Persistent smoking as a predictor of disability pension due to musculoskeletal diagnoses: a 23 year prospective study of Finnish twins.

PubMed

Ropponen, Annina; Korhonen, Tellervo; Svedberg, Pia; Koskenvuo, Markku; Silventoinen, Karri; Kaprio, Jaakko

2013-12-01

To investigate whether stability or changes in smoking predict disability pension (DP) due to low back diagnoses (LBD) and musculoskeletal diagnoses (MSD) after taking familial confounding into account using a co-twin design. Longitudinal smoking patterns and multiple covariates in a population-based cohort of 17,451 Finnish twins (6959 complete pairs) born before 1958 were surveyed through questionnaires in 1975 and 1981. The outcome data were collected from the national pension registers until the end of 2004. Cox proportional hazards regression models were used for statistical analyses. Disability pension due to low back diagnoses was granted to 408 individuals and disability pension due to musculoskeletal diagnoses to 1177 individuals during the follow-up of 23 years. Being a persistent smoker (current smoker both 1975 and 1981) predicted a significantly increased risk for disability pension (hazard ratio 1.69, 95% confidence interval 1.46, 1.97) compared to those individuals who had never smoked. The association remained when several confounding factors, including familial factors, were taken into account. Persistent smoking predicts early disability pension due to musculoskeletal diagnoses and low back diagnoses independently from numerous confounding factors, including familial effects shared by the co-twins. © 2013.

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.

Beyond greening and browning: the need for an integrated understanding of Arctic change

NASA Astrophysics Data System (ADS)

Gamon, J. A.; Huemmrich, K. F.; Hmimina, G.; Yu, R.

2017-12-01

Satellite records and field observations povide contradictory evidence for "greening" or "browning" of Arctic tundra. Large-scale observations of apparent greening have been based on satellite vegetation indices (e.g NDVI). However, a clear interpretation of these trends are confounded by changing snow cover and surface hydrology, both of which influence NDVI and are known to be changing independently of any direct vegetation response. Field studies have demonstrated greening in some areas, but not others, and have also documented changing permafrost depth, surface hydrology and snow cover. Together, these confounding factors can explain some of the contradictory evidence based regarding greening and browning. Given the multiple influences on Arctic NDVI, simple conclusions regarding greening and browning from satellite data alone can be incorrect; when these confounding factors are taken into account, some areas that show apparent greening in the satellite record appear to be undergoing productivity declines due to surface drying. These contradictory interpretations have profound implications for our understanding of changing surface energy balance, biogeochemistry, and surface-atmosphere feedbacks. To better address Arctic ecosystem responses to a changing climate, an integrated, multi-scale, multivariate approach that considers hydrology, permafrost, snow cover and vegetation is needed.

Confounding factors and genetic polymorphism in the evaluation of individual steroid profiling

PubMed Central

Kuuranne, Tiia; Saugy, Martial; Baume, Norbert

2014-01-01

In the fight against doping, steroid profiling is a powerful tool to detect drug misuse with endogenous anabolic androgenic steroids. To establish sensitive and reliable models, the factors influencing profiling should be recognised. We performed an extensive literature review of the multiple factors that could influence the quantitative levels and ratios of endogenous steroids in urine matrix. For a comprehensive and scientific evaluation of the urinary steroid profile, it is necessary to define the target analytes as well as testosterone metabolism. The two main confounding factors, that is, endogenous and exogenous factors, are detailed to show the complex process of quantifying the steroid profile within WADA-accredited laboratories. Technical aspects are also discussed as they could have a significant impact on the steroid profile, and thus the steroid module of the athlete biological passport (ABP). The different factors impacting the major components of the steroid profile must be understood to ensure scientifically sound interpretation through the Bayesian model of the ABP. Not only should the statistical data be considered but also the experts in the field must be consulted for successful implementation of the steroidal module. PMID:24764553

PERMANOVA-S: association test for microbial community composition that accommodates confounders and multiple distances.

