depopulation were defined as 'exposed' and those that did not as 'nonexposed'. Multivariable modelling was accomplished with, in addition to 'exposure', the independent variables 'age of broilers at slaughter' and 'season' to adjust for possible confounding. The response variable was 'Campylobacter colonization'. The odds ratio (OR) for partial depopulation for integrator A was 0.8 [95% CI (0.4, 1.8)]; for integrator B the OR = 0.8 [95% CI (0.5, 1.3)]. Age and season were confounders: the difference in Campylobacter status between exposed and nonexposed flocks of integrator A could be explained by both variables; for integrator B, only season was associated with Campylobacter status. We found no significant association between partial depopulation and an increased risk of Campylobacter colonization among broiler flocks at final depopulation. This study demonstrates that Campylobacter colonization in a broiler flock is not influenced by the partial depopulation of that flock.

Mismeasurement and the resonance of strong confounders: uncorrelated errors.

PubMed

Marshall, J R; Hastrup, J L

1996-05-15

Greenland first documented (Am J Epidemiol 1980; 112:564-9) that error in the measurement of a confounder could resonate--that it could bias estimates of other study variables, and that the bias could persist even with statistical adjustment for the confounder as measured. An important question is raised by this finding: can such bias be more than trivial within the bounds of realistic data configurations? The authors examine several situations involving dichotomous and continuous data in which a confounder and a null variable are measured with error, and they assess the extent of resultant bias in estimates of the effect of the null variable. They show that, with continuous variables, measurement error amounting to 40% of observed variance in the confounder could cause the observed impact of the null study variable to appear to alter risk by as much as 30%. Similarly, they show, with dichotomous independent variables, that 15% measurement error in the form of misclassification could lead the null study variable to appear to alter risk by as much as 50%. Such bias would result only from strong confounding. Measurement error would obscure the evidence that strong confounding is a likely problem. These results support the need for every epidemiologic inquiry to include evaluations of measurement error in each variable considered.

The ACCE method: an approach for obtaining quantitative or qualitative estimates of residual confounding that includes unmeasured confounding

PubMed Central

Smith, Eric G.

2015-01-01

Background:  Nonrandomized studies typically cannot account for confounding from unmeasured factors.  Method:  A method is presented that exploits the recently-identified phenomenon of  “confounding amplification” to produce, in principle, a quantitative estimate of total residual confounding resulting from both measured and unmeasured factors.  Two nested propensity score models are constructed that differ only in the deliberate introduction of an additional variable(s) that substantially predicts treatment exposure.  Residual confounding is then estimated by dividing the change in treatment effect estimate between models by the degree of confounding amplification estimated to occur, adjusting for any association between the additional variable(s) and outcome. Results:  Several hypothetical examples are provided to illustrate how the method produces a quantitative estimate of residual confounding if the method’s requirements and assumptions are met.  Previously published data is used to illustrate that, whether or not the method routinely provides precise quantitative estimates of residual confounding, the method appears to produce a valuable qualitative estimate of the likely direction and general size of residual confounding. Limitations:  Uncertainties exist, including identifying the best approaches for: 1) predicting the amount of confounding amplification, 2) minimizing changes between the nested models unrelated to confounding amplification, 3) adjusting for the association of the introduced variable(s) with outcome, and 4) deriving confidence intervals for the method’s estimates (although bootstrapping is one plausible approach). Conclusions:  To this author’s knowledge, it has not been previously suggested that the phenomenon of confounding amplification, if such amplification is as predictable as suggested by a recent simulation, provides a logical basis for estimating total residual confounding. The method's basic approach is straightforward.  The method's routine usefulness, however, has not yet been established, nor has the method been fully validated. Rapid further investigation of this novel method is clearly indicated, given the potential value of its quantitative or qualitative output. PMID:25580226

Risk factors for recurrent gastroesophageal reflux disease after fundoplication in pediatric patients: a case-control study.

PubMed

Ngerncham, Monawat; Barnhart, Douglas C; Haricharan, Ramanath N; Roseman, Jeffrey M; Georgeson, Keith E; Harmon, Carroll M

2007-09-01

Recurrent gastroesophageal reflux disease (rGERD) is a common problem after fundoplication. Previous studies attempting to identify risk factors for rGERD have failed to control for confounding variables. The purpose of this study was to identify significant risk factors for rGERD after controlling for potential confounding variables. A retrospective, matched case-control study was conducted at a tertiary children's hospital. Cases (n = 116) met 1 of these criteria: reoperation for rGERD, symptomatic rGERD (confirmed by upper gastrointestinal series, esophagogastroduodenoscopy, or pH monitoring), or postoperative reinstitution of antireflux medication for more than 8 weeks. Controls (n = 209) were matched for surgeon, approach (laparoscopic/open), technique (partial/complete), and approximate operative date. Univariate and multivariable associations were analyzed by conditional logistic regression. Significant risk factors for rGERD were age of less than 6 years (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.7-7.5), preoperative hiatal hernia (OR, 3.2; 95% CI, 1.4-7.3), postoperative retching (OR, 5.1; 95% CI, 2.6-10.0), and postoperative esophageal dilatation (OR, 10.8; 95% CI, 1.8-65.4). Interestingly, significant association was not found between neurologic impairment and rGERD after controlling for potential confounding variables. Age of less than 6 years, preoperative hiatal hernia, postoperative retching, and postoperative esophageal dilatation are independently associated with increased risk of rGERD. Neurologic impairment alone does not increase the risk of developing rGERD.

Alcohol Use in Adolescence and Later Working Memory: Findings From a Large Population-Based Birth Cohort

PubMed Central

Field, Matt; Gage, Suzanne; Hammerton, Gemma; Heron, Jon; Hickman, Matt; Munafò, Marcus R

2018-01-01

Abstract Aims The study aimed to examine the association between adolescent alcohol use and working memory (WM) using a large population sample. Methods Data from the Avon Longitudinal Study of Parents and Children were used to investigate the association between alcohol use at age 15 years and WM 3 years later, assessed using the N-back task (N ~ 3300). A three-category ordinal variable captured mutually exclusive alcohol groupings ranging in order of severity (i.e. low alcohol users, frequent drinkers and frequent/binge drinkers). Differential dropout was accounted for using multiple imputation and inverse probability weighting. Adjustment was made for potential confounders. Results There was evidence of an association between frequent/binge drinking (compared to the low alcohol group) and poorer performance on the 3-back task after adjusting for sociodemographic confounding variables, WM at age 11 years, and experience of a head injury/unconsciousness before age 11 years (β = −0.23, 95% CI = −0.37 to −0.09, P = 0.001). However, this association was attenuated (β = −0.12, 95% CI = −0.27 to 0.03, P = 0.11) when further adjusted for baseline measures of weekly cigarette tobacco and cannabis use. Weaker associations were found for the less demanding 2-back task. We found no evidence to suggest frequent drinking was associated with performance on either task. Conclusions We found weak evidence of an association between sustained heavy alcohol use in mid-adolescence and impaired WM 3 years later. Although we cannot fully rule out the possibility of reverse causation, several potential confounding variables were included to address the directionality of the relationship between WM and alcohol use problems. PMID:29329371

Alcohol Use in Adolescence and Later Working Memory: Findings From a Large Population-Based Birth Cohort.

PubMed

Mahedy, Liam; Field, Matt; Gage, Suzanne; Hammerton, Gemma; Heron, Jon; Hickman, Matt; Munafò, Marcus R

2018-05-01

The study aimed to examine the association between adolescent alcohol use and working memory (WM) using a large population sample. Data from the Avon Longitudinal Study of Parents and Children were used to investigate the association between alcohol use at age 15 years and WM 3 years later, assessed using the N-back task (N ~ 3300). A three-category ordinal variable captured mutually exclusive alcohol groupings ranging in order of severity (i.e. low alcohol users, frequent drinkers and frequent/binge drinkers). Differential dropout was accounted for using multiple imputation and inverse probability weighting. Adjustment was made for potential confounders. There was evidence of an association between frequent/binge drinking (compared to the low alcohol group) and poorer performance on the 3-back task after adjusting for sociodemographic confounding variables, WM at age 11 years, and experience of a head injury/unconsciousness before age 11 years (β = -0.23, 95% CI = -0.37 to -0.09, P = 0.001). However, this association was attenuated (β = -0.12, 95% CI = -0.27 to 0.03, P = 0.11) when further adjusted for baseline measures of weekly cigarette tobacco and cannabis use. Weaker associations were found for the less demanding 2-back task. We found no evidence to suggest frequent drinking was associated with performance on either task. We found weak evidence of an association between sustained heavy alcohol use in mid-adolescence and impaired WM 3 years later. Although we cannot fully rule out the possibility of reverse causation, several potential confounding variables were included to address the directionality of the relationship between WM and alcohol use problems.

Gardening and age-related weight gain: Results from a cross-sectional survey of Denver residents.

PubMed

Litt, Jill S; Lambert, Jeffrey Richard; Glueck, Deborah H

2017-12-01

This study examined whether gardening modifies the association between age and body mass index (BMI). We used data from the Neighborhood Environments and Health Survey, which was conducted in Denver (N = 469) between 2006 and 2007. We fit two general linear mixed models. The base model had BMI in kg/m 2 as the outcome, and age, an indicator variable for non-gardening status and the age-by-non-gardening status interaction as predictors. The adjusted model included as covariates the potential confounders of education, ethnicity and self-reported health. We assessed self-selection bias and confounding. BMI was 27.18 kg/m 2 for non-gardeners, 25.62 kg/m 2 for home gardeners, and 24.17 kg/m 2 for community gardeners. In the base model, a statistically significant association was observed between age and BMI for non-gardeners but not for the combined community and home gardening group (F = 9.27, ndf = 1, ddf = 441, p = 0.0025). In the adjusted model, the association between age and BMI in non-gardeners was not statistically significant (F = 1.72, ndf = 1, ddf = 431, p = 0.1908). Gardeners differed on social and demographic factors when compared to non-gardeners. The results from the base model are consistent with the hypothesis that gardening might offset age-related weight gain. However, the cross-sectional design does not permit differentiation of true causal effects from the possible effects of bias and confounding. As a follow-up study, to remove bias and confounding, we are conducting a randomized clinical trial of community gardening in Denver.

Thyroid disorders in older adults.

PubMed

Visser, W Edward; Visser, Theo J; Peeters, Robin P

2013-06-01

This article summarizes the current literature about serum thyroid parameters and thyroid disease during aging. Changes in thyroid function tests may be part of the physiology of aging, after exclusion of confounding variables. Overt thyroid disease requires immediate treatment. Treatment of subclinical hyperthyroidism in the elderly can be advocated, while watchful waiting may be an appropriate approach for subclinical hypothyroidism. Copyright © 2013 Elsevier Inc. All rights reserved.

The relationship of bone and blood lead to hypertension: Further analyses of the normative aging study data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, H.; Kim, Rokho; Korrick, S.

1996-12-31

In an earlier report based on participants in the Veterans Administration Normative Aging Study, we found a significant association between the risk of hypertension and lead levels in tibia. To examine the possible confounding effects of education and occupation, we considered in this study five levels of education and three levels of occupation as independent variables in the statistical model. Of 1,171 active subjects seen between August 1991 and December 1994, 563 provided complete data for this analysis. In the initial logistic regression model, acre and body mass index, family history of hypertension, and dietary sodium intake, but neither cumulativemore » smoking nor alcohol ingestion, conferred increased odds ratios for being hypertensive that were statistically significant. When the lead biomarkers were added separately to this initial logistic model, tibia lead and patella lead levels were associated with significantly elevated odds ratios for hypertension. In the final backward elimination logistic regression model that included categorical variables for education and occupation, the only variables retained were body mass index, family history of hypertension, and tibia lead level. We conclude that education and occupation variables were not confounding the association between the lead biomarkers and hypertension that we reported previously. 27 refs., 3 tabs.« less

Perceived Discrimination among African American Adolescents and Allostatic Load: A Longitudinal Analysis with Buffering Effects

PubMed Central

Brody, Gene H.; Lei, Man-Kit; Chae, David H.; Yu, Tianyi; Kogan, Steven M.; Beach, Steven R. H.

2013-01-01

This study was designed to examine the prospective relations of perceived racial discrimination with allostatic load (AL), along with a possible buffer of the association. A sample of 331 African Americans in the rural South provided assessments of perceived discrimination from ages 16 to 18 years. When youths were 18, caregivers reported parental emotional support, and youths assessed peer emotional support. AL and potential confounder variables were assessed when youths were 20. Latent Growth Mixture Modeling identified two perceived discrimination classes: high and stable and low and increasing. Adolescents in the high and stable class evinced heightened AL even with confounder variables controlled. The racial discrimination to AL link was not significant for young adults who received high emotional support. PMID:24673162

What is the relationship between renal function and visit-to-visit blood pressure variability in primary care? Retrospective cohort study from routinely collected healthcare data.

PubMed

Lasserson, Daniel S; Scherpbier de Haan, Nynke; de Grauw, Wim; van der Wel, Mark; Wetzels, Jack F; O'Callaghan, Christopher A

2016-06-10

To determine the relationship between renal function and visit-to-visit blood pressure (BP) variability in a cohort of primary care patients. Retrospective cohort study from routinely collected healthcare data. Primary care in Nijmegen, the Netherlands, from 2007 to 2012. 19 175 patients who had a measure of renal function, and 7 separate visits with BP readings in the primary care record. Visit-to-visit variability in systolic BP, calculated from the first 7 office measurements, including SD, successive variation, absolute real variation and metrics of variability shown to be independent of mean. Multiple linear regression was used to analyse the influence of estimated glomerular filtration rate (eGFR) on BP variability measures with adjustment for age, sex, diabetes, mean BP, proteinuria, cardiovascular disease, time interval between measures and antihypertensive use. In the patient cohort, 57% were women, mean (SD) age was 65.5 (12.3) years, mean (SD) eGFR was 75.6 (18.0) mL/min/1.73m(2) and SD systolic BP 148.3 (21.4) mm Hg. All BP variability measures were negatively correlated with eGFR and positively correlated with age. However, multiple linear regressions demonstrated consistent, small magnitude negative relationships between eGFR and all measures of BP variability adjusting for confounding variables. Worsening renal function is associated with small increases in measures of visit-to-visit BP variability after adjustment for confounding factors. This is seen across the spectrum of renal function in the population, and provides a mechanism whereby chronic kidney disease may raise the risk of cardiovascular events. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Breath biomarkers for lung cancer detection and assessment of smoking related effects--confounding variables, influence of normalization and statistical algorithms.

PubMed

Kischkel, Sabine; Miekisch, Wolfram; Sawacki, Annika; Straker, Eva M; Trefz, Phillip; Amann, Anton; Schubert, Jochen K

2010-11-11

Up to now, none of the breath biomarkers or marker sets proposed for cancer recognition has reached clinical relevance. Possible reasons are the lack of standardized methods of sampling, analysis and data processing and effects of environmental contaminants. Concentration profiles of endogenous and exogenous breath markers were determined in exhaled breath of 31 lung cancer patients, 31 smokers and 31 healthy controls by means of SPME-GC-MS. Different correcting and normalization algorithms and a principal component analysis were applied to the data. Differences of exhalation profiles in cancer and non-cancer patients did not persist if physiology and confounding variables were taken into account. Smoking history, inspired substance concentrations, age and gender were recognized as the most important confounding variables. Normalization onto PCO2 or BSA or correction for inspired concentrations only partially solved the problem. In contrast, previous smoking behaviour could be recognized unequivocally. Exhaled substance concentrations may depend on a variety of parameters other than the disease under investigation. Normalization and correcting parameters have to be chosen with care as compensating effects may be different from one substance to the other. Only well-founded biomarker identification, normalization and data processing will provide clinically relevant information from breath analysis. 2010 Elsevier B.V. All rights reserved.

Bias, Confounding, and Interaction: Lions and Tigers, and Bears, Oh My!

PubMed

Vetter, Thomas R; Mascha, Edward J

2017-09-01

Epidemiologists seek to make a valid inference about the causal effect between an exposure and a disease in a specific population, using representative sample data from a specific population. Clinical researchers likewise seek to make a valid inference about the association between an intervention and outcome(s) in a specific population, based upon their randomly collected, representative sample data. Both do so by using the available data about the sample variable to make a valid estimate about its corresponding or underlying, but unknown population parameter. Random error in an experiment can be due to the natural, periodic fluctuation or variation in the accuracy or precision of virtually any data sampling technique or health measurement tool or scale. In a clinical research study, random error can be due to not only innate human variability but also purely chance. Systematic error in an experiment arises from an innate flaw in the data sampling technique or measurement instrument. In the clinical research setting, systematic error is more commonly referred to as systematic bias. The most commonly encountered types of bias in anesthesia, perioperative, critical care, and pain medicine research include recall bias, observational bias (Hawthorne effect), attrition bias, misclassification or informational bias, and selection bias. A confounding variable is a factor associated with both the exposure of interest and the outcome of interest. A confounding variable (confounding factor or confounder) is a variable that correlates (positively or negatively) with both the exposure and outcome. Confounding is typically not an issue in a randomized trial because the randomized groups are sufficiently balanced on all potential confounding variables, both observed and nonobserved. However, confounding can be a major problem with any observational (nonrandomized) study. Ignoring confounding in an observational study will often result in a "distorted" or incorrect estimate of the association or treatment effect. Interaction among variables, also known as effect modification, exists when the effect of 1 explanatory variable on the outcome depends on the particular level or value of another explanatory variable. Bias and confounding are common potential explanations for statistically significant associations between exposure and outcome when the true relationship is noncausal. Understanding interactions is vital to proper interpretation of treatment effects. These complex concepts should be consistently and appropriately considered whenever one is not only designing but also analyzing and interpreting data from a randomized trial or observational study.

Assessing the independent contribution of maternal educational expectations to children's educational attainment in early adulthood: a propensity score matching analysis.

PubMed

Pingault, Jean Baptiste; Côté, Sylvana M; Petitclerc, Amélie; Vitaro, Frank; Tremblay, Richard E

2015-01-01

Parental educational expectations have been associated with children's educational attainment in a number of long-term longitudinal studies, but whether this relationship is causal has long been debated. The aims of this prospective study were twofold: 1) test whether low maternal educational expectations contributed to failure to graduate from high school; and 2) compare the results obtained using different strategies for accounting for confounding variables (i.e. multivariate regression and propensity score matching). The study sample included 1,279 participants from the Quebec Longitudinal Study of Kindergarten Children. Maternal educational expectations were assessed when the participants were aged 12 years. High school graduation—measuring educational attainment—was determined through the Quebec Ministry of Education when the participants were aged 22-23 years. Findings show that when using the most common statistical approach (i.e. multivariate regressions to adjust for a restricted set of potential confounders) the contribution of low maternal educational expectations to failure to graduate from high school was statistically significant. However, when using propensity score matching, the contribution of maternal expectations was reduced and remained statistically significant only for males. The results of this study are consistent with the possibility that the contribution of parental expectations to educational attainment is overestimated in the available literature. This may be explained by the use of a restricted range of potential confounding variables as well as the dearth of studies using appropriate statistical techniques and study designs in order to minimize confounding. Each of these techniques and designs, including propensity score matching, has its strengths and limitations: A more comprehensive understanding of the causal role of parental expectations will stem from a convergence of findings from studies using different techniques and designs.

The diurnal course of salivary alpha-amylase in nurses: an investigation of potential confounders and associations with stress.

PubMed

Wingenfeld, Katja; Schulz, Michael; Damkroeger, Annika; Philippsen, Christine; Rose, Matthias; Driessen, Martin

2010-09-01

In psychoneuroendocrinology research, salivary measures have become increasingly important. While several studies focus on determinants of salivary cortisol such as age, gender, and gynaecological variables, less research has focused on confounding variables of salivary alpha-amylase (sAA). In a large sample of nurses (N=215) we analyzed the impact of age, gender, intake of oral contraceptives, smoking, coffee consumption as well as psychological parameters, such as work stress and burnout, on basal diurnal sAA release. Saliva was collected at 07:00 h, 11:30 h, 17:30 h, and 20:00 h on a working day during early shift. Only gender could be identified to have an impact on sAA, with females having a more pronounced sAA increase over the course of the day. Whereas depression, anxiety, work stress and burnout were not associated with sAA, a small negative correlation between social difficulties, measured with the Chronic Stress Screening Scale, and sAA could be identified. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Case-control studies of the efficacy of cancer screening: overcoming bias from nonrandom patterns of screening.

PubMed

Weiss, Noel S; Dhillon, Preet K; Etzioni, Ruth

2004-07-01

A case-control study of the efficacy of cancer screening, like any other case-control study, must deal with potential confounding. There are 2 categories of confounding variables that pose special problems for studies of screening: (1) age and calendar time resulting from different temporal distributions of screening between cases and controls irrespective of whether the screening test leads to a reduction in mortality; and (2) the administration of other screening tests for the cancer in question when it is not clear whether the result of the other test had a bearing on the decision to order the test under study. We describe circumstances in which confounding from these sources can be dealt with satisfactorily by means of restriction or adjustment, and other circumstances in which it cannot. Copyright 2004 Lippincott Williams and Wilkins

Pregnant women with the sickle cell trait are not at increased risk for developing preeclampsia.

PubMed

Stamilio, David M; Sehdev, Harish M; Macones, George A

2003-01-01

The primary objective of this study was to determine whether having the sickle cell trait is independently associated with preeclampsia. We performed a retrospective cohort study of 1998 pregnant patients who either did or did not have the sickle cell trait. All patients were screened for the sickle trait using the "Sickledex" test. Data on neonatal and maternal outcome, including preeclampsia, and potential confounding variables were abstracted from medical records. Unadjusted, stratified, and multiple logistic regression analyses were used to identify interactions, and confounding between multiple variables and the association between sickle cell trait and preeclampsia. With an anticipated 6.5% rate of preeclampsia, and alpha = 0.05, this cohort study has 80% power to detect a relative risk (RR) of 2.3 for preeclampsia. Univariate analysis revealed that the two cohorts were similar with regard to primiparity, maternal age, chronic diseases, birth weight, and gestational age at delivery, but the sickle cell trait cohort was more likely to have gestational diabetes and had a higher mean body mass index (BMI). In the univariate analysis, the sickle cell trait cohort was not at increased risk for preeclampsia [unadjusted RR = 0.5, 95% CI (0.2-1.6)]. After controlling for potential confounding variables with logistic regression analysis, sickle trait was not independently associated with preeclampsia [adjusted RR = 0.5, 95% CI (0.2- 1.6)]. In contrast to prior work, these data suggest that the sickle cell trait is not an independent risk factor for preeclampsia or postpartum complications. In fact, the data are more consistent with the sickle trait being protective for developing preeclampsia.

Effect of conjugal bereavement on mortality of the bereaved spouse in participants of the Renfrew/Paisley Study

PubMed Central

Hart, Carole L; Hole, David J; Lawlor, Debbie A; Smith, George Davey; Lever, Tony F

2007-01-01

Objectives To investigate how loss of a spouse affects mortality risk in the bereaved partner. Design and setting Prospective cohort study in Renfrew and Paisley in Scotland. Participants 4395 married couples aged 45–64 years when the study was carried out between 1972 and 1976. Methods The date of bereavement for the bereaved spouse was the date of death of his or her spouse. Bereavement could occur at any time during the follow‐up period, so it was considered as a time‐dependent exposure variable and the Cox proportional hazards model for time‐dependent variables was used. The relative rate (RR) of mortality was calculated for bereaved versus non‐bereaved spouses and adjusted for confounding variables. Main outcome measures Causes of death to 31 March 2004. Results Bereaved participants were at higher risk than non‐bereaved participants of dying from any cause (RR 1.27; 95% CI 1.2 to 1.35). These risks remained but were attenuated after adjustment for confounding variables. There were raised RRs for bereaved participants dying of cardiovascular disease, coronary heart disease, stroke, all cancer, lung cancer, smoking‐related cancer, and accidents or violence. After adjustment for confounding variables, RRs remained higher for bereaved participants for all these causes except for mortality from lung cancer. There was no strong statistical evidence that the increased risks of death associated with bereavement changed with time after bereavement. Conclusions Conjugal bereavement, in addition to existing risk factors, is related to mortality risk for major causes of death. PMID:17435215

Confounding and Statistical Significance of Indirect Effects: Childhood Adversity, Education, Smoking, and Anxious and Depressive Symptomatology.

PubMed

Sheikh, Mashhood Ahmed

2017-01-01

The life course perspective, the risky families model, and stress-and-coping models provide the rationale for assessing the role of smoking as a mediator in the association between childhood adversity and anxious and depressive symptomatology (ADS) in adulthood. However, no previous study has assessed the independent mediating role of smoking in the association between childhood adversity and ADS in adulthood. Moreover, the importance of mediator-response confounding variables has rarely been demonstrated empirically in social and psychiatric epidemiology. The aim of this paper was to (i) assess the mediating role of smoking in adulthood in the association between childhood adversity and ADS in adulthood, and (ii) assess the change in estimates due to different mediator-response confounding factors (education, alcohol intake, and social support). The present analysis used data collected from 1994 to 2008 within the framework of the Tromsø Study ( N = 4,530), a representative prospective cohort study of men and women. Seven childhood adversities (low mother's education, low father's education, low financial conditions, exposure to passive smoke, psychological abuse, physical abuse, and substance abuse distress) were used to create a childhood adversity score. Smoking status was measured at a mean age of 54.7 years (Tromsø IV), and ADS in adulthood was measured at a mean age of 61.7 years (Tromsø V). Mediation analysis was used to assess the indirect effect and the proportion of mediated effect (%) of childhood adversity on ADS in adulthood via smoking in adulthood. The test-retest reliability of smoking was good (Kappa: 0.67, 95% CI: 0.63; 0.71) in this sample. Childhood adversity was associated with a 10% increased risk of smoking in adulthood (Relative risk: 1.10, 95% CI: 1.03; 1.18), and both childhood adversity and smoking in adulthood were associated with greater levels of ADS in adulthood ( p < 0.001). Smoking in adulthood did not significantly mediate the association between childhood adversity and ADS in adulthood. However, when education was excluded as a mediator-response confounding variable, the indirect effect of childhood adversity on ADS in adulthood was statistically significant ( p < 0.05). This study shows that a careful inclusion of potential confounding variables is important when assessing mediation.

Confounding and Statistical Significance of Indirect Effects: Childhood Adversity, Education, Smoking, and Anxious and Depressive Symptomatology

PubMed Central

Sheikh, Mashhood Ahmed

2017-01-01

The life course perspective, the risky families model, and stress-and-coping models provide the rationale for assessing the role of smoking as a mediator in the association between childhood adversity and anxious and depressive symptomatology (ADS) in adulthood. However, no previous study has assessed the independent mediating role of smoking in the association between childhood adversity and ADS in adulthood. Moreover, the importance of mediator-response confounding variables has rarely been demonstrated empirically in social and psychiatric epidemiology. The aim of this paper was to (i) assess the mediating role of smoking in adulthood in the association between childhood adversity and ADS in adulthood, and (ii) assess the change in estimates due to different mediator-response confounding factors (education, alcohol intake, and social support). The present analysis used data collected from 1994 to 2008 within the framework of the Tromsø Study (N = 4,530), a representative prospective cohort study of men and women. Seven childhood adversities (low mother's education, low father's education, low financial conditions, exposure to passive smoke, psychological abuse, physical abuse, and substance abuse distress) were used to create a childhood adversity score. Smoking status was measured at a mean age of 54.7 years (Tromsø IV), and ADS in adulthood was measured at a mean age of 61.7 years (Tromsø V). Mediation analysis was used to assess the indirect effect and the proportion of mediated effect (%) of childhood adversity on ADS in adulthood via smoking in adulthood. The test-retest reliability of smoking was good (Kappa: 0.67, 95% CI: 0.63; 0.71) in this sample. Childhood adversity was associated with a 10% increased risk of smoking in adulthood (Relative risk: 1.10, 95% CI: 1.03; 1.18), and both childhood adversity and smoking in adulthood were associated with greater levels of ADS in adulthood (p < 0.001). Smoking in adulthood did not significantly mediate the association between childhood adversity and ADS in adulthood. However, when education was excluded as a mediator-response confounding variable, the indirect effect of childhood adversity on ADS in adulthood was statistically significant (p < 0.05). This study shows that a careful inclusion of potential confounding variables is important when assessing mediation. PMID:28824498

Type and Timing of Menopause and Later Life Mortality Among Women in the Iowa Established Populations for the Epidemiological Study of the Elderly Cohort

PubMed Central

Cooper, Rachel; Wallace, Robert B.; Guralnik, Jack M.

2012-01-01

Abstract Background The relationship between menopausal characteristics and later life mortality is unclear. We tested the hypotheses that women with surgical menopause would have increased all-cause and cardiovascular mortality compared with women with natural menopause, and that women with earlier ages at natural or surgical menopause would have greater all-cause and cardiovascular mortality than women with later ages at menopause. Methods Women who participated in the Iowa cohort of the Established Populations for the Epidemiologic Study of the Elderly (n=1684) reported menopausal characteristics and potential confounding variables at baseline and were followed up for up to 24 years. Participants were aged 65 years or older at baseline and lived in rural areas. We used survival analysis to examine the relationships between menopausal characteristics and all-cause and cardiovascular mortality. Results A total of 1477 women (87.7% of respondents) died during the study interval. Women with an age at natural menopause ≥55 years had increased all-cause and cardiovascular disease mortality compared with women who had natural menopause at younger ages. Type of menopause and age at surgical menopause were not related to mortality. These patterns persisted after adjustment for potential confounding variables. Conclusions Among an older group of women from a rural area of the United States, later age at natural menopause was related to increased all-cause and cardiovascular mortality. Monitoring the cardiovascular health of this group of older women may contribute to improved survival times. PMID:21970557

Effects of categorization method, regression type, and variable distribution on the inflation of Type-I error rate when categorizing a confounding variable.

PubMed

Barnwell-Ménard, Jean-Louis; Li, Qing; Cohen, Alan A

2015-03-15

The loss of signal associated with categorizing a continuous variable is well known, and previous studies have demonstrated that this can lead to an inflation of Type-I error when the categorized variable is a confounder in a regression analysis estimating the effect of an exposure on an outcome. However, it is not known how the Type-I error may vary under different circumstances, including logistic versus linear regression, different distributions of the confounder, and different categorization methods. Here, we analytically quantified the effect of categorization and then performed a series of 9600 Monte Carlo simulations to estimate the Type-I error inflation associated with categorization of a confounder under different regression scenarios. We show that Type-I error is unacceptably high (>10% in most scenarios and often 100%). The only exception was when the variable categorized was a continuous mixture proxy for a genuinely dichotomous latent variable, where both the continuous proxy and the categorized variable are error-ridden proxies for the dichotomous latent variable. As expected, error inflation was also higher with larger sample size, fewer categories, and stronger associations between the confounder and the exposure or outcome. We provide online tools that can help researchers estimate the potential error inflation and understand how serious a problem this is. Copyright © 2014 John Wiley & Sons, Ltd.

Brief Communication: Latent toxoplasmosis and salivary testosterone concentration--important confounding factors in second to fourth digit ratio studies.

PubMed

Flegr, Jaroslav; Lindová, Jitka; Pivoñková, Vera; Havlícek, Jan

2008-12-01

A sexually dimorphic characteristic, the second to fourth digit ratio (2D:4D ratio), has been shown to reflect the prenatal concentration of sex steroid hormones and to correlate with many personality, physiological, and life history traits. The correlations are usually stronger for the right than the left hand. Most studies have shown that the 2D:4D ratio does not vary with age or postnatal concentration of sex steroid hormones. Recently, a strong association between left hand 2D:4D ratio and infection with a common human parasite Toxoplasma has been reported. We hypothesized that the confounding effect of Toxoplasma infection on left hand 2D:4D ratio could be responsible for the stronger association between different traits and right hand rather than left hand 2D:4D ratio. This confounding effect of toxoplasmosis could also be responsible for the difficulty in finding an association between 2D:4D ratio and age or postnatal steroid hormone concentration. To test this hypothesis, we analyzed the association between sex and age and 2D:4D ratio in a population of 194 female and 106 male students with and without controlling for the confounding variables of Toxoplasma infection and testosterone concentration. Our results showed that the relationship between age and sex and 2D:4D ratio increased sharply when Toxoplasma infection and testosterone concentration were controlled. These results suggest that left hand 2D:4D ratio is more susceptible to postnatal influences and that the confounding factors of Toxoplasma infection, testosterone concentration and possibly also age, should be controlled in future 2D:4D ratio studies. Because of a stronger 2D:4D dimorphism in Toxoplasma-infected than Toxoplasma-free subjects, we predict that 2D:4D ratio dimorphism as well as right hand/left hand 2D:4D ratio dimorphism will be higher in countries with a high prevalence of Toxoplasma infection than in those with a low prevalence. (c) 2008 Wiley-Liss, Inc.

Maternal Pre-Pregnancy Body Mass Index and Offspring Temperament and Behavior at 1 and 2 Years of Age

ERIC Educational Resources Information Center

Van Lieshout, Ryan J.; Schmidt, Louis A.; Robinson, Monique; Niccols, Alison; Boyle, Michael H.

2013-01-01

Recent research suggests that fetal exposure to increased maternal body mass index (BMI) during pregnancy may be associated with psychopathology later in life. When this link first emerges, and if it is due to intrauterine exposures or confounding variables is not known. We therefore assessed associations between maternal pre-pregnancy BMI and:…

Combining fixed effects and instrumental variable approaches for estimating the effect of psychosocial job quality on mental health: evidence from 13 waves of a nationally representative cohort study.

PubMed

Milner, Allison; Aitken, Zoe; Kavanagh, Anne; LaMontagne, Anthony D; Pega, Frank; Petrie, Dennis

2017-06-23

Previous studies suggest that poor psychosocial job quality is a risk factor for mental health problems, but they use conventional regression analytic methods that cannot rule out reverse causation, unmeasured time-invariant confounding and reporting bias. This study combines two quasi-experimental approaches to improve causal inference by better accounting for these biases: (i) linear fixed effects regression analysis and (ii) linear instrumental variable analysis. We extract 13 annual waves of national cohort data including 13 260 working-age (18-64 years) employees. The exposure variable is self-reported level of psychosocial job quality. The instruments used are two common workplace entitlements. The outcome variable is the Mental Health Inventory (MHI-5). We adjust for measured time-varying confounders. In the fixed effects regression analysis adjusted for time-varying confounders, a 1-point increase in psychosocial job quality is associated with a 1.28-point improvement in mental health on the MHI-5 scale (95% CI: 1.17, 1.40; P < 0.001). When the fixed effects was combined with the instrumental variable analysis, a 1-point increase psychosocial job quality is related to 1.62-point improvement on the MHI-5 scale (95% CI: -0.24, 3.48; P = 0.088). Our quasi-experimental results provide evidence to confirm job stressors as risk factors for mental ill health using methods that improve causal inference. © The Author 2017. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Social class, income, education, area of residence and psychological distress: does social class have an independent effect on psychological distress in Antalya, Turkey?

PubMed

Belek, I

2000-02-01

The aim of this study is to determine the separate effects of social class, income, education and area of residence on psychological distress. The study also assesses whether the association between prevalence of high score on the 12-item General Health Questionnaire (GHQ 12) and social class is independent of other variables. Psychological distress was assessed by means of the GHQ 12. The study covered 1,092 adults aged 15 years or more living in two different quarters of Antalya. Social class status was defined by occupational position, with income, education and area of residence treated as confounders. Chi-square and logistic regression analyses were used to evaluate the data. Large inequalities in psychological distress by all variables were observed. Psychological distress was significantly associated with class status, after adjusting for income, education, area of residence and other potential confounders (age, sex and marital status). Class inequalities in psychological distress were observed between blue-collar workers/unqualified employees and bourgeoisie. These findings support the view that the recent widening of inequalities among social classes in Turkey pose a substantial threat to health.

Job Strain and the Cortisol Diurnal Cycle in MESA: Accounting for Between- and Within-Day Variability

PubMed Central

Rudolph, Kara E.; Sánchez, Brisa N.; Stuart, Elizabeth A.; Greenberg, Benjamin; Fujishiro, Kaori; Wand, Gary S.; Shrager, Sandi; Seeman, Teresa; Diez Roux, Ana V.; Golden, Sherita H.

2016-01-01

Evidence of the link between job strain and cortisol levels has been inconsistent. This could be due to failure to account for cortisol variability leading to underestimated standard errors. Our objective was to model the relationship between job strain and the whole cortisol curve, accounting for sources of cortisol variability. Our functional mixed-model approach incorporated all available data—18 samples over 3 days—and uncertainty in estimated relationships. We used employed participants from the Multi-Ethnic Study of Atherosclerosis Stress I Study and data collected between 2002 and 2006. We used propensity score matching on an extensive set of variables to control for sources of confounding. We found that job strain was associated with lower salivary cortisol levels and lower total area under the curve. We found no relationship between job strain and the cortisol awakening response. Our findings differed from those of several previous studies. It is plausible that our results were unique to middle- to older-aged racially, ethnically, and occupationally diverse adults and were therefore not inconsistent with previous research among younger, mostly white samples. However, it is also plausible that previous findings were influenced by residual confounding and failure to propagate uncertainty (i.e., account for the multiple sources of variability) in estimating cortisol features. PMID:26905339

Which Propensity Score Method Best Reduces Confounder Imbalance? An Example From a Retrospective Evaluation of a Childhood Obesity Intervention.

PubMed

Schroeder, Krista; Jia, Haomiao; Smaldone, Arlene

Propensity score (PS) methods are increasingly being employed by researchers to reduce bias arising from confounder imbalance when using observational data to examine intervention effects. The purpose of this study was to examine PS theory and methodology and compare application of three PS methods (matching, stratification, weighting) to determine which best improves confounder balance. Baseline characteristics of a sample of 20,518 school-aged children with severe obesity (of whom 1,054 received an obesity intervention) were assessed prior to PS application. Three PS methods were then applied to the data to determine which showed the greatest improvement in confounder balance between the intervention and control group. The effect of each PS method on the outcome variable-body mass index percentile change at one year-was also examined. SAS 9.4 and Comprehensive Meta-analysis statistical software were used for analyses. Prior to PS adjustment, the intervention and control groups differed significantly on seven of 11 potential confounders. PS matching removed all differences. PS stratification and weighting both removed one difference but created two new differences. Sensitivity analyses did not change these results. Body mass index percentile at 1 year decreased in both groups. The size of the decrease was smaller in the intervention group, and the estimate of the decrease varied by PS method. Selection of a PS method should be guided by insight from statistical theory and simulation experiments, in addition to observed improvement in confounder balance. For this data set, PS matching worked best to correct confounder imbalance. Because each method varied in correcting confounder imbalance, we recommend that multiple PS methods be compared for ability to improve confounder balance before implementation in evaluating treatment effects in observational data.

Appendicular and whole body lean mass outcomes are associated with finite element analysis-derived bone strength at the distal radius and tibia in adults aged 40years and older.

PubMed

Gibbs, Jenna C; Giangregorio, Lora M; Wong, Andy K O; Josse, Robert G; Cheung, Angela M

2017-10-01

The purpose of this cross-sectional study was to determine how appendicular lean mass index (ALMI), and whole body lean (LMI) and fat mass indices (FMI) associate with estimated bone strength outcomes at the distal radius and tibia in adults aged 40 years and older. Dual energy X-ray absorptiometry (DXA) scans were performed to determine body composition, including whole body lean and fat mass, and appendicular lean mass. ALMI (appendicular lean mass/height 2 ), LMI (lean tissue mass/height 2 ) and FMI (fat mass/height 2 ) were calculated. High-resolution peripheral quantitative computed tomography (HRpQCT) scans were performed to assess bone structural properties at the distal radius and tibia. Using finite element analysis, failure load (N), stiffness (N/mm), ultimate stress (MPa), and cortical-to-trabecular load ratio were estimated from HRpQCT scans. The associations between body composition (ALMI, LMI, FMI) and estimated bone strength were examined using bivariate and multivariable linear regression analyses adjusting for age, sex, and other confounding variables. In 197 participants (127 women; mean±SD, age: 69.5±10.3y, body mass index: 27.95±4.95kg/m 2 , ALMI: 7.31±1.31kg/m 2 ), ALMI and LMI were significantly associated with failure load at the distal radius and tibia (explained 39%-48% of the variance) and remained significant after adjusting for confounding variables and multiple testing (R 2 =0.586-0.645, p<0.001). ALMI, LMI, and FMI did not have significant associations with ultimate stress in our multivariable models. FMI was significantly associated with cortical-to-trabecular load ratio at the distal radius and tibia (explained 6%-12% of the variance) and remained significant after adjusting for confounders and multiple testing (R 2 =0.208-0.243, p<0.001). FMI was no longer significantly associated with failure load after adjusting for confounders. These findings suggest that ALMI and LMI are important determinants of estimated bone strength, particularly failure load, at the distal radius and tibia, and may contribute to preservation of bone strength in middle-to-late adulthood. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of bilingualism on vocabulary, executive functions, age of dementia onset, and regional brain structure.

PubMed

Gasquoine, Philip Gerard

2016-11-01

To review the current literature on the effects of bilingualism on vocabulary, executive functions, age of dementia onset, and regional brain structure. PubMed and PsycINFO databases were searched (from January 1999 to present) for relevant original research and review articles on bilingualism (but not multilingualism) paired with each target neuropsychological variable published in English. A qualitative review of these articles was conducted. It has long been known that mean scores of bilinguals fall below those of monolinguals on vocabulary and other language, but not visual-perceptual, format cognitive tests. Contemporary studies that have reported higher mean scores for bilinguals than monolinguals on executive function task-switching or inhibition tasks have not always been replicated, leading to concerns of publication bias, statistical flaws, and failures to match groups on potentially confounding variables. Studies suggesting the onset of Alzheimer's disease occurred about 4 years later for bilinguals versus monolinguals have not been confirmed in longitudinal, cohort, community-based, incidence studies that have used neuropsychological testing and diagnostic criteria to establish an age of dementia diagnosis. Neuroimaging studies of regional gray and white matter volume in bilinguals versus monolinguals show inconsistencies in terms of both the regions of difference and the nature of the difference. Resolving inconsistencies in the behavioral data is necessary before searching in the brain for neuroanatomical correlation. Comparisons of balanced versus language-dominant groups within the same ethnoculture combined with objective measurement of bilingualism could better match groups on potentially confounding variables. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Perceived neighborhood environment and physical activity among high school students from Curitiba, Brazil.

PubMed

Lopes, Adalberto Aparecido dos Santos; Lanzoni, Alessandra Nunes; Hino, Adriano Akira Ferreira; Rodriguez-Añez, Ciro Romélio; Reis, Rodrigo Siqueira

2014-12-01

To analyze the association between perceived neighborhood environment and physical activity (PA) in high school students from Curitiba (PR), Brazil. A sample of 1,611 high school students from public schools was surveyed. The PA was assessed through questions, engaged for at least 20 minutes or 60 minutes. Perceptions on neighborhood environment were assessed through ten questions about neighborhood characteristics. Gender, age and number of cars in the household were self-reported and used as confounding variables. Absolute and relative frequencies were used in the sample, and associations were tested through adjusted logistic regressions for the confounding variables and stratified by gender (p < 0.05). The adjusted analyses showed that the variables "interesting things" among girls (OR = 1.77; 95%CI 1.05 - 2.96) and "there are places I like" (OR = 2.18; 95%CI 1.33 - 3.58) and "I see people my age", among boys, were associated with PA of at least 20 minutes/day once a week. Additionally, among boys, "I see people my age" was associated with 60-minute (OR = 1.68; 95%CI 1.15 - 2.45). Perceiving the neighborhood environment as "very good" was associated with higher chances of taking up PA among girls (OR = 1.92; 95%CI 1.15 - 3.22) and boys (OR = 3.13; 95%CI 1.97 - 4.97). A positive perception of the environment was associated to PA practice among boys and girls in this sample. The results suggest that some environmental characteristics which make neighborhoods more attractive could be related to PA among adolescents.

Prenatal Maternal Stress Associated with ADHD and Autistic Traits in early Childhood

PubMed Central

Ronald, Angelica; Pennell, Craig E.; Whitehouse, Andrew J. O.

2010-01-01

Research suggests that offspring of mothers who experience high levels of stress during pregnancy are more likely to have problems in neurobehavioral development. There is preliminary evidence that prenatal maternal stress (PNMS) is a risk factor for both autism and attention deficit hyperactivity disorder (ADHD), however most studies do not control for confounding factors and no study has investigated PNMS as a risk factor for behaviors characteristic of these disorders in early childhood. A population cohort of 2900 pregnant women were recruited before their 18th week of pregnancy and investigated prospectively. Maternal experience of stressful life events was assessed during pregnancy. When offspring were age 2 years, mothers completed the child behavior checklist. Multiple regression showed that maternal stressful events during pregnancy significantly predicted ADHD behaviors in offspring, after controlling for autistic traits and other confounding variables, in both males (p = 0.03) and females (p = 0.01). Similarly, stressful events during pregnancy significantly predicted autistic traits in the offspring after controlling for ADHD behaviors and confounding variables, in males only (p = 0.04). In conclusion, this study suggests that PNMS, in the form of typical stressful life events such as divorce or a residential move, show a small but significant association with both autistic traits and ADHD behaviors independently, in offspring at age 2 years, after controlling for multiple antenatal, obstetric, postnatal, and sociodemographic covariates. This finding supports future research using epigenetic, cross-fostering, and gene–environment interaction designs to identify the causal processes underlying this association. PMID:21833278

Symptom Severity Predicts Prolonged Recovery after Sport-Related Concussion: Age and Amnesia Do Not

PubMed Central

Meehan, William P.; Mannix, Rebekah C.; Stracciolini, Andrea; Elbin, R.J.; Collins, Michael W.

2013-01-01

Objective To identify predictors of prolonged symptoms for athletes who sustain concussions. Study design We conducted a multi-center, prospective, cohort study of patients in 2 sport concussion clinics. Possible predictors of prolonged symptoms from concussion were compared between two groups: those whose symptoms resolved within 28 days and those whose symptoms persisted beyond 28 days. Candidate predictor variables were entered into a logistic regression model that was used to generate adjusted odds ratios. Results During the study period, 182 patients met inclusion criteria. The mean age was 15.2 years (SD 3.04 years). Over a third (N=65) of patients underwent computerized neurocognitive testing on their initial visit. In univariate analyses, Post Concussion Symptom Scale (PCSS) score and all composite scores on computerized neurocognitive testing appeared to be associated with prolonged symptom duration. Sex, age, loss of consciousness at time of injury and amnesia at time of injury were not associated with prolonged symptom duration. After adjusting for potential confounding, however, only total score on the PCSS score was associated with the odds of suffering prolonged symptoms. Conclusions After adjusting for other potential confounding variables, only total score on the PCSS was associated with the odds of suffering prolonged symptoms from sport-related concussions; age and amnesia were not. Further efforts to develop clinical tools for predicting which athletes will suffer prolonged recoveries after concussion should focus on initial symptom score. PMID:23628374

Assessing the Independent Contribution of Maternal Educational Expectations to Children’s Educational Attainment in Early Adulthood: A Propensity Score Matching Analysis

PubMed Central

Pingault, Jean Baptiste; Côté, Sylvana M.; Petitclerc, Amélie; Vitaro, Frank; Tremblay, Richard E.

2015-01-01

Background Parental educational expectations have been associated with children’s educational attainment in a number of long-term longitudinal studies, but whether this relationship is causal has long been debated. The aims of this prospective study were twofold: 1) test whether low maternal educational expectations contributed to failure to graduate from high school; and 2) compare the results obtained using different strategies for accounting for confounding variables (i.e. multivariate regression and propensity score matching). Methodology/Principal Findings The study sample included 1,279 participants from the Quebec Longitudinal Study of Kindergarten Children. Maternal educational expectations were assessed when the participants were aged 12 years. High school graduation – measuring educational attainment – was determined through the Quebec Ministry of Education when the participants were aged 22–23 years. Findings show that when using the most common statistical approach (i.e. multivariate regressions to adjust for a restricted set of potential confounders) the contribution of low maternal educational expectations to failure to graduate from high school was statistically significant. However, when using propensity score matching, the contribution of maternal expectations was reduced and remained statistically significant only for males. Conclusions/Significance The results of this study are consistent with the possibility that the contribution of parental expectations to educational attainment is overestimated in the available literature. This may be explained by the use of a restricted range of potential confounding variables as well as the dearth of studies using appropriate statistical techniques and study designs in order to minimize confounding. Each of these techniques and designs, including propensity score matching, has its strengths and limitations: A more comprehensive understanding of the causal role of parental expectations will stem from a convergence of findings from studies using different techniques and designs. PMID:25803867

Impact of singlehood during pregnancy on dietary intake and birth outcomes- a study in the Norwegian Mother and Child Cohort Study.

PubMed

Farbu, Jorunn; Haugen, Margaretha; Meltzer, Helle Margrete; Brantsæter, Anne Lise

2014-12-05

Little attention has been given to the impact of singlehood during pregnancy. The aim of this study was to examine the impact of marital status on diet during pregnancy and pregnancy outcome. The study population comprised 62,773 women participating in the Norwegian Mother and Child Cohort Study. Marital status was categorised into singles living alone, singles living with parents and married/cohabiting (reference group). Participants answered a general health questionnaire in gestational week 15-17 and a food frequency questionnaire in gestational week 22. We used nonparametric tests to compare dietary intakes by marital status, and multiple logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for infants being small for gestational age (SGA), large for gestational age (LGA), and preterm delivery (defined as delivery before gestational week 37). Single women living with parents had lower intakes of fruits and vegetables, higher intake of total energy, higher proportion of energy from added sugar, and lower intake of fibre than the reference group. Singles living alone also had a higher intake of added sugar. In both of the single groups, daily smoking was more prevalent than in women living with a partner. In analyses adjusted for maternal age, pre-pregnancy BMI, energy intake, energy contributed by protein, education, income, parity and nausea, single women living alone had increased risk of SGA with OR = 1.27 (95% CI: 1.05, 1.55). When smoking was included among the confounding variables, the association was no longer significant. Likewise, singles living alone had increased risk of preterm delivery, with OR = 1.32 (95% CI: 1.01, 1.72) in a partly adjusted model, but the association did not remain significant in a model fully adjusted for confounding variables. Single mothers had lower dietary quality and included more smokers than women who lived with a partner. Single mothers living alone had higher prevalence of SGA and preterm delivery, but the associations with adverse pregnancy outcomes were confounded by other variables. This study shows that single mothers should be given special attention during antenatal care and counselling.

African ancestry, lung function and the effect of genetics

PubMed Central

Wehrmeister, Fernando C.; Hartwig, Fernando P.; Perez-Padilla, Rogelio; Gigante, Denise P.; Barros, Fernando C.; Oliveira, Isabel O.; Ferreira, Gustavo D.; Horta, Bernardo L.

2015-01-01

African-Americans have smaller lung function compared with European-Americans. The aim of this study was to disentangle the contribution of genetics from other variables on lung function. A cohort was followed from birth to 30 years of age in Brazil. Several variables were collected: genomic analysis based on DNA; forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) obtained by spirometry; height measured by anthropometrists; and thorax circumference evaluated by photonic scanner. Crude and adjusted linear regression models were calculated according to African ancestry. The sample comprised 2869 participants out of 3701 members of the cohort. Males with higher African ancestry by DNA analysis had a smaller FEV1 (−0.13 L, 95% CI −0.23– −0.03 L) and FVC (−0.21 L, 95% CI −0.32– −0.09 L) compared with those with less African ancestry, having accounted for height, sitting to standing height ratio and other confounders. Similar effects were seen in females. After adjustment, ancestry remained significantly associated with lung function, but the large effect of adjustment for confounding among males (but not females) does not allow us to exclude the possibility that residual confounding may still account for these findings. PMID:25700383

Association between falls and depressive symptoms or visual impairment among Japanese young-old adults.

PubMed

Kojima, Reiji; Ukawa, Shigekazu; Ando, Masahiko; Kawamura, Takashi; Wakai, Kenji; Tsushita, Kazuyo; Tamakoshi, Akiko

2016-03-01

To investigate the association between falls and self-reported depressive symptoms or visual impairment among young-old adults. A total of 1904 participants (986 men and 918 women) aged 64 years from the New Integrated Suburban Seniority Investigation Project from 1996 to 2005, an age-specific cohort study in Nisshin, Japan, took part in the present study. Depressive symptoms were evaluated using the Geriatric Depression Scale. Visual impairment was assessed using a self-administered questionnaire. The outcome variable was self-reported injurious falls at the age of 70 years. Multivariate odds ratios (OR) and 95% confidence intervals (CI) of depressive symptoms and visual impairment for the incidence of falls were calculated using logistic regression models and adjusted for possible confounding factors. Overall, 77 (7.8%) men and 126 (13.7%) women reported falls within the past 1 year at age 70 years. Among women, depressive symptoms and visual impairment were significantly associated with falls after adjusting for potential confounders (OR 1.70, 95% CI 1.09-2.62; OR 2.34, 95% CI 1.45-3.71, respectively), but not among men. Women with both conditions had a significantly increased risk of falls after adjusting for potential confounders (OR 3.50, 95% CI 1.65-7.13) compared with those with neither condition; the association was not significant among men. Depressive symptoms and visual impairment at age 64 years were significantly associated with an increased risk of falls at age 70 years in Japanese women but not in men. The combination of the two symptoms had an even greater association with fall risk. © 2015 Japan Geriatrics Society.

Racial microstressors, racial self-concept, and depressive symptoms among male African Americans during the transition to adulthood.

PubMed

Kogan, Steven M; Yu, Tianyi; Allen, Kimberly A; Brody, Gene H

2015-04-01

Racial discrimination is a pervasive stressor that can undermine mental health among African American youth and young adults. Several studies identify links between racial discrimination and depressive symptoms; however, this research base does not focus on male African American youth who experience significant racism-related stress during the transition to young adulthood. Moreover, few prospective studies consider significant confounding variables that affect exposure to and perception of discriminatory treatment. In response to this need, we examined the effect of exposure to racial discrimination from ages 16 to 18 on depressive symptoms among male African Americans at age 20. Racial self-concept, one's sense of positivity about one's race, was examined as a mediator and self-control as a moderator. Hypotheses were tested with 222 participants, age 16 at baseline and age 20 at the endpoint. Participants provided self-report data at five time points. Exposure to racial discrimination from ages 16 to 18 predicted depressive symptoms at age 20, net of confounding influences. Racial self-concept mediated this effect. Self-control moderated the influence of discrimination on racial self-concept. This study underscores the salience of racial discrimination in the development of depressive symptoms among African American male youth and the clinical utility of interventions targeting racial pride and self-control.

An introduction to instrumental variables analysis: part 1.

PubMed

Bennett, Derrick A

2010-01-01

There are several examples in the medical literature where the associations of treatment effects predicted by observational studies have been refuted by evidence from subsequent large-scale randomised trials. This is because of the fact that non-experimental studies are subject to confounding - and confounding cannot be entirely eliminated even if all known confounders have been measured in the study as there may be unknown confounders. The aim of this 2-part methodological primer is to introduce an emerging methodology for estimating treatment effects using observational data in the absence of good randomised evidence known as the method of instrumental variables. Copyright © 2010 S. Karger AG, Basel.

Demographic factors influencing the GH system: Implications for the detection of GH doping in sport.

PubMed

Nelson, Anne E; Ho, Ken K Y

2009-08-01

Application of methods for detecting GH doping depend on being able to discriminate between abnormal levels due to doping and normal physiological levels of circulating proteins that change in response to exogenous administration. Constituents of the IGF and collagen systems have been shown to be promising markers of GH abuse. Their ultimate utility, however, depends on identification of the factors that regulate their concentrations in blood. Among these are demographic factors that are known to influence these markers in the general population. In a large cross-sectional study of the GH-responsive markers in over 1000 elite athletes from 12 countries representing 4 major ethnic groups and 10 sport types, we have shown that there is a significant negative correlation between age and all the IGF and collagen markers we studied, with a rapid decrease in early adolescence. Age was the major contribution to the variability, equivalent to >80% of the attributable variation in IGF-I and the collagen markers. The IGF axis markers were all significantly higher in women, and the collagen markers significantly higher in men, however, the contribution of gender was smaller than that of age, except for IGFBP-3 and ALS. BMI had a minor contribution to variability of the GH-responsive markers. After adjustment for the confounding influences of age, gender and BMI, the effect of ethnicity in elite athletes was trivial except for IGFBP-3 and ALS, which were both lower in Africans and higher in Caucasians. Compared to age and gender, the contribution of sport type was also modest. Our findings on the influence of age, gender, BMI and sport type have also been confirmed in a study of mostly Caucasian elite athletes in the post-competition setting. In conclusion, age and gender are the major determinants of variability for IGF-I and the collagen markers, whereas ethnicity and sport type have a minor influence. Therefore, a test based on IGF-I and the collagen markers must take age into account for men and women, and ethnicity and sport type are unlikely to be confounders for these markers.

Medication Use in Early-HD Participants in Track-HD: an Investigation of its Effects on Clinical Performance.

PubMed

Keogh, Ruth; Frost, Chris; Owen, Gail; Daniel, Rhian M; Langbehn, Doug R; Leavitt, Blair; Durr, Alexandra; Roos, Raymund A C; Landwehrmeyer, G Bernhard; Reilmann, Ralf; Borowsky, Beth; Stout, Julie; Craufurd, David; Tabrizi, Sarah J

2016-01-11

 Insufficient evidence exists to guide the long-term pharmacological management of Huntington's disease (HD) although most current interventions rely on symptomatic management. The effect of many frontline treatments on potential endpoints for HD clinical trials remains unknown. Our objective was to investigate how therapies widely used to manage HD affect the symptom for which they are prescribed and other endpoints using data from TRACK-HD. We used longitudinal models to estimate effects of medication use on performance on tests of motor, cognitive and neuropsychiatric function using data from 123 TRACK-HD stage 1/2 participants across four study visits. Adjustment for confounding by prior medication use, prior clinical performance, concomitant use of other medications, and baseline variables (sex, disease group, age, CAG, study site, education) enabled a closer-to-causal interpretation of the associations. Adjusting for baseline variables only, medication use was typically associated with worse clinical performance, reflecting greater medication use in more advanced patients. After additional adjustment for longitudinal confounders such "inverse" associations were generally eliminated and in the expected directions: participants taking neuroleptics tended to have better motor performance, improved affect and poorer cognitive performance, and those taking SSRI/SNRIs had less apathy, less affect and better total behaviour scores. However, we uncovered few statistically significant associations. Limitations include sample size and unmeasured confounding. In conclusion, adjustment for confounding by prior measurements largely eliminated associations between medication use and poorer clinical performance from simple analyses. However, there was little convincing evidence of causal effects of medication on clinical performance and larger cohorts or trials are needed.

Watching television for more than two hours increases the likelihood of reporting poor sleep quality among Brazilian schoolteachers.

PubMed

de Souza, Sara Carolina Scremin; Campanini, Marcela Zambrim; de Andrade, Selma Maffei; González, Alberto Durán; de Melo, Juliana Moura; Mesas, Arthur Eumann

2017-10-01

Although time spent watching television and sleep problems have increased in the last few decades, it is unclear whether these conditions are associated in working adults after controlling for lifestyle, job characteristics and other individual aspects. The present study analyzed the association between time spent watching television and sleep quality among teachers from public schools in Londrina, Brazil. In this cross-sectional study, information from the Pittsburgh Sleep Quality Index (PSQI) and about time spent watching television was obtained during personal interviews. Logistic regression models adjusted by the main confounders (sociodemographic, occupational and lifestyle variables) were used in the analyses. Among the 959 studied teachers (68.2% women, median age: 42years), teachers who watched >120min/day had a higher likelihood of reporting poor sleep quality (PSQI>5) (odds ratio=1.41; 95% confidence interval=1.01; 1.98) compared with those who watched television for up to 60min/day, regardless of gender, age, work hours, leisure time physical activity and other lifestyle variables. This association did not remain significant after the adjustment for health conditions, i.e., obesity, anxiety, depression and chronic pain, which may act as confounding variables in the relationship between watching television and poor sleep quality. Watching television for >120min/day was independently associated with poorer sleep quality, which should be considered in the prevention and treatment of sleep disturbances among working population. Copyright © 2017 Elsevier Inc. All rights reserved.

ERPs and Psychopathology. I. Behavioral process issues.

PubMed

Roth, W T; Tecce, J J; Pfefferbaum, A; Rosenbloom, M; Callaway, E

1984-01-01

The clinical study of ERPs has an inherent defect--a self-selection of clinical populations that hampers equating of clinically defined groups on factors extraneous to the independent variables. Such ex post facto studies increase the likelihood of confounding variables in the interpretation of findings. Hence, the development of lawful relationships between clinical variables and ERPs is impeded and the fulfillment of description, explanation, prediction, and control in brain science is thwarted. Proper methodologies and theory development can increase the likelihood of establishing these lawful relationships. One methodology of potential value in the clinical application of ERPs, particularly in studies of aging, is that of divided attention. Two promising theoretical developments in the understanding of brain functioning and aging are the distraction-arousal hypothesis and the controlled-automatic attention model. The evaluation of ERPs in the study of brain-behavior relations in clinical populations might be facilitated by the differentiation of concurrent, predictive, content, and construct validities.

Kangaroo-mother care method and neurobehavior of preterm infants.

PubMed

Silva, Margareth Gurgel de Castro; Barros, Marina Carvalho de Moraes; Pessoa, Úrsula Maria Lima; Guinsburg, Ruth

2016-04-01

To evaluate the effect of kangaroo-mother care (KMC) in preterm (PT) neurobehavior between 36 and 41 weeks post-conceptual age (PCA). A prospective cohort of 61 preterm infants with gestational age (GA) of 28-32 w evaluated by the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS), with 36-41 w PCA. Infants with clinical instability were excluded. They were analyzed in 2 groups: - Kangaroo (KAN): KMC for 7 or more days; Conventional (CON): did not receive KMC. Scores of the 13 NNNS variables were compared between groups and the effect of KMC in the scores of the variables of NNNS were evaluated by multiple linear regression, controlling for confounders. The KAN groups (n=24) and CON (n=37) were similar regarding main demographic and clinical maternal and neonatal characteristics. Mean GA was 30.3 w; and birth weight was 1170 g for both groups. PT of KAN group were admitted in KMC with PCA of 35.8 w (38.5 days of life) and remained with this care for 14.3 days. The NNNS was applied 13 days after the start of KMC. PT submitted to KMC showed higher quality of movements (KAN: 4.98 ± 0.53 vs CON: 4.53 ± 0.47; p=0.001) and lower scores on Signs of stress and abstinence (KAN: 0.03 ± 0.03 vs CON: 0.05 ± 0.03; p=0.001). Controlling for confounders, the KMC was associated with higher scores on the variables Attention, Quality of movements, and lower scores on Asymmetry and Signs of stress and abstinence. PT submitted to the KMC, compared to those non-submitted, have better neurobehavior performance between 36 and 41 weeks of post-conceptual age. Copyright © 2016. Published by Elsevier Ireland Ltd.

A community study on emotional distress among Arab and Jewish Israelis over the age of 60.

PubMed

Shemesh, Annarosa Anat; Kohn, Robert; Blumstein, Tzvia; Geraisy, Nabil; Novikov, Ilya; Levav, Itzhak

2006-01-01

The elderly constitute a vulnerable group for psychopathology, yet research on their mental health among both Arab and Jews in Israel remains limited. The same is the case in Arab countries. This paper reports on the contrasting distribution of the mean emotional distress (ED) scores and rates of suspected clinical cases, and their related risk factors, among community residents over the age of 60. Several national agencies conducted a survey on 5,055 elderly individuals to investigate their health status, including ED. The interview included socio-demographic and behavioral health items, as well as a modified 12 item-GHQ as a measure of ED. Total ED scores and prevalence rates for suspected psychopathology were calculated. Their respective risk factors were examined using univariate and multivariate methods. The ED scores were highest among Muslim Arabs (4.9), followed by Christian Arabs (4.2), Jews (3.1) and Druzes (2.8). Their estimated prevalence rates were 43.4%, 37.0%, 21.4%, and 17.0%, respectively. The gradient of these results remained unchanged in the multivariate analysis for ED scores adjusting for confounding variables. In contrast, logistic regression analysis controlling for confounding variables did not find a differential risk for suspected psychopathology between Arabs and Jews. Conceivably, the higher demoralization scores among elderly Arabs are associated with their minority status affiliation, as well as with the rapid social changes that have taken place in their midst. A cultural response style may be entertained as a possible explanation. However, these factors do not impact the risk for suspected psychopathology where no differential risk was noted after adjustments for confounders. Copyright 2005 John Wiley & Sons, Ltd.

The role of job strain in understanding midlife common mental disorder: a national birth cohort study.

PubMed

Harvey, Samuel B; Sellahewa, Dilan A; Wang, Min-Jung; Milligan-Saville, Josie; Bryan, Bridget T; Henderson, Max; Hatch, Stephani L; Mykletun, Arnstein

2018-06-01

Long-standing concerns exist about reverse causation and residual confounding in the prospective association between job strain and risk of future common mental disorders. We aimed to address these concerns through analysis of data collected in the UK National Child Development Study, a large British cohort study. Data from the National Child Development Study (n=6870) were analysed by use of multivariate logistic regression to investigate the prospective association between job strain variables at age 45 years and risk of future common mental disorders at age 50 years, controlling for lifetime psychiatric history and a range of other possible confounding variables across the lifecourse. Population attributable fractions were calculated to estimate the public health effect of job strain on midlife mental health. In the final model, adjusted for all measured confounders, high job demands (odds ratio 1·70, 95% CI 1·25-2·32; p=0·0008), low job control (1·89, 1·29-2·77; p=0·0010), and high job strain (2·22, 1·59-3·09; p<0·0001) remained significant independent predictors of future onset of common mental disorder. If causality is assumed, our findings suggest that 14% of new cases of common mental disorder could have been prevented through elimination of high job strain (population attributable fraction 0·14, 0·06-0·20). High job strain appears to independently affect the risk of future common mental disorders in midlife. These findings suggest that modifiable work-related risk factors might be an important target in efforts to reduce the prevalence of common mental disorders. iCare Foundation and Mental Health Branch, NSW Health. Copyright © 2018 Elsevier Ltd. All rights reserved.

An investigation into the relationship between age and physiological function in highly active older adults

PubMed Central

Pollock, Ross D; Carter, Scott; Velloso, Cristiana P; Duggal, Niharika A; Lord, Janet M; Lazarus, Norman R; Harridge, Stephen D R

2015-01-01

Despite extensive research, the relationship between age and physiological function remains poorly characterised and there are currently no reliable markers of human ageing. This is probably due to a number of confounding factors, particularly in studies of a cross-sectional nature. These include inter-subject genetic variation, as well as inter-generational differences in nutrition, healthcare and insufficient levels of physical activity as well as other environmental factors. We have studied a cohort of highly and homogeneously active older male (n = 84) and female (n = 41) cyclists aged 55–79 years who it is proposed represent a model for the study of human ageing free from the majority of confounding factors, especially inactivity. The aim of the study was to identify physiological markers of ageing by assessing the relationship between function and age across a wide range of indices. Each participant underwent a detailed physiological profiling which included measures of cardiovascular, respiratory, neuromuscular, metabolic, endocrine and cognitive functions, bone strength, and health and well-being. Significant associations between age and function were observed for many functions. The maximal rate of oxygen consumption ( showed the closest association with age (r = −0.443 to −0.664; P < 0.001), but even here the variance in age for any given level was high, precluding the clear identification of the age of any individual. The results of this cross-sectional study suggest that even when many confounding variables are removed the relationship between function and healthy ageing is complex and likely to be highly individualistic and that physical activity levels must be taken into account in ageing studies. Key Points The relationship between age and physiological function remains poorly defined and there are no physiological markers that can be used to reliably predict the age of an individual. This could be due to a variety of confounding genetic and lifestyle factors, and in particular to ill-defined and low levels of physical activity. This study assessed the relationship between age and a diverse range of physiological functions in a cohort of highly active older individuals (cyclists) aged 55–79 years in whom the effects of lifestyle factors would be ameliorated. Significant associations between age and function were observed for many functions. was most closely associated with age, but even here the variance in age for any given level was high, precluding the clear identification of the age of any individual. The data suggest that the relationship between human ageing and physiological function is highly individualistic and modified by inactivity. PMID:25565071

An investigation into the relationship between age and physiological function in highly active older adults.

PubMed

Pollock, Ross D; Carter, Scott; Velloso, Cristiana P; Duggal, Niharika A; Lord, Janet M; Lazarus, Norman R; Harridge, Stephen D R

2015-02-01

The relationship between age and physiological function remains poorly defined and there are no physiological markers that can be used to reliably predict the age of an individual. This could be due to a variety of confounding genetic and lifestyle factors, and in particular to ill-defined and low levels of physical activity. This study assessed the relationship between age and a diverse range of physiological functions in a cohort of highly active older individuals (cyclists) aged 55-79 years in whom the effects of lifestyle factors would be ameliorated. Significant associations between age and function were observed for many functions. V̇O2max was most closely associated with age, but even here the variance in age for any given level was high, precluding the clear identification of the age of any individual. The data suggest that the relationship between human ageing and physiological function is highly individualistic and modified by inactivity. Despite extensive research, the relationship between age and physiological function remains poorly characterised and there are currently no reliable markers of human ageing. This is probably due to a number of confounding factors, particularly in studies of a cross-sectional nature. These include inter-subject genetic variation, as well as inter-generational differences in nutrition, healthcare and insufficient levels of physical activity as well as other environmental factors. We have studied a cohort of highly and homogeneously active older male (n = 84) and female (n = 41) cyclists aged 55-79 years who it is proposed represent a model for the study of human ageing free from the majority of confounding factors, especially inactivity. The aim of the study was to identify physiological markers of ageing by assessing the relationship between function and age across a wide range of indices. Each participant underwent a detailed physiological profiling which included measures of cardiovascular, respiratory, neuromuscular, metabolic, endocrine and cognitive functions, bone strength, and health and well-being. Significant associations between age and function were observed for many functions. The maximal rate of oxygen consumption (V̇O2max) showed the closest association with age (r = -0.443 to -0.664; P < 0.001), but even here the variance in age for any given level was high, precluding the clear identification of the age of any individual. The results of this cross-sectional study suggest that even when many confounding variables are removed the relationship between function and healthy ageing is complex and likely to be highly individualistic and that physical activity levels must be taken into account in ageing studies. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Examining the Error of Mis-Specifying Nonlinear Confounding Effect with Application on Accelerometer-Measured Physical Activity

ERIC Educational Resources Information Center

Lee, Paul H.

2017-01-01

Purpose: Some confounders are nonlinearly associated with dependent variables, but they are often adjusted using a linear term. The purpose of this study was to examine the error of mis-specifying the nonlinear confounding effect. Methods: We carried out a simulation study to investigate the effect of adjusting for a nonlinear confounder in the…

Using propensity scores to estimate the effects of insecticides on stream invertebrates from observational data

USGS Publications Warehouse

Lester L. Yuan,; Amina I. Pollard,; Carlisle, Daren M.

2009-01-01

Analyses of observational data can provide insights into relationships between environmental conditions and biological responses across a broader range of natural conditions than experimental studies, potentially complementing insights gained from experiments. However, observational data must be analyzed carefully to minimize the likelihood that confounding variables bias observed relationships. Propensity scores provide a robust approach for controlling for the effects of measured confounding variables when analyzing observational data. Here, we use propensity scores to estimate changes in mean invertebrate taxon richness in streams that have experienced insecticide concentrations that exceed aquatic life use benchmark concentrations. A simple comparison of richness in sites exposed to elevated insecticides with those that were not exposed suggests that exposed sites had on average 6.8 fewer taxa compared to unexposed sites. The presence of potential confounding variables makes it difficult to assert a causal relationship from this simple comparison. After controlling for confounding factors using propensity scores, the difference in richness between exposed and unexposed sites was reduced to 4.1 taxa, a difference that was still statistically significant. Because the propensity score analysis controlled for the effects of a wide variety of possible confounding variables, we infer that the change in richness observed in the propensity score analysis was likely caused by insecticide exposure.

Using propensity scores to estimate the effects of insecticides on stream invertebrates from observational data

USGS Publications Warehouse

Yuan, L.L.; Pollard, A.I.; Carlisle, D.M.

2009-01-01

Analyses of observational data can provide insights into relationships between environmental conditions and biological responses across a broader range of natural conditions than experimental studies, potentially complementing insights gained from experiments. However, observational data must be analyzed carefully to minimize the likelihood that confounding variables bias observed relationships. Propensity scores provide a robust approach for controlling for the effects of measured confounding variables when analyzing observational data. Here, we use propensity scores to estimate changes in mean invertebrate taxon richness in streams that have experienced insecticide concentrations that exceed aquatic life use benchmark concentrations. A simple comparison of richness in sites exposed to elevated insecticides with those that were not exposed suggests that exposed sites had on average 6.8 fewer taxa compared to unexposed sites. The presence of potential confounding variables makes it difficult to assert a causal relationship from this simple comparison. After controlling for confounding factors using propensity scores, the difference in richness between exposed and unexposed sites was reduced to 4.1 taxa, a difference that was still statistically significant. Because the propensity score analysis controlled for the effects of a wide variety of possible confounding variables, we infer that the change in richness observed in the propensity score analysis was likely caused by insecticide exposure. ?? 2009 SETAC.

How well do parental and peer relationships in adolescence predict health in adulthood?

PubMed

Landstedt, Evelina; Hammarström, Anne; Winefield, Helen

2015-07-01

Although health effects of social relationships are well-researched, long-term health consequences of adolescent family as well as peer relationships are poorly understood. The aim of the study was to explore the prospective importance of parental and peer social relationships in adolescence on internalising and functional somatic symptoms in adulthood. Data were drawn from four waves of the Northern Swedish Cohort Study, response rate 94.3%, N=1001. Outcome variables were internalising and functional somatic symptoms at the ages of 21, 30 and 42. Relationship variables at age 16 were poor parental contact and three indicators of poor peer relationships. Associations were assessed in multivariate ordinal logistic regressions with adjustment for confounders and baseline health. Results show that the main relationships-related predictors of adult internalising symptoms were self-rated poor peer relationships in terms of spending time alone during after-school hours and poor parental relationship. Functional somatic symptoms on the other hand were most strongly associated with poor parental contact and not being happy with classmates at age 16. The quality of parental and peer relationships in adolescence predicts adult mental and functional somatic health as much as 26 years later, even when accounting for confounders and adolescent symptomatology. This study extends past research by exploring how both adolescent parental and peer relationships (self-reported as well as teacher reported) predict adult self-reported health. © 2015 the Nordic Societies of Public Health.

Tutorial in Biostatistics: Instrumental Variable Methods for Causal Inference*

PubMed Central

Baiocchi, Michael; Cheng, Jing; Small, Dylan S.

2014-01-01

A goal of many health studies is to determine the causal effect of a treatment or intervention on health outcomes. Often, it is not ethically or practically possible to conduct a perfectly randomized experiment and instead an observational study must be used. A major challenge to the validity of observational studies is the possibility of unmeasured confounding (i.e., unmeasured ways in which the treatment and control groups differ before treatment administration which also affect the outcome). Instrumental variables analysis is a method for controlling for unmeasured confounding. This type of analysis requires the measurement of a valid instrumental variable, which is a variable that (i) is independent of the unmeasured confounding; (ii) affects the treatment; and (iii) affects the outcome only indirectly through its effect on the treatment. This tutorial discusses the types of causal effects that can be estimated by instrumental variables analysis; the assumptions needed for instrumental variables analysis to provide valid estimates of causal effects and sensitivity analysis for those assumptions; methods of estimation of causal effects using instrumental variables; and sources of instrumental variables in health studies. PMID:24599889

Bilingualism delays age at onset of dementia, independent of education and immigration status.

PubMed

Mortimer, James A

2014-05-27

Editors' Note: Mortimer argues that important confounding variables may have biased the conclusion by Alladi et al. on the role of bilingualism in delaying the onset of dementia. Following Mortimer’s comments, Alladi et al. conducted additional analysis of their data to support their conclusion. The attitude of "close enough" is not appropriate when determining brain death. Stadlan comments and supports Frank’s call for action regarding this sensitive issue.

Relation between sick leave and selected exposure variables among women semiconductor workers in Malaysia

PubMed Central

Chee, H; Rampal, K

2003-01-01

Aims: To determine the relation between sick leave and selected exposure variables among women semiconductor workers. Methods: This was a cross sectional survey of production workers from 18 semiconductor factories. Those selected had to be women, direct production operators up to the level of line leader, and Malaysian citizens. Sick leave and exposure to physical and chemical hazards were determined by self reporting. Three sick leave variables were used; number of sick leave days taken in the past year was the variable of interest in logistic regression models where the effects of age, marital status, work task, work schedule, work section, and duration of work in factory and work section were also explored. Results: Marital status was strongly linked to the taking of sick leave. Age, work schedule, and duration of work in the factory were significant confounders only in certain cases. After adjusting for these confounders, chemical and physical exposures, with the exception of poor ventilation and smelling chemicals, showed no significant relation to the taking of sick leave within the past year. Work section was a good predictor for taking sick leave, as wafer polishing workers faced higher odds of taking sick leave for each of the three cut off points of seven days, three days, and not at all, while parts assembly workers also faced significantly higher odds of taking sick leave. Conclusion: In Malaysia, the wafer fabrication factories only carry out a limited portion of the work processes, in particular, wafer polishing and the processes immediately prior to and following it. This study, in showing higher illness rates for workers in wafer polishing compared to semiconductor assembly, has implications for the governmental policy of encouraging the setting up of wafer fabrication plants with the full range of work processes. PMID:12660374

Evaluation of uncontrolled confounding in studies of environmental exposures and neurobehavioral testing in children.

PubMed

Mink, Pamela J; Goodman, Michael; Barraj, Leila M; Imrey, Harriet; Kelsh, Michael A; Yager, Janice

2004-07-01

Neurobehavioral tests are commonly used in studies of children exposed to low-level environmental concentrations of compounds known to be neurotoxic at higher levels. However, uncontrolled or incomplete control for confounding makes interpretation of results problematic because effects of confounders are often stronger than the effects of primary interest. We examined a priori the potential impact of confounding in a hypothetical study evaluating the association of a potentially neurotoxic environmental exposure with neurobehavioral function in children. We used 2 outcome measures: the Bayley Scales of Infant Development Mental Development Index and the Stanford-Binet Intelligence Scale Composite Score. We selected 3 potential confounders: maternal intelligence, home environment, and socioeconomic status as measured by years of parental education. We conducted 3 sets of analyses measuring the effect of each of the 3 confounding factors alone, 2 confounders acting simultaneously, and all 3 confounders acting simultaneously. Relatively small differences (0.5 standard deviations) in confounding variables between "exposed" and "unexposed" groups, if unmeasured and unaccounted for in the analysis, could produce spurious differences in cognitive test scores. The magnitude of this difference (3-10 points) has been suggested to have a meaningful impact in populations. The method of measuring confounders (eg, maternal intelligence) could also substantially affect the results. It is important to carefully consider the impact of potential confounders during the planning stages of an observational study. Study-to-study differences in neurobehavioral outcomes with similar environmental exposures could be partially explained by differences in the adjustment for confounding variables. Copyright 2004 Lippincott Williams and Wilkins

The relationship between motor performance and parent-rated executive functioning in 3- to 5-year-old children: What is the role of confounding variables?

PubMed

Houwen, Suzanne; van der Veer, Gerda; Visser, Jan; Cantell, Marja

2017-06-01

It is generally agreed that motor performance and executive functioning (EF) are intertwined. As the literature on this issue concerning preschool children is scarce, we examined the relationship between motor performance and parent-rated EF in a sample of 3- to 5-year-old children with different levels of motor skill proficiency, while controlling for age, gender, socio-economic status (SES), and attention-deficit-hyperactivity disorder (ADHD) symptomatology. EF was reported by parents of 153 children (mean age 4years 1months, SD 8months; 75 male) by means of the Behaviour Rating Inventory of Executive Function-Preschool version (BRIEF-P). Parent-reported ADHD symptoms were assessed using the Hyperactivity-Inattention subscale of the Strengths and Difficulties Questionnaire3-4. In addition, the children performed the Movement Assessment Battery for Children-2 (MABC-2). Several weak to moderate relationships were found between the MABC-2 Total Score and the EF subscales. Once other variables such as age, gender, SES, and ADHD symptomatology were taken into account, the only BRIEF-P subscale that was associated with the MABC-2 Total Score was the Working Memory subscale. Compared to their typically developing peers, children who are at risk for motor coordination difficulties (⩽the 16th percentile on the MABC-2) performed poorly on the Working Memory subscale, which confirms the results of the regression analyses. The at risk group also performed significantly worse on the Planning/Organize subscale, however. This is one of the first studies investigating the relationship between motor performance and parent-rated EF in such a young age group. It shows that the relationship between motor performance and EF in young children is complex and may be influenced by the presence of confounding variables such as ADHD symptomatology. Copyright © 2017 Elsevier B.V. All rights reserved.

Racial Microstressors, Racial Self-Concept, and Depressive Symptoms Among Male African Americans During the Transition to Adulthood

PubMed Central

Kogan, Steven M.; Yu, Tianyi; Allen, Kimberly A.; Brody, Gene H.

2015-01-01

Racial discrimination is a pervasive stressor that can undermine mental health among African American youth and young adults. Several studies identify links between racial discrimination and depressive symptoms; however, this research base does not focus on male African American youth who experience significant racism-related stress during the transition to young adulthood. Moreover, few prospective studies consider significant confounding variables that affect exposure to and perception of discriminatory treatment. In response to this need, we examined the effect of exposure to racial discrimination from ages 16–18 on depressive symptoms among male African Americans at age 20. Racial self-concept, one’s sense of positivity about one’s race, was examined as a mediator and self-control as a moderator. Hypotheses were tested with 222 participants, age 16 at baseline and age 20 at the endpoint. Participants provided self-report data at 5 time points. Exposure to racial discrimination from ages 16–18 predicted depressive symptoms at age 20, net of confounding influences. Racial self-concept mediated this effect. Self-control moderated the influence of discrimination on racial self-concept. This study underscores the salience of racial discrimination in the development of depressive symptoms among African American male youth and the clinical utility of interventions targeting racial pride and self-control. PMID:25344920

Physical health-related quality of life in relation to metabolic health and obesity among men and women in Germany.

PubMed

Truthmann, Julia; Mensink, Gert B M; Bosy-Westphal, Anja; Hapke, Ulfert; Scheidt-Nave, Christa; Schienkiewitz, Anja

2017-06-10

This study examined sex-specific differences in physical health-related quality of life (HRQoL) across subgroups of metabolic health and obesity. We specifically asked whether (1) obesity is related to lower HRQoL independent of metabolic health status and potential confounders, and (2) whether associations are similar in men and women. We used cross-sectional data from the German Health Interview and Examination Survey 2008-11. Physical HRQoL was measured using the Short Form-36 version 2 physical component summary (PCS) score. Based on harmonized ATPIII criteria for the definition of the metabolic health and a body mass index ≥ 30 kg/m 2 to define obesity, individuals were classified as metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Sex-specific analyses including multivariable linear regression analyses were based on PCS as the dependent variable, metabolic health and obesity category as the independent variable with three categories and MHNO as the reference, and age, education, lifestyle and comorbidities as confounders. This study included 6860 participants (3298 men, 3562 women). Compared to MHNO, all other metabolic health and obesity categories had significantly lower PCS in both sexes. As reflected by the beta coefficients [95% confidence interval] from bivariable linear regression models, a significant inverse association with PCS was strongest for MUO (men: -7.0 [-8.2; -5.8]; women: -9.0 [-10.2; -7.9]), intermediate for MUNO (men: -4.2 [-5.3; -3.1]; women: -5.6 [-6.8; -4.4]) and least pronounced for MHO (men: -2.2 [-3.6; -0.8]; women -3.9 [-5.4; -2.5]). Differences in relation to MHNO remained statistically significant for all groups after adjusting for confounders, but decreased in particular for MUNO (men:-1.3 [-2.3; -0.3]; women: -1.5 [-2.7; -0.3]. Obesity was significantly related to lower physical HRQoL, independent of metabolic health status. Potential confounders including age, educational status, health-related behaviors, and comorbidities explained parts of the inverse relationship. Associations were evident in both sexes and consistently more pronounced among women than men.

The Impact of Childhood Obesity on Health and Health Service Use.

PubMed

Kinge, Jonas Minet; Morris, Stephen

2018-06-01

To test the impact of obesity on health and health care use in children, by the use of various methods to account for reverse causality and omitted variables. Fifteen rounds of the Health Survey for England (1998-2013), which is representative of children and adolescents in England. We use three methods to account for reverse causality and omitted variables in the relationship between BMI and health/health service use: regression with individual, parent, and household control variables; sibling fixed effects; and instrumental variables based on genetic variation in weight. We include all children and adolescents aged 4-18 years old. We find that obesity has a statistically significant and negative impact on self-rated health and a positive impact on health service use in girls, boys, younger children (aged 4-12), and adolescents (aged 13-18). The findings are comparable in each model in both boys and girls. Using econometric methods, we have mitigated several confounding factors affecting the impact of obesity in childhood on health and health service use. Our findings suggest that obesity has severe consequences for health and health service use even among children. © Health Research and Educational Trust.

The relationship between type D personality and chronic heart failure is not confounded by disease severity as assessed by BNP.