PubMed

Tang, Zheng-Zheng; Chen, Guanhua; Alekseyenko, Alexander V

2016-09-01

Recent advances in sequencing technology have made it possible to obtain high-throughput data on the composition of microbial communities and to study the effects of dysbiosis on the human host. Analysis of pairwise intersample distances quantifies the association between the microbiome diversity and covariates of interest (e.g. environmental factors, clinical outcomes, treatment groups). In the design of these analyses, multiple choices for distance metrics are available. Most distance-based methods, however, use a single distance and are underpowered if the distance is poorly chosen. In addition, distance-based tests cannot flexibly handle confounding variables, which can result in excessive false-positive findings. We derive presence-weighted UniFrac to complement the existing UniFrac distances for more powerful detection of the variation in species richness. We develop PERMANOVA-S, a new distance-based method that tests the association of microbiome composition with any covariates of interest. PERMANOVA-S improves the commonly-used Permutation Multivariate Analysis of Variance (PERMANOVA) test by allowing flexible confounder adjustments and ensembling multiple distances. We conducted extensive simulation studies to evaluate the performance of different distances under various patterns of association. Our simulation studies demonstrate that the power of the test relies on how well the selected distance captures the nature of the association. The PERMANOVA-S unified test combines multiple distances and achieves good power regardless of the patterns of the underlying association. We demonstrate the usefulness of our approach by reanalyzing several real microbiome datasets. miProfile software is freely available at https://medschool.vanderbilt.edu/tang-lab/software/miProfile z.tang@vanderbilt.edu or g.chen@vanderbilt.edu Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

PERMANOVA-S: association test for microbial community composition that accommodates confounders and multiple distances

PubMed Central

Tang, Zheng-Zheng; Chen, Guanhua; Alekseyenko, Alexander V.

2016-01-01

Motivation: Recent advances in sequencing technology have made it possible to obtain high-throughput data on the composition of microbial communities and to study the effects of dysbiosis on the human host. Analysis of pairwise intersample distances quantifies the association between the microbiome diversity and covariates of interest (e.g. environmental factors, clinical outcomes, treatment groups). In the design of these analyses, multiple choices for distance metrics are available. Most distance-based methods, however, use a single distance and are underpowered if the distance is poorly chosen. In addition, distance-based tests cannot flexibly handle confounding variables, which can result in excessive false-positive findings. Results: We derive presence-weighted UniFrac to complement the existing UniFrac distances for more powerful detection of the variation in species richness. We develop PERMANOVA-S, a new distance-based method that tests the association of microbiome composition with any covariates of interest. PERMANOVA-S improves the commonly-used Permutation Multivariate Analysis of Variance (PERMANOVA) test by allowing flexible confounder adjustments and ensembling multiple distances. We conducted extensive simulation studies to evaluate the performance of different distances under various patterns of association. Our simulation studies demonstrate that the power of the test relies on how well the selected distance captures the nature of the association. The PERMANOVA-S unified test combines multiple distances and achieves good power regardless of the patterns of the underlying association. We demonstrate the usefulness of our approach by reanalyzing several real microbiome datasets. Availability and Implementation: miProfile software is freely available at https://medschool.vanderbilt.edu/tang-lab/software/miProfile. Contact: z.tang@vanderbilt.edu or g.chen@vanderbilt.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27197815

Confounding adjustment in comparative effectiveness research conducted within distributed research networks.

PubMed

Toh, Sengwee; Gagne, Joshua J; Rassen, Jeremy A; Fireman, Bruce H; Kulldorff, Martin; Brown, Jeffrey S

2013-08-01

A distributed research network (DRN) of electronic health care databases, in which data reside behind the firewall of each data partner, can support a wide range of comparative effectiveness research (CER) activities. An essential component of a fully functional DRN is the capability to perform robust statistical analyses to produce valid, actionable evidence without compromising patient privacy, data security, or proprietary interests. We describe the strengths and limitations of different confounding adjustment approaches that can be considered in observational CER studies conducted within DRNs, and the theoretical and practical issues to consider when selecting among them in various study settings. Several methods can be used to adjust for multiple confounders simultaneously, either as individual covariates or as confounder summary scores (eg, propensity scores and disease risk scores), including: (1) centralized analysis of patient-level data, (2) case-centered logistic regression of risk set data, (3) stratified or matched analysis of aggregated data, (4) distributed regression analysis, and (5) meta-analysis of site-specific effect estimates. These methods require different granularities of information be shared across sites and afford investigators different levels of analytic flexibility. DRNs are growing in use and sharing of highly detailed patient-level information is not always feasible in DRNs. Methods that incorporate confounder summary scores allow investigators to adjust for a large number of confounding factors without the need to transfer potentially identifiable information in DRNs. They have the potential to let investigators perform many analyses traditionally conducted through a centralized dataset with detailed patient-level information.

[Adoption of new technologies by health services: the challenge of analyzing relevant factors].

PubMed

Trindade, Evelinda

2008-05-01

The exponential increase in the incorporation of health technologies has been considered a key factor in increased expenditures by the health sector. Such decisions involve multiple levels and stakeholders. Decentralization has multiplied the decision-making levels, with numerous difficult choices and limited resources. The interrelationship between stakeholders is complex, in creative systems with multiple determinants and confounders. The current review discusses the interaction between the factors influencing the decisions to incorporate technologies by health services, and proposes a structure for their analysis. The application and intensity of these factors in decision-making and the incorporation of products and programs by health services shapes the installed capacity of local and regional networks and modifies the health system. Empirical observation of decision-making and technology incorporation in Brazilian health services poses an important challenge. The structured recognition and measurement of these variables can assist proactive planning of health services.

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.

Re-examining the link between prenatal maternal anxiety and child emotional difficulties, using a sibling design.

PubMed

Bekkhus, Mona; Lee, Yunsung; Nordhagen, Rannveig; Magnus, Per; Samuelsen, Sven O; Borge, Anne I H

2018-02-01

Prenatal exposure to maternal anxiety has been associated with child emotional difficulties in a number of epidemiological studies. One key concern, however, is that this link is vulnerable to confounding by pleiotropic genes or environmental family factors. Data on 82 383 mothers and children from the population-based Mother and Child Cohort Study and data on 21 980 siblings were used in this study. Mothers filled out questionnaires for each unique pregnancy, for infant difficulties at 6 months and for emotional difficulties at 36 months. The link between prenatal maternal anxiety and child difficulties were examined using logistic regression analyses and multiple linear regression analyses for the full study sample and the sibling sample. In the conventional full-cohort analyses, prenatal exposure to maternal anxiety was associated with child difficulties at both 6 months [odds ratio (OR) = 2.1 (1.94-2.27)] and 36 months [OR = 2.72 (2.47-2.99)]. The findings were essentially the same whether we examined difficulties at 6 months or at 36 months. However, these associations were no longer present once we controlled for potential social and genetic confounders in the sibling comparison analyses, either at 6 months [OR = 1.32 (0.91-1.90)] or at 36 months [OR = 1.28 (0.63-2.60)]. Findings from multiple regression analyses with continuous measures were essentially the same. Our finding lends little support for there being an independent prenatal effect on child emotional difficulties; rather, our findings suggest that the link between prenatal maternal anxiety and child difficulties could be confounded by pleiotropic genes or environmental family factors. © The Author 2017; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association

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.

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

Urinary excretion of mutagens in coke oven workers.