PubMed

Pelle, Aline J; van den Broek, Krista C; Szabó, Balázs; Kupper, Nina

2010-11-05

Psychological factors, like Type D personality (i.e., the tendency to experience negative emotions and to inhibit emotional distress) have been linked to impaired health outcomes. Criticism on the role of psychological factors in cardiac disease has postulated that such constructs may be confounded by disease severity. Hence, we examined whether Type D personality is associated with brain natriuretic peptide (BNP), a sensitive marker of disease severity in chronic heart failure (CHF), in 202 consecutive CHF outpatients. No differences in logBNP levels were found between Type D and non-Type D patients (t(200) = -1.03, p = .30). After adjusting for demographic and clinical confounders, Type D personality remained unassociated with logBNP levels (β=.04, p = .55), whereas older age (β = .27, p<.001), being prescribed beta-blockers (β = .15, p = .02), lower left ventricular ejection fraction (β = -.38, p<.0001), and kidney dysfunction (β = .17, p = .01) were associated with higher logBNP. To conclude, Type D personality was not associated with BNP in CHF outpatients, whereas clinical variables were associated with BNP. These findings oppose the suggestion that Type D personality is confounded by indicators of disease severity. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

Accounting for context in studies of health inequalities: a review and comparison of analytic approaches.

PubMed

Schempf, Ashley H; Kaufman, Jay S

2012-10-01

A common epidemiologic objective is to evaluate the contribution of residential context to individual-level disparities by race or socioeconomic position. We reviewed analytic strategies to account for the total (observed and unobserved factors) contribution of environmental context to health inequalities, including conventional fixed effects (FE) and hybrid FE implemented within a random effects (RE) or a marginal model. To illustrate results and limitations of the various analytic approaches of accounting for the total contextual component of health disparities, we used data on births nested within neighborhoods as an applied example of evaluating neighborhood confounding of racial disparities in gestational age at birth, including both a continuous and a binary outcome. Ordinary and RE models provided disparity estimates that can be substantially biased in the presence of neighborhood confounding. Both FE and hybrid FE models can account for cluster level confounding and provide disparity estimates unconfounded by neighborhood, with the latter having greater flexibility in allowing estimation of neighborhood-level effects and intercept/slope variability when implemented in a RE specification. Given the range of models that can be implemented in a hybrid approach and the frequent goal of accounting for contextual confounding, this approach should be used more often. Published by Elsevier Inc.

Methods to control for unmeasured confounding in pharmacoepidemiology: an overview.

PubMed

Uddin, Md Jamal; Groenwold, Rolf H H; Ali, Mohammed Sanni; de Boer, Anthonius; Roes, Kit C B; Chowdhury, Muhammad A B; Klungel, Olaf H

2016-06-01

Background Unmeasured confounding is one of the principal problems in pharmacoepidemiologic studies. Several methods have been proposed to detect or control for unmeasured confounding either at the study design phase or the data analysis phase. Aim of the Review To provide an overview of commonly used methods to detect or control for unmeasured confounding and to provide recommendations for proper application in pharmacoepidemiology. Methods/Results Methods to control for unmeasured confounding in the design phase of a study are case only designs (e.g., case-crossover, case-time control, self-controlled case series) and the prior event rate ratio adjustment method. Methods that can be applied in the data analysis phase include, negative control method, perturbation variable method, instrumental variable methods, sensitivity analysis, and ecological analysis. A separate group of methods are those in which additional information on confounders is collected from a substudy. The latter group includes external adjustment, propensity score calibration, two-stage sampling, and multiple imputation. Conclusion As the performance and application of the methods to handle unmeasured confounding may differ across studies and across databases, we stress the importance of using both statistical evidence and substantial clinical knowledge for interpretation of the study results.

Interpretational confounding is due to misspecification, not to type of indicator: comment on Howell, Breivik, and Wilcox (2007).

PubMed

Bollen, Kenneth A

2007-06-01

R. D. Howell, E. Breivik, and J. B. Wilcox (2007) have argued that causal (formative) indicators are inherently subject to interpretational confounding. That is, they have argued that using causal (formative) indicators leads the empirical meaning of a latent variable to be other than that assigned to it by a researcher. Their critique of causal (formative) indicators rests on several claims: (a) A latent variable exists apart from the model when there are effect (reflective) indicators but not when there are causal (formative) indicators, (b) causal (formative) indicators need not have the same consequences, (c) causal (formative) indicators are inherently subject to interpretational confounding, and (d) a researcher cannot detect interpretational confounding when using causal (formative) indicators. This article shows that each claim is false. Rather, interpretational confounding is more a problem of structural misspecification of a model combined with an underidentified model that leaves these misspecifications undetected. Interpretational confounding does not occur if the model is correctly specified whether a researcher has causal (formative) or effect (reflective) indicators. It is the validity of a model not the type of indicator that determines the potential for interpretational confounding. Copyright 2007 APA, all rights reserved.

Job Strain and the Cortisol Diurnal Cycle in MESA: Accounting for Between- and Within-Day Variability.

PubMed

Rudolph, Kara E; Sánchez, Brisa N; Stuart, Elizabeth A; Greenberg, Benjamin; Fujishiro, Kaori; Wand, Gary S; Shrager, Sandi; Seeman, Teresa; Diez Roux, Ana V; Golden, Sherita H

2016-03-01

Evidence of the link between job strain and cortisol levels has been inconsistent. This could be due to failure to account for cortisol variability leading to underestimated standard errors. Our objective was to model the relationship between job strain and the whole cortisol curve, accounting for sources of cortisol variability. Our functional mixed-model approach incorporated all available data-18 samples over 3 days-and uncertainty in estimated relationships. We used employed participants from the Multi-Ethnic Study of Atherosclerosis Stress I Study and data collected between 2002 and 2006. We used propensity score matching on an extensive set of variables to control for sources of confounding. We found that job strain was associated with lower salivary cortisol levels and lower total area under the curve. We found no relationship between job strain and the cortisol awakening response. Our findings differed from those of several previous studies. It is plausible that our results were unique to middle- to older-aged racially, ethnically, and occupationally diverse adults and were therefore not inconsistent with previous research among younger, mostly white samples. However, it is also plausible that previous findings were influenced by residual confounding and failure to propagate uncertainty (i.e., account for the multiple sources of variability) in estimating cortisol features. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Does the frequency of anxiety and depressive disorders differ between diagnostic subtypes of anorexia nervosa and bulimia?

PubMed

Godart, Nathalie; Berthoz, Sylvie; Rein, Zoé; Perdereau, Fabienne; Lang, François; Venisse, Jean-Luc; Halfon, Olivier; Bizouard, Pierre; Loas, Gwénolé; Corcos, Maurice; Jeammet, Philippe; Flament, Martine; Curt, Florence

2006-12-01

The objective of the present work is to determine whether the prevalence of depressive and anxiety disorders varies in subgroups of eating disorders (ED) according to age, ED duration, mode of care provision, and body mass index (BMI). Using the Mini International Neuropsychiatric Interview (MINI), the frequency of anxiety and depressive disorders was evaluated in 271 ED participants. Their prevalence was compared in subgroups of anorexics (AN-R and AN-BN) and bulimics (BN), both before and after controlling for potential confounding variables. Current or lifetime comorbidity of anxiety and depressive disorders did not differ between AN-R and AN-BN groups. Social phobia, panic disorders, and obsessive-compulsive disorder (OCD) were significantly more frequent in AN-BN and AN-R groups. Panic disorder was more frequent in the BN group. Several confounding factors, in particular those identified in the present study, may explain previous conflicting results on the frequency of anxiety and depressive disorders in ED. Nevertheless, the study confirmed that OCD is more frequent in AN, even after controlling for confounding factors. Copyright 2006 by Wiley Periodicals, Inc.

Attendance at cultural events, reading books or periodicals, and making music or singing in a choir as determinants for survival: Swedish interview survey of living conditions.

PubMed

Bygren, L O; Konlaan, B B; Johansson, S E

To investigate the possible influence of attendance at cultural events, reading books or periodicals, making music or singing in a choir as determinants for survival. A simple random sample was drawn of 15,198 individuals aged 16-74 years. Of these, 85% (12,982) were interviewed by trained non-medical interviewers between 1982 and 1983 about cultural activities. They were followed up with respect to survival until 31 December 1991. Swedish interview survey of living conditions comprising a random sample of the adult Swedish population. 12,675 people interviewed between 1982 and 1983. Survival of subjects after controlling for eight confounding variables: age, sex, education level, income, long term disease, social network, smoking, and physical exercise. 6,301 men and 6,374 women were followed up; 533 men and 314 women died during this period. The control variables influenced survival in the expected directions except for social network for men; a significant negative effective was found when the analysis was made separately for men and women. We found an influence on mortality when the eight control variables were controlled for in people who rarely attended events compared with those attending most often, the relative risk being 1.57 (95% confidence interval 1.18 to 2.09). Attendance at cultural events may have a positive influence on survival. Long term follow up of large samples with confounders that are well controlled for and with the cultural stimulation more highly specified should be used to try to falsify the hypothesis before experiments start.

Family characteristics and the use of maternal health services: a population-based survey in Eastern China.

PubMed

Zhang, Ling; Xue, Chengbing; Wang, Youjie; Zhang, Liuyi; Liang, Yuan

2016-01-01

Despite the benefits of maternal health services, these services are often underutilized, especially in the developing countries. The aim of the present study is to provide insight regarding factors affecting maternal health services use from the family perspective. We use data from the fourth National Health Services Survey in Jiangsu province of Eastern China to investigate the effect of family characteristics on the use of maternal health services. Family characteristics included whether or not living with parents, age of husband, husband's education, and husband's work status as well as family economic status. Demographic variables, social and environmental factors, and previous reproductive history were taken as potential confounders. Multiple logistic regression models were used to examine the independent effects of the family characteristic variables on maternal health service utilization. The data indicate that the percentages of prenatal care, postnatal visits and hospital delivery were 85.44, 65.12 and 99.59 % respectively. Living with parents was associated with less use of prenatal care and husband's age, education and employment status had no effect on the use of prenatal care after adjusting for potential confounding variables. Our findings suggest that maternal health education (especially the role of prenatal care) needs to be extended beyond the expectant mothers themselves to their parents and husbands. The difference of health care delivery as a result of traditional family culture may highlight the differences in factors influencing the use of postnatal visits and those influencing the use of prenatal care; which may be worthy of further study.

Understanding Cataract Risk in Aerospace Flight Crew And Review of Mechanisms of Cataract Formation

NASA Technical Reports Server (NTRS)

Jones, Jeffrey A.; McCarten, M.; Manuel, K.; Djojonegoro, B.; Murray, J.; Cucinotta, F.; Feiversen, A.; Wear, M.

2006-01-01

Induction of cataracts by occupational exposure in flight crew has been an important topic of interest in aerospace medicine in the past five years, in association with numerous reports of flight-associated disease incidences. Due to numerous confounding variables, it has been difficult to determine if there is increased cataract risk directly caused by interaction with the flight environment, specifically associated with added radiation exposure during flight. Military aviator records from the United States Air Force (USAF) and Navy (USN) and US astronauts at the National Aeronautics and Space Administration (NASA)/Lyndon B. Johnson Space Center (JSC) were evaluated for the presence, location and age of diagnosis of cataracts. Military aviators were found to have a statistically significant younger average age of onset of their cataracts compared with astronauts, however the incidence density of cataracts was found to be statistically higher in astronauts than in military aviators. USAF and USN aviator s cataracts were most commonly located in the posterior subcapsular region of the lens while astronauts cataracts were most likely to originate generally in the cortical zone. A prospective clinical trial which controls for confounding variables in examination technique, cataract classification, diet, exposure, and pharmacological intervention is needed to determine what percentage of the risk for cataracts are due to radiation, and how to best develop countermeasures to protect flight crews from radiation bioeffects in the future.

Plasma 17-alpha-OH-progesterone in female workers exposed to urban pollutants.

PubMed

Ciarrocca, M; Cerratti, D; Capozzella, A; Rosati, M V; Anzani, M F; Bernardini, A; Casale, T; Pimpinella, B; Tomei, G; Monti, C; Tomao, E; Tomei, F

2006-01-01

The aim of this study is to evaluate whether occupational exposure to urban pollutants could cause alteration in plasma 17-alpha-OH-P levels in female workers. After excluding the subjects with the principal confounding factors, traffic police and controls were matched by age, working life, age of menarche, menstrual cycle day, BMI, drinking habits, habitual consumption of soy and Italian coffee. 68 traffic police and 82 controls (7th day; follicular phase of the ovarian cycle), 37 traffic police and 20 controls (21st day; lutheal phase of the ovarian cycle) were included in the study and matched for the above mentioned variables. In follicular and lutheal phase of ovarian cycle, 17-alpha-OH-P mean levels and the distribution of 17-alpha-OH-P values were significantly higher in traffic police vs. controls. A higher instance of mental health disorders in traffic police vs. controls was found, although the difference was not significant. Considering that the potential confounding effect of extraneous factors was controlled by restricting the study population and by matching traffic police vs. controls on the above mentioned variables, our results suggest that occupational exposure to urban pollutants may alter plasma 17-alpha-OH-P concentrations. 17-alpha-OH-P could be used in an occupational setting as an early biomarker of exposure to urban pollutants, valuable for a group, even before the onset of related pathologies.

Drosophila melanogaster as a model system for the evaluation of anti-aging compounds.

PubMed

Jafari, Mahtab

2010-01-01

Understanding the causes of aging is a complex problem due to the multiple factors that influence aging, which include genetics, environment, metabolism and reproduction, among others. These multiple factors create logistical difficulties in the evaluation of anti-aging agents. There is a need for good model systems to evaluate potential anti-aging compounds. The model systems used should represent the complexities of aging in humans, so that the findings may be extrapolated to human studies, but they should also present an opportunity to minimize the variables so that the experimental results can be accurately interpreted. In addition to positively affecting lifespan, the impact of the compound on the physiologic confounders of aging, including fecundity and the health span--the period of life where an organism is generally healthy and free from serious or chronic illness--of the model organism needs to be evaluated. Fecundity is considered a major confounder of aging in fruit flies. It is well established that female flies that are exposed to toxic substances typically reduce their dietary intake and their reproductive output and display an artifactual lifespan extension. As a result, drugs that achieve longevity benefits by reducing fecundity as a result of diminished food intake are probably not useful candidates for eventual treatment of aging in humans and should be eliminated during the screening process. Drosophila melanogaster provides a suitable model system for the screening of anti-aging compounds as D. melanogaster and humans have many conserved physiological and biological pathways. In this paper, I propose an algorithm to screen anti-aging compounds using Drosophila melanogaster as a model system.

Familial trends in a population with macular holes.

PubMed

Kay, Christine Nichols; Pavan, Peter Reed; Small, Laurie Buccina; Zhang, Tao; Zamba, Gideon K D; Cohen, Steven Myles

2012-04-01

To determine if patients with macular hole report an increased family history of macular hole compared with control patients and compare the report of family history between patients with unilateral and bilateral macular holes. This was a multicenter case-control study. Charts of patients coded with diagnosis of macular hole were reviewed, and the diagnosis of idiopathic full-thickness macular hole was ascertained in 166 patients. The control group comprised 136 patients without macular hole or trauma who presented with senile cataract. Family history was obtained from all patients through a telephone interview. Six of 166 (3.6%) macular hole patients surveyed reported a history of macular hole in a primary relative compared with none of 136 (0.0%) control patients (odds ratio is infinity, with 95% confidence interval 1.295 to infinity); however, this finding may be explained by confounders such as age and number of family members. Two of the 142 (1.4%) patients with unilateral holes versus 4 of the 24 (16.7%) patients with bilateral holes reported a family history (odds ratio is 0.0714, with 95% confidence interval 0.0063 to 0.5537), and this finding remains significant when logistic regression is performed to evaluate variables of age and number of family members as potential confounders. There is an increased report of familial occurrence of macular hole in patients with macular holes compared with control patients; however, logistic regression relates this finding to variables of age and number of family members. Patients with bilateral macular holes are more likely to report a family history of macular hole than patients with unilateral macular holes, and this finding remains significant in the presence of age and number of family members. These findings may suggest a familial component to macular hole.

Keeping children safe at home: protocol for three matched case–control studies of modifiable risk factors for falls

PubMed Central

Kendrick, Denise; Stewart, Jane; Clacy, Rose; Coffey, Frank; Cooper, Nicola; Coupland, Carol; Hayes, Mike; McColl, Elaine; Reading, Richard; Sutton, Alex; M L Towner, Elizabeth; Craig Watson, Michael

2012-01-01

Background Childhood falls result in considerable morbidity, mortality and health service use. Despite this, little evidence exists on protective factors or effective falls prevention interventions in young children. Objectives To estimate ORs for three types of medically attended fall injuries in young children in relation to safety equipment, safety behaviours and hazard reduction and explore differential effects by child and family factors and injury severity. Design Three multicentre case–control studies in UK hospitals with validation of parental reported exposures using home observations. Cases are aged 0–4 years with a medically attended fall injury occurring at home, matched on age and sex with community controls. Children attending hospital for other types of injury will serve as unmatched hospital controls. Matched analyses will use conditional logistic regression to adjust for potential confounding variables. Unmatched analyses will use unconditional logistic regression, adjusted for age, sex, deprivation and distance from hospital in addition to other confounders. Each study requires 496 cases and 1984 controls to detect an OR of 0.7, with 80% power, 5% significance level, a correlation between cases and controls of 0.1 and a range of exposure prevalences. Main outcome measures Falls on stairs, on one level and from furniture. Discussion As the largest in the field to date, these case control studies will adjust for potential confounders, validate measures of exposure and investigate modifiable risk factors for specific falls injury mechanisms. Findings should enhance the evidence base for falls prevention for young children. PMID:22628151

Bilingualism delays age at onset of dementia, independent of education and immigration status.

PubMed

Alladi, Suvarna; Bak, Thomas H; Duggirala, Vasanta; Surampudi, Bapiraju; Shailaja, Mekala; Shukla, Anuj Kumar; Chaudhuri, Jaydip Ray; Kaul, Subhash

2013-11-26

The purpose of the study was to determine the association between bilingualism and age at onset of dementia and its subtypes, taking into account potential confounding factors. Case records of 648 patients with dementia (391 of them bilingual) diagnosed in a specialist clinic were reviewed. The age at onset of first symptoms was compared between monolingual and bilingual groups. The influence of number of languages spoken, education, occupation, and other potentially interacting variables was examined. Overall, bilingual patients developed dementia 4.5 years later than the monolingual ones. A significant difference in age at onset was found across Alzheimer disease dementia as well as frontotemporal dementia and vascular dementia, and was also observed in illiterate patients. There was no additional benefit to speaking more than 2 languages. The bilingual effect on age at dementia onset was shown independently of other potential confounding factors such as education, sex, occupation, and urban vs rural dwelling of subjects. This is the largest study so far documenting a delayed onset of dementia in bilingual patients and the first one to show it separately in different dementia subtypes. It is the first study reporting a bilingual advantage in those who are illiterate, suggesting that education is not a sufficient explanation for the observed difference. The findings are interpreted in the context of the bilingual advantages in attention and executive functions.

Spread of activation and deactivation in the brain: does age matter?

PubMed Central

Gordon, Brian A.; Tse, Chun-Yu; Gratton, Gabriele; Fabiani, Monica

2014-01-01

Cross-sectional aging functional MRI results are sometimes difficult to interpret, as standard measures of activation and deactivation may confound variations in signal amplitude and spread, which however, may be differentially affected by age-related changes in various anatomical and physiological factors. To disentangle these two types of measures, here we propose a novel method to obtain independent estimates of the peak amplitude and spread of the BOLD signal in areas activated (task-positive) and deactivated (task-negative) by a Sternberg task, in 14 younger and 28 older adults. The peak measures indicated that, compared to younger adults, older adults had increased activation of the task-positive network, but similar levels of deactivation in the task-negative network. Measures of signal spread revealed that older adults had an increased spread of activation in task-positive areas, but a starkly reduced spread of deactivation in task-negative areas. These effects were consistent across regions within each network. Further, there was greater variability in the anatomical localization of peak points in older adults, leading to reduced cross-subject overlap. These results reveal factors that may confound the interpretation of studies of aging. Additionally, spread measures may be linked to local connectivity phenomena and could be particularly useful to analyze age-related deactivation patterns, complementing the results obtained with standard peak and region of interest analyses. PMID:25360115

Heart period variability and psychopathology in urban boys at risk for delinquency.

PubMed

Pine, D S; Wasserman, G A; Miller, L; Coplan, J D; Bagiella, E; Kovelenku, P; Myers, M M; Sloan, R P

1998-09-01

To examine associations between heart period variability (HPV) and psychopathology in young urban boys at risk for delinquency, a series of 697-11-year-old younger brothers of adjudicated delinquents received a standardized psychiatric evaluation and an assessment of heart period variability (HPV). Psychiatric symptoms were rated in two domains: externalizing and internalizing psychopathology. Continuous measures of both externalizing and internalizing psychopathology were associated with reductions in HPV components related to parasympathetic activity. These associations could not be explained by a number of potentially confounding variables, such as age, ethnicity, social class, body size, or family history of hypertension. Although familial hypertension predicted reduced HPV and externalizing psychopathology, associations between externalizing psychopathology and HPV were independent of familial hypertension. Psychiatric symptoms are associated with reduced HPV in young urban boys at risk for delinquency.

Unilateral spatial neglect in the acute phase of ischemic stroke can predict long-term disability and functional capacity.

PubMed

Luvizutto, Gustavo José; Moliga, Augusta Fabiana; Rizzatti, Gabriela Rizzo Soares; Fogaroli, Marcelo Ortolani; Moura Neto, Eduardo de; Nunes, Hélio Rubens de Carvalho; Resende, Luiz Antônio de Lima; Bazan, Rodrigo

2018-05-21

The aim of this study was to assess the relationship between the degree of unilateral spatial neglect during the acute phase of stroke and long-term functional independence. This was a prospective study of right ischemic stroke patients in which the independent variable was the degree of spatial neglect and the outcome that was measured was functional independence. The potential confounding factors included sex, age, stroke severity, topography of the lesion, risk factors, glycemia and the treatment received. Unilateral spatial neglect was measured using the line cancellation test, the star cancellation test and the line bisection test within 48 hours of the onset of symptoms. Functional independence was measured using the modified Rankin and Barthel scales at 90 days after discharge. The relationship between unilateral spatial neglect and functional independence was analyzed using multiple logistic regression that was corrected for confounding factors. We studied 60 patients with a median age of 68 (34-89) years, 52% of whom were male and 74% of whom were Caucasian. The risk for moderate to severe disability increased with increasing star cancellation test scores (OR=1.14 [1.03-1.26], p=0.01) corrected for the stroke severity, which was a confounding factor that had a statistically positive association with disability (OR=1.63 [1.13-2.65], p=0.01). The best chance of functional independence decreased with increasing star cancellation test scores (OR=0.86 [0.78-0.96], p=0.006) corrected for the stroke severity, which was a confounding factor that had a statistically negative association with independence (OR=0.66 [0.48-0.92], p=0.017). The severity of unilateral spatial neglect in acute stroke worsens the degree of long-term disability and functional independence.

Association of Fatigue With Sarcopenia and its Elements: A Secondary Analysis of SABE-Bogotá

PubMed Central

Patino-Hernandez, Daniela; David-Pardo, David Gabriel; Borda, Miguel Germán; Pérez-Zepeda, Mario Ulises; Cano-Gutiérrez, Carlos

2017-01-01

Objective: Sarcopenia, fatigue, and depression are associated with higher mortality rates and adverse outcomes in the aging population. Understanding the association among clinical variables, mainly symptoms, is important for screening and appropriately managing these conditions. The aim of this article is to evaluate the association among sarcopenia and its elements with depression and fatigue. Method: We used cross-sectional data from 2012 SABE (Salud, Bienestar y Envejecimiento)-Bogotá study, which included 2,000 participants of ages ≥60 years. Sarcopenia and its elements were taken as the dependent variable, while fatigue and depression were the main independent variables. We tested the association among these through multiple logistic regression models, which were fitted for each dependent variable and adjusted for confounding variables. Results: Our findings showed that gait speed was associated with fatigue (adjusted odds ratio [OR] = 1.41, 95% confidence interval [CI] = [1.05, 1.90], p = .02) as well as abnormal handgrip strength (adjusted OR = 1.40, 95% CI = [1.02, 1.93], p = .04). No other associations were significant. Conclusion: While sarcopenia and fatigue are not associated, two of the sarcopenia-defining variables are associated with fatigue; this suggests that lack of sarcopenia does not exclude undesirable outcomes related to fatigue in aging adults. Also, the lack of association between sarcopenia-defining elements and depression demonstrates that depression and fatigue are different concepts. PMID:28474000

Histologic chorioamnionitis in preterm infants: correlation with brain magnetic resonance imaging at term equivalent age.

PubMed

Granger, Claire; Spittle, Alicia J; Walsh, Jennifer; Pyman, Jan; Anderson, Peter J; Thompson, Deanne K; Lee, Katherine J; Coleman, Lee; Dagia, Charuta; Doyle, Lex W; Cheong, Jeanie

2018-02-15

To explore the associations between histologic chorioamnionitis with brain injury, maturation and size on magnetic resonance imaging (MRI) of preterm infants at term equivalent age. Preterm infants (23-36 weeks' gestational age) were recruited into two longitudinal cohort studies. Presence or absence of chorioamnionitis was obtained from placental histology and clinical data were recorded. MRI at term-equivalent age was assessed for brain injury (intraventricular haemorrhage, cysts, signal abnormalities), maturation (degree of myelination, gyral maturation) and size of cerebral structures (metrics and brain segmentation). Histologic chorioamnionitis was assessed as a predictor of MRI variables using linear and logistic regression, with adjustment for confounding perinatal variables. Two hundred and twelve infants were included in this study, 47 (22%) of whom had histologic chorioamnionitis. Histologic chorioamnionitis was associated with higher odds of intraventricular haemorrhage (odds ratio [OR] (95% confidence interval [CI]) = 7.4 (2.4, 23.1)), less mature gyral maturation (OR (95% CI) = 2.0 (1.0, 3.8)) and larger brain volume (mean difference in cubic centimeter (95% CI) of 14.1 (1.9, 26.2)); but all relationships disappeared following adjustment for perinatal variables. Histologic chorioamnionitis was not independently associated with IVH, less mature gyral maturation or brain volume at term-equivalent age in preterm infants.

What is the association between wealth and mental health?

PubMed

Carter, K N; Blakely, T; Collings, S; Imlach Gunasekara, F; Richardson, K

2009-03-01

Socioeconomic inequalities in mental health have been shown in a number of populations. This study aims to investigate the association between asset wealth and psychological distress in New Zealand and whether it is independent of other socioeconomic measures and baseline health status. Data for this study were from the first three waves of the Survey of Families, Income and Employment (SoFIE) conducted in New Zealand (2002-2004/05) (n = 15 340). The Kessler-10 was used as a measure of psychological distress. The association of quintiles of wealth with psychological distress was investigated using logistic regression, controlling for confounders, socioeconomic variables and prior health status. The odds ratio (OR) of reporting high psychological distress were greater in the lowest wealth quintile compared with the highest (OR 3.06, 95% CI 2.68 to 3.50). Adjusting for age and sex did not alter the relationship; however, adjusting for income and area deprivation attenuated the OR to 1.73 (95% CI 1.48 to 2.04). Further controlling for baseline health status reduced the OR to 1.45 (95% CI 1.23 to 1.71), although the confidence interval still excluded the null. Inequalities in wealth are strongly associated with psychological distress, over and above other confounding demographic variables and baseline health status. Much, but not all, of that association is confounded by adult socioeconomic position. This suggests that policy measures to improve asset wealth, through savings and home ownership, may have positive health implications and help to reduce health inequalities.

Instrumental Variable Methods for Continuous Outcomes That Accommodate Nonignorable Missing Baseline Values.

PubMed

Ertefaie, Ashkan; Flory, James H; Hennessy, Sean; Small, Dylan S

2017-06-15

Instrumental variable (IV) methods provide unbiased treatment effect estimation in the presence of unmeasured confounders under certain assumptions. To provide valid estimates of treatment effect, treatment effect confounders that are associated with the IV (IV-confounders) must be included in the analysis, and not including observations with missing values may lead to bias. Missing covariate data are particularly problematic when the probability that a value is missing is related to the value itself, which is known as nonignorable missingness. In such cases, imputation-based methods are biased. Using health-care provider preference as an IV method, we propose a 2-step procedure with which to estimate a valid treatment effect in the presence of baseline variables with nonignorable missing values. First, the provider preference IV value is estimated by performing a complete-case analysis using a random-effects model that includes IV-confounders. Second, the treatment effect is estimated using a 2-stage least squares IV approach that excludes IV-confounders with missing values. Simulation results are presented, and the method is applied to an analysis comparing the effects of sulfonylureas versus metformin on body mass index, where the variables baseline body mass index and glycosylated hemoglobin have missing values. Our result supports the association of sulfonylureas with weight gain. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Does Anaemia Have Major Public Health Importance in Children Aged 6-59 Months in the Duggina Fanigo District of Wolaita Zone, Southern Ethiopia?

PubMed

Tiku, Yohannes Samuel; Mekonnen, Tefera Chane; Workie, Shimelash Bitew; Amare, Endale

2018-01-01

Globally, a large number of children aged 6-59 months are affected by anaemia. In Ethiopia, like other developing countries, more than 40% of children under 5 years are affected by anaemia. Anaemia during infancy and childhood period is associated with poor health and impaired cognitive development, leading to reduced academic achievement and earning potential in their adult life. The aim of this research was to assess whether anaemia remained a major public health problem among children aged 6-59 months or not in Duggina Fanigo District of Wolaita Zone, South Ethiopia in 2016. A community-based cross-sectional study was conducted from February to March 2016, on 404 mothers with children aged 6-59 months who were selected through the systematic sampling method. Socio-demographic and other data on associated factors was collected using a pre-tested questionnaire. Capillary blood was taken from the fingertip of each child and hemoglobin was measured using Haemo-Cue digital photometer. All the necessary safety measures were taken during blood collection. Data analysis was made using SPSS version 21. Multivariable logistic regression analysis was used to assess the association of independent variables with outcome variables and to control the possible confounding factors. The overall prevalence of anaemia was 51.4%. Anaemia was common among young children as compared to older children. After controlling the effect of confounding and adjusting for age, gender and altitude, explanatory variables like low dietary diversity (AOR = 3.24; 95% CI [1.68-6.23]), food insecurity (AOR = 3.63; 95% CI [2.18-6.04]), stunting (AOR = 2.60; 95% CI [1.56-4.35]), underweight (AOR = 2.46; 95% CI [1.29-4.67]) and fever within 2 weeks (AOR = 2.49; 95% CI [1.29-4.81]) prior to the survey were significantly associated with anaemia. In conclusion, the overall prevalence of anaemia among children aged 6-59 months has remained a major public health importance in the study area. Integrated efforts need to be prioritized to improve the health as well as the nutritional status of children aged 6-59 months through appropriate feeding practices in infants and children. © 2017 S. Karger AG, Basel.

Association between maternal age at childbirth and metabolic syndrome in postmenopausal women: Korea National Health and Nutrition Examination Survey 2010 to 2012.

PubMed

Shin, Jae Eun; Han, Kyung Do; Shin, Jong Chul; Lee, Young; Kim, Sa Jin

2017-02-01

The aim of this study was to evaluate the relationship between maternal age at childbirth and metabolic syndrome in postmenopausal women. We carried out a cross-sectional study on 3,956 Korean postmenopausal women who participated in the Korea National Health and Nutrition Examination Survey from 2010 to 2012. Multivariate logistic regression was used to evaluate the association between maternal age at first and last childbirth and metabolic syndrome, with adjustment for potential confounding variables. Women with metabolic syndrome had younger age at first delivery (23.3 ± 0.1 vs 24.4 ± 0.1 y, P < 0.001) and an older age at last delivery (30.8 ± 0.1 vs 30.3 ± 0.1 y, P = 0.011) than those without metabolic syndrome. After adjustments for confounding factors, earlier ages of first and last childbirth were positively associated with metabolic syndrome. The odds ratio (OR) was 2.157 (95% CI 1.256-3.705) for age at first childbirth, and 1.639 (95% CI 1.118-2.403) for age at last childbirth. Among the components of metabolic syndrome, only fasting glucose was positively associated with early age at first childbirth (OR 1.86; 95% CI 1.065-3.249) and early age at last childbirth (OR 1.71; 95% CI 1.197-2.444). A younger maternal age at first and last childbirth was independently associated with a higher risk of metabolic syndrome in postmenopausal women. Advanced maternal age at last childbirth was, however, not an independent risk factor for metabolic syndrome.

Using instrumental variables to estimate a Cox's proportional hazards regression subject to additive confounding

PubMed Central

Tosteson, Tor D.; Morden, Nancy E.; Stukel, Therese A.; O'Malley, A. James

2014-01-01

The estimation of treatment effects is one of the primary goals of statistics in medicine. Estimation based on observational studies is subject to confounding. Statistical methods for controlling bias due to confounding include regression adjustment, propensity scores and inverse probability weighted estimators. These methods require that all confounders are recorded in the data. The method of instrumental variables (IVs) can eliminate bias in observational studies even in the absence of information on confounders. We propose a method for integrating IVs within the framework of Cox's proportional hazards model and demonstrate the conditions under which it recovers the causal effect of treatment. The methodology is based on the approximate orthogonality of an instrument with unobserved confounders among those at risk. We derive an estimator as the solution to an estimating equation that resembles the score equation of the partial likelihood in much the same way as the traditional IV estimator resembles the normal equations. To justify this IV estimator for a Cox model we perform simulations to evaluate its operating characteristics. Finally, we apply the estimator to an observational study of the effect of coronary catheterization on survival. PMID:25506259

Using instrumental variables to estimate a Cox's proportional hazards regression subject to additive confounding.

PubMed

MacKenzie, Todd A; Tosteson, Tor D; Morden, Nancy E; Stukel, Therese A; O'Malley, A James

2014-06-01

The estimation of treatment effects is one of the primary goals of statistics in medicine. Estimation based on observational studies is subject to confounding. Statistical methods for controlling bias due to confounding include regression adjustment, propensity scores and inverse probability weighted estimators. These methods require that all confounders are recorded in the data. The method of instrumental variables (IVs) can eliminate bias in observational studies even in the absence of information on confounders. We propose a method for integrating IVs within the framework of Cox's proportional hazards model and demonstrate the conditions under which it recovers the causal effect of treatment. The methodology is based on the approximate orthogonality of an instrument with unobserved confounders among those at risk. We derive an estimator as the solution to an estimating equation that resembles the score equation of the partial likelihood in much the same way as the traditional IV estimator resembles the normal equations. To justify this IV estimator for a Cox model we perform simulations to evaluate its operating characteristics. Finally, we apply the estimator to an observational study of the effect of coronary catheterization on survival.

Size of age-0 crappies (Pomoxis spp.) relative to reservoir habitats and water levels

USGS Publications Warehouse

Kaczka, Levi J.; Miranda, Leandro E.

2014-01-01

Variable year-class strength is common in crappie Pomoxis spp. populations in many reservoirs, yet the mechanisms behind this variability are poorly understood. Size-dependent mortality of age-0 fishes has long been recognized in the population ecology literature; however, investigations about the effects of environmental factors on age-0 crappie size are lacking. The objective of this study was to determine if differences existed in total length of age-0 crappies between embayment and floodplain habitats in reservoirs, while accounting for potential confounding effects of water level and crappie species. To this end, we examined size of age-0 crappies in four flood-control reservoirs in northwest Mississippi over 4years. Age-0 crappies inhabiting uplake floodplain habitats grew to a larger size than fish in downlake embayments, but this trend depended on species, length of time a reservoir was dewatered in the months preceding spawning, and reservoir water level in the months following spawning. The results from our study indicate that water-level management may focus not only on allowing access to quality nursery habitat, but that alternating water levels on a multiyear schedule could increase the quality of degraded littoral habitats.

Color discrimination errors associate with axial motor impairments in Parkinson's disease.

PubMed

Bohnen, Nicolaas I; Haugen, Jacob; Ridder, Andrew; Kotagal, Vikas; Albin, Roger L; Frey, Kirk A; Müller, Martijn L T M

2017-01-01

Visual function deficits are more common in imbalance-predominant compared to tremor-predominant PD suggesting a pathophysiological role of impaired visual functions in axial motor impairments. To investigate the relationship between changes in color discrimination and motor impairments in PD while accounting for cognitive or other confounder factors. PD subjects (n=49, age 66.7±8.3 years; Hoehn & Yahr stage 2.6±0.6) completed color discrimination assessment using the Farnsworth-Munsell 100 Hue Color Vision Test, neuropsychological, motor assessments and [ 11 C]dihydrotetrabenazine vesicular monoamine transporter type 2 PET imaging. MDS-UPDRS sub-scores for cardinal motor features were computed. Timed up and go mobility and walking tests were assessed in 48 subjects. Bivariate correlation coefficients between color discrimination and motor variables were significant only for the Timed up and go (R S =0.44, P=0.0018) and the MDS-UPDRS axial motor scores (R S =0.38, P=0.0068). Multiple regression confounder analysis using the Timed up and go as outcome parameter showed a significant total model (F (5,43) = 7.3, P<0.0001) with significant regressor effects for color discrimination (standardized β=0.32, t=2.6, P=0.012), global cognitive Z-score (β=-0.33, t=-2.5, P=0.018), duration of disease (β=0.26, t=1.8, P=0.038), but not for age or striatal dopaminergic binding. The color discrimination test was also a significant independent regressor in the MDS-UPDRS axial motor model (standardized β=0.29, t=2.4, P=0.022; total model t (5,43) = 6.4, P=0.0002). Color discrimination errors associate with axial motor features in PD independent of cognitive deficits, nigrostriatal dopaminergic denervation, and other confounder variables. These findings may reflect shared pathophysiology between color discrimination visual impairments and axial motor burden in PD.

The effects of housework on the health of retired older adults: a preliminary investigation from the Tongji-Dongfeng cohort study, China.

PubMed

Wen, Xiaopiao; Liang, Yuan; Zhu, Jiang; Wu, Tangchun

2013-01-01

The aim of the current study was to explore the relationship between housework and health of retired older adults, and to provide new evidences and clues for the effects of housework on health. The data came from the baseline survey of the Tongji-Dongfeng Cohort Study with 25,501 participants. The independent variable was housework including child care, elder care, grocery shopping & cooking, and washing clothes & cleaning house. The dependent variable was self-reported two-week illness. Age, education, marital status, smoking and drinking were used as potential confounding variables. There are gender differences in the four types of housework, with higher prevalence among women than among men. The prevalence of two-week illness in women was higher than that in men. After adjusting for potential confounding variables, the four types of housework had almost no significant effects on two-week illness, except for washing clothes & cleaning house with a negative effect for women (OR = 1.17, 95% CI 1.06-1.29). The association of housework with health, especially of child care, elder care, and grocery shopping & cooking without significance and of washing clothes & cleaning house with significance for women, would provide a valuable clue for in-depth study of housework, namely the effects of housework on health would be subdivided into the dimensions of psychological and social activity besides physical activity, and it may not be suitable to simply classify housework as a kind of exercise.

Residential proximity to industrial sites in the area of Taranto (Southern Italy). A case-control cancer incidence study.

PubMed

Marinaccio, Alessandro; Belli, Stefano; Binazzi, Alessandra; Scarselli, Alberto; Massari, Stefania; Bruni, Antonella; Conversano, Michele; Crosignani, Paolo; Minerba, Aldo; Zona, Amerigo; Comba, Pietro

2011-01-01

The association between cancer incidence and the residence near polluting facilities in an industrial area nearby Taranto has been investigated. Age, sex and occupational exposure were controlled as confounding variables in a case-control study (658 cases, 2092 controls). High risks were evidenced close to the steel mill (OR: 3.54), coke plant (OR: 4.80), mineral deposit (OR: 3.33) and shipbuilding (OR: 4.29) for pleural neoplasm, and to the steel mill (OR: 1.65) and shipbuilding (OR: 1.79) for lung cancer. After adjustment for occupational exposure, increasing trends of risk were observed both for lung and bladder cancers. Cancer risks were evidenced near industrial sites and the introduction of "occupational exposure" as a confounder modified significantly the risks with respect to distance from the source of pollution, particularly for pleural, lung and bladder cancers.

Does long-term care use within primary health care reduce hospital use among older people in Norway? A national five-year population-based observational study

PubMed Central

2011-01-01

Background Population ageing may threaten the sustainability of future health care systems. Strengthening primary health care, including long-term care, is one of several measures being taken to handle future health care needs and budgets. There is limited and inconsistent evidence on the effect of long-term care on hospital use. We explored the relationship between the total use of long-term care within public primary health care in Norway and the use of hospital beds when adjusting for various effect modifiers and confounders. Methods This national population-based observational study consists of all Norwegians (59% women) older than 66 years (N = 605676) (13.2% of total population) in 2002-2006. The unit of analysis was defined by municipality, age and sex. The association between total number of recipients of long-term care per 1000 inhabitants (LTC-rate) and hospital days per 1000 inhabitants (HD-rate) was analysed in a linear regression model. Modifying and confounding effects of socioeconomic, demographic and geographic variables were included in the final model. We defined a difference in hospitalization rates of more than 1000 days per 1000 inhabitants as clinically important. Results Thirty-one percent of women and eighteen percent of men were long-term care users. Men had higher HD-rates than women. The crude association between LTC-rate and HD-rate was weakly negative. We identified two effect modifiers (age and sex) and two strong confounders (travel time to hospital and mortality). Age and sex stratification and adjustments for confounders revealed a positive statistically significant but not clinically important relationship between LTC-rates and hospitalization for women aged 67-79 years and all men. For women 80 years and over there was a weak but negative relationship which was neither statistically significant nor clinically important. Conclusions We found a weak positive adjusted association between LTC-rates and HD-rates. Opposite to common belief, we found that increased volume of LTC by itself did not reduce pressure on hospitals. There still is a need to study integrated care models for the elderly in the Norwegian setting and to explore further why municipalities far away from hospital achieve lower use of hospital beds. PMID:22029775

Attendance at cultural events, reading books or periodicals, and making music or singing in a choir as determinants for survival: Swedish interview survey of living conditions.

PubMed Central

Bygren, L. O.; Konlaan, B. B.; Johansson, S. E.

1996-01-01

OBJECTIVES: To investigate the possible influence of attendance at cultural events, reading books or periodicals, making music or singing in a choir as determinants for survival. DESIGN: A simple random sample was drawn of 15,198 individuals aged 16-74 years. Of these, 85% (12,982) were interviewed by trained non-medical interviewers between 1982 and 1983 about cultural activities. They were followed up with respect to survival until 31 December 1991. SETTING: Swedish interview survey of living conditions comprising a random sample of the adult Swedish population. SUBJECTS: 12,675 people interviewed between 1982 and 1983. MAIN OUTCOME MEASURES: Survival of subjects after controlling for eight confounding variables: age, sex, education level, income, long term disease, social network, smoking, and physical exercise. RESULTS: 6,301 men and 6,374 women were followed up; 533 men and 314 women died during this period. The control variables influenced survival in the expected directions except for social network for men; a significant negative effective was found when the analysis was made separately for men and women. We found an influence on mortality when the eight control variables were controlled for in people who rarely attended events compared with those attending most often, the relative risk being 1.57 (95% confidence interval 1.18 to 2.09). CONCLUSION: Attendance at cultural events may have a positive influence on survival. Long term follow up of large samples with confounders that are well controlled for and with the cultural stimulation more highly specified should be used to try to falsify the hypothesis before experiments start. PMID:8990990

Undernutrition as independent predictor of early mortality in elderly cancer patients.

PubMed

Martucci, Renata B; Barbosa, Mariana V; D'Almeida, Cristiane A; Rodrigues, Viviane D; Bergmann, Anke; de Pinho, Nivaldo B; Thuler, Luiz Claudio S

2017-02-01

The aim of this study was to evaluate the 1-y survival of elderly patients with cancer and the association between undernutrition and mortality. This was a cohort study with elderly patients ages ≥65 y admitted between September and October 2014. A nutritionist performed a Mini Nutritional Assessment-Short Form (MNA-SF) assessment during 48 h of hospital admission and collected data about potential confounding variables (comorbidities, stage of cancer, treatment in the previous 3 mo, and reason for hospitalization). Vital status was determined from the medical records or public records office. Overall survival was estimated using the Kaplan-Meier method. Cox regression was performed to estimate unadjusted hazard ratios. Variables with P < 0.20 by univariate analysis were selected for multivariate analysis. P < 0.05 was considered statistically significant. Of the 136 patients (mean age, 73.1 y; 52.2% men), 29.4%, 41.2%, and 29.4% were classified as normal, at risk for undernutrition, and undernutrition, respectively, according to the MNA-SF. The mortality rate was 31.6% after 12 mo. One-year mortality was higher among the undernourished patients, followed by patients at risk for undernutrition. After adjustment for confounding variables, the multivariate regression Cox model showed that being undernourished according to the MNA-SF increased the risk for death at 1 y (hazard ratio, 5.59; 95% confidence interval, 1.8-17.3; P < 0.001). The results showed that the MNA-SF can be a useful tool in identifying elderly patients at higher risk for 1-y mortality. Copyright © 2016 Elsevier Inc. All rights reserved.

Epidemiological survey of oral lesions in children and adolescents in a Brazilian population.

PubMed

Pessôa, Camila Porto; Alves, Técia Daltro Borges; dos Santos, Nilton César Nogueira; dos Santos, Heloísa Laís Rosário; Azevedo, Alana de Cássia Silva; dos Santos, Jean Nunes; Oliveira, Márcio Campos

2015-11-01

To identify the most frequent oral lesions in children and adolescents in Reference Units of Oral Lesions of Public Universities of Bahia, Brazil, in the period between 1996 and 2010, and estimate the association between socio-demographic factors and type of oral lesions found. Cross-sectional study using secondary data obtained from medical records, records of requests and reports of biopsies from patients aged between 0 and 19 years treated in Reference Units of Oral Lesions of Public Universities in Bahia, Brazil, in the period between 1996 and 2010. For data analysis, we used descriptive analysis of the variables, bivariate analysis by calculating the prevalence ratios (PR) to assess the association between oral lesions and gender, age and skin color, and the analysis of potential modifying and confounding effects by logistic regression modeling. To calculate the p-value of associations, we used the chi-square test, and p<0.05 was considered statistically significant. There were 360 records of patients between 0 and 19 years (8.7% of total records). The results revealed 72 different types of lesions. The most prevalent lesions were mucoceles (14.2%), fibroma (5.6%) and pyogenic granuloma (5.3%). The variable "age" was the only socio-demographic characteristics among those analyzed that showed a statistically significant association with both neoplastic and non-neoplastic lesions, according to bivariate analysis, considering the rates adjusted for potential confounders. Neoplastic lesions appeared more often in the age group 0-9 years, while the non-neoplastic lesions were more prevalent in individuals 10-19 years. There was no effect modification noted in the predictive models analyzed. The study identified the existence of a broad range of oral lesions affecting children and adolescents. Most of the lesions found were of the non-neoplastic type. The age of individuals was associated with the type of oral lesion found. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Long term effects of traffic noise on mortality in the city of Barcelona, 2004-2007.

PubMed

Barceló, Maria Antònia; Varga, Diego; Tobias, Aurelio; Diaz, Julio; Linares, Cristina; Saez, Marc

2016-05-01

Numerous studies showing statistically significant associations between environmental noise and adverse health effects already exist for short-term (over one day at most) and long-term (over a year or more) noise exposure, both for morbidity and (albeit to a lesser extent) mortality. Recently, several studies have shown this association to be independent from confounders, mainly those of air pollutants. However, what has not been addressed is the problem of misalignment (i.e. the exposure data locations and health outcomes have different spatial locations). Without any explicit control of such misalignment inference is seriously compromised. Our objective is to assess the long-term effects of traffic noise on mortality in the city of Barcelona (Spain) during 2004-2007. We take into account the control of confounding, for both air pollution and socioeconomic factors at a contextual level and, in particular, we explicitly address the problem of misalignment. We employed a case-control design with individual data. We used deaths resulting from myocardial infarction, hypertension, or Type II diabetes mellitus in Barcelona between 2004 and 2007 as cases for the study, while for controls we used deaths (likewise in Barcelona and over the same period of time) resulting from AIDS or external causes (e.g. accidental falls, accidental poisoning by psychotropic drugs, drugs of abuse, suicide and self-harm, or injuries resulting from motor vehicle accidents). The controls were matched with the cases by sex and age. We used the annual average equivalent A-weighted sound pressure levels for daytime (7-21h), evening-time (21-23h) and night-time (23-7h), and controlled for the following confounders: i) air pollutants (NO2, PM10 and benzene), ii) material deprivation (at a census tract level) and iii) land use and other spatial variables. We explicitly controlled for heterogeneity (uneven distribution of both response and environmental exposures within an area), spatial dependency (of the observations of the response variables), temporal trends (long-term behaviour of the response variables) and spatial misalignment (between response and environmental exposure locations). We used a fully Bayesian method, through the Integrated Nested Laplace Approximation (INLA). Specifically, we plugged the whole model for the exposure into the health model and obtained a linear predictor defined on the entire spatial domain. Separate analyses were carried out for men and for women. After adjusting for confounders, we found that traffic noise was associated with myocardial infarction mortality along with Type II diabetes mellitus in men (in both cases, odds ratios (OR) were around 1.02) and mortality from hypertension in women (ORs around 1.01). Nevertheless, only in the case of hypertension in women, does the association remain statistically significant for all age groups considered (all ages, ≥65 years and ≥75 years). Copyright © 2016 Elsevier Inc. All rights reserved.

Factors Associated with Hepatitis C Knowledge Before and After an Educational Intervention among Vietnamese Americans

PubMed Central

Lee, Sunmin; Zhai, Shumenghui; Zhang, Guo (Yolanda); Ma, Xiang S; Lu, Xiaoxiao; Tan, Yin; Siu, Philip; Seals, Brenda; Ma, Grace X

2015-01-01

BACKGROUND Hepatitis C virus (HCV) is a major cause of chronic liver disease and cancer. Vietnamese Americans are at high risk of HCV infection, with men having the highest US incidence of liver cancer. This study examines an intervention to improve HCV knowledge among Vietnamese Americans. STUDY Seven Vietnamese community-based organizations in Pennsylvania and New Jersey recruited a total of 306 Vietnamese participants from 2010 to 2011. RESULTS Average knowledge scores for pretest and posttest were 3.32 and 5.88, respectively (maximum 10). After adjusting for confounding variables, age and higher education were positively associated with higher pretest scores and having a physician who spoke English or Vietnamese was negatively associated with higher pretest scores. Additionally, after adjusting for confounding variables, household income, education, and having an HCV-infected family member significantly increased knowledge scores. CONCLUSIONS Promotion and development of HCV educational programs can increase HCV knowledge among race and ethnic groups, such as Vietnamese Americans. Giving timely information to at-risk groups provides the opportunity to correct misconceptions, decrease HCV risk behaviors, and encourage testing that might improve timely HCV diagnosis and treatment. PMID:26561280

Towards an understanding of the relationship of functional literacy and numeracy to geographical health inequalities.

PubMed

Moon, Graham; Aitken, Grant; Roderick, Paul; Fraser, Simon; Rowlands, Gill

2015-10-01

The relative contributions of functional literacy and functional numeracy to health disparities remain poorly understood in developed world contexts. We seek to unpack their distinctive contributions and to examine how these contributions are framed by place-based deprivation and rurality. We present a multilevel logistic analysis of the 2011 Skills for Life Survey (SfLS), a representative governmental survey of adults aged 16-65 in England. Outcome measures were self-assessed health status and the presence of self-reported long-term health conditions. Exposure variables were functional literacy (FL) and functional numeracy (FN). Age, sex, individual socio-economic status, ethnicity, whether English was a first language, non-UK birthplaces, housing tenure and geography were included as potential confounders and mediators. Geography was measured as area-based deprivation and urban/rural status. FL and FN were both independently associated with self-assessed health status, though the association attenuated after taking account of confounders and mediators. For long-term conditions, the association with FN remained significant following inclusion of confounders and mediators whilst FL attenuated to non-significance. Rurality did not influence these associations. Area deprivation was a significant factor in attenuating the association between FL and self-assessed health status. Policy makers and health professionals will need to be aware of the distinctive impact of FN as well as FL when combating health inequalities, promoting health and managing long-term conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influences of physical fitness on bone mass in women with fibromyalgia.

PubMed

Gómez-Cabello, Alba; Vicente-Rodríguez, Germán; Navarro-Vera, Isabel; Martinez-Redondo, Diana; Díez-Sánchez, Carmen; Casajús, José Antonio

2015-04-01

The aim of this study was to provide information about the relationship of bone mineral content (BMC) and density (BMD) with some physical-fitness-related variables in a sample of women with fibromyalgia (FM) and age-matched women without FM. Twenty-eight women clinically diagnosed with FM (age 51.1 ± 8.4 yr, M ± SD) and 22 age-matched controls participated in the study. Whole-body BMC and BMD, lean mass, handgrip strength, quadriceps strength, and cardiovascular fitness were measured in all participants. The association between physical-fitness variables and bone-related variables was tested by linear regression controlling for body weight as a possible confounder. There were no differences in BMC or BMD between groups. Women with FM had lower values of handgrip strength, quadriceps strength, and VO2peak than the control group. Handgrip strength and aerobic capacity were associated with BMC and BMD and quadriceps strength was associated with BMD in women with FM; however, only VO2peak was associated with BMC in the group of women without FM. Bone mass of women with FM may be more susceptible to changes in physical fitness than that of the women without fibromyalgia.

Bayesian effect estimation accounting for adjustment uncertainty.

PubMed

Wang, Chi; Parmigiani, Giovanni; Dominici, Francesca

2012-09-01

Model-based estimation of the effect of an exposure on an outcome is generally sensitive to the choice of which confounding factors are included in the model. We propose a new approach, which we call Bayesian adjustment for confounding (BAC), to estimate the effect of an exposure of interest on the outcome, while accounting for the uncertainty in the choice of confounders. Our approach is based on specifying two models: (1) the outcome as a function of the exposure and the potential confounders (the outcome model); and (2) the exposure as a function of the potential confounders (the exposure model). We consider Bayesian variable selection on both models and link the two by introducing a dependence parameter, ω, denoting the prior odds of including a predictor in the outcome model, given that the same predictor is in the exposure model. In the absence of dependence (ω= 1), BAC reduces to traditional Bayesian model averaging (BMA). In simulation studies, we show that BAC, with ω > 1, estimates the exposure effect with smaller bias than traditional BMA, and improved coverage. We, then, compare BAC, a recent approach of Crainiceanu, Dominici, and Parmigiani (2008, Biometrika 95, 635-651), and traditional BMA in a time series data set of hospital admissions, air pollution levels, and weather variables in Nassau, NY for the period 1999-2005. Using each approach, we estimate the short-term effects of on emergency admissions for cardiovascular diseases, accounting for confounding. This application illustrates the potentially significant pitfalls of misusing variable selection methods in the context of adjustment uncertainty. © 2012, The International Biometric Society.

Parental concerns, socioeconomic status, and the risk of autism spectrum conditions in a population-based study.

PubMed

Sun, Xiang; Allison, Carrie; Auyeung, Bonnie; Baron-Cohen, Simon; Brayne, Carol

2014-12-01

A total number of 11,635 screening packs were distributed to 5-10 year-old children in 136 schools in Cambridgeshire to investigate the associations between levels of parental concern (none/minor/strong), socioeconomic status and the risk of having Autism Spectrum Conditions (ASC). The variables for investigating associations and possible confounders were extracted for analysis, including parental concern question score, SES, age of the child, sex, maternal age at birth, paternal age at birth, mother's age of leaving education, father's age of leaving education, birth order and the number of children in the family. The SES, age of the child, sex and mother's age at leaving education were associated with parental concern. Parents with higher SES reported higher levels of concern (Chi-square = 11.8; p = 0.02). However, a higher SES was not associated with the risk of having ASC (p = 0.50). After adjusting for potential confounders, the odds of children meeting ASC criteria whose parents had reported strong parental concern were 8.5 times (odds ratio: 8.5; 95%CI: 4.5, 16.2; p < 0.001) the odds of children having ASC whose parents reported minor concern. No child met ASC criteria where parents expressed no concerns. Parents with higher social class express more concerns than those from lower social classes. However, the concerns reported by parents in higher SES did not appear to be specific for ASC as there was no relationship between ASC and SES. Copyright © 2014 Elsevier Ltd. All rights reserved.

Combating Unmeasured Confounding in Cross-Sectional Studies: Evaluating Instrumental-Variable and Heckman Selection Models

PubMed Central

DeMaris, Alfred

2014-01-01

Unmeasured confounding is the principal threat to unbiased estimation of treatment “effects” (i.e., regression parameters for binary regressors) in nonexperimental research. It refers to unmeasured characteristics of individuals that lead them both to be in a particular “treatment” category and to register higher or lower values than others on a response variable. In this article, I introduce readers to 2 econometric techniques designed to control the problem, with a particular emphasis on the Heckman selection model (HSM). Both techniques can be used with only cross-sectional data. Using a Monte Carlo experiment, I compare the performance of instrumental-variable regression (IVR) and HSM to that of ordinary least squares (OLS) under conditions with treatment and unmeasured confounding both present and absent. I find HSM generally to outperform IVR with respect to mean-square-error of treatment estimates, as well as power for detecting either a treatment effect or unobserved confounding. However, both HSM and IVR require a large sample to be fully effective. The use of HSM and IVR in tandem with OLS to untangle unobserved confounding bias in cross-sectional data is further demonstrated with an empirical application. Using data from the 2006–2010 General Social Survey (National Opinion Research Center, 2014), I examine the association between being married and subjective well-being. PMID:25110904

Insomnia Severity, Subjective Sleep Quality, and Risk for Obstructive Sleep Apnea in Veterans With Gulf War Illness.

PubMed

Chao, Linda L; Abadjian, Linda R; Esparza, Iva L; Reeb, Rosemary

2016-09-01

Despite the fact that sleep disturbances are common in veterans with Gulf War Illness (GWI), there has been a paucity of published sleep studies in this veteran population to date. Therefore, the present study examined subjective sleep quality (assessed with the Pittsburgh Sleep Quality Index), insomnia severity (assessed with the Insomnia Severity Index), and risk for obstructive sleep apnea (assessed with the STOP questionnaire) in 98 Gulf War veterans. Veterans with GWI, defined either by the Kansas or Centers for Disease Control and Prevention criteria, had greater risk for obstructive sleep apnea (i.e., higher STOP scores) than veterans without GWI. This difference persisted even after accounting for potentially confounding demographic (e.g., age, gender) and clinical variables. Veterans with GWI, defined by either the Kansas or Centers for Disease Control and Prevention criteria, also had significantly greater insomnia severity and poorer sleep quality than veterans without GWI (p < 0.05), even after accounting for potentially confounding variables. Furthermore, there were significant, positive correlations between insomnia severity, subjective sleep quality, and GWI symptom severity (p ≤ 0.01). In stepwise linear regression models, insomnia severity significantly predicted GWI status over and above demographic and clinical variables. Together these findings provide good rationale for treating sleep disturbances in the management of GWI. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Coping strategies and quality of life in caregivers of dependent elderly relatives.

PubMed

Rodríguez-Pérez, Margarita; Abreu-Sánchez, Ana; Rojas-Ocaña, María Jesús; Del-Pino-Casado, Rafael

2017-04-14

Despite the importance of coping in caregiving, there are few studies on the relationship between coping and quality of life in caregivers of the frail dependent elderly. Thus, this study aims to analyze the relationship between coping strategies and quality of life dimensions in primary caregivers of dependent elderly relatives. A cross-sectional study was conducted from 86 caregivers. Predictive variables were coping strategies (problem-focused, emotion-focused, socially-supported, and dysfunctional); dependent variables were quality of life dimensions (psychological, physical, relational, and environmental); and potential confounding variables were age, gender, perceived health and burden of caregiver, and functional capacity of care receiver. Correlation coefficients were calculated and multiple linear regression analysis was performed. After controlling for potential confounders, dysfunctional coping was related to worse quality of life in the psychological dimension, while emotion-focused and socially-supported coping were related to superior psychological and environmental dimensions of quality of life. The physical and relational dimensions of quality of life were not related to coping strategies. 1) it is important to consider coping strategies in the assessment of primary caregivers of dependent elderly relatives; 2) the quality of life of caregivers is related to their coping strategies, 3) their quality of life can be worsened by avoidance-type coping, and 4) their quality of life can be improved by active emotion-focused coping and socially-supported coping.

High neuroticism at age 20 predicts history of mental disorders and low self-esteem at age 35.

PubMed

Lönnqvist, Jan-Erik; Verkasalo, Markku; Mäkinen, Seppo; Henriksson, Markus

2009-07-01

The authors assessed whether neuroticism in emerging adulthood predicts mental disorders and self-esteem in early adulthood after controlling for possible confounding variables. A sample of 69 male military conscripts was initially assessed at age 20 and again as civilians at age 35. The initial assessment included a psychiatric interview, objective indicators of conscript competence, an intellectual performance test, and neuroticism questionnaires. The follow-up assessment included a Structured Clinical Interview for DSM-IV (SCID; First, Spitzer, Gibbon, & Williams, 1996) and the Rosenberg Self-Esteem Scale (Rosenberg, 1965). Neuroticism predicted future mental disorders and low self-esteem beyond more objective indicators of adjustment. The results support the use of neuroticism as a predictor of future mental disorders, even over periods of time when personality is subject to change.

Instrumental variables as bias amplifiers with general outcome and confounding.

PubMed

Ding, P; VanderWeele, T J; Robins, J M

2017-06-01

Drawing causal inference with observational studies is the central pillar of many disciplines. One sufficient condition for identifying the causal effect is that the treatment-outcome relationship is unconfounded conditional on the observed covariates. It is often believed that the more covariates we condition on, the more plausible this unconfoundedness assumption is. This belief has had a huge impact on practical causal inference, suggesting that we should adjust for all pretreatment covariates. However, when there is unmeasured confounding between the treatment and outcome, estimators adjusting for some pretreatment covariate might have greater bias than estimators without adjusting for this covariate. This kind of covariate is called a bias amplifier, and includes instrumental variables that are independent of the confounder, and affect the outcome only through the treatment. Previously, theoretical results for this phenomenon have been established only for linear models. We fill in this gap in the literature by providing a general theory, showing that this phenomenon happens under a wide class of models satisfying certain monotonicity assumptions. We further show that when the treatment follows an additive or multiplicative model conditional on the instrumental variable and the confounder, these monotonicity assumptions can be interpreted as the signs of the arrows of the causal diagrams.

Adolescent Support Seeking as a Path to Adult Functional Independence

PubMed Central

Szwedo, David E.; Hessel, Elenda T.; Loeb, Emily L.; Hafen, Christopher A.; Allen, Joseph P.

2017-01-01

The potential importance of depending on others during adolescence in order to establish independence in young adulthood was examined across adolescence to emerging adulthood. Participants included 184 teens (46% male; 42% non-White), their mothers, best friends, and romantic partners, assessed at ages 13–14, 18, 21–22, and 25. Path analyses showed that associations were both partner and age specific: markers of independence were predicted by participants’ efforts to seek support from mothers at age 13, best friends at 18, and romantic partners at 21. Importantly, analyses controlled for support seeking from these partners at other ages, as well as for other potentially confounding variables including attachment security, scholastic/job competence, and physical attractiveness over time. Moreover, analyses suggested the transfer of support seeking behavior from mothers to best friends to romantic partners over time based on support given by the previous partner at an earlier age. PMID:28358534

Poppers, Kaposi's sarcoma, and HIV infection: empirical example of a strong confounding effect?

PubMed

Morabia, A

1995-01-01

Are there empirical examples of strong confounding effects? Textbooks usually show examples of weak confounding or use hypothetical examples of strong confounding to illustrate the paradoxical consequences of not separating out the effect of the studied exposure from that of second factor acting as a confounder. HIV infection is a candidate strong confounder of the spuriously high association reported between consumption of poppers, a sexual stimulant, and risk of Kaposi's sarcoma in the early phase of the AIDS epidemic. To examine this hypothesis, assumptions must be made on the prevalence of HIV infection among cases of Kaposi's sarcoma and on the prevalence of heavy popper consumption according to HIV infection in cases and controls. Results show that HIV infection may have confounded the poppers-Kaposi's sarcoma association. However, it cannot be ruled out that HIV did not qualify as a confounder because it was either an intermediate variable or an effect modifier of the association between popper inhalation and Kaposi's sarcoma. This example provides a basis to discuss the mechanism by which confounding occurs as well as the practical importance of confounding in epidemiologic research.

The Effect of Serum Sodium on Survival in Patients Treated by Peritoneal Dialysis in the United Kingdom.

PubMed

Al-Chidadi, Asmaa; Nitsch, Dorothea; Davenport, Andrew

♦ BACKGROUND: Studies in hemodialysis patients suggest that hyponatremia is associated with increased mortality. However, results from peritoneal dialysis (PD) patients are discordant. We wished to establish whether there was an association between serum sodium and mortality risk in PD patients. ♦ METHODS: We analyzed 3,108 PD patients enrolled at day 90 of renal replacement therapy (RRT) into the UK Renal Registry (UKRR) data base with available serum sodium measurements (in 3 groups: ≤ 137, 138 - 140, ≥ 141 mmol/L) who were then followed up until death or the censoring date (31 December 2012). Analysis used Cox-regression with adjustment for age, sex, year of starting RRT, primary renal disease, serum albumin, smoking, and comorbidities. ♦ RESULTS: Unadjusted mortality rates were 118.6/1,000 person-years (py), 83.4/1,000 py, and 83.5/1,000 py for the lowest, middle, and highest serum sodium tertiles, respectively. After adjustment for covariates, patients in the lowest serum sodium group had almost 50% increased risk of dying compared with those with the highest serum sodium (hazard ratio [HR] 1.49, confidence interval [CI]:1.28 - 1.74), with a graded association between serum sodium and mortality. The association of serum sodium with mortality varied by age (p interaction < 0.001), and whilst this association attenuated after adjustment for confounding variables in the older age groups (55 - 64, and > 65 years), it remained in the younger age group of 18 - 54 years (HR 2.24 [1.36 - 3.70] in the lowest compared with the highest sodium tertile). ♦ CONCLUSIONS: Lower serum sodium concentrations at the start of RRT in PD patients are associated with increased risk of mortality. Whilst this association may well be due to confounding in the older age groups, the persistent strong association between hyponatremia and mortality in the younger age group after adjustment for the available confounders suggests that prospective studies are required to assess whether active intervention to maintain serum sodium changes outcomes. Copyright © 2017 International Society for Peritoneal Dialysis.

Mechanisms of PD-L1/PD-1-mediated CD8 T-cell dysfunction in the context of aging-related immune defects in the Eµ-TCL1 CLL mouse model.

PubMed

McClanahan, Fabienne; Riches, John C; Miller, Shaun; Day, William P; Kotsiou, Eleni; Neuberg, Donna; Croce, Carlo M; Capasso, Melania; Gribben, John G

2015-07-09

T-cell defects, immune suppression, and poor antitumor immune responses are hallmarks of chronic lymphocytic leukemia (CLL), and PD-1/PD-L1 inhibitory signaling has emerged as a major immunosuppressive mechanism. However, the effect of different microenvironments and the confounding influence of aging are poorly understood. The current study uses the Eμ-TCL1 mouse model, which replicates human T-cell defects, as a preclinical platform to longitudinally examine patterns of T-cell dysfunction alongside developing CLL and in different microenvironments, with a focus on PD-1/PD-L1 interactions. The development of CLL was significantly associated with changes in T-cell phenotype across all organs and function. Although partly mirrored in aging wild-type mice, CLL-specific T-cell changes were identified. Murine CLL cells highly expressed PD-L1 and PD-L2 in all organs, with high PD-L1 expression in the spleen. CD3(+)CD8(+) T cells from leukemic and aging healthy mice highly expressed PD-1, identifying aging as a confounder, but adoptive transfer experiments demonstrated CLL-specific PD-1 induction. Direct comparisons of PD-1 expression and function between aging CLL mice and controls identified PD-1(+) T cells in CLL as a heterogeneous population with variable effector function. This is highly relevant for therapeutic targeting of CD8(+) T cells, showing the potential of reprogramming and selective subset expansion to restore antitumor immunity. © 2015 by The American Society of Hematology.

Mechanisms of PD-L1/PD-1–mediated CD8 T-cell dysfunction in the context of aging-related immune defects in the Eµ-TCL1 CLL mouse model

PubMed Central

McClanahan, Fabienne; Riches, John C.; Miller, Shaun; Day, William P.; Kotsiou, Eleni; Neuberg, Donna; Croce, Carlo M.; Capasso, Melania

2015-01-01

T-cell defects, immune suppression, and poor antitumor immune responses are hallmarks of chronic lymphocytic leukemia (CLL), and PD-1/PD-L1 inhibitory signaling has emerged as a major immunosuppressive mechanism. However, the effect of different microenvironments and the confounding influence of aging are poorly understood. The current study uses the Eμ-TCL1 mouse model, which replicates human T-cell defects, as a preclinical platform to longitudinally examine patterns of T-cell dysfunction alongside developing CLL and in different microenvironments, with a focus on PD-1/PD-L1 interactions. The development of CLL was significantly associated with changes in T-cell phenotype across all organs and function. Although partly mirrored in aging wild-type mice, CLL-specific T-cell changes were identified. Murine CLL cells highly expressed PD-L1 and PD-L2 in all organs, with high PD-L1 expression in the spleen. CD3+CD8+ T cells from leukemic and aging healthy mice highly expressed PD-1, identifying aging as a confounder, but adoptive transfer experiments demonstrated CLL-specific PD-1 induction. Direct comparisons of PD-1 expression and function between aging CLL mice and controls identified PD-1+ T cells in CLL as a heterogeneous population with variable effector function. This is highly relevant for therapeutic targeting of CD8+ T cells, showing the potential of reprogramming and selective subset expansion to restore antitumor immunity. PMID:25979947

Clinical correlates of enlarged cavum septum pellucidum in schizophrenia: A revisit through computed tomography.

PubMed

Srivastava, Naveen Kumar; Khanra, Sourav; Chail, Vivek; Khess, Christoday R J

2015-06-01

Like prevalence of abnormal cavum septum pellucidum in patients of schizophrenia remains controversial, its role in clinical outcome, duration of illness and effect on treatment remains less understood as well. Our study examined clinical correlates of enlarged cavum septum pellucidum in schizophrenia. A total of 139 patients diagnosed with schizophrenia during the year 2012 and 2013 were taken for the study. We compared them in respect to the presence and absence of enlarged cavum septum pellucidum. We found 16 patients with enlarged cavum septum pellucidum and were compared with those without enlarged cavum septum pellucidum for socio-demographic and clinical variables. We also correlated these clinical variables with dimension of cavum septum pellucidum. We found statistically significant increased current age and duration of illness in patients with enlarged cavum septum pellucidum. The implications of these findings are discussed with possible confounding effect of current age on neuroimaging. No meaningful correlation was found. No difference in clinical variables was found. Retrospective design and use of computed tomography were limitation of our study. Copyright © 2015 Elsevier B.V. All rights reserved.

Oral contraceptive use and female genital arousal: methodological considerations.

PubMed

Seal, Brooke N; Brotto, Lori A; Gorzalka, Boris B

2005-08-01

This study explored effects of oral contraceptive pill (OCP) use on physiological sexual arousal as measured by a vaginal photoplethysmograph. Sixteen women aged 18-29 viewed audiovisual neutral and erotic stimuli before and an average of 6 weeks following the onset of OCP use. Although subjective measures of sexual arousal, including perceptions of genital arousal, significantly increased in response to erotic stimuli both before and after OCP onset, physiological sexual arousal only increased before OCP use. A comparison of individual responses before and after OCP onset reveals a much higher degree of intrasubject variability after OCP onset. We discuss these findings as they relate to OCP use as a confounding methodological variable to consider in future investigations employing vaginal photoplethysmography.

Analyzing partially missing confounder information in comparative effectiveness and safety research of therapeutics.

PubMed

Toh, Sengwee; García Rodríguez, Luis A; Hernán, Miguel A

2012-05-01

Electronic healthcare databases are commonly used in comparative effectiveness and safety research of therapeutics. Many databases now include additional confounder information in a subset of the study population through data linkage or data collection. We described and compared existing methods for analyzing such datasets. Using data from The Health Improvement Network and the relation between non-steroidal anti-inflammatory drugs and upper gastrointestinal bleeding as an example, we employed several methods to handle partially missing confounder information. The crude odds ratio (OR) of upper gastrointestinal bleeding was 1.50 (95% confidence interval: 0.98, 2.28) among selective cyclo-oxygenase-2 inhibitor initiators (n = 43 569) compared with traditional non-steroidal anti-inflammatory drug initiators (n = 411 616). The OR dropped to 0.81 (0.52, 1.27) upon adjustment for confounders recorded for all patients. When further considering three additional variables missing in 22% of the study population (smoking, alcohol consumption, body mass index), the OR was between 0.80 and 0.83 for the missing-category approach, the missing-indicator approach, single imputation by the most common category, multiple imputation by chained equations, and propensity score calibration. The OR was 0.65 (0.39, 1.09) and 0.67 (0.38, 1.16) for the unweighted and the inverse probability weighted complete-case analysis, respectively. Existing methods for handling partially missing confounder data require different assumptions and may produce different results. The unweighted complete-case analysis, the missing-category/indicator approach, and single imputation require often unrealistic assumptions and should be avoided. In this study, differences across methods were not substantial, likely due to relatively low proportion of missingness and weak confounding effect by the three additional variables upon adjustment for other variables. Copyright © 2012 John Wiley & Sons, Ltd.

The Influence of Social Interaction and Physical Health on the Association Between Hearing and Depression With Age and Gender

PubMed Central

Seeto, Mark

2017-01-01

Recent epidemiological data suggest the relation between hearing difficulty and depression is more evident in younger and middle-aged populations than in older adults. There are also suggestions that the relation may be more evident in specific subgroups; that is, other factors may influence a relationship between hearing and depression in different subgroups. Using cross-sectional data from the UK Biobank on 134,357 community-dwelling people and structural equation modelling, this study examined the potential mediating influence of social isolation and unemployment and the confounding influence of physical illness and cardiovascular conditions on the relation between a latent hearing variable and both a latent depressive episodes variable and a latent depressive symptoms variable. The models were stratified by age (40s, 50s, and 60s) and gender and further controlled for physical illness and professional support in associations involving social isolation and unemployment. The latent hearing variable was primarily defined by reported hearing difficulty in noise. For all subgroups, poor hearing was significantly related to both more depressive episodes and more depressive symptoms. In all models, the direct and generally small association exceeded the indirect associations via physical health and social interaction. Significant (depressive episodes) and near significant (depressive symptoms) higher direct associations were estimated for males in their 40s and 50s than for males in their 60s. There was at each age-group no significant difference in estimated associations across gender. Irrespective of the temporal order of variables, findings suggest that audiological services should facilitate psychosocial counselling. PMID:28752806

The Influence of Social Interaction and Physical Health on the Association Between Hearing and Depression With Age and Gender.

PubMed

Keidser, Gitte; Seeto, Mark

2017-01-01

Recent epidemiological data suggest the relation between hearing difficulty and depression is more evident in younger and middle-aged populations than in older adults. There are also suggestions that the relation may be more evident in specific subgroups; that is, other factors may influence a relationship between hearing and depression in different subgroups. Using cross-sectional data from the UK Biobank on 134,357 community-dwelling people and structural equation modelling, this study examined the potential mediating influence of social isolation and unemployment and the confounding influence of physical illness and cardiovascular conditions on the relation between a latent hearing variable and both a latent depressive episodes variable and a latent depressive symptoms variable. The models were stratified by age (40s, 50s, and 60s) and gender and further controlled for physical illness and professional support in associations involving social isolation and unemployment. The latent hearing variable was primarily defined by reported hearing difficulty in noise. For all subgroups, poor hearing was significantly related to both more depressive episodes and more depressive symptoms. In all models, the direct and generally small association exceeded the indirect associations via physical health and social interaction. Significant (depressive episodes) and near significant (depressive symptoms) higher direct associations were estimated for males in their 40s and 50s than for males in their 60s. There was at each age-group no significant difference in estimated associations across gender. Irrespective of the temporal order of variables, findings suggest that audiological services should facilitate psychosocial counselling.

The Association of Dietary l-Arginine Intake and Serum Nitric Oxide Metabolites in Adults: A Population-Based Study

PubMed Central

Mirmiran, Parvin; Bahadoran, Zahra; Ghasemi, Asghar; Azizi, Fereidoun

2016-01-01

This study was conducted to investigate whether regular dietary intake of l-arginine is associated with serum nitrate + nitrite (NOx). In this cross-sectional study, 2771 men and women, who had participated in the third examination of the Tehran Lipid and Glucose Study (2006–2008), were recruited. Demographics, anthropometrics and biochemical variables were evaluated. Dietary data were collected using a validated 168-food item semi-quantitative food frequency questionnaire and dietary intake of l-arginine was calculated. To determine any association between dietary l-arginine and serum NOx, linear regression models with adjustment for potential confounders were used. Mean age of participants (39.2% men) was 45.9 ± 15.9 years. After adjustment for all potential confounding variables, a significant positive association was observed between l-arginine intake and serum NOx concentrations in the fourth quartile of l-arginine (β = 6.63, 95% CI = 4.14, 9.12, p for trend = 0.001), an association stronger in women. Further analysis, stratified by age, body mass index and hypertension status categories, showed a greater association in middle-aged and older adults (β = 9.12, 95% CI = 3.99, 13.6 and β = 12.1, 95% CI = 6.48, 17.7, respectively). l-arginine intakes were also strongly associated with serum NOx levels in overweight and obese subjects in the upper quartile (β = 10.7, 95% CI = 5.43, 16.0 and β = 11.0, 95% CI = 4.29, 17.5); a greater association was also observed between l-arginine intakes and serum NOx in non-hypertensive (HTN) compared to HTN subjects (β = 2.65, 95% CI = 2.1–3.2 vs. β = 1.25, 95% CI = −1.64–4.15). Dietary l-arginine intakes were associated to serum NOx and this association may be affected by sex, age, body mass index, and hypertension status. PMID:27213443

Periodontitis is associated with diabetic retinopathy in non-obese adults.

PubMed

Song, Su Jeong; Lee, Seong-Su; Han, Kyungdo; Park, Jun-Beom

2017-04-01

Patients with diabetes retinopathy appear to show increased susceptibility to periodontal disease. This study was performed to assess the relationship between periodontitis and the prevalence of diabetic retinopathy in a large probability sample of the Korean population. A subgroup analysis was performed using body mass index <25 kg/m 2 as the criterion to evaluate the effect of obesity on this relationship. This study is based on data from the Korean National Health and Nutrition Examination Survey of the Korean population, conducted between 2008 and 2010. The presence of diabetic retinopathy in relation to demographic variables and anthropometric characteristics of the participants is presented as means with their standard errors. The presence of periodontitis and presence of retinopathy categorized by body mass index (<25 and ≥25 kg/m 2 ) were evaluated. Multiple logistic regression analyses were used to assess the associations between periodontitis and diabetic retinopathy after adjustment with variables, including age, sex, smoking, drinking, exercise, hypertension, metabolic syndrome, HbA1c, and duration of diabetes mellitus. There was a statistically significant increase in the prevalence of periodontitis in individuals who had proliferative diabetic retinopathy. The odds ratios [95% confidence intervals] of prevalence of diabetic retinopathy were 1.193 [0.757-1.881] for the whole population after adjustments with confounding factors. Subgroup analysis after adjustments with confounding factors showed that the odds ratios [95% confidence intervals] of prevalence were 2.206 [1.114-4.366] and 0.588 [0.326-1.061] among participants with body mass index <25 kg/m 2 and body mass index 37 ≥25 kg/m 2 , respectively. The diabetic retinopathy was positively associated with the presence of periodontitis in non-obese diabetic Korean adults after adjustment with confounding variables. Our findings suggest that when a periodontist finds the presence of periodontitis in non-obese diabetic patients, timely evaluation of the patient's ophthalmic evaluation should be 44 recommended.

Assessment of the number of eye symptoms and the impact of some confounding variables for office staff in non-air-conditioned buildings.

PubMed

Doughty, Michael J; Blades, Kenneth A; Ibrahim, Nassim

2002-03-01

The goal of this study was both to assess the frequency of self-reported eye symptoms for employees in a non-air-conditioned office building complex, and to specifically assess whether confounding variables (contact lens wear, medicines use, and provoking stimuli) had a discernible impact on the characteristics of this reporting. A questionnaire was distributed, in the winter months, to office employees in a building complex within a city-located University site, consisting of non-air-conditioned rooms with some mechanical ventilation. The questionnaire asked respondents to identify any eye symptoms experienced (foreign body sensation, soreness, dryness, grittiness, itchiness, stinging, intense burning), the frequency of their occurrence, details of any conditions provoking eye symptoms (such as changes in the microenvironment), their medication use and if they were contact lens wearers. The proportion of respondents for various categories was calculated, along with the total number of symptoms. If 'eye irritation' is considered as reporting any symptoms experienced at any time, then 63% of 292 respondents (median age 42.5 years) reported an average of 1.83 symptoms. However, the identification of contact lens wearers, medication use (especially for seasonal allergies) and provoking stimuli reduced this prevalence to just 29% (with the average number of symptoms being 1.51). If the frequency of experiencing symptoms was also taken into account (never, sometimes, often, and constantly), then only 12.3% of the respondents indicated symptoms often or constantly, i.e. could be considered to have significant symptoms. In all categories, men were more likely to report eye symptoms compared with women. The results confirm that office employees are likely to have some ocular symptoms, but that even a simple consideration of possible confounding variables can greatly change the reported prevalence of eye irritation that might be specifically associated with the workplace environment.

Sensitivity analysis for direct and indirect effects in the presence of exposure-induced mediator-outcome confounders

PubMed Central

Chiba, Yasutaka

2014-01-01

Questions of mediation are often of interest in reasoning about mechanisms, and methods have been developed to address these questions. However, these methods make strong assumptions about the absence of confounding. Even if exposure is randomized, there may be mediator-outcome confounding variables. Inference about direct and indirect effects is particularly challenging if these mediator-outcome confounders are affected by the exposure because in this case these effects are not identified irrespective of whether data is available on these exposure-induced mediator-outcome confounders. In this paper, we provide a sensitivity analysis technique for natural direct and indirect effects that is applicable even if there are mediator-outcome confounders affected by the exposure. We give techniques for both the difference and risk ratio scales and compare the technique to other possible approaches. PMID:25580387

Dietary supplement use and smoking are important correlates of biomarkers of water-soluble vitamin status after adjusting for sociodemographic and lifestyle variables in a representative sample of U.S. adults.

PubMed

Pfeiffer, Christine M; Sternberg, Maya R; Schleicher, Rosemary L; Rybak, Michael E

2013-06-01

Biochemical indicators of water-soluble vitamin (WSV) status were measured in a nationally representative sample of the U.S. population in NHANES 2003-2006. To examine whether demographic differentials in nutritional status were related to and confounded by certain variables, we assessed the association of sociodemographic (age, sex, race-ethnicity, education, income) and lifestyle (dietary supplement use, smoking, alcohol consumption, BMI, physical activity) variables with biomarkers of WSV status in adults (aged ≥ 20 y): serum and RBC folate, serum pyridoxal-5'-phosphate (PLP), serum 4-pyridoxic acid, serum total cobalamin (vitamin B-12), plasma total homocysteine (tHcy), plasma methylmalonic acid (MMA), and serum ascorbic acid. Age (except for PLP) and smoking (except for MMA) were generally the strongest significant correlates of these biomarkers (|r| ≤ 0.43) and together with supplement use explained more of the variability compared with the other covariates in bivariate analysis. In multiple regression models, sociodemographic and lifestyle variables together explained from 7 (vitamin B-12) to 29% (tHcy) of the biomarker variability. We observed significant associations for most biomarkers (≥ 6 of 8) with age, sex, race-ethnicity, supplement use, smoking, and BMI and for some biomarkers with PIR (5 of 8), education (1 of 8), alcohol consumption (4 of 8), and physical activity (5 of 8). We noted large estimated percentage changes in biomarker concentrations between race-ethnic groups (from -24 to 20%), between supplement users and nonusers (from -12 to 104%), and between smokers and nonsmokers (from -28 to 8%). In summary, age, sex, and race-ethnic differentials in biomarker concentrations remained significant after adjusting for sociodemographic and lifestyle variables. Supplement use and smoking were important correlates of biomarkers of WSV status.