PubMed

Clonfero, E; Granella, M; Marchioro, M; Barra, E L; Nardini, B; Ferri, G; Foà, V

1995-03-01

The influence of occupational exposure to polycyclic aromatic hydrocarbons (PAHs) on urinary mutagenic activity was assessed in 75 coke oven workers, using a highly sensitive bacterial mutagen technique (extraction with C18 resin and liquid micro-preincubation test on strain TA98 of Salmonella typhimurium in the presence of metabolizing and deconjugating enzymes). Exposure to PAHs was assessed according to the urinary excretion of 1-pyrenol; the main confounding factors were checked by the number of cigarettes smoked per day and the levels of nicotine and its metabolites in urine, or by ascertaining whether recommended dietary restrictions had been followed. Of the 20 urine samples which turned out to be positive (producing at least double the number of spontaneous revertants), 19 (95%) belonged to smokers. Only one non-smoker had obvious urinary mutagenic activity, and was highly exposed occupationally to PAHs (urinary 1-pyrenol of 3.930 mumol/mol of creatinine). Of the five urine samples from subjects who had not followed the recommended diet, two (40%) were clearly mutagenic. Multiple regression analysis (n = 67) showed that the presence of samples positive for urinary mutagenic activity depended only on smoking habits, if this confounding factor was assessed according to the number of cigarettes smoked per day, while the significant influence of exposure to PAH could be shown when the confounding factor was objectively estimated according to the urinary levels of nicotine and its metabolites. Assessment of the mutagenic potency of urinary extracts (net revertants/mmol creatinine) confirmed the strong influence of smoking habits on urinary mutagenic activity (all smokers 2156 +/- 2691 versus non-smokers 939 +/- 947 net revertants/mmol creatinine; Mann-Whitney test: P < 0.01). In smokers highly exposed to PAHs, greater excretion of mutagens with respect to low-exposure smokers was revealed (3548 +/- 4009 versus 1552 +/- 1227 net revertants/mmol creatinine; Mann-Whitney test: P < 0.01). Multiple regression analysis showed that the mutagenic potency of urinary extracts of coke oven workers depended on exposure to PAHs, tobacco smoking habits, and consumption of fried, grilled or barbecued meat. Increased urinary mutagenic activity strengthens epidemiological evidence of the increased risk of renal and urinary tract tumours in these workers. The presence of mutagenic metabolites in urine as a result of occupational exposure to PAH may be demonstrated only by using highly sensitive techniques for assessing urinary mutagenic activity in studies which include careful checking of the main confounding factors.

Association between education and future leisure-time physical inactivity: a study of Finnish twins over a 35-year follow-up.

PubMed

Piirtola, Maarit; Kaprio, Jaakko; Kujala, Urho M; Heikkilä, Kauko; Koskenvuo, Markku; Svedberg, Pia; Silventoinen, Karri; Ropponen, Annina

2016-08-04

Education is associated with health related lifestyle choices including leisure-time physical inactivity. However, the longitudinal associations between education and inactivity merit further studies. We investigated the association between education and leisure-time physical inactivity over a 35-year follow-up with four time points controlling for multiple covariates including familial confounding. This study of the population-based Finnish Twin Cohort consisted of 5254 twin individuals born in 1945-1957 (59 % women), of which 1604 were complete same-sexed twin pairs. Data on leisure-time physical activity and multiple covariates was available from four surveys conducted in 1975, 1981, 1990 and 2011 (response rates 72 to 89 %). The association between years of education and leisure-time physical inactivity (<1.5 metabolic equivalent hours/day) was first analysed for each survey. Then, the role of education was investigated for 15-year and 35-year inactivity periods in the longitudinal analyses. The co-twin control design was used to analyse the potential familial confounding of the effects. All analyses were conducted with and without multiple covariates. Odds Ratios (OR) with 95 % Confidence Intervals (CI) were calculated using logistic and conditional (fixed-effects) regression models. Each additional year of education was associated with less inactivity (OR 0.94 to 0.95, 95 % CI 0.92, 0.99) in the cross-sectional age- and sex-adjusted analyses. The associations of education with inactivity in the 15- and 35-year follow-ups showed a similar trend: OR 0.97 (95 % CI 0.93, 1.00) and OR 0.94 (95 % CI 0.91, 0.98), respectively. In all co-twin control analyses, each year of higher education was associated with a reduced likelihood of inactivity suggesting direct effect (i.e. independent from familial confounding) of education on inactivity. However, the point estimates were lower than in the individual-level analyses. Adjustment for multiple covariates did not change these associations. Higher education is associated with lower odds of leisure-time physical inactivity during the three-decade follow-up. The association was found after adjusting for several confounders, including familial factors. Hence, the results point to the conclusion that education has an independent role in the development of long-term physical inactivity and tailored efforts to promote physical activity among lower educated people would be needed throughout adulthood.

Low socioeconomic status is a risk factor for preeclampsia: the Generation R Study.

PubMed

Silva, Lindsay M; Coolman, Marianne; Steegers, Eric Ap; Jaddoe, Vincent Wv; Moll, Henriëtte A; Hofman, Albert; Mackenbach, Johan P; Raat, Hein

2008-06-01

To examine whether maternal socioeconomic status, as indicated by maternal educational level, is associated with preeclampsia, and if so, to what extent known risk factors for preeclampsia mediate the effect of educational level. In the Generation R Study, a population-based cohort study, we examined data of 3547 pregnant women. Odds ratios of preeclampsia for low, mid-low and mid-high educational level compared with high educational level were calculated after adjustment for confounders and additional adjustment for a selection of potential mediators (family history, material factors, psychosocial factors, substance use, working conditions, preexisting medical conditions, maternal anthropometrics and blood pressure at enrollment) that individually caused more than 10% change in the odds ratio for low education. Adjusted for the confounding effects of age, gravidity and multiple pregnancy, women with low educational level were more likely to develop preeclampsia (odds ratio 5.12; 95% confidence interval: 2.20, 11.93) than women with high educational level. After additional adjustment for financial difficulties, smoking in pregnancy, working conditions, body mass index and blood pressure at enrollment, the odds ratio was 4.91 (95% confidence interval: 1.93, 12.52). Low maternal socioeconomic status is a strong risk factor for preeclampsia. Only a small part of this association can be explained by the mediating effects of established risk factors for preeclampsia. Further research is needed to disentangle the pathway from low socioeconomic status to preeclampsia.

Synergistic and Non-synergistic Associations for Cigarette Smoking and Non-tobacco Risk Factors for Cardiovascular Disease Incidence in the Atherosclerosis Risk In Communities (ARIC) Study.

PubMed

Lubin, Jay H; Couper, David; Lutsey, Pamela L; Yatsuya, Hiroshi

2017-07-01

Cigarette smoking, various metabolic and lipid-related factors and hypertension are well-recognized cardiovascular disease (CVD) risk factors. Since smoking affects many of these factors, use of a single imprecise smoking metric, for example, ever or never smoked, may allow residual confounding and explain inconsistencies in current assessments of interactions. Using a comprehensive model in pack-years and cigarettes/day for the complex smoking-related relative risk (RR) of CVD to reduce residual confounding, we evaluated interactions with non-tobacco risk factors, including additive (non-synergistic) and multiplicative (synergistic) forms. Data were from the prospective Atherosclerosis Risk in Communities (ARIC) Study from four areas of the United States recruited in 1987-1989 with follow-up through 2008. Analyses included 14 127 participants, 207 693 person-years and 2857 CVD events. Analyses revealed distinct interactions with smoking: including statistical consistency with additive (body mass index [BMI], waist to hip ratio [WHR], diabetes mellitus [DM], glucose, insulin, high density lipoproteins [HDL] and HDL(2)); and multiplicative (hypertension, total cholesterol [TC], low density lipoproteins [LDLs], apolipoprotein B [apoB], TC to HDL ratio and HDL(3)) associations, as well as indeterminate (apolipoprotein A-I [apoA-I] and triglycerides) associations. The forms of the interactions were revealing but require confirmation. Improved understanding of joint associations may help clarify the public health burden of smoking for CVD, links between etiologic factors and biological mechanisms, and the consequences of joint exposures, whereby synergistic associations highlight joint effects and non-synergistic associations suggest distinct contributions. Joint associations for cigarette smoking and non-tobacco risk factors were distinct, revealing synergistic/multiplicative (hypertension, TC, LDL, apoB, TC/HDL, HDL(3)), non-synergistic/additive (BMI, WHR, DM, glucose, insulin, HDL, HDL(2)) and indeterminate (apoA-I and TRIG) associations. If confirmed, these results may help better define the public health burden of smoking on CVD risk and identify links between etiologic factors and biologic mechanisms, where synergistic associations highlight joint impacts and non-synergistic associations suggest distinct contributions from each factor. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

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

When can the cause of a population decline be determined?