Divergent marijuana trajectories among men: Socioeconomic, relationship, and life satisfaction outcomes in the mid-30s

PubMed Central

White, Helene R.; Bechtold, Jordan; Loeber, Rolf; Pardini, Dustin

2016-01-01

Background Given recent changes in marijuana policy in the United States, it is important to understand the long-term effects of marijuana use on adult functioning. We examined whether men who displayed different trajectories of marijuana use from adolescence through emerging adulthood (age ~15–26) differed in terms of socioeconomic, social, and life satisfaction outcomes in their mid-30s. Methods Data came from a longitudinal sample of men who were recruited in early adolescence (N = 506) and followed into adulthood. Four trajectory groups based on patterns of marijuana use from adolescence into emerging adulthood were compared on adult outcomes (age ~36) before and after controlling for co-occurring use of other substances and several pre-existing confounding factors in early adolescence. The potential moderating effect of race was also examined. Results Although there were initially group differences across all domains, once pre-existing confounds and co-occurring other substance use were included in the model, groups only differed in terms of partner and friend marijuana use. Chronic marijuana users reported the highest proportions of both. Frequent and persistent marijuana use was associated with lower socioeconomic status (SES) for Black men only. Conclusions After statistically accounting for confounding variables, chronic marijuana users were not at a heightened risk for maladjustment in adulthood except for lower SES among Black men. Chronic users were more likely to have friends and partners who also used marijuana. Future studies should take into account pre-existing differences when examining outcomes of marijuana use. PMID:26365837

Eating frequency in relation to BMI in very young children: a longitudinal analysis.

PubMed

Taylor, Rachael W; Iosua, Ella; Heath, Anne-Louise M; Gray, Andrew R; Taylor, Barry J; Lawrence, Julie A; Hanna, Maha; Cameron, Sonya L; Sayers, Rachel; Galland, Barbara

2017-06-01

Eating less frequently is associated with increased obesity risk in older children but data are potentially confounded by reverse causation, where bigger children eat less often in an effort to control their weight. Longitudinal data, particularly in younger children, are scarce. We aimed to determine whether eating frequency (meals and snacks) at 2 years of age is associated with past, current or subsequent BMI. Cohort analysis of a randomised controlled trial. Eating frequency at 2 years of age was estimated using 48 h diaries that recorded when each child ate meals and snacks (parent-defined) in five-minute blocks. Body length/height and weight were measured at 1, 2 and 3·5 years of age. Linear regression assessed associations between the number of eating occasions and BMI Z-score, before and after adjustment for potential confounding variables. Prevention of Overweight in Infancy (POI) study, Dunedin, New Zealand. Children (n 371) aged 1-3·5 years. On average, children ate 5·5 (sd 1·2) times/d at 2 years of age, with most children (88-89 %) eating 4-7 times/d. Eating frequency at 2 years was not associated with current (difference in BMI Z-score per additional eating occasion; 95 % CI: -0·02; -0·10, 0·05) or subsequent change (0·02; -0·03, 0·06) in BMI. Similarly, BMI at age 1 year did not predict eating frequency at 2 years of age (difference in eating frequency per additional BMI Z-score unit; 95 % CI: -0·03; -0·19, 0·13). Number of eating occasions per day was not associated with BMI in young children in the present study.

Controlling for confounding variables in MS-omics protocol: why modularity matters.

PubMed

Smith, Rob; Ventura, Dan; Prince, John T

2014-09-01

As the field of bioinformatics research continues to grow, more and more novel techniques are proposed to meet new challenges and improvements upon solutions to long-standing problems. These include data processing techniques and wet lab protocol techniques. Although the literature is consistently thorough in experimental detail and variable-controlling rigor for wet lab protocol techniques, bioinformatics techniques tend to be less described and less controlled. As the validation or rejection of hypotheses rests on the experiment's ability to isolate and measure a variable of interest, we urge the importance of reducing confounding variables in bioinformatics techniques during mass spectrometry experimentation. © The Author 2013. Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Assessing mediation using marginal structural models in the presence of confounding and moderation

PubMed Central

Coffman, Donna L.; Zhong, Wei

2012-01-01

This paper presents marginal structural models (MSMs) with inverse propensity weighting (IPW) for assessing mediation. Generally, individuals are not randomly assigned to levels of the mediator. Therefore, confounders of the mediator and outcome may exist that limit causal inferences, a goal of mediation analysis. Either regression adjustment or IPW can be used to take confounding into account, but IPW has several advantages. Regression adjustment of even one confounder of the mediator and outcome that has been influenced by treatment results in biased estimates of the direct effect (i.e., the effect of treatment on the outcome that does not go through the mediator). One advantage of IPW is that it can properly adjust for this type of confounding, assuming there are no unmeasured confounders. Further, we illustrate that IPW estimation provides unbiased estimates of all effects when there is a baseline moderator variable that interacts with the treatment, when there is a baseline moderator variable that interacts with the mediator, and when the treatment interacts with the mediator. IPW estimation also provides unbiased estimates of all effects in the presence of non-randomized treatments. In addition, for testing mediation we propose a test of the null hypothesis of no mediation. Finally, we illustrate this approach with an empirical data set in which the mediator is continuous, as is often the case in psychological research. PMID:22905648

Assessing mediation using marginal structural models in the presence of confounding and moderation.

PubMed

Coffman, Donna L; Zhong, Wei

2012-12-01

This article presents marginal structural models with inverse propensity weighting (IPW) for assessing mediation. Generally, individuals are not randomly assigned to levels of the mediator. Therefore, confounders of the mediator and outcome may exist that limit causal inferences, a goal of mediation analysis. Either regression adjustment or IPW can be used to take confounding into account, but IPW has several advantages. Regression adjustment of even one confounder of the mediator and outcome that has been influenced by treatment results in biased estimates of the direct effect (i.e., the effect of treatment on the outcome that does not go through the mediator). One advantage of IPW is that it can properly adjust for this type of confounding, assuming there are no unmeasured confounders. Further, we illustrate that IPW estimation provides unbiased estimates of all effects when there is a baseline moderator variable that interacts with the treatment, when there is a baseline moderator variable that interacts with the mediator, and when the treatment interacts with the mediator. IPW estimation also provides unbiased estimates of all effects in the presence of nonrandomized treatments. In addition, for testing mediation we propose a test of the null hypothesis of no mediation. Finally, we illustrate this approach with an empirical data set in which the mediator is continuous, as is often the case in psychological research. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Directed acyclic graphs (DAGs): an aid to assess confounding in dental research.

PubMed

Merchant, Anwar T; Pitiphat, Waranuch

2002-12-01

Confounding, a special type of bias, occurs when an extraneous factor is associated with the exposure and independently affects the outcome. In order to get an unbiased estimate of the exposure-outcome relationship, we need to identify potential confounders, collect information on them, design appropriate studies, and adjust for confounding in data analysis. However, it is not always clear which variables to collect information on and adjust for in the analyses. Inappropriate adjustment for confounding can even introduce bias where none existed. Directed acyclic graphs (DAGs) provide a method to select potential confounders and minimize bias in the design and analysis of epidemiological studies. DAGs have been used extensively in expert systems and robotics. Robins (1987) introduced the application of DAGs in epidemiology to overcome shortcomings of traditional methods to control for confounding, especially as they related to unmeasured confounding. DAGs provide a quick and visual way to assess confounding without making parametric assumptions. We introduce DAGs, starting with definitions and rules for basic manipulation, stressing more on applications than theory. We then demonstrate their application in the control of confounding through examples of observational and cross-sectional epidemiological studies.

Sex, Age, and Emotional Valence: Revealing Possible Biases in the 'Reading the Mind in the Eyes' Task.

PubMed

Kynast, Jana; Schroeter, Matthias L

2018-01-01

The 'Reading the Mind in the Eyes' test (RMET) assesses a specific socio-cognitive ability, i.e., the ability to identify mental states from gaze. The development of this ability in a lifespan perspective is of special interest. Whereas former investigations were limited mainly to childhood and adolescence, the focus has been shifted towards aging, and psychiatric and neurodegenerative diseases recently. Although the RMET is frequently applied in developmental psychology and clinical settings, stimulus characteristics have never been investigated with respect to potential effects on test performance. Here, we analyzed the RMET stimulus set with a special focus on interrelations between sex, age and emotional valence. Forty-three persons rated age and emotional valence of the RMET picture set. Differences in emotional valence and age ratings between male and female items were analyzed. The linear relation between age and emotional valence was tested over all items, and separately for male and female items. Male items were rated older and more negative than female stimuli. Regarding male RMET items, age predicted emotional valence: older age was associated with negative emotions. Contrary, age and valence were not linearly related in female pictures. All ratings were independent of rater characteristics. Our results demonstrate a strong confound between sex, age, and emotional valence in the RMET. Male items presented a greater variability in age ratings compared to female items. Age and emotional valence were negatively associated among male items, but no significant association was found among female stimuli. As personal attributes impact social information processing, our results may add a new perspective on the interpretation of previous findings on interindividual differences in RMET accuracy, particularly in the field of developmental psychology, and age-associated neuropsychiatric diseases. A revision of the RMET might be afforded to overcome confounds identified here.

Sex, Age, and Emotional Valence: Revealing Possible Biases in the ‘Reading the Mind in the Eyes’ Task

PubMed Central

Kynast, Jana; Schroeter, Matthias L.

2018-01-01

The ‘Reading the Mind in the Eyes’ test (RMET) assesses a specific socio-cognitive ability, i.e., the ability to identify mental states from gaze. The development of this ability in a lifespan perspective is of special interest. Whereas former investigations were limited mainly to childhood and adolescence, the focus has been shifted towards aging, and psychiatric and neurodegenerative diseases recently. Although the RMET is frequently applied in developmental psychology and clinical settings, stimulus characteristics have never been investigated with respect to potential effects on test performance. Here, we analyzed the RMET stimulus set with a special focus on interrelations between sex, age and emotional valence. Forty-three persons rated age and emotional valence of the RMET picture set. Differences in emotional valence and age ratings between male and female items were analyzed. The linear relation between age and emotional valence was tested over all items, and separately for male and female items. Male items were rated older and more negative than female stimuli. Regarding male RMET items, age predicted emotional valence: older age was associated with negative emotions. Contrary, age and valence were not linearly related in female pictures. All ratings were independent of rater characteristics. Our results demonstrate a strong confound between sex, age, and emotional valence in the RMET. Male items presented a greater variability in age ratings compared to female items. Age and emotional valence were negatively associated among male items, but no significant association was found among female stimuli. As personal attributes impact social information processing, our results may add a new perspective on the interpretation of previous findings on interindividual differences in RMET accuracy, particularly in the field of developmental psychology, and age-associated neuropsychiatric diseases. A revision of the RMET might be afforded to overcome confounds identified here. PMID:29755385

Overcoming ecologic bias using the two-phase study design.

PubMed

Wakefield, Jon; Haneuse, Sebastien J-P A

2008-04-15

Ecologic (aggregate) data are widely available and widely utilized in epidemiologic studies. However, ecologic bias, which arises because aggregate data cannot characterize within-group variability in exposure and confounder variables, can only be removed by supplementing ecologic data with individual-level data. Here the authors describe the two-phase study design as a framework for achieving this objective. In phase 1, outcomes are stratified by any combination of area, confounders, and error-prone (or discretized) versions of exposures of interest. Phase 2 data, sampled within each phase 1 stratum, provide accurate measures of exposure and possibly of additional confounders. The phase 1 aggregate-level data provide a high level of statistical power and a cross-classification by which individuals may be efficiently sampled in phase 2. The phase 2 individual-level data then provide a control for ecologic bias by characterizing the within-area variability in exposures and confounders. In this paper, the authors illustrate the two-phase study design by estimating the association between infant mortality and birth weight in several regions of North Carolina for 2000-2004, controlling for gender and race. This example shows that the two-phase design removes ecologic bias and produces gains in efficiency over the use of case-control data alone. The authors discuss the advantages and disadvantages of the approach.

Association between indoor and outdoor air pollution and adolescent asthma from 1995 to 1996 in Taiwan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, T.N.; Ko, Y.C.; Chao, Y.Y.

The study aim was to estimate the contribution of indoor and outdoor air pollution to the 1-year prevalence of adolescent asthma after personal susceptibility and other potential risk factors were taken into account. A large-scaled cross-sectional study was conducted among 165,173 high school students aged 11 to 16 years in the different communities of Kaohsiung and Pintong in Taiwan, from October 1995 to June 1996. Each student and his/her parents participating in the study completed a video and a written International Study of Asthma and Allergies in Childhood questionnaire about symptoms of wheezing and allergies, passive smoking, and demographic variables.more » After adjustment for potential confounders, adolescents exposed to cigarette smoking and environmental tobacco smoke were found to suffer from asthma at an increased frequency. The authors observed a statistically significant association between outdoor air pollution and asthma, after controlling for potential confound variables. Total suspended particulate, nitrogen dioxide, carbon monoxide, ozone, and airborne dust particles all displayed an independent association with asthma, respectively. There were no selection biases in this community-based study, which provides evidence that passive smoking and long-term, high average outdoor air pollution are independent risk factors of asthma.« less

Adult consequences of growth failure in early childhood123

PubMed Central

Hoddinott, John; Behrman, Jere R; Maluccio, John A; Melgar, Paul; Quisumbing, Agnes R; Ramirez-Zea, Manuel; Stein, Aryeh D; Yount, Kathryn M

2013-01-01

Background: Growth failure is associated with adverse consequences, but studies need to control adequately for confounding. Objective: We related height-for-age z scores (HAZs) and stunting at age 24 mo to adult human capital, marriage, fertility, health, and economic outcomes. Design: In 2002–2004, we collected data from 1338 Guatemalan adults (aged 25–42 y) who were studied as children in 1969–1977. We used instrumental variable regression to correct for estimation bias and adjusted for potentially confounding factors. Results: A 1-SD increase in HAZ was associated with more schooling (0.78 grades) and higher test scores for reading and nonverbal cognitive skills (0.28 and 0.25 SDs, respectively), characteristics of marriage partners (1.39 y older, 1.02 grade more schooling, and 1.01 cm taller) and, for women, a higher age at first birth (0.77 y) and fewer number of pregnancies and children (0.63 and 0.43, respectively). A 1-SD increase in HAZ was associated with increased household per capita expenditure (21%) and a lower probability of living in poverty (10 percentage points). Conversely, being stunted at 2 y was associated with less schooling, a lower test performance, a lower household per capita expenditure, and an increased probability of living in poverty. For women, stunting was associated with a lower age at first birth and higher number of pregnancies and children. There was little relation between either HAZ or stunting and adult health. Conclusion: Growth failure in early life has profound adverse consequences over the life course on human, social, and economic capital. PMID:24004889

Effects of various factors on Doppler ultrasonographic measurements of radial and coccygeal arterial blood pressure in privately owned, conscious cats.

PubMed

Whittemore, Jacqueline C; Nystrom, Michael R; Mawby, Dianne I

2017-04-01

OBJECTIVE To assess the effects of age, body condition score (BCS), and muscle condition score (MCS) on radial and coccygeal systolic arterial blood pressure (SAP) in cats. DESIGN Prospective randomized trial. ANIMALS 66 privately owned cats enrolled between May and December 2010. PROCEDURES BCS and MCS of cats were assessed by 2 investigators; SAP was measured via Doppler ultrasonic flow detector, with cats positioned in right lateral or sternal recumbency for measurements at the radial or coccygeal artery, respectively, with order of site randomized. Associations among variables were assessed through correlation coefficients, partial correlation coefficients, and ANCOVA. RESULTS Interrater reliability for BCS and MCS assessment was high (correlation coefficients, 0.95 and 0.83, respectively). No significant effect was identified for order of SAP measurement sites. Coccygeal and radial SAP were positively correlated (ρ = 0.45). The median difference in coccygeal versus radial SAP was 19 mm Hg, but differences were not consistently positive or negative. Radial SAP was positively correlated with age (ρ = 0.48) and negatively correlated with MCS (ρ = -0.30). On the basis of the correlation analysis, the association between radial SAP and MCS reflected the confounding influence of age. Coccygeal SAP was not significantly correlated with age, BCS, or MCS. CONCLUSIONS AND CLINICAL RELEVANCE Use of the coccygeal artery is recommended to reduce the confounding effects of age and sarcopenia on Doppler ultrasonographic SAP measurements in cats. Additionally, monitoring for changes in MCS is recommended for cats undergoing serial SAP measurement.

Impact of Antiretroviral Treatment Containing Tenofovir Difumarate on the Telomere Length of Aviremic HIV-Infected Patients.

PubMed

Montejano, Rocio; Stella-Ascariz, Natalia; Monge, Susana; Bernardino, José I; Pérez-Valero, Ignacio; Montes, María L; Valencia, Eulalia; Martín-Carbonero, Luz; Moreno, Victoria; González-García, Juan; Arnalich, Francisco; Mingorance, Jesús; Pintado Berniches, Laura; Perona, Rosario; Arribas, José R

2017-09-01

To evaluate the in vivo relevance of the inhibitory effect of tenofovir on telomerase activity observed in vitro. Cross-sectional study of HIV-infected patients with suppressed virological replication (HIV RNA <50 copies/mL for more than 1 year). Telomere length in whole blood was measured by quantitative real-time polymerase chain reaction. We performed a multivariate analysis to elucidate variables associated with telomere length and also evaluated the association between telomere length and use of tenofovir difumarate (TDF) adjusted by significant confounders. 200 patients included, 72% men, median age 49 (IQR 45-54.5), 103 with exposure to a TDF containing antiretroviral treatment (ART) regimen (69.9% for more than 5 years) and 97 never exposed to a TDF containing ART regimen. In the multivariate analysis, significant predictors of shorter telomere length were older age (P = 0.008), parental age at birth (P = 0.038), white race (P = 0.048), and longer time of known HIV infection (10-20 and ≥20 years compared with <10 years, P = 0.003 and P = 0.056, respectively). There was no association between TDF exposure and telomere length after adjusting for possible confounding factors (age, parental age at birth, race, and time of HIV infection). Total time receiving ART and duration of treatment with nucleoside reverse transcriptase inhibitors were associated with shorter telomere length, but these associations were explained by time of known HIV infection. Our data do not suggest that telomerase activity inhibition caused by TDF in vitro leads to telomere shortening in peripheral blood of HIV-infected patients.

Daily commuting to work is not associated with variables of health.

PubMed

Mauss, Daniel; Jarczok, Marc N; Fischer, Joachim E

2016-01-01

Commuting to work is thought to have a negative impact on employee health. We tested the association of work commute and different variables of health in German industrial employees. Self-rated variables of an industrial cohort (n = 3805; 78.9 % male) including absenteeism, presenteeism and indices reflecting stress and well-being were assessed by a questionnaire. Fasting blood samples, heart-rate variability and anthropometric data were collected. Commuting was grouped into one of four categories: 0-19.9, 20-44.9, 45-59.9, ≥60 min travelling one way to work. Bivariate associations between commuting and all variables under study were calculated. Linear regression models tested this association further, controlling for potential confounders. Commuting was positively correlated with waist circumference and inversely with triglycerides. These associations did not remain statistically significant in linear regression models controlling for age, gender, marital status, and shiftwork. No other association with variables of physical, psychological, or mental health and well-being could be found. The results indicate that commuting to work has no significant impact on well-being and health of German industrial employees.

Effects of Age at First Childbirth and Other Factors on Central Obesity in Postmenopausal Women: The 2013–2015 Korean National Health and Nutrition Examination Survey

PubMed Central

Lee, Wang Jin; Lee, Joo Ha; Kwag, Byoung Gyu; Chang, Shin Hae; Choi, Yu Jin

2018-01-01

Background Waist circumference is one of the key components of metabolic syndrome. Recent studies demonstrated that the reproductive profile was associated with metabolic syndrome in postmenopausal women. This study focused on the association between central obesity and age at first childbirth. It also considered other factors associated with central obesity in postmenopausal women. Methods This study was based on the 2013–2015 Korean National Health and Nutrition Examination Survey and involved 3,143 naturally postmenopausal women. These women were divided into three groups according to their age at first childbirth: 19 years or younger (n=252), 20–29 years (n=2,695), and 30 years or older (n=196). Multivariate analysis using logistic regression was performed to evaluate the effects of various reproductive factors, including other confounding factors. Results During adjustment for confounding factors, in the early age at first childbirth group, odds ratios (95% confidence intervals) for central obesity decreased. In the final model, younger age at first childbirth was not significantly related to central obesity (waist circumference more than 85 cm) in naturally postmenopausal women after adjusting for other confounding factors. Conclusion Younger age at first childbirth was not significantly associated with central obesity after adjustment for confounding factors. PMID:29788703

Three estimates of the association between linear growth failure and cognitive ability.

PubMed

Cheung, Y B; Lam, K F

2009-09-01

To compare three estimators of association between growth stunting as measured by height-for-age Z-score and cognitive ability in children, and to examine the extent statistical adjustment for covariates is useful for removing confounding due to socio-economic status. Three estimators, namely random-effects, within- and between-cluster estimators, for panel data were used to estimate the association in a survey of 1105 pairs of siblings who were assessed for anthropometry and cognition. Furthermore, a 'combined' model was formulated to simultaneously provide the within- and between-cluster estimates. Random-effects and between-cluster estimators showed strong association between linear growth and cognitive ability, even after adjustment for a range of socio-economic variables. In contrast, the within-cluster estimator showed a much more modest association: For every increase of one Z-score in linear growth, cognitive ability increased by about 0.08 standard deviation (P < 0.001). The combined model verified that the between-cluster estimate was significantly larger than the within-cluster estimate (P = 0.004). Residual confounding by socio-economic situations may explain a substantial proportion of the observed association between linear growth and cognition in studies that attempt to control the confounding by means of multivariable regression analysis. The within-cluster estimator provides more convincing and modest results about the strength of association.

An education gradient in health, a health gradient in education, or a confounded gradient in both?

PubMed

Lynch, Jamie L; von Hippel, Paul T

2016-04-01

There is a positive gradient associating educational attainment with health, yet the explanation for this gradient is not clear. Does higher education improve health (causation)? Do the healthy become highly educated (selection)? Or do good health and high educational attainment both result from advantages established early in the life course (confounding)? This study evaluates these competing explanations by tracking changes in educational attainment and Self-rated Health (SRH) from age 15 to age 31 in the National Longitudinal Study of Youth, 1997 cohort. Ordinal logistic regression confirms that high-SRH adolescents are more likely to become highly educated. This is partly because adolescent SRH is associated with early advantages including adolescents' academic performance, college plans, and family background (confounding); however, net of these confounders adolescent SRH still predicts adult educational attainment (selection). Fixed-effects longitudinal regression shows that educational attainment has little causal effect on SRH at age 31. Completion of a high school diploma or associate's degree has no effect on SRH, while completion of a bachelor's or graduate degree have effects that, though significant, are quite small (less than 0.1 points on a 5-point scale). While it is possible that educational attainment would have greater effect on health at older ages, at age 31 what we see is a health gradient in education, shaped primarily by selection and confounding rather than by a causal effect of education on health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Association between age at onset of psychosis and age at onset of cannabis use in non-affective psychosis.

PubMed

Galvez-Buccollini, Juan A; Proal, Ashley C; Tomaselli, Veronica; Trachtenberg, Melissa; Coconcea, Cristinel; Chun, Jinsoo; Manschreck, Theo; Fleming, Jerry; Delisi, Lynn E

2012-08-01

Several studies have associated cannabis use with the development of schizophrenia. However, it has been difficult to disentangle the effects of cannabis from that of other illicit drugs, as previous studies have not evaluated pure cannabis users. To test whether the onset of cannabis use had an effect on the initiation of psychosis, we examined the time relationship between onset of use and onset of psychosis, restricting our analysis to a cohort of individuals who only used cannabis and no other street drugs. Fifty-seven subjects with non-affective psychoses who used cannabis prior to developing a psychosis were interviewed using the Diagnostic Interview for Genetic Studies (DIGS). The Family Interview for Genetic Studies (FIGS) was also used to interview a family informant about psychiatric illness in the patient and the entire family. Multiple linear regression techniques were used to estimate the association between variables. After adjusting for potential confounding factors such as sex, age, lifetime diagnosis of alcohol abuse or dependence, and family history of schizophrenia, the age at onset of cannabis was significantly associated with age at onset of psychosis (β=0.4, 95% CI=0.1-0.7, p=0.004) and age at first hospitalization (β=0.4, 95% CI=0.1-0.8, p=0.008). The mean time between beginning to use cannabis and onset of psychosis was 7.0±4.3. Age at onset of alcohol use was not associated with age at onset of psychosis or age at first hospitalization. Age at onset of cannabis is directly associated with age at onset of psychosis and age at first hospitalization. These associations remain significant after adjusting for potential confounding factors and are consistent with the hypothesis that cannabis could cause or precipitate the onset of psychosis after a prolonged period of time. Published by Elsevier B.V.

A pilot study of low-moderate drinking water arsenic contamination and chronic diseases among reproductive age women in Timiş County, Romania.

PubMed

Butts, Celeste D; Bloom, Michael S; Neamtiu, Iulia A; Surdu, Simona; Pop, Cristian; Anastasiu, Doru; Fitzgerald, Edward F; Gurzau, Eugen S

2015-11-01

We conducted a pilot study of associations between drinking water contaminated by inorganic arsenic (iAs), mostly <10 μg/L, and self-reported chronic diseases in 297 pregnant women. Adjusted for confounding variables, we identified a positive association between iAs and heart disease (OR = 1.63, 95%CI 0.81-3.04, p = 0.094), which was stronger for women living at their current residence ≥ 10 years (OR = 2.47, 95%CI 0.87-10.43, p = 0.058). Confounder-adjusted associations were also suggested for iAs with kidney disease (OR = 1.32, 95%CI 0.77-2.21, p = 0.265) and with high blood pressure (OR = 1.36, 95%CI 0.68-2.39, p = 0.300). A post hoc power analysis indicated the need for a larger study with more statistical power. Copyright © 2015 Elsevier B.V. All rights reserved.

Supportive Family Environments Ameliorate the Link Between Racial Discrimination and Epigenetic Aging: A Replication Across Two Longitudinal Cohorts

PubMed Central

Brody, Gene H.; Miller, Gregory E.; Yu, Tianyi; Beach, Steven R. H.; Chen, Edith

2015-01-01

This study tested the hypothesis that supportive family environments during adolescence will buffer exposure to racial discrimination, reducing its impact on biological weathering and its manifestation in cellular aging. Indicators of racial discrimination, supportive family environments, and covariates were collected for 3 consecutive years across adolescence from 2 independent cohorts of African American youth from rural Georgia. DNA was extracted from peripheral blood mononuclear cells collected during young adulthood. Patterns of methylation were used to index epigenetic ages of these cells and the extent to which they differed from participants’ chronological ages. Among youth in supportive family environments, exposure to high levels of racial discrimination did not forecast epigenetic aging. Among youth in less supportive family environments, exposure to high levels of racial discrimination forecast faster epigenetic aging. The results did not change when confounder variables were included in the data analyses, and the results were replicated across cohorts. PMID:26917213

The Problem of Confounding in Studies of the Effect of Maternal Drug Use on Pregnancy Outcome

PubMed Central

Källén, Bengt

2012-01-01

In most epidemilogical studies, the problem of confounding adds to the uncertainty in conclusions drawn. This is also true for studies on the effect of maternal drug use on birth defect risks. This paper describes various types of such confounders and discusses methods to identify and adjust for them. Such confounders can be found in maternal characteristics like age, parity, smoking, use of alcohol, and body mass index, subfertility, and previous pregnancies including previous birth of a malformed child, socioeconomy, race/ethnicity, or country of birth. Confounding by concomitant maternal drug use may occur. A geographical or seasonal confounding can exist. In rare instances, infant sex and multiple birth can appear as confounders. The most difficult problem to solve is often confounding by indication. The problem of confounding is less important for congenital malformations than for many other pregnancy outcomes. PMID:22190949

Solar radiation increases suicide rate after adjusting for other climate factors in South Korea.

PubMed

Jee, Hee-Jung; Cho, Chul-Hyun; Lee, Yu Jin; Choi, Nari; An, Hyonggin; Lee, Heon-Jeong

2017-03-01

Previous studies have indicated that suicide rates have significant seasonal variations. There is seasonal discordance between temperature and solar radiation due to the monsoon season in South Korea. We investigated the seasonality of suicide and assessed its association with climate variables in South Korea. Suicide rates were obtained from the National Statistical Office of South Korea, and climatic data were obtained from the Korea Meteorological Administration for the period of 1992-2010. We conducted analyses using a generalized additive model (GAM). First, we explored the seasonality of suicide and climate variables such as mean temperature, daily temperature range, solar radiation, and relative humidity. Next, we identified confounding climate variables associated with suicide rate. To estimate the adjusted effect of solar radiation on the suicide rate, we investigated the confounding variables using a multivariable GAM. Suicide rate showed seasonality with a pattern similar to that of solar radiation. We found that the suicide rate increased 1.008 times when solar radiation increased by 1 MJ/m 2 after adjusting for other confounding climate factors (P < 0.001). Solar radiation has a significant linear relationship with suicide after adjusting for region, other climate variables, and time trends. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

How Confounder Strength Can Affect Allocation of Resources in Electronic Health Records.

PubMed

Lynch, Kristine E; Whitcomb, Brian W; DuVall, Scott L

2018-01-01

When electronic health record (EHR) data are used, multiple approaches may be available for measuring the same variable, introducing potentially confounding factors. While additional information may be gleaned and residual confounding reduced through resource-intensive assessment methods such as natural language processing (NLP), whether the added benefits offset the added cost of the additional resources is not straightforward. We evaluated the implications of misclassification of a confounder when using EHRs. Using a combination of simulations and real data surrounding hospital readmission, we considered smoking as a potential confounder. We compared ICD-9 diagnostic code assignment, which is an easily available measure but has the possibility of substantial misclassification of smoking status, with NLP, a method of determining smoking status that more expensive and time-consuming than ICD-9 code assignment but has less potential for misclassification. Classification of smoking status with NLP consistently produced less residual confounding than the use of ICD-9 codes; however, when minimal confounding was present, differences between the approaches were small. When considerable confounding is present, investing in a superior measurement tool becomes advantageous.

The enduring effect of education-socioeconomic differences in disability trajectories from age 85 years in the Newcastle 85+ Study.

PubMed

Kingston, Andrew; Davies, Karen; Collerton, Joanna; Robinson, Louise; Duncan, Rachel; Kirkwood, Thomas B L; Jagger, Carol

2015-01-01

Little is known about disability progression in very old age despite this being vital for care planning. We investigate whether distinct trajectories of disability are evident from age 85 to 90 and their association with socio-economic status (SES). The Newcastle 85+ Study recruited people born in 1921 through participating general practices in Newcastle and North Tyneside. Participants underwent a health assessment (HA) at baseline, 18, 36 and 60 months and a GP record review (GPRR) at baseline, 36 and 60 months. Disability was measured via difficulty in 17 Activities of Daily Living. Trajectory identification was assessed by gender stratified, mortality adjusted, group-based trajectory modelling (GBTM) and the impact of life-course SES (level of education; occupational class; deprivation) on trajectory membership evaluated (adjusting for confounding variables). 851 participants agreed to HA and GPRR, 840 (98.7%) with complete disability data. Four distinct trajectories were evident for both sexes. A disability-free trajectory between age 85 and 90 was identified in men only (9% of the sample). The most disabled trajectories had severe disability at age 85 progressing to profound disability by age 90. After adjusting for confounders education remained significant; men and women with most education being less likely to be in the most disabled trajectory (Men: OR=0.80, 95% CI 0.65-0.98; women: OR=0.59, 95% CI 0.42-0.83). Distinct disability trajectories are evident in the very old and these are influenced by education, suggesting SES disadvantages cumulate throughout the life-course to create health and mortality inequalities later. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Mismeasurement and the resonance of strong confounders: correlated errors.

PubMed

Marshall, J R; Hastrup, J L; Ross, J S

1999-07-01

Confounding in epidemiology, and the limits of standard methods of control for an imperfectly measured confounder, have been understood for some time. However, most treatments of this problem are based on the assumption that errors of measurement in confounding and confounded variables are independent. This paper considers the situation in which a strong risk factor (confounder) and an inconsequential but suspected risk factor (confounded) are each measured with errors that are correlated; the situation appears especially likely to occur in the field of nutritional epidemiology. Error correlation appears to add little to measurement error as a source of bias in estimating the impact of a strong risk factor: it can add to, diminish, or reverse the bias induced by measurement error in estimating the impact of the inconsequential risk factor. Correlation of measurement errors can add to the difficulty involved in evaluating structures in which confounding and measurement error are present. In its presence, observed correlations among risk factors can be greater than, less than, or even opposite to the true correlations. Interpretation of multivariate epidemiologic structures in which confounding is likely requires evaluation of measurement error structures, including correlations among measurement errors.

Cancer biomarker discovery is improved by accounting for variability in general levels of drug sensitivity in pre-clinical models.

PubMed

Geeleher, Paul; Cox, Nancy J; Huang, R Stephanie

2016-09-21

We show that variability in general levels of drug sensitivity in pre-clinical cancer models confounds biomarker discovery. However, using a very large panel of cell lines, each treated with many drugs, we could estimate a general level of sensitivity to all drugs in each cell line. By conditioning on this variable, biomarkers were identified that were more likely to be effective in clinical trials than those identified using a conventional uncorrected approach. We find that differences in general levels of drug sensitivity are driven by biologically relevant processes. We developed a gene expression based method that can be used to correct for this confounder in future studies.

Term-equivalent functional brain maturational measures predict neurodevelopmental outcomes in premature infants.

PubMed

El Ters, Nathalie M; Vesoulis, Zachary A; Liao, Steve M; Smyser, Christopher D; Mathur, Amit M

2018-04-01

Term equivalent age (TEA) brain MRI identifies preterm infants at risk for adverse neurodevelopmental outcomes. But some infants may experience neurodevelopmental impairments even in the absence of neuroimaging abnormalities. Evaluate the association of TEA amplitude-integrated EEG (aEEG) measures with neurodevelopmental outcomes at 24-36 months corrected age. We performed aEEG recordings and brain MRI at TEA (mean post-menstrual age of 39 (±2) weeks in a cohort of 60 preterm infants born at a mean gestational age of 26 (±2) weeks. Forty-four infants underwent Bayley Scales of Infant Development, 3rd Edition (BSID-III) testing at 24-36 months corrected age. Developmental delay was defined by a score greater than one standard deviation below the mean (<85) in any domain. An ROC curve was constructed and a value of SEF 90  < 9.2, yielded the highest sensitivity and specificity for moderate/severe brain injury on MRI. The association between aEEG measures and neurodevelopmental outcomes was assessed using odds ratio, then adjusted for confounding variables using logistic regression. Infants with developmental delay in any domain had significantly lower values of SEF 90 . Absent cyclicity was more prevalent in infants with cognitive and motor delay. Both left and right SEF 90  < 9.2 were associated with motor delay (OR left: 4.7(1.2-18.3), p = 0.02, OR right: 7.9 (1.8-34.5), p < 0.01). Left SEF 90 and right SEF 90 were associated with cognitive delay and language delay respectively. Absent cyclicity was associated with motor and cognitive delay (OR for motor delay: 5.8 (1.3-25.1), p = 0.01; OR for cognitive delay: 16.8 (3.1-91.8), p < 0.01). These associations remained significant after correcting for social risk index score and confounding variables. aEEG may be used at TEA as a new tool for risk stratification of infants at higher risk of poor neurodevelopmental outcomes. Therefore, a larger study is needed to validate these results in premature infants at low and high risk of brain injury. Copyright © 2018. Published by Elsevier B.V.

Use of instrumental variables in the analysis of generalized linear models in the presence of unmeasured confounding with applications to epidemiological research.

PubMed

Johnston, K M; Gustafson, P; Levy, A R; Grootendorst, P

2008-04-30

A major, often unstated, concern of researchers carrying out epidemiological studies of medical therapy is the potential impact on validity if estimates of treatment are biased due to unmeasured confounders. One technique for obtaining consistent estimates of treatment effects in the presence of unmeasured confounders is instrumental variables analysis (IVA). This technique has been well developed in the econometrics literature and is being increasingly used in epidemiological studies. However, the approach to IVA that is most commonly used in such studies is based on linear models, while many epidemiological applications make use of non-linear models, specifically generalized linear models (GLMs) such as logistic or Poisson regression. Here we present a simple method for applying IVA within the class of GLMs using the generalized method of moments approach. We explore some of the theoretical properties of the method and illustrate its use within both a simulation example and an epidemiological study where unmeasured confounding is suspected to be present. We estimate the effects of beta-blocker therapy on one-year all-cause mortality after an incident hospitalization for heart failure, in the absence of data describing disease severity, which is believed to be a confounder. 2008 John Wiley & Sons, Ltd

Negative psychological aspects and survival in lung cancer patients.

PubMed

Nakaya, Naoki; Saito-Nakaya, Kumi; Akechi, Tatsuo; Kuriyama, Shinichi; Inagaki, Masatoshi; Kikuchi, Nobutaka; Nagai, Kanji; Tsugane, Shoichiro; Nishiwaki, Yutaka; Tsuji, Ichiro; Uchitomi, Yosuke

2008-05-01

We conducted a prospective cohort study in Japan to investigate associations between negative psychological aspects and cancer survival. Between July 1999 and July 2004, a total of 1178 lung cancer patients were enrolled. The questionnaire asked about socioeconomic variables, smoking status, clinical symptoms, and psychological aspects after diagnosis. Negative psychological aspects were assessed for the subscales of helplessness/hopelessness and depression. Clinical stage, performance status (PS), and histologic type were obtained from medical charts. The subjects were followed up until December 2004, and 686 had died. A Cox regression model was used to estimate the hazards ratio (HR) of all-cause mortality. After adjustment for socioeconomic variables and smoking status in addition to sex, age, and histologic type, both helplessness/hopelessness and depression subscales showed significant linear positive associations with the risk of mortality (p for trend<0.001 for both). However, after adjustment for clinical state variables in addition to sex, age, and histologic type, these significant linear positive associations were no longer observed (p for trend=0.41 and 0.26, respectively). Our data supported the hypothesis that the association between helplessness/hopelessness and depression and the risk of mortality among lung cancer patients was largely confounded by clinical state variables including clinical stage, PS, and clinical symptoms. (c) 2007 John Wiley & Sons, Ltd.

The effect of socio-demographic variables and dairy use on the intake of essential macro- and micronutrients in 0.5-12-year-old Indonesian children.

PubMed

Widodo, Yekti; Sandjaja, Sandjaja; Sumedi, Edith; Khouw, Ilse; Deurenberg, Paul

2016-01-01

To study the associations between nutrient intake, dairy intake and socioeconomic variables. Food consumption data using 24 h recall were collected in 3600 children, aged 0.5 to 12 years old in addition to frequency of dairy use and anthropometric and sociodemographic variables. Overall height for age Z-score (HAZ) and body mass index for age Z-score (BAZ) values (mean±SE) were -1.40±0.03 and -0.48±0.03 respectively, associated with a high prevalence of stunting and thinness in the population. The overall percentage of children not using any dairy products was 71%, and this percentage increased steadily with age. The overall energy intake from dairy was 99±3 kcal/capita/day and the overall energy intake from dairy in dairy users was 291±7 kcal/day. Dairy use did not differ between boys and girls, but was higher in urban areas, higher if the education of the mother was higher and higher if the mother had a permanent job and if the wealth status of the family was in the upper levels. Nutrient intake after the age of 3 years was inadequate for energy and all nutrients except for protein. The achievement of Recommended Dietary Allowances (RDA) for all nutrients was higher in dairy users compared to non-dairy users, also after correcting for the confounding effect of the higher energy intake (from dairy) and socio-demographic variables. The contribution increased with increasing frequency of dairy use. Adequate dairy intake can substantially add to the achievement of RDA in Indonesian children.

Nutritional Risk is Associated with Chronic Musculoskeletal Pain in Community-dwelling Older Persons: The PAINEL Study.

PubMed

Bárbara Pereira Costa, Aline; Andrade Carneiro Machado, Luciana; Marcos Domingues Dias, João; Keller Coelho de Oliveira, Adriana; Ude Viana, Joana; da Silva, Sílvia Lanziotti Azevedo; Gonçalves Pereira Couto, Flávia; Lustosa Torres, Juliana; Mendes, Liliane P; Correa Dias, Rosangela

2016-01-01

Malnutrition is a risk factor for noncommunicable diseases related to ageing, and it can also contribute to musculoskeletal health. This study investigated whether nutritional risk is associated with chronic musculoskeletal pain in community-dwelling older persons. Nutritional risk was assessed by the DETERMINE Checklist. Chronic musculoskeletal pain was defined as the presence of pain in the past six months that did not disappear for at least 30 consecutive days. Multivariate logistic regression including confounding variables was used for the analysis. The sample was comprised of 383 participants (age 75.6 ± SD 6.1); the majority were at moderate-to-high nutritional risk (69%) and approximately one third presented chronic musculoskeletal pain (30%). The nutritional risk score was independently associated with chronic musculoskeletal pain: adding one unit in the risk score produces an 11% increment in the odds of presenting pain (OR 1.109, 95% CI 1.022-1.204). Individuals classified into moderate- or high-risk categories also had substantially higher odds (∼90%) of presenting chronic musculoskeletal pain when compared to those in the low-risk category, although our findings were only marginally significant. This is the first study to demonstrate the association between nutritional risk and chronic musculoskeletal pain above and beyond the contributed effects from relevant confounders.

Relation of Heart Rate and its Variability during Sleep with Age, Physical Activity, and Body Composition in Young Children

PubMed Central

Herzig, David; Eser, Prisca; Radtke, Thomas; Wenger, Alina; Rusterholz, Thomas; Wilhelm, Matthias; Achermann, Peter; Arhab, Amar; Jenni, Oskar G.; Kakebeeke, Tanja H.; Leeger-Aschmann, Claudia S.; Messerli-Bürgy, Nadine; Meyer, Andrea H.; Munsch, Simone; Puder, Jardena J.; Schmutz, Einat A.; Stülb, Kerstin; Zysset, Annina E.; Kriemler, Susi

2017-01-01

Background: Recent studies have claimed a positive effect of physical activity and body composition on vagal tone. In pediatric populations, there is a pronounced decrease in heart rate with age. While this decrease is often interpreted as an age-related increase in vagal tone, there is some evidence that it may be related to a decrease in intrinsic heart rate. This factor has not been taken into account in most previous studies. The aim of the present study was to assess the association between physical activity and/or body composition and heart rate variability (HRV) independently of the decline in heart rate in young children. Methods: Anthropometric measurements were taken in 309 children aged 2–6 years. Ambulatory electrocardiograms were collected over 14–18 h comprising a full night and accelerometry over 7 days. HRV was determined of three different night segments: (1) over 5 min during deep sleep identified automatically based on HRV characteristics; (2) during a 20 min segment starting 15 min after sleep onset; (3) over a 4-h segment between midnight and 4 a.m. Linear models were computed for HRV parameters with anthropometric and physical activity variables adjusted for heart rate and other confounding variables (e.g., age for physical activity models). Results: We found a decline in heart rate with increasing physical activity and decreasing skinfold thickness. HRV parameters decreased with increasing age, height, and weight in HR-adjusted regression models. These relationships were only found in segments of deep sleep detected automatically based on HRV or manually 15 min after sleep onset, but not in the 4-h segment with random sleep phases. Conclusions: Contrary to most previous studies, we found no increase of standard HRV parameters with age, however, when adjusted for heart rate, there was a significant decrease of HRV parameters with increasing age. Without knowing intrinsic heart rate correct interpretation of HRV in growing children is impossible. PMID:28286485

Relation of Heart Rate and its Variability during Sleep with Age, Physical Activity, and Body Composition in Young Children.

PubMed

Herzig, David; Eser, Prisca; Radtke, Thomas; Wenger, Alina; Rusterholz, Thomas; Wilhelm, Matthias; Achermann, Peter; Arhab, Amar; Jenni, Oskar G; Kakebeeke, Tanja H; Leeger-Aschmann, Claudia S; Messerli-Bürgy, Nadine; Meyer, Andrea H; Munsch, Simone; Puder, Jardena J; Schmutz, Einat A; Stülb, Kerstin; Zysset, Annina E; Kriemler, Susi

2017-01-01

Background: Recent studies have claimed a positive effect of physical activity and body composition on vagal tone. In pediatric populations, there is a pronounced decrease in heart rate with age. While this decrease is often interpreted as an age-related increase in vagal tone, there is some evidence that it may be related to a decrease in intrinsic heart rate. This factor has not been taken into account in most previous studies. The aim of the present study was to assess the association between physical activity and/or body composition and heart rate variability (HRV) independently of the decline in heart rate in young children. Methods: Anthropometric measurements were taken in 309 children aged 2-6 years. Ambulatory electrocardiograms were collected over 14-18 h comprising a full night and accelerometry over 7 days. HRV was determined of three different night segments: (1) over 5 min during deep sleep identified automatically based on HRV characteristics; (2) during a 20 min segment starting 15 min after sleep onset; (3) over a 4-h segment between midnight and 4 a.m. Linear models were computed for HRV parameters with anthropometric and physical activity variables adjusted for heart rate and other confounding variables (e.g., age for physical activity models). Results: We found a decline in heart rate with increasing physical activity and decreasing skinfold thickness. HRV parameters decreased with increasing age, height, and weight in HR-adjusted regression models. These relationships were only found in segments of deep sleep detected automatically based on HRV or manually 15 min after sleep onset, but not in the 4-h segment with random sleep phases. Conclusions: Contrary to most previous studies, we found no increase of standard HRV parameters with age, however, when adjusted for heart rate, there was a significant decrease of HRV parameters with increasing age. Without knowing intrinsic heart rate correct interpretation of HRV in growing children is impossible.

The NASA-Sponsored Study of Cataract in Astronauts (NASCA). Relationship of Exposure to Radiation in Space and the Risk of Cataract Incidence and Progression. Report 1: Recruitment and Methodology

NASA Technical Reports Server (NTRS)

Chylack, Leo T.; Peterson, Leif E.; Feiveson, Alan H.; Wear, Mary; Manuel, F. Keith

2007-01-01

The NASA Study of Cataract in Astronauts (NASCA) is a five-year, multi-centered, investigation of lens opacification in populations of U.S. astronauts, military pilots, and ground-based (nonaviator) comparison participants. For astronauts, the explanatory variable of most interest is radiation exposure during space flight, however to properly evaluate its effect, the secondary effects of age, nutrition, general health, solar ocular exposure, and other confounding variables encountered in non-space flight must also be considered. NASCA contains an initial baseline, cross-sectional objective assessment of the severity of cortical (C), nuclear (N), and posterior subcapsular (PSC) lens opacification, and annual follow-on assessments of severity and progression of these opacities in the population of astronauts and in participants sampled from populations of military pilots and ground-based exposure controls. From these data, NASCA will estimate the degree to which space radiation affects lens opacification for astronauts and how the overall risks of each cataract type for astronauts compared with those of the other exposure control groups after adjusting for differences in age and other explanatory variables.

Dietary supplement use and smoking are important correlates of biomarkers of water-soluble vitamin status after adjusting for sociodemographic and lifestyle variables in a representative sample of US adults1,2,3

PubMed Central

Pfeiffer, Christine M.; Sternberg, Maya R.; Schleicher, Rosemary L.; Rybak, Michael E.

2016-01-01

Biochemical indicators of water-soluble vitamin (WSV) status have been measured in a nationally representative sample of the US population in NHANES 2003–2006. To examine whether demographic differentials in nutritional status were related to and confounded by certain variables, we assessed the association of sociodemographic (age, sex, race-ethnicity, education, income) and lifestyle variables (dietary supplement use, smoking, alcohol consumption, BMI, physical activity) with biomarkers of WSV status in adults (≥20 y): serum and RBC folate, serum pyridoxal-5′-phosphate (PLP), serum 4-pyridoxic acid, serum total cobalamin (B-12), plasma total homocysteine (tHcy), plasma methylmalonic acid (MMA), and serum ascorbic acid. Age (except for PLP) and smoking (except for MMA) were generally the strongest significant correlates of these biomarkers (|r| ≤0.43) and together with supplement use explained more of the variability as compared to the other covariates in bivariate analysis. In multiple regression models, sociodemographic and lifestyle variables together explained from 7% (B-12) to 29% (tHcy) of the biomarker variability. We observed significant associations for most biomarkers (≥6 out of 8) with age, sex, race-ethnicity, supplement use, smoking, and BMI; and for some biomarkers with PIR (5/8), education (1/8), alcohol consumption (4/8), and physical activity (5/8). We noted large estimated percent changes in biomarker concentrations between race-ethnic groups (from −24% to 20%), between supplement users and nonusers (from −12% to 104%), and between smokers and nonsmokers (from −28% to 8%). In summary, age, sex, and race-ethnic differentials in biomarker concentrations remained significant after adjusting for sociodemographic and lifestyle variables. Supplement use and smoking were important correlates of biomarkers of WSV status. PMID:23576641

Videofluoroscopic and Manometric Evaluation of Pharyngeal and Upper Esophageal Sphincter Function During Swallowing

PubMed Central

Yoon, Kyung Jae; Park, Jung Ho; Park, Jung Hwan; Jung, Il Seok

2014-01-01

Background/Aims The purpose of this study was to determine important manometric metrics for the analysis of pharyngeal and upper esophageal sphincter (UES) function and to investigate the effect of viscosity and other confounding factors on manometric results. Methods Manometric studies were performed on 26 asymptomatic volunteers (12 men and 14 women; age, 19–81 years). The manometric protocol included 5 water swallows (5 mL), 5 barium swallows (5 mL) and 5 yogurt swallows (5 mL). Evaluation of high-resolution manometry parameters including basal pressure of the UES, mesopharyngeal contractile integral (mesopharyngeal CI, mmHg · cm · sec), CI of the hypopharynx and UES (hypopharyngeal CI), relaxation interval of UES, median intrabolus pressure and nadir pressure at UES was performed using MATLAB. Results Mesopharyngeal CIs for barium and yogurt swallows were significantly lower than those for water swallows (both P < 0.05). Hypopharyngeal CIs for water swallows were significantly lower than those for barium swallows (P = 0.004), and median bolus pressure at UES for barium swallows was significantly higher than that for water and yogurt swallows (both P < 0.05). Furthermore, hypopharyngeal CI and median intrabolus pressure at UES were significantly related to age for 3 swallows (all P < 0.01 and P < 0.05, respectively). A significant negative correlation was also noted between nadir pressure at UES and age for water and yogurt swallows (all P < 0.05). Conclusions Manometric measurement of the pharynx and UES varies with respect to viscosity. Moreover, age could be a confounding variable in the interpretation of pharyngeal manometry. PMID:24847841

Are attractive men's faces masculine or feminine? The importance of controlling confounds in face stimuli.

PubMed

DeBruine, Lisa M; Jones, Benedict C; Smith, Finlay G; Little, Anthony C

2010-06-01

Women's preferences for male masculinity are highly variable. Although many researchers explain this variability as reflecting systematic individual differences in how women resolve the tradeoff between the costs and benefits of choosing a masculine partner, others suggest that methodological differences between studies are responsible. A recent study found general femininity preferences for judgments of faces that were manipulated in sexual dimorphism of shape but general masculinity preferences for judgments of faces that were based on perceived masculinity. Using the original stimuli, we replicated these previous results but found equivalent general femininity preferences for both types of faces when nonface confounds in the stimuli (e.g. hairstyle) were eliminated through masking. We conclude that care must be taken to control potential confounds in stimuli and that the influence of nonface cues on preferences for facial masculinity deserves further study.

The associations between family characteristics and depressive symptoms in older adults: a community-based survey in rural China.

PubMed

Gong, Yanhong; Wen, Xiaopiao; Guan, Chaoping; Wang, Zhiqing; Liang, Yuan

2012-08-01

The aim of the current study was to investigate the associations between family characteristics and depressive symptoms, and provide new evidence and recommendations for prevention and intervention in the depressive symptoms of older adults. The study was a cross-sectional survey conducted door-to-door, utilizing a sample of 1,317 individuals aged 60 years and above in rural China. The five family characteristic variables recorded were: living with spouse, living with descendant, support of family members, self-reported family economic status in the previous year, and family-related negative life events that occurred anytime in the past with a continuous psychological effect during the past 12 months. Gender, age, years of schooling, and self-rated physical health status were taken as potential confounders. Univariable and multivariable logistic regression models were used to examine independent effects on depressive symptoms. In addition to the potential confounders, only family-related negative life events, support of family members, and self-reported family economic status had significant effects on depressive symptoms in older adults. Experiencing a family-related negative life event was the most significant variable (OR = 11.70, 95% CI: 7.72-17.73), the second was support of family members (OR = 6.93, 95% CI: 3.26-14.70), while family economic status was less important than support of family members (OR = 2.38, 95% CI: 1.08-5.25). This study, from the perspective of family characteristics on depressive symptoms in older adults, showed a strong correlation between being exposed to harmful family environments and depressive symptoms among the elderly. Efforts to address family risk factors and strengthen family cohesiveness deserve a higher priority, given the importance of these factors, compared with other efforts such as promoting economic development.

Is breastfeeding in infancy predictive of child mental well-being and protective against obesity at 9 years of age?

PubMed

Reynolds, D; Hennessy, E; Polek, E

2014-11-01

Preventing child mental health problems and child obesity have been recognized as public health priorities. The aim of the present study was to examine whether being breastfed (at all or exclusively) in infancy was a predictor of mental well-being and protective against risk of obesity at age 9. Cross-sectional data from a large, nationally representative cohort study in the Republic of Ireland was used (n = 8357). Data on breastfeeding were retrospectively recalled. Child mental well-being was assessed using a parent-completed Strengths and Difficulties Questionnaire (SDQ). Child's height and weight were measured using scientifically calibrated instruments. Logistic regression analyses indicated that, after controlling for a wide range of potential confounding variables, being breastfed in infancy was associated with a 26% (P < 0.05) reduction in the risk of an abnormal SDQ score at 9 years. Being breastfed remained a significant predictor of child mental well-being when child obesity was controlled for, indicating that being breastfed, independent of child obesity, is a predictor of child mental well-being. The results of a second logistic regression indicated that, after controlling for a wide range of potential confounding variables, being breastfed for between 11 and 25 weeks was associated with a 36% (P < 0.05) reduction in the risk of obesity at 9 years, while being breastfed for 26 weeks or longer was associated with a 48% (P < 0.01) reduction in the risk of obesity at 9 years. Breastfeeding in infancy may protect against both poor mental well-being and obesity in childhood. © 2013 John Wiley & Sons Ltd.

Echocardiographic nomograms for chamber diameters and areas in Caucasian children.

PubMed

Cantinotti, Massimiliano; Scalese, Marco; Murzi, Bruno; Assanta, Nadia; Spadoni, Isabella; De Lucia, Vittoria; Crocetti, Maura; Cresti, Alberto; Gallotta, Milena; Marotta, Marco; Tyack, Karin; Molinaro, Sabrina; Iervasi, Giorgio

2014-12-01

Although a quantitative evaluation of cardiac chamber dimensions in pediatric echocardiography is often important, nomograms for these structures are limited. The aim of this study was to establish reliable echocardiographic nomograms of cardiac chamber diameters and areas in a wide population of children. A total of 1,091 Caucasian Italian healthy children (age range, 0 days to 17 years; 44.8% female) with body surface areas (BSAs) ranging from 0.12 to 1.8 m(2) were prospectively enrolled. Twenty-two two-dimensional and M-mode measurements of atrial and ventricular chamber diameters and areas were performed. Models using linear, logarithmic, exponential, and square-root relationships were tested. Heteroscedasticity was tested by the White test and the Breusch-Pagan test. Age, weight, height, and BSA, calculated by the Haycock formula, were used as the independent variables in different analyses to predict the mean value of each echocardiographic measurement. The influence of various confounders, including gender, type of delivery, prematurity, and interobserver variability, was also evaluated. Structured Z scores were then computed. The Haycock formula provided the best fit and was used when presenting data as predicted values (mean ± 2 SDs) for a given BSA and within equations relating echocardiographic measurements to BSA. Confounders were not included in the final models, because they did not show significant effects for most of the measurements. Echocardiographic reference values are presented for chamber area and diameters, derived from a large population of healthy children. These data partly cover a gap in actual pediatric echocardiographic nomograms. Further studies are required to reinforce these data, as well as to evaluate other parameters and ethnicities. Copyright © 2014 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Maternal asthma and transient tachypnea of the newborn.

PubMed

Demissie, K; Marcella, S W; Breckenridge, M B; Rhoads, G G

1998-07-01

To examine the relationship between transient tachypnea of the newborn and asthma complicating pregnancy. Historical cohort analysis. Setting. Singleton live deliveries in New Jersey hospitals during 1989 to 1992 (n = 447 963). Mother-infant dyads were identified from linked birth certificate and maternal and infant hospital claims data. Women with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code (493) for asthma (n = 2289) were compared with a four-fold larger randomly selected control sample (n = 9156) from the remaining pool of women. Transient tachypnea of the newborn. In the overall sample, after controlling for the confounding effects of important variables, infants of asthmatic mothers were more likely [odds ratio (OR), 1. 79; 95% confidence interval (CI), 1.35-2.37] than infants of control mothers to exhibit transient tachypnea of the newborn. A stratified analysis by gestational age and sex revealed larger and statistically significant associations in term infants (OR, 2.02; 95% CI, 1.42-2.87) as opposed to preterm infants (OR, 1.51; 95% CI, 0.94-2.43) and in male infants (OR, 1.91; 95% CI, 1.35-2.71) as opposed to female infants (OR, 1.51; 95% CI, 0.92-2.47). On the other hand, after adjusting for important confounding variables, respiratory distress syndrome and maternal asthma were not found to be associated (OR, 1.14; 95% CI, 0.79-1.64). The results of this study provide evidence that maternal asthma is a risk factor for transient tachypnea of the newborn and differences in gestational age and sex were apparent in this association. The mechanism for this association remains to be determined.

Associations Between Sleep Duration Patterns and Behavioral/Cognitive Functioning at School Entry

PubMed Central

Touchette, Évelyne; Petit, Dominique; Séguin, Jean R.; Boivin, Michel; Tremblay, Richard E.; Montplaisir, Jacques Y.

2007-01-01

Objective: The aim of the study was to investigate the associations between longitudinal sleep duration patterns and behavioral/cognitive functioning at school entry. Design, Setting, and Participants: Hyperactivity-impulsivity (HI), inattention, and daytime sleepiness scores were measured by questionnaire at 6 years of age in a sample of births from 1997 to 1998 in a Canadian province (N=1492). The Peabody Picture Vocabulary Test - Revised (PPVT-R) was administered at 5 years of age and the Block Design subtest (WISC-III) was administered at 6 years of age. Sleep duration was reported yearly by the children's mothers from age 2.5 to 6 years. A group-based semiparametric mixture model was used to estimate developmental patterns of sleep duration. The relationships between sleep duration patterns and both behavioral items and neurodevelopmental tasks were tested using weighted multivariate logistic regression models to control for potentially confounding psychosocial factors. Results: Four sleep duration patterns were identified: short persistent (6.0%), short increasing (4.8%),10-hour persistent (50.3%), and 11-hour persistent (38.9%). The association of short sleep duration patterns with high HI scores (P=0.001), low PPVT-R performance (P=0.002), and low Block Design subtest performance (P=0.004) remained significant after adjusting for potentially confounding variables. Conclusions: Shortened sleep duration, especially before the age of 41 months, is associated with externalizing problems such as HI and lower cognitive performance on neurodevelopmental tests. Results highlight the importance of giving a child the opportunity to sleep at least 10 hours per night throughout early childhood. Citation: Touchette E; Petit D; Séguin JR; Boivin M; Tremblay RE; Montplaisir JY. Associations between sleep duration patterns and behavioral/cognitive functioning at school entry. SLEEP 2007;30(9):1213-1219. PMID:17910393

[The intelligence quotient and malnutrition. Iron deficiency and the lead concentration as confusing variables].

PubMed

Vega-Franco, L; Mejía, A M; Robles, B; Moreno, L; Pérez, Y

1991-11-01

This study gave us the opportunity to know the roles iron deficiency and the presence of lead in blood play, as confounding variables, in relation to the state of malnutrition and the intellect of those children. A sample of 169 school children were classified according to their state of nutrition, their condition in reference to serum iron and lead concentrations. In addition, their intelligence was evaluated. The results confirmed that those children with lower weights and heights registered lesser points of intelligence; in fact, iron deficiency cancels out the difference in favor of those taller and weighing more. Lead did not contribute as a confounding variable, but more than half of the children showed possible toxic levels of this metal.

The effects of own fetal growth on reported hypertension in parous women aged 33.

PubMed

Hennessy, E; Alberman, E

1997-06-01

Data from the study of the British 1958 birth cohort, National Child Development Study (NCDS), has allowed wider investigation of the relationship between retarded fetal growth and risk of adult hypertension. A history of self-reported hypertension was related to fetal growth in 3308 parous cohort members. Fetal growth, the measure used, is the difference in actual birthweight from that expected for the gestational age and subsequent adult height. The relationships were investigated both linearly and non-linearly adjusting for potential confounders. After adjustment for confounding factors, including adult weight for height, retarded fetal growth was associated with reported hypertension particularly when not confined to pregnancy. The latter was also associated with accelerated fetal growth, moderate or severe hypertension in the mother when pregnant with the cohort member, being relatively taller than your mother, and lack of educational qualifications. Hypertension confined to pregnancy was more likely among women who were themselves firstborn or older at childbirth. Neither maternal smoking during cohort's gestation nor cohort member's gestational age had a significant effect. The results are consistent with previous reports that fetal growth effects are less marked if gestation is short. The relationships between fetal growth and subsequent hypertension are extremely complex and variable, and need to be studied allowing for deviations from growth potential. Adult weight for height remains the strongest predictor of hypertension. The results suggest that losing weight is likely to have the same proportional benefit in women with and without a history of retarded fetal growth.

Depressive Symptoms and Salivary Telomere Length in a Probability Sample of Middle-Aged and Older Adults.

PubMed

Whisman, Mark A; Richardson, Emily D

To examine the association between depressive symptoms and salivary telomere length in a probability sample of middle-aged and older adults, and to evaluate age and sex as potential moderators of this association and test whether this association was incremental to potential confounds. Participants were 3,609 individuals from the 2008 wave of the Health and Retirement Study. Telomere length assays were performed using quantitative real-time polymerase chain reaction on DNA extracted from saliva samples. Depressive symptoms were assessed via interview, and health and lifestyle factors, traumatic life events, and neuroticism were assessed via self-report. Regression analyses were conducted to examine the associations between predictor variables and salivary telomere length. After adjusting for demographics, depressive symptoms were negatively associated with salivary telomere length (b = -.003; p = .014). Furthermore, this association was moderated by sex (b = .005; p = .011), such that depressive symptoms were significantly and negatively associated with salivary telomere length for men (b = - .006; p < .001) but not for women (b = - .001; p = .644). The negative association between depressive symptoms and salivary telomere length in men remained statistically significant after additionally adjusting for cigarette smoking, body mass index, chronic health conditions, childhood and lifetime exposure to traumatic life events, and neuroticism. Higher levels of depressive symptoms were associated with shorter salivary telomeres in men, and this association was incremental to several potential confounds. Shortened telomeres may help account for the association between depression and poor physical health and mortality.

Sleep patterns, sleep disorders and mammographic density in spanish women: The DDM-Spain/Var-DDM study.

PubMed

Pedraza-Flechas, Ana María; Lope, Virginia; Moreo, Pilar; Ascunce, Nieves; Miranda-García, Josefa; Vidal, Carmen; Sánchez-Contador, Carmen; Santamariña, Carmen; Pedraz-Pingarrón, Carmen; Llobet, Rafael; Aragonés, Nuria; Salas-Trejo, Dolores; Pollán, Marina; Pérez-Gómez, Beatriz

2017-05-01

We explored the relationship between sleep patterns and sleep disorders and mammographic density (MD), a marker of breast cancer risk. Participants in the DDM-Spain/var-DDM study, which included 2878 middle-aged Spanish women, were interviewed via telephone and asked questions on sleep characteristics. Two radiologists assessed MD in their left craneo-caudal mammogram, assisted by a validated semiautomatic-computer tool (DM-scan). We used log-transformed percentage MD as the dependent variable and fitted mixed linear regression models, including known confounding variables. Our results showed that neither sleeping patterns nor sleep disorders were associated with MD. However, women with frequent changes in their bedtime due to anxiety or depression had higher MD (e β :1.53;95%CI:1.04-2.26). Copyright © 2017 Elsevier B.V. All rights reserved.

Confounding by dietary patterns of the inverse association between alcohol consumption and type 2 diabetes risk.

PubMed

Imamura, Fumiaki; Lichtenstein, Alice H; Dallal, Gerard E; Meigs, James B; Jacques, Paul F

2009-07-01

The ability to interpret epidemiologic observations is limited because of potential residual confounding by correlated dietary components. Dietary pattern analyses by factor analysis or partial least squares may overcome the limitation. To examine confounding by dietary pattern as well as standard risk factors and selected nutrients, the authors modeled the longitudinal association between alcohol consumption and 7-year risk of type 2 diabetes mellitus in 2,879 healthy adults enrolled in the Framingham Offspring Study (1991-2001) by Cox proportional hazard models. After adjustment for standard risk factors, consumers of > or =9.0 drinks/week had a significantly lower risk of type 2 diabetes mellitus compared with abstainers (hazard ratio = 0.47, 95% confidence interval (CI): 0.27, 0.81). Adjustment for selected nutrients had little effect on the hazard ratio, whereas adjustment for dietary pattern variables by factor analysis significantly shifted the hazard ratio away from null (hazard ratio = 0.33, 95% CI: 0.17, 0.64) by 40.0% (95% CI: 16.8, 57.0; P = 0.002). Dietary pattern variables by partial least squares showed similar results. Therefore, the observed inverse association, consistent with past studies, was confounded by dietary patterns, and this confounding was not captured by individual nutrient adjustment. The data suggest that alcohol intake, not dietary patterns associated with alcohol intake, is responsible for the observed inverse association with type 2 diabetes mellitus risk.

The impact of confounder selection in propensity scores when applied to prospective cohort studies in pregnancy.

PubMed

Xu, Ronghui; Hou, Jue; Chambers, Christina D

2018-06-01

Our work was motivated by small cohort studies on the risk of birth defects in infants born to pregnant women exposed to medications. We controlled for confounding using propensity scores (PS). The extremely rare events setting renders the matching or stratification infeasible. In addition, the PS itself may be formed via different approaches to select confounders from a relatively long list of potential confounders. We carried out simulation experiments to compare different combinations of approaches: IPW or regression adjustment, with 1) including all potential confounders without selection, 2) selection based on univariate association between the candidate variable and the outcome, 3) selection based on change in effects (CIE). The simulation showed that IPW without selection leads to extremely large variances in the estimated odds ratio, which help to explain the empirical data analysis results that we had observed. Copyright © 2018 Elsevier Inc. All rights reserved.

An evidence-based approach to globally assess the covariate-dependent effect of the MTHFR single nucleotide polymorphism rs1801133 on blood homocysteine: a systematic review and meta-analysis.

PubMed

Jin, Huifeng; Cheng, Haojie; Chen, Wei; Sheng, Xiaoming; Levy, Mark A; Brown, Mark J; Tian, Junqiang

2018-05-01

The single nucleotide polymorphism of the gene 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T (or rs1801133) is the most established genetic factor that increases plasma total homocysteine (tHcy) and consequently results in hyperhomocysteinemia. Yet, given the limited penetrance of this genetic variant, it is necessary to individually predict the risk of hyperhomocysteinemia for an rs1801133 carrier. We hypothesized that variability in this genetic risk is largely due to the presence of factors (covariates) that serve as effect modifiers, confounders, or both, such as folic acid (FA) intake, and aimed to assess this risk in the complex context of these covariates. We systematically extracted from published studies the data on tHcy, rs1801133, and any previously reported rs1801133 covariates. The resulting metadata set was first used to analyze the covariates' modifying effect by meta-regression and other statistical means. Subsequently, we controlled for this modifying effect by genotype-stratifying tHcy data and analyzed the variability in the risk resulting from the confounding of covariates. The data set contains data on 36 rs1801133 covariates that were collected from 114,799 participants and 256 qualified studies, among which 6 covariates (sex, age, race, FA intake, smoking, and alcohol consumption) are the most frequently informed and therefore included for statistical analysis. The effect of rs1801133 on tHcy exhibits significant variability that can be attributed to effect modification as well as confounding by these covariates. Via statistical modeling, we predicted the covariate-dependent risk of tHcy elevation and hyperhomocysteinemia in a systematic manner. We showed an evidence-based approach that globally assesses the covariate-dependent effect of rs1801133 on tHcy. The results should assist clinicians in interpreting the rs1801133 data from genetic testing for their patients. Such information is also important for the public, who increasingly receive genetic data from commercial services without interpretation of its clinical relevance. This study was registered at Research Registry with the registration number reviewregistry328.

The Combined Effects of Measurement Error and Omitting Confounders in the Single-Mediator Model

PubMed Central

Fritz, Matthew S.; Kenny, David A.; MacKinnon, David P.

2016-01-01

Mediation analysis requires a number of strong assumptions be met in order to make valid causal inferences. Failing to account for violations of these assumptions, such as not modeling measurement error or omitting a common cause of the effects in the model, can bias the parameter estimates of the mediated effect. When the independent variable is perfectly reliable, for example when participants are randomly assigned to levels of treatment, measurement error in the mediator tends to underestimate the mediated effect, while the omission of a confounding variable of the mediator to outcome relation tends to overestimate the mediated effect. Violations of these two assumptions often co-occur, however, in which case the mediated effect could be overestimated, underestimated, or even, in very rare circumstances, unbiased. In order to explore the combined effect of measurement error and omitted confounders in the same model, the impact of each violation on the single-mediator model is first examined individually. Then the combined effect of having measurement error and omitted confounders in the same model is discussed. Throughout, an empirical example is provided to illustrate the effect of violating these assumptions on the mediated effect. PMID:27739903

Pediatric sleep problems and social-emotional problems. A population-based study.

PubMed

Hysing, Mari; Sivertsen, Børge; Garthus-Niegel, Susan; Eberhard-Gran, Malin

2016-02-01

To examine the association between sleep and social-emotional development in two-year-old toddlers. The study is part of a longitudinal cohort study, the Akershus Birth Cohort Study, which targeted all women giving birth at Akershus University Hospital in Norway. The current study is from the fourth round of the study, including 2014 women two years after delivery. The Brief Infant Sleep Questionnaire (BISQ) and the Ages and Stages Questionnaire: Social Emotional (ASQ:SE) were filled out by the mothers and were used to assess toddler sleep, and social-emotional development, respectively. Other domains of development (communication problems, gross motor problems, and fine motor problems) were assessed with the Ages and Stages Questionnaire (ASQ). Confirmatory factor analysis was conducted on the ASQ:SE, and logistic regression analyses were used to examine both crude associations between sleep variables and social-emotional problems, and adjusting for potential confounders. The mean sleep duration of the toddlers was 12h and 27 min; the majority of the children (54%) had 1-2 awakenings per night, while 10% of the children had a sleep onset latency of more than 30 min. All sleep parameters, including short sleep duration, nocturnal awakenings and sleep onset problems, were significantly associated with social-emotional problems in a dose-response manner. For example, sleeping less than 11h per night was associated with a five-fold increase in the odds of social-emotional problems, compared to sleeping 13-14 h per night. Adjusting for potential confounders, including maternal age, maternal education, marital status, parity, gestational age, child birth-weight and other developmental problems, did not, or only slightly, attenuate the associations between any of the sleep variables and social-emotional problems. Short sleep duration, nocturnal awakenings and sleep onset problems were all associated with higher odds of social-emotional problems, even after accounting for developmental problems and demographic factors. Thus, a broad assessment of sleep and social-emotional problems when toddlers present with either can be useful. Copyright © 2016. Published by Elsevier Inc.

Biasogram: Visualization of Confounding Technical Bias in Gene Expression Data

PubMed Central

Krzystanek, Marcin; Szallasi, Zoltan; Eklund, Aron C.

2013-01-01

Gene expression profiles of clinical cohorts can be used to identify genes that are correlated with a clinical variable of interest such as patient outcome or response to a particular drug. However, expression measurements are susceptible to technical bias caused by variation in extraneous factors such as RNA quality and array hybridization conditions. If such technical bias is correlated with the clinical variable of interest, the likelihood of identifying false positive genes is increased. Here we describe a method to visualize an expression matrix as a projection of all genes onto a plane defined by a clinical variable and a technical nuisance variable. The resulting plot indicates the extent to which each gene is correlated with the clinical variable or the technical variable. We demonstrate this method by applying it to three clinical trial microarray data sets, one of which identified genes that may have been driven by a confounding technical variable. This approach can be used as a quality control step to identify data sets that are likely to yield false positive results. PMID:23613961

Mindful attention and awareness mediate the association between age and negative affect.

PubMed

Raes, An K; Bruyneel, Lynn; Loeys, Tom; Moerkerke, Beatrijs; De Raedt, Rudi

2015-03-01

Later life is often accompanied by experiences of loss and bereavement in several life domains. In spite of this, older adults experience less negative affect than their younger counterparts. Several explanations for this paradoxical finding have been put forward, but the mechanisms underlying the association between age and negative affect remain largely unclear. In the present study, we propose that mindfulness may be an important mediator of this association. A cross-sectional sample of 507 participants (age range 18-85 years) was used to investigate this question. Participants completed a range of self-report questionnaires on demographic variables, mindfulness, affect, quality of life (QoL), and personality. In our mediation analysis, we used an advanced statistical technique called G-estimation to control for the impact of confounding variables such as personality dimensions and QoL. Our findings indicate that the age-related decrease in negative affect is mediated by mindfulness. The results remain significant when we control for QoL and personality. These findings imply that mindfulness skills may be an important link between age and negative affect. Implications of these findings for the understanding of the well-being paradox are discussed. © The Author 2013. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Age-related decline in cognitive control: the role of fluid intelligence and processing speed

PubMed Central

2014-01-01

Background Research on cognitive control suggests an age-related decline in proactive control abilities whereas reactive control seems to remain intact. However, the reason of the differential age effect on cognitive control efficiency is still unclear. This study investigated the potential influence of fluid intelligence and processing speed on the selective age-related decline in proactive control. Eighty young and 80 healthy older adults were included in this study. The participants were submitted to a working memory recognition paradigm, assessing proactive and reactive cognitive control by manipulating the interference level across items. Results Repeated measures ANOVAs and hierarchical linear regressions indicated that the ability to appropriately use cognitive control processes during aging seems to be at least partially affected by the amount of available cognitive resources (assessed by fluid intelligence and processing speed abilities). Conclusions This study highlights the potential role of cognitive resources on the selective age-related decline in proactive control, suggesting the importance of a more exhaustive approach considering the confounding variables during cognitive control assessment. PMID:24401034

Ocular dimensions in relation to auxological data in a sample of Swedish children aged 4-15 years.

PubMed

Raffa, Lina H; Hellström, Ann; Aring, Eva; Andersson, Susann; Grönlund, Marita Andersson

2014-11-01

The purpose was to characterize normal growth patterns of ocular and optical components and to relate them to auxological data in a sample of Swedish children aged 4-15 years. A prospective cross-sectional study was carried out in 143 Swedish children with a mean age of 9.8 years. Variables including gestational age (GA), weight, length and head circumference (HCF) at birth and at the time of assessment were registered. Visual acuity (VA), cycloplegic refraction and biometric measures were obtained. Palpebral fissure length and inner canthal distance were measured. Optic disc morphology as seen on fundus photographs was analysed. Children born more mature, with male predilection, were found to have deeper anterior and vitreous chamber depths, longer axial lengths and thinner crystalline lens thickness. No correlations were found between ocular biometric measurements and VA or refraction after adjustment for confounding variables. Inner canthal distance was significantly correlated with birth length (p = 0.03), height, weight, BMI and HCF (p = 0.0008, p = 0.0007, p = 0.037, and p = 0.04, respectively) at time of assessment. Total axial length was found to be significantly correlated with GA (p = 0.0226) and length at assessment in girls (p = 0.0084). Right optic disc and rim areas decreased with increasing age (p = 0.0078 and p = 0.0107, respectively); however, optic disc parameters were not dependent on any other variable. These normative values may serve as a basis for the ocular findings and their relationship to auxological data in Caucasian children aged 4-15 years, as well as for future comparison in patients with paediatric ocular pathologies. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Associations between otitis media and child behavioural and learning difficulties: Results from a Danish cohort.

PubMed

Niclasen, J; Obel, C; Homøe, P; Kørvel-Hanquist, A; Dammeyer, J

2016-05-01

Findings from studies investigating early childhood episodes of otitis media (OM) and developmental outcomes are inconclusive. This may in part be because large-scale prospective studies controlling for relevant confounding factors are sparse. The present study investigates associations between OM in early childhood and later behavioural and learning difficulties controlling for relevant confounding factors. The study applied data from the Aarhus Birth Cohort's 10-12-year-old follow-up (N=7578). Associations between retrospective parent-reported OM (no OM; 1-3 episodes of OM with/without tympanostomy tubes; 4+ OM episodes without tympanostomy tubes and; 4+ OM episodes with tympanostomy tubes) one the one hand, and parent- and teacher-reported scores on the Strengths and Difficulties Questionnaire (SDQ) and parent-reported academic difficulties on the other hand, were investigated. The following variables were controlled for: parental educational level, maternal and paternal school problems, parental post-natal smoking, breastfeeding, and age at which the child started walking. All analyses were stratified by gender. Large differences in background characteristics were observed for the group of children with 4+ OM episodes with tympanostomy tubes compared to the no OM group. After controlling for relevant confounders, negative associations were consistently observed for the group of children with 4+ episodes of OM with tympanostomy tubes compared to the group of children without OM. This was particularly so for girls. The findings suggest an association between 4+ episodes of early OM with tympanostomy tubes and behavioural and learning difficulties later in childhood. The large inter-group differences, i.e. impact of residual and unmeasured confounding factors, may in part explain the observed associations and underline the need to include these in future studies. Copyright © 2016. Published by Elsevier Ireland Ltd.

Cannabis Use, Polysubstance Use, and Psychosis Spectrum Symptoms in a Community-Based Sample of US Youth

PubMed Central

Jones, Jason D.; Calkins, Monica E.; Scott, J. Cobb; Bach, Emily C.; Gur, Raquel E.

2017-01-01

Purpose To examine how cannabis use and polysubstance use among cannabis users relate to psychosis spectrum (PS) symptoms in a large community-based sample of US youth. Methods 4,171 youth (age 14–21; mean=16.90, SD=1.85; 55% female) from the Philadelphia Neurodevelopmental Cohort (PNC) completed assessments of substance use, PS symptoms, and confounding variables (e.g., demographics, comorbid psychopathology, trauma exposure). Results After adjusting for confounds, cannabis use by itself was not associated with increased odds of being classified as “psychosis spectrum.” However, cannabis use in combination with tobacco or other substance use was associated with increased odds of PS classification (adjusted odds ratios [ORs] = 1.37 to 1.76). Follow-up symptom-level analyses revealed that cannabis use in combination with other substances was associated with subclinical positive symptoms (ORs=1.95 and 2.24) and frequent cannabis use was associated with subclinical negative/disorganized symptoms (OR=2.14). However, these symptom-level findings were reduced to trends after correction for multiple comparisons. Neither cannabis use nor polysubstance use was associated with threshold delusions or hallucinations. Conclusions After adjusting for important confounds, there was minimal evidence for associations between cannabis use by itself and PS symptoms. More compelling evidence emerged for associations between polysubstance use among cannabis users and PS symptoms. This study highlights the importance of considering polysubstance use and confounds when examining associations between cannabis use and PS symptoms. Further longitudinal research is necessary to determine whether these findings represent causal associations or shared genetic and/or environmental vulnerability for substance use and PS symptoms. PMID:28318911

Cannabis Use, Polysubstance Use, and Psychosis Spectrum Symptoms in a Community-Based Sample of U.S. Youth.

PubMed

Jones, Jason D; Calkins, Monica E; Scott, J Cobb; Bach, Emily C; Gur, Raquel E

2017-06-01

To examine how cannabis use and polysubstance use among cannabis users relate to psychosis spectrum (PS) symptoms in a large community-based sample of U.S. youth. Four thousand one hundred seventy-one youths (aged 14-21 years; mean = 16.90 years, SD = 1.85; 55% female) from the Philadelphia Neurodevelopmental Cohort completed assessments of substance use, PS symptoms, and confounding variables (e.g., demographics, comorbid psychopathology, and trauma exposure). After adjusting for confounds, cannabis use by itself was not associated with increased odds of being classified as "psychosis spectrum." However, cannabis use in combination with tobacco or other substance use was associated with increased odds of PS classification (adjusted odds ratios [ORs] = 1.37-1.76). Follow-up symptom-level analyses revealed that cannabis use in combination with other substances was associated with subclinical positive symptoms (ORs = 1.95 and 2.24) and frequent cannabis use was associated with subclinical negative/disorganized symptoms (OR = 2.14). However, these symptom-level findings were reduced to trends after correction for multiple comparisons. Neither cannabis use nor polysubstance use was associated with threshold delusions or hallucinations. After adjusting for important confounds, there was minimal evidence for associations between cannabis use by itself and PS symptoms. More compelling evidence emerged for associations between polysubstance use among cannabis users and PS symptoms. This study highlights the importance of considering polysubstance use and confounds when examining associations between cannabis use and PS symptoms. Further longitudinal research is necessary to determine whether these findings represent causal associations or shared genetic and/or environmental vulnerability for substance use and PS symptoms. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Prosociality during the transition from late adolescence to young adulthood: the role of effortful control and ego-resiliency.

PubMed

Alessandri, Guido; Luengo Kanacri, Bernadette Paula; Eisenberg, Nancy; Zuffianò, Antonio; Milioni, Michela; Vecchione, Michele; Caprara, Gian Vittorio

2014-11-01

The present prospective study examined the prediction of prosociality from effortful control and ego-resiliency from late adolescence to emerging adulthood. Participants were 476 young adults (239 males and 237 females) with a mean age of 16 years (SD = .81) at T1, 18 years (SD = .83) at T2, 20 years (SD = .79) at T3, 22 years (SD = .81) at T4, and 26 years (SD = .81) at T5. Controlling for the stability of the examined variables and the effect of potential confounding variables (i.e., sex, socioeconomic status [SES], and age), results supported a model in which a temperamental dimension, effortful control, positively predicted a specific behavioral tendency (i.e., prosociality) indirectly through mediation by a personality factor (i.e., ego-resiliency). Practical implications of the results are discussed in terms of the importance of early prevention efforts designed to enhance the capacity to cope effectively with emotional reactions and difficult situations. © 2014 by the Society for Personality and Social Psychology, Inc.

Effects of bilingualism on white matter integrity in older adults.

PubMed

Anderson, John A E; Grundy, John G; De Frutos, Jaisalmer; Barker, Ryan M; Grady, Cheryl; Bialystok, Ellen

2018-02-15

Bilingualism can delay the onset of dementia symptoms and has thus been characterized as a mechanism for cognitive or brain reserve, although the origin of this reserve is unknown. Studies with young adults generally show that bilingualism is associated with a strengthening of white matter, but there is conflicting evidence for how bilingualism affects white matter in older age. Given that bilingualism has been shown to help stave off the symptoms of dementia by up to four years, it is crucial that we clarify the mechanism underlying this reserve. The current study uses diffusion tensor imaging (DTI) to compare monolinguals and bilinguals while carefully controlling for potential confounds (e.g., I.Q., MMSE, and demographic variables). We show that group differences in Fractional Anisotropy (FA) and Radial Diffusivity (RD) arise from multivariable interactions not adequately controlled for by sequential bivariate testing. After matching and statistically controlling for confounds, bilinguals still had greater axial diffusivity (AD) in the left superior longitudinal fasciculus than monolingual peers, supporting a neural reserve account for healthy older bilinguals. Copyright © 2017 Elsevier Inc. All rights reserved.

Self-reported Vitamin Supplementation in Early Pregnancy and Risk of Miscarriage

PubMed Central

Olshan, Andrew F.; Herring, Amy H.; Savitz, David A.; Siega-Riz, Anna Maria; Hartmann, Katherine E.

2009-01-01

Miscarriage is a common and poorly understood adverse pregnancy outcome. In this study, the authors sought to evaluate the relation between self-reported use of prenatal vitamins in early pregnancy and the risk of miscarriage. Between 2000 and 2008, 4,752 US women were prospectively enrolled in Right From the Start. Information about vitamin use was obtained from a first-trimester interview. Discrete-time hazard models were used, candidate confounders were assessed, and the following variables were included in the model: study site, maternal age, gravidity, marital status, education, race/ethnicity, smoking, and use of progesterone in early pregnancy. Approximately 95% of participants reported use of vitamins during early pregnancy. A total of 524 women had a miscarriage. In the final adjusted model, any use of vitamins during pregnancy was associated with decreased odds of miscarriage (odds ratio = 0.43, 95% confidence interval: 0.30, 0.60) in comparison with no exposure. These results should be viewed in the context of a potentially preventive biologic mechanism mitigated by possible confounding by healthy behaviors and practices that are also associated with vitamin supplement use during pregnancy. PMID:19372214

Self-reported vitamin supplementation in early pregnancy and risk of miscarriage.

PubMed

Hasan, Reem; Olshan, Andrew F; Herring, Amy H; Savitz, David A; Siega-Riz, Anna Maria; Hartmann, Katherine E

2009-06-01

Miscarriage is a common and poorly understood adverse pregnancy outcome. In this study, the authors sought to evaluate the relation between self-reported use of prenatal vitamins in early pregnancy and the risk of miscarriage. Between 2000 and 2008, 4,752 US women were prospectively enrolled in Right From the Start. Information about vitamin use was obtained from a first-trimester interview. Discrete-time hazard models were used, candidate confounders were assessed, and the following variables were included in the model: study site, maternal age, gravidity, marital status, education, race/ethnicity, smoking, and use of progesterone in early pregnancy. Approximately 95% of participants reported use of vitamins during early pregnancy. A total of 524 women had a miscarriage. In the final adjusted model, any use of vitamins during pregnancy was associated with decreased odds of miscarriage (odds ratio = 0.43, 95% confidence interval: 0.30, 0.60) in comparison with no exposure. These results should be viewed in the context of a potentially preventive biologic mechanism mitigated by possible confounding by healthy behaviors and practices that are also associated with vitamin supplement use during pregnancy.

On the definition of a confounder

PubMed Central

VanderWeele, Tyler J.; Shpitser, Ilya

2014-01-01

Summary The causal inference literature has provided a clear formal definition of confounding expressed in terms of counterfactual independence. The causal inference literature has not, however, produced a clear formal definition of a confounder, as it has given priority to the concept of confounding over that of a confounder. We consider a number of candidate definitions arising from various more informal statements made in the literature. We consider the properties satisfied by each candidate definition, principally focusing on (i) whether under the candidate definition control for all “confounders” suffices to control for “confounding” and (ii) whether each confounder in some context helps eliminate or reduce confounding bias. Several of the candidate definitions do not have these two properties. Only one candidate definition of those considered satisfies both properties. We propose that a “confounder” be defined as a pre-exposure covariate C for which there exists a set of other covariates X such that effect of the exposure on the outcome is unconfounded conditional on (X, C) but such that for no proper subset of (X, C) is the effect of the exposure on the outcome unconfounded given the subset. A variable that helps reduce bias but not eliminate bias we propose referring to as a “surrogate confounder.” PMID:25544784

Assessing Omitted Confounder Bias in Multilevel Mediation Models.

PubMed

Tofighi, Davood; Kelley, Ken

2016-01-01

To draw valid inference about an indirect effect in a mediation model, there must be no omitted confounders. No omitted confounders means that there are no common causes of hypothesized causal relationships. When the no-omitted-confounder assumption is violated, inference about indirect effects can be severely biased and the results potentially misleading. Despite the increasing attention to address confounder bias in single-level mediation, this topic has received little attention in the growing area of multilevel mediation analysis. A formidable challenge is that the no-omitted-confounder assumption is untestable. To address this challenge, we first analytically examined the biasing effects of potential violations of this critical assumption in a two-level mediation model with random intercepts and slopes, in which all the variables are measured at Level 1. Our analytic results show that omitting a Level 1 confounder can yield misleading results about key quantities of interest, such as Level 1 and Level 2 indirect effects. Second, we proposed a sensitivity analysis technique to assess the extent to which potential violation of the no-omitted-confounder assumption might invalidate or alter the conclusions about the indirect effects observed. We illustrated the methods using an empirical study and provided computer code so that researchers can implement the methods discussed.

Confounder Detection in High-Dimensional Linear Models Using First Moments of Spectral Measures.

PubMed

Liu, Furui; Chan, Laiwan

2018-06-12

In this letter, we study the confounder detection problem in the linear model, where the target variable [Formula: see text] is predicted using its [Formula: see text] potential causes [Formula: see text]. Based on an assumption of a rotation-invariant generating process of the model, recent study shows that the spectral measure induced by the regression coefficient vector with respect to the covariance matrix of [Formula: see text] is close to a uniform measure in purely causal cases, but it differs from a uniform measure characteristically in the presence of a scalar confounder. Analyzing spectral measure patterns could help to detect confounding. In this letter, we propose to use the first moment of the spectral measure for confounder detection. We calculate the first moment of the regression vector-induced spectral measure and compare it with the first moment of a uniform spectral measure, both defined with respect to the covariance matrix of [Formula: see text]. The two moments coincide in nonconfounding cases and differ from each other in the presence of confounding. This statistical causal-confounding asymmetry can be used for confounder detection. Without the need to analyze the spectral measure pattern, our method avoids the difficulty of metric choice and multiple parameter optimization. Experiments on synthetic and real data show the performance of this method.

Examining the Error of Mis-Specifying Nonlinear Confounding Effect With Application on Accelerometer-Measured Physical Activity.

PubMed

Lee, Paul H

2017-06-01

Some confounders are nonlinearly associated with dependent variables, but they are often adjusted using a linear term. The purpose of this study was to examine the error of mis-specifying the nonlinear confounding effect. We carried out a simulation study to investigate the effect of adjusting for a nonlinear confounder in the estimation of a causal relationship between the exposure and outcome in 3 ways: using a linear term, binning into 5 equal-size categories, or using a restricted cubic spline of the confounder. Continuous, binary, and survival outcomes were simulated. We examined the confounder across varying measurement error. In addition, we performed a real data analysis examining the 3 strategies to handle the nonlinear effects of accelerometer-measured physical activity in the National Health and Nutrition Examination Survey 2003-2006 data. The mis-specification of a nonlinear confounder had little impact on causal effect estimation for continuous outcomes. For binary and survival outcomes, this mis-specification introduced bias, which could be eliminated using spline adjustment only when there is small measurement error of the confounder. Real data analysis showed that the associations between high blood pressure, high cholesterol, and diabetes and mortality adjusted for physical activity with restricted cubic spline were about 3% to 11% larger than their counterparts adjusted with a linear term. For continuous outcomes, confounders with nonlinear effects can be adjusting with a linear term. Spline adjustment should be used for binary and survival outcomes on confounders with small measurement error.

Interpretational Confounding Is Due to Misspecification, Not to Type of Indicator: Comment on Howell, Breivik, and Wilcox (2007)

ERIC Educational Resources Information Center

Bollen, Kenneth A.

2007-01-01

R. D. Howell, E. Breivik, and J. B. Wilcox (2007) have argued that causal (formative) indicators are inherently subject to interpretational confounding. That is, they have argued that using causal (formative) indicators leads the empirical meaning of a latent variable to be other than that assigned to it by a researcher. Their critique of causal…

Causal diagrams and multivariate analysis III: confound it!

PubMed

Jupiter, Daniel C

2015-01-01

This commentary concludes my series concerning inclusion of variables in multivariate analyses. We take up the issues of confounding and effect modification and summarize the work we have thus far done. Finally, we provide a rough algorithm to help guide us through the maze of possibilities that we have outlined. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Impact sports and bone fractures among adolescents.

PubMed

Lynch, Kyle R; Kemper, Han C G; Turi-Lynch, Bruna; Agostinete, Ricardo R; Ito, Igor H; Luiz-De-Marco, Rafael; Rodrigues-Junior, Mario A; Fernandes, Rômulo A

2017-12-01

The objective of the present study was to investigate the effects of different sports on stress fractures among adolescents during a 9-month follow-up period. The sample was composed of 184 adolescents divided into three groups (impact sports [n = 102]; swimming [n = 35]; non-sports [n = 47]). The occurrence of stress fracture was reported by participants and coaches. As potential confounders we considered age, sex, resistance training, body composition variables and age at peak of height velocity. There were 13 adolescents who reported fractures during the 9-month period. Bone mineral density values were higher in adolescents engaged in impact sports (P-value = 0.002). Independently of confounders, the risk of stress fracture was lower in adolescents engaged in impact sports than in non-active adolescents (hazard ratio [HR] = 0.23 [95% confidence interval (CI) = 0.05 to 0.98]), while swimming practice was not associated to lower risk of fracture (HR = 0.49 [95% CI = 0.09 to 2.55]). In conclusion, the findings from this study indicate the importance of sports participation among adolescents in the reduction of stress fracture risk, especially with impact sports. More importantly, these results could be relevant for recognising adolescents in danger of not reaching their potential for peak bone mass and later an increased risk of fractures.

[Coffee consumption and type 2 diabetes mellitus].

PubMed

Radzeviciene, Lina; Ostrauskas, Rytas

2009-01-01

The aim of the study was to determine the association between coffee consumption and the risk of type 2 diabetes mellitus. A case-control study included 234 cases with newly confirmed diagnosis of type 2 diabetes mellitus and 468 controls who were free of the disease in 2001. Cases and controls were matched by gender and age (+/-5 years). Data on age, education level, occupation status, marital status, family history of diabetes, lifestyle (dietary habits, smoking habits, coffee consumption, alcohol consumption, physical activity), and stress were collected via a questionnaire. Variables were retained in models as confounders when their inclusion changed the value of the OR by more than 10% in any exposure category. Conditional logistic regression to compute the odds ratio (OR), 95% confidence interval (CI), and P for trend was used. After adjustment for possible confounders (family history of diabetes, body mass index, eating speed, morning exercise, cigarette smoking, years of education, and stress), a statistically significant relationship was observed between type 2 diabetes mellitus and coffee consumption. Individuals consuming four or more cups of coffee per day were at lower risk of 2 diabetes mellitus (OR=0.51; 95% CI, 0.27-0.97) compared to those who consumed one or less than one cup of coffee per day. Habitual coffee consumption of four or more cups per day might be related to the lower risk of type 2 diabetes mellitus.

Language outcomes at 12 years for children exposed prenatally to cocaine.

PubMed

Lewis, Barbara A; Minnes, Sonia; Short, Elizabeth J; Min, Meeyoung O; Wu, Miaoping; Lang, Adelaide; Weishampel, Paul; Singer, Lynn T

2013-10-01

In this study, the authors aimed to examine the long-term effects of prenatal cocaine exposure (PCE) on the language development of 12-year-old children using a prospective design, controlling for confounding prenatal drug exposure and environmental factors. Children who were exposed to cocaine in utero (PCE; n = 183) and children who were not exposed to cocaine (i.e., no cocaine exposure [NCE]; n = 181) were followed prospectively from birth to 12 years of age and were compared on language subtests of the Test of Language Development-Intermediate, Third Edition ( Hammill & Newcomer, 1997b), and phonological processing as measured by the Comprehensive Test of Phonological Processing ( Wagner & Torgesen, 1999). The authors evaluated the relationship of PCE to language development through a multivariate analysis of covariance and regression analyses while controlling for confounders. Results show that PCE has small effects on specific aspects of language, including syntax and phonological processing. The caregiver variables of lower maternal vocabulary, more psychological symptoms, and a poorer home environment also had consistent effects on language and phonological processing scores. These findings suggest that PCE continues to have small, subtle effects on specific aspects of language at age 12 years. Phonological processing skills were significantly related to the reading outcomes of letter-word identification, reading fluency, and reading comprehension, indicating that PCE also has small but lasting effects on the language skills that are related to later literacy skills.

Time from cervical conization to pregnancy and preterm birth.

PubMed

Himes, Katherine P; Simhan, Hyagriv N

2007-02-01

To estimate whether the time interval between cervical conization and subsequent pregnancy is associated with risk of preterm birth. Our study is a case control study nested in a retrospective cohort. Women who underwent colposcopic biopsy or conization with loop electrosurgical excision procedure, large loop excision of the transformation zone, or cold knife cone and subsequently delivered at our hospital were identified with electronic databases. Variables considered as possible confounders included maternal race, age, marital status, payor status, years of education, self-reported tobacco use, history of preterm delivery, and dimensions of cone specimen. Conization was not associated with preterm birth or any subtypes of preterm birth. Among women who underwent conization, those with a subsequent preterm birth had a shorter conization-to-pregnancy interval (337 days) than women with a subsequent term birth (581 days) (P=.004). The association between short conization-to-pregnancy interval and preterm birth remained significant when controlling for confounders including race and cone dimensions. The effect of short conization-to-pregnancy interval on subsequent preterm birth was more persistent among African Americans when compared with white women. Women with a short conization-to-pregnancy interval are at increased risk for preterm birth. Women of reproductive age who must have a conization procedure can be counseled that conceiving within 2 to 3 months of the procedure may be associated with an increased risk of preterm birth. II.

Labor patterns in twin gestations

PubMed Central

Leftwich, Heidi K.; Zaki, Mary N.; Wilkins, Isabelle; Hibbard, Judith U.

2014-01-01

Objective To compare labor progression in twin vs singleton gestations. Study Design Retrospective review of electronic database created by Consortium on Safe Labor, reflecting labor and delivery information from 12 clinical centers 2002-2008. Women with twin gestations, cephalic presentation of presenting twin, gestational age ≥34 weeks, with ≥2 cervical examinations were included. Exclusion criteria were fetal anomalies or demise. Singleton controls were selected by the same criteria. Categorical variables were analyzed by χ2; continuous by Student t test. Interval censored regression was used to determine distribution for time of cervical dilation in centimeters, or “traverse times,” and controlled for confounding factors. Repeated-measures analysis constructed mean labor curves by parity and number of fetuses. Results A total of 891 twin gestations were compared with 100,513 singleton controls. Twin gestations were more often older, white or African American, earlier gestational age, increased prepregnancy body mass index, and with lower birthweight. There was no difference in number of prior cesarean deliveries, induction, or augmentation, or epidural use. Median traverse times increased at every centimeter interval in nulliparous twins, in both unadjusted and adjusted analysis (P < .01). A similar pattern was noted for multiparas in both analyses. Labor curves demonstrated a delayed inflection point in the labor pattern for nulliparous and multiparous twin gestations. Conclusion Both nulliparous and multiparous women have slower progression of active phase labor with twins even when controlling for confounding factors. PMID:23871795

Living in stressful neighbourhoods during pregnancy: an observational study of crime rates and birth outcomes

PubMed Central

Clemens, Tom

2017-01-01

Abstract Background: Patterns of adverse birth outcomes vary spatially and there is evidence that this may relate to features of the physical environment such as air pollution. However, other social characteristics of the environment such as levels of crime are relatively understudied. This study examines the association between crime rates and birth weight and prematurity. Methods: Maternity inpatient data recorded at birth, including residential postcode, was linked to a representative 5% sample of Scottish Census data and small area crime rates from Scottish Police forces. Coefficients associated with crime were reported from crude and confounder adjusted models predicting low birth weight (< 2500 g), mean birthweight, small for gestational age and prematurity for all singleton live births. Results: Total crime rates were associated with strong and significant reductions in mean birth weight and increases in the risks of both a small for gestational age baby and premature birth. These effects, with the exception of prematurity, were robust to adjustment for individual characteristics including smoking, ethnicity and other socio-economic variables as well as area based confounders including air pollution. Mean birth weight was robust to additional adjustment for neighbourhood income deprivation. Conclusion: The level of crime in a mother’s area of residence, which may be a proxy for the degree of threat felt and therefore stress experienced, appears to be an important determinant of the risk of adverse birth outcomes. PMID:27578830

Challenges in measuring individual differences in functional connectivity using fMRI: The case of healthy aging

PubMed Central

Tsvetanov, Kamen A.; Cam‐CAN; Henson, Richard N.

2017-01-01

Abstract Many studies report individual differences in functional connectivity, such as those related to age. However, estimates of connectivity from fMRI are confounded by other factors, such as vascular health, head motion and changes in the location of functional regions. Here, we investigate the impact of these confounds, and pre‐processing strategies that can mitigate them, using data from the Cambridge Centre for Ageing & Neuroscience (www.cam-can.com). This dataset contained two sessions of resting‐state fMRI from 214 adults aged 18–88. Functional connectivity between all regions was strongly related to vascular health, most likely reflecting respiratory and cardiac signals. These variations in mean connectivity limit the validity of between‐participant comparisons of connectivity estimates, and were best mitigated by regression of mean connectivity over participants. We also showed that high‐pass filtering, instead of band‐pass filtering, produced stronger and more reliable age‐effects. Head motion was correlated with gray‐matter volume in selected brain regions, and with various cognitive measures, suggesting that it has a biological (trait) component, and warning against regressing out motion over participants. Finally, we showed that the location of functional regions was more variable in older adults, which was alleviated by smoothing the data, or using a multivariate measure of connectivity. These results demonstrate that analysis choices have a dramatic impact on connectivity differences between individuals, ultimately affecting the associations found between connectivity and cognition. It is important that fMRI connectivity studies address these issues, and we suggest a number of ways to optimize analysis choices. Hum Brain Mapp 38:4125–4156, 2017. © 2017 Wiley Periodicals, Inc. PMID:28544076

Refined carbohydrate intake in relation to non-verbal intelligence among Tehrani schoolchildren.

PubMed

Abargouei, Amin Salehi; Kalantari, Naser; Omidvar, Nasrin; Rashidkhani, Bahram; Rad, Anahita Houshiar; Ebrahimi, Azizeh Afkham; Khosravi-Boroujeni, Hossein; Esmaillzadeh, Ahmad

2012-10-01

Nutrition has long been considered one of the most important environmental factors affecting human intelligence. Although carbohydrates are the most widely studied nutrient for their possible effects on cognition, limited data are available linking usual refined carbohydrate intake and intelligence. The present study was conducted to examine the relationship between long-term refined carbohydrate intake and non-verbal intelligence among schoolchildren. Cross-sectional study. Tehran, Iran. In this cross-sectional study, 245 students aged 6-7 years were selected from 129 elementary schools in two western regions of Tehran. Anthropometric measurements were carried out. Non-verbal intelligence and refined carbohydrate consumption were determined using Raven's Standard Progressive Matrices test and a modified sixty-seven-item FFQ, respectively. Data about potential confounding variables were collected. Linear regression analysis was applied to examine the relationship between non-verbal intelligence scores and refined carbohydrate consumption. Individuals in top tertile of refined carbohydrate intake had lower mean non-verbal intelligence scores in the crude model (P < 0.038). This association remained significant after controlling for age, gender, birth date, birth order and breast-feeding pattern (P = 0.045). However, further adjustments for mother's age, mother's education, father's education, parental occupation and BMI made the association statistically non-significant. We found a significant inverse association between refined carbohydrate consumption and non-verbal intelligence scores in regression models (β = -11.359, P < 0.001). This relationship remained significant in multivariate analysis after controlling for potential confounders (β = -8.495, P = 0.038). The study provides evidence indicating an inverse relationship between refined carbohydrate consumption and non-verbal intelligence among Tehrani children aged 6-7 years. Prospective studies are needed to confirm our findings.

Childhood maltreatment preceding depressive disorder at age 18 years: A prospective Brazilian birth cohort study.

PubMed

Gallo, Erika Alejandra Giraldo; De Mola, Christian Loret; Wehrmeister, Fernando; Gonçalves, Helen; Kieling, Christian; Murray, Joseph

2017-08-01

Childhood maltreatment is linked with increased risk for mental illness in adolescence and adulthood. However, little evidence is available on whether different forms of maltreatment have specific effects, and no prospective studies in low- or middle-income countries have addressed this issue. Participants in a population-based, birth cohort study in Pelotas, Brazil (N=3715) self-reported exposure to maltreatment (emotional abuse, physical neglect, physical abuse, sexual abuse, domestic violence) in confidential questionnaires at age 15 years, and were assessed for major depression in interviews at age 18 years, using the MINI. Confounding variables concerning family characteristics were measured in interviews with mothers in the perinatal period and at age 11 years. Females exposed to emotional abuse (OR=2.7; 95%CI=1.9, 3.8) and domestic violence (OR=1.9; 95%CI=1.2, 2.9) were at increased risk for depression after adjustment for confounders and other types of maltreatment. Females exposed to two or more forms of maltreatment were at particularly high risk for depression (OR=4.1; 95%Cl=2.8, 6.1) compared with females not exposed to maltreatment. In adjusted analyses, maltreatment was not associated with depression for males. Detailed information about maltreatment such as timing and frequency was not available, and 1534 individuals were not included in the analyses, who had poorer and less educated mothers. Emotional abuse and domestic violence are strong risk factors for major depression for females. Early intervention to prevent maltreatment and its consequences is critical, especially for girls exposed to poly-maltreatment. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Prenatal diet and children's trajectories of hyperactivity-inattention and conduct problems from 3 to 8 years: the EDEN mother-child cohort.

PubMed

Galera, Cédric; Heude, Barbara; Forhan, Anne; Bernard, Jonathan Y; Peyre, Hugo; Van der Waerden, Judith; Pryor, Laura; Bouvard, Manuel-Pierre; Melchior, Maria; Lioret, Sandrine; de Lauzon-Guillain, Blandine

2018-03-24

Evidence shows that diet contributes substantially to lifelong physical and mental health. Although dietary exposure during gestation and early postnatal life is critical, human epidemiological data are limited regarding its link with children's subsequent externalizing issues. The aim of this study was to investigate the role of maternal diet during pregnancy in offspring's symptoms of hyperactivity-inattention and conduct problems from ages 3 to 8 years. We used data of 1,242 mother-child pairs from a French cohort followed up from pregnancy until the children were 8 years of age. Dietary patterns (DP) of the mother during pregnancy were assessed with food frequency questionnaires. Children's externalizing behavior was assessed with the Strength and Difficulties Questionnaire at ages 3, 5, and 8 years, from which trajectories of hyperactivity-inattention symptoms and conduct problems were derived. We conducted multivariable logistic models to study associations adjusted for a range of potential confounders. Results showed significant relationships between maternal 'low Healthy diet' (adjusted Odds Ratio (aOR) = 1.61; IC 95%: 1.09-2.37) and 'high Western diet' (aOR = 1.67; IC 95%: 1.13-2.47) during pregnancy and children's trajectories of high symptoms of hyperactivity-inattention. The associations took into account relevant confounders such as DP of the children at age 2 years, maternal stress and depression, gestational diabetes, and socioeconomic variables. Maternal diet during pregnancy was independently associated with children's hyperactivity-inattention symptoms but not with conduct problems. Early prevention addressing lifestyle should specifically target diet in pregnant women. © 2018 Association for Child and Adolescent Mental Health.

Polychlorinated biphenyl exposure and effects in transformer repair workers.

PubMed Central

Emmett, E A

1985-01-01

Fifty-five present and past transformer repair workers exposed to polychlorinated biphenyls (PCBs) and 56 unexposed comparison workers were evaluated in a clinical-epidemiologic study. The groups were similar in most demographic variables. Adipose tissue lipid and serum PCBs concentrations were higher in current exposed workers (geometric means adipose 2.1 ppm, serum 12.2 ppb). Concentrations in comparison (0.6 ppm and 4.6 ppb) and previously exposed (0.83 ppm and 5.9 ppb) workers were lower. Statistically significant differences in serum albumin and lactic dehydrogenase, but not in other liver function tests, were seen between the exposed and comparison groups; however, after adjustment for confounding variables, no correlations were observed between liver function tests and either adipose or serum PCBs concentrations. Statistically significant correlation both before and after adjustment for confounding variables were seen with adipose PCBs and 24-hr urinary 17-hydroxycorticosteroid excretion and with serum PCBs and serum gamma-glutamyl transpeptidase. Both associations could reflect microsomal enzyme induction among other possibilities. No differences were seen in fasting serum triglycerides, total cholesterol, LDL, HDL or VLDL cholesterol between the two exposure groups. A statistically significant correlation between serum PCBs and serum triglycerides, total cholesterol, and VLDL cholesterol was removed by adjusting for confounding variables. No correlation was seen between adipose PCBs concentrations and any serum lipid component. Partition phenomena could account for these findings.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2863134

On causal interpretation of race in regressions adjusting for confounding and mediating variables

PubMed Central

VanderWeele, Tyler J.; Robinson, Whitney R.

2014-01-01

We consider several possible interpretations of the “effect of race” when regressions are run with race as an exposure variable, controlling also for various confounding and mediating variables. When adjustment is made for socioeconomic status early in a person’s life, we discuss under what contexts the regression coefficients for race can be interpreted as corresponding to the extent to which a racial inequality would remain if various socioeconomic distributions early in life across racial groups could be equalized. When adjustment is also made for adult socioeconomic status, we note how the overall racial inequality can be decomposed into the portion that would be eliminated by equalizing adult socioeconomic status across racial groups and the portion of the inequality that would remain even if adult socioeconomic status across racial groups were equalized. We also discuss a stronger interpretation of the “effect of race” (stronger in terms of assumptions) involving the joint effects of race-associated physical phenotype (e.g. skin color), parental physical phenotype, genetic background and cultural context when such variables are thought to be hypothetically manipulable and if adequate control for confounding were possible. We discuss some of the challenges with such an interpretation. Further discussion is given as to how the use of selected populations in examining racial disparities can additionally complicate the interpretation of the effects. PMID:24887159

Factors Affecting the Clinical Success Rate of Miniscrew Implants for Orthodontic Treatment.

PubMed

Jing, Zheng; Wu, Yeke; Jiang, Wenlu; Zhao, Lixing; Jing, Dian; Zhang, Nian; Cao, Xiaoqing; Xu, Zhenrui; Zhao, Zhihe

2016-01-01

The purpose of this study was to evaluate the various factors that influence the success rate of miniscrew implants used as orthodontic anchorage. Potential confounding variables examined were sex, age, vertical (FMA) and sagittal (ANB) skeletal facial pattern, site of placement (labial and buccal, palatal, and retromandibular triangle), arch of placement (maxilla and mandible), placement soft tissue type, oral hygiene, diameter and length of miniscrew implants, insertion method (predrilled or drill-free), angle of placement, onset and strength of force application, and clinical purpose. The correlations between success rate and overall variables were investigated by logistic regression analysis, and the effect of each variable on the success rate was utilized by variance analysis. One hundred fourteen patients were included with a total of 253 miniscrew implants. The overall success rate was 88.54% with an average loading period of 9.5 months in successful cases. Age, oral hygiene, vertical skeletal facial pattern (FMA), and general placement sites (maxillary and mandibular) presented significant differences in success rates both by logistic regression analysis and variance analysis (P < .05). To minimize the failure of miniscrew implants, proper oral hygiene instruction and effective supervision should be given for patients, especially young (< 12 years) high-angle patients with miniscrew implants placed in the mandible.

Self-esteem and violence: testing links between adolescent self-esteem and later hostility and violent behavior.

PubMed

Boden, Joseph M; Fergusson, David M; Horwood, L John

2007-11-01

This study investigated the relationship between self-esteem in adolescence and later violent offending and hostility via self- and other-report, examining data from a birth cohort of over 1,000 New Zealand young adults studied to age 25. Lower levels of self-esteem at age 15 were related to greater risks of violent offending and higher levels of hostility at ages 18, 21, and 25. Adjustment for potentially confounding factors reduced the strength of the associations between self-esteem at age 15 and both self- and other-reported violent offending and other-reported hostility at ages 18, 21, and 25 to statistically non-significant levels. The association between self-esteem at age 15 and later self-reported hostility remained statistically significant, but was small in magnitude. A similar pattern of results were obtained using self-esteem at age 10 as the predictor variable in place of the age 15 measure. In addition, a persistent association was found between unstable high self-esteem and self-reported violent offending. The results suggest that self-esteem level plays a limited role in the understanding of violent behavior.

African American Race is an Independent Risk Factor in Survival from Initially Diagnosed Localized Breast Cancer

PubMed Central

Wieder, Robert; Shafiq, Basit; Adam, Nabil

2016-01-01

BACKGROUND: African American race negatively impacts survival from localized breast cancer but co-variable factors confound the impact. METHODS: Data sets were analyzed from the Surveillance, Epidemiology and End Results (SEER) directories from 1973 to 2011 consisting of patients with designated diagnosis of breast adenocarcinoma, race as White or Caucasian, Black or African American, Asian, American Indian or Alaskan Native, Native Hawaiian or Pacific Islander, age, stage I, II or III, grade 1, 2 or 3, estrogen receptor or progesterone receptor positive or negative, marital status as single, married, separated, divorced or widowed and laterality as right or left. The Cox Proportional Hazards Regression model was used to determine hazard ratios for survival. Chi square test was applied to determine the interdependence of variables found significant in the multivariable Cox Proportional Hazards Regression analysis. Cells with stratified data of patients with identical characteristics except African American or Caucasian race were compared. RESULTS: Age, stage, grade, ER and PR status and marital status significantly co-varied with race and with each other. Stratifications by single co-variables demonstrated worse hazard ratios for survival for African Americans. Stratification by three and four co-variables demonstrated worse hazard ratios for survival for African Americans in most subgroupings with sufficient numbers of values. Differences in some subgroupings containing poor prognostic co-variables did not reach significance, suggesting that race effects may be partly overcome by additional poor prognostic indicators. CONCLUSIONS: African American race is a poor prognostic indicator for survival from breast cancer independent of 6 associated co-variables with prognostic significance. PMID:27698895

Demographic factors, fatigue, and driving accidents: An examination of the published literature.

PubMed

Di Milia, Lee; Smolensky, Michael H; Costa, Giovanni; Howarth, Heidi D; Ohayon, Maurice M; Philip, Pierre

2011-03-01

This article reviews the literature pertaining to the association between demographic variables (e.g., age, sex, race, socio-economic status) with fatigue, and when feasible, accident risk. It also explores their potential influence and interaction with some working arrangements, commute time, personality characteristics, and circadian chronotype. Fatigue has been implicated in a range of impairments that can have detrimental effects on individuals, and it is differentially associated with conventional demographic variables. However, several major methodological limitations prevent clear conclusions. First, there is absence of a shared definition both within and across disciplines. Second, although fatigue has been investigated using a variety of diverse designs, they have either been too weak to substantiate causality or lacked ecological validity. Third, while both subjective and objective measures have been used as dependent variables, fatigue has been more often found to be more strongly linked with the former. Fourth, with the exception of age and sex, the influence of other demographic variables is unknown, since they have not yet been concomitantly assessed. In instances when they have been assessed and included in statistical analyses, they are considered as covariates or confounders; thus, their contribution to the outcome variable is controlled for, rather than being a planned aspect of investigation. Because the interaction of demographic factors with fatigue is largely a neglected area of study, we recommend greater interdisciplinary collaborations, incorporation of multiple demographic variables as independent factors, and use of within-participant analyses. These recommendations would provide meaningful results that may be used to inform public policy and preventive strategies. Copyright © 2009 Elsevier Ltd. All rights reserved.

Gender-related mental health differences between refugees and non-refugee immigrants - a cross-sectional register-based study

PubMed Central

2011-01-01

Background Being an immigrant in a high-income country is a risk factor for severe mental ill health. Studies on mental ill health among immigrants have found significant differences in mental health outcome between immigrants from high income countries and low-income countries. Being an asylum seeker or a refugee is also associated with mental ill health. This study aimed to assess if there is a difference in mental ill health problems between male and female refugee and non-refugee immigrants from six low-income countries in Sweden. Methods A cross-sectional, population-based study design was used comparing refugees with non-refugees. The study size was determined by the number of persons in Sweden fulfilling the inclusion criteria at the time of the study during 2006. Outcome: Mental ill health, as measured with the proxy variable psychotropic drugs purchased. Refugee/Non-refugee: Sweden grants asylum to refugees according to the Geneva Convention and those with a well-grounded fear of death penalty, torture or who need protection due to an internal or external armed conflict or an environmental disaster. The non-refugees were all family members of those granted asylum in Sweden. Covariates: Gender and origin. Potential confounders: Age, marital status, education and duration of stay in Sweden. Background variables were analysed using chi square tests. The association between outcome, exposure and possible confounders was analysed using logistic regression analyses. Multiple logistic regression analysis was used to adjust for potential confounders. Results The study population comprised 43,168 refugees and non-refugees, of whom 20,940 (48.5%) were women and 24,403 (56.5%) were refugees. Gender, age, origin, marital status and education were all associated with the outcome. For female, but not male, refugees there was a significantly higher likelihood of purchasing psychotropic drugs than non-refugees (OR = 1.27, 95% CI = 1.15 - 1.40). Conclusions Female refugees from low-income countries seem to be a risk group among immigrant women from low-income countries, whereas male refugees had the same risk patterns as non-refugee immigrants from low-income countries. This underlines the need for training of clinicians in order to focus on pre-migration stress and the asylum process, among female newcomers. PMID:21435212

Gender-related mental health differences between refugees and non-refugee immigrants--a cross-sectional register-based study.

PubMed

Hollander, Anna-Clara; Bruce, Daniel; Burström, Bo; Ekblad, Solvig

2011-03-24

Being an immigrant in a high-income country is a risk factor for severe mental ill health. Studies on mental ill health among immigrants have found significant differences in mental health outcome between immigrants from high income countries and low-income countries. Being an asylum seeker or a refugee is also associated with mental ill health. This study aimed to assess if there is a difference in mental ill health problems between male and female refugee and non-refugee immigrants from six low-income countries in Sweden. A cross-sectional, population-based study design was used comparing refugees with non-refugees. The study size was determined by the number of persons in Sweden fulfilling the inclusion criteria at the time of the study during 2006. Mental ill health, as measured with the proxy variable psychotropic drugs purchased. Refugee/Non-refugee: Sweden grants asylum to refugees according to the Geneva Convention and those with a well-grounded fear of death penalty, torture or who need protection due to an internal or external armed conflict or an environmental disaster. The non-refugees were all family members of those granted asylum in Sweden. Covariates: Gender and origin. Potential confounders: Age, marital status, education and duration of stay in Sweden. Background variables were analysed using chi square tests. The association between outcome, exposure and possible confounders was analysed using logistic regression analyses. Multiple logistic regression analysis was used to adjust for potential confounders. The study population comprised 43,168 refugees and non-refugees, of whom 20,940 (48.5%) were women and 24,403 (56.5%) were refugees. Gender, age, origin, marital status and education were all associated with the outcome. For female, but not male, refugees there was a significantly higher likelihood of purchasing psychotropic drugs than non-refugees (OR = 1.27, 95% CI = 1.15-1.40). Female refugees from low-income countries seem to be a risk group among immigrant women from low-income countries, whereas male refugees had the same risk patterns as non-refugee immigrants from low-income countries. This underlines the need for training of clinicians in order to focus on pre-migration stress and the asylum process, among female newcomers.

Access to health programs at the workplace and the reduction of work presenteeism: a population-based cross-sectional study.

PubMed

Bustillos, Arnaldo Sanchez; Trigoso, Oswaldo Ortiz

2013-11-01

To examine access to health programs at workplace as a determinant of presenteeism among adults. Data source was a subsample of the 2009-2010 Canadian Community Health Survey. The outcome was self-reported reduced activities at work (presenteeism). The explanatory variable was self-reported access to a health program at workplace. Logistic regression was used to measure the association between outcome and explanatory variables adjusting for potential confounders. Adjusting for sex, age, education, income, work stress, and chronic conditions, presenteeism was not associated with having access to a health program at workplace (adjusted odds ratio, 1.23; 95% confidence interval, 0.91 to 1.65). The odds of presenteeism were higher in workers who reported high work stress and those with chronic medical conditions. This study found that access to health programs at workplace is not significantly associated with a decline in presenteeism.

Do patient and practice characteristics confound age-group differences in preferences for general practice care? A quantitative study

PubMed Central

2013-01-01

Background Previous research showed inconsistent results regarding the relationship between the age of patients and preference statements regarding GP care. This study investigates whether elderly patients have different preference scores and ranking orders concerning 58 preference statements for GP care than younger patients. Moreover, this study examines whether patient characteristics and practice location may confound the relationship between age and the categorisation of a preference score as very important. Methods Data of the Consumer Quality Index GP Care were used, which were collected in 32 general practices in the Netherlands. The rank order and preference score were calculated for 58 preference statements for four age groups (0–30, 31–50, 51–74, 75 years and older). Using chi-square tests and logistic regression analyses, it was investigated whether a significant relationship between age and preference score was confounded by patient characteristics and practice location. Results Elderly patients did not have a significant different ranking order for the preference statements than the other three age groups (r = 0.0193; p = 0.41). However, in 53% of the statements significant differences were found in preference score between the four age groups. Elderly patients categorized significantly less preference statements as ‘very important’. In most cases, the significant relationships were not confounded by gender, education, perceived health, the number of GP contacts and location of the GP practice. Conclusion The preferences of elderly patients for GP care concern the same items as younger patients. However, their preferences are less strong, which cannot be ascribed to gender, education, perceived health, the number of GP contacts and practice location. PMID:23800156

Factors that contribute to biomarker responses in humans including a study in individuals taking Vitamin C supplementation.

PubMed

Anderson, D

2001-09-01

It is possible in many situations to identify humans exposed to potentially toxic materials in the workplace and in the environment. As in most human studies, there tends to be a high degree of interindividual variability in response to chemical insults. Some non-exposed control individuals exhibit as high a level of damage as some exposed individuals and some of these have levels of damage as low as many of the controls. Thus, it is only the mean values of the groups that can substantiate an exposure-related problem; the data on an individual basis are still of limited use. While human lymphocytes remain the most popular cell type for monitoring purposes, sperm, buccal, nasal, epithelial and placental cells are also used. However, for interpretation of responses, the issue of confounding factors must be addressed. There are endogenous confounding factors, such as age, gender, and genetic make-up and exogenous ones, including lifestyle habits (smoking, drinking, etc.) There are biomarkers of exposure, effect/response and susceptibility and the last may be influenced by the genotype and polymorphism genes existing in a population. From our own studies, confounding effects on cytogenetic damage and ras oncoproteins will be considered in relation to workers exposed to vinyl chloride and petroleum emissions and to volunteers taking Vitamin C supplementation. Smoking history, exposure and duration of employment affected the worker studies. For petroleum emissions, so did gender and season of exposure. For the non-smoking volunteer Vitamin C supplementation study, cholesterol levels, plasma Vitamin C levels, lipid peroxidation products and DNA damage in the Comet assay were also measured. Gender affected differences in Vitamin C levels, antioxidant capacity and the number of chromosome aberrations induced by bleomycin challenge in vitro. The results were the same for both high and low cholesterol subjects. The relationship between biomarkers and the various factors which affect them is complex. Sometimes the variables are not completely independent of each other.

Association of tic disorders with poor academic performance in central Spain: a population-based study.

PubMed

Cubo, Esther; Trejo, José; Ausín, Vanesa; Sáez, Sara; Delgado, Vanesa; Macarrón, Jesus; Cordero, José; Louis, Elan D; Kompoliti, Katie; Benito-León, Julián

2013-07-01

To analyze the association between tic disorders and poor academic performance in school-aged children. This was a cross-sectional, observational study conducted in a randomly selected sample of mainstream school-aged children (aged 6-16 years). The sampling frame included different types of schools and educational levels. Children with poor academic performance (eg, repeating a grade, special needs), and tic disorders (defined based on Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision criteria) were identified. Children with and without tics and children with and without poor academic performance were compared in terms of clinical features (ie, medical history and neurologic and psychiatric comorbidities), school, and environmental characteristics. Logistic regression analyses were performed using school performance (dependent variable) and tic disorders (independent variable), after adjusting for confounding variables. The study cohort comprised 1867 children (mean age, 10.9 + 2.9 years; 1007 males [53.9%]). Tics were present in 162 children (8.6%), and poor academic performance was noted in 223 (11.9%). Overall poor academic performance was associated with age (OR, 1.71; P < .0001), television viewing (OR, 5.33; P = .04), attention deficit hyperactivity disorder (OR, 1.38; P < .0001), and family history of school dysfunction (OR, 2.43; P = .02) and was negatively associated with higher IQ score (OR, 0.90; P < .0001) and tic disorders (OR, 0.29; P = .01). After adjusting for other covariates, the presence of tic disorders was not associated with poor academic performance in our cohort. Early academic support and modification of environmental characteristics are needed for children at higher risk for school dysfunction, to enhance academic performance. Copyright © 2013 Mosby, Inc. All rights reserved.

Hysteroscopic sterilization success in outpatient vs office setting is not affected by patient or procedural characteristics.

PubMed

Anderson, Ted L; Yunker, Amanda C; Scheib, Stacey A; Callahan, Tamara L

2013-01-01

To determine factors associated with hysteroscopic sterilization success and whether it differs between the operating room and office settings. Retrospective cohort analysis (Canadian Task Force classification II-2). Major university medical center. Six hundred thirty-eight women who underwent hysteroscopic sterilization between July 1, 2005, and June 30, 2011. Data collected included age, body mass index, previous office procedures, previous cesarean section, and presence of myomas or retroverted uterus. Place of surgery, experience of surgeon, insurance type, bilateral device placement, compliance with hysterosalpingography, and confirmation of occlusion were also recorded. Bivariate analysis of patient characteristics between groups was performed using χ(2) and independent t tests, and identified confounders and associated variables. Multivariate analysis was performed using logistic regression to assess for association and to adjust for confounders. Procedures were performed in the operating room (57%) or in the office (43%). There was no association between success in bilateral device placement or occlusion and any patient characteristic, regardless of surgery setting. Private insurance, patient age, and performance of procedures in the office setting were positively associated with likelihood of compliance with hysterosalpingography. Successful device placement and tubal occlusion are independent of patient age, body mass index, or setting of the procedure. Association between insurance type and completing hysterosalpingography illustrates an important public health problem. Patients who fail to undergo hysterosalpingography to confirm tubal occlusion may unknowingly be at risk of pregnancy and increased risk of ectopic pregnancy. Copyright © 2013 AAGL. Published by Elsevier Inc. All rights reserved.

Depressive Symptoms and Salivary Telomere Length in a Probability Sample of Middle-Aged and Older Adults

PubMed Central

Whisman, Mark A.; Richardson, Emily D.

2016-01-01

Objective To examine the association between depressive symptoms and salivary telomere length in a probability sample of middle-aged and older adults, evaluate age and sex as potential moderators of this association, and test whether this association was incremental to potential confounds. Methods Participants were 3,609 individuals from the 2008 wave of the Health and Retirement Study. Telomere length assays were performed using quantitative real-time polymerase chain reaction (qPCR) on DNA extracted from saliva samples. Depressive symptoms were assessed via interview, and health and lifestyle factors, traumatic life events, and neuroticism were assessed via self-report. Regression analyses were conducted to examine the associations between predictor variables and salivary telomere length. Results After adjusting for demographics, depressive symptoms were negatively associated with salivary telomere length (b = −.003, p = .014). Furthermore, this association was moderated by sex (b = .005, p = .011), such that depressive symptoms were significantly and negatively associated with salivary telomere length for men (b = −.006, p < .001) but not for women (b = −.001, p = .644). The negative association between depressive symptoms and salivary telomere length in men remained statistically significant after additionally adjusting for cigarette smoking, body mass index, chronic health conditions, childhood and lifetime exposure to traumatic life events, and neuroticism. Conclusions Higher levels of depressive symptoms were associated with shorter salivary telomeres in men and this association was incremental to several potential confounds. Shortened telomeres may help account for the association between depression and poor physical health and mortality. PMID:28029664

A New Method for Partial Correction of Residual Confounding in Time-Series and Other Observational Studies.

PubMed

Flanders, W Dana; Strickland, Matthew J; Klein, Mitchel

2017-05-15

Methods exist to detect residual confounding in epidemiologic studies. One requires a negative control exposure with 2 key properties: 1) conditional independence of the negative control and the outcome (given modeled variables) absent confounding and other model misspecification, and 2) associations of the negative control with uncontrolled confounders and the outcome. We present a new method to partially correct for residual confounding: When confounding is present and our assumptions hold, we argue that estimators from models that include a negative control exposure with these 2 properties tend to be less biased than those from models without it. Using regression theory, we provide theoretical arguments that support our claims. In simulations, we empirically evaluated the approach using a time-series study of ozone effects on asthma emergency department visits. In simulations, effect estimators from models that included the negative control exposure (ozone concentrations 1 day after the emergency department visit) had slightly or modestly less residual confounding than those from models without it. Theory and simulations show that including the negative control can reduce residual confounding, if our assumptions hold. Our method differs from available methods because it uses a regression approach involving an exposure-based indicator rather than a negative control outcome to partially correct for confounding. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Refining adverse drug reaction signals by incorporating interaction variables identified using emergent pattern mining.

PubMed

Reps, Jenna M; Aickelin, Uwe; Hubbard, Richard B

2016-02-01

To develop a framework for identifying and incorporating candidate confounding interaction terms into a regularised cox regression analysis to refine adverse drug reaction signals obtained via longitudinal observational data. We considered six drug families that are commonly associated with myocardial infarction in observational healthcare data, but where the causal relationship ground truth is known (adverse drug reaction or not). We applied emergent pattern mining to find itemsets of drugs and medical events that are associated with the development of myocardial infarction. These are the candidate confounding interaction terms. We then implemented a cohort study design using regularised cox regression that incorporated and accounted for the candidate confounding interaction terms. The methodology was able to account for signals generated due to confounding and a cox regression with elastic net regularisation correctly ranking the drug families known to be true adverse drug reactions above those that are not. This was not the case without the inclusion of the candidate confounding interaction terms, where confounding leads to a non-adverse drug reaction being ranked highest. The methodology is efficient, can identify high-order confounding interactions and does not require expert input to specify outcome specific confounders, so it can be applied for any outcome of interest to quickly refine its signals. The proposed method shows excellent potential to overcome some forms of confounding and therefore reduce the false positive rate for signal analysis using longitudinal data. Copyright © 2015 Elsevier Ltd. All rights reserved.

Alzheimer disease genetic risk factor APOE e4 and cognitive abilities in 111,739 UK Biobank participants.

PubMed

Lyall, Donald M; Ward, Joey; Ritchie, Stuart J; Davies, Gail; Cullen, Breda; Celis, Carlos; Bailey, Mark E S; Anderson, Jana; Evans, Jon; Mckay, Daniel F; Mcintosh, Andrew M; Sattar, Naveed; Smith, Daniel J; Deary, Ian J; Pell, Jill P

2016-07-01

the apolipoprotein (APOE) e4 locus is a genetic risk factor for dementia. Carriers of the e4 allele may be more vulnerable to conditions that are independent risk factors for cognitive decline, such as cardiometabolic diseases. we tested whether any association with APOE e4 status on cognitive ability was larger in older ages or in those with cardiometabolic diseases. UK Biobank includes over 500,000 middle- and older aged adults who have undergone detailed medical and cognitive phenotypic assessment. Around 150,000 currently have genetic data. We examined 111,739 participants with complete genetic and cognitive data. baseline cognitive data relating to information processing speed, memory and reasoning were used. We tested for interactions with age and with the presence versus absence of type 2 diabetes (T2D), coronary artery disease (CAD) and hypertension. in several instances, APOE e4 dosage interacted with older age and disease presence to affect cognitive scores. When adjusted for potentially confounding variables, there was no APOE e4 effect on the outcome variables. future research in large independent cohorts should continue to investigate this important question, which has potential implications for aetiology related to dementia and cognitive impairment. © The Author 2016. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Relationships between Sleep Behaviors and Unintentional Injury in Southern Chinese School-Aged Children: A Population-Based Study.

PubMed

Tan, Yafei; Ma, Di; Chen, Ying; Cheng, Fuyuan; Liu, Xiangxiang; Li, Liping

2015-10-16

The purpose of this study is to explore the relationships between sleep behaviors and injury occurrence among Chinese school-aged children. Data were collected with self-administered questionnaires of a cross-sectional survey which covered the school-aged children from southeastern Chinese urban and rural areas in April 2010. Information was collected on unintentional injury in the past year, sleep duration, napping and daytime fatigue, sleeping pill use, and social-demographic variables. Multivariable logistic regression analyses, controlling for confounding factors, were conducted to assess sleep-related variables that were associated with injuries. Students who slept for less than 8 h had a 30% increased risk of injury (OR: 1.30; 95%CI: 1.01-1.69) compared with those who slept for 8-9 h. Lack of napping, snoring and use of sleeping pills were significantly associated with injury. Among different genders, the slight difference in sleep behaviors predicted the occurrence of injury. Rural children displayed more sleep behaviors associated with injury than urban children. The sleep behaviors of primary school students were more negatively correlated with injury occurrence than junior/senior high school children. Consideration should be given to the prevention of problematic sleep behaviors as a potential risk factor in order to decrease injury rates and promote the health of school-aged children.

Relationships between Sleep Behaviors and Unintentional Injury in Southern Chinese School-Aged Children: A Population-Based Study

PubMed Central

Tan, Yafei; Ma, Di; Chen, Ying; Cheng, Fuyuan; Liu, Xiangxiang; Li, Liping

2015-01-01

The purpose of this study is to explore the relationships between sleep behaviors and injury occurrence among Chinese school-aged children. Data were collected with self-administered questionnaires of a cross-sectional survey which covered the school-aged children from southeastern Chinese urban and rural areas in April 2010. Information was collected on unintentional injury in the past year, sleep duration, napping and daytime fatigue, sleeping pill use, and social-demographic variables. Multivariable logistic regression analyses, controlling for confounding factors, were conducted to assess sleep-related variables that were associated with injuries. Students who slept for less than 8 h had a 30% increased risk of injury (OR: 1.30; 95%CI: 1.01–1.69) compared with those who slept for 8–9 h. Lack of napping, snoring and use of sleeping pills were significantly associated with injury. Among different genders, the slight difference in sleep behaviors predicted the occurrence of injury. Rural children displayed more sleep behaviors associated with injury than urban children. The sleep behaviors of primary school students were more negatively correlated with injury occurrence than junior/senior high school children. Consideration should be given to the prevention of problematic sleep behaviors as a potential risk factor in order to decrease injury rates and promote the health of school-aged children. PMID:26501305

Indexing the relative abundance of age-0 white sturgeons in an impoundment of the lower Columbia River from highly skewed trawling data

USGS Publications Warehouse

Counihan, T.D.; Miller, Allen I.; Parsley, M.J.

1999-01-01

The development of recruitment monitoring programs for age-0 white sturgeons Acipenser transmontanus is complicated by the statistical properties of catch-per-unit-effort (CPUE) data. We found that age-0 CPUE distributions from bottom trawl surveys violated assumptions of statistical procedures based on normal probability theory. Further, no single data transformation uniformly satisfied these assumptions because CPUE distribution properties varied with the sample mean (??(CPUE)). Given these analytic problems, we propose that an additional index of age-0 white sturgeon relative abundance, the proportion of positive tows (Ep), be used to estimate sample sizes before conducting age-0 recruitment surveys and to evaluate statistical hypothesis tests comparing the relative abundance of age-0 white sturgeons among years. Monte Carlo simulations indicated that Ep was consistently more precise than ??(CPUE), and because Ep is binomially rather than normally distributed, surveys can be planned and analyzed without violating the assumptions of procedures based on normal probability theory. However, we show that Ep may underestimate changes in relative abundance at high levels and confound our ability to quantify responses to management actions if relative abundance is consistently high. If data suggest that most samples will contain age-0 white sturgeons, estimators of relative abundance other than Ep should be considered. Because Ep may also obscure correlations to climatic and hydrologic variables if high abundance levels are present in time series data, we recommend ??(CPUE) be used to describe relations to environmental variables. The use of both Ep and ??(CPUE) will facilitate the evaluation of hypothesis tests comparing relative abundance levels and correlations to variables affecting age-0 recruitment. Estimated sample sizes for surveys should therefore be based on detecting predetermined differences in Ep, but data necessary to calculate ??(CPUE) should also be collected.

Exclusive breastfeeding and other foods in the first six months of life: effects on nutritional status and body composition of Brazilian children.

PubMed

Magalhães, Taís C A; Vieira, Sarah A; Priore, Silvia E; Ribeiro, Andréia Q; Lamounier, Joel A; Franceschini, Sylvia C C; Sant'Ana, Luciana F R

2012-01-01

To evaluate the effect of exclusive breastfeeding and consumption of other foods in the first six months of life in the nutritional status and body composition of children. A retrospective cohort study with 185 children aged from 4 to 7 years was monitored during the first months of life in a program of support to breastfeeding. We evaluated weight, height, waist circumference, and body composition by using DEXA. The nutritional status was assessed by the BMI/age index. The parameters of adiposity were classified by using as the cutoff point, the 85th percentile of the sample itself, according to gender and age. Confounding factors considered were variables related to maternal, pregnancy, birth, sociodemographic, health, lifestyle, and diet. Bivariate and multivariate analyses were performed, the latter by means of multiple logistic regression. The median exclusive breastfeeding was 3 months. Of the children, 42.7% received cow's milk and 35.7% received infant formula. Regarding nutritional status, 21.1% of the children showed changes. The variables of infant feeding were not independently associated with nutritional status and body composition of the children and there were no differences between the groups studied. Breastfeeding was not a protective factor to overweight and body fat in children.

Does gender modify associations between self rated health and the social and economic characteristics of local environments?

PubMed

Kavanagh, Anne M; Bentley, Rebecca; Turrell, Gavin; Broom, Dorothy H; Subramanian, S V

2006-06-01

To examine whether area level socioeconomic disadvantage and social capital have different relations with women's and men's self rated health. The study used data from 15 112 respondents to the 1998 Tasmanian (Australia) healthy communities study (60% response rate) nested within 41 statistical local areas. Gender stratified analyses were conducted of the associations between the index of relative socioeconomic disadvantage (IRSD) and social capital (neighbourhood integration, neighbourhood alienation, neighbourhood safety, political participation, social trust, trust in institutions) and individual level self rated health using multilevel logistic regression analysis before (age only) and after adjustment for individual level confounders (marital status, indigenous status, income, education, occupation, smoking). The study also tested for interactions between gender and area level variables. IRSD was associated with poor self rated health for women (age adjusted p<0.001) and men (age adjusted p<0.001), however, the estimates attenuated when adjusted for individual level variables. Political participation and neighbourhood safety were protective for women's self rated health but not for men's. Interactions between gender and political participation (p = 0.010) and neighbourhood safety (p = 0.023) were significant. These finding suggest that women may benefit more than men from higher levels of area social capital.

Environmental Factors Associated With Social Participation of Older Adults Living in Metropolitan, Urban, and Rural Areas: The NuAge Study

PubMed Central

Cohen, Alan A.; Dubois, Marie-France; Généreux, Mélissa; Richard, Lucie; Therrien, France-Hélène; Payette, Hélène

2015-01-01

Objectives. We compared the social participation of older adults living in metropolitan, urban, and rural areas, and identified associated environmental factors. Methods. From 2004 to 2006, we conducted a cross-sectional study using an age-, gender-, and area-stratified random sample of 1198 adults (aged 67–82 years). We collected data via interviewer-administered questionnaires and derived from Canadian censuses. Results. Social participation did not differ across living areas (P = .09), but after controlling for potential confounding variables, we identified associated area-specific environmental variables. In metropolitan areas, higher social participation was associated with greater proximity to neighborhood resources, having a driver’s license, transit use, and better quality social network (R2 = 0.18). In urban areas, higher social participation was associated with greater proximity to neighborhood resources and having a driver’s license (R2 = 0.11). Finally, in rural areas, higher social participation was associated with greater accessibility to key resources, having a driver’s license, children living in the neighborhood, and more years lived in the current dwelling (R2 = 0.18). Conclusions. To enhance social participation of older adults, public health interventions need to address different environmental factors according to living areas. PMID:25689194

Exclusive Breastfeeding and Other Foods in the First Six Months of Life: Effects on Nutritional Status and Body Composition of Brazilian Children

PubMed Central

Magalhães, Taís C. A.; Vieira, Sarah A.; Priore, Silvia E.; Ribeiro, Andréia Q.; Lamounier, Joel A.; Franceschini, Sylvia C. C.; Sant'Ana, Luciana F. R.

2012-01-01

Objective. To evaluate the effect of exclusive breastfeeding and consumption of other foods in the first six months of life in the nutritional status and body composition of children. Methods. A retrospective cohort study with 185 children aged from 4 to 7 years was monitored during the first months of life in a program of support to breastfeeding. We evaluated weight, height, waist circumference, and body composition by using DEXA. The nutritional status was assessed by the BMI/age index. The parameters of adiposity were classified by using as the cutoff point, the 85th percentile of the sample itself, according to gender and age. Confounding factors considered were variables related to maternal, pregnancy, birth, sociodemographic, health, lifestyle, and diet. Bivariate and multivariate analyses were performed, the latter by means of multiple logistic regression. Results. The median exclusive breastfeeding was 3 months. Of the children, 42.7% received cow's milk and 35.7% received infant formula. Regarding nutritional status, 21.1% of the children showed changes. The variables of infant feeding were not independently associated with nutritional status and body composition of the children and there were no differences between the groups studied. Conclusion. Breastfeeding was not a protective factor to overweight and body fat in children. PMID:23193378

The obesity paradox in stable chronic heart failure does not persist after matching for indicators of disease severity and confounders.

PubMed

Frankenstein, Lutz; Zugck, Christian; Nelles, Manfred; Schellberg, Dieter; Katus, Hugo A; Remppis, B Andrew

2009-12-01

To verify whether controlling for indicators of disease severity and confounders represents a solution to the obesity paradox in chronic heart failure (CHF). From a cohort of 1790 patients, we formed 230 nested matched triplets by individually matching patients with body mass index (BMI) > 30 kg/m(2) (Group 3), BMI 20-24.9 k/m(2) (Group 1) and BMI 25-29.9 kg/m(2) (Group 2), according to NT-proBNP, age, sex, and NYHA class (triplet = one matched patient from each group). Although in the pre-matching cohort, BMI group was a significant univariable prognostic indicator, it did not retain significance [heart rate (HR): 0.91, 95% CI: 0.78-1.05, chi(2): 1.67] when controlled for group propensities as covariates. Furthermore, in the matched cohort, 1-year mortality and 3-year mortality did not differ significantly. Here, BMI again failed to reach statistical significance for prognosis, either as a continuous or categorical variable, whether crude or adjusted. This result was confirmed in the patients not selected for matching. NT-proBNP, however, remained statistically significant (log(NT-proBNP): HR: 1.49, 95% CI: 1.13-1.97, chi(2): 7.82) after multivariable adjustment. The obesity paradox does not appear to persist in a matched setting with respect to indicators of disease severity and other confounders. NT-proBNP remains an independent prognostic indicator of adverse outcome irrespective of obesity status.

Environmental confounding in gene-environment interaction studies.

PubMed

Vanderweele, Tyler J; Ko, Yi-An; Mukherjee, Bhramar

2013-07-01

We show that, in the presence of uncontrolled environmental confounding, joint tests for the presence of a main genetic effect and gene-environment interaction will be biased if the genetic and environmental factors are correlated, even if there is no effect of either the genetic factor or the environmental factor on the disease. When environmental confounding is ignored, such tests will in fact reject the joint null of no genetic effect with a probability that tends to 1 as the sample size increases. This problem with the joint test vanishes under gene-environment independence, but it still persists if estimating the gene-environment interaction parameter itself is of interest. Uncontrolled environmental confounding will bias estimates of gene-environment interaction parameters even under gene-environment independence, but it will not do so if the unmeasured confounding variable itself does not interact with the genetic factor. Under gene-environment independence, if the interaction parameter without controlling for the environmental confounder is nonzero, then there is gene-environment interaction either between the genetic factor and the environmental factor of interest or between the genetic factor and the unmeasured environmental confounder. We evaluate several recently proposed joint tests in a simulation study and discuss the implications of these results for the conduct of gene-environment interaction studies.

Negative control exposure studies in the presence of measurement error: implications for attempted effect estimate calibration

PubMed Central

Sanderson, Eleanor; Macdonald-Wallis, Corrie; Davey Smith, George

2018-01-01

Abstract Background Negative control exposure studies are increasingly being used in epidemiological studies to strengthen causal inference regarding an exposure-outcome association when unobserved confounding is thought to be present. Negative control exposure studies contrast the magnitude of association of the negative control, which has no causal effect on the outcome but is associated with the unmeasured confounders in the same way as the exposure, with the magnitude of the association of the exposure with the outcome. A markedly larger effect of the exposure on the outcome than the negative control on the outcome strengthens inference that the exposure has a causal effect on the outcome. Methods We investigate the effect of measurement error in the exposure and negative control variables on the results obtained from a negative control exposure study. We do this in models with continuous and binary exposure and negative control variables using analysis of the bias of the estimated coefficients and Monte Carlo simulations. Results Our results show that measurement error in either the exposure or negative control variables can bias the estimated results from the negative control exposure study. Conclusions Measurement error is common in the variables used in epidemiological studies; these results show that negative control exposure studies cannot be used to precisely determine the size of the effect of the exposure variable, or adequately adjust for unobserved confounding; however, they can be used as part of a body of evidence to aid inference as to whether a causal effect of the exposure on the outcome is present. PMID:29088358

Negative control exposure studies in the presence of measurement error: implications for attempted effect estimate calibration.

PubMed

Sanderson, Eleanor; Macdonald-Wallis, Corrie; Davey Smith, George

2018-04-01

Negative control exposure studies are increasingly being used in epidemiological studies to strengthen causal inference regarding an exposure-outcome association when unobserved confounding is thought to be present. Negative control exposure studies contrast the magnitude of association of the negative control, which has no causal effect on the outcome but is associated with the unmeasured confounders in the same way as the exposure, with the magnitude of the association of the exposure with the outcome. A markedly larger effect of the exposure on the outcome than the negative control on the outcome strengthens inference that the exposure has a causal effect on the outcome. We investigate the effect of measurement error in the exposure and negative control variables on the results obtained from a negative control exposure study. We do this in models with continuous and binary exposure and negative control variables using analysis of the bias of the estimated coefficients and Monte Carlo simulations. Our results show that measurement error in either the exposure or negative control variables can bias the estimated results from the negative control exposure study. Measurement error is common in the variables used in epidemiological studies; these results show that negative control exposure studies cannot be used to precisely determine the size of the effect of the exposure variable, or adequately adjust for unobserved confounding; however, they can be used as part of a body of evidence to aid inference as to whether a causal effect of the exposure on the outcome is present.

Gender effects in gaming research: a case for regression residuals?

PubMed

Pfister, Roland

2011-10-01

Numerous recent studies have examined the impact of video gaming on various dependent variables, including the players' affective reactions, positive as well as detrimental cognitive effects, and real-world aggression. These target variables are typically analyzed as a function of game characteristics and player attributes-especially gender. However, findings on the uneven distribution of gaming experience between males and females, on the one hand, and the effect of gaming experience on several target variables, on the other hand, point at a possible confound when gaming experiments are analyzed with a standard analysis of variance. This study uses simulated data to exemplify analysis of regression residuals as a potentially beneficial data analysis strategy for such datasets. As the actual impact of gaming experience on each of the various dependent variables differs, the ultimate benefits of analysis of regression residuals entirely depend on the research question, but it offers a powerful statistical approach to video game research whenever gaming experience is a confounding factor.

[A follow-up study of the elderly in agricultural and piscatorial areas of Hokkaido].

PubMed

Mori, M; Goto, R; Masuoka, H; Yoshida, K; Miyake, H

1990-02-01

A base-line survey was performed for 3,185 persons over 40 years of age in 1984 and 1985 in agricultural and piscatorial areas of Hokkaido with regards to their dietary habits and life style. Of them, 147 persons died prior to the recent follow-up survey of 1988. As a result of a case-control study of the dead with those of the followed-up group, a more frequent intake of instant noodles was indicated as significantly increasing the risk of death, even after adjusting for the health status at the base-line survey and other confounding variables (the adjusted relative risk = 1.44 per a frequency class, p = 0.049).

Resveratrol supplementation: Where are we now and where should we go?

PubMed

Novelle, Marta G; Wahl, Devin; Diéguez, Carlos; Bernier, Michel; de Cabo, Rafael

2015-05-01

Pre-clinical findings have provided mounting evidence that resveratrol, a dietary polyphenol, may confer health benefits and protect against a variety of medical conditions and age-related complications. However, there is no consistent evidence of an increased protection against metabolic disorders and other ailments when comparing studies in laboratory animals and humans. A number of extraneous and potential confounding variables can affect the outcome of clinical research. To date, most of the studies that have investigated the effect of resveratrol administration on patient outcomes have been limited by their sample sizes. In this review, we will survey the latest advances regarding the timing, dosage, formulation, bioavailability, toxicity of resveratrol, and resveratrol-drug interactions in human studies. Moreover, the present report focuses on the actions of resveratrol treatment in combating diseases, such as cancer, diabetes, neurodegeneration, cardiovascular disease, and other age-related ailments. Published by Elsevier B.V.

Resveratrol supplementation, where are we now and where should we go?

PubMed Central

Novelle, Marta G.; Wahl, Devin; Dieguez, Carlos; Bernier, Michel; de Cabo, Rafael

2018-01-01

Pre-clinical findings have provided mounting evidence that resveratrol, a dietary polyphenol, may confer health benefits and protect against a variety of medical conditions and age-related complications. However, there is no consistent evidence of an increased protection against metabolic disorders and other ailments when comparing studies in laboratory animals and humans. A number of extraneous and potential confounding variables can affect the outcome of clinical research. To date, most of the studies that have investigated the effect of resveratrol administration on patient outcomes have been limited by their sample sizes. In this review we will survey the latest advances regarding the timing, dosage, formulation, bioavailability, and toxicity of resveratrol, and resveratrol-drug interactions in human studies. Moreover, the present report focuses on the actions of resveratrol treatment in combatting diseases, such as cancer, diabetes, neurodegeneration, cardiovascular disease, and other age-related ailments. PMID:25625901

Phonological Awareness, Reading Skills, and Vocabulary Knowledge in Children Who Use Cochlear Implants

PubMed Central

Dillon, Caitlin M.; de Jong, Kenneth; Pisoni, David B.

2012-01-01

In hearing children, reading skills have been found to be closely related to phonological awareness. We used several standardized tests to investigate the reading and phonological awareness skills of 27 deaf school-age children who were experienced cochlear implant users. Approximately two-thirds of the children performed at or above the level of their hearing peers on the phonological awareness and reading tasks. Reading scores were found to be strongly correlated with measures of phonological awareness. These correlations remained the same when we statistically controlled for potentially confounding demographic variables such as age at testing and speech perception skills. However, these correlations decreased even after we statistically controlled for vocabulary size. This finding suggests that lexicon size is a mediating factor in the relationship between the children’s phonological awareness and reading skills, a finding that has also been reported for typically developing hearing children. PMID:22057983

Insulin-Like Growth Factor 1 (IGF-1) in Parkinson's Disease: Potential as Trait-, Progression- and Prediction Marker and Confounding Factors.

PubMed

Bernhard, Felix P; Heinzel, Sebastian; Binder, Gerhard; Weber, Karin; Apel, Anja; Roeben, Benjamin; Deuschle, Christian; Maechtel, Mirjam; Heger, Tanja; Nussbaum, Susanne; Gasser, Thomas; Maetzler, Walter; Berg, Daniela

2016-01-01

Biomarkers indicating trait, progression and prediction of pathology and symptoms in Parkinson's disease (PD) often lack specificity or reliability. Investigating biomarker variance between individuals and over time and the effect of confounding factors is essential for the evaluation of biomarkers in PD, such as insulin-like growth factor 1 (IGF-1). IGF-1 serum levels were investigated in up to 8 biannual visits in 37 PD patients and 22 healthy controls (HC) in the longitudinal MODEP study. IGF-1 baseline levels and annual changes in IGF-1 were compared between PD patients and HC while accounting for baseline disease duration (19 early stage: ≤3.5 years; 18 moderate stage: >4 years), age, sex, body mass index (BMI) and common medical factors putatively modulating IGF-1. In addition, associations of baseline IGF-1 with annual changes of motor, cognitive and depressive symptoms and medication dose were investigated. PD patients in moderate (130±26 ng/mL; p = .004), but not early stages (115±19, p>.1), showed significantly increased baseline IGF-1 levels compared with HC (106±24 ng/mL; p = .017). Age had a significant negative correlation with IGF-1 levels in HC (r = -.47, p = .028) and no correlation in PD patients (r = -.06, p>.1). BMI was negatively correlated in the overall group (r = -.28, p = .034). The annual changes in IGF-1 did not differ significantly between groups and were not correlated with disease duration. Baseline IGF-1 levels were not associated with annual changes of clinical parameters. Elevated IGF-1 in serum might differentiate between patients in moderate PD stages and HC. However, the value of serum IGF-1 as a trait-, progression- and prediction marker in PD is limited as IGF-1 showed large inter- and intraindividual variability and may be modulated by several confounders.

Insulin-Like Growth Factor 1 (IGF-1) in Parkinson's Disease: Potential as Trait-, Progression- and Prediction Marker and Confounding Factors

PubMed Central

Binder, Gerhard; Weber, Karin; Apel, Anja; Roeben, Benjamin; Deuschle, Christian; Maechtel, Mirjam; Heger, Tanja; Nussbaum, Susanne; Gasser, Thomas; Maetzler, Walter; Berg, Daniela

2016-01-01

Introduction Biomarkers indicating trait, progression and prediction of pathology and symptoms in Parkinson's disease (PD) often lack specificity or reliability. Investigating biomarker variance between individuals and over time and the effect of confounding factors is essential for the evaluation of biomarkers in PD, such as insulin-like growth factor 1 (IGF-1). Materials and Methods IGF-1 serum levels were investigated in up to 8 biannual visits in 37 PD patients and 22 healthy controls (HC) in the longitudinal MODEP study. IGF-1 baseline levels and annual changes in IGF-1 were compared between PD patients and HC while accounting for baseline disease duration (19 early stage: ≤3.5 years; 18 moderate stage: >4 years), age, sex, body mass index (BMI) and common medical factors putatively modulating IGF-1. In addition, associations of baseline IGF-1 with annual changes of motor, cognitive and depressive symptoms and medication dose were investigated. Results PD patients in moderate (130±26 ng/mL; p = .004), but not early stages (115±19, p>.1), showed significantly increased baseline IGF-1 levels compared with HC (106±24 ng/mL; p = .017). Age had a significant negative correlation with IGF-1 levels in HC (r = -.47, p = .028) and no correlation in PD patients (r = -.06, p>.1). BMI was negatively correlated in the overall group (r = -.28, p = .034). The annual changes in IGF-1 did not differ significantly between groups and were not correlated with disease duration. Baseline IGF-1 levels were not associated with annual changes of clinical parameters. Discussion Elevated IGF-1 in serum might differentiate between patients in moderate PD stages and HC. However, the value of serum IGF-1 as a trait-, progression- and prediction marker in PD is limited as IGF-1 showed large inter- and intraindividual variability and may be modulated by several confounders. PMID:26967642

Abdominal obesity and its association with socioeconomic factors among adolescents from different living environments.

PubMed

Costa de Oliveira Forkert, E; de Moraes, A C F; Carvalho, H B; Kafatos, A; Manios, Y; Sjöström, M; González-Gross, M; Gottrand, F; Beghin, L; Censi, L; Kersting, M; Moreno, L A

2017-04-01

Socioeconomic status has been associated with obesity in children and adolescents. This association may be dependent according with where adolescents lives. The aim of this study was to evaluate the association between different socioeconomic indicators such as parental education and occupation and socioeconomic status with abdominal obesity in adolescents from two observational studies: the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study (HELENA-CSS) and the Brazilian Cardiovascular Adolescent Health (BRACAH) study. European (n = 3192, aged 12.5-17.5 years, with 53.1% girls from HELENA-CSS) and Brazilian (n = 991, aged 14-18 years, with 54.5% girls from BRACAH study) adolescents from two cross-sectional studies were included in this analysis. Complete data on waist circumference (WC), height, socioeconomic status indicators and several confounders were collected. Socioeconomic indicators were measured using a self-reported questionnaire in order to assess the family social status of the adolescents. Multilevel linear regression models were used to examine associations, and results were adjusted for potential confounders. Adjusted results showed inverse associations between mother's and father's education levels (p < 0.001) and father's occupation level (p < 0.001) with waist-to-height ratio (WHtR) and WC in HELENA-CSS girls. Similarly in European girls, socioeconomic indicators by socioeconomic status and maternal occupation level were associated with WHtR. In HELENA-CSS boys, the same significant association was found between WHtR and WC with maternal occupation level. Moreover, in European boys WHtR was also associated with parental education. In Brazilian adolescents, both indicators of abdominal obesity did not remain associated with the independents variables, after adjustment for potential confounders. Abdominal obesity was associated with socioeconomic indicators in higher-income countries, but this association was not observed in a lower-middle-income country. © 2016 World Obesity Federation.

The impact of alcohol marketing on youth drinking behaviour: a two-stage cohort study.

PubMed

Gordon, Ross; MacKintosh, Anne Marie; Moodie, Crawford

2010-01-01

To examine whether awareness of, and involvement with alcohol marketing at age 13 is predictive of initiation of drinking, frequency of drinking and units of alcohol consumed at age 15. A two-stage cohort study, involving a questionnaire survey, combining interview and self-completion, was administered in respondents' homes. Respondents were drawn from secondary schools in three adjoining local authority areas in the West of Scotland, UK. From a baseline sample of 920 teenagers (aged 12-14, mean age 13), in 2006, a cohort of 552 was followed up 2 years later (aged 14-16, mean age 15). Data were gathered on multiple forms of alcohol marketing and measures of drinking initiation, frequency and consumption. At follow-up, logistic regression demonstrated that, after controlling for confounding variables, involvement with alcohol marketing at baseline was predictive of both uptake of drinking and increased frequency of drinking. Awareness of marketing at baseline was also associated with an increased frequency of drinking at follow-up. Our findings demonstrate an association between involvement with, and awareness of, alcohol marketing and drinking uptake or increased drinking frequency, and we consider whether the current regulatory environment affords youth sufficient protection from alcohol marketing.

Air pollution and heart rate variability: effect modification by chronic lead exposure.

PubMed

Park, Sung Kyun; O'Neill, Marie S; Vokonas, Pantel S; Sparrow, David; Wright, Robert O; Coull, Brent; Nie, Huiling; Hu, Howard; Schwartz, Joel

2008-01-01

Outdoor air pollution and lead exposure can disturb cardiac autonomic function, but the effects of both these exposures together have not been studied. We examined whether higher cumulative lead exposures, as measured by bone lead, modified cross-sectional associations between air pollution and heart rate variability among 384 elderly men from the Normative Aging Study. We used linear regression, controlling for clinical, demographic, and environmental covariates. We found graded, significant reductions in both high-frequency and low-frequency powers of heart rate variability in relation to ozone and sulfate across the quartiles of tibia lead. Interquartile range increases in ozone and sulfate were associated respectively, with 38% decrease (95% confidence interval = -54.6% to -14.9%) and 22% decrease (-40.4% to 1.6%) in high frequency, and 38% decrease (-51.9% to -20.4%) and 12% decrease (-28.6% to 9.3%) in low frequency, in the highest quartile of tibia lead after controlling for potential confounders. We observed similar but weaker effect modification by tibia lead adjusted for education and cumulative traffic (residuals of the regression of tibia lead on education and cumulative traffic). Patella lead modified only the ozone effect on heart rate variability. People with long-term exposure to higher levels of lead may be more sensitive to cardiac autonomic dysfunction on high air pollution days. Efforts to understand how environmental exposures affect the health of an aging population should consider both current levels of pollution and history of lead exposure as susceptibility factors.

Fatigue and crashes: the case of freight transport in Colombia.

PubMed

Torregroza-Vargas, Nathaly M; Bocarejo, Juan Pablo; Ramos-Bonilla, Juan P

2014-11-01

Truck drivers have been involved in a significant number of road fatalities in Colombia. To identify variables that could be associated with crashes in which truck drivers are involved, a logistic regression model was constructed. The model had as the response variable a dichotomous variable that included the presence or absence of a crash during a specific trip. As independent variables the model included information regarding a driver's work shift, with variables that could be associated with driver's fatigue. The model also included potential confounders related with road conditions. With the model, it was possible to determine the odds ratio of a crash in relation to several variables, adjusting for confounding. To collect the information about the trips included in the model, a survey among truck drivers was conducted. The results suggest strong associations between crashes (i.e., some of them statistically significant) with the number of stops made during the trip, and the average time of each stop. Survey analysis allowed us to identify the practices that contribute to generating fatigue and unhealthy conditions on the road among professional drivers. A review of national regulations confirmed the lack of legislation on this topic. Copyright © 2014 Elsevier Ltd. All rights reserved.

Do Gender-Predominant Primary Health Care Organizations Have an Impact on Patient Experience of Care, Use of Services, and Unmet Needs?

PubMed

Pineault, Raynald; Borgès Da Silva, Roxane; Provost, Sylvie; Fournier, Michel; Prud'homme, Alexandre; Levesque, Jean-Frédéric

2017-01-01

Physicians' gender can have an impact on many aspects of patient experience of care. Organization processes through which the influence of gender is exerted have not been fully explored. The aim of this article is to compare primary health care (PHC) organizations in which female or male doctors are predominant regarding organization and patient characteristics, and to assess their influence on experience of care, preventive care delivery, use of services, and unmet needs. In 2010, we conducted surveys of a population stratified sample (N = 9180) and of all PHC organizations (N = 606) in 2 regions of the province of Québec, Canada. Patient and organization variables were entered sequentially into multilevel regression analyses to measure the impact of gender predominance. Female-predominant organizations had younger doctors and nurses with more expanded role; they collaborated more with other PHC practices, used more tools for prevention, and allotted more time to patient visits. However, doctors spent fewer hours a week at the practice in female-predominant organizations. Patients of these organizations reported lower accessibility. Conversely, they reported better comprehensiveness, responsiveness, counseling, and screening, but these effects were mainly attributable to doctors' younger age. Their reporting unmet needs and emergency department attendance tended to decrease when controlling for patient and organization variables other than doctors' age. Except for accessibility, female-predominant PHC organizations are comparable with their male counterparts. Mean age of doctors was an important confounding variable that mitigated differences, whereas other organization variables enhanced them. These findings deserve consideration to better understand and assess the impacts of the growing number of female-predominant PHC organizations on the health care system.

Do Gender-Predominant Primary Health Care Organizations Have an Impact on Patient Experience of Care, Use of Services, and Unmet Needs?

PubMed Central

Pineault, Raynald; Borgès Da Silva, Roxane; Provost, Sylvie; Fournier, Michel; Prud’homme, Alexandre; Levesque, Jean-Frédéric

2017-01-01

Physicians’ gender can have an impact on many aspects of patient experience of care. Organization processes through which the influence of gender is exerted have not been fully explored. The aim of this article is to compare primary health care (PHC) organizations in which female or male doctors are predominant regarding organization and patient characteristics, and to assess their influence on experience of care, preventive care delivery, use of services, and unmet needs. In 2010, we conducted surveys of a population stratified sample (N = 9180) and of all PHC organizations (N = 606) in 2 regions of the province of Québec, Canada. Patient and organization variables were entered sequentially into multilevel regression analyses to measure the impact of gender predominance. Female-predominant organizations had younger doctors and nurses with more expanded role; they collaborated more with other PHC practices, used more tools for prevention, and allotted more time to patient visits. However, doctors spent fewer hours a week at the practice in female-predominant organizations. Patients of these organizations reported lower accessibility. Conversely, they reported better comprehensiveness, responsiveness, counseling, and screening, but these effects were mainly attributable to doctors’ younger age. Their reporting unmet needs and emergency department attendance tended to decrease when controlling for patient and organization variables other than doctors’ age. Except for accessibility, female-predominant PHC organizations are comparable with their male counterparts. Mean age of doctors was an important confounding variable that mitigated differences, whereas other organization variables enhanced them. These findings deserve consideration to better understand and assess the impacts of the growing number of female-predominant PHC organizations on the health care system. PMID:28578608

Efficient estimation of the attributable fraction when there are monotonicity constraints and interactions.

PubMed

Traskin, Mikhail; Wang, Wei; Ten Have, Thomas R; Small, Dylan S

2013-01-01

The PAF for an exposure is the fraction of disease cases in a population that can be attributed to that exposure. One method of estimating the PAF involves estimating the probability of having the disease given the exposure and confounding variables. In many settings, the exposure will interact with the confounders and the confounders will interact with each other. Also, in many settings, the probability of having the disease is thought, based on subject matter knowledge, to be a monotone increasing function of the exposure and possibly of some of the confounders. We develop an efficient approach for estimating logistic regression models with interactions and monotonicity constraints, and apply this approach to estimating the population attributable fraction (PAF). Our approach produces substantially more accurate estimates of the PAF in some settings than the usual approach which uses logistic regression without monotonicity constraints.

Cognitive function in childhood and lifetime cognitive change in relation to mental wellbeing in four cohorts of older people.

PubMed

Gale, Catharine R; Cooper, Rachel; Craig, Leone; Elliott, Jane; Kuh, Diana; Richards, Marcus; Starr, John M; Whalley, Lawrence J; Deary, Ian J

2012-01-01

Poorer cognitive ability in youth is a risk factor for later mental health problems but it is largely unknown whether cognitive ability, in youth or in later life, is predictive of mental wellbeing. The purpose of this study was to investigate whether cognitive ability at age 11 years, cognitive ability in later life, or lifetime cognitive change are associated with mental wellbeing in older people. We used data on 8191 men and women aged 50 to 87 years from four cohorts in the HALCyon collaborative research programme into healthy ageing: the Aberdeen Birth Cohort 1936, the Lothian Birth Cohort 1921, the National Child Development Survey, and the MRC National Survey for Health and Development. We used linear regression to examine associations between cognitive ability at age 11, cognitive ability in later life, and lifetime change in cognitive ability and mean score on the Warwick Edinburgh Mental Wellbeing Scale and meta-analysis to obtain an overall estimate of the effect of each. People whose cognitive ability at age 11 was a standard deviation above the mean scored 0.53 points higher on the mental wellbeing scale (95% confidence interval 0.36, 0.71). The equivalent value for cognitive ability in later life was 0.89 points (0.72, 1.07). A standard deviation improvement in cognitive ability in later life relative to childhood ability was associated with 0.66 points (0.39, 0.93) advantage in wellbeing score. These effect sizes equate to around 0.1 of a standard deviation in mental wellbeing score. Adjustment for potential confounding and mediating variables, primarily the personality trait neuroticism, substantially attenuated these associations. Associations between cognitive ability in childhood or lifetime cognitive change and mental wellbeing in older people are slight and may be confounded by personality trait differences.

Youth unemployment and functional somatic symptoms in adulthood: results from the Northern Swedish cohort.

PubMed

Brydsten, Anna; Hammarström, Anne; Strandh, Mattias; Johansson, Klara

2015-10-01

Little is known about the possible long-term health consequences of youth unemployment. Research indicates that unemployment may lead to socioeconomic downward mobility and mental health problems, but we still lack knowledge of the long-term health consequences of youth unemployment. This article examines the potential long-term association between youth unemployment and functional somatic symptoms in adulthood. The 'Northern Swedish cohort' was used with data from five data collections, from 1981 (age 16) until 2007 (age 42). Youth unemployment was measured as months in unemployment between age 16 and 21, and health outcome as functional somatic symptoms (an index of 10 items of self-reported symptoms). Linear regression was used to analyse the relationship between months in youth unemployment and functional somatic symptoms at age 21 and age 42, stratified for women and men and adjusted for potential confounders, such as time spent in education at age 21 and later unemployment between age 21 and 42. Youth unemployment was significantly related to functional somatic symptoms at age 21 for men after controlling for confounders, but not for women. Among men, the association remained for functional somatic symptoms at age 42, after controlling for confounders. Adolescence seems to be a sensitive period during which unemployment could have remaining health effects in adulthood, at least for men, though assumptions of causality are tentative and more research is needed. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Predicting Perceived Isolation among Midlife and Older LGBT Adults: The Role of Welcoming Aging Service Providers.

PubMed

Yang, Jie; Chu, Yoosun; Salmon, Mary Anne

2017-06-16

Older lesbian, gay, bisexual, and transgender (LGBT) adults are more likely to live alone and less likely to have children compared with their heterosexual counterparts. The lack of immediate family system can render older LGBT adults particularly vulnerable to social isolation and its consequences. The current study utilizes social exclusion theory, which asserts that not only material resources but also engagement with and inclusion into the society are necessary for marginalized people to be integrated into the mainstream. The study examines whether aging service providers (e.g., senior centers, adult day care, transportation, employment services) who are perceived by older LGBT adults as welcoming to LGBT people may reduce this population's perceived isolation. Data were collected through a needs assessment survey designed for the aging LGBT community in North Carolina. Adults aged 45 and over who self-identified as LGBT were recruited at several formal and informal groups. The survey yielded 222 valid responses. The outcome variable was perceived isolation. Key independent variables included having experienced welcoming aging service providers and living alone. After controlling for potential confounders and demographics, logistic regression results showed that having experienced welcoming aging service providers was a protective factor against perceived isolation and it also buffered the negative impact of living alone. The findings provided preliminary evidence for a new direction of intervention research-targeting LGBT cultural competence training for medical and social service providers. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Housing conditions and mental health in a disadvantaged area in Scotland.

PubMed Central

Hopton, J L; Hunt, S M

1996-01-01

OBJECTIVE: To examine the mental health impact of different aspects of poor housing. DESIGN: This was a post hoc analysis of data from a household interview survey. SETTING: A public sector housing estate on the outskirts of Glasgow. SUBJECTS: These comprised 114 men and 333 women aged between 17 and 65 from 451 households. MEASURES: Dependent variable: scoring > or = 5 on the 30 item general health questionnaire (GHQ30). Independent variables: self reported data on household composition, whether ill health was a factor in the move to the current dwelling, length of time at address, household income, whether the respondent was employed, chronic illness, and 6 problems with the dwelling. RESULTS: Reporting a problem with dampness was significantly and independently associated with scores of > or = 5 on the GHQ30 after controlling for possible confounding variables. CONCLUSION: Initiatives to tackle housing dampness may be important in developing a strategy to improve mental health for the study area. More research on the mental health impact of different aspects of poor housing is required. PMID:8762355

Oral care experiences and challenges in children with autism spectrum disorders.

PubMed

Stein, Leah I; Polido, José C; Najera, Sandy Oliver Lopez; Cermak, Sharon A

2012-01-01

The purpose of this study was to investigate the differences between children with autism spectrum disorders (ASD) and their typically developing peers in relation to aspects of oral care. Participants included 396 parents of ASD children or typically developing 2- to 18-year-olds. Parents completed a 37-item questionnaire designed by authors to elicit information about oral care in the home and dental office. Descriptive, bivariate, and multivariate regression analyses were conducted to examine the association between diagnostic group and oral care variables. Significantly more parents of ASD children than parents of typically developing children reported difficulty across almost all oral care variables explored, including oral care in the home, oral care at the dentist, and access to oral care. Following multivariate regression to control for possible confounders-including age, gender, Hispanic status, and paternal education level-all previously significant variables remained significant. This study indicates that children with autism spectrum disorders experience greater difficulties and barriers to care in both the home and dental office settings than their typically developing peers.

Refining clinical phenotypes by contrasting ethnically different populations with schizophrenia from Australia, India and Sarawak.

PubMed

McLean, Duncan; John, Sujit; Barrett, Robert; McGrath, John; Loa, Peter; Thara, Rangaswamy; Mowry, Bryan

2012-04-30

We contrasted demographic and clinical characteristics in transethnic schizophrenia populations from Australia (n=821), India (n=520) and Sarawak, Malaysia (n=298) and proposed cultural explanations for identified site differences. From these we aimed to identify candidate variables free from significant cultural confounding that are hence suitable for inclusion in genetic analyses. We observed five phenomena: (1) more individuals were living alone in Australia than India or Sarawak; (2) drug use was lower in India than Australia or Sarawak; (3) duration of untreated psychosis (DUP) was longer in India than Australia or Sarawak; (4) the rate of schizoaffective disorder was lower in India than Australia or Sarawak; and (5) age at psychosis onset (AAO) was older in Sarawak than Australia or India. We suggest that site differences for living arrangements, drug use and DUP are culturally confounded. The schizoaffective site difference likely results from measurement bias. The AAO site difference, however, has no obvious cultural or measurement bias explanation. Therefore, this may be an ideal candidate for use in genetic studies, given that genetic variants affecting AAO have already been proposed. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

THE EXPERIMENTAL DESIGN FOR BeO IRAADIATION EXPERIMENTS ORNL 41-8 AND ORNL 41-9

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardiner, D.A.

1962-07-18

The experimental plan for irradiating BeO pellets in Experiments ORNL 41- 8 and ORNL 41-9 was chosen in accordance with the principles of experimental design. The design is known by statisticians as a 2/sup 5/ factorial experiment confound'' in six replications. Five variables---size, density, grain size, temperature and time--are controlled at two levels to form the basic 2i factorial experiment. The sixth variable, neutron flux, is introduced by confounding on higher-order interactions. An explanation is presented in nontechnical language the means by which the aims of the experimenters and the physical conditions affecting the experiment were utilized in constructing themore » experimental design. (auth)« less

The Conservative Corner of the Liberal Academy? Fraternity/Sorority Membership, Politics, and Activism

ERIC Educational Resources Information Center

Hevel, Michael S.; Weeden, Dustin D.; Pasquesi, Kira; Pascarella, Ernest T.

2015-01-01

We use a longitudinal dataset to explore the effect of fraternity/sorority membership on political orientation and social/political activism. After controlling for a variety of potentially confounding variables, including pretests on the dependent variables, fraternity and sorority members were significantly less liberal that their unaffiliated…

Beyond Free Lunch: Which Family Background Measures Matter?

ERIC Educational Resources Information Center

Lubienski, Sarah Theule; Crane, Corinna Crawford

2010-01-01

Most studies of school achievement use free-lunch eligibility or other basic indicators to adjust for differences in students' socioeconomic backgrounds. This study determines whether these variables are enough to separate the confounding effects of students' backgrounds from the main variables of interest in education studies. The Early Childhood…

Socioeconomic and air pollution correlates of adult asthma, heart attack, and stroke risks in the United States, 2010-2013.

PubMed

Cox, Louis Anthony Tony

2017-05-01

Asthma in the United States has become an important public health issue, with many physicians, regulators, and scientists elsewhere expressing concern that criterion air pollutants have contributed to a rising tide of asthma cases and symptoms. This paper studies recent associations (from 2008 to 2012) between self-reported asthma experiences and potential predictors, including age, sex, income, education, smoking, and county-level average annual ambient concentrations of ozone (O3) and fine particulate matter (PM2.5) levels recorded by the U.S. Environmental Protection Agency, for adults 50 years old or older for whom survey data are available from the Centers for Disease Control and Prevention (CDC) Behavioral Risk Factor Surveillance System (BRFSS). We also examine associations between these variables and self-reported heart attack and stroke experience; all three health outcomes are positively associated with each other. Young divorced women with low incomes are at greatest risk of asthma, especially if they are ever-smokers. Income is an important confounder of other relations. For example, in logistic regression modeling, PM2.5 is positively associated (p<0.06) with both stroke risk and heart attack risk when these are regressed only against PM2.5, sex, age, and ever-smoking status, but not when they are regressed against these variables and income. In this data set, PM2.5 is significantly negatively associated with asthma risk in regression models, with a 10μg/m 3 decrease in PM2.5 corresponding to about a 6% increase in the probability of asthma, possibly because of confounding by smoking, which is negatively associated with PM2.5 and positively associated with asthma risk. A variety of non-parametric methods are used to quantify these associations and to explore potential causal interpretations. Copyright © 2017. Published by Elsevier Inc.

The Causal Mediation Formula - A Guide to the Assessment of Pathways and Mechanisms

DTIC Science & Technology

2011-10-01

for estimating CDE(z) in observational studies (in the presence of unobserved confounders) can be derived using do- calculus (Pearl, 2009, pp. 85–88...2011; Albert and Nelson , 2011). 7In the presence of measured and unmeasured confounders, the general conditions under which NDE is estimable from...achieve this independence (see footnote 7), that Z may represent a vector of variables, and that integrals should replace summations when dealing with

Physician gender, patient gender, and primary care.

PubMed

Franks, Peter; Bertakis, Klea D

2003-01-01

Studies of the effects of physician gender on patient care have been limited by selected samples, examining a narrow spectrum of care, or not controlling for important confounders. We sought to examine the role of physician and patient gender across the spectrum of primary care in a nationally representative sample, large enough to examine the role of gender concordance and adjust for confounding variables. We examined the relationships between physician and patient gender using nationally representative samples (the U. S. National Ambulatory Medical Care Surveys from 1985 to 1992) of encounters of 41,292 adult patients with 1470 primary care physicians (internists, family physicians, and obstetrician/gynecologists). Factors examined included physician (age, gender, region, rural location), patient (age, gender, race, insurance), and visit characteristics (diagnoses, gender-specific and nonspecific prevention, duration, continuity, and disposition). After multivariate adjustment, female physicians were more likely to see female patients, had longer visit durations, and were more likely to perform female prevention procedures and make some follow-up arrangements and referrals. Female physicians were slightly more likely to check patients blood pressure, but there were no significant differences in other nongender-specific prevention procedures or use of psychiatric diagnoses. Among encounters without breast or pelvic examinations, visit length was not related to physician gender, but length was longer in gender concordant visits than gender-discordant visits. Female physicians were more likely to deliver female prevention procedures, but few other physician gender differences in primary care were observed. Physician-patient gender concordance was a key determinant of encounters.

Living in stressful neighbourhoods during pregnancy: an observational study of crime rates and birth outcomes.

PubMed

Clemens, Tom; Dibben, Chris

2017-04-01

Patterns of adverse birth outcomes vary spatially and there is evidence that this may relate to features of the physical environment such as air pollution. However, other social characteristics of the environment such as levels of crime are relatively understudied. This study examines the association between crime rates and birth weight and prematurity. Maternity inpatient data recorded at birth, including residential postcode, was linked to a representative 5% sample of Scottish Census data and small area crime rates from Scottish Police forces. Coefficients associated with crime were reported from crude and confounder adjusted models predicting low birth weight (< 2500 g), mean birthweight, small for gestational age and prematurity for all singleton live births. Total crime rates were associated with strong and significant reductions in mean birth weight and increases in the risks of both a small for gestational age baby and premature birth. These effects, with the exception of prematurity, were robust to adjustment for individual characteristics including smoking, ethnicity and other socio-economic variables as well as area based confounders including air pollution. Mean birth weight was robust to additional adjustment for neighbourhood income deprivation. The level of crime in a mother's area of residence, which may be a proxy for the degree of threat felt and therefore stress experienced, appears to be an important determinant of the risk of adverse birth outcomes. © The Author 2016. Published by Oxford University Press on behalf of the European Public Health Association.

The effects of socioeconomic status and indices of physical environment on reduced birth weight and preterm births in Eastern Massachusetts

PubMed Central

Zeka, Ariana; Melly, Steve J; Schwartz, Joel

2008-01-01

Background Air pollution and social characteristics have been shown to affect indicators of health. While use of spatial methods to estimate exposure to air pollution has increased the power to detect effects, questions have been raised about potential for confounding by social factors. Methods A study of singleton births in Eastern Massachusetts was conducted between 1996 and 2002 to examine the association between indicators of traffic, land use, individual and area-based socioeconomic measures (SEM), and birth outcomes (birth weight, small for gestational age and preterm births), in a two-level hierarchical model. Results We found effects of both individual (education, race, prenatal care index) and area-based (median household income) SEM with all birth outcomes. The associations for traffic and land use variables were mainly seen with birth weight, with an exception for an effect of cumulative traffic density on small for gestational age. Race/ethnicity of mother was an important predictor of birth outcomes and a strong confounder for both area-based SEM and indices of physical environment. The effects of traffic and land use differed by level of education and median household income. Conclusion Overall, the findings of the study suggested greater likelihood of reduced birth weight and preterm births among the more socially disadvantaged, and a greater risk of reduced birth weight associated with traffic exposures. Results revealed the importance of controlling simultaneously for SEM and environmental exposures as the way to better understand determinants of health. PMID:19032747

IV crystalloid fluid for acute alcoholic intoxication prolongs ED length of stay.

PubMed

Homma, Yosuke; Shiga, Takashi; Hoshina, Yuiko; Numata, Kenji; Mizobe, Michiko; Nakashima, Yoshiyuki; Takahashi, Jin; Inoue, Tetsuya; Takahashi, Osamu; Funakoshi, Hiraku

2018-04-01

Acute alcohol intoxication is often treated in emergency departments by intravenous crystalloid fluid (IVF), but it is not clear that this shortens the time to achieving sobriety. The study aim was to investigate the association of IVF infusion and length of stay in the ED. This single-center retrospective cohort study was conducted in Japan and included patients aged ≥20years of age and treated for acute alcohol intoxication without or with IVF. The primary outcome was the length of the ED stay and the treatments were compared by time-to-event analysis. A total of 106 patients, 42 treated without IVF and 64 with IVF. The baseline characteristics of the two groups were similar. Kaplan-Meier analysis and the generalized Wilcoxon test found no significant difference between the two treatments in the time to ED discharge. The median time was 189 (IQR 160-230) minutes without IVF and 254.5 (203-267 minutes with IVF; p=0.052). A Cox proportional hazards regression model adjusted for potential confounding variables found that patients treated with IVF were less likely to be discharged earlier than those treated without IVF (HR 0.54, 95% CI: 0.35-0.84, p=0.006). IVF for treatment of acute alcoholic intoxication prolonged ED length of stay even after adjustment for potential confounders. Patients given IVF for acute alcohol intoxication should be selected with care. Copyright © 2017 Elsevier Inc. All rights reserved.

Language Outcomes at 12 Years for Children Exposed Prenatally to Cocaine

PubMed Central

Lewis, Barbara A.; Minnes, Sonia; Short, Elizabeth J.; Min, Meeyoung O.; Wu, Miaoping; Lang, Adelaide; Weishampel, Paul; Singer, Lynn T.

2014-01-01

Purpose In this study, the authors aimed to examine the long-term effects of prenatal cocaine exposure (PCE) on the language development of 12-year-old children using a prospective design, controlling for confounding prenatal drug exposure and environmental factors. Method Children who were exposed to cocaine in utero (PCE; n = 183) and children who were not exposed to cocaine (i.e., no cocaine exposure [NCE]; n = 181) were followed prospectively from birth to 12 years of age and were compared on language subtests of the Test of Language Development—Intermediate, Third Edition (Hammill & Newcomer, 1997b), and phonological processing as measured by the Comprehensive Test of Phonological Processing (Wagner & Torgesen, 1999). The authors evaluated the relationship of PCE to language development through a multivariate analysis of covariance and regression analyses while controlling for confounders. Results Results show that PCE has small effects on specific aspects of language, including syntax and phonological processing. The caregiver variables of lower maternal vocabulary, more psychological symptoms, and a poorer home environment also had consistent effects on language and phonological processing scores. Conclusions These findings suggest that PCE continues to have small, subtle effects on specific aspects of language at age 12 years. Phonological processing skills were significantly related to the reading outcomes of letter–word identification, reading fluency, and reading comprehension, indicating that PCE also has small but lasting effects on the language skills that are related to later literacy skills. PMID:24149136

Mortality rates at 10 years after metal-on-metal hip resurfacing compared with total hip replacement in England: retrospective cohort analysis of hospital episode statistics

PubMed Central

Kendal, Adrian R; Prieto-Alhambra, Daniel; Arden, Nigel K; Judge, Andrew

2013-01-01

Objectives To compare 10 year mortality rates among patients undergoing metal-on-metal hip resurfacing and total hip replacement in England. Design Retrospective cohort study. Setting English hospital episode statistics database linked to mortality records from the Office for National Statistics. Population All adults who underwent primary elective hip replacement for osteoarthritis from April 1999 to March 2012. The exposure of interest was prosthesis type: cemented total hip replacement, uncemented total hip replacement, and metal-on-metal hip resurfacing. Confounding variables included age, sex, Charlson comorbidity index, rurality, area deprivation, surgical volume, and year of operation. Main outcome measures All cause mortality. Propensity score matching was used to minimise confounding by indication. Kaplan-Meier plots estimated the probability of survival up to 10 years after surgery. Multilevel Cox regression modelling, stratified on matched sets, described the association between prosthesis type and time to death, accounting for variation across hospital trusts. Results 7437 patients undergoing metal-on-metal hip resurfacing were matched to 22 311 undergoing cemented total hip replacement; 8101 patients undergoing metal-on-metal hip resurfacing were matched to 24 303 undergoing uncemented total hip replacement. 10 year rates of cumulative mortality were 271 (3.6%) for metal-on-metal hip resurfacing versus 1363 (6.1%) for cemented total hip replacement, and 239 (3.0%) for metal-on-metal hip resurfacing versus 999 (4.1%) for uncemented total hip replacement. Patients undergoing metal-on-metal hip resurfacing had an increased survival probability (hazard ratio 0.51 (95% confidence interval 0.45 to 0.59) for cemented hip replacement; 0.55 (0.47 to 0.65) for uncemented hip replacement). There was no evidence for an interaction with age or sex. Conclusions Patients with hip osteoarthritis undergoing metal-on-metal hip resurfacing have reduced mortality in the long term compared with those undergoing cemented or uncemented total hip replacement. This difference persisted after extensive adjustment for confounding factors available in our data. The study results can be applied to matched populations, which exclude patients who are very old and have had complex total hip replacements. Although residual confounding is possible, the observed effect size is large. These findings require validation in external cohorts and randomised clinical trials. PMID:24284336

Prognostic significance of social network, social support and loneliness for course of major depressive disorder in adulthood and old age.

PubMed

van den Brink, R H S; Schutter, N; Hanssen, D J C; Elzinga, B M; Rabeling-Keus, I M; Stek, M L; Comijs, H C; Penninx, B W J H; Oude Voshaar, R C

2018-06-01

Poor recovery from depressive disorder has been shown to be related to low perceived social support and loneliness, but not to social network size or frequency of social interactions. Some studies suggest that the significance of social relationships for depression course may be greater in younger than in older patients, and may differ between men and women. None of the studies examined to what extent the different aspects of social relationships have unique or overlapping predictive values for depression course. It is the aim of the present study to examine the differential predictive values of social network characteristics, social support and loneliness for the course of depressive disorder, and to test whether these predictive associations are modified by gender or age. Two naturalistic cohort studies with the same design and overlapping instruments were combined to obtain a study sample of 1474 patients with a major depressive disorder, of whom 1181 (80.1%) could be studied over a 2-year period. Social relational variables were assessed at baseline. Two aspects of depression course were studied: remission at 2-year follow-up and change in depression severity over the follow-up period. By means of logistic regression and random coefficient analysis, the individual and combined predictive values of the different social relational variables for depression course were studied, controlling for potential confounders and checking for effect modification by age (below 60 v. 60 years or older) and gender. Multiple aspects of the social network, social support and loneliness were related to depression course, independent of potential confounders - including depression severity - but when combined, their predictive values were found to overlap to a large extent. Only the social network characteristic of living in a larger household, the social support characteristic of few negative experiences with the support from a partner or close friend, and limited feelings of loneliness proved to have unique predictive value for a favourable course of depression. Little evidence was found for effect modification by gender or age. If depressed persons experience difficulties in their social relationships, this may impede their recovery. Special attention for interpersonal problems, social isolation and feelings of loneliness seems warranted in depression treatment and relapse prevention. It will be of great interest to test whether social relational interventions can contribute to better recovery and relapse prevention of depressive disorder.

Measuring the surgical 'learning curve': methods, variables and competency.

PubMed

Khan, Nuzhath; Abboudi, Hamid; Khan, Mohammed Shamim; Dasgupta, Prokar; Ahmed, Kamran

2014-03-01

To describe how learning curves are measured and what procedural variables are used to establish a 'learning curve' (LC). To assess whether LCs are a valuable measure of competency. A review of the surgical literature pertaining to LCs was conducted using the Medline and OVID databases. Variables should be fully defined and when possible, patient-specific variables should be used. Trainee's prior experience and level of supervision should be quantified; the case mix and complexity should ideally be constant. Logistic regression may be used to control for confounding variables. Ideally, a learning plateau should reach a predefined/expert-derived competency level, which should be fully defined. When the group splitting method is used, smaller cohorts should be used in order to narrow the range of the LC. Simulation technology and competence-based objective assessments may be used in training and assessment in LC studies. Measuring the surgical LC has potential benefits for patient safety and surgical education. However, standardisation in the methods and variables used to measure LCs is required. Confounding variables, such as participant's prior experience, case mix, difficulty of procedures and level of supervision, should be controlled. Competency and expert performance should be fully defined. © 2013 The Authors. BJU International © 2013 BJU International.

Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system

USGS Publications Warehouse

Cloern, J.E.; Canuel, E.A.; Harris, D.

2002-01-01

We report measurements of seasonal variability in the C-N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh) to determine whether C-N isotopes can be used as biomarkers for tracing the origins of organic matter in this river-marsh-estuary complex. Variability of ??13C and ??15N was high (???5-10???) within each plant group, and we identified three modes of variability: (1) between species and their microhabitats, (2) over annual cycles of plant growth and senescence, and (3) between living and decomposing biomass. These modes of within-group variability obscure any source-specific isotopic signatures, confounding the application of C-N isotopes for identifying the origins of organic matter. A second confounding factor was large dissimilarity between the ??13C-??15N of primary producers and the organic-matter pools in the seston and sediments. Both confounding factors impede the application of C-N isotopes to reveal the food supply to primary consumers in ecosystems supporting diverse autotrophs and where the isotopic composition of organic matter has been transformed and become distinct from that of its parent plant sources. Our results support the advice of others: variability of C-N stable isotopes within all organic-matter pools is high and must be considered in applications of these isotopes to trace trophic linkages from primary producers to primary consumers. Isotope-based approaches are perhaps most powerful when used to complement other tools, such as molecular biomarkers, bioassays, direct measures of production, and compilations of organic-matter budgets.

Pregnancy context and women's health-related quality of life.

PubMed

Gariepy, Aileen; Lundsberg, Lisbet S; Vilardo, Nicole; Stanwood, Nancy; Yonkers, Kimberly; Schwarz, Eleanor B

2017-05-01

The objective was to quantify the association of pregnancy context and health-related quality of life (HRQoL). English- or Spanish-speaking women, aged 16-44, with pregnancies <24 weeks' gestation were enrolled in this cross-sectional study between June 2014 and June 2015. Participants completed self-assessments of pregnancy "context," including timing, intention, wantedness, desirability, happiness, and planning (measured with the London Measure of Unplanned Pregnancy). HRQoL was measured using the Patient Reported Outcomes Measurement Information System Global Short Form. Associations between measures of pregnancy context and HRQoL scores in the lowest tertile were examined using multivariable logistic regression to adjust for potential confounding variables. We enrolled 161 participants (mean age=27.2±6.6 years). Only 14% self-identified as White, non-Hispanic; 42% Hispanic; 37% Black, non-Hispanic; and 7% multiracial. Most (79%) participants were unmarried, and 75% were parenting. Mean gestational age was 9±4.6 weeks. In unadjusted models, women reporting mixed feelings about wanting to have a baby, an undesired pregnancy or feeling unhappy about learning of their pregnancy more frequently had low mental and physical HRQoL compared to women reporting wanted, desired, happy pregnancies. Women with an unplanned pregnancy or pregnancy occurring at the wrong time also had lower physical HRQoL than women reporting pregnancies that were planned or happened at the right time. However, after multivariate adjustment, including history of depression, pregnancy contexts were not associated with low mental or physical HRQoL. After adjusting for multiple confounders, pregnancy context is not significantly associated with HRQoL. The focus on pregnancy intention in public health programs may not sufficiently assess multidimensional aspects of pregnancy context and may not align with patient-centered outcomes such as HRQoL. Copyright © 2017 Elsevier Inc. All rights reserved.

Fitness and adiposity as predictors of functional limitation in adults.

PubMed

Maslow, Andréa L; Price, Anna E; Sui, Xuemei; Lee, Duck-chul; Vuori, Ikka; Blair, Steven N

2011-01-01

This study examined the associations of body mass index (BMI), waist circumference (WC), and cardiorespiratory fitness (CRF) with incident functional limitation (IFL) in adults. Patients (n = 2400), 30+ years [mean age, 45.2 (SD, 8.3); 12% women], completed a baseline health examination during 1979 to 1995. CRF was quantified by age-and sex-specific thirds for maximal treadmill exercise test duration. Adiposity was assessed by BMI and WC (grouped for analysis according to clinical guidelines). Incident IFL was identified from mail-back surveys during 1995, 1999, and 2004. After adjusting for potential confounders and either BMI or WC, CRF was inversely related to IFL (P trend < .001). The association between BMI and IFL was significant after adjusting for all confounders (P trend = .002), but not after additional adjustment for CRF (P trend = .23). After controlling for all confounders and CRF, high WC was associated with greater odds of IFL in those aged 30 to 49; normal WC was associated with greater odds of IFL in those aged 50+. CRF was a significant predictor of IFL in middle aged and older adults, independent of overall or abdominal adiposity. Clinicians should consider the importance of preserving functional capacity by recommending regular physical activity for normal-weight and overweight individuals. ©2011 Human Kinetics, Inc.

Do schools differ in suicide risk? The influence of school and neighbourhood on attempted suicide, suicidal ideation and self-harm among secondary school pupils.

PubMed

Young, Robert; Sweeting, Helen; Ellaway, Anne

2011-11-17

Rates of suicide and poor mental health are high in environments (neighbourhoods and institutions) where individuals have only weak social ties, feel socially disconnected and experience anomie - a mismatch between individual and community norms and values. Young people spend much of their time within the school environment, but the influence of school context (school connectedness, ethos and contextual factors such as school size or denomination) on suicide-risk is understudied. Our aim is to explore if school context is associated with rates of attempted suicide and suicide-risk at age 15 and self-harm at age 19, adjusting for confounders. A longitudinal school-based survey of 1698 young people surveyed when aged 11, (primary school), 15 (secondary school) and in early adulthood (age 19). Participants provided data about attempted suicide and suicide-risk at age 15 and deliberate self-harm at 19. In addition, data were collected about mental health at age 11, social background (gender, religion, etc.), and at age 15, perception of local area (e.g. neighbourhood cohesion, safety/civility and facilities), school connectedness (school engagement, involvement, etc.) and school context (size, denomination, etc.). A dummy variable was created indicating a religious 'mismatch', where pupils held a different faith from their school denomination. Data were analysed using multilevel logistic regression. After adjustment for confounders, pupils attempted suicide, suicide-risk and self-harm were all more likely among pupils with low school engagement (15-18% increase in odds for each SD change in engagement). While holding Catholic religious beliefs was protective, attending a Catholic school was a risk factor for suicidal behaviours. This pattern was explained by religious 'mismatch': pupils of a different religion from their school were approximately 2-4 times more likely to attempt suicide, be a suicide-risk or self-harm. With several caveats, we found support for the importance of school context for suicidality and self-harm. School policies promoting school connectedness are uncontroversial. Devising a policy to reduce risks to pupils holding a different faith from that of their school may be more problematic.

Do schools differ in suicide risk? the influence of school and neighbourhood on attempted suicide, suicidal ideation and self-harm among secondary school pupils

PubMed Central

2011-01-01

Background Rates of suicide and poor mental health are high in environments (neighbourhoods and institutions) where individuals have only weak social ties, feel socially disconnected and experience anomie - a mismatch between individual and community norms and values. Young people spend much of their time within the school environment, but the influence of school context (school connectedness, ethos and contextual factors such as school size or denomination) on suicide-risk is understudied. Our aim is to explore if school context is associated with rates of attempted suicide and suicide-risk at age 15 and self-harm at age 19, adjusting for confounders. Methods A longitudinal school-based survey of 1698 young people surveyed when aged 11, (primary school), 15 (secondary school) and in early adulthood (age 19). Participants provided data about attempted suicide and suicide-risk at age 15 and deliberate self-harm at 19. In addition, data were collected about mental health at age 11, social background (gender, religion, etc.), and at age 15, perception of local area (e.g. neighbourhood cohesion, safety/civility and facilities), school connectedness (school engagement, involvement, etc.) and school context (size, denomination, etc.). A dummy variable was created indicating a religious 'mismatch', where pupils held a different faith from their school denomination. Data were analysed using multilevel logistic regression. Results After adjustment for confounders, pupils attempted suicide, suicide-risk and self-harm were all more likely among pupils with low school engagement (15-18% increase in odds for each SD change in engagement). While holding Catholic religious beliefs was protective, attending a Catholic school was a risk factor for suicidal behaviours. This pattern was explained by religious 'mismatch': pupils of a different religion from their school were approximately 2-4 times more likely to attempt suicide, be a suicide-risk or self-harm. Conclusions With several caveats, we found support for the importance of school context for suicidality and self-harm. School policies promoting school connectedness are uncontroversial. Devising a policy to reduce risks to pupils holding a different faith from that of their school may be more problematic. PMID:22093491

Foraminiferal faunal estimates of paleotemperature: Circumventing the no-analog problem yields cool ice age tropics

USGS Publications Warehouse

Mix, A.C.; Morey, A.E.; Pisias, N.G.; Hostetler, S.W.

1999-01-01

The sensitivity of the tropics to climate change, particularly the amplitude of glacial-to-interglacial changes in sea surface temperature (SST), is one of the great controversies in paleoclimatology. Here we reassess faunal estimates of ice age SSTs, focusing on the problem of no-analog planktonic foraminiferal assemblages in the equatorial oceans that confounds both classical transfer function and modern analog methods. A new calibration strategy developed here, which uses past variability of species to define robust faunal assemblages, solves the no-analog problem and reveals ice age cooling of 5??to 6??C in the equatorial current systems of the Atlantic and eastern Pacific Oceans. Classical transfer functions underestimated temperature changes in some areas of the tropical oceans because core-top assemblages misrepresented the ice age faunal assemblages. Our finding is consistent with some geochemical estimates and model predictions of greater ice age cooling in the tropics than was inferred by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981] and thus may help to resolve a long-standing controversy. Our new foraminiferal transfer function suggests that such cooling was limited to the equatorial current systems, however, and supports CLIMAP's inference of stability of the subtropical gyre centers.

Identifying cis-mediators for trans-eQTLs across many human tissues using genomic mediation analysis

PubMed Central

Yang, Fan; Wang, Jiebiao; Pierce, Brandon L.; Chen, Lin S.

2017-01-01

The impact of inherited genetic variation on gene expression in humans is well-established. The majority of known expression quantitative trait loci (eQTLs) impact expression of local genes (cis-eQTLs). More research is needed to identify effects of genetic variation on distant genes (trans-eQTLs) and understand their biological mechanisms. One common trans-eQTLs mechanism is “mediation” by a local (cis) transcript. Thus, mediation analysis can be applied to genome-wide SNP and expression data in order to identify transcripts that are “cis-mediators” of trans-eQTLs, including those “cis-hubs” involved in regulation of many trans-genes. Identifying such mediators helps us understand regulatory networks and suggests biological mechanisms underlying trans-eQTLs, both of which are relevant for understanding susceptibility to complex diseases. The multitissue expression data from the Genotype-Tissue Expression (GTEx) program provides a unique opportunity to study cis-mediation across human tissue types. However, the presence of complex hidden confounding effects in biological systems can make mediation analyses challenging and prone to confounding bias, particularly when conducted among diverse samples. To address this problem, we propose a new method: Genomic Mediation analysis with Adaptive Confounding adjustment (GMAC). It enables the search of a very large pool of variables, and adaptively selects potential confounding variables for each mediation test. Analyses of simulated data and GTEx data demonstrate that the adaptive selection of confounders by GMAC improves the power and precision of mediation analysis. Application of GMAC to GTEx data provides new insights into the observed patterns of cis-hubs and trans-eQTL regulation across tissue types. PMID:29021290

Identifying cis-mediators for trans-eQTLs across many human tissues using genomic mediation analysis.

PubMed

Yang, Fan; Wang, Jiebiao; Pierce, Brandon L; Chen, Lin S

2017-11-01

The impact of inherited genetic variation on gene expression in humans is well-established. The majority of known expression quantitative trait loci (eQTLs) impact expression of local genes ( cis -eQTLs). More research is needed to identify effects of genetic variation on distant genes ( trans -eQTLs) and understand their biological mechanisms. One common trans -eQTLs mechanism is "mediation" by a local ( cis ) transcript. Thus, mediation analysis can be applied to genome-wide SNP and expression data in order to identify transcripts that are " cis -mediators" of trans -eQTLs, including those " cis -hubs" involved in regulation of many trans -genes. Identifying such mediators helps us understand regulatory networks and suggests biological mechanisms underlying trans -eQTLs, both of which are relevant for understanding susceptibility to complex diseases. The multitissue expression data from the Genotype-Tissue Expression (GTEx) program provides a unique opportunity to study cis -mediation across human tissue types. However, the presence of complex hidden confounding effects in biological systems can make mediation analyses challenging and prone to confounding bias, particularly when conducted among diverse samples. To address this problem, we propose a new method: Genomic Mediation analysis with Adaptive Confounding adjustment (GMAC). It enables the search of a very large pool of variables, and adaptively selects potential confounding variables for each mediation test. Analyses of simulated data and GTEx data demonstrate that the adaptive selection of confounders by GMAC improves the power and precision of mediation analysis. Application of GMAC to GTEx data provides new insights into the observed patterns of cis -hubs and trans -eQTL regulation across tissue types. © 2017 Yang et al.; Published by Cold Spring Harbor Laboratory Press.

The association between social network relationships and depressive symptoms among older Americans: what matters most?

PubMed

Litwin, Howard

2011-08-01

Although social network relationships are linked to mental health in late life, it is still unclear whether it is the structure of social networks or their perceived quality that matters. The current study regressed a dichotomous 8-item version of the Center for Epidemiological Studies Depression Scale (CESD-8) score on measures of social network relationships among Americans, aged 65-85 years, from the first wave of the National Social Life, Health and Aging Project. The network indicators included a structural variable - social network type - and a series of relationship quality indicators: perceived positive and negative ties with family, friends and spouse/ partner. Multivariate logistic regression analyses controlled for age, gender, education, income, race/ethnicity, religious affiliation, functional health and physical health. The perceived social network quality variables were unrelated to the presence of a high level of depressive symptoms, but social network type maintained an association with this mental health outcome even after controlling for confounders. Respondents embedded in resourceful social network types in terms of social capital--"diverse," "friend" and "congregant" networks--reported less presence of depressive symptoms, to varying degrees. The results show that the structure of the network seems to matter more than the perceived quality of the ties as an indicator of depressive symptoms. Moreover, the composite network type variable stands out in capturing the differences in mental state. The construct of network type should be incorporated in mental health screening among older people who reside in the community. One's social network type can be an important initial indicator that one is at risk.

HEAVY MANUAL WORK THROUGHOUT THE WORKING LIFETIME AND MUSCLE STRENGTH AMONG MEN AT RETIREMENT AGE

PubMed Central

Walker-Bone, K; D’Angelo, S; Syddall, HE; Palmer, KT; Cooper, C; Coggon, D; Sayer, AA

2016-01-01

Introduction Reductions in heavy manual work as a consequence of mechanisation might impact adversely on muscle strength at older ages. We investigated the association between grip strength at retirement age and lifetime occupational exposure to physically demanding activities. Grip strength is an important predictor of long-term health and physical function in older people. Methods Grip strength (maximum of three readings in each hand) was measured in men from the Hertfordshire Cohort Study at a single examination when their mean age was 65.8 (SD 2.9) years. Associations with lifetime occupational exposure (ascertained by questionnaire) to three activities (standing/walking ≥4 hours/day; lifting ≥25 kg; and energetic work sufficient to induce sweating) were assessed by multivariable linear regression with adjustment for various potential confounders. Results Complete data were available from 1,418 men who had worked for at least 20 years. After adjustment for age, height and weight, those with longer exposures to walking/standing and heavy lifting had lower grip strength, but the relationship disappeared after further adjustment for confounders. Working at physical intensity sufficient to induce sweating was not significantly associated with grip strength. Conclusions We found no evidence that physically demanding occupational activities increase hand grip strength at normal retirement age. Any advantages of regular physical occupational activity may have been obscured by unmeasured socio-economic confounders. PMID:26896253

Physical Activity and Bone Health in Schoolchildren: The Mediating Role of Fitness and Body Fat

PubMed Central

Torres-Costoso, Ana; Gracia-Marco, Luis; Sánchez-López, Mairena; Notario-Pacheco, Blanca; Arias-Palencia, Natalia; Martínez-Vizcaíno, Vicente

2015-01-01

Background The relationship between physical activity (PA) and bone health is well known, although the role of percent body fat (%BF) and fitness as confounders or mediators in this relationship remains uncertain. Objective To examine whether the association between PA and bone mineral content (BMC) is mediated by %BF and cardiorespiratory fitness (CRF). Methods In this cross sectional study, BMC, total %BF (by DXA), vigorous PA (VPA), CRF, age and height were measured in 132 schoolchildren (62 boys, aged 8–11 years). ANCOVA was used to test differences in BMC by %BF, CRF and VPA, controlling for different sets of confounders. Simple mediation analyses and serial multiple mediation analyses were fitted to examine whether the relationship between PA and BMC is mediated by %BF and fitness. Results Children with high %BF had higher total body BMC than their peers after controlling for all sets of confounders. Children with good CRF or VPA had significantly less total body BMC after controlling for age and sex but in children with good CRF this inverse relation disappeared after adjusting by %BF. %BF and CRF both act as a full mediator in the association between VPA and BMC, after inclusion of the potential confounders in the models. Conclusion Fitness and %BF seem to have a mediator role on the relationship between physical activity and bone mass. PMID:25915941

Increased Putamen and Callosal Motor Subregion in Treatment-Naive Boys with Tourette Syndrome Indicates Changes in the Bihemispheric Motor Network

ERIC Educational Resources Information Center

Roessner, Veit; Overlack, Sebastian; Schmidt-Samoa, Carsten; Baudewig, Jurgen; Dechent, Peter; Rothenberger, Aribert; Helms, Gunther

2011-01-01

Background: Despite an increasing number of studies, findings of structural brain alterations in patients with Tourette syndrome are still inconsistent. Several confounders (comorbid conditions, medication, gender, age, IQ) might explain these discrepancies. In the present study, these confounders were excluded to identify differences in basal…

The death(s) of close friends and family moderate genetic influences on symptoms of major depressive disorder in adolescents.

PubMed

Gheyara, S; Klump, K L; McGue, M; Iacono, W G; Burt, S A

2011-04-01

Prior work has suggested that genetic influences on major depressive disorder (MDD) may be activated by the experience of negative life events. However, it is unclear whether these results persist when controlling for the possibility of confounding active gene-environment correlations (rGE). We examined a sample of 1230 adopted and biological siblings between the ages of 10 and 20 years from the Sibling Interaction and Behavior Study. MDD was measured via a lifetime DSM-IV symptom count. Number of deaths experienced served as our environmental risk experience. Because this variable is largely independent of the individual's choices/behaviors, we were able to examine gene-environment interactions while circumventing possible rGE confounds. Biometric analyses revealed pronounced linear increases in the magnitude of genetic influences on symptoms of MDD with the number of deaths experienced, such that genetic influences were estimated to be near-zero for those who had experienced no deaths but were quite large in those who had experienced two or more deaths (i.e. accounting for roughly two-thirds of the phenotypic variance). By contrast, shared and non-shared environmental influences on symptoms of MDD were not meaningfully moderated by the number of deaths experienced. Such results constructively replicate prior findings of genetic moderation of depressive symptoms by negative life events, thereby suggesting that this effect is not a function of active rGE confounds. Our findings are thus consistent with the notion that exposure to specific negative life events may serve to activate genetic risk for depression during adolescence.

Lifetime Alcohol Use & Cognitive Performance in Older Adults

PubMed Central

Kalapatapu, Raj K.; Ventura, Maria I.; Barnes, Deborah E.

2016-01-01

Background Substance use is an important clinical issue in the older adult population. As older adults are susceptible to cognitive disorders, the intersection of the fields of substance use and cognitive neuroscience is an active area of research. Prior studies of alcohol use and cognitive performance are mixed, and inconsistencies may be due to under- or over-adjustment for confounders. Aim This manuscript adds to this literature by conducting a secondary analysis of self-reported lifetime history of alcohol use and cognitive performance in older adults (n = 133). We hypothesized that current alcohol users would have poorer cognitive performance compared to never/minimal and former alcohol users. Methods Older adult participants were classified into never/minimal alcohol users, former alcohol users, and current alcohol users. A neurocognitive battery included a global cognitive measure and individual measures of attention, memory, fluency, and executive function. A directed acyclic graph (DAG)-based approach was used to select variables to be included in the multiple linear regression models. Results Though unadjusted analyses showed some significant associations between alcohol use and cognitive performance, all associations between alcohol use and cognitive performance were eliminated after adjusting for age, education, sex, race and smoking pack years. Alcohol drink years were not significantly associated with cognitive performance among current and former alcohol users. Discussion These results suggest that lifetime alcohol use is not significantly associated with cognitive performance in older adults after adjustment for key confounders. Inconsistencies in prior studies may be due to uncontrolled confounding and/or unnecessary adjustment of mediators and/or colliders. PMID:27719514

Cross-Sectional and Longitudinal Associations between Household Food Security and Child Anthropometry at Ages 5 and 8 Years in Ethiopia, India, Peru, and Vietnam123

PubMed Central

Humphries, Debbie L; Dearden, Kirk A; Crookston, Benjamin T; Fernald, Lia C; Stein, Aryeh D; Woldehanna, Tassew; Penny, Mary E; Behrman, Jere R

2015-01-01

Background: Poor childhood nutritional status has lifetime effects and food insecurity is associated with dietary practices that can impair nutritional status. Objectives: We assessed concurrent and subsequent associations between food insecurity and height-for-age z scores (HAZs) and body mass index–for-age z scores (BMI-Zs); evaluated associations with transitory and chronic food insecurity; and tested whether dietary diversity mediates associations between food insecurity and nutritional status. Methods: We used data from the Young Lives younger cohort composed of children in Ethiopia (n = 1757), India (n = 1825), Peru (n = 1844), and Vietnam (n = 1828) recruited in 2002 (round 1) at ∼1 y old, with subsequent data collection at 5 y in 2006 (round 2) and 8 y in 2009 (round 3). Results: Children from food-insecure households had significantly lower HAZs in all countries at 5 y (Ethiopia, −0.33; India, −0.53; Peru, −0.31; and Vietnam, −0.68 HAZ; all P < 0.001), although results were attenuated after controlling for potential confounders (Ethiopia, −0.21; India, −0.32; Peru, −0.14; and Vietnam, −0.27 HAZ; P < 0.01). Age 5 y food insecurity predicted the age 8 y HAZ, but did not add predictive power beyond HAZ at age 5 y in Ethiopia, India, or Peru. Age 5 y food insecurity predicted the age 8 y BMI-Z even after controlling for the 5 y BMI-Z, although associations were not significant after the inclusion of additional confounding variables (Ethiopia, P = 0.12; India, P = 0.29; Peru, P = 0.16; and Vietnam, P = 0.51). Chronically food-insecure households had significantly lower HAZs than households that were consistently food-secure, although BMI-Zs did not differ by chronic food-insecurity status. Dietary diversity mediated 18.8–30.5% of the association between food security and anthropometry in Vietnam, but mediated to a lesser degree (8.4–19.3%) in other countries. Conclusions: In 4 countries, food insecurity at 5 y of age was associated with both HAZ and BMI-Z at age 8 y, although the association was attenuated after adjusting for other household factors and anthropometry at age 5 y, and remained significant only for the HAZ in Vietnam. PMID:26084361

Cross-Sectional and Longitudinal Associations between Household Food Security and Child Anthropometry at Ages 5 and 8 Years in Ethiopia, India, Peru, and Vietnam.

PubMed

Humphries, Debbie L; Dearden, Kirk A; Crookston, Benjamin T; Fernald, Lia C; Stein, Aryeh D; Woldehanna, Tassew; Penny, Mary E; Behrman, Jere R

2015-08-01

Poor childhood nutritional status has lifetime effects and food insecurity is associated with dietary practices that can impair nutritional status. We assessed concurrent and subsequent associations between food insecurity and height-for-age z scores (HAZs) and body mass index-for-age z scores (BMI-Zs); evaluated associations with transitory and chronic food insecurity; and tested whether dietary diversity mediates associations between food insecurity and nutritional status. We used data from the Young Lives younger cohort composed of children in Ethiopia (n = 1757), India (n = 1825), Peru (n = 1844), and Vietnam (n = 1828) recruited in 2002 (round 1) at ∼1 y old, with subsequent data collection at 5 y in 2006 (round 2) and 8 y in 2009 (round 3). Children from food-insecure households had significantly lower HAZs in all countries at 5 y (Ethiopia, -0.33; India, -0.53; Peru, -0.31; and Vietnam, -0.68 HAZ; all P < 0.001), although results were attenuated after controlling for potential confounders (Ethiopia, -0.21; India, -0.32; Peru, -0.14; and Vietnam, -0.27 HAZ; P < 0.01). Age 5 y food insecurity predicted the age 8 y HAZ, but did not add predictive power beyond HAZ at age 5 y in Ethiopia, India, or Peru. Age 5 y food insecurity predicted the age 8 y BMI-Z even after controlling for the 5 y BMI-Z, although associations were not significant after the inclusion of additional confounding variables (Ethiopia, P = 0.12; India, P = 0.29; Peru, P = 0.16; and Vietnam, P = 0.51). Chronically food-insecure households had significantly lower HAZs than households that were consistently food-secure, although BMI-Zs did not differ by chronic food-insecurity status. Dietary diversity mediated 18.8-30.5% of the association between food security and anthropometry in Vietnam, but mediated to a lesser degree (8.4-19.3%) in other countries. In 4 countries, food insecurity at 5 y of age was associated with both HAZ and BMI-Z at age 8 y, although the association was attenuated after adjusting for other household factors and anthropometry at age 5 y, and remained significant only for the HAZ in Vietnam. © 2015 American Society for Nutrition.

“Skill of Generalized Additive Model to Detect PM2.5 Health ...

EPA Pesticide Factsheets

Summary. Measures of health outcomes are collinear with meteorology and air quality, making analysis of connections between human health and air quality difficult. The purpose of this analysis was to determine time scales and periods shared by the variables of interest (and by implication scales and periods that are not shared). Hospital admissions, meteorology (temperature and relative humidity), and air quality (PM2.5 and daily maximum ozone) for New York City during the period 2000-2006 were decomposed into temporal scales ranging from 2 days to greater than two years using a complex wavelet transform. Health effects were modeled as functions of the wavelet components of meteorology and air quality using the generalized additive model (GAM) framework. This simulation study showed that GAM is extremely successful at extracting and estimating a health effect embedded in a dataset. It also shows that, if the objective in mind is to estimate the health signal but not to fully explain this signal, a simple GAM model with a single confounder (calendar time) whose smooth representation includes a sufficient number of constraints is as good as a more complex model.Introduction. In the context of wavelet regression, confounding occurs when two or more independent variables interact with the dependent variable at the same frequency. Confounding also acts on a variety of time scales, changing the PM2.5 coefficient (magnitude and sign) and its significance ac

Childhood trauma is not a confounder of the overlap between autistic and schizotypal traits: A study in a non-clinical adult sample.

PubMed

Gong, Jing-Bo; Wang, Ya; Lui, Simon S Y; Cheung, Eric F C; Chan, Raymond C K

2017-11-01

Childhood trauma has been shown to be a robust risk factor for mental disorders, and may exacerbate schizotypal traits or contribute to autistic trait severity. However, little is known whether childhood trauma confounds the overlap between schizotypal traits and autistic traits. This study examined whether childhood trauma acts as a confounding variable in the overlap between autistic and schizotypal traits in a large non-clinical adult sample. A total of 2469 participants completed the Autism Spectrum Quotient (AQ), the Schizotypal Personality Questionnaire (SPQ), and the Childhood Trauma Questionnaire-Short Form. Correlation analysis showed that the majority of associations between AQ variables and SPQ variables were significant (p < 0.05). In the multiple regression models predicting scores on the AQ total, scores on the three SPQ subscales were significant predictors(Ps < 0.05). Scores on the Positive schizotypy and Negative schizotypy subscales were significant predictors in the multiple regression model predicting scores on the AQ Social Skill, AQ Attention Switching, AQ Attention to Detail, AQ Communication, and AQ Imagination subscales. The association between autistic and schizotypal traits could not be explained by shared variance in terms of exposure to childhood trauma. The findings point to important overlaps in the conceptualization of ASD and SSD, independent of childhood trauma. Copyright © 2017 Elsevier B.V. All rights reserved.

Associations of Cannabis and Cigarette Use with Depression and Anxiety at Age 18: Findings from the Avon Longitudinal Study of Parents and Children

PubMed Central

Gage, Suzanne H.; Hickman, Matthew; Heron, Jon; Munafò, Marcus R.; Lewis, Glyn; Macleod, John; Zammit, Stanley

2015-01-01

Introduction Substance use is associated with common mental health disorders, but the causal effect of specific substances is uncertain. We investigate whether adolescent cannabis and cigarette use is associated with incident depression and anxiety, while attempting to account for confounding and reverse causation. Methods We used data from ALSPAC, a UK birth cohort study, to investigate associations between cannabis or cigarettes (measured at age 16) and depression or anxiety (measured at age 18), before and after adjustment for pre-birth, childhood and adolescent confounders. Our imputed sample size was 4561 participants. Results Both cannabis (unadjusted OR 1.50, 95% CI 1.26, 1.80) and cigarette use (OR 1.37, 95% CI 1.16, 1.61) increased the odds of developing depression. Adjustment for pre-birth and childhood confounders partly attenuated these relationships though strong evidence of association persisted for cannabis use. There was weak evidence of association for cannabis (fully adjusted OR 1.30, 95% CI 0.98, 1.72) and insufficient evidence for association for cigarette use (fully adjusted OR = 0.97, 95% CI 0.75, 1.24) after mutually adjusting for each other, or for alcohol or other substance use. Neither cannabis nor cigarette use were associated with anxiety after adjustment for pre-birth and childhood confounders. Conclusions Whilst evidence of association between cannabis use and depression persisted after adjusting for pre-term and childhood confounders, our results highlight the difficulties in trying to estimate and interpret independent effects of cannabis and tobacco on psychopathology. Complementary methods are required to robustly examine effects of cannabis and tobacco on psychopathology. PMID:25875443

"Fundamental Causes" of Social Inequalities in Mortality: A Test of the Theory

ERIC Educational Resources Information Center

Phelan, Jo C.; Link, Bruce G.; Diez-Roux, Ana; Kawachi, Ichiro; Levin, Bruce

2004-01-01

Medicine and epidemiology currently dominate the study of the strong association between socioeconomic status and mortality. Socioeconomic status typically is viewed as a causally irrelevant "confounding variable" or as a less critical variable marking only the beginning of a causal chain in which intervening risk factors are given prominence. Yet…

Predicting Teacher Value-Added Results in Non-Tested Subjects Based on Confounding Variables: A Multinomial Logistic Regression

ERIC Educational Resources Information Center

Street, Nathan Lee

2017-01-01

Teacher value-added measures (VAM) are designed to provide information regarding teachers' causal impact on the academic growth of students while controlling for exogenous variables. While some researchers contend VAMs successfully and authentically measure teacher causality on learning, others suggest VAMs cannot adequately control for exogenous…

Are Attractive Men's Faces Masculine or Feminine? The Importance of Controlling Confounds in Face Stimuli

ERIC Educational Resources Information Center

Debruine, Lisa M.; Jones, Benedict C.; Smith, Finlay G.; Little, Anthony C.

2010-01-01

Women's preferences for male masculinity are highly variable. Although many researchers explain this variability as reflecting systematic individual differences in how women resolve the tradeoff between the costs and benefits of choosing a masculine partner, others suggest that methodological differences between studies are responsible. A recent…

Adolescent Substance Use, Sleep, and Academic Achievement: Evidence of Harm Due to Caffeine

ERIC Educational Resources Information Center

James, Jack E.; Kristjansson, Alfgeir Logi; Sigfusdottir, Inga Dora

2011-01-01

Using academic achievement as the key outcome variable, 7377 Icelandic adolescents were surveyed for cigarette smoking, alcohol use, daytime sleepiness, caffeine use, and potential confounders. Structural equation modeling (SEM) was used to examine direct and indirect effects of measured and latent variables in two models: the first with caffeine…

The risk of falls and fractures associated with persistent use of psychotropic medications in elderly people.

PubMed

Vitry, Agnes I; Hoile, Annabel P; Gilbert, Andrew L; Esterman, Adrian; Luszcz, Mary A

2010-01-01

The aim of this study was to examine the effect of psychotropic medications (antipsychotics, antidepressants, anxiolytics, hypnotics and sedatives) on the risk of falls and fractures in a cohort of elderly people in South Australia. A retrospective cohort study was undertaken using the wave 1 (1992) and wave 3 (1994) data of the Australian Longitudinal Study of Ageing (ALSA). Persistent use of psychotropic medicines was defined as use of one or more psychotropic medications at both wave 1 and wave 3. A comprehensive list of potential confounding variables was individually entered into regression models to examine effects on risk ratios. The results showed that the use of psychotropic medications was associated with an increased risk of falls in females (IRR=1.47, 95% CI=1.31-1.64) but not in males (IRR=1.03, 95% CI=0.85-1.26). The use of psychotropic medications was also associated with an increased risk of a fracture in females (RR 2.54; CI 1.57-4.11; p<0.0001) but not in males (RR=0.66; p=0.584; CI 0.15-2.86). In both analyses, the body mass index (BMI) was determined to be the only confounding variable. After adjusting for BMI, the IRR in females decreased to 1.22 (95% CI 1.02-1.45; p<0.015) for falls and the RR decreased to 1.92 (p<0.015, CI 1.13-3.24) for fractures. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

Association Between National Board Dental Examination Part II Scores and Comprehensive Examinations at Harvard School of Dental Medicine.

PubMed

Lee, Min Kyeong; Allareddy, Veerasathpurush; Howell, T Howard; Karimbux, Nadeem Y

2011-01-01

Harvard School of Dental Medicine (HSDM) uses a hybrid problem-based approach to teaching in the predoctoral program. The objective structured clinical examination (OSCE) is a formative examination designed to assess the performance of students in the problem-based learning (PBL) curriculum. At HSDM three comprehensive examinations with OSCE components are administered during the third and fourth years of clinical training. The National Board Dental Examination (NBDE) Part II is taken in the final year of the predoctoral program. This study examines the association between the NBDE Part II and the comprehensive exams held at HSDM. Predoctoral students from the HSDM classes of 2005 and 2006 were included in this study. The outcome variable of interest was the scores obtained by students in the NBDE Part II, and the main independent variable of interest was the performance of students in the comprehensive exams (honors, pass, make-up exam to pass). The Mann-Whitney U-test was used to examine the association between the grades obtained in the each of the three comprehensive exams and the NBDE Part II scores. Multivariable linear regression analysis was also used to examine the association between the NBDE Part II scores and the comprehensive exam grades. The effect of potential confounding factors including age, sex, and race/ethnicity was adjusted. The results suggest that students who performed well in the comprehensive exams performed better on the NBDE Part II, even after adjusting for confounding factors. Future studies will examine the long-term impact of PBL on postdoctoral plans and career choices.

Early maternal serum ß-human chorionic gonadotropin (ß-hCG) levels and sex-related growth difference of IVF embryos.

PubMed

Esh-Broder, Efrat; Oron, Galia; Son, Weon-Young; Holzer, Hananel; Tulandi, Togas

2015-10-01

Maternal serum ß-human chorionic gonadotropin (ß-hCG) represents the trophoblastic cell mass and is an indirect measurement of embryo development at early implantation stage. Studies in animals and human embryos detected sex-related growth differences (SRGD) in favour of male embryos during the pre-implantation period. The purpose of our study was to correlate SRGD and maternal serum ß-hCG at 16 days after embryo transfer. We retrospectively analysed all (fresh and frozen) non-donor, single embryo transfers (SET), elective and not elective, that were performed between December 2008 and December 2013. We included ß-hCG values from day 16 after oocyte collection of pregnancies resulting in live birth. Neonatal gender was retrieved from patient files. Male and female embryos were further grouped to cleavage and blastocyst stage transfers. Regression analysis for confounding variables included maternal age, maternal body mass index (BMI), use of micromanipulation (ICSI), embryo quality (grade), assisted hatching, day of transfer and fresh or frozen embryo transfer. Seven hundred eighty-six non-donor SETs resulted in live birth. After including only day 16 serum ß-hCG results, 525 SETs were analysed. Neonatal gender was available for 522 cases. Mean maternal serum ß-hCG levels were similar, 347 ± 191 IU/L in the male newborn group and 371 ± 200 IU/L in the female group. The difference between ß-hCG levels remained insignificant after adjusting for confounding variables. Early maternal ß-hCG levels after embryo transfers did not represent SRGD in our study.

The association between depression and emotional and social loneliness in older persons and the influence of social support, cognitive functioning and personality: A cross-sectional study.

PubMed

Peerenboom, L; Collard, R M; Naarding, P; Comijs, H C

2015-08-15

We investigated the association between old age depression and emotional and social loneliness. A cross-sectional study was performed using data from the Netherlands Study of Depression in Older Persons (NESDO). A total of 341 participants diagnosed with a depressive disorder, and 125 non-depressed participants were included. Depression diagnosis was confirmed with the Composite International Diagnostic Interview. Emotional and social loneliness were assessed using the De Jong Gierveld Loneliness Scale. Socio-demographic variables, social support variables, depression characteristics (Inventory of Depressive Symptoms), cognitive functioning (Mini Mental State Examination) and personality factors (the NEO- Five Factor Inventory and the Pearlin Mastery Scale) were considered as possible explanatory factors or confounders. (Multiple) logistic regression analyses were performed. Depression was strongly associated with emotional loneliness, but not with social loneliness. A higher sense of neuroticism and lower sense of mastery were the most important explanatory factors. Also, we found several other explanatory and confounding factors in the association of depression and emotional loneliness; a lower sense of extraversion and higher severity of depression. We performed a cross-sectional observational study. Therefore we cannot add evidence in regard to causation; whether depression leads to loneliness or vice versa. Depression in older persons is strongly associated with emotional loneliness but not with social loneliness. Several personality traits and the severity of depression are important in regard to the association of depression and emotional loneliness. It is important to develop interventions in which both can be treated. Copyright © 2015 Elsevier B.V. All rights reserved.

Engaging Community College Students Using an Engineering Learning Community

NASA Astrophysics Data System (ADS)

Maccariella, James, Jr.

The study investigated whether community college engineering student success was tied to a learning community. Three separate data collection sources were utilized: surveys, interviews, and existing student records. Mann-Whitney tests were used to assess survey data, independent t-tests were used to examine pre-test data, and independent t-tests, analyses of covariance (ANCOVA), chi-square tests, and logistic regression were used to examine post-test data. The study found students that participated in the Engineering TLC program experienced a significant improvement in grade point values for one of the three post-test courses studied. In addition, the analysis revealed the odds of fall-to-spring retention were 5.02 times higher for students that participated in the Engineering TLC program, and the odds of graduating or transferring were 4.9 times higher for students that participated in the Engineering TLC program. However, when confounding variables were considered in the study (engineering major, age, Pell Grant participation, gender, ethnicity, and full-time/part-time status), the analyses revealed no significant relationship between participation in the Engineering TLC program and course success, fall-to-spring retention, and graduation/transfer. Thus, the confounding variables provided alternative explanations for results. The Engineering TLC program was also found to be effective in providing mentoring opportunities, engagement and motivation opportunities, improved self confidence, and a sense of community. It is believed the Engineering TLC program can serve as a model for other community college engineering programs, by striving to build a supportive environment, and provide guidance and encouragement throughout an engineering student's program of study.

Gender differences in factors associated with suicidal ideation and depressive symptoms among middle-aged workers in Japan.

PubMed

Sugawara, Norio; Yasui-Furukori, Norio; Sasaki, Giro; Tanaka, Osamu; Umeda, Takashi; Takahashi, Ippei; Danjo, Kazuma; Matsuzaka, Masashi; Kaneko, Sunao; Nakaji, Shigeyuki

2013-01-01

The purpose of this study was to assess middle-aged Japanese workers for possible gender differences in the risk factors associated with depressive symptoms and suicidal ideation. 5,878 workers (40-60 yr of age) (3,631 males and 2,247 females) were recruited from randomly selected companies in northern Japan. Demographic and lifestyle factors, suicidal ideation rate, and the data for the Brief Job Stress Questionnaire (BJSQ) and the Center for Epidemiologic Studies for Depression scale (CES-D) were obtained from the self-report questionnaires. After adjusting for possible confounding variables, marital status, absent of stress reduction technique and low job compatibility were significant independent risk factors for suicidal ideation among males. In females, marital status, feeling of insufficient sleep and absence of stress reduction techniques were significant independent risk factors after adjusting for all variables. Under the same adjustments, temporary employment also showed a protective effect against female suicidal ideation. In conclusion, our results suggest that factors related to suicidal ideation differed by gender. Different approaches for each gender might be useful in the development of suicide prevention programs. However, interpretation of work-related effects, such as temporary employment, interpersonal conflict and transportation industry, was hampered by lack of data concerning personal income, working hours and organizational commitment. Additional studies are needed to examine the longitudinal relationships between the risk factors associated with suicidal ideation and depressive symptoms.

Neuropsychological functioning in older people with type 2 diabetes: the effect of controlling for confounding factors.

PubMed

Asimakopoulou, K G; Hampson, S E; Morrish, N J

2002-04-01

Neuropsychological functioning was examined in a group of 33 older (mean age 62.40 +/- 9.62 years) people with Type 2 diabetes (Group 1) and 33 non-diabetic participants matched with Group 1 on age, sex, premorbid intelligence and presence of hypertension and cardio/cerebrovascular conditions (Group 2). Data statistically corrected for confounding factors obtained from the diabetic group were compared with the matched control group. The results suggested small cognitive deficits in diabetic people's verbal memory and mental flexibility (Logical Memory A and SS7). No differences were seen between the two samples in simple and complex visuomotor attention, sustained complex visual attention, attention efficiency, mental double tracking, implicit memory, and self-reported memory problems. These findings indicate minimal cognitive impairment in relatively uncomplicated Type 2 diabetes and demonstrate the importance of control and matching for confounding factors.

Elevated C-reactive Protein Levels in Women with Bipolar Disorder may be Explained by a History of Childhood Trauma, Especially Sexual Abuse, Body Mass Index and Age.

PubMed

Moraes, Juliana Brum; Maes, Michael; Barbosa, Decio Sabbatini; Ferrari, Thais Zagabria; Uehara, Marcela Keikko Spagolla; Carvalho, Andre F; Nunes, Sandra Odebrecht Vargas

2017-01-01

To evaluate whether increased levels of high-sensitivity C- reactive protein (hs-CRP) observed in individuals with bipolar disorder (BD) compared to healthy controls (HCs) could be influenced by a previous exposure to early life stress (ELS) independently from other explanatory or background variables, including age, body mass index (BMI), and the presence of cooccurring mental disorders. In this case-control study, we included 142 healthy controls and 92 bipolar I and II patients. The Childhood Trauma Questionnaire was administered in a subset of 30 female patients with BD and 31 female HCs, and plasma hs-CRP was measured in all subjects. Multivariable models adjusted the data for the possible confounding variables. Serum hs-CRP levels were significantly higher in patients with BD compared to HCs. However, after controlling for BMI, these differences were no longer significant. Around 55% of the variance in hs-CRP was explained by cumulative and independent effects of age, BMI and childhood trauma, especially sexual abuse. Our results show that increased hs-CRP levels in BD patients are more related to childhood trauma, especially sexual abuse, age and BMI than to a diagnosis of BD per se. These data suggest that peripheral inflammation may underpin the well-known detrimental effects of childhood maltreatment and obesity in the course of BD. Hs-CRP data are difficult to interpret if they are not adjusted for effects of BMI and age. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Using instrumental variables to disentangle treatment and placebo effects in blinded and unblinded randomized clinical trials influenced by unmeasured confounders

NASA Astrophysics Data System (ADS)

Chaibub Neto, Elias

2016-11-01

Clinical trials traditionally employ blinding as a design mechanism to reduce the influence of placebo effects. In practice, however, it can be difficult or impossible to blind study participants and unblinded trials are common in medical research. Here we show how instrumental variables can be used to quantify and disentangle treatment and placebo effects in randomized clinical trials comparing control and active treatments in the presence of confounders. The key idea is to use randomization to separately manipulate treatment assignment and psychological encouragement conversations/interactions that increase the participants’ desire for improved symptoms. The proposed approach is able to improve the estimation of treatment effects in blinded studies and, most importantly, opens the doors to account for placebo effects in unblinded trials.

The contribution of smoking to socioeconomic differentials in mortality: results from the Melbourne Collaborative Cohort Study, Australia

PubMed Central

Siahpush, Mohammad; English, Dallas; Powles, John

2006-01-01

Objective To assess the contribution of smoking to the inverse association of mortality with years of formal education in men in Australia. Design Data were obtained from a prospective cohort study that included 17 049 men in Melbourne recruited from 1990 to 1994, most of whom were aged between 40 and 69 years at baseline. The outcome measured was all‐cause mortality. The contribution of smoking to socioeconomic status differentials was estimated by including smoking as a variable in a Cox's proportional hazards model that also included education and other potential confounding variables. Results In men, the association between education and mortality was attenuated after adjustment for smoking, and the aetiological fraction for low levels of education was reduced from 16.5% to 10.6%. Conclusions In men, smoking contributes substantially to socioeconomic differentials in mortality. Effective policies and interventions that target smoking among socially disadvantaged groups may substantially reduce socioeconomic differentials in health. PMID:17108305

The role of sex and body weight on the metabolic effects of high-fat diet in C57BL/6N mice.

PubMed

Ingvorsen, C; Karp, N A; Lelliott, C J

2017-04-10

Metabolic disorders are commonly investigated using knockout and transgenic mouse models on the C57BL/6N genetic background due to its genetic susceptibility to the deleterious metabolic effects of high-fat diet (HFD). There is growing awareness of the need to consider sex in disease progression, but limited attention has been paid to sexual dimorphism in mouse models and its impact in metabolic phenotypes. We assessed the effect of HFD and the impact of sex on metabolic variables in this strain. We generated a reference data set encompassing glucose tolerance, body composition and plasma chemistry data from 586 C57BL/6N mice fed a standard chow and 733 fed a HFD collected as part of a high-throughput phenotyping pipeline. Linear mixed model regression analysis was used in a dual analysis to assess the effect of HFD as an absolute change in phenotype, but also as a relative change accounting for the potential confounding effect of body weight. HFD had a significant impact on all variables tested with an average absolute effect size of 29%. For the majority of variables (78%), the treatment effect was modified by sex and this was dominated by male-specific or a male stronger effect. On average, there was a 13.2% difference in the effect size between the male and female mice for sexually dimorphic variables. HFD led to a significant body weight phenotype (24% increase), which acts as a confounding effect on the other analysed variables. For 79% of the variables, body weight was found to be a significant source of variation, but even after accounting for this confounding effect, similar HFD-induced phenotypic changes were found to when not accounting for weight. HFD and sex are powerful modifiers of metabolic parameters in C57BL/6N mice. We also demonstrate the value of considering body size as a covariate to obtain a richer understanding of metabolic phenotypes.

Identification of confounders in the assessment of the relationship between lead exposure and child development.

PubMed

Tong, I S; Lu, Y

2001-01-01

To explore the best approach to identify and adjust for confounders in epidemiologic practice. In the Port Pirie cohort study, the selection of covariates was based on both a priori and an empirical consideration. In an assessment of the relationship between exposure to environmental lead and child development, change-in-estimate (CE) and significance testing (ST) criteria were compared in identifying potential confounders. The Pearson correlation coefficients were used to evaluate the potential for collinearity between pairs of major quantitative covariates. In multivariate analyses, the effects of confounding factors were assessed with multiple linear regression models. The nature and number of covariates selected varied with different confounder selection criteria and different cutoffs. Four covariates (i.e., quality of home environment, socioeconomic status (SES), maternal intelligence, and parental smoking behaviour) met the conventional CE criterion (> or =10%), whereas 14 variables met the ST criterion (p < or = 0.25). However, the magnitude of the relationship between blood lead concentration and children's IQ differed slightly after adjustment for confounding, using either the CE (partial regression coefficient: -4.4; 95% confidence interval (CI): -0.5 to -8.3) or ST criterion (-4.3; 95% CI: -0.2 to -8.4). Identification and selection of confounding factors need to be viewed cautiously in epidemiologic studies. Either the CE (e.g., > or = 10%) or ST (e.g., p < or = 0.25) criterion may be implemented in identification of a potential confounder if a study sample is sufficiently large, and both the methods are subject to arbitrariness of selecting a cut-off point. In this study, the CE criterion (i.e., > or = 10%) appears to be more stringent than the ST method (i.e., p < or = 0.25) in the identification of confounders. However, the ST rule cannot be used to determine the trueness of confounding because it cannot reflect the causal relationship between the confounder and outcome. This study shows the complexities one can expect to encounter in the identification of and adjustment for confounders.

Can statistic adjustment of OR minimize the potential confounding bias for meta-analysis of case-control study? A secondary data analysis.

PubMed

Liu, Tianyi; Nie, Xiaolu; Wu, Zehao; Zhang, Ying; Feng, Guoshuang; Cai, Siyu; Lv, Yaqi; Peng, Xiaoxia

2017-12-29

Different confounder adjustment strategies were used to estimate odds ratios (ORs) in case-control study, i.e. how many confounders original studies adjusted and what the variables are. This secondary data analysis is aimed to detect whether there are potential biases caused by difference of confounding factor adjustment strategies in case-control study, and whether such bias would impact the summary effect size of meta-analysis. We included all meta-analyses that focused on the association between breast cancer and passive smoking among non-smoking women, as well as each original case-control studies included in these meta-analyses. The relative deviations (RDs) of each original study were calculated to detect how magnitude the adjustment would impact the estimation of ORs, compared with crude ORs. At the same time, a scatter diagram was sketched to describe the distribution of adjusted ORs with different number of adjusted confounders. Substantial inconsistency existed in meta-analysis of case-control studies, which would influence the precision of the summary effect size. First, mixed unadjusted and adjusted ORs were used to combine individual OR in majority of meta-analysis. Second, original studies with different adjustment strategies of confounders were combined, i.e. the number of adjusted confounders and different factors being adjusted in each original study. Third, adjustment did not make the effect size of original studies trend to constringency, which suggested that model fitting might have failed to correct the systematic error caused by confounding. The heterogeneity of confounder adjustment strategies in case-control studies may lead to further bias for summary effect size in meta-analyses, especially for weak or medium associations so that the direction of causal inference would be even reversed. Therefore, further methodological researches are needed, referring to the assessment of confounder adjustment strategies, as well as how to take this kind of bias into consideration when drawing conclusion based on summary estimation of meta-analyses.

Incidence of workers compensation indemnity claims across socio-demographic and job characteristics.

PubMed

Du, Juan; Leigh, J Paul

2011-10-01

We hypothesized that low socioeconomic status, employer-provided health insurance, low wages, and overtime were predictors of reporting workers compensation indemnity claims. We also tested for gender and race disparities. Responses from 17,190 (person-years) Americans participating in the Panel Study of Income Dynamics, 1997-2005, were analyzed with logistic regressions. The dependent variable indicated whether the subject collected benefits from a claim. Odds ratios for men and African-Americans were relatively large and strongly significant predictors of claims; significance for Hispanics was moderate and confounded by education. Odds ratios for variables measuring education were the largest for all statistically significant covariates. Neither low wages nor employer-provided health insurance was a consistent predictor. Due to confounding from the "not salaried" variable, overtime was not a consistently significant predictor. Few studies use nationally representative longitudinal data to consider which demographic and job characteristics predict reporting workers compensation indemnity cases. This study did and tested some common hypotheses about predictors. Copyright © 2011 Wiley-Liss, Inc.

Doubly robust matching estimators for high dimensional confounding adjustment.

PubMed

Antonelli, Joseph; Cefalu, Matthew; Palmer, Nathan; Agniel, Denis

2018-05-11

Valid estimation of treatment effects from observational data requires proper control of confounding. If the number of covariates is large relative to the number of observations, then controlling for all available covariates is infeasible. In cases where a sparsity condition holds, variable selection or penalization can reduce the dimension of the covariate space in a manner that allows for valid estimation of treatment effects. In this article, we propose matching on both the estimated propensity score and the estimated prognostic scores when the number of covariates is large relative to the number of observations. We derive asymptotic results for the matching estimator and show that it is doubly robust in the sense that only one of the two score models need be correct to obtain a consistent estimator. We show via simulation its effectiveness in controlling for confounding and highlight its potential to address nonlinear confounding. Finally, we apply the proposed procedure to analyze the effect of gender on prescription opioid use using insurance claims data. © 2018, The International Biometric Society.

Effect decomposition in the presence of an exposure-induced mediator-outcome confounder

PubMed Central

VanderWeele, Tyler J.; Vansteelandt, Stijn; Robins, James M.

2014-01-01

Methods from causal mediation analysis have generalized the traditional approach to direct and indirect effects in the epidemiologic and social science literature by allowing for interaction and non-linearities. However, the methods from the causal inference literature have themselves been subject to a major limitation in that the so-called natural direct and indirect effects that are employed are not identified from data whenever there is a variable that is affected by the exposure, which also confounds the relationship between the mediator and the outcome. In this paper we describe three alternative approaches to effect decomposition that give quantities that can be interpreted as direct and indirect effects, and that can be identified from data even in the presence of an exposure-induced mediator-outcome confounder. We describe a simple weighting-based estimation method for each of these three approaches, illustrated with data from perinatal epidemiology. The methods described here can shed insight into pathways and questions of mediation even when an exposure-induced mediator-outcome confounder is present. PMID:24487213

Influence of lifestyle and genetic variants in the aldo-keto reductase 1C3 rs12529 polymorphism in high-risk prostate cancer detection variability assessed between US and New Zealand cohorts

PubMed Central

Ambs, Stefan; Tang, Wei; Zhu, Shuotun; Dorsey, Tiffany H.; Goudie, Megan; Masters, Jonathan G.; Ferguson, Lynnette R.

2018-01-01

Introduction The prostate-specific antigen (PSA) based prostate cancer (PC) screening is currently being debated. The current assessment is to understand the variability of detecting high-risk PC in a NZ cohort in comparison to a US cohort with better PSA screening facilities. Aldo-keto reductase 1C3 (AKR1C3) is known for multiple functions with a potential to regulate subsequent PSA levels. Therefore, we wish to understand the influence of tobacco smoking and the AKR1C3 rs12529 gene polymorphism in this variability. Method NZ cohort (n = 376) consisted of 94% Caucasians while the US cohort consisted of African Americans (AA), n = 202, and European Americans (EA), n = 232. PSA level, PC grade and stage at diagnosis were collected from hospital databases for assigning high-risk PC status. Tobacco smoking status and the AKR1C3 rs12529 SNP genotype were considered as confounding variables. Variation of the cumulative % high-risk PC (outcome variable) with increasing PSA intervals (exposure factor) was compared between the cohorts using the Kolmogorov-Smirnov test. Comparisons were carried out with and without stratifications made using confounding variables. Results NZ cohort has been diagnosed at a significantly higher mean age (66.67± (8.08) y) compared to both AA (62.65±8.17y) and EA (64.83+8.56y); median PSA (NZ 8.90ng/ml compared to AA 6.86ng/ml and EA 5.80ng/ml); and Gleason sum (NZ (7) compared EA (6)) (p<0.05). The cumulative % high-risk PC detection shows NZ cohort with a significantly lower diagnosis rates at PSA levels between >6 - <10ng/ml compared to both US groups (p<0.05). These were further compounded significantly by smoking status and genetics. Conclusions High-risk PCs recorded at higher PSA levels in NZ could be due to factors including lower levels of PSA screening and subsequent specialist referrals for biopsies. These consequences could be pronounced among NZ ever smokers carrying the AKR1C3 rs12529 G alleles making them a group that requires increased PSA screening attention. PMID:29920533

Prediction of Success in External Cephalic Version under Tocolysis: Still a Challenge.

PubMed

Vaz de Macedo, Carolina; Clode, Nuno; Mendes da Graça, Luís

2015-01-01

External cephalic version is a procedure of fetal rotation to a cephalic presentation through manoeuvres applied to the maternal abdomen. There are several prognostic factors described in literature for external cephalic version success and prediction scores have been proposed, but their true implication in clinical practice is controversial. We aim to identify possible factors that could contribute to the success of an external cephalic version attempt in our population. We retrospectively examined 207 consecutive external cephalic version attempts under tocolysis conducted between January 1997 and July 2012. We consulted the department's database for the following variables: race, age, parity, maternal body mass index, gestational age, estimated fetal weight, breech category, placental location and amniotic fluid index. We performed descriptive and analytical statistics for each variable and binary logistic regression. External cephalic version was successful in 46.9% of cases (97/207). None of the included variables was associated with the outcome of external cephalic version attempts after adjustment for confounding factors. We present a success rate similar to what has been previously described in literature. However, in contrast to previous authors, we could not associate any of the analysed variables with success of the external cephalic version attempt. We believe this discrepancy is partly related to the type of statistical analysis performed. Even though there are numerous prognostic factors identified for the success in external cephalic version, care must be taken when counselling and selecting patients for this procedure. The data obtained suggests that external cephalic version should continue being offered to all eligible patients regardless of prognostic factors for success.

PHOSPHATE BINDER USE AND MORTALITY AMONG HEMODIALYSIS PATIENTS IN THE DOPPS: EVALUATION OF POSSIBLE CONFOUNDING BY NUTRITIONAL STATUS

PubMed Central

Lopes, Antonio Alberto; Tong, Lin; Thumma, Jyothi; Li, Yun; Fuller, Douglas S.; Morgenstern, Hal; Bommer, Jürgen; Kerr, Peter G; Tentori, Francesca; Akiba, Takashi; Gillespie, Brenda; Robinson, Bruce M.; Port, Friedrich K; Pisoni, Ronald L.

2014-01-01

Background Poor nutritional status and both hyperphosphatemia and hypophosphatemia are associated with increased mortality in maintenance hemodialysis (MHD) patients. We assessed associations of PB prescription with survival and indicators of nutritional status among (MHD) patients. Study Design Prospective cohort study (DOPPS) 1996 to 2008. Setting and Participants 23,898 MHD patients at 923 facilities in 12 countries. Predictors Patient-level PB prescription; and case-mix-adjusted facility percentage PB prescription using an instrumental-variable analysis. Outcome All-cause mortality. Results Overall, 88% of patients were prescribed PBs. The distributions of age, comorbidities and other characteristics showed small differences between facilities with higher and lower percentage PB prescription. Patient-level PB prescription was strongly associated at baseline with indicators of better nutrition, i.e., higher serum creatinine, albumin, normalized protein-catabolic rate, BMI and absence of cachectic appearance. Overall, patients prescribed PBs displayed 25% lower mortality (hazard ratio [HR] = 0.75, 95% confidence interval [CI] = 0.68–0.83) when adjusted for serum phosphorus and other covariates; further adjustment for nutritional indicators attenuated this association (HR = 0.88, 95% CI = 0.80–0.97). This inverse association, however, was observed only for patients with serum phosphorus ≥3.5mg/dL. In the instrumental-variable analysis, case-mix-adjusted facility percentage PB prescription (range: 23–100%) was positively associated with better nutritional status and inversely associated with mortality (HR for 10% more PB = 0.93, 95% CI = 0.89–0.96). Further adjustment for nutritional indicators reduced this association to HR = 0.95 (95% CI = 0.92–0.99). Limitations Results were based on PB prescription; PB and nutritional data were cross-sectional; dietary restriction was not assessed; observational design limits causal inference due to possible residual confounding. Conclusions Longer survival and better nutritional status were observed for MHD patients prescribed PBs and in facilities with greater percentage PB prescription. Understanding the mechanisms for explaining this effect and ruling out possible residual confounding require additional research. PMID:22385781

Relative importance of climatic, geographic and socio-economic determinants of malaria in Malawi

PubMed Central

2013-01-01

Background Malaria transmission is influenced by variations in meteorological conditions, which impact the biology of the parasite and its vector, but also socio-economic conditions, such as levels of urbanization, poverty and education, which impact human vulnerability and vector habitat. The many potential drivers of malaria, both extrinsic, such as climate, and intrinsic, such as population immunity are often difficult to disentangle. This presents a challenge for the modelling of malaria risk in space and time. Methods A statistical mixed model framework is proposed to model malaria risk at the district level in Malawi, using an age-stratified spatio-temporal dataset of malaria cases from July 2004 to June 2011. Several climatic, geographic and socio-economic factors thought to influence malaria incidence were tested in an exploratory model. In order to account for the unobserved confounding factors that influence malaria, which are not accounted for using measured covariates, a generalized linear mixed model was adopted, which included structured and unstructured spatial and temporal random effects. A hierarchical Bayesian framework using Markov chain Monte Carlo simulation was used for model fitting and prediction. Results Using a stepwise model selection procedure, several explanatory variables were identified to have significant associations with malaria including climatic, cartographic and socio-economic data. Once intervention variations, unobserved confounding factors and spatial correlation were considered in a Bayesian framework, a final model emerged with statistically significant predictor variables limited to average precipitation (quadratic relation) and average temperature during the three months previous to the month of interest. Conclusions When modelling malaria risk in Malawi it is important to account for spatial and temporal heterogeneity and correlation between districts. Once observed and unobserved confounding factors are allowed for, precipitation and temperature in the months prior to the malaria season of interest are found to significantly determine spatial and temporal variations of malaria incidence. Climate information was found to improve the estimation of malaria relative risk in 41% of the districts in Malawi, particularly at higher altitudes where transmission is irregular. This highlights the potential value of climate-driven seasonal malaria forecasts. PMID:24228784

Glucose impairment and ghrelin gene variants are associated to cognitive dysfunction.

PubMed

Mora, M; Mansego, M L; Serra-Prat, M; Palomera, E; Boquet, X; Chaves, J F; Puig-Domingo, M

2014-04-01

Cognitive state and brain volume have been related to body mass index, abdominal fat, waist-hip ratio, components of metabolic syndrome (MS) and ghrelin. Genetic variations within the ghrelin gene have been recently associated to MS. The aim of our study was to investigate cognitive state by Mini-Mental State Examination (MMSE) in relation to MS components (ATP-III criteria) and ghrelin gene polymorphisms in dwelling individuals aged ≥70. 280 subjects (137 men/143 women, age 77.03 ± 5.92) from the Mataró Ageing Study were included. Individuals were phenotypically characterized by anthropometric variables, lipids, glucose, blood pressure and MMSE. SNPs -501AC (rs26802), -994CT (rs26312), -604GA (rs27647), M72L (rs696217) and L90G (rs4684677) of the ghrelin gene were studied. Genotypes were determined by polymerase chain reaction and SNapshot minisequencing. 22.1 % had MMSE <24. MMSE <24 was associated with age (p < 0.001), female gender (p = 0.016), low education (p < 0.001) and glucose impairment or diabetes (p = 0.040). MMSE was influenced by obesity, central obesity, MS and glucose impairment. This latter association remained significant after adjustment by gender, age, alcohol, educational level, GDS and ApoE genotype (p = 0.009). Ghrelin SNPs were associated to MMSE: M72L C/A genotype showed lower score than C/C (p = 0.032, after adjusting for confounders 0.049); L90G A/T genotype showed lower score than A/A (p = 0.054, after adjusting 0.005). MMSE <24 was associated to L90G (39.1 % in A/T genotype vs 19.3 % in A/A, p = 0.026, after adjusting for confounders p = 0.002, OR 6.18 CI 1.93-21.75). Glucose impairment and L90G Ghrelin gene variant influence cognitive function in old dwelling individuals participating in the Mataró Ageing Study.

CADDIS Volume 4. Data Analysis: Basic Principles & Issues

EPA Pesticide Factsheets

Use of inferential statistics in causal analysis, introduction to data independence and autocorrelation, methods to identifying and control for confounding variables, references for the Basic Principles section of Data Analysis.

Chronic malnutrition and Trypanosoma cruzi infection in children.

PubMed

de Andrade, A L; Zicker, F

1995-04-01

The distribution of T. cruzi infection overlaps regions with high prevalence of child malnutrition. We examined the possible association between T. cruzi infection and chronic malnutrition. In a cross-sectional survey conducted among 1900 7-12 year-old schoolchildren in 60 village schools in central Brazil, anthropometric measurements (NCHS) taken from 153 children with at least two positive serological tests for antibodies against T. cruzi (IIF, ELISA, IHA) were compared to two age and sex seronegative matched classmates. Information on children's medical history and socio-economic status (SES) were collected from parents of the participants. Seropositive children had a 2.4-fold risk (95% CI 1.4-4.0) of being stunted (z-score < 2.0 of height-for-age) when compared to uninfected children even after adjusting for confounding variables. Being underweight (z-score < -2.0 of weight-for-age) was also statistically associated with seropositivity to T. cruzi (OR = 2.8, 95% CI 1.4-5.6). No statistical evidence of multiplicative interaction between nutritional status and SES was detected. Further studies on nutrition and metabolism are required to look into a possible physiopathological mechanism for this association.

Dietary habits and breast cancer incidence among Seventh-day Adventists.

PubMed

Mills, P K; Beeson, W L; Phillips, R L; Fraser, G E

1989-08-01

Breast cancer incidence was monitored in a cohort of 20,341 California Seventh-day Adventist women who completed a detailed lifestyle questionnaire in 1976, and who were followed for 6 years. There were 215 histologically confirmed primary breast cancer detected among some 115,000 person-years of follow-up. Mean age at diagnosis was 66 years, indicating a primarily postmenopausal case series. Established risk factors for breast cancer showed strong relationships to risk in these data. Age at first live birth, maternal history of breast cancer, age at menopause, educational attainment, and obesity were all significantly related to risk. However, increasing consumption of high fat animal products was not associated with increased risk of breast cancer in a consistent fashion. Nor were childhood and early teenage dietary habits (vegetarian versus nonvegetarian) related to subsequent, adult risk of developing breast cancer. Also, a derived index of percent of calories from animal fat in the adult years was not significantly related to risk. These results persisted after simultaneously controlling for other, potentially confounding variables, utilizing Cox proportional hazard regression models.

Mendelian Randomization.

PubMed

Grover, Sandeep; Del Greco M, Fabiola; Stein, Catherine M; Ziegler, Andreas

2017-01-01

Confounding and reverse causality have prevented us from drawing meaningful clinical interpretation even in well-powered observational studies. Confounding may be attributed to our inability to randomize the exposure variable in observational studies. Mendelian randomization (MR) is one approach to overcome confounding. It utilizes one or more genetic polymorphisms as a proxy for the exposure variable of interest. Polymorphisms are randomly distributed in a population, they are static throughout an individual's lifetime, and may thus help in inferring directionality in exposure-outcome associations. Genome-wide association studies (GWAS) or meta-analyses of GWAS are characterized by large sample sizes and the availability of many single nucleotide polymorphisms (SNPs), making GWAS-based MR an attractive approach. GWAS-based MR comes with specific challenges, including multiple causality. Despite shortcomings, it still remains one of the most powerful techniques for inferring causality.With MR still an evolving concept with complex statistical challenges, the literature is relatively scarce in terms of providing working examples incorporating real datasets. In this chapter, we provide a step-by-step guide for causal inference based on the principles of MR with a real dataset using both individual and summary data from unrelated individuals. We suggest best possible practices and give recommendations based on the current literature.

Maternal age and risk of labor and delivery complications.

PubMed

Cavazos-Rehg, Patricia A; Krauss, Melissa J; Spitznagel, Edward L; Bommarito, Kerry; Madden, Tessa; Olsen, Margaret A; Subramaniam, Harini; Peipert, Jeffrey F; Bierut, Laura Jean

2015-06-01

We utilized an updated nationally representative database to examine associations between maternal age and prevalence of maternal morbidity during complications of labor and delivery. We used hospital inpatient billing data from the 2009 United States Nationwide Inpatient Sample, part of the Healthcare Cost and Utilization Project. To determine whether the likelihood that maternal morbidity during complications of labor and delivery differed among age groups, separate logistic regression models were run for each complication. Age was the main independent variable of interest. In analyses that controlled for demographics and clinical confounders, we found that complications with the highest odds among women, 11-18 years of age, compared to 25-29 year old women, included preterm delivery, chorioamnionitis, endometritis, and mild preeclampsia. Pregnant women who were 15-19 years old had greater odds for severe preeclampsia, eclampsia, postpartum hemorrhage, poor fetal growth, and fetal distress. Pregnant women who were ≥35 years old had greater odds for preterm delivery, hypertension, superimposed preeclampsia, severe preeclampsia, and decreased risk for chorioamnionitis. Older women (≥40 years old) had increased odds for mild preeclampsia, fetal distress, and poor fetal growth. Our findings underscore the need for pregnant women to be aware of the risks associated with extremes of age so that they can watch for signs and symptoms of such complications.

Age versus schooling effects on intelligence development.

PubMed

Cahan, S; Cohen, N

1989-10-01

The effect of formal education, as opposed to chronological age, on intelligence development has suffered from inadequate empirical investigation. Most studies of this issue have relied on natural variation in exposure to school among children of the same age, thus confounding differences in schooling with differences in other intelligence-related variables. This difficulty can be overcome by a quasi-experimental paradigm involving comparison between children who differ in both chronological age and schooling. The present study applies this paradigm to the estimation of the independent effects of age and schooling in grades 5 and 6 on raw scores obtained on a variety of general ability tests. The sample included all students in Jerusalem's Hebrew-language, state-controlled elementary schools. The results unambiguously point to schooling as the major factor underlying the increase of intelligence test scores as a function of age and to the larger effect schooling has on verbal than nonverbal tests. These results contribute to our understanding of the causal model underlying intelligence development and call for reconsideration of the conceptual basis underlying the definition of deviation-IQ scores. Some implications of these results concerning the distinction between intelligence and scholastic achievement, the causal model underlying the development of "crystallized" and "fluid" abilities, and the notion of "culture-fair" tests are discussed.

Clustering Words to Match Conditions: An Algorithm for Stimuli Selection in Factorial Designs

ERIC Educational Resources Information Center

Guasch, Marc; Haro, Juan; Boada, Roger

2017-01-01

With the increasing refinement of language processing models and the new discoveries about which variables can modulate these processes, stimuli selection for experiments with a factorial design is becoming a tough task. Selecting sets of words that differ in one variable, while matching these same words into dozens of other confounding variables…

A review of covariate selection for non-experimental comparative effectiveness research.

PubMed

Sauer, Brian C; Brookhart, M Alan; Roy, Jason; VanderWeele, Tyler

2013-11-01

This paper addresses strategies for selecting variables for adjustment in non-experimental comparative effectiveness research and uses causal graphs to illustrate the causal network that relates treatment to outcome. Variables in the causal network take on multiple structural forms. Adjustment for a common cause pathway between treatment and outcome can remove confounding, whereas adjustment for other structural types may increase bias. For this reason, variable selection would ideally be based on an understanding of the causal network; however, the true causal network is rarely known. Therefore, we describe more practical variable selection approaches based on background knowledge when the causal structure is only partially known. These approaches include adjustment for all observed pretreatment variables thought to have some connection to the outcome, all known risk factors for the outcome, and all direct causes of the treatment or the outcome. Empirical approaches, such as forward and backward selection and automatic high-dimensional proxy adjustment, are also discussed. As there is a continuum between knowing and not knowing the causal, structural relations of variables, we recommend addressing variable selection in a practical way that involves a combination of background knowledge and empirical selection and that uses high-dimensional approaches. This empirical approach can be used to select from a set of a priori variables based on the researcher's knowledge to be included in the final analysis or to identify additional variables for consideration. This more limited use of empirically derived variables may reduce confounding while simultaneously reducing the risk of including variables that may increase bias. Copyright © 2013 John Wiley & Sons, Ltd.

A Review of Covariate Selection for Nonexperimental Comparative Effectiveness Research

PubMed Central

Sauer, Brian C.; Brookhart, Alan; Roy, Jason; Vanderweele, Tyler

2014-01-01

This paper addresses strategies for selecting variables for adjustment in non-experimental comparative effectiveness research (CER), and uses causal graphs to illustrate the causal network that relates treatment to outcome. Variables in the causal network take on multiple structural forms. Adjustment for on a common cause pathway between treatment and outcome can remove confounding, while adjustment for other structural types may increase bias. For this reason variable selection would ideally be based on an understanding of the causal network; however, the true causal network is rarely know. Therefore, we describe more practical variable selection approaches based on background knowledge when the causal structure is only partially known. These approaches include adjustment for all observed pretreatment variables thought to have some connection to the outcome, all known risk factors for the outcome, and all direct causes of the treatment or the outcome. Empirical approaches, such as forward and backward selection and automatic high-dimensional proxy adjustment, are also discussed. As there is a continuum between knowing and not knowing the causal, structural relations of variables, we recommend addressing variable selection in a practical way that involves a combination of background knowledge and empirical selection and that uses the high-dimensional approaches. This empirical approach can be used to select from a set of a priori variables based on the researcher’s knowledge to be included in the final analysis or to identify additional variables for consideration. This more limited use of empirically-derived variables may reduce confounding while simultaneously reducing the risk of including variables that may increase bias. PMID:24006330

An assessment of the possible extent of confounding in epidemiological studies of lung cancer risk among roofers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mundt, D.J.; van Wijngaarden, E.; Mundt, K.A.

2007-07-01

We evaluated the likelihood and extent to which the observed increased risk of lung cancer may be due to confounding (a mixing of effects of multiple exposures) by co-exposure to other potential carcinogens present in roofing or to lifestyle variables. We conducted a review of the epidemiological and industrial hygiene literature of asphalt-exposed workers. Peer-reviewed epidemiological studies of asphalt fumes, related occupational exposures, and confounding factors were identified from MEDLINE (1966 early 2004). Industrial hygiene studies of asphalt workers were identified through MEDLINE, publicly available government documents, and asphalt industry documents. Using well established statistical methods, we quantified the extentmore » to which lung cancer relative risk estimates among roofers reflect confounding from other exposures, using different prevalence and risk scenarios. The relative risk of lung cancer varied from 1.2 to 5.0 in 13 epidemiological studies of roofers; most studies reported a relative risk between 1.2 and 1.4. Smoking, asbestos and coal tar were the most likely confounders, but the prevalence of these factors varied over time. The results of the study indicate that much of the observed risk reported in epidemiological studies of cancer among roofers is well within the range of what may have resulted from confounding by reasonable and expected levels of smoking, asbestos or coal tar. This may be particularly true for those studies that did not adjust for these confounders and where the exposure was defined as employment in the roofing industry. In addition to poorly defined asphalt exposure, uncontrolled confounding cannot reliably be ruled out in studies of lung cancer among asphalt-exposed roofers. Therefore, it is not possible to conclude whether roofers are at increased risk of lung cancer due to asphalt exposure.« less

External adjustment sensitivity analysis for unmeasured confounding: an application to coronary stent outcomes, Pennsylvania 2004-2008.

PubMed

Huesch, Marco D

2013-06-01

Assessing the real-world comparative effectiveness of common interventions is challenged by unmeasured confounding. To determine whether the mortality benefit shown for drug-eluting stents (DES) over bare metal stents (BMS) in observational studies persists after controls for/tests for confounding. Retrospective observational study involving 38,019 patients, 65 years or older admitted for an index percutaneous coronary intervention receiving DES or BMS in Pennsylvania in 2004-2005 followed up for death through 3 years. Analysis was at the patient level. Mortality was analyzed with Cox proportional hazards models allowing for stratification by disease severity or DES use propensity, accounting for clustering of patients. Instrumental variables analysis used lagged physician stent usage to proxy for the focal stent type decision. A method originating in work by Cornfield and others in 1954 and popularized by Greenland in 1996 was used to assess robustness to confounding. DES was associated with a significantly lower adjusted risk of death at 3 years in Cox and in instrumented analyses. An implausibly strong hypothetical unobserved confounder would be required to fully explain these results. Confounding by indication can bias observational studies. No strong evidence of such selection biases was found in the reduced risk of death among elderly patients receiving DES instead of BMS in a Pennsylvanian state-wide population. © Health Research and Educational Trust.

Why Do Thin People Have Elevated All-Cause Mortality? Evidence on Confounding and Reverse Causality in the Association of Adiposity and COPD from the British Women’s Heart and Health Study

PubMed Central

Dale, Caroline; Nüesch, Eveline; Prieto-Merino, David; Choi, Minkyoung; Amuzu, Antoinette; Ebrahim, Shah; Casas, Juan P.; Davey-Smith, George

2015-01-01

Low adiposity has been linked to elevated mortality from several causes including respiratory disease. However, this could arise from confounding or reverse causality. We explore the association between two measures of adiposity (BMI and WHR) with COPD in the British Women’s Heart and Health Study including a detailed assessment of the potential for confounding and reverse causality for each adiposity measure. Low BMI was found to be associated with increased COPD risk while low WHR was not (OR = 2.2; 95% CI 1.3 – 3.1 versus OR = 1.2; 95% CI 0.7 – 1.6). Potential confounding variables (e.g. smoking) and markers of ill-health (e.g. unintentional weight loss) were found to be higher in low BMI but not in low WHR. Women with low BMI have a detrimental profile across a broad range of health markers compared to women with low WHR, and women with low WHR do not appear to have an elevated COPD risk, lending support to the hypothesis that WHR is a less confounded measure of adiposity than BMI. Low adiposity does not in itself appear to increase the risk of respiratory disease, and the apparent adverse consequences of low BMI may be due to reverse causation and confounding. PMID:25884834

Fusing Data Mining, Machine Learning and Traditional Statistics to Detect Biomarkers Associated with Depression

PubMed Central

Dipnall, Joanna F.

2016-01-01

Background Atheoretical large-scale data mining techniques using machine learning algorithms have promise in the analysis of large epidemiological datasets. This study illustrates the use of a hybrid methodology for variable selection that took account of missing data and complex survey design to identify key biomarkers associated with depression from a large epidemiological study. Methods The study used a three-step methodology amalgamating multiple imputation, a machine learning boosted regression algorithm and logistic regression, to identify key biomarkers associated with depression in the National Health and Nutrition Examination Study (2009–2010). Depression was measured using the Patient Health Questionnaire-9 and 67 biomarkers were analysed. Covariates in this study included gender, age, race, smoking, food security, Poverty Income Ratio, Body Mass Index, physical activity, alcohol use, medical conditions and medications. The final imputed weighted multiple logistic regression model included possible confounders and moderators. Results After the creation of 20 imputation data sets from multiple chained regression sequences, machine learning boosted regression initially identified 21 biomarkers associated with depression. Using traditional logistic regression methods, including controlling for possible confounders and moderators, a final set of three biomarkers were selected. The final three biomarkers from the novel hybrid variable selection methodology were red cell distribution width (OR 1.15; 95% CI 1.01, 1.30), serum glucose (OR 1.01; 95% CI 1.00, 1.01) and total bilirubin (OR 0.12; 95% CI 0.05, 0.28). Significant interactions were found between total bilirubin with Mexican American/Hispanic group (p = 0.016), and current smokers (p<0.001). Conclusion The systematic use of a hybrid methodology for variable selection, fusing data mining techniques using a machine learning algorithm with traditional statistical modelling, accounted for missing data and complex survey sampling methodology and was demonstrated to be a useful tool for detecting three biomarkers associated with depression for future hypothesis generation: red cell distribution width, serum glucose and total bilirubin. PMID:26848571

Bilingualism and Cognitive Reserve: A Critical Overview and a Plea for Methodological Innovations

PubMed Central

Calvo, Noelia; García, Adolfo M.; Manoiloff, Laura; Ibáñez, Agustín

2016-01-01

The decline of cognitive skills throughout healthy or pathological aging can be slowed down by experiences which foster cognitive reserve (CR). Recently, some studies on Alzheimer's disease have suggested that CR may be enhanced by life-long bilingualism. However, the evidence is inconsistent and largely based on retrospective approaches featuring several methodological weaknesses. Some studies demonstrated at least 4 years of delay in dementia symptoms, while others did not find such an effect. Moreover, various methodological aspects vary from study to study. The present paper addresses contradictory findings, identifies possible lurking variables, and outlines methodological alternatives thereof. First, we characterize possible confounding factors that may have influenced extant results. Our focus is on the criteria to establish bilingualism, differences in sample design, the instruments used to examine cognitive skills, and the role of variables known to modulate life-long cognition. Second, we propose that these limitations could be largely circumvented through experimental approaches. Proficiency in the non-native language can be successfully assessed by combining subjective and objective measures; confounding variables which have been distinctively associated with certain bilingual groups (e.g., alcoholism, sleep disorders) can be targeted through relevant instruments; and cognitive status might be better tapped via robust cognitive screenings and executive batteries. Moreover, future research should incorporate tasks yielding predictable patterns of contrastive performance between bilinguals and monolinguals. Crucially, these include instruments which reveal bilingual disadvantages in vocabulary, null effects in working memory, and advantages in inhibitory control and other executive functions. Finally, paradigms tapping proactive interference (which assess the disruptive effect of long-term memory on newly learned information) could also offer useful data, since this phenomenon seems to be better managed by bilinguals and it becomes conspicuous in early stages of dementia. Such considerations may shed light not just on the relationship between bilingualism and CR, but also on more general mechanisms of cognitive compensation. PMID:26793100

Anthropometric measures change and quality of life in elderly people: a longitudinal population-based study in Southern Brazil.

PubMed

Tessari, Ana Aparecida; Giehl, Maruí Weber Corseuil; Schneider, Ione Jayce Ceola; González-Chica, David Alejandro

2016-12-01

To analyze the effects of anthropometric measures change on quality of life (QoL) in elderly, using measured anthropometric data on body mass index (BMI) and waist circumference (WC). Population-based cohort study investigating a sample of elderly (≥60) assessed in 2009 (n = 1705) and followed up in 2013 (n = 1197). QoL was evaluated in 2013 using the CASP-19. Variables evaluated as exposure including BMI and WC in 2009 (both standardized), categories of anthropometric measures change from 2009 to 2013 (excess weight = BMI ≥ 25.0 kg/m 2 ; large WC = top quartile), and the absolute BMI and WC change in same period. Multivariate linear regressions adjusted for possible confounding factors and mediators were used. Both BMI and WC at baseline were associated with lower QoL scores, even after adjustment for confounding variables (β BMI  = -0.9; 95 % CI -1.5; -0.3 and β WC  = -1.0; 95 % CI -1.7; -0.4). Additionally, QoL scores were lower among elderly with excess weight (β = -1.4; 95 % CI -2.9; 0.0) or large WC (β = -3.3; 95 % CI -5.2; -1.4) in both waves than among those whose BMI and WC were always normal, but changes in anthropometric measures did not affect QoL. The presence of chronic diseases was a partial mediator of these associations, especially for effects of BMI change. Anthropometric measures change treated as a continuous variable was not associated with QoL. Having excess weight and large WC in both waves was associated with lower QoL scores in elderly, but changing the anthropometric measures did not affect this outcome. Maintaining weight and WC within normal limits during aging can help to preserve QoL.

Fusing Data Mining, Machine Learning and Traditional Statistics to Detect Biomarkers Associated with Depression.

PubMed

Dipnall, Joanna F; Pasco, Julie A; Berk, Michael; Williams, Lana J; Dodd, Seetal; Jacka, Felice N; Meyer, Denny

2016-01-01

Atheoretical large-scale data mining techniques using machine learning algorithms have promise in the analysis of large epidemiological datasets. This study illustrates the use of a hybrid methodology for variable selection that took account of missing data and complex survey design to identify key biomarkers associated with depression from a large epidemiological study. The study used a three-step methodology amalgamating multiple imputation, a machine learning boosted regression algorithm and logistic regression, to identify key biomarkers associated with depression in the National Health and Nutrition Examination Study (2009-2010). Depression was measured using the Patient Health Questionnaire-9 and 67 biomarkers were analysed. Covariates in this study included gender, age, race, smoking, food security, Poverty Income Ratio, Body Mass Index, physical activity, alcohol use, medical conditions and medications. The final imputed weighted multiple logistic regression model included possible confounders and moderators. After the creation of 20 imputation data sets from multiple chained regression sequences, machine learning boosted regression initially identified 21 biomarkers associated with depression. Using traditional logistic regression methods, including controlling for possible confounders and moderators, a final set of three biomarkers were selected. The final three biomarkers from the novel hybrid variable selection methodology were red cell distribution width (OR 1.15; 95% CI 1.01, 1.30), serum glucose (OR 1.01; 95% CI 1.00, 1.01) and total bilirubin (OR 0.12; 95% CI 0.05, 0.28). Significant interactions were found between total bilirubin with Mexican American/Hispanic group (p = 0.016), and current smokers (p<0.001). The systematic use of a hybrid methodology for variable selection, fusing data mining techniques using a machine learning algorithm with traditional statistical modelling, accounted for missing data and complex survey sampling methodology and was demonstrated to be a useful tool for detecting three biomarkers associated with depression for future hypothesis generation: red cell distribution width, serum glucose and total bilirubin.

Bilingualism and Cognitive Reserve: A Critical Overview and a Plea for Methodological Innovations.

PubMed

Calvo, Noelia; García, Adolfo M; Manoiloff, Laura; Ibáñez, Agustín

2015-01-01

The decline of cognitive skills throughout healthy or pathological aging can be slowed down by experiences which foster cognitive reserve (CR). Recently, some studies on Alzheimer's disease have suggested that CR may be enhanced by life-long bilingualism. However, the evidence is inconsistent and largely based on retrospective approaches featuring several methodological weaknesses. Some studies demonstrated at least 4 years of delay in dementia symptoms, while others did not find such an effect. Moreover, various methodological aspects vary from study to study. The present paper addresses contradictory findings, identifies possible lurking variables, and outlines methodological alternatives thereof. First, we characterize possible confounding factors that may have influenced extant results. Our focus is on the criteria to establish bilingualism, differences in sample design, the instruments used to examine cognitive skills, and the role of variables known to modulate life-long cognition. Second, we propose that these limitations could be largely circumvented through experimental approaches. Proficiency in the non-native language can be successfully assessed by combining subjective and objective measures; confounding variables which have been distinctively associated with certain bilingual groups (e.g., alcoholism, sleep disorders) can be targeted through relevant instruments; and cognitive status might be better tapped via robust cognitive screenings and executive batteries. Moreover, future research should incorporate tasks yielding predictable patterns of contrastive performance between bilinguals and monolinguals. Crucially, these include instruments which reveal bilingual disadvantages in vocabulary, null effects in working memory, and advantages in inhibitory control and other executive functions. Finally, paradigms tapping proactive interference (which assess the disruptive effect of long-term memory on newly learned information) could also offer useful data, since this phenomenon seems to be better managed by bilinguals and it becomes conspicuous in early stages of dementia. Such considerations may shed light not just on the relationship between bilingualism and CR, but also on more general mechanisms of cognitive compensation.

Correlates of osteoporosis among Jewish and Arab women aged 45-74 in Israel: national women's health interview survey.

PubMed

Nitzan-Kaluski, Dorit; Chinich, Ayelet; Ifrah, Anneke; Merom, Dafna; Green, Manfred S

2003-01-01

To determine the prevalence and correlates of osteoporosis among middle-aged and elderly Jewish and Arab women in Israel. A cross-sectional study on a random sample of Israeli women, carried out through telephone interviews. Questions included physician-diagnosed osteoporosis, demographic and lifestyle variables, medical conditions, and present and past use of estrogen-containing medications. Body mass index (BMI) was calculated from reported height and weight. A national population-based survey conducted from March through August 1998. A national random sample of 888 women aged 45-74. The overall prevalence of self-reported osteoporosis was estimated at 13.7%. The rates increased abruptly from about 5.8% at ages 45-59 to 19.6% at ages 60-64, and reached 27.7% at ages 70-74. Between ages 45-59, the rates were higher among Arab women, whereas in the older group they were higher among Jewish women. There was a marked increase following menopause. After adjustment for potential confounders, at ages 45-59, osteoporosis was positively associated with menopause and BMI, whereas at ages 60-74, it was positively associated with age and family history of osteoporosis, and negatively associated with BMI. The prevalence of physician-diagnosed osteoporosis in Israel among women aged 45-74 is estimated to be 13.7%, which is similar to that for the United States. The association of osteoporosis with risk factors is age-dependent, and in particular, age-BMI interaction on osteoporosis requires further investigation.

Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study

PubMed Central

2009-01-01

OBJECTIVE—To examine associations of neonatal adiposity with maternal glucose levels and cord serum C-peptide in a multicenter multinational study, the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study, thereby assessing the Pederson hypothesis linking maternal glycemia and fetal hyperinsulinemia to neonatal adiposity. RESEARCH DESIGN AND METHODS—Eligible pregnant women underwent a standard 75-g oral glucose tolerance test between 24 and 32 weeks gestation (as close to 28 weeks as possible). Neonatal anthropometrics and cord serum C-peptide were measured. Associations of maternal glucose and cord serum C-peptide with neonatal adiposity (sum of skin folds >90th percentile or percent body fat >90th percentile) were assessed using multiple logistic regression analyses, with adjustment for potential confounders, including maternal age, parity, BMI, mean arterial pressure, height, gestational age at delivery, and the baby's sex. RESULTS—Among 23,316 HAPO Study participants with glucose levels blinded to caregivers, cord serum C-peptide results were available for 19,885 babies and skin fold measurements for 19,389. For measures of neonatal adiposity, there were strong statistically significant gradients across increasing levels of maternal glucose and cord serum C-peptide, which persisted after adjustment for potential confounders. In fully adjusted continuous variable models, odds ratios ranged from 1.35 to 1.44 for the two measures of adiposity for fasting, 1-h, and 2-h plasma glucose higher by 1 SD. CONCLUSIONS—These findings confirm the link between maternal glucose and neonatal adiposity and suggest that the relationship is mediated by fetal insulin production and that the Pedersen hypothesis describes a basic biological relationship influencing fetal growth. PMID:19011170

The association of remotely-sensed outdoor temperature with blood pressure levels in REGARDS: a cross-sectional study of a large, national cohort of African-American and white participants

PubMed Central

2011-01-01

Background Evidence is mounting regarding the clinically significant effect of temperature on blood pressure. Methods In this cross-sectional study the authors obtained minimum and maximum temperatures and their respective previous week variances at the geographic locations of the self-reported residences of 26,018 participants from a national cohort of blacks and whites, aged 45+. Linear regression of data from 20,623 participants was used in final multivariable models to determine if these temperature measures were associated with levels of systolic or diastolic blood pressure, and whether these relations were modified by stroke-risk region, race, education, income, sex hypertensive medication status, or age. Results After adjustment for confounders, same-day maximum temperatures 20°F lower had significant associations with 1.4 mmHg (95% CI: 1.0, 1.9) higher systolic and 0.5 mmHg (95% CI: 0.3, 0.8) higher diastolic blood pressures. Same-day minimum temperatures 20°F lower had a significant association with 0.7 mmHg (95% CI: 0.3, 1.0) higher systolic blood pressures but no significant association with diastolic blood pressure differences. Maximum and minimum previous-week temperature variabilities showed significant but weak relationships with blood pressures. Parameter estimates showed effect modification of negligible magnitude. Conclusions This study found significant associations between outdoor temperature and blood pressure levels, which remained after adjustment for various confounders including season. This relationship showed negligible effect modification. PMID:21247466

Food Insecurity and Eating Behavior Relationships Among Congregate Meal Participants in Georgia.

PubMed

Myles, TaMara; Porter Starr, Kathryn N; Johnson, Kristen B; Sun Lee, Jung; Fischer, Joan G; Ann Johnson, Mary

2016-01-01

This study explored relationships of food insecurity with cognitive restraint, uncontrolled eating, and emotional eating behaviors among congregate meal participants in northeast Georgia [n = 118 years, age 60 years and older, mean (SD) age = 75 ( 8 ) years, 75% female, 43% Black, 53% obese (Body Mass Index ≥ 30)]. Food insecurity was assessed with a 6-item questionnaire. Scores ranged from 0 to 6 and were defined as high or marginal food security, FS, 0-1 (70%); low food security, LFS, 2-4 (20%); very low food security, VLFS, 5-6 (10%); and low and very low food security, LVLFS, 2-6 (30%). Eating behavior was assessed with an 18-item Three-Factor Eating Questionnaire R-18. In bivariate analyses food insecurity was consistently associated with cognitive restraint scores above the median split and to a lesser extent with uncontrolled eating scores (p ≤ 0.05). No association was found between emotional eating and food insecurity. In multivariate linear and logistic regression analyses, food insecurity was consistently associated with cognitive restraint (p ≤ 0.05) even when controlled for potential confounders (demographics, Body Mass Index, and chronic diseases). Food insecurity was also associated with uncontrolled eating (p ≤ 0.05), but the relationship was attenuated when controlled for potential confounding variables. Although cognitive restraint is defined as the conscious restriction of food intake to control body weight or promote weight loss, these findings suggest there may be other dimensions of cognitive restraint to consider in nutritional assessment and interventions among food-insecure older adults.

Family meals and body mass index among adolescents: effects of gender.

PubMed

Goldfield, Gary S; Murray, Marisa A; Buchholz, Annick; Henderson, Katherine; Obeid, Nicole; Kukaswadia, Atif; Flament, Martine F

2011-08-01

Family meals have been identified as a protective factor against obesity among youth. However, gender specificities with respect to the relationship between the frequency of family meals and body mass index (BMI) have not been investigated. The purpose of this study was to examine the relationship between the frequency of family meals and BMI in male and female adolescents, while controlling for potential confounding factors associated with BMI, such as parental education, adolescent's age, and snack-food eating. Research participants were 734 male and 1030 female students (mean age, 14.12 years, SD = 1.62) recruited from middle schools and high schools in the capital region of Canada. Participants completed validated, self-report measures to assess the frequency of family meals and the risk factors associated with increased BMI, which was derived from objective measures of height and weight. After controlling for proposed confounding variables, a higher frequency of family meals was associated with lower BMI in females, but not in males. A Z-transformation test of the homogeneity of adjusted correlation coefficients showed a significant trend (p = 0.06), indicating that the relationship between family meals and BMI is stronger in females than males, consistent with our regression analyses. Our findings suggest that eating together as a family may be a protective factor against obesity in female adolescents, but not in male adolescents. Findings from this study have important implications for parents and health care practitioners advocating for more frequent family meals as part of a comprehensive obesity prevention and treatment program for female adolescents.

Prenatal depression effects and interventions: a review.

PubMed

Field, Tiffany; Diego, Miguel; Hernandez-Reif, Maria

2010-12-01

This review covers research on the negative effects of prenatal depression and cortisol on fetal growth, prematurity and low birthweight. Although prenatal depression and cortisol were typically measured at around 20 weeks gestation, other research suggests the stability of depression and cortisol levels across pregnancy. Women with Dysthymia as compared to Major Depression Disorder had higher cortisol levels, and their newborns had lower gestational age and birthweight. The cortisol effects in these studies were unfortunately confounded by low serotonin and low dopamine levels which in themselves could contribute to non-optimal pregnancy outcomes. The negative effects of depression and cortisol were also potentially confounded by comorbid anxiety, by demographic factors including younger age, less education and lower SES of the mothers and by the absence of a partner or a partner who was unhappy about the pregnancy or a partner who was depressed. Substance use (especially caffeine use) was still another risk factor. All of these problems including prenatal depression, elevated cortisol, prematurity and low birthweight and even postpartum depression have been reduced by prenatal massage therapy provided by the women's partners. Massage therapy combined with group interpersonal psychotherapy was also effective for reducing depression and cortisol levels. Several limitations of these studies were noted and suggestions for future research included exploring other predictor variables like progesterone/estriol ratios, immune factors and genetic determinants. Further research is needed both on the potential use of cortisol as a screening measure and the use of other therapies that might reduce prenatal depression and cortisol in the women and prematurity and low birthweight in their infants. Copyright © 2010 Elsevier Inc. All rights reserved.

Task-switching cost and repetition priming: two overlooked confounds in the first-set procedure of the Sternberg paradigm and how they affect memory set-size effects.

PubMed

Jou, Jerwen

2014-10-01

Subjects performed Sternberg-type memory recognition tasks (Sternberg paradigm) in four experiments. Category-instance names were used as learning and testing materials. Sternberg's original experiments demonstrated a linear relation between reaction time (RT) and memory-set size (MSS). A few later studies found no relation, and other studies found a nonlinear relation (logarithmic) between the two variables. These deviations were used as evidence undermining Sternberg's serial scan theory. This study identified two confounding variables in the fixed-set procedure of the paradigm (where multiple probes are presented at test for a learned memory set) that could generate a MSS RT function that was either flat or logarithmic rather than linearly increasing. These two confounding variables were task-switching cost and repetition priming. The former factor worked against smaller memory sets and in favour of larger sets whereas the latter factor worked in the opposite way. Results demonstrated that a null or a logarithmic RT-to-MSS relation could be the artefact of the combined effects of these two variables. The Sternberg paradigm has been used widely in memory research, and a thorough understanding of the subtle methodological pitfalls is crucial. It is suggested that a varied-set procedure (where only one probe is presented at test for a learned memory set) is a more contamination-free procedure for measuring the MSS effects, and that if a fixed-set procedure is used, it is worthwhile examining the RT function of the very first trials across the MSSs, which are presumably relatively free of contamination by the subsequent trials.

Improving observational study estimates of treatment effects using joint modeling of selection effects and outcomes: the case of AAA repair.

PubMed

O'Malley, A James; Cotterill, Philip; Schermerhorn, Marc L; Landon, Bruce E

2011-12-01

When 2 treatment approaches are available, there are likely to be unmeasured confounders that influence choice of procedure, which complicates estimation of the causal effect of treatment on outcomes using observational data. To estimate the effect of endovascular (endo) versus open surgical (open) repair, including possible modification by institutional volume, on survival after treatment for abdominal aortic aneurysm, accounting for observed and unobserved confounding variables. Observational study of data from the Medicare program using a joint model of treatment selection and survival given treatment to estimate the effects of type of surgery and institutional volume on survival. We studied 61,414 eligible repairs of intact abdominal aortic aneurysms during 2001 to 2004. The outcome, perioperative death, is defined as in-hospital death or death within 30 days of operation. The key predictors are use of endo, transformed endo and open volume, and endo-volume interactions. There is strong evidence of nonrandom selection of treatment with potential confounding variables including institutional volume and procedure date, variables not typically adjusted for in clinical trials. The best fitting model included heterogeneous transformations of endo volume for endo cases and open volume for open cases as predictors. Consistent with our hypothesis, accounting for unmeasured selection reduced the mortality benefit of endo. The effect of endo versus open surgery varies nonlinearly with endo and open volume. Accounting for institutional experience and unmeasured selection enables better decision-making by physicians making treatment referrals, investigators evaluating treatments, and policy makers.

Harmonization of multi-site diffusion tensor imaging data.

PubMed

Fortin, Jean-Philippe; Parker, Drew; Tunç, Birkan; Watanabe, Takanori; Elliott, Mark A; Ruparel, Kosha; Roalf, David R; Satterthwaite, Theodore D; Gur, Ruben C; Gur, Raquel E; Schultz, Robert T; Verma, Ragini; Shinohara, Russell T

2017-11-01

Diffusion tensor imaging (DTI) is a well-established magnetic resonance imaging (MRI) technique used for studying microstructural changes in the white matter. As with many other imaging modalities, DTI images suffer from technical between-scanner variation that hinders comparisons of images across imaging sites, scanners and over time. Using fractional anisotropy (FA) and mean diffusivity (MD) maps of 205 healthy participants acquired on two different scanners, we show that the DTI measurements are highly site-specific, highlighting the need of correcting for site effects before performing downstream statistical analyses. We first show evidence that combining DTI data from multiple sites, without harmonization, may be counter-productive and negatively impacts the inference. Then, we propose and compare several harmonization approaches for DTI data, and show that ComBat, a popular batch-effect correction tool used in genomics, performs best at modeling and removing the unwanted inter-site variability in FA and MD maps. Using age as a biological phenotype of interest, we show that ComBat both preserves biological variability and removes the unwanted variation introduced by site. Finally, we assess the different harmonization methods in the presence of different levels of confounding between site and age, in addition to test robustness to small sample size studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluating the effectiveness of Washington state repeated job search services on the employment rate of prime-age female welfare recipients☆

PubMed Central

Hsiao, Cheng; Shen, Yan; Wang, Boqing; Weeks, Greg

2014-01-01

This paper uses an unbalanced panel dataset to evaluate how repeated job search services (JSS) and personal characteristics affect the employment rate of the prime-age female welfare recipients in the State of Washington. We propose a transition probability model to take into account issues of sample attrition, sample refreshment and duration dependence. We also generalize Honoré and Kyriazidou’s [Honoré, B.E., Kyriazidou, E., 2000. Panel data discrete choice models with lagged dependent variables. Econometrica 68 (4), 839–874] conditional maximum likelihood estimator to allow for the presence of individual-specific effects. A limited information test is suggested to test for selection issues in non-experimental data. The specification tests indicate that the (conditional on the set of the confounding variables considered) assumptions of no selection due to unobservables and/or no unobserved individual-specific effects are not violated. Our findings indicate that the first job search service does have positive and significant impacts on the employment rate. However, providing repeated JSS to the same client has no significant impact. Further, we find that there are significant experience-enhancing effects. These findings suggest that providing one job search services training to individuals may have a lasting impact on raising their employment rates. PMID:26052178

Cardiovascular risk factors in the normoglycaemic Asian-Indian population--influence of urbanisation.

PubMed

Snehalatha, C; Ramachandran, A

2009-04-01

The aim of this study was to investigate the prevalence of cardiovascular risk factors in normoglycaemic Asian-Indians and its association with urbanisation and plasma glucose. Data on 5,517 normoglycaemic individuals aged >/=20 years (1,521, 1,851 and 2,145 inhabitants of a city, a town and villages, respectively), from a 2006 diabetes survey, were used. The presence of single and multiple abnormalities, including obesity, abdominal obesity, hypertension and dyslipidaemia, was analysed. Risk associations for hypertension and dyslipidaemia were analysed using multivariate analysis after adjusting for confounding variables. Both the prevalence and clustering of cardiovascular risk variables were higher in urban areas than in villages, and were higher in the city than in the town. Nearly half (47%) of the normoglycaemic individuals from villages had at least one risk factor. Age, male sex, BMI, waist circumference, lack of physical activity and living in an urban environment were associated with hypertension and dyslipidaemia; postprandial glucose level showed no association with hypertension or dyslipidaemia after adjusting for these risk factors. Fasting plasma glucose level showed an independent association with dyslipidaemia. There is a high prevalence of cardiovascular risk factors even among normoglycaemic individuals, and this is highest in urban areas. Fasting plasma glucose level showed an association with dyslipidaemia but not hypertension.

Evaluating the effectiveness of Washington state repeated job search services on the employment rate of prime-age female welfare recipients.

PubMed

Hsiao, Cheng; Shen, Yan; Wang, Boqing; Weeks, Greg

2008-07-01

This paper uses an unbalanced panel dataset to evaluate how repeated job search services (JSS) and personal characteristics affect the employment rate of the prime-age female welfare recipients in the State of Washington. We propose a transition probability model to take into account issues of sample attrition, sample refreshment and duration dependence. We also generalize Honoré and Kyriazidou's [Honoré, B.E., Kyriazidou, E., 2000. Panel data discrete choice models with lagged dependent variables. Econometrica 68 (4), 839-874] conditional maximum likelihood estimator to allow for the presence of individual-specific effects. A limited information test is suggested to test for selection issues in non-experimental data. The specification tests indicate that the (conditional on the set of the confounding variables considered) assumptions of no selection due to unobservables and/or no unobserved individual-specific effects are not violated. Our findings indicate that the first job search service does have positive and significant impacts on the employment rate. However, providing repeated JSS to the same client has no significant impact. Further, we find that there are significant experience-enhancing effects. These findings suggest that providing one job search services training to individuals may have a lasting impact on raising their employment rates.

Neonatal pain-related stress, functional cortical activity and visual-perceptual abilities in school-age children born at extremely low gestational age

PubMed Central

Doesburg, Sam M.; Chau, Cecil M.; Cheung, Teresa P.L.; Moiseev, Alexander; Ribary, Urs; Herdman, Anthony T.; Miller, Steven P.; Cepeda, Ivan L.; Synnes, Anne; Grunau, Ruth E.

2013-01-01

Children born very prematurely (≤32 weeks) often exhibit visual-perceptual difficulties at school-age, even in the absence of major neurological impairment. The alterations in functional brain activity that give rise to such problems, as well as the relationship between adverse neonatal experience and neurodevelopment, remain poorly understood. Repeated procedural pain-related stress during neonatal intensive care has been proposed to contribute to altered neurocognitive development in these children. Due to critical periods in the development of thalamocortical systems, the immature brain of infants born at extremely low gestational age (ELGA; ≤28 weeks) may have heightened vulnerability to neonatal pain. In a cohort of school-age children followed since birth we assessed relations between functional brain activity measured using magnetoencephalogragy (MEG), visual-perceptual abilities and cumulative neonatal pain. We demonstrated alterations in the spectral structure of spontaneous cortical oscillatory activity in ELGA children at school-age. Cumulative neonatal pain-related stress was associated with changes in background cortical rhythmicity in these children, and these alterations in spontaneous brain oscillations were negatively correlated with visual-perceptual abilities at school-age, and were not driven by potentially confounding neonatal variables. These findings provide the first evidence linking neonatal painrelated stress, the development of functional brain activity, and school-age cognitive outcome in these vulnerable children. PMID:23711638

Effect of DHEAS on skeletal muscle over the life span: the InCHIANTI study.

PubMed

Valenti, Giorgio; Denti, Licia; Maggio, Marcello; Ceda, GianPaolo; Volpato, Stefano; Bandinelli, Stefania; Ceresini, Graziano; Cappola, Anne; Guralnik, Jack M; Ferrucci, Luigi

2004-05-01

It has been suggested that the reduced production of dehydroepiandrosterone sulfate (DHEAS) may be partially responsible for the decline of muscle strength and mass that often occurs with aging. However, this hypothesis has been only tested in small series of normal volunteers, with little consideration for potential confounders. Using data from a representative sample of 558 men (20-95 years) we tested the hypothesis that circulating DHEAS is independently associated with muscle strength and mass. Data are from InCHIANTI, an epidemiological study conducted in the Chianti geographic area (Tuscany, Italy). DHEAS serum levels were related to lower extremity muscle strength assessed by hand-held dynamometry and calf muscle area estimated from quantitative computerized tomography. Confounders included age, anthropometrics, physical activity, smoking, energy and alcohol intake, albumin, lipids, interleukin-6, comorbidity, depressive symptoms, and disability in activities of daily living. In fully adjusted models predicting lower extremity muscle strength and calf muscle area, we found significant age*log DHEAS interactions, suggesting that the relationship between DHEAS levels and muscle parameters differs across the life span. In age-stratified models adjusted for confounders, serum DHEAS was an independent predictor of muscle strength (p <.02) and mass (p <.01), but only for men between 60 and 79 years of age. After adjusting these models for serum-free or bioavailable testosterone, results were unchanged. In men aged 60-79 years, circulating DHEAS is an independent correlate of muscle strength and calf muscle area. The possible causal role of declining DHEAS in age-related sarcopenia should be further explored in longitudinal studies.

Association between Sleep Disturbances and Leisure Activities in the Elderly: A Comparison between Men and Women

PubMed Central

Hellström, Amanda; Hellström, Patrik; Fagerström, Cecilia

2014-01-01

It has been suggested that physical or social activity is associated with fewer sleep disturbances among elderly people. Women report more sleep disturbances than men, which could indicate a variation in activity patterns between the genders. The aim of this study was to investigate associations between sleep disturbances and leisure activities in men and women (n = 945) aged ≥60 years in a Swedish population. Sleep disturbances were measured using eight dichotomous questions and seventeen variables, covering a wide range of leisure activities. Few leisure activities were found to be associated with sleep disturbances and their importance decreased when the models were adjusted for confounders and gender interactions. After clustering the leisure activities and investigating individual activities, sociointellectual activities were shown to be significant for sleep. However, following adjustment for confounders and gender interactions, home maintenance was the only activity significant for sleep. Being a female increased the effect of home maintenance. Besides those leisure activities, poor/fair self-rated health (OR 7.50, CI: 4.27–11.81) and being female (OR 4.86, CI: 2.75–8.61) were found to have the highest association with poor sleep. Leisure activities pursued by elderly people should focus on activities of a sociointellectual nature, especially among women, to promote sleep. PMID:24575303

Correlates of residential wiring code used in studies of health effects of residential electromagnetic fields.

PubMed

Bracken, M B; Belanger, K; Hellenbrand, K; Addesso, K; Patel, S; Triche, E; Leaderer, B P

1998-09-01

The home wiring code is the most widely used metric for studies of residential electromagnetic field (EMF) exposure and health effects. Despite the fact that wiring code often shows stronger correlations with disease outcome than more direct EMF home assessments, little is known about potential confounders of the wiring code association. In a study carried out in southern Connecticut in 1988-1991, the authors used strict and widely used criteria to assess the wiring codes of 3,259 homes in which respondents lived. They also collected other home characteristics from the tax assessor's office, estimated traffic density around the home from state data, and interviewed each subject (2,967 mothers of reproductive age) for personal characteristics. Women who lived in very high current configuration wiring coded homes were more likely to be in manual jobs and their homes were older (built before 1949, odds ratio (OR) = 73.24, 95% confidence interval (CI) 29.53-181.65) and had lower assessed value and higher traffic densities (highest density quartile, OR = 3.99, 95% CI 1.17-13.62). Because some of these variables have themselves been associated with health outcomes, the possibility of confounding of the wiring code associations must be rigorously evaluated in future EMF research.

Logistic Regression Likelihood Ratio Test Analysis for Detecting Signals of Adverse Events in Post-market Safety Surveillance.

PubMed

Nam, Kijoeng; Henderson, Nicholas C; Rohan, Patricia; Woo, Emily Jane; Russek-Cohen, Estelle

2017-01-01

The Vaccine Adverse Event Reporting System (VAERS) and other product surveillance systems compile reports of product-associated adverse events (AEs), and these reports may include a wide range of information including age, gender, and concomitant vaccines. Controlling for possible confounding variables such as these is an important task when utilizing surveillance systems to monitor post-market product safety. A common method for handling possible confounders is to compare observed product-AE combinations with adjusted baseline frequencies where the adjustments are made by stratifying on observable characteristics. Though approaches such as these have proven to be useful, in this article we propose a more flexible logistic regression approach which allows for covariates of all types rather than relying solely on stratification. Indeed, a main advantage of our approach is that the general regression framework provides flexibility to incorporate additional information such as demographic factors and concomitant vaccines. As part of our covariate-adjusted method, we outline a procedure for signal detection that accounts for multiple comparisons and controls the overall Type 1 error rate. To demonstrate the effectiveness of our approach, we illustrate our method with an example involving febrile convulsion, and we further evaluate its performance in a series of simulation studies.

Racial and ethnic differences in utilization of mental health services among high-risk youths.

PubMed

Garland, Ann F; Lau, Anna S; Yeh, May; McCabe, Kristen M; Hough, Richard L; Landsverk, John A

2005-07-01

Racial and ethnic disparities in mental health service use have been identified as a major public health problem. However, the extent to which these disparities may be accounted for by other confounding sociodemographic or clinical predictors of service use (e.g., family income, functional impairment, caregiver strain) is relatively unexplored, especially for youth services. The goal of this study was to test for racial/ethnic disparities in use of a variety of outpatient, inpatient, and informal mental health services among high-risk youths, with the effects of other predictive factors controlled. Participants were 1,256 youths ages 6-18 years who received services in a large, publicly funded system of care (including the child welfare, juvenile justice, special education, alcohol and drug abuse, and mental health service sectors). Youths and caregivers were interviewed with established measures of mental health service use, psychiatric diagnoses, functional impairment, caregiver strain, and parental depression. Significant racial/ethnic group differences in likelihood of receiving any mental health service and, specifically, formal outpatient services were found after the effects of potentially confounding variables were controlled. Race/ethnicity did not exert a significant effect on the use of informal or 24-hour-care services. Racial/ethnic disparities in service use remain a public health problem.

Prospective Association Between Negative Life Events and Initiation of Sexual Intercourse: The Influence of Family Structure and Family Income

PubMed Central

Oman, Roy F.; Vesely, Sara K.; Aspy, Cheryl B.; Tolma, Eleni L.; John, Robert

2015-01-01

Objectives. We examined the prospective association between negative life events and time to initiation of sexual intercourse and the influence of family structure and family income on this association. Methods. We followed up a randomly selected sample (n = 649) of ethnically diverse parents and their children aged 12 to 17 years over a 5-year period. We conducted Cox proportional hazards regression analysis to examine the relation between negative life events and time to initiation of sexual intercourse. Family structure and family income were assessed as confounders. Results. Negative life events were significant predictors of time to initiation of sexual intercourse in adolescents. After controlling for demographic variables, youths reporting 1 negative life event had a hazard of initiation of sexual intercourse 1.40 times greater and youths reporting 2 or more negative life events had a hazard of initiation of sexual intercourse 1.61 times greater compared with youths reporting no negative life events. Family structure and family income were not significant confounders of the relation between initiation of sexual intercourse and negative life events. Conclusions. Interventions to prevent initiation of sexual intercourse should focus on youths with recent negative life events, regardless of family income and structure. PMID:25602885

Association between Sleep Disturbances and Leisure Activities in the Elderly: A Comparison between Men and Women.

PubMed

Hellström, Amanda; Hellström, Patrik; Willman, Ania; Fagerström, Cecilia

2014-01-01

It has been suggested that physical or social activity is associated with fewer sleep disturbances among elderly people. Women report more sleep disturbances than men, which could indicate a variation in activity patterns between the genders. The aim of this study was to investigate associations between sleep disturbances and leisure activities in men and women (n = 945) aged ≥60 years in a Swedish population. Sleep disturbances were measured using eight dichotomous questions and seventeen variables, covering a wide range of leisure activities. Few leisure activities were found to be associated with sleep disturbances and their importance decreased when the models were adjusted for confounders and gender interactions. After clustering the leisure activities and investigating individual activities, sociointellectual activities were shown to be significant for sleep. However, following adjustment for confounders and gender interactions, home maintenance was the only activity significant for sleep. Being a female increased the effect of home maintenance. Besides those leisure activities, poor/fair self-rated health (OR 7.50, CI: 4.27-11.81) and being female (OR 4.86, CI: 2.75-8.61) were found to have the highest association with poor sleep. Leisure activities pursued by elderly people should focus on activities of a sociointellectual nature, especially among women, to promote sleep.

Vegetarian diets and depressive symptoms among men.

PubMed

Hibbeln, Joseph R; Northstone, Kate; Evans, Jonathan; Golding, Jean

2018-01-01

Vegetarian diets are associate with cardiovascular and other health benefits, but little is known about mental health benefits or risks. To determine whether self-identification of vegetarian dietary habits is associated with significant depressive symptoms in men. Self-report data from 9668 adult male partners of pregnant women in the Avon Longitudinal Study of Parents and Children (ALSPAC) included identification as vegetarian or vegan, dietary frequency data and the Edinburgh Post Natal Depression Scale (EPDS). Continuous and binary outcomes were assessed using multiple linear and logistic regression taking account of potential confounding variables including: age, marital status, employment status, housing tenure, number of children in the household, religion, family history of depression previous childhood psychiatric contact, cigarette and alcohol consumption. Vegetarians [n = 350 (3.6% of sample)], had higher depression scores on average than non-vegetarians (mean difference 0.96 points [95%CI + 0.53, + 1.40]) and a greater risk for EPDS scores above 10 (adjusted OR = 1.67 [95% CI: 1.14,2.44]) than non-vegetarians after adjustment for potential confounding factors. Vegetarian men have more depressive symptoms after adjustment for socio-demographic factors. Nutritional deficiencies (e.g. in cobalamin or iron) are a possible explanation for these findings, however reverse causation cannot be ruled out. Copyright © 2017. Published by Elsevier B.V.

[The effects of hatha yoga exercises on stress and anxiety levels in mastectomized women].

PubMed

Bernardi, Marina Lima Daleprane; Amorim, Maria Helena Costa; Zandonade, Eliana; Santaella, Danilo Forghieri; Barbosa, Juliana de Assis Novais

2013-12-01

This article seeks to evaluate the effects of hatha yoga on stress and anxiety levels in mastectomized women. It also investigates the relationship between these levels with the following variables: age; marital status; religion; instruction; profession; smoke addiction; elitism; staging of the disease; and treatment phase. This involved controlled random clinical trial sampling of 45 mastectomized women treated at the Ilza Bianco outpatient service of Santa Rita de Cássia Hospital in the Brazilian state of Espírito Santo from March to November 2010. The experimental group participated in 6 individually-applied sessions with incentive for ongoing home practice and was re-evaluated after the period, whereas the control group was re-evaluated after a proportional period. For the study of the variables, the interview and recording on a form technique was used, along with the Anxiety Trait and State Test, and the Stress Symptoms and Signs Test. For statistical treatment, the Statistical Pack for Social Sciences was used. The data are statistically significant and have shown that hatha yoga exercises decrease stress and anxiety in the experimental group. No connection between confounding variables and anxiety and stress levels was found.

The High Prevalence of Incarceration History Among Black Men Who Have Sex With Men in the United States: Associations and Implications

PubMed Central

Magnus, Manya; Kuo, Irene; Wang, Lei; Liu, Ting-Yuan; Mayer, Kenneth H.

2014-01-01

Objectives. We examined lifetime incarceration history and its association with key characteristics among 1553 Black men who have sex with men (BMSM) recruited in 6 US cities. Methods. We conducted bivariate analyses of data collected from the HIV Prevention Trials Network 061 study from July 2009 through December 2011 to examine the relationship between incarceration history and demographic and psychosocial variables predating incarceration and multivariate logistic regression analyses to explore the associations between incarceration history and demographic and psychosocial variables found to be significant. We then used multivariate logistic regression models to explore the independent association between incarceration history and 6 outcome variables. Results. After adjusting for confounders, we found that increasing age, transgender identity, heterosexual or straight identity, history of childhood violence, and childhood sexual experience were significantly associated with incarceration history. A history of incarceration was also independently associated with any alcohol and drug use in the past 6 months. Conclusions. The findings highlight an elevated lifetime incarceration history among a geographically diverse sample of BMSM and the need to adequately assess the impact of incarceration among BMSM in the United States. PMID:24432948

Diet and coronary heart disease in England and Wales during and after the second world war.

PubMed

Barker, D J; Osmond, C

1986-03-01

During the second world war there were large changes in consumption of fats, fibre, and sugar in Britain. These changes matched recent recommendations made by the Committee on Medical Aspects of Food Policy (COMA) with the object of reducing the incidence of coronary heart disease (CHD). It is widely believed that CHD mortality fell during the war. This paper re-examines CHD mortality among middle-aged people in England and Wales from 1931 to 1967. After allowance for changes in the rules for coding cause of death, and for the sharp increase in all-causes mortality in 1940, there is little to suggest that time trends in CHD were much influenced by the war. Because of confounding variables, this does not argue against the COMA report. However, it gives no support to the view that compliance with the recommendations on fat, fibre, and sugar will lead, by itself, to an appreciable fall in CHD mortality in middle-aged people.

Health-Related Behavior Mediates the Association Between Personality and Memory Performance in Older Adults.

PubMed

Allen, Mark S; Laborde, Sylvain; Walter, Emma E

2017-03-01

This prospective study explored the potential mediating role of health-related behavior (alcohol involvement, diet, television viewing, and physical activity) in the association between personality and change in memory performance over 2 years. A nationally representative sample of 8,376 U.K. participants aged 55 years and older (4,572 women, 3,804 men) completed self-report measures of personality and health-related behavior in 2010, and completed a memory performance task in 2010 and 2012. After removing variance associated with potential confounding variables, neuroticism and agreeableness had negative associations, and openness and conscientiousness positive associations with change in memory performance. There were no moderation effects by age, sex, education level, or ethnicity. Multiple mediator models demonstrated that physical activity, television viewing, and alcohol intake mediated associations between personality and change in memory performance. These findings provide evidence that the association between personality and memory performance in older adults can be explained, in part, through health-related behavior.

Health profile and disease determinants among asylum seekers: a cross-sectional retrospective study from an Italian reception centre.

PubMed

Russo, Gianluca; Vita, Serena; Miglietta, Alessandro; Terrazzini, Nadia; Sannella, Alessandra; Vullo, Vincenzo

2016-06-01

Data on diseases' determinants and health status of asylum seekers (ASs) are limited. We performed a cross-sectional retrospective study in a large ASs centre in Italy. Data were collected during a 1-year period. Descriptive statistics were calculated. A χ(2) test was used to assess the association between socio-demographics characteristics of ASs and screening test results. A multiple logistic regression analysis was performed to identify diseases' predictors by using ICD-10 diagnoses classification as outcome variable, socio-demographic characteristics as independent variable and visits' number as confounding variable. Overall, data on 792 ASs (mean age 27 years, 80% males, 58% from Africa) were assessed, 43% underwent voluntary infectious diseases screening and 2843 diagnoses were recorded. The most frequent diagnoses were: respiratory diseases, symptoms/signs not elsewhere classified, digestive diseases and infectious diseases. Gender was the most frequent predictor of ICD-10 diagnoses, while African origin, civil status and education were, respectively, predictive of cardiovascular and infectious diseases, genitourinary diseases and pregnancy-related disorders. Higher mean age was associated with syphilis, HIV and HCV infection and African origin with HIV infection. Communicable diseases were not prevalent in the ASs population we analysed. A stronger cultural mediation support is needed to facilitate prevention, access and continuity of care for ASs. © The Author 2015. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Motivation and Social Cognition in Patients with Schizophrenia.

PubMed

Fervaha, Gagan; Siddiqui, Ishraq; Foussias, George; Agid, Ofer; Remington, Gary

2015-07-01

Social cognition, referring to one's ability to perceive and process social cues, is an important domain in schizophrenia. Numerous studies have demonstrated that patients with schizophrenia have poorer performance on tests assessing social cognition relative to healthy comparison participants. However, whether variables such as motivation are related to performance on these tests in patients with schizophrenia is unclear. One thousand three-hundred and seventy-eight patients with schizophrenia completed the Facial Emotion Discrimination Task as a measure of emotional processing, a key facet of social cognition. Level of motivation was also evaluated in these patients using a derived measure from the Quality of Life Scale. The relationship between motivation and task performance was examined using bivariate correlations and logistic regression modeling, controlling for the impact of age and overall severity of psychopathology, the latter evaluated using the Positive and Negative Syndrome Scale. Motivation was positively related to performance on the social cognition test, and this relationship remained significant after controlling for potential confounding variables such as age and illness severity. Social cognition was also related to functioning, and the relationship was mediated by level of motivation. The present study found a significant relationship between motivation and performance on a test of social cognition in a large sample of patients with schizophrenia. These findings suggest that amotivation undermines task performance, or alternatively that poor social cognitive ability impedes motivation. Future studies evaluating social cognition in patients with schizophrenia should concurrently assess for variables such as effort and motivation.

JIM-13-0560 R1: Propensity scores for confounder adjustment when assessing the effects of medical interventions using non-experimental study designs

PubMed Central

Stürmer, Til; Wyss, Richard; Glynn, Robert J.; Brookhart, M. Alan

2014-01-01

Treatment effects, especially when comparing two or more therapeutic alternatives as in comparative effectiveness research, are likely to be heterogeneous across age, gender, co-morbidities, and co-medications. Propensity scores (PSs), an alternative to multivariable outcome models to control for measured confounding, have specific advantages in the presence of heterogeneous treatment effects. Implementing PSs using matching or weighting allows us to estimate different overall treatment effects in differently defined populations. Heterogeneous treatment effects can also be due to unmeasured confounding concentrated in those treated contrary to prediction. Sensitivity analyses based on PSs can help to assess such unmeasured confounding. PSs should be considered a primary or secondary analytic strategy in non-experimental medical research, including pharmacoepidemiology and non-experimental comparative effectiveness research. PMID:24520806

Determinants of blood levels of some thrombogenic biomarkers in healthy Arab adolescent subjects.

PubMed

Akanji, Abayomi O; Al-Isa, Abdulwahab N; Thalib, Lukman

2011-10-01

Acute coronary syndromes present clinically as a consequence of plaque rupture and thrombosis possibly related to altered homeostasis of thrombogenic factors. It is speculated that this vulnerability in adults should be predictable from blood levels of thrombogenic biomarkers in children and adolescents. This study aims to examine the determinants and blood levels of lipoprotein(a) [Lp(a)], fibrinogen (FBG) and plasminogen activator inhibitor-1 (PAI-1) in healthy adolescents stratified according to age group, gender and body mass. A total of 774 (316 males 458 females) healthy adolescent Arab subjects aged 10-19 years and attending secondary schools in Kuwait were interviewed by a validated questionnaire for variables relating to socio-demographic variables, diet and physical activity. They also had anthropometry, BP measurement and determination of fasting blood levels of Lp(a), low density lipoprotein (LDL)-cholesterol, apolipoprotein (apo) B, PAI-1 activity and FBG. The median (interquartile range, IQR) plasma levels of PAI-1 activity, FBG, Lp(a) and apoB were respectively 1.59 (0.58-3.78) U/mL, 296 (190-417) mg/dL, 10.0 (4.8-21.0) mg/dL and 0.72 (0.60-0.85) g/L. Boys had significantly higher PAI-1, FBG and apoB concentrations than the girls, although Lp(a) levels were greater in the latter. The overweight and obese subjects tended to have higher levels of LDL, apoB, FBG and PAI-1 but not Lp(a). Furthermore, the younger adolescent males and females (age <14 years) consistently had higher FBG levels than the older ones (age >14 years). Lp(a) and PAI-1 levels did not appear significantly influenced by this age stratification. Bivariate and multivariate analyses with adjustment for putative body mass index (BMI) confounders indicated that the independent determinants of these biomarkers were (i) Lp(a): apoB, gender; (ii) PAI-1: BMI, apoB, diet; (iii) FBG: BMI, gender, age, family income; and (iv) apoB: BMI, gender and PAI-1. The blood levels of the prothrombotic biomarkers ;ibLp(a), PAI-1, and FBG;ic in healthy Kuwaiti adolescent subjects are variably influenced by age, gender, body mass and socio-demographic factors.

Indoor biofuel air pollution and respiratory health: the role of confounding factors among women in highland Guatemala.

PubMed

Bruce, N; Neufeld, L; Boy, E; West, C

1998-06-01

A number of studies have reported associations between indoor biofuel air pollution in developing countries and chronic obstructive lung disease (COLD) in adults and acute lower respiratory infection (ALRI) in children. Most of these studies have used indirect measures of exposure and generally dealt inadequately with confounding. More reliable, quantified information about this presumed effect is an important pre-requisite for prevention, not least because of the technical, economic and cultural barriers to achieving substantial exposure reductions in the world's poorest households, where ambient pollution levels are typically between ten and a hundred times higher than recommended standards. This study was carried out as part of a programme of research designed to inform the development of intervention studies capable of providing quantified estimates of health benefits. The association between respiratory symptoms and the use of open fires and chimney woodstoves ('planchas'), and the distribution of confounding factors, were examined in a cross-sectional study of 340 women aged 15-45 years, living in a poor rural area in the western highlands of Guatemala. The prevalence of reported cough and phlegm was significantly higher for three of six symptom measures among women using open fires. Although this finding is consistent with a number of other studies, none has systematically examined the extent to which strong associations with confounding variables in these settings limit the ability of observational studies to define the effect of indoor air pollution adequately. Very strong associations (P < 0.0001) were found between the type of fire and a number of household and socioeconomic factors including the arrangement of rooms, floor type, and possession of a radio and television. The spouse's economic activity type was also significantly associated (P < 0.05). Thus, while 82% of open fire users had dirt floors and only 18% cement or tile floors, the situation was reversed for plancha users, only 16% of whom had dirt floors. Confounding presents a substantial problem for observational studies of indoor air pollution and health, although there is a reasonable case for believing that the observed association is causal. Intervention studies are required for stronger evidence of this association, and more importantly, to determine the size of health benefit achievable through feasible exposure reductions.

Testing concordance of instrumental variable effects in generalized linear models with application to Mendelian randomization

PubMed Central

Dai, James Y.; Chan, Kwun Chuen Gary; Hsu, Li

2014-01-01

Instrumental variable regression is one way to overcome unmeasured confounding and estimate causal effect in observational studies. Built on structural mean models, there has been considerale work recently developed for consistent estimation of causal relative risk and causal odds ratio. Such models can sometimes suffer from identification issues for weak instruments. This hampered the applicability of Mendelian randomization analysis in genetic epidemiology. When there are multiple genetic variants available as instrumental variables, and causal effect is defined in a generalized linear model in the presence of unmeasured confounders, we propose to test concordance between instrumental variable effects on the intermediate exposure and instrumental variable effects on the disease outcome, as a means to test the causal effect. We show that a class of generalized least squares estimators provide valid and consistent tests of causality. For causal effect of a continuous exposure on a dichotomous outcome in logistic models, the proposed estimators are shown to be asymptotically conservative. When the disease outcome is rare, such estimators are consistent due to the log-linear approximation of the logistic function. Optimality of such estimators relative to the well-known two-stage least squares estimator and the double-logistic structural mean model is further discussed. PMID:24863158

The association between social participation and cognitive function in community-dwelling older populations: Japan Gerontological Evaluation Study at Taisetsu community Hokkaido.

PubMed

Sakamoto, Ai; Ukawa, Shigekazu; Okada, Emiko; Sasaki, Sachiko; Zhao, Wenjing; Kishi, Tomoko; Kondo, Katsunori; Tamakoshi, Akiko

2017-10-01

To study the association between the number of area-level and individual-level social participation items and cognitive function in the community-dwelling older populations of three towns in Hokkaido, Japan. A survey on the frequency of social participation was mailed to those in the Japan Gerontological Evaluation Study 2013 who were aged ≥65 years, were not certified as needing long-term care, and lived in Higashikawa, Higashikagura, or Biei. A subset of participants aged 70-74 years completed the Japanese version of the Montreal Cognitive Assessment in a home visit survey. Both the area-level and individual-level social participation and demographic information were obtained on the self-administered questionnaire. A multilevel analysis using a generalized linear mixed-effects model was used to examine the association between variables in the area-level and individual-level social participation items and cognitive function. Out of 4042 respondents, data from 2576 were used in the area-level analysis. Of those, 180 were aged 70-74 years and completed the home visit survey for the individual-level analysis. A greater number of higher social participation items at the individual level was associated with higher cognitive function scores after adjusting for area-level social participation variables and confounders (regression coefficient: 0.19; 95% confidence interval: 0.03, 0.35). There were no significant associations between area-level social participation item averages and individual-level cognitive function scores. Older populations participating in many kinds of social activities exhibited preserved cognitive function even after adjusting for area-level social participation variables. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The Influence of Prescription Opioid Use Duration and Dose on Development of Treatment Resistant Depression

PubMed Central

Scherrer, Jeffrey F.; Salas, Joanne; Sullivan, Mark D.; Schneider, F. David; Bucholz, Kathleen K.; Burroughs, Thomas; Copeland, Laurel; Ahmedani, Brian; Lustman, Patrick J.

2016-01-01

Long-term prescription opioid use is associated both with new-onset and recurrence of depression. Whether chronic opioid use interferes with depression management has not been reported, therefore we determined whether patients’ longer duration of opioid use and higher opioid dose are associated with new-onset treatment resistant depression (TRD) after controlling for confounding from pain and other variables. Data was obtained from Veteran Health Administration (VHA) de-identified patient medical records. We used a retrospective cohort design from 2000–2012. Eligible subjects (n=6,169) were 18–80 years of age, free of cancer and HIV, diagnosed with depression and opioid-free for the 24-month interval prior to the observation period. Duration of a new prescription for opioid analgesic was categorized as 1–30 days, 31–90 days and >90 days. Morphine-equivalent dose (MED) during follow-up categorized as ≤50 mg versus >50 mg per day. Pain and other sources of confounding were controlled by propensity scores and inverse probability of treatment weighting. Cox proportional hazard models were computed to estimate the association between duration and dose of opioid and onset of TRD. After removing confounding by weighting data, opioid use for 31–90 days and for >90 days, compared to 1–30 days, was significantly associated with new onset TRD (HR=1.25; 95%CI: 1.09–1.45 and HR=1.52; 95%CI: 1.32–1.74, respectively). MED was not associated with new onset TRD. The risk of developing TRD increased as time spent on opioid analgesics increased. Long-term opioid treatment of chronic pain may interfere with treatment of depression. PMID:27497660

Spatial variation in mortality risk for haematological malignancies near a petrochemical refinery: a population-based case-control study

PubMed Central

Di Salvo, Francesca; Meneghini, Elisabetta; Vieira, Veronica; Baili, Paolo; Mariottini, Mauro; Baldini, Marco; Micheli, Andrea; Sant, Milena

2015-01-01

Introduction The study investigated the geographic variation of mortality risk for hematological malignancies (HMs) in order to identify potential high-risk areas near an Italian petrochemical refinery. Material and methods A population-based case-control study was conducted and residential histories for 171 cases and 338 sex- and age-matched controls were collected. Confounding factors were obtained from interviews with consenting relatives for 109 HM deaths and 267 controls. To produce risk mortality maps, two different approaches were applied. We mapped (1) adptive kernel density relative risk estimation (KDE) for case-control studies which estimates a spatial relative risk function using the ratio between cases and controls’ densities, and (2) estimated odds ratios for case-control study data using generalized additive models (GAMs) to smooth the effect of location, a proxy for exposure, while adjusting for confounding variables. Results No high-risk areas for HM mortality were identified among all subjects (men and women combined), by applying both approaches. Using the adaptive KDE approach, we found a significant increase in death risk only among women in a large area 2–6 km southeast of the refinery and the application of GAMs also identified a similarly-located significant high-risk area among women only (global p-value<0.025). Potential confounding risk factors we considered in the GAM did not alter the results. Conclusion Both approaches identified a high-risk area close to the refinery among women only. Those spatial methods are useful tools for public policy management to determine priority areas for intervention. Our findings suggest several directions for further research in order to identify other potential environmental exposures that may be assessed in forthcoming studies based on detailed exposure modeling. PMID:26073202

U.S. military service and the prevalence of metabolic syndrome: Findings from a cross-sectional analysis of the Cooper Center Longitudinal Study, 1979-2013.

PubMed

Janak, Jud C; Pérez, Adriana; Alamgir, Hasanat; Orman, Jean A; Cooper, Sharon P; Shuval, Kerem; DeFina, Laura; Barlow, Carolyn E; Gabriel, Kelley Pettee

2017-02-01

U.S. military service confers both health benefits and risks potentially associated with a clustering of cardiovascular risk factors called metabolic syndrome. However, the association between prior military service and metabolic syndrome has not sufficiently been examined. The purpose of the study was to compare the prevalence of metabolic syndrome by prior military service status. Among 42,370 men (887 with prior military service) examined from 1979 to 2013 at the Cooper Clinic (Dallas, TX), we used a cross-sectional study design to examine the association between military service and metabolic syndrome. First, an unadjusted log binomial regression model was performed by regressing the prevalence of metabolic syndrome on prior service. This was followed by performing Kleinbaum's modeling strategy for assessing confounding. The same methodology was used to explore the association between individual metabolic syndrome risk factors and prior service. Prior military service was not significantly associated with the prevalence of metabolic syndrome (PR=0.98, 0.89-1.07). None of the variables explored were identified as confounders. Participants with prior military service had lower prevalence of both elevated levels of triglycerides (PR=0.89, 0.80-0.99) and low levels of high-density lipoprotein-cholesterol (PR=0.78, 0.70-0.88). They had a higher prevalence of elevated resting systolic blood pressure (PR=1.23, 1.12-1.35). However, none of these associations were significant after adjusting for identified confounders: age; cardiorespiratory fitness; and exam year. Study findings indicate that military service was not independently associated with the prevalence of metabolic syndrome or its components. Future research is warranted longitudinally assessing the impact of military service on long-term outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

Pretest online discussion groups to augment teaching and learning.

PubMed

Kuhn, Jonathan; Hasbargen, Barbara; Miziniak, Halina

2010-01-01

Tests and final examination scores of three semesters of control students in a nursing foundation course were compared with tests and final examination scores of three semesters of participating students. Participating students were offered access to an asynchronous pretest online discussion activity with a faculty e-moderator. While the simplified Bloom's revised taxonomy assisted in creating appropriate preparatory test and final examination questions for pretest online discussion, Salmon's five-stage online method provided direction to the e-moderator on how to encourage students to achieve Bloom's higher-order thinking skills during the pretest online discussions. Statistical analysis showed the pretest online discussion activity had a generally positive impact on tests and final examination scores, when controlling for a number of possible confounding variables, including instructor, cumulative grade point average, age, and credit hours.

The individualistic fallacy, ecological studies and instrumental variables: a causal interpretation.

PubMed

Loney, Tom; Nagelkerke, Nico J

2014-01-01

The validity of ecological studies in epidemiology for inferring causal relationships has been widely challenged as observed associations could be biased by the Ecological Fallacy. We reconsider the important design components of ecological studies, and discuss the conditions that may lead to spurious associations. Ecological associations are useful and valid when the ecological exposures can be interpreted as Instrumental Variables. A suitable example may be a time series analysis of environmental pollution (e.g. particulate matter with an aerodynamic diameter of <10 micrometres; PM10) and health outcomes (e.g. hospital admissions for acute myocardial infarction) as environmental pollution levels are a cause of individual exposure levels and not just an aggregate measurement. Ecological exposures may also be employed in situations (perhaps rare) where individual exposures are known but their associations with health outcomes are confounded by unknown or unquantifiable factors. Ecological associations have a notorious reputation in epidemiology and individualistic associations are considered superior to ecological associations because of the "ecological fallacy". We have argued that this is incorrect in situations in which ecological or aggregate exposures can serve as an instrumental variable and associations between individual exposure and outcome are likely to be confounded by unmeasured variables.

Infant feeding and mental and motor development at 18 months of age in first born singletons.

PubMed

Florey, C D; Leech, A M; Blackhall, A

1995-01-01

To determine the relationship between type of infant feeding and mental and psychomotor development at age 18 months. A follow-up study of children born to primigravidae living in Dundee and booked into antenatal clinics in the City of Dundee (Local Authority District) from 1 May 1985 to 30 April 1986. The study population was 846 first born singletons, of whom 592 attended for developmental assessment at age 18 months. The main outcome measures were the Bayley Scales of Infant Mental and Motor Development. Higher mental development was significantly related to breast feeding on discharge from hospital and according to the health visitors' notes at about 2 weeks after discharge after allowing for partner's social class, mother's education, height, alcohol and cigarette consumption; placental weight and the child's sex, birth weight and gestational age at birth. After adjustment for statistically significant variables, the difference in Bayley mental development index between breast and bottle fed infants was between 3.7 and 5.7 units depending on the source of feeding data. No differences were found for psychomotor development or behaviour. The study provides further evidence of a robust statistical association between type of feeding and child intelligence. However, the literature is replete with suggestions for potential confounding variables which offer alternative causal explanations. To unravel what is an important clinical and public health question, further research should concentrate on randomized trials of supplemented formula feeds for children of mothers opting for bottle feeding and on epidemiological studies designed to disentangle the relation between method of feeding, parental intelligence and social environment.

Dissatisfaction with cutaneous body image is directly correlated with insomnia severity: A prospective study in a non-clinical sample.

PubMed

Gupta, Madhulika A; Gupta, Aditya K; Knapp, Katie

2015-04-01

Sleep deprivation can physically affect skin appearance, e.g. increase the cutaneous signs of aging. There are no studies of sleep disorders and subjective ratings of skin appearance or cutaneous body image (CBI). CBI is an important consideration in the treatment of cosmetically disfiguring dermatologic disorders. We examined the association of insomnia and CBI. As part of a larger study, community-based non-clinical participants completed ratings of insomnia and CBI (also measured 4-weeks post-baseline) using the Cutaneous Body Image Scale (CBIS). 301/311 adults (238 women; mean ± SD age 38.6 ± 14.7 years; 54.5% married; 94.2% "white") completed insomnia and CBI ratings at baseline; 243/301 completed CBI ratings 4-weeks post-baseline. A low CBIS score denotes greater dissatisfaction with CBI. Multiple regression analysis using CBI at baseline as dependent variable and insomnia, age and sex as independent variables revealed that insomnia (β = -0.24, p < 0.001) and female gender (β = -0.25, p < 0.001) but not age (β = -0.097, p = 0.07) were predictors of CBI dissatisfaction (adjusted R(2 )= 0.15, p < 0.001). A similar relationship was observed for CBI ratings 4-weeks post-baseline. CBI dissatisfaction was positively related to insomnia severity, especially among women. Underlying insomnia may confound an individual's self-assessment of their CBI, a finding that has important treatment implications in dermatology.

Tracking Central Hypovolemia with ECG in Humans: Cautions for the Use of Heart Period Variability in Patient Monitoring

DTIC Science & Technology

2010-06-01

without influences that may confound the re- sults (e.g., pain, anxiety , transport conditions, caregiver in- terventions). Second, rather than being...32. Ryan KL, Rickards CA, Muniz GW, Moralez G, Convertino VA: Interindi- vidual variability in heart rate variability ( HRV ) and complexity measure...Raimondi G, Legramante JM, Macerata A: Revisiting the potential of time-domain indexes in short-term HRV analysis. Biomed Tech (Berl) 51:190Y193, 2006

Uncovering cyanobacteria ecological networks from long-term monitoring data using Granger causality analysis

NASA Astrophysics Data System (ADS)

Nelson, N.; Munoz-Carpena, R.; Kaplan, D. A.; Phlips, E. J.

2016-12-01

In many aquatic systems, cyanobacteria form harmful blooms capable of producing toxins, prompting hypoxia, and/or introducing internal nitrogen loads via N2-fixation, among other impacts. Traditionally, system-specific cyanobacteria drivers are determined by performing controlled experiments and bioassays, but these approaches may neglect the influences of confounding factors and over assign importance to only those variables considered within experimental designs. For example, a bioassay may conclude that the cyanobacteria in a particular system are limited by phosphorus, but will not explicitly take into account the role of flow as a control on phosphorus delivery. This study aims to address this analytical gap by identifying environmental controls on cyanobacteria while removing the effects of potentially confounding variables. In the present work, we evaluate a unique long-term (17 year) dataset composed of monthly observations of phytoplankton and zooplankton species abundances, water quality constituents, and hydrologic variables from Lake George, a flow-through lake of the St. Johns River (FL) impacted by cyanobacterial blooms. Using conditional Granger causality analysis, a time series approach that infers causality while removing the effects of confounding variables, data were evaluated to identify biological and physicochemical drivers of cyanobacteria. The analysis was performed for three response variable sets: total cyanobacteria, N2-fixers and non-fixers, and cyanobacteria genera. Results depicted increasing levels of ecological complexity as subdivisions of cyanobacteria became more detailed; whereas causal networks produced from analyses of cyanobacteria genera provided novel insights relevant for management (i.e. nutrients, flow), the total cyanobacteria network only included water temperature as a significant driver. Additionally, the more detailed cyanobacteria subdivisions uncovered that N2-fixation was only evident with the earliest season bloomer, thus indicating that early season bloomers may be facilitating later-season growth. These findings highlight the importance of detailed monitoring efforts, and indicate that greater emphasis needs to be placed on the role of early bloomers in phytoplankton dynamics, as it relates to management efforts.

The role of prenatal care and social risk factors in the relationship between immigrant status and neonatal morbidity: a retrospective cohort study.

PubMed

Paz-Zulueta, María; Llorca, Javier; Sarabia-Lavín, Raquel; Bolumar, Francisco; Rioja, Luis; Delgado, Abraham; Santibáñez, Miguel

2015-01-01

Literature evaluating association between neonatal morbidity and immigrant status presents contradictory results. Poorer compliance with prenatal care and greater social risk factors among immigrants could play roles as major confounding variables, thus explaining contradictions. We examined whether prenatal care and social risk factors are confounding variables in the relationship between immigrant status and neonatal morbidity. Retrospective cohort study: 231 pregnant African immigrant women were recruited from 2007-2010 in northern Spain. A Spanish population sample was obtained by simple random sampling at 1:3 ratio. Immigrant status (Spanish, Sub-Saharan and Northern African), prenatal care (Kessner Index adequate, intermediate or inadequate), and social risk factors were treated as independent variables. Low birth weight (LBW < 2500 grams) and preterm birth (< 37 weeks) were collected as neonatal morbidity variables. Crude and adjusted odds ratios (OR) were estimated by unconditional logistic regression with 95% confidence intervals (95% CI). Positive associations between immigrant women and higher risk of neonatal morbidity were obtained. Crude OR for preterm births in Northern Africans with respect to nonimmigrants was 2.28 (95% CI: 1.04-5.00), and crude OR for LBW was 1.77 (95% CI: 0.74-4.22). However, after adjusting for prenatal care and social risk factors, associations became protective: adjusted OR for preterm birth = 0.42 (95% CI: 0.14-1.32); LBW = 0.48 (95% CI: 0.15-1.52). Poor compliance with prenatal care was the main independent risk factor associated with both preterm birth (adjusted OR inadequate care = 17.05; 95% CI: 3.92-74.24) and LBW (adjusted OR inadequate care = 6.25; 95% CI: 1.28-30.46). Social risk was an important independent risk factor associated with LBW (adjusted OR = 5.42; 95% CI: 1.58-18.62). Prenatal care and social risk factors were major confounding variables in the relationship between immigrant status and neonatal morbidity.

Disparities in cervical screening participation: a comparison of Russian, Somali and Kurdish immigrants with the general Finnish population.

PubMed

Idehen, Esther E; Koponen, Päivikki; Härkänen, Tommi; Kangasniemi, Mari; Pietilä, Anna-Maija; Korhonen, Tellervo

2018-05-04

Cervical cancer is currently ranked as the fourth commonly diagnosed cancer in women globally. A higher incidence has been reported in low- and-middle-income countries, and the disease poses significant public health challenges. Evidence suggests that this disease is preventable by means of regular screening using the Papanicolaou (Pap) test. However, limited knowledge exists about disparities in cervical screening participation among immigrants compared with non-immigrants, in countries with universal cervical screening programmes. We aimed to examine disparities in cervical screening participation among women of Russian, Somali, and Kurdish, origin in Finland, comparing them with the general Finnish population (Finns). We controlled for differences in several socio-demographic and health-related variables as potential confounders. We employed data from the Finnish Migrant Health and Well-being Study 2010-2012 and the National Health 2011 Survey. Data collection involved face-to-face interviews. Data on screening participation in the previous five years from women aged 29-60 were available from 537 immigrants (257 Russians, 113 Somalis, 167 Kurds) and from 436 Finns. For statistical analyses, we used multiple logistic regression. Age-adjusted screening participation rates were as follows: Russians 79% (95% CI 72.9-84.4), Somalis 41% (95% CI 31.4-50.1), and Kurds 64% (95% CI 57.2-70.8), compared with 94% (95% CI 91.4-95.9) among Finns. After additionally adjusting for socio-demographic and health-related confounders, all the immigrant groups showed a significantly lower likelihood of screening participation when compared with Finns. The Odds Ratios were as follows: Russians 0.32 (95% CI 0.18-0.58), Somalis 0.10 (95% CI 0.04-0.23), and Kurds 0.17 (95% CI 0.09-0.35). However, when additionally accounting for country of origin-confounder interactions, such differences were attenuated. Our results indicate disparities in screening participation among these immigrants and a lower likelihood of screening participation compared with the general Finnish population. To improve equity in cervical cancer screening participation, appropriate culturally tailored intervention programmes for each immigrant group might be beneficial.

Identification of factors involved in medication compliance: incorrect inhaler technique of asthma treatment leads to poor compliance

PubMed Central

Darbà, Josep; Ramírez, Gabriela; Sicras, Antoni; García-Bujalance, Laura; Torvinen, Saku; Sánchez-de la Rosa, Rainel

2016-01-01

Objective To identify the impact of delivery device of inhaled corticosteroids and long-acting β2-agonist (ICS/LABA) on asthma medication compliance, and investigate other factors associated with compliance. Materials and methods We conducted a retrospective and multicenter study based on a review of medical registries of asthmatic patients treated with ICS/LABA combinations (n=2,213) whose medical devices were either dry powder inhalers (DPIs, such as Accuhaler®, Turbuhaler®, and NEXThaler®) or pressurized metered-dose inhalers (pMDI). Medication compliance included persistence outcomes through 18 months and medication possession ratios. Data on potential confounders of treatment compliance such as asthma exacerbations, comorbidities, demographic characteristics, and health care resource utilization were also explored. Results The probability of asthma medication compliance in case of DPIs was lower compared to pMDIs, which suggests that inhaler devices influence inhalation therapies. There were additional confounding factors that were considered as explanatory variables of compliance. A worse measure of airflow obstruction (forced expiration volume in 1 second), comorbidities and general practitioner (GP) consultations more than once per month decreased the probability of compliance. Within comorbidities, alcoholism was positively associated with compliance. Patients of 29–39, 40–50, and 51–61 age groups or suffering from more than two exacerbations during the study period were more likely to comply with their medication regime. The effects of DPIs toward compliance varied with the different DPIs. For instance, Accuhaler® had a greater negative effect on compliance compared to Turbuhaler® and Nexthaler® in cases of patients who suffered exacerbations. We found that GP consultations reduced the probability of medication compliance for patients treated with formoterol/budesonide combination. For retired patients, visiting the GP increased the probability of medication compliance. Conclusion We concluded that inhaler devices influence patients’ compliance for long-term asthma medication. The impact of Accuhaler®, Turbuhaler®, and NEXThaler® on medication compliance was negative. We also identified some confounders of medication compliance such as patient’s age, severity of asthma, comorbidities, and health care costs. PMID:26929605

Aging Shapes the Population-Mean and -Dispersion of Gene Expression in Human Brains

PubMed Central

Brinkmeyer-Langford, Candice L.; Guan, Jinting; Ji, Guoli; Cai, James J.

2016-01-01

Human aging is associated with cognitive decline and an increased risk of neurodegenerative disease. Our objective for this study was to evaluate potential relationships between age and variation in gene expression across different regions of the brain. We analyzed the Genotype-Tissue Expression (GTEx) data from 54 to 101 tissue samples across 13 brain regions in post-mortem donors of European descent aged between 20 and 70 years at death. After accounting for the effects of covariates and hidden confounding factors, we identified 1446 protein-coding genes whose expression in one or more brain regions is correlated with chronological age at a false discovery rate of 5%. These genes are involved in various biological processes including apoptosis, mRNA splicing, amino acid biosynthesis, and neurotransmitter transport. The distribution of these genes among brain regions is uneven, suggesting variable regional responses to aging. We also found that the aging response of many genes, e.g., TP37 and C1QA, depends on individuals' genotypic backgrounds. Finally, using dispersion-specific analysis, we identified genes such as IL7R, MS4A4E, and TERF1/TERF2 whose expressions are differentially dispersed by aging, i.e., variances differ between age groups. Our results demonstrate that age-related gene expression is brain region-specific, genotype-dependent, and associated with both mean and dispersion changes. Our findings provide a foundation for more sophisticated gene expression modeling in the studies of age-related neurodegenerative diseases. PMID:27536236

Association between sleep and residential environments in the summertime in Japan.

PubMed

Kayaba, Momoko; Ihara, Tomohiko; Kusaka, Hiroyuki; Iizuka, Satoru; Miyamoto, Kenji; Honda, Yasushi

2014-05-01

We aimed to identify the effect of environmental factors on sleep in the summertime in Japan. A self-reported questionnaire survey was conducted in Japan. Age of participants ranged from 20 to 70 years. The mean Pittsburgh Sleep Quality Index (PSQI) score was 4.9 (±2.7), and 123 (35.0%) participants had scores of >5. According to the results of multivariate logistic regression analysis, the adjusted odds ratio (aOR) for PSQI scores of >5 without installation of air conditioner was 1.8 (95% confidence interval [CI], 1.0-3.3; P<.05), use of a light bulb was 3.7 (95% CI, 1.1-12.6; P<.05), and noise was 2.1 (95% CI, 1.1-4.1; P<.05) after controlling for several confounding variables. Difficulty initiating sleep (DIS) was associated with installation of an air conditioner (1 [reference] to 3 [aOR, 2.5 {95% CI, 1.2-5.1}] and 4 [aOR, 2.8 {95% CI, 1.1-7.1}]) and noise (1 [reference] to 3 [aOR, 2.4 {95% CI, 1.0-5.9}] and 4 [aOR, 8.8 {95% CI, 3.1-25.0}]). Difficulty maintaining sleep (DMS) was associated with installation of a fan (1 [reference] to 2 [aOR, 0.4 {95% CI, 0.2-0.8}] and noise (1 [reference] to 3 [aOR, 2.3 {95% CI, 1.0-5.3}]) after controlling for several confounding variables. Our finding using analysis of the association between residential environments and subjective sleep statuses, which determined that the installation of an air conditioner and lighting equipment might affect sleep, may be useful to discuss sleep environments and improve sleep quality. Copyright © 2014 Elsevier B.V. All rights reserved.

Religion, a social determinant of mortality? A 10-year follow-up of the Health and Retirement Study

PubMed Central

Blevins, John; Kiser, Mimi

2017-01-01

The social determinants of health framework has brought a recognition of the primary importance of social forces in determining population health. Research using this framework to understand the health and mortality impact of social, economic, and political conditions, however, has rarely included religious institutions and ties. We investigate a well-measured set of social and economic determinants along with several measures of religious participation as predictors of adult mortality. Respondents (N = 18,370) aged 50 and older to the Health and Retirement Study were interviewed in 2004 and followed for all-cause mortality to 2014. Exposure variables were religious attendance, importance, and affiliation. Other social determinants of health included gender, race/ethnicity, education, household income, and net worth measured at baseline. Confounders included physical and mental health. Health behaviors and social ties were included as potential explanatory variables. Cox proportional hazards regressions were adjusted for complex sample design. After adjustment for confounders, attendance at religious services had a dose-response relationship with mortality, such that respondents who attended frequently had a 40% lower hazard of mortality (HR = 0.60, 95% CI 0.53–0.68) compared with those who never attended. Those for whom religion was “very important” had a 4% higher hazard (HR = 1.04, 95% CI 1.01–1.07); religious affiliation was not associated with risk of mortality. Higher income and net worth were associated with a reduced hazard of mortality as were female gender, Latino ethnicity, and native birth. Religious participation is multi-faceted and shows both lower and higher hazards of mortality in an adult US sample in the context of a comprehensive set of other social and economic determinants of health. PMID:29261682

Religion, a social determinant of mortality? A 10-year follow-up of the Health and Retirement Study.

PubMed

Idler, Ellen; Blevins, John; Kiser, Mimi; Hogue, Carol

2017-01-01

The social determinants of health framework has brought a recognition of the primary importance of social forces in determining population health. Research using this framework to understand the health and mortality impact of social, economic, and political conditions, however, has rarely included religious institutions and ties. We investigate a well-measured set of social and economic determinants along with several measures of religious participation as predictors of adult mortality. Respondents (N = 18,370) aged 50 and older to the Health and Retirement Study were interviewed in 2004 and followed for all-cause mortality to 2014. Exposure variables were religious attendance, importance, and affiliation. Other social determinants of health included gender, race/ethnicity, education, household income, and net worth measured at baseline. Confounders included physical and mental health. Health behaviors and social ties were included as potential explanatory variables. Cox proportional hazards regressions were adjusted for complex sample design. After adjustment for confounders, attendance at religious services had a dose-response relationship with mortality, such that respondents who attended frequently had a 40% lower hazard of mortality (HR = 0.60, 95% CI 0.53-0.68) compared with those who never attended. Those for whom religion was "very important" had a 4% higher hazard (HR = 1.04, 95% CI 1.01-1.07); religious affiliation was not associated with risk of mortality. Higher income and net worth were associated with a reduced hazard of mortality as were female gender, Latino ethnicity, and native birth. Religious participation is multi-faceted and shows both lower and higher hazards of mortality in an adult US sample in the context of a comprehensive set of other social and economic determinants of health.

Outcomes of deliveries by family physicians or obstetricians: a population-based cohort study using an instrumental variable

PubMed Central

Aubrey-Bassler, Kris; Cullen, Richard M.; Simms, Alvin; Asghari, Shabnam; Crane, Joan; Wang, Peizhong Peter; Godwin, Marshall

2015-01-01

Background: Previous research has suggested that obstetric outcomes are similar for deliveries by family physicians and obstetricians, but many of these studies were small, and none of them adjusted for unmeasured selection bias. We compared obstetric outcomes between these provider types using an econometric method designed to adjust for unobserved confounding. Methods: We performed a retrospective population-based cohort study of all Canadian (except Quebec) hospital births with delivery by family physicians and obstetricians at more than 20 weeks gestational age, with birth weight greater than 500 g, between Apr. 1, 2006, and Mar. 31, 2009. The primary outcomes were the relative risks of in-hospital perinatal death and a composite of maternal mortality and major morbidity assessed with multivariable logistic regression and instrumental variable–adjusted multivariable regression. Results: After exclusions, there were 3600 perinatal deaths and 14 394 cases of maternal morbidity among 799 823 infants and 793 053 mothers at 390 hospitals. For deliveries by family physicians v. obstetricians, the relative risk of perinatal mortality was 0.98 (95% confidence interval [CI] 0.85–1.14) and of maternal morbidity was 0.81 (95% CI 0.70–0.94) according to logistic regression. The respective relative risks were 0.97 (95% CI 0.58–1.64) and 1.13 (95% CI 0.65–1.95) according to instrumental variable methods. Interpretation: After adjusting for both observed and unobserved confounders, we found a similar risk of perinatal mortality and adverse maternal outcome for obstetric deliveries by family physicians and obstetricians. Whether there are differences between these groups for other outcomes remains to be seen. PMID:26303244

Non-auditory effects of noise in industry. VI. A final field study in industry.

PubMed

van Dijk, F J; Souman, A M; de Vries, F F

1987-01-01

Non-auditory effects of noise were studied among 539 male workers from seven industries. The LAeq, assessed by personal noise dosimetry, has been used to study acute effects. Various indices of total noise exposure, involving level and duration, were developed for long-term effect studies. In the analysis close attention was paid to prevent confounding, e.g. by other adverse working conditions. As expected, hearing loss increased with total noise exposure. Tinnitus was related particularly to hearing loss. Dizziness and hoarseness, however, were not related with noise exposure in this study. Also no correlation could be demonstrated between blood pressure and total noise exposure after correction for age, relative weight and various confounding variables. Use of hearing protection, selection processes and incomplete analysis of interactions between independent variables are suggested for possible explanation. About two-thirds of the workers reported noise annoyance. Various aspects were mentioned, such as irritation, surprise and impairment of communication and perception. Mentally stressful tasks appeared to be the most noise-sensitive. Particularly annoying noise sources, mental work load and time pressure had a relatively large impact on noise annoyance in comparison with the influence of noise level (LAeq) itself. Stress responses were not simply related to the noise exposure level, although consistent positive relations could be demonstrated between symptoms of stress and noise annoyance. Various findings led to the conclusion that noise exposure together with stressful mental activities may lead to disturbed concentration, irritation and annoyance. Experienced stress in turn may render workers more susceptible to noise. To overcome some limitations of this study, cohort studies and studies designed to assess interaction-effects are recommended.

Relationship of life-course drinking patterns to diabetes, heart problems, and hypertension among those 40 and older in the 2005 U.S. National Alcohol Survey.

PubMed

Kerr, William C; Ye, Yu

2010-07-01

The goal of this study was to estimate relationships between life-course drinking patterns and the risks of self-reported diabetes, heart problems, and hypertension. Respondents to the 2005 National Alcohol Survey, age 40 and older, reported ever having a doctor or health professional diagnose each of the health-problem outcomes. Retrospective earlier-life drinking patterns were characterized by lifetime abstention and the frequency of 5+ drinking days (i.e., days on which five or more drinks were consumed) in the respondent's teens, 20s, and 30s. Past-year drinking patterns were measured through intake volume and 5+ days. Potential confounders in the domains of demographics, socioeconomic resources, and other health-risk variables-that is, depression, distress, sense of coherence, body mass index, tobacco use, marijuana use, childhood abuse, and family history of alcohol problems--were controlled through propensity-score matching. After matching, lifetime abstainers were found to be at increased risk of diabetes compared with both lifetime and current moderate drinkers. Exdrinkers were found to be at increased risk of diabetes, heart problems, and hypertension. Higher volume drinkers without monthly 5+ days were found to be at reduced risk of diabetes relative to moderate-volume current drinkers. Heavy-occasion drinkers were found to be at increased risk of hypertension. Regular lower quantity alcohol intake may be protective against adult onset of diabetes, but no evidence of protection from heart problems or hypertension was found. Both life course-defined and past year-defined drinking groups exhibit substantial clustering of confounding risk variables, indicating the need for modeling strategies like propensity-score matching. Increased risks among exdrinkers suggest a substantial "sick-quitter" effect.

Empowerment of women and its association with the health of the community.

PubMed

Varkey, Prathibha; Mbbs; Kureshi, Sarah; Lesnick, Timothy

2010-01-01

Empowerment and opportunities to experience power and control in one's life contribute to health and wellness. Although studies have assessed specific factors related to women's empowerment and their influence on health outcomes, there is a dearth of published literature assessing the relationship of the empowerment of women with the overall health of a community. By means of this article, we aim to assess the relationship of women's empowerment with health in 75 countries. We used the gender empowerment measure (GEM), a composite index measuring gender inequality in economic participation and decision making, political participation and decision making, and power over economic resources. All 75 countries with GEM values in the 2006 Human Development Report (HDR) were included in the study. Association between the GEM values and seven health indicators was evaluated using descriptive statistics, scatter plots, and simple and multiple linear regression models. We also controlled for gross domestic product (GDP) as a possible confounding factor and included this variable in the multiple regression models. When GDP was not considered, GEM had a statistically significant association with all health indicator variables except for proportion of 1-year-olds immunized against measles (correlation coefficient 0.063, p = 0.597). After adjusting for GDP, GEM was significantly associated with low birth weight, fertility rate, infant mortality, and age

Effects of gender and executive function on visuospatial working memory in adult obsessive-compulsive disorder.

PubMed

Martoni, Riccardo Maria; Salgari, Giulia; Galimberti, Elisa; Cavallini, Maria Cristina; O'Neill, Joseph

2015-12-01

Visuospatial working memory (VSWM) is the ability of the brain to transiently store and manipulate visual information. VSWM deficiencies have been reported in obsessive-compulsive disorder (OCD), but not consistently, perhaps due to variability in task design and clinical patient factors. To explore this variability, this study assessed effects of the design factors task difficulty and executive organizational strategy and of the clinical factors gender, OCD symptom dimension, and duration of illness on VSWM in OCD. The CANTAB spatial working memory, spatial recognition memory, delayed matching to sample, and stop signal tasks were administered to 42 adult OCD patients and 42 age- and sex-matched healthy controls. Aims were to detect a possible VSWM deficit in the OCD sample, to evaluate influences of the above task and patient factors, to determine the specificity of the deficit to the visuospatial subdomain, and to examine effects of sustained attention as potential neurocognitive confound. We confirmed previous findings of a VSWM deficit in OCD that was more severe for greater memory load (task difficulty) and that was affected by task strategy (executive function). We failed to demonstrate significant deficits in neighboring or confounding neurocognitive subdomains (visual object recognition or visual object short-term memory, sustained attention). Notably, the VSWM deficit was only significant for female patients, adding to evidence for sexual dimorphism in OCD. Again as in prior work, more severe OCD symptoms in the symmetry dimension (but no other dimension) significantly negatively impacted VSWM. Duration of illness had no significant effect on VSWM. VSWM deficits in OCD appear more severe with higher task load and may be mediated through poor task strategy. Such deficits may present mainly in female patients and in (male and female) patients with symmetry symptoms.

Pot binding as a variable confounding plant phenotype: theoretical derivation and experimental observations.

PubMed

Sinclair, Thomas R; Manandhar, Anju; Shekoofa, Avat; Rosas-Anderson, Pablo; Bagherzadi, Laleh; Schoppach, Remy; Sadok, Walid; Rufty, Thomas W

2017-04-01

Theoretical derivation predicted growth retardation due to pot water limitations, i.e., pot binding. Experimental observations were consistent with these limitations. Combined, these results indicate a need for caution in high-throughput screening and phenotyping. Pot experiments are a mainstay in many plant studies, including the current emphasis on developing high-throughput, phenotyping systems. Pot studies can be vulnerable to decreased physiological activity of the plants particularly when pot volume is small, i.e., "pot binding". It is necessary to understand the conditions under which pot binding may exist to avoid the confounding influence of pot binding in interpreting experimental results. In this paper, a derivation is offered that gives well-defined conditions for the occurrence of pot binding based on restricted water availability. These results showed that not only are pot volume and plant size important variables, but the potting media is critical. Artificial potting mixtures used in many studies, including many high-throughput phenotyping systems, are particularly susceptible to the confounding influences of pot binding. Experimental studies for several crop species are presented that clearly show the existence of thresholds of plant leaf area at which various pot sizes and potting media result in the induction of pot binding even though there may be no immediate, visual plant symptoms. The derivation and experimental results showed that pot binding can readily occur in plant experiments if care is not given to have sufficiently large pots, suitable potting media, and maintenance of pot water status. Clear guidelines are provided for avoiding the confounding effects of water-limited pot binding in studying plant phenotype.

Simpson's paradox: A statistician's case study.

PubMed

Chu, Kevin H; Brown, Nathan J; Pelecanos, Anita; Brown, Anthony Ft

2018-02-26

Gender equality and workforce diversity has recently been in the forefront of College discussions. Reasons for the difference between various groups may not be as they initially appeared. The results of comparing the outcome between two groups can sometimes be confounded and even reversed by an unrecognised third variable. This concept is known as Simpson's Paradox, and is illustrated here using a renowned case study on potential gender bias for acceptance to Graduate School at the University of California, Berkeley.  The investigation showed that males were 1.8 times more likely to be admitted to Graduate School than females in 1973. Initially it appeared that women were discriminated against in the selection process. However, when admissions were re-examined at individual Departments of the School, admission tended to be better for women than men in four of six Departments. This contradiction or paradox tells us that the association between admission and gender was dependent upon on Department.  The confounding effect of Department was defined by two characteristics. Firstly, a strong association between Department and admission: some Departments admitted much smaller percentages of applicants than others. Secondly, a strong association between Department and gender: females tended to apply to Departments with lower admission rates.  The explanation of differences between groups can be multifactorial. A search for possible confounders will assist in this understanding. This could apply whenever two groups initially appear to differ, but on closer analysis this difference is either unfounded, or even reversed by reference to a third, confounding variable. © 2018 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Drug induced liver injury with analysis of alternative causes as confounding variables.

PubMed

Teschke, Rolf; Danan, Gaby

2018-04-01

Drug-induced liver injury (DILI) is rare compared to the worldwide frequent acute or chronic liver diseases. Therefore, patients included in series of suspected DILI are at high risk of not having DILI, whereby alternative causes may confound the DILI diagnosis. The aim of this review is to evaluate published case series of DILI for alternative causes. Relevant studies were identified using a computerized search of the Medline database for publications from 1993 through 30 October 2017. We used the following terms: drug hepatotoxicity, drug induced liver injury, hepatotoxic drugs combined with diagnosis, causality assessment and alternative causes. Alternative causes as variables confounding the DILI diagnosis emerged in 22 published DILI case series, ranging from 4 to 47%. Among 13 335 cases of suspected DILI, alternative causes were found to be more likely in 4555 patients (34.2%), suggesting that the suspected DILI was probably not DILI. Biliary diseases such as biliary obstruction, cholangitis, choledocholithiasis, primary biliary cholangitis and primary sclerosing cholangitis were among the most missed diagnoses. Alternative causes included hepatitis B, C and E, cytomegalovirus, Epstein-Barr virus, ischemic hepatitis, cardiac hepatopathy, autoimmune hepatitis, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, and alcoholic liver disease. In more than one-third of published global DILI case series, alternative causes as published in these reports confounded the DILI diagnosis. In the future, published DILI case series should include only patients with secured DILI diagnosis, preferentially established by prospective use of scored items provided by robust diagnostic algorithms such as the updated Roussel Uclaf causality assessment method. © 2018 The British Pharmacological Society.

The effect of ageing on fMRI: Correction for the confounding effects of vascular reactivity evaluated by joint fMRI and MEG in 335 adults.

PubMed

Tsvetanov, Kamen A; Henson, Richard N A; Tyler, Lorraine K; Davis, Simon W; Shafto, Meredith A; Taylor, Jason R; Williams, Nitin; Cam-Can; Rowe, James B

2015-06-01

In functional magnetic resonance imaging (fMRI) research one is typically interested in neural activity. However, the blood-oxygenation level-dependent (BOLD) signal is a composite of both neural and vascular activity. As factors such as age or medication may alter vascular function, it is essential to account for changes in neurovascular coupling when investigating neurocognitive functioning with fMRI. The resting-state fluctuation amplitude (RSFA) in the fMRI signal (rsfMRI) has been proposed as an index of vascular reactivity. The RSFA compares favourably with other techniques such as breath-hold and hypercapnia, but the latter are more difficult to perform in some populations, such as older adults. The RSFA is therefore a candidate for use in adjusting for age-related changes in vascular reactivity in fMRI studies. The use of RSFA is predicated on its sensitivity to vascular rather than neural factors; however, the extent to which each of these factors contributes to RSFA remains to be characterized. The present work addressed these issues by comparing RSFA (i.e., rsfMRI variability) to proxy measures of (i) cardiovascular function in terms of heart rate (HR) and heart rate variability (HRV) and (ii) neural activity in terms of resting state magnetoencephalography (rsMEG). We derived summary scores of RSFA, a sensorimotor task BOLD activation, cardiovascular function and rsMEG variability for 335 healthy older adults in the population-based Cambridge Centre for Ageing and Neuroscience cohort (Cam-CAN; www.cam-can.com). Mediation analysis revealed that the effects of ageing on RSFA were significantly mediated by vascular factors, but importantly not by the variability in neuronal activity. Furthermore, the converse effects of ageing on the rsMEG variability were not mediated by vascular factors. We then examined the effect of RSFA scaling of task-based BOLD in the sensorimotor task. The scaling analysis revealed that much of the effects of age on task-based activation studies with fMRI do not survive correction for changes in vascular reactivity, and are likely to have been overestimated in previous fMRI studies of ageing. The results from the mediation analysis demonstrate that RSFA is modulated by measures of vascular function and is not driven solely by changes in the variance of neural activity. Based on these findings we propose that the RSFA scaling method is articularly useful in large scale and longitudinal neuroimaging studies of ageing, or with frail participants, where alternative measures of vascular reactivity are impractical. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Effect of maternal age on the risk of preterm birth: A large cohort study

PubMed Central

Monet, Barbara; Ducruet, Thierry; Chaillet, Nils; Audibert, Francois

2018-01-01

Background Maternal age at pregnancy is increasing worldwide as well as preterm birth. However, the association between prematurity and advanced maternal age remains controversial. Objective To evaluate the impact of maternal age on the occurrence of preterm birth after controlling for multiple known confounders in a large birth cohort. Study design Retrospective cohort study using data from the QUARISMA study, a large Canadian randomized controlled trial, which collected data from 184,000 births in 32 hospitals. Inclusion criteria were maternal age over 20 years. Exclusion criteria were multiple pregnancy, fetal malformation and intra-uterine fetal death. Five maternal age categories were defined and compared for maternal characteristics, gestational and obstetric complications, and risk factors for prematurity. Risk factors for preterm birth <37 weeks, either spontaneous or iatrogenic, were evaluated for different age groups using multivariate logistic regression. Results 165,282 births were included in the study. Chronic hypertension, assisted reproduction techniques, pre-gestational diabetes, invasive procedure in pregnancy, gestational diabetes and placenta praevia were linearly associated with increasing maternal age whereas hypertensive disorders of pregnancy followed a “U” shaped distribution according to maternal age. Crude rates of preterm birth before 37 weeks followed a “U” shaped curve with a nadir at 5.7% for the group of 30–34 years. In multivariate analysis, the adjusted odds ratio (aOR) of prematurity stratified by age group followed a “U” shaped distribution with an aOR of 1.08 (95%CI; 1.01–1.15) for 20–24 years, and 1.20 (95% CI; 1.06–1.36) for 40 years and older. Confounders found to have the greatest impact were placenta praevia, hypertensive complications, and maternal medical history. Conclusion Even after adjustment for confounders, advanced maternal age (40 years and over) was associated with preterm birth. A maternal age of 30–34 years was associated with the lowest risk of prematurity. PMID:29385154

Effect of maternal age on the risk of preterm birth: A large cohort study.

PubMed

Fuchs, Florent; Monet, Barbara; Ducruet, Thierry; Chaillet, Nils; Audibert, Francois

2018-01-01

Maternal age at pregnancy is increasing worldwide as well as preterm birth. However, the association between prematurity and advanced maternal age remains controversial. To evaluate the impact of maternal age on the occurrence of preterm birth after controlling for multiple known confounders in a large birth cohort. Retrospective cohort study using data from the QUARISMA study, a large Canadian randomized controlled trial, which collected data from 184,000 births in 32 hospitals. Inclusion criteria were maternal age over 20 years. Exclusion criteria were multiple pregnancy, fetal malformation and intra-uterine fetal death. Five maternal age categories were defined and compared for maternal characteristics, gestational and obstetric complications, and risk factors for prematurity. Risk factors for preterm birth <37 weeks, either spontaneous or iatrogenic, were evaluated for different age groups using multivariate logistic regression. 165,282 births were included in the study. Chronic hypertension, assisted reproduction techniques, pre-gestational diabetes, invasive procedure in pregnancy, gestational diabetes and placenta praevia were linearly associated with increasing maternal age whereas hypertensive disorders of pregnancy followed a "U" shaped distribution according to maternal age. Crude rates of preterm birth before 37 weeks followed a "U" shaped curve with a nadir at 5.7% for the group of 30-34 years. In multivariate analysis, the adjusted odds ratio (aOR) of prematurity stratified by age group followed a "U" shaped distribution with an aOR of 1.08 (95%CI; 1.01-1.15) for 20-24 years, and 1.20 (95% CI; 1.06-1.36) for 40 years and older. Confounders found to have the greatest impact were placenta praevia, hypertensive complications, and maternal medical history. Even after adjustment for confounders, advanced maternal age (40 years and over) was associated with preterm birth. A maternal age of 30-34 years was associated with the lowest risk of prematurity.

Socioeconomics and Major Disabilities: Characteristics of Working-Age Adults in Rwanda.

PubMed

Kiregu, Joshua; Murindahabi, Nathalie K; Tumusiime, David; Thomson, Dana R; Hedt-Gauthier, Bethany L; Ahayo, Anita

2016-01-01

Disability affects approximately 15% of the world's population, and has adverse socio-economic effects, especially for the poor. In Rwanda, there are a number of government compensation programs that support the poor, but not specifically persons with disability (PWDs). This study investigates the relationship between poverty and government compensation on disability among working-age adults in Rwanda. This was a secondary analysis of 35,114 adults aged 16 to 65 interviewed in the 2010/2011 Rwanda Household Wealth and Living Conditions survey, a national cross-sectional two-stage cluster survey, stratified by district. This study estimated self-reported major disability, and used chi-square tests to estimate associations (p<0.1) with income, government compensation, occupation type, participation in public works programs, and household poverty status. Non-collinear economic variables were included in a multivariate logistic regression, along with socio-demographic confounders that modified the relationship between any economic predictor and the outcome by 10% or more. All analyses adjusted for sampling weights, stratification, and clustering of households. Over 4% of working-age adults reported having a major disability and the most prevalent types of disability in order were physical, mental, and then sensory disability. In bivariate analysis, annual income, occupation type, and poverty status were associated with major disability (p<0.001 for all). Occupation type was dropped because it was collinear with income. Age, education, and urban/rural residence were confounders. In the multivariate analysis, adults in all income groups had about half the odds of disability compared to adults with no income (Rwf1-120,000 OR = 0.57; Rwf120,000-250,000 OR = 0.61; Rwf250,000-1,000,000 OR = 0.59; Rwf1,000,000+ OR = 0.66; p<0.05 for all), and non-poor adults had 0.77 the odds of disability compared to poor adults (p = 0.001). Given that personal income rather than government programming is associated with disability in Rwanda, we recommend deliberately targeted services to those with disability via cash transfers, placements in disability-appropriate employment, and micro-savings programs.

Socioeconomics and Major Disabilities: Characteristics of Working-Age Adults in Rwanda

PubMed Central

Kiregu, Joshua; Murindahabi, Nathalie K.; Tumusiime, David; Thomson, Dana R.; Hedt-Gauthier, Bethany L.; Ahayo, Anita

2016-01-01

Background Disability affects approximately 15% of the world’s population, and has adverse socio-economic effects, especially for the poor. In Rwanda, there are a number of government compensation programs that support the poor, but not specifically persons with disability (PWDs). This study investigates the relationship between poverty and government compensation on disability among working-age adults in Rwanda. Methods This was a secondary analysis of 35,114 adults aged 16 to 65 interviewed in the 2010/2011 Rwanda Household Wealth and Living Conditions survey, a national cross-sectional two-stage cluster survey, stratified by district. This study estimated self-reported major disability, and used chi-square tests to estimate associations (p<0.1) with income, government compensation, occupation type, participation in public works programs, and household poverty status. Non-collinear economic variables were included in a multivariate logistic regression, along with socio-demographic confounders that modified the relationship between any economic predictor and the outcome by 10% or more. All analyses adjusted for sampling weights, stratification, and clustering of households. Results Over 4% of working-age adults reported having a major disability and the most prevalent types of disability in order were physical, mental, and then sensory disability. In bivariate analysis, annual income, occupation type, and poverty status were associated with major disability (p<0.001 for all). Occupation type was dropped because it was collinear with income. Age, education, and urban/rural residence were confounders. In the multivariate analysis, adults in all income groups had about half the odds of disability compared to adults with no income (Rwf1-120,000 OR = 0.57; Rwf120,000–250,000 OR = 0.61; Rwf250,000–1,000,000 OR = 0.59; Rwf1,000,000+ OR = 0.66; p<0.05 for all), and non-poor adults had 0.77 the odds of disability compared to poor adults (p = 0.001). Conclusion Given that personal income rather than government programming is associated with disability in Rwanda, we recommend deliberately targeted services to those with disability via cash transfers, placements in disability-appropriate employment, and micro-savings programs. PMID:27101377

Increased incidence of preeclampsia in mothers of advanced age conceiving by oocyte donation.

PubMed

Dior, Uri P; Laufer, Neri; Chill, Henry H; Granovsky-Grisaru, Sorina; Yagel, Simcha; Yaffe, Haim; Gielchinsky, Yuval

2018-05-01

The aim of this study was to evaluate the risk of preeclampsia in women of advanced age who conceived through donated oocytes as compared with natural conceptions. A historical prospective study of singleton live births of parturients ≥ 45 years of age at four university hospitals was conducted. For the purpose of the study, the population was divided by the mode of conception into two groups: oocyte donation and natural conception. The main outcome variable in this study was preeclampsia. Secondary outcomes included pregnancy-induced hypertension and Small for Gestational Age. Two hundred and seventy pregnancies were achieved naturally and 135 women conceived by oocyte donation. Mean age at delivery for the natural conception and oocyte donation groups was 45.7 and 47.8, respectively. Preeclampsia complicated 3 out of 270 (1.1%) natural conception pregnancies and 17 out of 135 (12.6%) oocyte donation conceptions. After adjusting for confounders, oocyte donation pregnancies were found to be associated with a 12-fold increased risk for preeclampsia (P = 0.001). Among oocyte donation pregnancies, the risk of preeclampsia was not affected by parity or age. A substantially increased risk for preeclampsia was found in oocyte donation pregnancies, suggesting that the foreign oocyte may play a specific biologic role in the development of preeclampsia after the age of 45.

Child development at 5 years of age predicted mathematics ability and schooling outcomes in Malawian adolescents.

PubMed

Gandhi, Mihir; Teivaanmaki, Tiina; Maleta, Kenneth; Duan, Xiaolian; Ashorn, Per; Cheung, Yin Bun

2013-01-01

This study aimed to examine the association between child development at 5 years of age and mathematics ability and schooling outcomes at 12 years of age in Malawian children. A prospective cohort study looking at 609 rural Malawian children. Outcome measures were percentage of correctly answered mathematics questions, highest school grade completed and number of times repeating school grades at 12 years of age. A child development summary score obtained at 5 years of age was the main exposure variable. Regression analyses were used to estimate the association and adjust for confounders. Sensitivity analysis was performed by handling losses to follow-up with multiple imputation (MI) method. The summary score was positively associated with percentage of correctly answered mathematics questions (p = 0.057; p = 0.031 MI) and with highest school grade completed (p = 0.096; p = 0.070 MI), and negatively associated with number of times repeating school grades (p = 0.834; p = 0.339 MI). Fine motor score at 5 years was independently associated with the mathematic score (p = 0.032; p = 0.011 MI). The association between child development and mathematics ability did not depend on school attendance. Child development at 5 years of age showed signs of positive association with mathematics ability and possibly with highest school grade completed at 12 years of age. © 2012 The Author(s)/Acta Paediatrica © 2012 Foundation Acta Paediatrica.

The effect of alcohol, tobacco and caffeine consumption and vegetarian diet on gallstone prevalence.

PubMed

Walcher, Thomas; Haenle, Mark Martin; Mason, Richard Andrew; Koenig, Wolfgang; Imhof, Armin; Kratzer, Wolfgang

2010-11-01

To investigate the effects of alcohol, tobacco and caffeine consumption and of vegetarian diet on gallstone prevalence in an urban population sample. A total of 2417 individuals underwent ultrasound examination and completed a standardized questionnaire as part of the EMIL study. Statistical analysis of the data considered the known risk factors of age, female sex, BMI, positive family history and potential confounders, such as alcohol, caffeine and tobacco consumption and vegetarian diet using multiple logistic regression with variable selection. The prevalence of gallstones in the population sample was 8% (171 out of 2147). Findings of the study confirmed the classic risk factors of age, female sex, obesity and positive family history. After the variable selection of potential risk factors in a logistic regression that was adjusted for age, female sex, BMI and positive family history, the factors like tobacco [odds ratio (OR) 1.09, 95% confidence interval (CI): 0.76-1.56, P=0.64] and caffeine consumption (OR: 0.77, 95% CI: 0.42-1.42, P=0.40) as well as vegetarian diet (OR: 1.14, 95% CI: 0.39-3.35, P=0.81) had no effect on gallstone prevalence. A protective effect against development of gallstones was shown for alcohol consumption (OR: 0.67, 95% CI: 0.46-0.99, P=0.04). The factors like tobacco and caffeine consumption as well as vegetarian diet exerted no measurable effect on the prevalence of gallstones. A protective effect was found for alcohol consumption.

Dietary fiber is positively associated with cognitive control among prepubertal children.

PubMed

Khan, Naiman A; Raine, Lauren B; Drollette, Eric S; Scudder, Mark R; Kramer, Arthur F; Hillman, Charles H

2015-01-01

Converging evidence now indicates that aerobic fitness and adiposity are key correlates of childhood cognitive function and brain health. However, the evidence relating dietary intake to executive function/cognitive control remains limited. The current study assessed cross-sectional associations between performance on an attentional inhibition task and dietary fatty acids (FAs), fiber, and overall diet quality among children aged 7-9 y (n = 65). Attentional inhibition was assessed by using a modified flanker task. Three-day food records were used to conduct nutrient-level analyses and to calculate diet quality (Healthy Eating Index-2005) scores. Bivariate correlations revealed that socioeconomic status and sex were not related to task performance or diet measures. However, age, intelligence quotient (IQ), pubertal staging, maximal oxygen uptake (V̇O2max), and percentage of fat mass (%fat mass) correlated with task accuracy. Hierarchical regression models were used to determine the relation between diet variables and task accuracy and reaction time across both congruent and incongruent trials of the flanker task. After adjustment of confounding variables (age, IQ, pubertal staging, V̇O2max, and %fat mass), congruent accuracy was positively associated with insoluble fiber (β = 0.26, P = 0.03) and total dietary fiber (β = 0.23, P = 0.05). Incongruent response accuracy was positively associated with insoluble fiber (β = 0.35, P < 0.01), pectins (β = 0.25, P = 0.04), and total dietary fiber (β = 0.32, P < 0.01). Higher diet quality was related to lower accuracy interference (β = -0.26, P = 0.03), whereas higher total FA intake was related to greater accuracy interference (β = 0.24, P = 0.04). No statistically significant associations were observed between diet variables and reaction time measures. These results demonstrate that children's diet quality, specifically dietary fiber, is an important correlate of performance on a cognitive task requiring variable amounts of cognitive control. © 2015 American Society for Nutrition.

Dietary Fiber Is Positively Associated with Cognitive Control among Prepubertal Children12

PubMed Central

Khan, Naiman A; Raine, Lauren B; Drollette, Eric S; Scudder, Mark R; Kramer, Arthur F; Hillman, Charles H

2015-01-01

Background: Converging evidence now indicates that aerobic fitness and adiposity are key correlates of childhood cognitive function and brain health. However, the evidence relating dietary intake to executive function/cognitive control remains limited. Objective: The current study assessed cross-sectional associations between performance on an attentional inhibition task and dietary fatty acids (FAs), fiber, and overall diet quality among children aged 7–9 y (n = 65). Methods: Attentional inhibition was assessed by using a modified flanker task. Three-day food records were used to conduct nutrient-level analyses and to calculate diet quality (Healthy Eating Index–2005) scores. Results: Bivariate correlations revealed that socioeconomic status and sex were not related to task performance or diet measures. However, age, intelligence quotient (IQ), pubertal staging, maximal oxygen uptake (V̇O2max), and percentage of fat mass (%fat mass) correlated with task accuracy. Hierarchical regression models were used to determine the relation between diet variables and task accuracy and reaction time across both congruent and incongruent trials of the flanker task. After adjustment of confounding variables (age, IQ, pubertal staging, V̇O2max, and %fat mass), congruent accuracy was positively associated with insoluble fiber (β = 0.26, P = 0.03) and total dietary fiber (β = 0.23, P = 0.05). Incongruent response accuracy was positively associated with insoluble fiber (β = 0.35, P < 0.01), pectins (β = 0.25, P = 0.04), and total dietary fiber (β = 0.32, P < 0.01). Higher diet quality was related to lower accuracy interference (β = −0.26, P = 0.03), whereas higher total FA intake was related to greater accuracy interference (β = 0.24, P = 0.04). No statistically significant associations were observed between diet variables and reaction time measures. Conclusion: These results demonstrate that children’s diet quality, specifically dietary fiber, is an important correlate of performance on a cognitive task requiring variable amounts of cognitive control. PMID:25527669

Missing variables: how exclusion of human resources policy information confounds research connecting health and business outcomes.

PubMed

Lynch, Wendy D; Sherman, Bruce W

2014-01-01

When corporate health researchers examine the effects of health on business outcomes or the effect of health interventions on health and business outcomes, results will necessarily be confounded by the corporate environment(s) in which they are studied. In this research setting, most studies control for factors traditionally identified in public health, such as demographics and health status. Nevertheless, often overlooked is the extent to which company policies can also independently impact health care cost, work attendance, and productivity outcomes. With changes in employment and benefits practices resulting from health care reform, including incentives and plan design options, consideration of these largely neglected variables in research design has become increasingly important. This commentary summarizes existing knowledge regarding the implications of policy variations in research outcomes and provides a framework for incorporating them into future employer-based research.

Instrumental variable methods in comparative safety and effectiveness research.

PubMed

Brookhart, M Alan; Rassen, Jeremy A; Schneeweiss, Sebastian

2010-06-01

Instrumental variable (IV) methods have been proposed as a potential approach to the common problem of uncontrolled confounding in comparative studies of medical interventions, but IV methods are unfamiliar to many researchers. The goal of this article is to provide a non-technical, practical introduction to IV methods for comparative safety and effectiveness research. We outline the principles and basic assumptions necessary for valid IV estimation, discuss how to interpret the results of an IV study, provide a review of instruments that have been used in comparative effectiveness research, and suggest some minimal reporting standards for an IV analysis. Finally, we offer our perspective of the role of IV estimation vis-à-vis more traditional approaches based on statistical modeling of the exposure or outcome. We anticipate that IV methods will be often underpowered for drug safety studies of very rare outcomes, but may be potentially useful in studies of intended effects where uncontrolled confounding may be substantial.

Male fertility: psychiatric considerations.

PubMed

Hall, Elise; Burt, Vivien K

2012-02-01

To examine: 1) current knowledge on normal biologic variation of seminal parameters; 2) how stress and psychological factors affect sperm quality in fertile and infertile males; and 3) how mental illness and psychopharmacologic agents can affect male fertility. English-language Medline, Embase, and Psycinfo were searched for relevant publications (from 1970 to January 2011) for systematic review. None. None. None. Possible effects of stress, mood, and psychotropic medications on male factor fertility. Male-factor infertility is influenced by myriad factors (obesity, tobacco, etc.). Stress alone may reduce testosterone levels and spermatogenesis. Infertility assessment and treatment can lead to distress and negatively affect sperm samples. Available research has failed to control for potentially confounding variables. Although some trends have been identified, larger-scale studies that adequately control all confounding variables are needed before conclusions can be made about the relationship between stress, psychotropic agents, and male infertility. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Controlling for seasonal patterns and time varying confounders in time-series epidemiological models: a simulation study.

PubMed

Perrakis, Konstantinos; Gryparis, Alexandros; Schwartz, Joel; Le Tertre, Alain; Katsouyanni, Klea; Forastiere, Francesco; Stafoggia, Massimo; Samoli, Evangelia

2014-12-10

An important topic when estimating the effect of air pollutants on human health is choosing the best method to control for seasonal patterns and time varying confounders, such as temperature and humidity. Semi-parametric Poisson time-series models include smooth functions of calendar time and weather effects to control for potential confounders. Case-crossover (CC) approaches are considered efficient alternatives that control seasonal confounding by design and allow inclusion of smooth functions of weather confounders through their equivalent Poisson representations. We evaluate both methodological designs with respect to seasonal control and compare spline-based approaches, using natural splines and penalized splines, and two time-stratified CC approaches. For the spline-based methods, we consider fixed degrees of freedom, minimization of the partial autocorrelation function, and general cross-validation as smoothing criteria. Issues of model misspecification with respect to weather confounding are investigated under simulation scenarios, which allow quantifying omitted, misspecified, and irrelevant-variable bias. The simulations are based on fully parametric mechanisms designed to replicate two datasets with different mortality and atmospheric patterns. Overall, minimum partial autocorrelation function approaches provide more stable results for high mortality counts and strong seasonal trends, whereas natural splines with fixed degrees of freedom perform better for low mortality counts and weak seasonal trends followed by the time-season-stratified CC model, which performs equally well in terms of bias but yields higher standard errors. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of anesthesia on the cerebral capillary blood flow in young and old mice

NASA Astrophysics Data System (ADS)

Moeini, Mohammad; Tabatabaei, Maryam S.; Bélanger, Samuel; Avti, Pramod; Castonguay, Alexandre; Pouliot, Philippe; Lesage, Frédéric

2015-03-01

Despite recent findings on the possible role of age-related cerebral microvasculature changes in cognition decline, previous studies of capillary blood flow in aging (using animal models) are scarce and limited to anesthetized conditions. Since anesthesia can have different effects in young and old animals, it may introduce a confounding effect in aging studies. The present study aimed to eliminate the potential confound introduced by anesthesia by measuring capillary blood flow parameters in both awake conditions and under isoflurane anesthesia. We used 2-photon laser scanning fluorescence microscopy to measure capillary diameter, red blood cell velocity and flux, hematocrit and capillary volumetric flow in individual capillaries in the barrel cortex of 6- and 24-month old C57Bl/6 mice. It was observed that microvascular properties are significantly affected by anesthesia leading to different trends in capillary blood flow parameters with aging when measured under awake or anesthetized conditions. The findings in this study suggest taking extra care in interpreting aging studies from anesthetized animals.

Why does early sexual intercourse predict subsequent maladjustment? Exploring potential familial confounds.

PubMed

Donahue, Kelly L; Lichtenstein, Paul; Långström, Niklas; D'Onofrio, Brian M

2013-02-01

Previous studies have found an association between early age at first sexual intercourse and subsequent psychosocial maladjustment. Using a quasi-experimental approach, we examined the extent to which this observed association may be due to familial confounds not explored in prior research. Using a population-based cohort of Swedish adult twins (ages 19-47; N = 12,126), we examined the nature of the association between early sexual intercourse (i.e., first intercourse occurring before age 16) and various outcomes reflecting psychosocial health, including substance use, depression, criminal convictions, and adolescent childbearing. We used two methods--discordant-twin analyses and bivariate twin modeling--to estimate the extent to which genetic and environmental confounds explained observed associations. Individuals who engaged in early intercourse were at greater risk for most of the adverse psychosocial health outcomes measured in this study. However, twin pairs discordant for engaging in early intercourse did not differ significantly in their risk for psychosocial maladjustment. Our results indicated that early age at first sexual intercourse and subsequent psychosocial maladjustment may be associated because of familial factors shared by twins. Early intercourse may be associated with poor psychosocial health largely due to shared familial influences rather than through a direct causal connection. Therefore, effective and efficient interventions should address other risk factors common to early intercourse and poor psychosocial health.

Insulin-Like Growth Factor-1 Bioactivity Plays a Prosurvival Role in Older Participants

PubMed Central

2013-01-01

The aim of this study was to address the intriguing issue of the role of the insulin-like growth factor (IGF)-1 system in longevity looking at the role of different components of IGF system. Vital status was ascertained in 1,197 men and women aged greater than or equal to 65 years from the InCHIANTI study. Hormonal levels were categorized into quartiles, and ratio of IGF-1 to IGF-binding protein (IGFBP)-1 was calculated. The relationship between hormones and mortality was tested by Cox proportional hazard models adjusted for age, sex, and confounders. During the 8-year follow-up period, 240 died and 957 survived. Lowest quartiles of IGF-1 and IGFBP-1 were considered as reference. Compared with the lowest quartiles, IGF-1 in upper quartiles was a negative predictor of mortality independent of age and sex (p = .01) but not independent of IGFBP-1 and other confounders. IGFBP-1 in second–third quartiles was negatively associated and that in the fourth quartiles was positively associated with risk of death. IGF-1/IGFBP-1 ratio in the lowest quartiles was a strong positive predictor of mortality, in age- and sex-adjusted model (p = .005), and independent of additional confounders (p = .037). High IGFBP-1 and low IGF-1/IGFBP-1 ratio are associated with all-cause mortality in older population. PMID:23671288

Insulin-like growth factor-1 bioactivity plays a prosurvival role in older participants.

PubMed

Maggio, Marcello; Cattabiani, Chiara; Lauretani, Fulvio; Bandinelli, Stefania; De Vita, Francesca; Dall'Aglio, Elisabetta; Corsonello, Andrea; Lattanzio, Fabrizia; Paolisso, Giuseppe; Ferrucci, Luigi; Ceda, Gian Paolo

2013-11-01

The aim of this study was to address the intriguing issue of the role of the insulin-like growth factor (IGF)-1 system in longevity looking at the role of different components of IGF system. Vital status was ascertained in 1,197 men and women aged greater than or equal to 65 years from the InCHIANTI study. Hormonal levels were categorized into quartiles, and ratio of IGF-1 to IGF-binding protein (IGFBP)-1 was calculated. The relationship between hormones and mortality was tested by Cox proportional hazard models adjusted for age, sex, and confounders. During the 8-year follow-up period, 240 died and 957 survived. Lowest quartiles of IGF-1 and IGFBP-1 were considered as reference. Compared with the lowest quartiles, IGF-1 in upper quartiles was a negative predictor of mortality independent of age and sex (p = .01) but not independent of IGFBP-1 and other confounders. IGFBP-1 in second-third quartiles was negatively associated and that in the fourth quartiles was positively associated with risk of death. IGF-1/IGFBP-1 ratio in the lowest quartiles was a strong positive predictor of mortality, in age- and sex-adjusted model (p = .005), and independent of additional confounders (p = .037). High IGFBP-1 and low IGF-1/IGFBP-1 ratio are associated with all-cause mortality in older population.

Frailty among rural elderly adults

PubMed Central

2014-01-01

Background This study aimed to estimate the prevalence and associated factors related to frailty, by Fried criteria, in the elderly population in a rural area in the Andes Mountains, and to analyze the relationship of these with comorbidity and disability. Methods A cross-sectional study was undertaken involving 1878 participants 60 years of age and older. The frailty syndrome was diagnosed based on the Fried criteria (weakness, low speed, low physical activity, exhaustion, and weight loss). Variables were grouped as theoretical domains and, along with other potential confounders, were placed into five categories: (a) demographic and socioeconomic status, (b) health status, (c) self-reported functional status, (d) physical performance-based measures, and (e) psychosocial factors. Chi-square, ANOVA, and multinomial logistic regression analyses were used to test the prognostic value of frailty for the outcomes of interest. Results The prevalence of frailty was 12.2%. Factors associated with frailty were age, gender, health status variables that included self-perceived health and number of chronic conditions, functional covariate variables that included disability in activities in daily living (ADL), disabilities in instrumental ADL, chair stand time, and psychosocial variables that included depressive symptoms and cognitive impairment. Higher comorbidity and disability was found in frail elderly people. Only a subset of frail elderly people (10%) reported no disease or disability. Conclusions A relevant number of elderly persons living in rural areas in the Andes Mountains are frail. The prevalence of frailty is similar to that reported in other populations in the Latin American region. Our results support the use of modified Cardiovascular Health Study criteria to measure frailty in communities other than urban settings. Frailty in this study was strongly associated with comorbidities, and frailty and comorbidity predicted disability. PMID:24405584

Socioeconomic factors and effect of evidence-based patient information about primary prevention of type 2 diabetes mellitus--are there interactions?

PubMed

Genz, Jutta; Haastert, Burkhard; Müller, Hardy; Verheyen, Frank; Cole, Dennis; Rathmann, Wolfgang; Nowotny, Bettina; Roden, Michael; Giani, Guido; Ohmann, Christian; Icks, Andrea

2014-08-18

Having shown in a recent randomized controlled trial that evidence-based patient information (EBPI) significantly increased knowledge on primary prevention of diabetes compared to standard patient information, we now investigated interaction between socioeconomic status (SES) and the effect of an EBPI. 1,120 visitors (aged 40-70 years, without known diabetes) to the "Techniker Krankenkasse" and the "German Diabetes Center" websites were randomized. The intervention group received a newly developed on-line EBPI, the control group standard on-line information. The primary outcome measure was knowledge, classified as "good/average/poor". We analyzed associations of knowledge with socioeconomic variables (education, vocational training, employment, subjective social status) combined with intervention effect including interactions, adjusted for possible confounding by knowledge before intervention, self-reported blood glucose measurements, blood pressure, blood lipid levels, age and gender. Logistic regression models were fitted to the subpopulation (n = 647) with complete values in these variables.Education (high vs. low) was significantly associated with knowledge (good vs. average/poor); however, there was no significant interaction between education and intervention. After adjustment, the other socioeconomic variables were not significantly associated with knowledge. Socioeconomic variables did not significantly change the effect of the intervention. There was a tendency towards a lower effect where lower educated individuals were concerned. Possibly the power was too low to detect interaction effects. Larger studies using SES-specific designs are needed to clarify the effect of SES. We suggest considering the socioeconomic status when evaluating a decision aid, e.g. an EBPI, to ensure its effectiveness not only in higher socioeconomic groups. Current Controlled Trials ISRCTN22060616 (Date assigned: 12 September 2008).

Reporting of research quality characteristics of studies published in 6 major clinical dental specialty journals.

PubMed

Pandis, Nikolaos; Polychronopoulou, Argy; Madianos, Phoebus; Makou, Margarita; Eliades, Theodore

2011-06-01

The objective of this article was to record reporting characteristics related to study quality of research published in major specialty dental journals with the highest impact factor (Journal of Endodontics, Journal of Oral and Maxillofacial Surgery, American Journal of Orthodontics and Dentofacial Orthopedics; Pediatric Dentistry, Journal of Clinical Periodontology, and International Journal of Prosthetic Dentistry). The included articles were classified into the following 3 broad subject categories: (1) cross-sectional (snap-shot), (2) observational, and (3) interventional. Multinomial logistic regression was conducted for effect estimation using the journal as the response and randomization, sample calculation, confounding discussed, multivariate analysis, effect measurement, and confidence intervals as the explanatory variables. The results showed that cross-sectional studies were the dominant design (55%), whereas observational investigations accounted for 13%, and interventions/clinical trials for 32%. Reporting on quality characteristics was low for all variables: random allocation (15%), sample size calculation (7%), confounding issues/possible confounders (38%), effect measurements (16%), and multivariate analysis (21%). Eighty-four percent of the published articles reported a statistically significant main finding and only 13% presented confidence intervals. The Journal of Clinical Periodontology showed the highest probability of including quality characteristics in reporting results among all dental journals. Copyright © 2011 Elsevier Inc. All rights reserved.

Fiber typing in aging muscle.

PubMed

Purves-Smith, Fennigje M; Sgarioto, Nicolas; Hepple, Russell T

2014-04-01

It is accepted widely that fast-twitch muscle fibers are preferentially impacted in aging muscle, yet we hypothesize that this is not valid when aging muscle atrophy becomes severe. In this review, we summarize the evidence of fiber type-specific effect in aging muscle and the potential confounding roles of fibers coexpressing multiple myosin heavy-chain isoforms and their histochemical identification.

Success Providing Postpartum Intrauterine Devices in Private-Sector Health Care Facilities in Nigeria: Factors Associated With Uptake.

PubMed

Eluwa, George Ie; Atamewalen, Ronke; Odogwu, Kingsley; Ahonsi, Babatunde

2016-06-20

Use of modern contraceptive methods in Nigeria remained at 10% between 2008 and 2013 despite substantive investments in family planning services. Many women in their first postpartum year, in particular, have an unmet need for family planning. We evaluated use of postpartum intrauterine device (IUD) insertion and determined factors associated with its uptake in Nigeria. Data were collected between May 2014 and February 2015 from 11 private health care facilities in 6 southern Nigerian states. Women attending antenatal care in participating facilities were counseled on all available contraceptive methods including the postpartum IUD. Data were abstracted from participating facility records and evaluated using a cross-sectional analysis. Categorical variables were calculated as proportions while continuous variables were calculated as medians with the associated interquartile range (IQR). Multivariate logistic regression analysis was used to identify factors associated with uptake of the postpartum IUD while controlling for potential confounding factors, including age, educational attainment, marital status, parity, number of living children, and previous use of contraception. During the study period, 728 women delivered in the 11 facilities. The median age was 28 years, and most women were educated (73% had completed at least the secondary level). The majority (96%) of the women reported they were married, and the median number of living children was 3 (IQR, 2-4). Uptake of the postpartum IUD was 41% (n = 300), with 8% (n = 25) of the acceptors experiencing expulsion of the IUD within 6 weeks post-insertion. After controlling for potential confounding factors, several characteristics were associated with greater likelihood of choosing the postpartum IUD, including lower education, having a higher number of living children, and being single. Women who had used contraceptives previously were less likely to choose the postpartum IUD than women who had not previously used contraception (adjusted odds ratio, 0.68; 95% confidence interval, 0.55 to 0.84). A high percentage (41%) of women delivering in private health care facilities in southern Nigeria accepted immediate postpartum IUD insertion. Scale-up of postpartum IUD services is a promising approach to increasing uptake of long-acting reversible contraceptives among women in Nigeria. © Eluwa et al.

The role of sex and body weight on the metabolic effects of high-fat diet in C57BL/6N mice

PubMed Central

Ingvorsen, C; Karp, N A; Lelliott, C J

2017-01-01

Background: Metabolic disorders are commonly investigated using knockout and transgenic mouse models on the C57BL/6N genetic background due to its genetic susceptibility to the deleterious metabolic effects of high-fat diet (HFD). There is growing awareness of the need to consider sex in disease progression, but limited attention has been paid to sexual dimorphism in mouse models and its impact in metabolic phenotypes. We assessed the effect of HFD and the impact of sex on metabolic variables in this strain. Methods: We generated a reference data set encompassing glucose tolerance, body composition and plasma chemistry data from 586 C57BL/6N mice fed a standard chow and 733 fed a HFD collected as part of a high-throughput phenotyping pipeline. Linear mixed model regression analysis was used in a dual analysis to assess the effect of HFD as an absolute change in phenotype, but also as a relative change accounting for the potential confounding effect of body weight. Results: HFD had a significant impact on all variables tested with an average absolute effect size of 29%. For the majority of variables (78%), the treatment effect was modified by sex and this was dominated by male-specific or a male stronger effect. On average, there was a 13.2% difference in the effect size between the male and female mice for sexually dimorphic variables. HFD led to a significant body weight phenotype (24% increase), which acts as a confounding effect on the other analysed variables. For 79% of the variables, body weight was found to be a significant source of variation, but even after accounting for this confounding effect, similar HFD-induced phenotypic changes were found to when not accounting for weight. Conclusion: HFD and sex are powerful modifiers of metabolic parameters in C57BL/6N mice. We also demonstrate the value of considering body size as a covariate to obtain a richer understanding of metabolic phenotypes. PMID:28394359

Insulin resistance and cognitive test performance in elderly adults: National health and nutrition examination survey (NHANES).

PubMed

Sherzai, Ayesha Z; Shaheen, Magda; Yu, Jeffrey J; Talbot, Konrad; Sherzai, Dean

2018-05-15

To examine the relationship between homeostatic model of insulin resistance (HOMA-IR) and cognitive test performance among population≥60years in a national database. Higher insulin resistance is associated with lower cognitive test performance score in the population≥60years. We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 and 2001-2002. Cognitive test performance was measured by the Digit Symbol Substitution (DSS) exercise score. The main independent variable was the homeostasis model assessment of insulin resistance (HOMA-IR). We used bivariate analysis and generalized linear model adjusting for age, gender, race, education, body mass index, and systolic and diastolic blood pressures; total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL) and triglyceride levels; and physical activity, diabetes mellitus, stroke, and congestive heart failure. STATA 14 was used to analyze the data taking into consideration the design, strata and weight. Of the 1028 participants, 44% were male and 85% were white. The mean age was 70.0±0.28 (SE) years. Their average HOMA-IR was 3.6±0.14 and they had a mean of 49.2±0.8 correct DSS score in the cognitive test. Adjusting for the confounding variables, HOMA-IR was associated with decline in DSS score (B=-0.30, 95% confidence interval=-0.54 and -0.05, p=0.01). The model explained 44% of the variability of the DSS score (R 2 =0.44). Significant predictors of decline in DSS score were age, gender, race, and education (p=0.01). Insulin resistance as measured by HOMA-IR was independently associated with lower cognitive test performance score among elderly participants aged ≥60years. Longitudinal studies are needed to test the mechanism and the causal relationship. Copyright © 2017. Published by Elsevier B.V.

[Lower lymphocyte response in severe cases of acute bronchiolitis due to respiratory syncytial virus].

PubMed

Ramos-Fernández, José Miguel; Moreno-Pérez, David; Antúnez-Fernández, Cristina; Milano-Manso, Guillermo; Cordón-Martínez, Ana María; Urda-Cardona, Antonio

2018-06-01

Acute bronchiolitis (AB) of the infant has a serious outcome in 6-16% of the hospital admitted cases. Its pathogenesis and evolution is related to the response of the T lymphocytes. The objective of the present study is to determine if the lower systemic lymphocytic response is related to a worse outcome of AB in hospitalised infants. Retrospective observational-analytical study of cases-controls nested in a cohort of patients admitted due to RSV-AB between the period from October 2010 to March 2015. Those with a full blood count in the first 48hours of respiratory distress were included. Infants with underlying disease, bacterial superinfection, and premature infants <32 weeks of gestation were excluded. The main dichotomous variable was PICU admission. Other variables were: gender, age, post-menstrual age, gestational and post-natal tobacco exposure, admission month, type of lactation, and days of onset of respiratory distress. Lymphocyte counts were categorised by quartiles. Bivariate analysis was performed with the main variable and then by logistic regression to analyse confounding factors. The study included 252 infants, of whom 6.6% (17) required PICU admission. The difference in mean±SD of lymphocytes for patients admitted to and not admitted to PICU was 4,044±1755 and 5,035±1786, respectively (Student-t test, P<.05). An association was found between PICU admission and lymphocyte count <3700/ml (Chi-squared, P=.019; OR: 3.2) and it was found to be maintained in the logistic regression, regardless of age and all other studied factors (Wald 4.191 P=.041, OR: 3.8). A relationship was found between lymphocytosis <3700/ml in the first days of respiratory distress and a worse outcome in previously healthy infants <12 months and gestational age greater than 32 weeks with RSV-AB. Copyright © 2017 Asociación Española de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

Main biomarkers associated with age-related plasma zinc decrease and copper/zinc ratio in healthy elderly from ZincAge study.

PubMed

Giacconi, R; Costarelli, L; Piacenza, F; Basso, A; Rink, L; Mariani, E; Fulop, T; Dedoussis, G; Herbein, G; Provinciali, M; Jajte, J; Lengyel, I; Mocchegiani, E; Malavolta, M

2017-12-01

Zinc (Zn) plays an essential role in many biological processes including immune response. Impaired Zn status promotes immune dysfunction, and it has been associated with enhanced chronic inflammation during aging. It has been suggested that the measurement of circulating Zn by itself could not reflect the real Zn status of an individual. It is therefore necessary to identify other determinants associated with plasma Zn to better understanding how physiopathological conditions during aging may affect the concentration of this metal. We have investigated the association between Zn levels and some biomarkers in 1090 healthy elderly from five European countries to increase the accuracy in the assessment of the Zn status. Stepwise multivariate linear regression models were used to analyze the influence of factors such as age, dietary intake, inflammatory mediators, laboratory parameters and polymorphisms previously associated with Zn homeostasis. Plasma Zn decrement was most strongly predicted by age, while positive correlations were found with albumin, RANTES and Zn intake after adjustment for multiple confounders. HSP70 +1267 AA genotype was an independent factor associated with Zn plasma concentrations. Cu/Zn ratio was positively associated with markers of systemic inflammation and age and negatively associated with albumin serum levels. Our findings show the most important independent determinants of plasma Zn concentration and Cu/Zn ratio variability in elderly population and suggest that the decline with age of Zn circulating levels is more dependent on physiopathological changes occurring with aging rather than to its nutritional intake.

The effect of ageing on fMRI: Correction for the confounding effects of vascular reactivity evaluated by joint fMRI and MEG in 335 adults

PubMed Central

Henson, Richard N. A.; Tyler, Lorraine K.; Davis, Simon W.; Shafto, Meredith A.; Taylor, Jason R.; Williams, Nitin; Cam‐CAN; Rowe, James B.

2015-01-01

Abstract In functional magnetic resonance imaging (fMRI) research one is typically interested in neural activity. However, the blood‐oxygenation level‐dependent (BOLD) signal is a composite of both neural and vascular activity. As factors such as age or medication may alter vascular function, it is essential to account for changes in neurovascular coupling when investigating neurocognitive functioning with fMRI. The resting‐state fluctuation amplitude (RSFA) in the fMRI signal (rsfMRI) has been proposed as an index of vascular reactivity. The RSFA compares favourably with other techniques such as breath‐hold and hypercapnia, but the latter are more difficult to perform in some populations, such as older adults. The RSFA is therefore a candidate for use in adjusting for age‐related changes in vascular reactivity in fMRI studies. The use of RSFA is predicated on its sensitivity to vascular rather than neural factors; however, the extent to which each of these factors contributes to RSFA remains to be characterized. The present work addressed these issues by comparing RSFA (i.e., rsfMRI variability) to proxy measures of (i) cardiovascular function in terms of heart rate (HR) and heart rate variability (HRV) and (ii) neural activity in terms of resting state magnetoencephalography (rsMEG). We derived summary scores of RSFA, a sensorimotor task BOLD activation, cardiovascular function and rsMEG variability for 335 healthy older adults in the population‐based Cambridge Centre for Ageing and Neuroscience cohort (Cam‐CAN; www.cam-can.com). Mediation analysis revealed that the effects of ageing on RSFA were significantly mediated by vascular factors, but importantly not by the variability in neuronal activity. Furthermore, the converse effects of ageing on the rsMEG variability were not mediated by vascular factors. We then examined the effect of RSFA scaling of task‐based BOLD in the sensorimotor task. The scaling analysis revealed that much of the effects of age on task‐based activation studies with fMRI do not survive correction for changes in vascular reactivity, and are likely to have been overestimated in previous fMRI studies of ageing. The results from the mediation analysis demonstrate that RSFA is modulated by measures of vascular function and is not driven solely by changes in the variance of neural activity. Based on these findings we propose that the RSFA scaling method is articularly useful in large scale and longitudinal neuroimaging studies of ageing, or with frail participants, where alternative measures of vascular reactivity are impractical. Hum Brain Mapp 36:2248–2269, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:25727740

Confounding Problems in Multifactor AOV When Using Several Organismic Variables of Limited Reliability

ERIC Educational Resources Information Center

Games, Paul A.

1975-01-01

A brief introduction is presented on how multiple regression and linear model techniques can handle data analysis situations that most educators and psychologists think of as appropriate for analysis of variance. (Author/BJG)

Beyond total treatment effects in randomised controlled trials: Baseline measurement of intermediate outcomes needed to reduce confounding in mediation investigations.

PubMed

Landau, Sabine; Emsley, Richard; Dunn, Graham

2018-06-01

Random allocation avoids confounding bias when estimating the average treatment effect. For continuous outcomes measured at post-treatment as well as prior to randomisation (baseline), analyses based on (A) post-treatment outcome alone, (B) change scores over the treatment phase or (C) conditioning on baseline values (analysis of covariance) provide unbiased estimators of the average treatment effect. The decision to include baseline values of the clinical outcome in the analysis is based on precision arguments, with analysis of covariance known to be most precise. Investigators increasingly carry out explanatory analyses to decompose total treatment effects into components that are mediated by an intermediate continuous outcome and a non-mediated part. Traditional mediation analysis might be performed based on (A) post-treatment values of the intermediate and clinical outcomes alone, (B) respective change scores or (C) conditioning on baseline measures of both intermediate and clinical outcomes. Using causal diagrams and Monte Carlo simulation, we investigated the performance of the three competing mediation approaches. We considered a data generating model that included three possible confounding processes involving baseline variables: The first two processes modelled baseline measures of the clinical variable or the intermediate variable as common causes of post-treatment measures of these two variables. The third process allowed the two baseline variables themselves to be correlated due to past common causes. We compared the analysis models implied by the competing mediation approaches with this data generating model to hypothesise likely biases in estimators, and tested these in a simulation study. We applied the methods to a randomised trial of pragmatic rehabilitation in patients with chronic fatigue syndrome, which examined the role of limiting activities as a mediator. Estimates of causal mediation effects derived by approach (A) will be biased if one of the three processes involving baseline measures of intermediate or clinical outcomes is operating. Necessary assumptions for the change score approach (B) to provide unbiased estimates under either process include the independence of baseline measures and change scores of the intermediate variable. Finally, estimates provided by the analysis of covariance approach (C) were found to be unbiased under all the three processes considered here. When applied to the example, there was evidence of mediation under all methods but the estimate of the indirect effect depended on the approach used with the proportion mediated varying from 57% to 86%. Trialists planning mediation analyses should measure baseline values of putative mediators as well as of continuous clinical outcomes. An analysis of covariance approach is recommended to avoid potential biases due to confounding processes involving baseline measures of intermediate or clinical outcomes, and not simply for increased precision.

Hippocampal sclerosis of aging, a prevalent and high-morbidity brain disease

PubMed Central

Smith, Charles D.; Abner, Erin L.; Wilfred, Bernard J.; Wang, Wang-Xia; Neltner, Janna H.; Baker, Michael; Fardo, David W.; Kryscio, Richard J.; Scheff, Stephen W.; Jicha, Gregory A.; Jellinger, Kurt A.; Van Eldik, Linda J.; Schmitt, Frederick A.

2013-01-01

Hippocampal sclerosis of aging (HS-Aging) is a causative factor in a large proportion of elderly dementia cases. The current definition of HS-Aging rests on pathologic criteria: neuronal loss and gliosis in the hippocampal formation that is out of proportion to AD-type pathology. HS-Aging is also strongly associated with TDP-43 pathology. HS-Aging pathology appears to be most prevalent in the oldest-old: autopsy series indicate that 5–30 % of nonagenarians have HS-Aging pathology. Among prior studies, differences in study design have contributed to the study-to-study variability in reported disease prevalence. The presence of HS-Aging pathology correlates with significant cognitive impairment which is often misdiagnosed as AD clinically. The antemortem diagnosis is further confounded by other diseases linked to hippocampal atrophy including frontotemporal lobar degeneration and cerebrovascular pathologies. Recent advances characterizing the neurocognitive profile of HS-Aging patients have begun to provide clues that may help identify living individuals with HS-Aging pathology. Structural brain imaging studies of research subjects followed to autopsy reveal hippocampal atrophy that is substantially greater in people with eventual HS-Aging pathology, compared to those with AD pathology alone. Data are presented from individuals who were followed with neurocognitive and neuroradiologic measurements, followed by neuropathologic evaluation at the University of Kentucky. Finally, we discuss factors that are hypothesized to cause or modify the disease. We conclude that the published literature on HS-Aging provides strong evidence of an important and under-appreciated brain disease of aging. Unfortunately, there is no therapy or preventive strategy currently available. PMID:23864344

Proximity of residence to an old mineral storage site in Chile and blood lead levels in children.

PubMed

Lisboa, Loreto; Klarián, José; Campos, Rosario Toro; Iglesias, Verónica

2016-01-01

Evidence suggests that an old mineral storage site removed in 1998 due to high lead content, remains as a source of exposure in the city of Antofagasta, Chile. The aim was to determine the association between blood lead levels in children and the residential proximity to the old mineral storage site. A cross sectional study was conducted with 185 children aged 7 to 16 years. The outcome variable was blood lead levels measured in 2005. The exposure variable was the distance between the current residence and the old mineral storage site. The distance was measured in meters by Geographic Information System (GIS). The median blood lead level in 2005 was 3.3μg/dL (interquartile range ‒ IQR: 2.0-4.3). A significant inverse association was found between the residential distance to the old mineral storage site and the blood lead levels in children, after adjusting by confounders (β: -0.04; 95%CI: -0.09; -0.01). This result suggests that the old mineral storage site continues to be a source of lead exposure for the children living nearby.

[Referral to internal medicine for alcoholism: influence on follow-up care].

PubMed

Avila, P; Marcos, M; Avila, J J; Laso, F J

2008-11-01

The problem of high rates of patient drop-out in alcohol treatment programs is frequently reported in the literature. Our aim was to investigate if internal medicine referral could improve abstinence and retention rates in a cohort of alcoholic patients. A retrospective observational study was conducted comparing 200 alcoholic patients attending a psychiatric unit (group 1) with 100 patients attending both this unit and an internal medicine unit (group 2). We collected sociodemographic and clinical variables and analysed differences regarding abstinence and retention rates by means of univariate and multivariate analysis. At 3 and 12 months follow-up, group 2 patients had higher retention and abstinence rates than group 1 patients. Multivariate analysis including potential confounding variables showed that independent predictors of one-year retention were internal medicine referral and being married. Independent predictors of one-year abstinence were being married, age > 44 years and receipt of drug treatment. The higher retention rate found among patients referred to Internal Medicine specialists, a result that has not been previously reported to the best of our knowledge, emphasizes the importance of a multidisciplinary team approach in the treatment of alcoholism.

Parafunctional habits are associated cumulatively to painful temporomandibular disorders in adolescents.

PubMed

Fernandes, Giovana; Franco-Micheloni, Ana Lúcia; Siqueira, José Tadeu Tesseroli; Gonçalves, Daniela Aparecida Godói; Camparis, Cinara Maria

2016-01-01

This cross-sectional study was designed to evaluate the effect of sleep bruxism, awake bruxism and parafunctional habits, both separately and cumulatively, on the likelihood of adolescents to present painful TMD. The study was conducted on a sample of 1,094 adolescents (aged 12-14). The presence of painful TMD was assessed using the Research Diagnostic Criteria for Temporomandibular Disorders, Axis I. Data on sleep bruxism, awake bruxism and parafunctional habits (nail/pen/pencil/lip/cheek biting, resting one's head on one's hand, and gum chewing) were researched by self-report. After adjusting for potential demographic confounders using logistic regression, each of the predictor variables (sleep bruxism, awake bruxism and parafunctional habits) was significantly associated with painful TMD. In addition, the odds for painful TMD were higher in the concomitant presence of two (OR=4.6, [95%CI=2.06, 10.37]) or three predictor (OR=13.7, [95%CI=5.72, 32.96]) variables. These findings indicate that the presence of concomitant muscle activities during sleep and awake bruxism and parafunctional habits increases the likelihood almost linearly of adolescents to present painful TMD.

The Typicality Ranking Task: A New Method to Derive Typicality Judgments from Children.

PubMed

Djalal, Farah Mutiasari; Ameel, Eef; Storms, Gert

2016-01-01

An alternative method for deriving typicality judgments, applicable in young children that are not familiar with numerical values yet, is introduced, allowing researchers to study gradedness at younger ages in concept development. Contrary to the long tradition of using rating-based procedures to derive typicality judgments, we propose a method that is based on typicality ranking rather than rating, in which items are gradually sorted according to their typicality, and that requires a minimum of linguistic knowledge. The validity of the method is investigated and the method is compared to the traditional typicality rating measurement in a large empirical study with eight different semantic concepts. The results show that the typicality ranking task can be used to assess children's category knowledge and to evaluate how this knowledge evolves over time. Contrary to earlier held assumptions in studies on typicality in young children, our results also show that preference is not so much a confounding variable to be avoided, but that both variables are often significantly correlated in older children and even in adults.

The Typicality Ranking Task: A New Method to Derive Typicality Judgments from Children

PubMed Central

Ameel, Eef; Storms, Gert

2016-01-01

An alternative method for deriving typicality judgments, applicable in young children that are not familiar with numerical values yet, is introduced, allowing researchers to study gradedness at younger ages in concept development. Contrary to the long tradition of using rating-based procedures to derive typicality judgments, we propose a method that is based on typicality ranking rather than rating, in which items are gradually sorted according to their typicality, and that requires a minimum of linguistic knowledge. The validity of the method is investigated and the method is compared to the traditional typicality rating measurement in a large empirical study with eight different semantic concepts. The results show that the typicality ranking task can be used to assess children’s category knowledge and to evaluate how this knowledge evolves over time. Contrary to earlier held assumptions in studies on typicality in young children, our results also show that preference is not so much a confounding variable to be avoided, but that both variables are often significantly correlated in older children and even in adults. PMID:27322371

Association between the triglyceride to high-density lipoprotein cholesterol ratio and insulin resistance in Korean adolescents: a nationwide population-based study.

PubMed

Park, Jae-Min; Lee, Jee-Yon; Dong, Jae June; Lee, Duk-Chul; Lee, Yong-Jae

2016-11-01

Studies have suggested the triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) as a surrogate marker of insulin resistance. However, few studies have examined the association between TG/HDL-C and insulin resistance in the general adolescent population. This study aimed to examine the association between TG/HDL-C and insulin resistance in a nationally representative sample of Korean adolescents. A total of 2649 participants aged 12-18 years were selected from the 2007 to 2010 Korean National Health and Nutrition Examination Survey (KNHANES). Insulin resistance was defined as the homeostatic model assessment of insulin resistance (HOMA-IR) values greater than the 80th percentile. The mean values of most cardiometabolic variables increased proportionally with TG/HDL-C quartiles. Compared to individuals in the lowest TG/HDL-C quartile, the odds ratio for insulin resistance for individuals in the highest quartile was 2.91 in boys and 2.38 in girls after adjusting for confounding variables. This study suggests that TG/HDL-C could be a convenient marker for identifying Korean adolescents with insulin resistance.

Adverse childhood or adult experiences and risk of bilateral oophorectomy: a population-based case–control study

PubMed Central

Gazzuola Rocca, Liliana; Smith, Carin Y; Grossardt, Brandon R; Faubion, Stephanie S; Shuster, Lynne T; Stewart, Elizabeth A

2017-01-01

Objectives Bilateral oophorectomy has commonly been performed in conjunction with hysterectomy even in women without a clear ovarian indication; however, oophorectomy may have long-term deleterious consequences. To better understand this surgical practice from the woman’s perspective, we studied the possible association of adverse childhood or adult experiences with the subsequent occurrence of bilateral oophorectomy. Design Population-based case–control study. Setting Olmsted County, Minnesota (USA). Participants From an established population-based cohort study, we sampled 128 women who underwent bilateral oophorectomy before age 46 years for a non-cancerous condition in 1988–2007 (cases) and 128 age-matched controls (±1 year). Methods Information about adverse experiences was abstracted from the medical records dating back to age 15 years or earlier archived in the Rochester Epidemiology Project (REP) records-linkage system. Adverse childhood experiences were summarised using the Adverse Childhood Experience (ACE) score. Results We observed an association of bilateral oophorectomy performed before age 46 years with verbal or emotional abuse, physical abuse, any abuse, substance abuse in the household, and with an ACE score ≥1 experienced before age 19 years (OR=3.23; 95% CI 1.73 to 6.02; p<0.001). In women who underwent the oophorectomy before age 40 years, we also observed a strong association with physical abuse experienced during adulthood (OR=4.33; 95% CI 1.23 to 15.21; p=0.02). Several of the associations were higher in women who underwent oophorectomy at a younger age (<40 years) and in women without an ovarian indication for the surgery. None of the psychosocial or medical variables explored as potential confounders or intervening variables changed the results noticeably. Conclusions Women who suffered adverse childhood experiences or adult abuse are at increased risk of undergoing bilateral oophorectomy before menopause. We suggest that the association may be explained by a series of biological, emotional, and psychodynamic mechanisms. PMID:28592582

The protracted waste crisis and physical health of workers in Beirut: a comparative cross-sectional study.

PubMed

Morsi, Rami Z; Safa, Rawan; Baroud, Serge F; Fawaz, Cherine N; Farha, Jad I; El-Jardali, Fadi; Chaaya, Monique

2017-04-11

Since July 2015, Lebanon has been experiencing a waste management crisis. Dumpsites in inhabited areas and waste burning have emerged due to the waste accumulation, further adding to the gravity of the situation. However, the association between the crisis and health of the population has not been scientifically reported. A comparative cross-sectional study was conducted to assess whether exposure to open dumpsites and waste burning is associated with acute health symptoms. The study sample included 221 male workers between the ages of 18-60 years selected from two areas chosen based on their proximity to a garbage dumpsite and waste burning. 110 workers were exposed to a garbage dumpsite and waste burning, and 111 workers were not. Data were collected via a face-to-face interview using a newly developed validated structured questionnaire. Chi-square tests were used to check for statistically significant differences between exposure and covariates. Multivariable analyses using multiple logistic regression were used to compare health symptoms between exposed and unexposed workers adjusting for potential confounders. The prevalence of acute health symptoms was greater among the exposed workers than the non-exposed workers, including gastrointestinal, respiratory, dermatological and constitutional symptoms. Controlling for confounding variables, such as age, insurance, family support, residence near dumpsite, work site, and smoking, a minimum odds ratio (OR) of 4.30 was obtained when comparing the exposed population to those non-exposed. The strong association between improper waste management and physical health calls for immediate attention by the government, stakeholders and community members to find optimal solutions for this waste management crisis and set immediate priority interventions such as regular waste collection, volume reduction and recycling performance improvement. However, the long recall period may have underestimated our results.

The physiological determinants of low-level urine cadmium: an assessment in a cross-sectional study among schoolchildren.

PubMed

Wang, Hongyu; Dumont, Xavier; Haufroid, Vincent; Bernard, Alfred

2017-09-12

Recent studies in children have reported associations of urinary cadmium (U-Cd), used as biomarker of Cd body burden, with renal dysfunction, retarded growth and impaired cognitive development in children. Little is known, however, about factors influencing U-Cd in children and likely to act as confounders. In a cross-sectional study involving 249 schoolchildren (mean age, 5.72 years; 138 boys), we measured the urine concentrations of cadmium, zinc, lead, albumin, alpha 1 -microglobulin (A1M), retinol-binding protein, β 2 -microglobulin and club cell protein (CC16). Determinants of U-Cd expressed per creatinine or adjusted to specific gravity were identified by multiple regression analyses. Girls and boys had similar median concentrations of U-Cd (0.22 and 0.24 μg/L, 0.33 and 0.35 μg/g creatinine, respectively). When models were run without including creatinine or specific gravity among independent variables, urinary zinc, urinary A1M and age emerged as the strongest predictors of U-Cd expressed per g creatinine or adjusted to SG. When adding creatinine among predictors, urinary creatinine emerged as an additional strong predictor correlating negatively with U-Cd per g creatinine. This strong residual influence of diuresis, not seen when adding specific gravity among predictors, linked U-Cd to U-A1M or U-CC16 through secondary associations mimicking those induced by Cd nephrotoxity. In young children U-Cd largely varies with diuresis, zinc metabolism and urinary A1M. These physiological determinants, unrelated to Cd body burden, may confound the child renal and developmental outcomes associated with low-level U-Cd.

The possible societal impact of the decrease in U.S. blood lead levels on adult IQ.

PubMed

Kaufman, Alan S; Zhou, Xiaobin; Reynolds, Matthew R; Kaufman, Nadeen L; Green, Garo P; Weiss, Lawrence G

2014-07-01

The dramatic decrease in U.S. blood lead levels (BLLs) since the 1970s has been documented--however, the anticipated societal impact on intelligence quotient (IQ) has not. The objectives of this study were to determine whether mean IQs of American adults, adjusted for demographics, have increased in concert with society's decreasing BLL. Mean IQs of eight normal adult cohorts (N=800), tested individually in 2007 by trained clinicians, were compared using ANCOVA and correlation analysis. Cohorts ranged in mean societal BLLs from 4 1/2 μg/dL (born 1985-1987) to 19 μg/dL (born 1963-1972). IQs were adjusted for confounders-education, gender, ethnicity, region, urban status. To control for age, we analyzed IQ data for a second adult sample (N=800), tested in 1995-all born when BLLs were high (1951-1975, BLL ≥ 15 μg/dL). When controlling for education, gender, ethnicity, and region, the regression of IQs on BLLs was significant (r=-0.84, p<0.01); the modeled change in BLLs from 20 to 4 μg/dL suggests predicted increases of 3.8 IQ points (95% CI, 1.4-6.2). Also controlling for urban status produced significance (r=-0.88, p<0.01) with predicted increases of 5.2 points (95% CI, 2.4-8.0). Control analyses ruled out aging as a confounder. The dramatic societal decreases in BLLs in the U.S. since the 1970s were associated with a 4-5-point increase in the mean IQs of Americans. This effect is consistent with researchers' predictions; however, other variables (e.g., medical advances) may have contributed to the IQ gains. Copyright © 2014 Elsevier Inc. All rights reserved.

Effectiveness in prevention of travellers' diarrhoea by an oral cholera vaccine WC/rBS.

PubMed

López-Gigosos, R; García-Fortea, P; Reina-Doña, E; Plaza-Martín, E

2007-11-01

To investigate the effectiveness of an oral cholera vaccine (Dukoral((R))) in preventing travellers' diarrhoea. A retrospective study was conducted among travellers who had attended the International Vaccination Centre in Malaga, Spain, before starting their journey. A telephone interview was undertaken from November 2005 to January 2006 after the travellers had returned from their trip. The relationship between vaccination with Dukoral((R)) and travellers' diarrhoea was analysed by means of a logistic regression model, adjusting for possible confounding variables (traveller's age, duration of trip and region visited). The overall incidence of diarrhoea in vaccinated travellers was 23% compared with 40% in non-vaccinated travellers (historical control group) (p=0.004). Short episodes of diarrhoea were reported in significantly more travellers of the vaccinated group than of the non-vaccinated group (average duration of diarrhoea 2.21 days versus 3.97 days, p=0.005). The incidence of diarrhoea was significantly lower among vaccinated than non-vaccinated travellers who went to Africa for less than 3 weeks (16% versus 48%, p=0.002) or India and South East Asia (19% versus 50%, p =0.052) for more than 3 weeks. No adverse events were reported in the group of vaccinated travellers. Vaccination reduced the risk of travellers' diarrhoea by 43%; possibly due to the protective effect of the oral vaccine Dukoral((R)) against travellers' diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) or cholera. The efficacy of vaccination increased after adjusting for confounding factors, being modified by traveller age (under 30 years, or 45 years and older the protective effect of the vaccine is 4.8 greater, 95% confidence interval (CI): 2.1-10.7). The number needed to treat to prevent one traveller from suffering from one or more episodes of travellers' diarrhoea was 5.8.

Violent behavior and aggression in schizophrenia: Prevalence and risk factors. A multicentric study from three Latin-America countries.

PubMed

Caqueo-Urízar, Alejandra; Fond, Guillaume; Urzúa, Alfonso; Boyer, Laurent; Williams, David R

2016-12-01

The aim of the present study was (i) to assess the prevalence of Violent Behavior in Schizophrenia (VBS) in a sample of community-dwelling outpatients in three middle-income countries of Latin America and (ii) to determine the clinical and socio-demographical risk factors associated with VBS and aggression level. The study included 253 stabilized outpatients with schizophrenia and their principal caregivers from 3 public ambulatory psychiatric care centers in Bolivia (N=83), Chile (N=85), and Peru (N=85). VBS was defined according to the Overt Aggression Scale (OAS) score and the aggression level was measured by the aggression subscore of the Agitated Behavior Scale of Corrigan. We collected socio-demographic information and clinical data. Multiple linear and logistic regressions were performed to determine which variables were associated with VBS and aggression level. The prevalence of VBS differed statistically between the three countries (p<0.001) with 3.5% in Chile, 14.6% in Peru and 55.4% in Bolivia. After adjustment for confounding factors, VBS was associated with a younger age, a more severe psychotic symptomatology, a lower family income and unemployment. After adjustment for confounding factors, aggression level was associated with a more severe psychotic symptomatology, a lower family income, a younger age at illness onset and higher number of hospitalizations in the last 3years. These results may guide future health policies to specifically provide social support and rehabilitation care to VBS patients in middle-income countries, including psychoeducation and a more integrated work between the treating medical team and the social workers. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-reported body silhouette trajectories across the lifespan and excessive daytime sleepiness in adulthood: a retrospective analysis. The Paris Prospective Study III

PubMed Central

Tafflet, Muriel; Charles, Marie-Aline; Thomas, Frédérique; Boutouyrie, Pierre; Guibout, Catherine; Haba-Rubio, José; Périer, Marie Cécile; Pannier, Bruno; Marques-Vidal, Pedro; Jouven, Xavier; Empana, Jean-Philippe

2018-01-01

Objectives Excessive daytime sleepiness (EDS) is a common sleep complaint in the population and is increasingly recognised as deleterious for health. Simple and sensitive tools allowing identifying individuals at greater risk of EDS would be of public health importance. Hence, we determined trajectories of body silhouette from early childhood to adulthood and evaluated their association with EDS in adulthood. Design A retrospective analysis in a prospective community-based study. Participants 6820 men and women self-reported their silhouette at ages 8, 15, 25, 35 and 45 using the body silhouettes proposed by Stunkard et al. EDS was defined by an Epworth Sleepiness Scale score ≥11. Main outcome measure Presence of EDS in adulthood. Results The study population comprised 6820 participants (mean age 59.8 years, 61.1% men). Five distinct body silhouettes trajectories over the lifespan were identified: 31.9% ‘lean stable’, 11.1% ‘lean increase’, 16.1% ‘lean-marked increase’, 32.5% ‘moderate stable’ and 8.4% ‘heavy stable’. Subjects with a ‘heavy-stable’ trajectory (OR 1.24, 95% CI 0.94 to 1.62) and those with a ‘lean-marked increase’ trajectory (OR 1.46, 95% CI 1.18 to 1.81) were more likely to have EDS when compared with the ‘lean-stable’ group after adjusting for confounding. Further adjustment for birth weight strengthened the magnitude of the ORs. Conclusion Increasing body silhouette and to a lesser extent constantly high body silhouette trajectory from childhood to adulthood are associated with increased likelihood of EDS, independently of major confounding variables. Trial registration number NCT00741728; Pre-results. PMID:29593025

The Relationship between Intake of Dairy Products and Polycystic Ovary Syndrome in Women Who Referred to Isfahan University of Medical Science Clinics in 2013

PubMed Central

Rajaeieh, Golnaz; Marasi, Mohamadreza; Shahshahan, Zahra; Hassanbeigi, Fatemmeh; Safavi, Seied Morteza

2014-01-01

Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive women. Nearly 10% of young women in this period involved. Although factors such as Insulin Resistance, hyper insulinemia, obesity and dietary are suggested to be associated with PCOS, cause of PCOS is not completely understood. Dairy products (a key component of the usual diet) of participants can also affect the factors of this disease and may have beneficial effects on treatment of PCOS. However, research in this area is scarce. The purpose of this study was to evaluate the relationship between dairy products consumption and PCOS. Methods: This descriptive cross-sectional study of 400 women was conducted in Shahid Beheshti Hospital of Isfahan University of Medical Science, Iran. Dietary intake was evaluated by validated food frequency questionnaire. Other variables such as ovarian disease, inherited predisposition, age at menarche, physical activity and history of other diseases were evaluated using questionnaire. Data analysis was performed by a logistic regression test using SPSS software version 15 Predictive analytics software and solutions. Results: There were a significant association between PCOS and ovarian disease (P < 0.001), age (P < 0.001) and using medication (P = 0.001). Body mass index (BMI) was inversely associated with PCOS, but it was not significant (P = 0.068). There was a significant direct relationship between milk consumption and risk of PCOS after adjusting for confounding factors (P = 0.028). Conclusions: The findings of this study indicated that ovarian disease and medication use is directly linked to PCOS. Dairy consumption was not significantly correlated with PCOS. However, after adjustment for confounders, there was an direct relationship between milk consumption and risk of PCOS. PMID:25013687

Can we predict urinary stress incontinence by using demographic, clinical, imaging and urodynamic data?

PubMed

Wlaźlak, Edyta; Surkont, Grzegorz; Shek, Ka L; Dietz, Hans P

2015-10-01

It has been claimed that urethral hypermobility and resting urethral pressure can largely explain stress incontinence in women. In this study we tried to replicate these findings in an unselected cohort of women seen for urodynamic testing, including as many potential confounders as possible. This study is a retrospective analysis of data obtained from 341 women. They attended for urodynamic testing due to symptoms of pelvic floor dysfunction. We excluded from the analysis women with a history of previous anti-incontinence and prolapse surgery. All patients had a standardised clinical assessment, 4D transperineal pelvic floor ultrasound and multichannel urodynamic testing. Urodynamic stress incontinence (USI) was diagnosed by multichannel urodynamic testing. Its severity was subjectively graded as mild, moderate and severe. Candidate variables were: age, BMI, symptoms of prolapse, vaginal parity, significant prolapse (compartment-specific), levator avulsion, levator hiatal area, Oxford grading, midurethral mobility, maximum urethral pressure (MUP), maximum cough pressure and maximum Valsalva pressure reached. On binary logistic regression, the following parameters were statistically significant in predicting urodynamic stress incontinence: age (P=0.03), significant rectocele (P=0.02), max. abdominal pressure reached (negatively, P<0.0001), midurethral mobility (P=0.0004) and MUP (negatively, P<0.0001). On multivariate analysis, accounting for multiple interdependencies, the following predictors remained significant: max. abdominal pressure reached (negatively, P<0.0001), cough pressure (P=0.006), midurethral mobility (P=0.003) and MUP (negatively, P<0.0001), giving an R(2) of 0.24. Mid-urethral mobility and MUP are the main predictors of USI. Demographic and clinical data are at best weak predictors. Our results suggest the presence of major unrecognised confounders. Copyright © 2015. Published by Elsevier Ireland Ltd.

The Relationship between Intake of Dairy Products and Polycystic Ovary Syndrome in Women Who Referred to Isfahan University of Medical Science Clinics in 2013.

PubMed

Rajaeieh, Golnaz; Marasi, Mohamadreza; Shahshahan, Zahra; Hassanbeigi, Fatemmeh; Safavi, Seied Morteza

2014-06-01

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive women. Nearly 10% of young women in this period involved. Although factors such as Insulin Resistance, hyper insulinemia, obesity and dietary are suggested to be associated with PCOS, cause of PCOS is not completely understood. Dairy products (a key component of the usual diet) of participants can also affect the factors of this disease and may have beneficial effects on treatment of PCOS. However, research in this area is scarce. The purpose of this study was to evaluate the relationship between dairy products consumption and PCOS. This descriptive cross-sectional study of 400 women was conducted in Shahid Beheshti Hospital of Isfahan University of Medical Science, Iran. Dietary intake was evaluated by validated food frequency questionnaire. Other variables such as ovarian disease, inherited predisposition, age at menarche, physical activity and history of other diseases were evaluated using questionnaire. Data analysis was performed by a logistic regression test using SPSS software version 15 Predictive analytics software and solutions. There were a significant association between PCOS and ovarian disease (P < 0.001), age (P < 0.001) and using medication (P = 0.001). Body mass index (BMI) was inversely associated with PCOS, but it was not significant (P = 0.068). There was a significant direct relationship between milk consumption and risk of PCOS after adjusting for confounding factors (P = 0.028). The findings of this study indicated that ovarian disease and medication use is directly linked to PCOS. Dairy consumption was not significantly correlated with PCOS. However, after adjustment for confounders, there was an direct relationship between milk consumption and risk of PCOS.

Impact of parity on anthropometric measures of obesity controlling by multiple confounders: a cross-sectional study in Chilean women.

PubMed

Koch, E; Bogado, M; Araya, F; Romero, T; Díaz, C; Manriquez, L; Paredes, M; Román, C; Taylor, A; Kirschbaum, A

2008-05-01

To find out whether there is an association between parity and obesity, evaluated through body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) in Chilean women after controlling for sociodemographic characteristics, health risk and gynaeco-obstetric factors. Cross-sectional study, using baseline data of the San Francisco Project. San Francisco de Mostazal, located in the central region of Chile, 6512 Chilean-Hispanic women (Spanish heritage with a variable indigenous component). A weighted random sample of 508 women who had their first pregnancy inside the primary child-bearing ages. Data were collected between 1997 and 1999. Statistical associations between parity and different anthropometric measurements of adiposity in multiple linear (MLnR) and logistic regression models (MLtR) were evaluated. In MLnR a modest parity-related increment in BMI and practically null increment in WC, WHR and WHtR was observed. Covariates that showed a statistically significant association with anthropometric measures of adiposity were age, low education, marital status, employment, smoking, smoking cessation, hypertension, diabetes, dyslipidaemia, parent's obesity, menarche and fetal macrosomia. Crude odds ratio (OR) showed a strong association between parity and anthropometric markers of obesity. Nevertheless, after adjustments in MLtR models, the association remained only for BMI. All the measures of abdominal obesity related to parous women showed OR smaller than 1 (95% confidence intervals 0.57 to 0.96). Parity modestly influences BMI, but does not seem to be related to WC, WHR and WHtR after controlling by confounders. Parity can increase adiposity but not necessarily following an abdominal pattern.

Impact of breastfeeding duration on age at menarche.

PubMed

Al-Sahab, Ban; Adair, Linda; Hamadeh, Mazen J; Ardern, Chris I; Tamim, Hala

2011-05-01

The study aims to assess the relation between breastfeeding duration and age at menarche. Analysis was based on a cohort of 994 Filipino girls born in 1983-1984 and followed up from infancy to adulthood by the Cebu Longitudinal Health and Nutrition Survey. The main outcome was self-reported age at menarche. Cox regression was used to investigate the relation between duration of exclusive and any breastfeeding with age at menarche with adjustment sequentially for specific sets of known socioeconomic, maternal, genetic, and prenatal confounders. The estimated median of age at menarche was 13.08 years. After adjustment for potential confounders of the association of breastfeeding with age at menarche, exclusive breastfeeding duration retained an independent and significant association with age at menarche. An increase in 1 month of exclusive breastfeeding decreases the hazard of attaining earlier menarche by 6% (hazard ratio = 0.94, 95% confidence interval: 0.90, 0.98). Any breastfeeding duration was not associated with age at menarche. Although this is the first longitudinal study that reveals a negative association between exclusive breastfeeding and early menarche, the relation is still elusive. Further longitudinal studies within different contexts are warranted to assess the generalizability of these findings.

Materialism across the life span: An age-period-cohort analysis.

PubMed

Jaspers, Esther D T; Pieters, Rik G M

2016-09-01

This research examined the development of materialism across the life span. Two initial studies revealed that (a) lay beliefs were that materialism declines with age and (b) previous research findings also implied a modest, negative relationship between age and materialism. Yet, previous research has considered age only as a linear control variable, thereby precluding the possibility of more intricate relationships between age and materialism. Moreover, prior studies have relied on cross-sectional data and thus confound age and cohort effects. To improve on this, the main study used longitudinal data from 8 waves spanning 9 years of over 4,200 individuals (16 to 90 years) to examine age effects on materialism while controlling for cohort and period effects. Using a multivariate multilevel latent growth model, it found that materialism followed a curvilinear trajectory across the life span, with the lowest levels at middle age and higher levels before and after that. Thus, in contrast to lay beliefs, materialism increased in older age. Moreover, age effects on materialism differed markedly between 3 core themes of materialism: acquisition centrality, possession-defined success, and acquisition as the pursuit of happiness. In particular, acquisition centrality and possession-defined success were higher at younger and older age. Independent of these age effects, older birth cohorts were oriented more toward possession-defined success, whereas younger birth cohorts were oriented more toward acquisition centrality. The economic downturn since 2008 led to a decrease in acquisition as the pursuit of happiness and in desires for personal growth, but to an increase in desires for achievement. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Vehicle year and the risk of car crash injury

PubMed Central

Blows, S; Ivers, R; Woodward, M; Connor, J; Ameratunga, S; Norton, R

2003-01-01

Objective: To quantify the association between vehicle age and risk of car crash injury. Design and setting: Data from a population based case-control study conducted in the Auckland region in 1998/99 was used to examine the adjusted risk of car crash injury or death due to vehicle age, after controlling for a range of known confounders. Cases were all cars involved in crashes in which at least one occupant was hospitalized or killed anywhere in the Auckland region, and controls were randomly selected cars on Auckland roads. The drivers of the 571 case vehicles and 588 control vehicles completed a structured interview. Main outcome measure: Hospitalisation or death of a vehicle occupant due to car crash injury. Results: Vehicles constructed before 1984 had significantly greater chance of being involved in an injury crash than those constructed after 1994 (odds ratio 2.88, 95% confidence interval (CI) 1.20 to 6.91), after adjustment for potential confounders. There was also a trend for increasing crash risk with each one year increase in vehicle age after adjustment for potential confounders (odds ratio 1.05, 95% CI 0.99 to 1.11; p = 0.09). Conclusion: This study quantifies the increased risk of car crash injury associated with older vehicle year and confirms this as an important public health issue. PMID:14693899

Vehicle year and the risk of car crash injury.

PubMed

Blows, S; Ivers, R Q; Woodward, M; Connor, J; Ameratunga, S; Norton, R

2003-12-01

To quantify the association between vehicle age and risk of car crash injury. Data from a population based case-control study conducted in the Auckland region in 1998/99 was used to examine the adjusted risk of car crash injury or death due to vehicle age, after controlling for a range of known confounders. Cases were all cars involved in crashes in which at least one occupant was hospitalized or killed anywhere in the Auckland region, and controls were randomly selected cars on Auckland roads. The drivers of the 571 case vehicles and 588 control vehicles completed a structured interview. Hospitalisation or death of a vehicle occupant due to car crash injury. Vehicles constructed before 1984 had significantly greater chance of being involved in an injury crash than those constructed after 1994 (odds ratio 2.88, 95% confidence interval (CI) 1.20 to 6.91), after adjustment for potential confounders. There was also a trend for increasing crash risk with each one year increase in vehicle age after adjustment for potential confounders (odds ratio 1.05, 95% CI 0.99 to 1.11; p = 0.09). This study quantifies the increased risk of car crash injury associated with older vehicle year and confirms this as an important public health issue.

Unconditional or Conditional Logistic Regression Model for Age-Matched Case-Control Data?

PubMed

Kuo, Chia-Ling; Duan, Yinghui; Grady, James

2018-01-01

Matching on demographic variables is commonly used in case-control studies to adjust for confounding at the design stage. There is a presumption that matched data need to be analyzed by matched methods. Conditional logistic regression has become a standard for matched case-control data to tackle the sparse data problem. The sparse data problem, however, may not be a concern for loose-matching data when the matching between cases and controls is not unique, and one case can be matched to other controls without substantially changing the association. Data matched on a few demographic variables are clearly loose-matching data, and we hypothesize that unconditional logistic regression is a proper method to perform. To address the hypothesis, we compare unconditional and conditional logistic regression models by precision in estimates and hypothesis testing using simulated matched case-control data. Our results support our hypothesis; however, the unconditional model is not as robust as the conditional model to the matching distortion that the matching process not only makes cases and controls similar for matching variables but also for the exposure status. When the study design involves other complex features or the computational burden is high, matching in loose-matching data can be ignored for negligible loss in testing and estimation if the distributions of matching variables are not extremely different between cases and controls.

Unconditional or Conditional Logistic Regression Model for Age-Matched Case–Control Data?

PubMed Central

Kuo, Chia-Ling; Duan, Yinghui; Grady, James

2018-01-01

Matching on demographic variables is commonly used in case–control studies to adjust for confounding at the design stage. There is a presumption that matched data need to be analyzed by matched methods. Conditional logistic regression has become a standard for matched case–control data to tackle the sparse data problem. The sparse data problem, however, may not be a concern for loose-matching data when the matching between cases and controls is not unique, and one case can be matched to other controls without substantially changing the association. Data matched on a few demographic variables are clearly loose-matching data, and we hypothesize that unconditional logistic regression is a proper method to perform. To address the hypothesis, we compare unconditional and conditional logistic regression models by precision in estimates and hypothesis testing using simulated matched case–control data. Our results support our hypothesis; however, the unconditional model is not as robust as the conditional model to the matching distortion that the matching process not only makes cases and controls similar for matching variables but also for the exposure status. When the study design involves other complex features or the computational burden is high, matching in loose-matching data can be ignored for negligible loss in testing and estimation if the distributions of matching variables are not extremely different between cases and controls. PMID:29552553

Neonatal pain-related stress, functional cortical activity and visual-perceptual abilities in school-age children born at extremely low gestational age.

PubMed

Doesburg, Sam M; Chau, Cecil M; Cheung, Teresa P L; Moiseev, Alexander; Ribary, Urs; Herdman, Anthony T; Miller, Steven P; Cepeda, Ivan L; Synnes, Anne; Grunau, Ruth E

2013-10-01

Children born very prematurely (< or =32 weeks) often exhibit visual-perceptual difficulties at school-age, even in the absence of major neurological impairment. The alterations in functional brain activity that give rise to such problems, as well as the relationship between adverse neonatal experience and neurodevelopment, remain poorly understood. Repeated procedural pain-related stress during neonatal intensive care has been proposed to contribute to altered neurocognitive development in these children. Due to critical periods in the development of thalamocortical systems, the immature brain of infants born at extremely low gestational age (ELGA; < or =28 weeks) may have heightened vulnerability to neonatal pain. In a cohort of school-age children followed since birth we assessed relations between functional brain activity measured using magnetoencephalogragy (MEG), visual-perceptual abilities and cumulative neonatal pain. We demonstrated alterations in the spectral structure of spontaneous cortical oscillatory activity in ELGA children at school-age. Cumulative neonatal pain-related stress was associated with changes in background cortical rhythmicity in these children, and these alterations in spontaneous brain oscillations were negatively correlated with visual-perceptual abilities at school-age, and were not driven by potentially confounding neonatal variables. These findings provide the first evidence linking neonatal pain-related stress, the development of functional brain activity, and school-age cognitive outcome in these vulnerable children. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Analysis of the machinery and intermediates of the 5hmC-mediated DNA demethylation pathway in aging on samples from the MARK-AGE Study.

PubMed

Valentini, Elisabetta; Zampieri, Michele; Malavolta, Marco; Bacalini, Maria Giulia; Calabrese, Roberta; Guastafierro, Tiziana; Reale, Anna; Franceschi, Claudio; Hervonen, Antti; Koller, Bernhard; Bernhardt, Jürgen; Slagboom, P Eline; Toussaint, Olivier; Sikora, Ewa; Gonos, Efstathios S; Breusing, Nicolle; Grune, Tilman; Jansen, Eugène; Dollé, Martijn E T; Moreno-Villanueva, María; Sindlinger, Thilo; Bürkle, Alexander; Ciccarone, Fabio; Caiafa, Paola

2016-08-29

Gradual changes in the DNA methylation landscape occur throughout aging virtually in all human tissues. A widespread reduction of 5-methylcytosine (5mC), associated with highly reproducible site-specific hypermethylation, characterizes the genome in aging. Therefore, an equilibrium seems to exist between general and directional deregulating events concerning DNA methylation controllers, which may underpin the age-related epigenetic changes. In this context, 5mC-hydroxylases (TET enzymes) are new potential players. In fact, TETs catalyze the stepwise oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), driving the DNA demethylation process based on thymine DNA glycosylase (TDG)-mediated DNA repair pathway. The present paper reports the expression of DNA hydroxymethylation components, the levels of 5hmC and of its derivatives in peripheral blood mononuclear cells of age-stratified donors recruited in several European countries in the context of the EU Project 'MARK-AGE'. The results provide evidence for an age-related decline of TET1 , TET3 and TDG gene expression along with a decrease of 5hmC and an accumulation of 5caC. These associations were independent of confounding variables, including recruitment center, gender and leukocyte composition. The observed impairment of 5hmC-mediated DNA demethylation pathway in blood cells may lead to aberrant transcriptional programs in the elderly.

Shift work and age as interactive predictors of body mass index among offshore workers.

PubMed

Parkes, Katharine R

2002-02-01

This study investigated shift pattern (day shifts versus day-night rotation) and its interactions with age, and with years of shiftwork exposure, as predictors of body mass index (BMI). Survey data were collected from offshore personnel working day shifts (N=787) or day-night shifts (N=787); information was obtained about shift pattern and years of shiftwork exposure, height, weight, demographic factors, and smoking habits. Hierarchical multiple regression was used to test a model in which BMI was predicted by additive and interactive effects of shift pattern, age, and exposure years with control for confounding variables. In a multivariate analysis (controlling for job type, education and smoking), BMI was predicted by the main effects of age and years of shiftwork exposure. Shift pattern was not significant as a main effect, but it interacted significantly with the curvilinear age term and with the linear and curvilinear components of shiftwork exposure. In the day shift group, age but not exposure predicted BMI; the opposite was true of the day-night shift group. The increase in BMI with an increase in age and exposure years was steeper for the day-night shift group than for the day shift group. The significant interaction effects found in this study were consistent with the view that continued exposure to day-night shift work gives rise to increases in BMI, over and above the normative effects of ageing on BMI shown by day-shift workers.

Social capital, the miniaturization of community and cannabis smoking among young adults.

PubMed

Lindström, Martin

2004-06-01

The impact of social participation, trust and the miniaturization of community, i.e. the combination of high social participation and low trust, on cannabis smoking was investigated. The 2000 public health survey in Scania is a cross-sectional study. A total of 13,715 persons aged 18-80 years, of which 3,978 persons aged 18-34 years were included in this study, answered a postal questionnaire, which represents 59% of the random sample. A logistic regression model was used to investigate the association between the social capital variables and ever having experienced cannabis smoking. The multivariate analysis was performed to investigate the importance of possible confounders (age, country of origin and education) on the differences in having experienced cannabis smoking according to social participation, trust and their four combination categories. Cannabis smoking is not associated with social participation, but positively associated with low trust among both men and women, and the miniaturization of community, i.e. the combination of high social participation and low trust, among men. This study suggests that the miniaturization of community, i.e. the combination of high social participation and low levels of generalized trust of other people, may enhance the experience of cannabis smoking.

A longitudinal analysis of shooter games and their relationship with conduct disorder and cself-reported delinquency.

PubMed

Smith, Sven; Ferguson, Chris; Beaver, Kevin

Despite several decades of research, little scholarly consensus has emerged regarding the role of violent video games in the development of youth psychopathology or crime. The current study employed the Avon Longitudinal Study of Parents and Children longitudinal dataset to examine the impact of the shooter game genre ownership in childhood on later adolescent conduct disorder and criminal behavior. Multivariate Poisson regressions with the robust estimator correlation matrix were performed comparing effects of independent and confounding variables. Results revealed that early childhood mental health symptoms at age seven related to ADHD, depression and early conduct disorder predicted criminal behavior at age fifteen. Male gender also predicted criminal behavior at age fifteen. However, exposure to shooter games did not predict adolescent conduct disorder or criminal behavior. We have found support that suggests that the role of violent video games in the development of youth psychopathology or crime is very little if any. Lack of a relationship between exposure to shooter games and later conduct and criminal behavior problems may be understood within the context of the Catalyst Model. Copyright © 2018 Elsevier Ltd. All rights reserved.

Long working hours and cognitive function: the Whitehall II Study.

PubMed

Virtanen, Marianna; Singh-Manoux, Archana; Ferrie, Jane E; Gimeno, David; Marmot, Michael G; Elovainio, Marko; Jokela, Markus; Vahtera, Jussi; Kivimäki, Mika

2009-03-01

This study examined the association between long working hours and cognitive function in middle age. Data were collected in 1997-1999 (baseline) and 2002-2004 (follow-up) from a prospective study of 2,214 British civil servants who were in full-time employment at baseline and had data on cognitive tests and covariates. A battery of cognitive tests (short-term memory, Alice Heim 4-I, Mill Hill vocabulary, phonemic fluency, and semantic fluency) were measured at baseline and at follow-up. Compared with working 40 hours per week at most, working more than 55 hours per week was associated with lower scores in the vocabulary test at both baseline and follow-up. Long working hours also predicted decline in performance on the reasoning test (Alice Heim 4-I). Similar results were obtained by using working hours as a continuous variable; the associations between working hours and cognitive function were robust to adjustments for several potential confounding factors including age, sex, marital status, education, occupation, income, physical diseases, psychosocial factors, sleep disturbances, and health risk behaviors. This study shows that long working hours may have a negative effect on cognitive performance in middle age.

Long Working Hours and Cognitive Function

PubMed Central

Singh-Manoux, Archana; Ferrie, Jane E.; Gimeno, David; Marmot, Michael G.; Elovainio, Marko; Jokela, Markus; Vahtera, Jussi; Kivimäki, Mika

2009-01-01

This study examined the association between long working hours and cognitive function in middle age. Data were collected in 1997–1999 (baseline) and 2002–2004 (follow-up) from a prospective study of 2,214 British civil servants who were in full-time employment at baseline and had data on cognitive tests and covariates. A battery of cognitive tests (short-term memory, Alice Heim 4-I, Mill Hill vocabulary, phonemic fluency, and semantic fluency) were measured at baseline and at follow-up. Compared with working 40 hours per week at most, working more than 55 hours per week was associated with lower scores in the vocabulary test at both baseline and follow-up. Long working hours also predicted decline in performance on the reasoning test (Alice Heim 4-I). Similar results were obtained by using working hours as a continuous variable; the associations between working hours and cognitive function were robust to adjustments for several potential confounding factors including age, sex, marital status, education, occupation, income, physical diseases, psychosocial factors, sleep disturbances, and health risk behaviors. This study shows that long working hours may have a negative effect on cognitive performance in middle age. PMID:19126590

The contribution of fetal drug exposure to temperament: potential teratogenic effects on neuropsychiatric risk.

PubMed

Weiss, Sandra J; St Jonn-Seed, Mary; Harris-Muchell, Carolyn

2007-08-01

Preliminary evidence indicates that fetal drug exposure may be associated with alterations in temperament. However, studies often do not dissociate the potential effects of drug exposure from other perinatal or environmental factors that could influence temperament phenotypes. High risk children (n = 120) were followed from birth to 6 months of age to determine the effects of fetal drug exposure on temperament, after controlling for the child's gender, gestational age, medical morbidity, ethnicity, and maltreatment as well as the mother's stress, income adequacy, and quality of caregiving. Methods included medical chart review, questionnaires, and videotapes of mother-child interaction. Preliminary analyses indicated that fetal drug exposure was associated with both distractibility and intensity of children's responses to the environment at 6 months of age. After adjusting for potentially confounding variables, drug exposure accounted for 12% of the variance in distractibility but was not a significant predictor in the regression model for intensity. Findings suggest that drug-exposed children may experience difficulty sustaining their focus of attention and be more easily distracted by environmental stimuli than non-drug-exposed children. Results converge with previous research to implicate cortical hyperarousal, stemming from teratogenic effects on the dopaminergic system during fetal development.

Independent association of clustered metabolic risk factors with cardiorespiratory fitness in youth aged 11-17 years.

PubMed

Machado-Rodrigues, Aristides M; Leite, Neiva; Coelho-e-Silva, Manuel J; Martins, Raul A; Valente-dos-Santos, João; Mascarenhas, Luís P G; Boguszewski, Margaret C S; Padez, Cristina; Malina, Robert M

2014-01-01

Although the prevalence of metabolic syndrome (MetS) has increased in youth, the potential independent contribution of cardiorespiratory fitness (CRF) to the clustering of metabolic risk factors has received relatively little attention. This study evaluated associations between the clustering of metabolic risk factors and CRF in a sample of youth. Height, weight, BMI, fasting glucose, insulin, HDL-cholesterol, triglycerides and blood pressures were measured in a cross-sectional sample of 924 youth (402 males, 522 females) of 11-17 years. CRF was assessed using the 20-metre shuttle run test. Physical activity (PA) was measured with a 3-day diary. Outcome variables were statistically normalized and expressed as Z-scores. A MetS risk score was computed as the mean of the Z-scores. Multiple linear regression was used to test associations between CRF and metabolic risk, adjusted for age, sex, BMI, PA and parental education. CRF was inversely associated with MetS after adjustment for potential confounders. After adjusting for BMI, the relationship between CRF and metabolic risk has substantially improved. CRF was independently associated with the clustering of metabolic risk factors in youth of 11-17 years of age.

Understanding logistic regression analysis.

PubMed

Sperandei, Sandro

2014-01-01

Logistic regression is used to obtain odds ratio in the presence of more than one explanatory variable. The procedure is quite similar to multiple linear regression, with the exception that the response variable is binomial. The result is the impact of each variable on the odds ratio of the observed event of interest. The main advantage is to avoid confounding effects by analyzing the association of all variables together. In this article, we explain the logistic regression procedure using examples to make it as simple as possible. After definition of the technique, the basic interpretation of the results is highlighted and then some special issues are discussed.

A Bayesian Framework to Account for Complex Non-Genetic Factors in Gene Expression Levels Greatly Increases Power in eQTL Studies

PubMed Central

Durbin, Richard; Winn, John

2010-01-01

Gene expression measurements are influenced by a wide range of factors, such as the state of the cell, experimental conditions and variants in the sequence of regulatory regions. To understand the effect of a variable of interest, such as the genotype of a locus, it is important to account for variation that is due to confounding causes. Here, we present VBQTL, a probabilistic approach for mapping expression quantitative trait loci (eQTLs) that jointly models contributions from genotype as well as known and hidden confounding factors. VBQTL is implemented within an efficient and flexible inference framework, making it fast and tractable on large-scale problems. We compare the performance of VBQTL with alternative methods for dealing with confounding variability on eQTL mapping datasets from simulations, yeast, mouse, and human. Employing Bayesian complexity control and joint modelling is shown to result in more precise estimates of the contribution of different confounding factors resulting in additional associations to measured transcript levels compared to alternative approaches. We present a threefold larger collection of cis eQTLs than previously found in a whole-genome eQTL scan of an outbred human population. Altogether, 27% of the tested probes show a significant genetic association in cis, and we validate that the additional eQTLs are likely to be real by replicating them in different sets of individuals. Our method is the next step in the analysis of high-dimensional phenotype data, and its application has revealed insights into genetic regulation of gene expression by demonstrating more abundant cis-acting eQTLs in human than previously shown. Our software is freely available online at http://www.sanger.ac.uk/resources/software/peer/. PMID:20463871

Perceived discrimination and health-related quality-of-life: gender differences among older African Americans.

PubMed

Coley, Sheryl L; Mendes de Leon, Carlos F; Ward, Earlise C; Barnes, Lisa L; Skarupski, Kimberly A; Jacobs, Elizabeth A

2017-12-01

Emerging data suggest that African-American women may fare worse than African-American men in health-related quality-of-life (HRQOL). Perceived discrimination is an important contributor to poor health overall among African Americans, but few studies examined the intersecting effects of perceived discrimination and gender in explaining HRQOL disparities. We investigated gender differences in HRQOL and tested whether perceived discrimination accounted for these differences. We examined data from the Chicago Health and Aging Project in which 5652 African-American adults aged 65 and older completed structured questionnaires about demographic and socioeconomic characteristics, HRQOL, perceived discrimination, and health-related variables. Logistic regression models were used to identify associations between perceived discrimination and gender differences in poor HRQOL outcomes (defined as 14+ unhealthy days in overall, physical, or mental health over the past 30 days) when controlling for the other variables. More women reported poor overall HRQOL than men (24 vs. 16% respectively). Higher perceived discrimination was significantly associated with worse overall HRQOL (OR 1.11; 95% CI 1.08, 1.15), with stronger effects for women in overall and mental HRQOL. These gender disparities remained significant until controlling for potentially confounding variables. Perceived discrimination did not account for gender differences in poor physical HRQOL. Perceived discrimination is associated with poor HRQOL in older African Americans, with this association appearing stronger in women than men for mental HRQOL. These findings warrant further investigation of effects of perceived discrimination in gender disparities in overall health, and such research can inform and guide efforts for reducing these disparities.

Cross-Sectional Associations of Depressive Symptom Severity and Functioning with Health Service Use by Older People in Low-and-Middle Income Countries

PubMed Central

Twomey, Conal D.; Prince, Martin; Cieza, Alarcos; Baldwin, David S.; Prina, A. Matthew

2015-01-01

Background: Comprehensive understanding of the determinants of health service use (HSU) by older people with depression is essential for health service planning for an ageing global population. This study aimed to determine the extent to which depressive symptom severity and functioning are associated with HSU by older people with depression in low and middle income countries (LMICs). Methods: A cross-sectional analysis of the 10/66 Dementia Research Group population-based surveys dataset. Participants (n = 4590) were those aged 65 or older, in the clinical range for depressive symptoms (defined as scoring four or more on the EURO-D), living in 13 urban and/or rural catchment areas in nine LMICs. Associations were calculated using Poisson regression and random-effects meta-analysis. Results: After adjustment for confounding variables, (EURO-D) depressive symptom severity was significantly associated with “any community HSU” (Pooled Prevalence Ratios = 1.02; 95% CI = 1.01–1.03) but not hospital admission. Conversely, after adjustment, (WHODAS-II) functioning was significantly associated with hospital admission (Pooled PR = 1.14; 95% CI = 1.02–1.26) but not “any community HSU”. Conclusions: Depressive symptom severity does not explain a large proportion of the variance in HSU by older people with depression in LMICs. The association of functioning with this HSU is worthy of further investigation. In LMICs, variables related to accessibility may be more important correlates of HSU than variables directly related to health problems. PMID:25849540

Correlation of Vitamin D status and orthodontic-induced external apical root resorption.

PubMed

Tehranchi, Azita; Sadighnia, Azin; Younessian, Farnaz; Abdi, Amir H; Shirvani, Armin

2017-01-01

Adequate Vitamin D is essential for dental and skeletal health in children and adult. The purpose of this study was to assess the correlation of serum Vitamin D level with external-induced apical root resorption (EARR) following fixed orthodontic treatment. In this cross-sectional study, the prevalence of Vitamin D deficiency (defined by25-hydroxyvitamin-D) was determined in 34 patients (23.5% male; age range 12-23 years; mean age 16.63 ± 2.84) treated with fixed orthodontic treatment. Root resorption of four maxillary incisors was measured using before and after periapical radiographs (136 measured teeth) by means of a design-to-purpose software to optimize data collection. Teeth with a maximum percentage of root resorption (%EARR) were indicated as representative root resorption for each patient. A multiple linear regression model and Pearson correlation coefficient were used to assess the association of Vitamin D status and observed EARR. P < 0.05 was considered statistically significant. The Pearson coefficient between these two variables was determined about 0.15 ( P = 0.38). Regression analysis revealed that Vitamin D status of the patients demonstrated no significant statistical correlation with EARR, after adjustment of confounding variables using linear regression model ( P > 0.05). This study suggests that Vitamin D level is not among the clinical variables that are potential contributors for EARR. The prevalence of Vitamin D deficiency does not differ in patients with higher EARR. These data suggest the possibility that Vitamin D insufficiency may not contribute to the development of more apical root resorption although this remains to be confirmed by further longitudinal cohort studies.

Predictors of participation in sports after hip and knee arthroplasty.

PubMed

Williams, Daniel H; Greidanus, Nelson V; Masri, Bassam A; Duncan, Clive P; Garbuz, Donald S

2012-02-01

While the primary objective of joint arthroplasty is to improve patient quality of life, pain, and function, younger active patients often demand a return to higher function that includes sporting activity. Knowledge of rates and predictors of return to sports will help inform expectations in patients anticipating return to sports after joint arthroplasty. We measured the rate of sports participation at 1 year using the UCLA activity score and explored 11 variables, including choice of procedure/prosthesis, that might predict return to a high level of sporting activity, when controlling for potential confounding variables. We retrospectively evaluated 736 patients who underwent primary metal-on-polyethylene THA, metal-on-metal THA, hip resurfacing arthroplasty, revision THA, primary TKA, unicompartmental knee arthroplasty, and revision TKA between May 2005 and June 2007. We obtained UCLA activity scores on all patients; we defined high activity as a UCLA score of 7 or more. We evaluated patient demographics (age, sex, BMI, comorbidity), quality of life (WOMAC score, Oxford Hip Score, SF-12 score), and surgeon- and procedural/implant-specific variables to identify factors associated with postoperative activity score. Minimum followup was 11 months (mean, 12.1 months; range, 11-13 months). Preoperative UCLA activity score, age, male sex, and BMI predicted high activity scores. The type of operation and implant characteristics did not predict return to high activity sports. Our data suggest patient-specific factors predict postoperative activity rather than factors specific to type of surgery, implant, or surgeon factors. Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Effects of internal displacement and resettlement on the mental health of Turkish children and adolescents.

PubMed

Erol, Neşe; Simşek, Zeynep; Oner, Ozgür; Munir, Kerim

2005-03-01

To evaluate the effects of internal displacement and resettlement within Turkey on the emotional and behavioral profile of children, age 5-18 after controlling for possible confounding and demographic variables. We conducted a national population survey using a self-weighted, equal probability sample. We compared the CBCL, TRF and YSR responses regarding children with (n = 1644) and without (n = 1855) experience of internal displacement. We examined the effects of gender, age, paternal employment, resettlement, urban residence and physical illness. The children and adolescents with internal displacement had significantly higher internalizing, externalizing and total problem scores on the CBCL and YSR, and higher internalizing scores on the TRF. The effect of displacement was related to higher internalizing problems when factors like physical illness, child age, child gender and urban residence were accounted. The overall effect was small explaining only 0.1-1.5% of the total variance by parent reports, and not evident by teacher reports. To our knowledge the present study is the first to examine Turkish children and adolescents with and without experience of internal displacement. The results are consistent with previous immigration studies: child age, gender, presence of physical illness and urban residence were more important predictors of internalization and externalization problem scores irrespective of informant source.

Regional demographic trends from long-term studies of saguaro (Carnegiea gigantea) across the northern Sonoran Desert

USGS Publications Warehouse

Pierson, Elizabeth A.; Betancourt, Julio L.; Turner, Raymond M.

2013-01-01

Ten saguaro (Carnegiea gigantea) populations in the northern Sonoran Desert were monitored from 1959 to 2005 to discriminate how climate influences plant growth, abundance, reproductive potential, survivorship, age structure and regeneration trends. Thousands of saguaros were measured to determine site-specific growth rates and survivorship through time. Observed growth rates were used to predict the ages of saguaros and reconstruct local and regional regeneration patterns back to the late 18th century. Both growth rates and degree of branching generally tracked temperature and moisture gradients. Site-specific age-height models explained 89-97% of variance in observed ages, with a slope of nearly one. Regeneration was more consistent at sites in the western (hotter/drier) than eastern (cooler/wetter) sites, which exhibited clear multidecadal variability in regeneration rates. Averaged across the region, saguaro regeneration rates were highest from 1780 to 1860, coincident with wet conditions and high Pinus ponderosa recruitment in the highlands. Milder and wetter winters and protection from livestock grazing likely promoted late 20th century regeneration surges at some sites. Predictions of saguaro population dynamics in the 21st century likely will be confounded by the saguaro's episodic and asynchronous regeneration, continued urbanization, ongoing grass invasions and associated wildfires, and changing climate.

Risperidone and Risk of Gynecomastia in Young Men.

PubMed

Etminan, Mahyar; Carleton, Bruce; Brophy, James M

2015-11-01

The purpose of this study was to quantify the risk of gynecomastia with risperidone in adolescent and young adult males. We created a cohort of males 15-25 years of age from the IMS LifeLink database, and conducted a case-control study within the cohort by identifying all new cases of gynecomastia. For each case, 10 controls were selected and matched to the cases by age, follow-up, and calendar times (cases and controls had the same follow up time and cohort entry date). Rate ratios (RR) for current use of risperidone were computed adjusting for potential confounding variables. First diagnosis of gynecomastia was made based on International Classification of Diseases, 9th revision (ICD-9) for gynecomastia. There were 401,924 males ages 15-25 in the primary cohort. There were 1556 cases of gynecomastia and 15,560 corresponding controls. Current users of risperidone had approximately four times the risk of developing gynecomastia than non-users (RR=3.91, 95% CI=2.01-7.62). When the analysis was stratified to children and adolescents (≤18 years of age) taking risperidone, the risk of gynecomastia was five times higher than for non-users (RR=5.44, 95% CI=1.50-19.74). Risperidone is associated with an increase with the risk of gynecomastia in adolescent and young adult males.

Household Food Insecurity May Predict Underweightand Wasting among Children Aged 24-59 Months.

PubMed

Abdurahman, Ahmed A; Mirzaei, Khadijeh; Dorosty, Ahmed Reza; Rahimiforoushani, A; Kedir, Haji

2016-01-01

The aim of this study was to examine the association between household food insecurity and nutritional status among children aged 24-59 months in Haromaya District. Children (N = 453) aged 24-59 months were recruited in a community-based cross-sectional survey with a representative sample of households selected by a multistage sampling procedure in Haromaya District. Household Food Insecurity Access Scale and anthropometry were administered. Multinomial logistic regression models were applied to select variables that are candidate for multivariable model. The prevalences of stunting, underweight, and wasting among children aged 24-59 months were 61.1%, 28.1%, and 11.8%, respectively. The mean household food insecurity access scale score was 3.34, and 39.7% of households experienced some degree of food insecurity. By logistic regression analysis and after adjusting for the confounding factors, household food insecurity was significantly predictive of underweight (AOR = 2.48, CI = 1.17-5.24, p = .05) and chronic energy deficiency (AOR = 0.47, CI = 0.23-0.97, p = .04) and marginally significant for wasting (AOR = 0.53, CI = 0.27-1.03, p = .06). It is concluded that household food security improves child growth and nutritional status.

Adolescent over-general memory, life events and mental health outcomes: Findings from a UK cohort study

PubMed Central

Crane, Catherine; Heron, Jon; Gunnell, David; Lewis, Glyn; Evans, Jonathan; Williams, J. Mark G.

2016-01-01

Previous research suggesting that over-general memory (OGM) may moderate the effect of life events on depressive symptoms and suicidality has sampled older adolescents or adults, or younger adolescents in high-risk populations, and has been conducted over relatively short follow-up periods. The authors examined the relationship between OGM at age 13 and life events and mental health outcomes (depression, self-harm, suicidal ideation and planning) at age 16 years within a sample of 5792 adolescents participating in the Avon Longitudinal Study of Parents and Children (ALSPAC), approximately 3800 of whom had also provided data on depression and self-harm. There was no clear evidence of either direct or interactive effects of OGM at age 13 on levels of depression at age 16. Similarly there was no clear evidence of either direct or interactive effects of OGM on suicidal ideation and self-harm. Although there was some evidence that over-general autobiographical memory was associated with reduced risk of suicidal planning and increased risk of self-harm, these associations were absent when confounding variables were taken into account. The findings imply that although OGM is a marker of vulnerability to depression and related psychopathology in high-risk groups, this cannot be assumed to generalise to whole populations. PMID:25716137

Adolescent over-general memory, life events and mental health outcomes: Findings from a UK cohort study.

PubMed

Crane, Catherine; Heron, Jon; Gunnell, David; Lewis, Glyn; Evans, Jonathan; Williams, J Mark G

2016-01-01

Previous research suggesting that over-general memory (OGM) may moderate the effect of life events on depressive symptoms and suicidality has sampled older adolescents or adults, or younger adolescents in high-risk populations, and has been conducted over relatively short follow-up periods. The authors examined the relationship between OGM at age 13 and life events and mental health outcomes (depression, self-harm, suicidal ideation and planning) at age 16 years within a sample of 5792 adolescents participating in the Avon Longitudinal Study of Parents and Children (ALSPAC), approximately 3800 of whom had also provided data on depression and self-harm. There was no clear evidence of either direct or interactive effects of OGM at age 13 on levels of depression at age 16. Similarly there was no clear evidence of either direct or interactive effects of OGM on suicidal ideation and self-harm. Although there was some evidence that over-general autobiographical memory was associated with reduced risk of suicidal planning and increased risk of self-harm, these associations were absent when confounding variables were taken into account. The findings imply that although OGM is a marker of vulnerability to depression and related psychopathology in high-risk groups, this cannot be assumed to generalise to whole populations.

Associations between poor sleep quality and psychosocial stress with obesity in reproductive-age women of lower socioeconomic status.

PubMed

Tom, Sarah E; Berenson, Abbey B

2013-01-01

Prior studies have not examined the role of psychosocial stress in the relationship between poor sleep quality and obesity among women of lower socioeconomic status (SES). We tested the following hypotheses in a sample of reproductive-age women of lower SES: 1) Poor sleep quality is related to increased risk of obesity, and 2) psychosocial stress confounds this association between poor sleep quality and obesity. A total of 927 women age 16 to 40 years attending public health clinics in Southeastern Texas provided information on the Pittsburgh Sleep Quality Index and sociodemographic and health characteristics, including the Perceived Stress Scale. Height, weight, and waist circumference (WC) were measured in clinic. A series of models examined the associations between sleep disturbance, perceived stress, and weight outcomes, accounting for potential confounding factors. Nearly 30% of women were overweight, and 35% were obese. Half of women had a WC of greater than 35 inches. Most women had poor sleep quality and high levels of stress. Sleep quality and perceived stress were not related to body mass index category or WC in models that adjusted for age and race/ethnicity. Adjusting for potential confounding factors did not alter results. Perceived stress did not modify the association between sleep quality and weight outcomes. Poor sleep quality and psychosocial stress were not related to weight in reproductive-aged women of lower SES. However, poor sleep quality, high stress, overweight, and obesity were common in this group. Copyright © 2013 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

Network Mendelian randomization: using genetic variants as instrumental variables to investigate mediation in causal pathways

PubMed Central

Burgess, Stephen; Daniel, Rhian M; Butterworth, Adam S; Thompson, Simon G

2015-01-01

Background: Mendelian randomization uses genetic variants, assumed to be instrumental variables for a particular exposure, to estimate the causal effect of that exposure on an outcome. If the instrumental variable criteria are satisfied, the resulting estimator is consistent even in the presence of unmeasured confounding and reverse causation. Methods: We extend the Mendelian randomization paradigm to investigate more complex networks of relationships between variables, in particular where some of the effect of an exposure on the outcome may operate through an intermediate variable (a mediator). If instrumental variables for the exposure and mediator are available, direct and indirect effects of the exposure on the outcome can be estimated, for example using either a regression-based method or structural equation models. The direction of effect between the exposure and a possible mediator can also be assessed. Methods are illustrated in an applied example considering causal relationships between body mass index, C-reactive protein and uric acid. Results: These estimators are consistent in the presence of unmeasured confounding if, in addition to the instrumental variable assumptions, the effects of both the exposure on the mediator and the mediator on the outcome are homogeneous across individuals and linear without interactions. Nevertheless, a simulation study demonstrates that even considerable heterogeneity in these effects does not lead to bias in the estimates. Conclusions: These methods can be used to estimate direct and indirect causal effects in a mediation setting, and have potential for the investigation of more complex networks between multiple interrelated exposures and disease outcomes. PMID:25150977

Assessing the impact of adolescent pregnancy and the premarital conception stress complex on birth weight among young mothers in Gibraltar's civilian community.

PubMed

Sawchuk, L A; Burke, S D; Benady, S

1997-10-01

The objective of this study was to assess the impact of young maternal age and the timing of conception on birth weight among primiparous women living in Gibraltar. The data for this study were derived from a population of 295 primiparous women who gave birth under 25 years of age. Only married women who had no previous maternal history and delivered live singleton newborns between 1980 and 1984 were included. The confounding effects of gestation length, sex, and socio-economic status on birth weight were taken into account using the multivariate technique of multiple classification analysis. A conception timing variable was constructed and partitioned into four groups which represented the separate and joint effects of maternal age and prenuptial stress on birth weight. The overall mean birth weight was 3344.15 g. After controlling for the specified factors and covariate, the infants of older mother (> 19) who conceived after marriage weighed 57.78 g above the referent group mean. Older mothers who conceived a child before marriage delivered infants weighing 75.67 below the grand mean. Young mother (< 20) who conceived within marriage had infants who weighed 37.32 g less than the grand mean. Infants delivered by young mothers who conceived before marriage weighed 133.66 g less than the overall mean birth weight. The only significant group difference detected within the conception timing variable was between young mothers who conceived before marriage versus older mothers who conceived after marriage. Premarital conception is identified as a risk factor for lower infant birth weights among mothers under 20 years of age. This study emphasizes the need to take into account the effects of culturally mediated behavior on the pregnancy experience of young women.

[Correlates of change in cognitive function during a two-year follow-up period in a comprehensive health examination for the community-dwelling elderly for the prevention of geriatric syndromes and bed-ridden state].

PubMed

Iwasa, Hajime; Suzuki, Takao; Yoshida, Yuko; Kwon, Jinhee; Yoshida, Hideyo; Kim, Hunkyung; Sugiura, Miho; Furuna, Taketo

2006-11-01

We explored correlates of change in cognitive function during a two-year follow-up period among the community-dwelling elderly in Japan, using a population-based prospective approach. The participants analyzed in the present study were 260 men and 222 women aged 70 to 84 years at baseline, living in an urban Japanese community. Data such as change in cognitive function during two years (calculated by subtracting baseline Mini-Mental State Examination [MMSE] score from follow-up MMSE score: a negative value means a decrease in MMSE scores during the two-year period) as an outcome variable, age, education, hearing and vision problems, IADL deficit (measured by the Tokyo Metropolitan Institute of Gerontology of Index of Competence), problems related to memory complaint, living alone, hemoglobin level, as explanatory variables, and the baseline MMSE score, depressive status (measured by the Mini-International Neuropsychiatric Interview), chronic conditions (hypertension, stroke, and diabetes mellitus) as covariates, were collected during a comprehensive health examination survey for the elderly. We conducted multivariate regression analysis by genders to explore correlates of change in cognitive function. The results showed that higher age (beta = -0.18), presence of hearing problem (beta = -0.21), presence of IADL deficit (beta = -0.15), and memory complaint (beta = -0.20) in men, and higher age (beta = -0.27), low education level (beta = -0.25) and lower hemoglobin level (beta = 0.16) in women, were significantly associated with change in cognitive function when adjusting for the potential confounders. These factors may be reliable predictors for cognitive decline.

CerebroMatic: A Versatile Toolbox for Spline-Based MRI Template Creation

PubMed Central

Wilke, Marko; Altaye, Mekibib; Holland, Scott K.

2017-01-01

Brain image spatial normalization and tissue segmentation rely on prior tissue probability maps. Appropriately selecting these tissue maps becomes particularly important when investigating “unusual” populations, such as young children or elderly subjects. When creating such priors, the disadvantage of applying more deformation must be weighed against the benefit of achieving a crisper image. We have previously suggested that statistically modeling demographic variables, instead of simply averaging images, is advantageous. Both aspects (more vs. less deformation and modeling vs. averaging) were explored here. We used imaging data from 1914 subjects, aged 13 months to 75 years, and employed multivariate adaptive regression splines to model the effects of age, field strength, gender, and data quality. Within the spm/cat12 framework, we compared an affine-only with a low- and a high-dimensional warping approach. As expected, more deformation on the individual level results in lower group dissimilarity. Consequently, effects of age in particular are less apparent in the resulting tissue maps when using a more extensive deformation scheme. Using statistically-described parameters, high-quality tissue probability maps could be generated for the whole age range; they are consistently closer to a gold standard than conventionally-generated priors based on 25, 50, or 100 subjects. Distinct effects of field strength, gender, and data quality were seen. We conclude that an extensive matching for generating tissue priors may model much of the variability inherent in the dataset which is then not contained in the resulting priors. Further, the statistical description of relevant parameters (using regression splines) allows for the generation of high-quality tissue probability maps while controlling for known confounds. The resulting CerebroMatic toolbox is available for download at http://irc.cchmc.org/software/cerebromatic.php. PMID:28275348

CerebroMatic: A Versatile Toolbox for Spline-Based MRI Template Creation.

PubMed

Wilke, Marko; Altaye, Mekibib; Holland, Scott K

2017-01-01

Brain image spatial normalization and tissue segmentation rely on prior tissue probability maps. Appropriately selecting these tissue maps becomes particularly important when investigating "unusual" populations, such as young children or elderly subjects. When creating such priors, the disadvantage of applying more deformation must be weighed against the benefit of achieving a crisper image. We have previously suggested that statistically modeling demographic variables, instead of simply averaging images, is advantageous. Both aspects (more vs. less deformation and modeling vs. averaging) were explored here. We used imaging data from 1914 subjects, aged 13 months to 75 years, and employed multivariate adaptive regression splines to model the effects of age, field strength, gender, and data quality. Within the spm/cat12 framework, we compared an affine-only with a low- and a high-dimensional warping approach. As expected, more deformation on the individual level results in lower group dissimilarity. Consequently, effects of age in particular are less apparent in the resulting tissue maps when using a more extensive deformation scheme. Using statistically-described parameters, high-quality tissue probability maps could be generated for the whole age range; they are consistently closer to a gold standard than conventionally-generated priors based on 25, 50, or 100 subjects. Distinct effects of field strength, gender, and data quality were seen. We conclude that an extensive matching for generating tissue priors may model much of the variability inherent in the dataset which is then not contained in the resulting priors. Further, the statistical description of relevant parameters (using regression splines) allows for the generation of high-quality tissue probability maps while controlling for known confounds. The resulting CerebroMatic toolbox is available for download at http://irc.cchmc.org/software/cerebromatic.php.

Depression among Arabs and Jews in Israel: a population-based study.

PubMed

Kaplan, Giora; Glasser, Saralee; Murad, Havi; Atamna, Ahmed; Alpert, Gershon; Goldbourt, Uri; Kalter-Leibovici, Ofra

2010-10-01

Depression is the second most common chronic disorder seen by primary care physicians. Risk factors associated with depression include medical and psychosocial factors. While in Israel, the rate and risk factors for depression are considered similar to those in other Western countries, population-based data are limited. The present study aims to estimate the prevalence of depression among Jews and Muslim Arabs, and to consider possible associations with demographic, socioeconomic, and health factors. The study group (N = 872) was equally divided according to ethnicity, gender, and age group. Depression was measured by the Harvard Department of Psychiatry National Depression Screening Day Scale (HANDS). The rate of depression scores in the likely/very likely range was 2.5 times higher among Arabs than among Jews (24.9 vs. 10.6%; P < 0.001). Women were more likely to express symptoms of depressive episode than were men (22.0 vs. 13.6%; P = 0.001), and the depression rate increased with age, from 11.0% in the youngest group (26-35) to 25.0% in the oldest (P = 0.001). The rate of increase in depression by age was different for the genders, rising more steeply for women than for men. However, the age-gender differential was not identical for the two ethnic groups. The differences in depression prevalence between Arabs and Jews were maintained after controlling for confounding variables, except that when controlling for education, the difference between the ethnic groups was no longer significant. After adjusting for all variables in the analysis, no significant association remained between ethnicity and depression (OR = 0.80; 95% CI = 0.45-1.40).

Retrospective lifetime dietary patterns predict cognitive performance in community-dwelling older Australians.

PubMed

Hosking, Diane E; Nettelbeck, Ted; Wilson, Carlene; Danthiir, Vanessa

2014-07-28

Dietary intake is a modifiable exposure that may have an impact on cognitive outcomes in older age. The long-term aetiology of cognitive decline and dementia, however, suggests that the relevance of dietary intake extends across the lifetime. In the present study, we tested whether retrospective dietary patterns from the life periods of childhood, early adulthood, adulthood and middle age predicted cognitive performance in a cognitively healthy sample of 352 older Australian adults >65 years. Participants completed the Lifetime Diet Questionnaire and a battery of cognitive tests designed to comprehensively assess multiple cognitive domains. In separate regression models, lifetime dietary patterns were the predictors of cognitive factor scores representing ten constructs derived by confirmatory factor analysis of the cognitive test battery. All regression models were progressively adjusted for the potential confounders of current diet, age, sex, years of education, English as native language, smoking history, income level, apoE ɛ4 status, physical activity, other past dietary patterns and health-related variables. In the adjusted models, lifetime dietary patterns predicted cognitive performance in this sample of older adults. In models additionally adjusted for intake from the other life periods and mechanistic health-related variables, dietary patterns from the childhood period alone reached significance. Higher consumption of the 'coffee and high-sugar, high-fat extras' pattern predicted poorer performance on simple/choice reaction time, working memory, retrieval fluency, short-term memory and reasoning. The 'vegetable and non-processed' pattern negatively predicted simple/choice reaction time, and the 'traditional Australian' pattern positively predicted perceptual speed and retrieval fluency. Identifying early-life dietary antecedents of older-age cognitive performance contributes to formulating strategies for delaying or preventing cognitive decline.

Does arterial hypertension influence the onset of Huntington's disease?

PubMed Central

Fullaondo, Asier; Alkorta-Aranburu, Gorka; García-Barcina, María; Roos, Raymund A. C.; Hjermind, Lena E.; Frontali, Marina; Reilmann, Ralf; Rickards, Hugh; Zubiaga, Ana M.; Aguirre, Ana

2018-01-01

Huntington’s disease (HD) age of onset (AO) is mainly determined by the length of the CAG repeat expansion in the huntingtin gene. The remaining AO variability has been attributed to other little-known factors. A factor that has been associated with other neurodegenerative diseases is arterial hypertension (AHT). The aim of this study is to evaluate the contribution of AHT to the AO of HD. We used data from a cohort of 630 European HD patients with adult onset collected by the REGISTRY project of the European Huntington’s Disease Network. Multiple linear regression and ANOVA, controlling for the CAG repeat number of the expanded allele (CAGexp) of each patient, were performed to assess the association between the AHT condition and the AO of the motor symptoms (mAO). The results showed a significant association between AHT and mAO, especially when we only considered the patients diagnosed with AHT prior to manifesting any HD signs (pre-HD AHT). Remarkably, despite the low number of cases, those patients developed motor symptoms 5–8 years later than normotensive patients in the most frequent CAGexp range (40–44). AHT is an age-related condition and consequently, the age of the patient at the time of data collection could be a confounder variable. However, given that most pre-HD AHT patients included in our study had started treatment with antihypertensive drugs prior to the onset of HD, and that antihypertensive drugs have been suggested to confer a neuroprotective effect in other neurodegenerative diseases, raises the interest in elucidating the impact of AHT and/or AHT treatment in HD age of onset in further studies. A confirmation of our results in a larger sample set would open the possibility to significantly improve HD management. PMID:29791508

Family pet ownership during childhood: findings from a UK birth cohort and implications for public health research.

PubMed

Westgarth, Carri; Heron, Jon; Ness, Andy R; Bundred, Peter; Gaskell, Rosalind M; Coyne, Karen P; German, Alexander J; McCune, Sandra; Dawson, Susan

2010-10-01

In developed nations, approximately half of household environments contain pets. Studies of Human-Animal Interaction (HAI) have proposed that there are health benefits and risks associated with pet ownership. However, accurately demonstrating and understanding these relationships first requires a better knowledge of factors associated with ownership of different pet types. A UK birth cohort, the Avon Longitudinal Study of Parents and Children (ALSPAC), were used to collect pet ownership data from the mothers, from gestation to child age 10 years old. 14,663 children were included in the study, of which mothers of 13,557 reported pet information at gestation, and 7,800 by age 10. Pet types recorded include cat, dog, rabbit, rodent, bird, fish and tortoise/turtle. The dataset also contains a number of demographic, socioeconomic and behavioural variables relevant to human health behaviour. Logistic regression was used to build multivariable models for ownership of each pet type at age 7 years. Family pet ownership increased during childhood, in particular rabbits, rodents and fish. A number of socioeconomic and demographic factors were associated with ownership of different pet types and the effects differed depending on the pet type studied. Variables which require consideration by researchers include gender, presence of older siblings, ethnicity, maternal and paternal education, maternal and paternal social class, maternal age, number of people in the household, house type, and concurrent ownership of other pets. Whether the mother had pets during her childhood was a strong predictor of pet ownership in all models. In HAI studies, care should be taken to control for confounding factors, and to treat each pet type individually. ALSPAC and other similar birth cohorts can be considered a potential resource for research into the effects of pet ownership during childhood.

Family Pet Ownership during Childhood: Findings from a UK Birth Cohort and Implications for Public Health Research

PubMed Central

Westgarth, Carri; Heron, Jon; Ness, Andy R.; Bundred, Peter; Gaskell, Rosalind M.; Coyne, Karen P.; German, Alexander J.; McCune, Sandra; Dawson, Susan

2010-01-01

In developed nations, approximately half of household environments contain pets. Studies of Human-Animal Interaction (HAI) have proposed that there are health benefits and risks associated with pet ownership. However, accurately demonstrating and understanding these relationships first requires a better knowledge of factors associated with ownership of different pet types. A UK birth cohort, the Avon Longitudinal Study of Parents and Children (ALSPAC), were used to collect pet ownership data from the mothers, from gestation to child age 10 years old. 14,663 children were included in the study, of which mothers of 13,557 reported pet information at gestation, and 7,800 by age 10. Pet types recorded include cat, dog, rabbit, rodent, bird, fish and tortoise/turtle. The dataset also contains a number of demographic, socioeconomic and behavioural variables relevant to human health behaviour. Logistic regression was used to build multivariable models for ownership of each pet type at age 7 years. Family pet ownership increased during childhood, in particular rabbits, rodents and fish. A number of socioeconomic and demographic factors were associated with ownership of different pet types and the effects differed depending on the pet type studied. Variables which require consideration by researchers include gender, presence of older siblings, ethnicity, maternal and paternal education, maternal and paternal social class, maternal age, number of people in the household, house type, and concurrent ownership of other pets. Whether the mother had pets during her childhood was a strong predictor of pet ownership in all models. In HAI studies, care should be taken to control for confounding factors, and to treat each pet type individually. ALSPAC and other similar birth cohorts can be considered a potential resource for research into the effects of pet ownership during childhood. PMID:21139856

Quantitative evaluation of light scattering intensities of the crystalline lens for radiation related minimal change in interventional radiologists: a cross-sectional pilot study.

PubMed

Abe, Toshi; Furui, Shigeru; Sasaki, Hiroshi; Sakamoto, Yasuo; Suzuki, Shigeru; Ishitake, Tatsuya; Terasaki, Kinuyo; Kohtake, Hiroshi; Norbash, Alexander M; Behrman, Richard H; Hayabuchi, Naofumi

2013-03-01

To evaluate low-dose X-ray radiation effects on the eye by measuring the amount of light scattering in specific regions of the lens, we compared exposed subjects (interventional radiologists) with unexposed subjects (employees of medical service companies), as a pilot study. According to numerous exclusionary rules, subjects with confounding variables contributing to cataract formation were excluded. Left eye examinations were performed on 68 exposed subjects and 171 unexposed subjects. The eye examinations consisted of an initial screening examination, followed by Scheimpflug imaging of the lens using an anterior eye segment analysis system. The subjects were assessed for the quantity of light scattering intensities found in each of the six layers of the lens. Multiple stepwise regression analyses were performed with the stepwise regression for six variables: age, radiation exposure, smoking, drinking, wearing glasses and workplace. In addition, an age-matched comparison between exposed and unexposed subjects was performed. Minimal increased light scattering intensity in the posterior subcapsular region showed statistical significance. Our results indicate that occupational radiation exposure in interventional radiologists may affect the posterior subcapsular region of the lens. Since by its very nature this retrospective study had many limitations, further well-designed studies concerning minimal radiation-related lens changes should be carried out in a low-dose exposure group.

Social capital, the miniaturization of community and high alcohol consumption: a population-based study.

PubMed

Lindström, Martin

2005-01-01

To study the impact of social participation, trust, and the miniaturization of community, i.e. high social participation/low trust, on the risk of high alcohol consumption. The Scania 2000 public health survey is a cross-sectional, postal questionnaire study. A total of 13 604 persons aged 18-80 years were included. A logistic regression model was used to investigate the association between the social capital variables and high alcohol consumption (168.0 g/week or more for men and 108.0 g/week or more for women). The multivariate analyses analysed the importance of confounders (age, country of origin, education, and economic stress) on the risk of high alcohol consumption according to the social capital variables. A 14.0% proportion of all men and 7.8% of all women had an alcohol consumption above recommended levels. High alcohol consumption above recommended levels was not associated with social participation but negatively associated with trust among men. The miniaturization of community category, i.e. high social participation/low trust, had significantly higher risks of high alcohol consumption compared to the high social capital (high social participation/high trust) category among men. High social participation combined with low trust, i.e. the miniaturization of community, is positively associated high alcohol consumption among men. A structural/social factor which may affect the amount of alcohol consumed has thus been identified in this study.

Sleep duration differences between children of migrant and native origins.

PubMed

Labree, L J W Wim; van de Mheen, H Dike; Rutten, F F H Frans; Rodenburg, G Gerda; Koopmans, G T Gerrit; Foets, M Marleen

To explore whether primary school children of migrant and native Dutch origins differ regarding their sleep duration per night, a risk for overweight and obesity, and to determine to what degree differences in parenting styles contribute to these differences. A cross-sectional survey, including 1,943 children aged 8-9 years old and their primary caregivers, was performed. Data were collected from primary schools in cities and adjacent municipalities in The Netherlands: Eindhoven and Rotterdam. The outcome measure was mean sleep duration per night. The main independent variable was migrant background, based on the country of birth of the parents. A possible mediating variable was parenting style (rejecting, neglecting, permissive, authoritarian, authoritative). Age and sex of the child as well as parental socioeconomic status, as indicated by educational level, were added as confounders. Dutch children have the highest sleep duration: more than 11 h (mean = 670.1; SD = 27.7). All migrant children show less than 11 h of sleep per night. Migrant children of non-Western origin, especially Turkish and Moroccan children, show the lowest sleep duration per night. Parenting styles do not contribute to these differences. Migrant background is associated with sleep duration. As children of migrant origin are, in general, at higher risk for overweight and obesity and sleep duration is regarded as a risk factor for overweight and obesity, further investigation of this association is needed.

The effect of anxiety on heart rate variability, depression, and sleep in chronic obstructive pulmonary disease.

PubMed

Suh, Sooyeon; Ellis, Robert J; Sollers, John J; Thayer, Julian F; Yang, Hae-Chung; Emery, Charles F

2013-05-01

The current study investigates heart rate variability (HRV) responses to a psychosocial stressor in chronic obstructive pulmonary disease (COPD) patients, and the potential role of anxiety as a confounding factor in this relationship. Additionally, this study also investigates the influence of anxiety on sleep and depressive symptoms among COPD patients. The study utilized a 2 (disease status)×2 (anxiety group) factorial design examining HRV associated with anxiety symptoms and COPD during a standardized acute social stress task. Participants (mean age 59.1±11.2 years; 50% female) completed pulmonary function testing, HRV monitoring, and self-report questionnaires assessing psychological factors. 30 COPD patients were age- and gender-matched with 30 healthy controls. HRV response to a psychosocial stressor among participants with higher anxiety (both COPD and healthy) reflected autonomic dysregulation in both time and frequency domains that was not evident among non-anxious participants. COPD participants with higher anxiety reported greater symptoms of depression and poorer sleep quality than did COPD participants with low anxiety. Anxiety is associated with dysregulated HRV response to a psychosocial stressor, but the negative influence of anxiety and COPD on autonomic function did not appear to be additive. Comorbid anxiety in patients with COPD is associated with increased behavioral and psychological symptoms of distress. Copyright © 2013 Elsevier Inc. All rights reserved.

Neuropsychological differences between men and women with Alzheimer's disease.

PubMed

Ryan, Joseph J; Glass Umfleet, Laura; Kreiner, David S; Fuller, Amanda M; Paolo, Anthony M

2018-04-01

It has been suggested that men and women with Alzheimer's disease (AD) at comparable levels of global cognitive impairment perform differently on neuropsychological measures. Such differences may have practical implications for designing cognitive interventions that address symptoms of dementia. We compared men (n = 86) and women (n = 96) with AD on tests of immediate and delayed prose memory, verbal fluency, semantic fluency, semantic memory and confrontation naming. Mean years for age, education and duration of illness were 70.81 (SD = 7.55), 13.37 (SD = 3.38) and 2.17 (SD = 1.72) for men and 73.11(SD = 8.53), 12.27 (SD = 2.86) and 2.42 (SD = 1.92) for women. The groups were comparable in global cognitive functioning as indicated by Dementia Rating Scale total scores for men of 89.27 (SD = 29.80) and women of 90.86 (SD = 30.20). Men earned significantly better scores in immediate prose memory, semantic verbal fluency, semantic memory and response naming. Men and women performed similarly on the remaining tests. When the variables of age, education and duration of disease were controlled, the significant effect of gender was maintained only on tests of semantic fluency, semantic memory and confrontation naming. The hypothesis of the study was partially confirmed in that women with AD evidenced greater impairment than men with AD on three of six neuropsychological measures even after potentially confounding variables were controlled.

Elder abuse and its medical outcomes in older Chinese people with cognitive and physical impairments.

PubMed

Fang, Boye; Yan, Elsie; Chan, Ko Ling; Ip, Partick

2018-05-04

Elder abuse poses a major public health threat considering the ongoing rapid aging of the global population. This study investigates the association between elder abuse by family caregivers and medical outcomes among older Chinese patients with cognitive and physical impairments in the People's Republic of China. Using cross-sectional design, 1002 older patients (aged 55 y and older) and their family caregivers were recruited from 3 grade A hospitals in Guangdong Province. The major independent variable is caregiver-reported elder abuse, while outcome variables include cardiovascular disease, cerebrovascular disease, chronic obstructive pulmonary disease, peptic ulcer, digestive disorder, chronic hepatic disease, chronic renal disease, metabolic disease, acute inflammation, joint disease, tumor, and general injury. The prevalence of these medical conditions among patients who were abused and those who were not were compared using descriptive analyses and chi-square tests, and logistic regression was used to establish the relevant independent associations. A total of 429 (42.8%) older persons have experienced physical or psychological abuse over the past 12 months. After adjusting for potential confounders, abused older persons were more susceptible to cardiovascular disease, chronic obstructive pulmonary disease, peptic ulcer, digestive disorder, metabolic disease, acute inflammation, tumor, and injuries. Elder abuse is associated with various major medical morbidities. Interdisciplinary cooperation is necessary to identify and reduce the adverse physiological consequences in victims. Copyright © 2018 John Wiley & Sons, Ltd.

The association between acculturation and hypertension in a multiethnic sample of US adults.

PubMed

Teppala, Srinivas; Shankar, Anoop; Ducatman, Alan

2010-01-01

Previous studies analyzing acculturation and cardiovascular risk were restricted to individual race/ethnic groups and did not fully account for potential confounders. We examined the independent association between acculturation and hypertension in a contemporary multiethnic sample that included white, black, Latino, and Asian individuals. We examined 51,048 participants in the 2007 California Health Interview Survey who were >18 years, 59.5% of whom were women. The main exposure-of-interest was acculturation score, a summary measure of the additive effect of 4 variables (country of birth, parents' country of birth, language at home, and duration of stay in the United States) ranged from 0 (least acculturation) to 4 (highest acculturation). We found that increased acculturation was associated with hypertension, independent of age, gender, race/ethnicity, education, smoking, alcohol, physical activity, body mass index, and diabetes. Compared with those with the lowest acculturation (score of 0), the multivariable odds ratio (95% confidence interval) of hypertension among those with the highest acculturation (score of 4) was 1.78 (1.50-2.11). This association between acculturation and hypertension was consistent in subgroup analyses by gender, education, smoking, alcohol intake, and body mass index. Increased Western acculturation was found to be positively associated with hypertension in a multiethnic sample, independent of confounders. Copyright © 2010 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Birth Weight, Physical Morbidity, and Mortality: A Population-based Sibling-Comparison Study

PubMed Central

Class, Quetzal A.; Rickert, Martin E.; Lichtenstein, Paul; D'Onofrio, Brian M.

2014-01-01

Associations between low birth weight (≤2,500 g) and increased risk of mortality and morbidity provided the foundation for the “developmental origins of health and disease” hypothesis. Previous between-family studies could not control for unmeasured confounders. Therefore, we compared differentially exposed siblings to estimate the extent to which the associations were due to uncontrolled factors. Our population cohort included 3,291,773 persons born in Sweden from 1973 to 2008. Analyses controlled for gestational age, among other covariates, and considered birth weight as both an ordinal and a continuous variable. Outcomes included mortality after 1 year, cardiac-related death, hypertension, ischemic heart disease, pulmonary circulation problems, stroke, and type 2 diabetes mellitus. We fitted fixed-effects models to compare siblings and conducted sensitivity analyses to test alternative explanations. Across the population, the lower the birth weight, the greater the risk of mortality (e.g., cardiac-related death (low birth weight hazard ratio = 2.69, 95% confidence interval: 2.05, 3.53)) and morbidity (e.g., type 2 diabetes mellitus (low birth weight hazard ratio = 1.79, 95% confidence interval: 1.50, 2.14)) outcomes in comparison with normal birth weight. All associations were independent of shared familial confounders and measured covariates. Results emphasize the importance of birth weight as a risk factor for subsequent mortality and morbidity. PMID:24355331

Consanguinity, prematurity, birth weight and pregnancy loss: a prospective cohort study at four primary health center areas of Karnataka, India.

PubMed

Bellad, M B; Goudar, S S; Edlavitch, S A; Mahantshetti, N S; Naik, V; Hemingway-Foday, J J; Gupta, M; Nalina, H R; Derman, R; Moss, N; Kodkany, B S

2012-06-01

To determine whether consanguinity adversely influences pregnancy outcome in South India, where consanguinity is a common means of family property retention. Data were collected from a prospective cohort of 647 consenting women, consecutively registered for antenatal care between 14 and 18 weeks gestation, in Belgaum district, Karnataka in 2005. Three-generation pedigree charts were drawn for consanguineous participants. χ (2)-Test and Student's t-test were used to assess categorical and continuous data, respectively, using SPSS version 14. Multivariate logistic regression adjusted for confounding variables. Overall, 24.1% of 601 women with singleton births and outcome data were consanguineous. Demographic characteristics between study groups were similar. Non-consanguineous couples had fewer stillbirths (2.6 vs 6.9% P=0.017; adjusted P=0.050), miscarriages (1.8 vs 4.1%, P=0.097; adjusted P=0.052) and lower incidence of birth weight <2500 g (21.8 vs 29.5%, P=0.071, adjusted P=0.044). Gestation <37 weeks was 6.2% in both the groups. Adjusted for consanguinity and other potential confounders, age <20 years was protective of stillbirth (P=0.01), pregnancy loss (P=0.023) and preterm birth (P=0.013), whereas smoking (P=0.015) and poverty (P=0.003) were associated with higher rates of low birth weight. Consanguinity significantly increases pregnancy loss and birth weight <2500 g.

Phosphate binder use and mortality among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS): evaluation of possible confounding by nutritional status.

PubMed

Lopes, Antonio Alberto; Tong, Lin; Thumma, Jyothi; Li, Yun; Fuller, Douglas S; Morgenstern, Hal; Bommer, Jürgen; Kerr, Peter G; Tentori, Francesca; Akiba, Takashi; Gillespie, Brenda W; Robinson, Bruce M; Port, Friedrich K; Pisoni, Ronald L

2012-07-01

Poor nutritional status and both hyper- and hypophosphatemia are associated with increased mortality in maintenance hemodialysis (HD) patients. We assessed associations of phosphate binder prescription with survival and indicators of nutritional status in maintenance HD patients. Prospective cohort study (DOPPS [Dialysis Outcomes and Practice Patterns Study]), 1996-2008. 23,898 maintenance HD patients at 923 facilities in 12 countries. Patient-level phosphate binder prescription and case-mix-adjusted facility percentage of phosphate binder prescription using an instrumental-variable analysis. All-cause mortality. Overall, 88% of patients were prescribed phosphate binders. Distributions of age, comorbid conditions, and other characteristics showed small differences between facilities with higher and lower percentages of phosphate binder prescription. Patient-level phosphate binder prescription was associated strongly at baseline with indicators of better nutrition, ie, higher values for serum creatinine, albumin, normalized protein catabolic rate, and body mass index and absence of cachectic appearance. Overall, patients prescribed phosphate binders had 25% lower mortality (HR, 0.75; 95% CI, 0.68-0.83) when adjusted for serum phosphorus level and other covariates; further adjustment for nutritional indicators attenuated this association (HR, 0.88; 95% CI, 0.80-0.97). However, this inverse association was observed for only patients with serum phosphorus levels ≥3.5 mg/dL. In the instrumental-variable analysis, case-mix-adjusted facility percentage of phosphate binder prescription (range, 23%-100%) was associated positively with better nutritional status and inversely with mortality (HR for 10% more phosphate binders, 0.93; 95% CI, 0.89-0.96). Further adjustment for nutritional indicators reduced this association to an HR of 0.95 (95% CI, 0.92-0.99). Results were based on phosphate binder prescription; phosphate binder and nutritional data were cross-sectional; dietary restriction was not assessed; observational design limits causal inference due to possible residual confounding. Longer survival and better nutritional status were observed for maintenance HD patients prescribed phosphate binders and in facilities with a greater percentage of phosphate binder prescription. Understanding the mechanisms for explaining this effect and ruling out possible residual confounding require additional research. Copyright © 2012 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Sports practice is related to parasympathetic activity in adolescents

PubMed Central

Cayres, Suziane Ungari; Vanderlei, Luiz Carlos Marques; Rodrigues, Aristides Machado; Coelho e Silva, Manuel João; Codogno, Jamile Sanches; Barbosa, Maurício Fregonesi; Fernandes, Rômulo Araújo

2015-01-01

OBJECTIVE: To analyze the relationship among sports practice, physical education class, habitual physical activity and cardiovascular risk in adolescents. METHODS: Cross-sectional study with 120 schoolchildren (mean: 11.7±0.7 years old), with no regular use of medicines. Sports practice and physical education classes were assessed through face-to-face interview, while habitual physical activity was assessed by pedometers. Bodyweight, height and height-cephalic trunk were used to estimate maturation. The following variables were measured: body fatness, blood pressure, resting heart rate, blood flow velocity, intima-media thickness (carotid and femoral) and heart rate variability (mean between consecutive heartbeats and statistical index in the time domain that show the autonomic parasympathetic nervous system activity root-mean by the square of differences between adjacent normal R-R intervals in a time interval). Statistical treatment used Spearman correlation adjusted by sex, ethnicity, age, body fatness and maturation. RESULTS: Independently of potential confounders, sports practice was positively related to autonomic parasympathetic nervous system activity (β=0.039 [0.01; 0.76]). On the other hand, the relationship between sport practice and mean between consecutive heartbeats (β=0,031 [-0.01; 0.07]) was significantly mediated by biological maturation. CONCLUSIONS: Sport practice was related to higher heart rate variability at rest. PMID:25887927

Smoking prevalence, determinants, knowledge, attitudes and habits among Buddhist monks in Lao PDR.

PubMed

Vanphanom, Sychareun; Phengsavanh, Alongkon; Hansana, Visanou; Menorath, Sing; Tomson, Tanja

2009-06-08

This cross-sectional study, the first of its kind, uses baseline data on smoking prevalence among Buddhist monks in Northern and Central provinces of Lao PDR. Between March and September 2006, 390 monks were interviewed, using questionnaires, to assess smoking prevalence including determinants, knowledge and attitudes. Data entry was performed with Epi-Info (version 6.04) and data analysis with SPSS version 11. Descriptive analysis was employed for all independent and dependent variables. Chi-square or Fisher's exact test were used for categorical variables to compare smoking status, knowledge, attitudes and province. Logistic regression was applied to identify determinants of smoking. Daily current smoking was 11.8%. Controlling for confounding variables, age at start of monkhood and the length of religious education were significant determinants of smoking. The majority of the monks 67.9% were in favor of the idea that offerings of cigarettes should be prohibited and that they should refuse the cigarettes offered to them (30.3%) but, in fact, 34.8% of the monks who were current smokers accepted cigarettes from the public. Some monks were smokers, whilst they, in fact, should be used as non-smoking role models. There was no anti-smoking policy in temples. This needs to be addressed when setting up smoke-free policies at temples.

Permethrin Exposure Dosimetry: Biomarkers and Modifiable Factors

DTIC Science & Technology

2017-08-01

metabolite; (F = 16.16, p < 0.0001). This association holds after controlling for known confounders including sex , age, time that uniform was worn...and metabolite concentrations were examined via linear mixed modeling. All models were adjusted for creatinine, age, sex , days in BCT, number of

Exposure to traffic-related air pollution and risk of development of childhood asthma: A systematic review and meta-analysis.

PubMed

Khreis, Haneen; Kelly, Charlotte; Tate, James; Parslow, Roger; Lucas, Karen; Nieuwenhuijsen, Mark

2017-03-01

The question of whether children's exposure to traffic-related air pollution (TRAP) contributes to their development of asthma is unresolved. We conducted a systematic review and performed meta-analyses to analyze the association between TRAP and asthma development in childhood. We systematically reviewed epidemiological studies published until 8 September 2016 and available in the Embase, Ovid MEDLINE (R), and Transport databases. We included studies that examined the association between children's exposure to TRAP metrics and their risk of 'asthma' incidence or lifetime prevalence, from birth to age 18years old. We extracted key characteristics of each included study using a predefined data items template and these were tabulated. We used the Critical Appraisal Skills Programme checklists to assess the validity of each included study. Where four or more independent risk estimates were available for a continuous pollutant exposure, we conducted overall and age-specific meta-analyses, and four sensitivity analyses for each summary meta-analytic exposure-outcome association. Forty-one studies met our eligibility criteria. There was notable variability in asthma definitions, TRAP exposure assessment methods and confounder adjustment. The overall random-effects risk estimates (95% CI) were 1.08 (1.03, 1.14) per 0.5×10 -5 m -1 black carbon (BC), 1.05 (1.02, 1.07) per 4μg/m 3 nitrogen dioxide (NO 2 ), 1.48 (0.89, 2.45) per 30μg/m 3 nitrogen oxides (NO x ), 1.03 (1.01, 1.05) per 1μg/m 3 Particulate Matter <2.5μm in diameter (PM 2.5 ), and 1.05 (1.02, 1.08) per 2μg/m 3 Particulate Matter <10μm in diameter (PM 10 ). Sensitivity analyses supported these findings. Across the main analysis and age-specific analysis, the least heterogeneity was seen for the BC estimates, some heterogeneity for the PM 2.5 and PM 10 estimates and the most heterogeneity for the NO 2 and NO x estimates. The overall risk estimates from the meta-analyses showed statistically significant associations for BC, NO 2 , PM 2.5 , PM 10 exposures and risk of asthma development. Our findings support the hypothesis that childhood exposure to TRAP contributes to their development of asthma. Future meta-analyses would benefit from greater standardization of study methods including exposure assessment harmonization, outcome harmonization, confounders' harmonization and the inclusion of all important confounders in individual studies. PROSPERO 2014: CRD42014015448. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mothers' spanking of 3-year-old children and subsequent risk of children's aggressive behavior.

PubMed

Taylor, Catherine A; Manganello, Jennifer A; Lee, Shawna J; Rice, Janet C

2010-05-01

The goal was to examine the association between the use of corporal punishment (CP) against 3-year-old children and subsequent aggressive behavior among those children. Respondents (N = 2461) participated in the Fragile Families and Child Well-being Study (1998-2005), a population-based, birth cohort study of children born in 20 large US cities. Maternal reports of CP, children's aggressive behaviors at 3 and 5 years of age, and a host of key demographic features and potential confounding factors, including maternal child physical maltreatment, psychological maltreatment, and neglect, intimate partner aggression victimization, stress, depression, substance use, and consideration of abortion, were assessed. Frequent use of CP (ie, mother's use of spanking more than twice in the previous month) when the child was 3 years of age was associated with increased risk for higher levels of child aggression when the child was 5 years of age (adjusted odds ratio: 1.49 [95% confidence interval: 1.2-1.8]; P < .0001), even with controlling for the child's level of aggression at age 3 and the aforementioned potential confounding factors and key demographic features. Despite American Academy of Pediatrics recommendations to the contrary, most parents in the United States approve of and have used CP as a form of child discipline. The current findings suggest that even minor forms of CP, such as spanking, increase risk for increased child aggressive behavior. Importantly, these findings cannot be attributed to possible confounding effects of a host of other maternal parenting risk factors.

Food swamps and food deserts in Baltimore City, MD, USA: associations with dietary behaviours among urban adolescent girls.

PubMed

Hager, Erin R; Cockerham, Alexandra; O'Reilly, Nicole; Harrington, Donna; Harding, James; Hurley, Kristen M; Black, Maureen M

2017-10-01

To determine whether living in a food swamp (≥4 corner stores within 0·40 km (0·25 miles) of home) or a food desert (generally, no supermarket or access to healthy foods) is associated with consumption of snacks/desserts or fruits/vegetables, and if neighbourhood-level socio-economic status (SES) confounds relationships. Cross-sectional. Assessments included diet (Youth/Adolescent FFQ, skewed dietary variables normalized) and measured height/weight (BMI-for-age percentiles/Z-scores calculated). A geographic information system geocoded home addresses and mapped food deserts/food swamps. Associations examined using multiple linear regression (MLR) models adjusting for age and BMI-for-age Z-score. Baltimore City, MD, USA. Early adolescent girls (6th/7th grade, n 634; mean age 12·1 years; 90·7 % African American; 52·4 % overweight/obese), recruited from twenty-two urban, low-income schools. Girls' consumption of fruit, vegetables and snacks/desserts: 1·2, 1·7 and 3·4 servings/d, respectively. Girls' food environment: 10·4 % food desert only, 19·1 % food swamp only, 16·1 % both food desert/swamp and 54·4 % neither food desert/swamp. Average median neighbourhood-level household income: $US 35 298. In MLR models, girls living in both food deserts/swamps consumed additional servings of snacks/desserts v. girls living in neither (β=0·13, P=0·029; 3·8 v. 3·2 servings/d). Specifically, girls living in food swamps consumed more snacks/desserts than girls who did not (β=0·16, P=0·003; 3·7 v. 3·1 servings/d), with no confounding effect of neighbourhood-level SES. No associations were identified with food deserts or consumption of fruits/vegetables. Early adolescent girls living in food swamps consumed more snacks/desserts than girls not living in food swamps. Dietary interventions should consider the built environment/food access when addressing adolescent dietary behaviours.

Cross-border policy effects on alcohol outcomes: drinking without thinking on the u.s.-Mexico border?

PubMed

Mills, Britain A; Caetano, Raul; Vaeth, Patrice

2014-11-01

Rates of alcohol-related outcomes are sensitive to policy differences in politically distinct, adjacent territories. Factors that shape these cross-border effects, particularly when the policy differences are longstanding, remain poorly understood. We compared the ability of 2 classes of variables with theoretical relevance to the U.S.-Mexico border context-bar attendance and alcohol-related social-cognitive variables-to explain elevated drinking on the U.S. side of the border relative to other areas of the United States. Data were collected from multistage cluster samples of adult Mexican Americans on and off the U.S.-Mexico border (current drinker N = 1,351). Structural equation models were used to test drinking context (frequency of bar attendance) and 6 different social-cognitive variables (including alcohol-related attitudes, norms, motives, and beliefs) as mediators of border effects on a composite drinking index. The border effect on drinking varied by age (with younger adults showing a stronger effect), consistent with previous findings and known risk factors in the region. Contrary to theoretical expectations, 6 different social-cognitive variables-despite relating strongly with drinking-were comparable in border and nonborder areas (within and across age) and played no role in elevated drinking on the border. Conversely, elevated drinking among border youth was mediated by bar attendance. This mediated moderation effect held after adjusting for potential sociodemographic and neighborhood-level confounders. Increased drinking among U.S.-Mexico border youth is explained by patterns of bar attendance, but not by more permissive alcohol-related social-cognitive variables in border areas: Border youth attend bars and drink more than their nonborder counterparts, despite having comparable alcohol-related beliefs, attitudes, norms, and motives for use. Alcohol's heightened availability and visibility on both sides of the border may create opportunities for border youth to drink that otherwise would not be considered. Copyright © 2014 by the Research Society on Alcoholism.

COMPOSITE SAMPLING FOR SOIL VOC ANALYSIS

EPA Science Inventory

Data published by numerous researchers over the last decade demonstrate that there is a high degree of spatial variability in the measurement of volatile organic compounds (VOCs) in soil at contaminated waste sites. This phenomenon is confounded by the use of a small sample aliqu...

Prevalence and determinant factors of exclusive breastfeeding practices among mothers in Enderta woreda, Tigray, North Ethiopia: a cross-sectional study.

PubMed

Teka, Bahre; Assefa, Huruy; Haileslassie, Kiday

2015-01-01

In Ethiopia national breastfeeding practice is poor because of traditional and cultural beliefs, low educational levels, heavy workload of mothers, poor sanitary conditions, type of assistance at delivery, duration of stay at home, ethnicity, poor maternal knowledge, age, parity, antenatal service utilization and place of delivery. This study is aimed to assess the prevalence and determinants of exclusive breastfeeding practice in mothers in Enderta woreda (district), Ethiopia. A community based cross-sectional study with multistage sampling method was used to select 541 mothers with children less than 24 months of age in Enderta woreda. Data was collected by administered structured questionnaire. Bivariate and Multivariable logistic regression was used to check the associations and controlling confounding variables. A total of 530 mothers were included with a response rate 98%. The mean (± SD) age of the mothers was 26.9 (± 5.98) years. Majority of the mothers (70.2%) were practiced exclusive breastfeeding. Age of the mother (AOR 0.12; 95% CI: 0.02, 0.97), age of the child (AOR 0.52 95% CI: 0.27, 0.99) and postnatal care (AOR; 2.68; 95% CI: 1.44, 4.98) were found statistically significant with exclusive breastfeeding. The prevalence rate of exclusive breastfeeding was high in Enderta woreda. The age of the mother, age of the child and receiving postnatal care were the determinant factors for exclusive breastfeeding in the study area.