PubMed

Hefley, Trevor J; Hooten, Mevin B; Drake, John M; Russell, Robin E; Walsh, Daniel P

2016-11-01

Inferring the factors responsible for declines in abundance is a prerequisite to preventing the extinction of wild populations. Many of the policies and programmes intended to prevent extinctions operate on the assumption that the factors driving the decline of a population can be determined. Exogenous factors that cause declines in abundance can be statistically confounded with endogenous factors such as density dependence. To demonstrate the potential for confounding, we used an experiment where replicated populations were driven to extinction by gradually manipulating habitat quality. In many of the replicated populations, habitat quality and density dependence were confounded, which obscured causal inference. Our results show that confounding is likely to occur when the exogenous factors that are driving the decline change gradually over time. Our study has direct implications for wild populations, because many factors that could drive a population to extinction change gradually through time. © 2016 John Wiley & Sons Ltd/CNRS.

When can the cause of a population decline be determined?

USGS Publications Warehouse

Hefley, Trevor J.; Hooten, Mevin B.; Drake, John M.; Russell, Robin E.; Walsh, Daniel P.

2016-01-01

Inferring the factors responsible for declines in abundance is a prerequisite to preventing the extinction of wild populations. Many of the policies and programmes intended to prevent extinctions operate on the assumption that the factors driving the decline of a population can be determined. Exogenous factors that cause declines in abundance can be statistically confounded with endogenous factors such as density dependence. To demonstrate the potential for confounding, we used an experiment where replicated populations were driven to extinction by gradually manipulating habitat quality. In many of the replicated populations, habitat quality and density dependence were confounded, which obscured causal inference. Our results show that confounding is likely to occur when the exogenous factors that are driving the decline change gradually over time. Our study has direct implications for wild populations, because many factors that could drive a population to extinction change gradually through time.

A framework for a critical assessment of the quality of epidemiological studies of driver health and accident risk.

PubMed

Elvik, Rune

2011-11-01

A large number of studies have tried to assess how various aspects of driver health influence driver involvement in accidents. The objective of this paper is to provide a framework for a critical assessment of the quality these studies from a methodological point of view. Examples are given of how various sources of bias and confounding can produce study findings that are highly misleading. Ten potential sources of error and bias in epidemiological studies of the contribution of driver health impairments to road accidents are discussed: (1) Poor description of the medical conditions whose effects are studied (measurement error). (2) Inadequate control for the effects of exposure on accident rate. (3) Sampling endogeneity with respect to assessment for fitness to drive (outcome-based sampling; self-selection bias). (4) Combined exposure to several risk factors. (5) Poor control for potentially confounding factors. (6) Failure to specify potentially moderating factors (interaction effects). (7) Failure to consider a severity gradient with respect to the effect of health impairments. (8) Failure to specify the compliance of drivers with medical treatments or treatment effectiveness. (9) No data on the population prevalence of various health conditions. (10) The use of multiple study approaches and methods making the comparison and synthesis of findings difficult. Examples are given of how all these items may influence the findings of a single study or make synthesising findings from multiple studies difficult. A checklist for assessing study quality is provided. Copyright © 2011 Elsevier Ltd. All rights reserved.

Association between prolonged breast-feeding and early childhood caries: a hierarchical approach.

PubMed

Nunes, Ana Margarida Melo; Alves, Claudia Maria Coelho; Borba de Araújo, Fernando; Ortiz, Tânia Mara Lopes; Ribeiro, Marizélia Rodrigues Costa; Silva, Antônio Augusto Moura da; Ribeiro, Cecília Claudia Costa

2012-12-01

This study was conducted to investigate the association between prolonged breastfeeding and early childhood caries(ECC) with adjustment for important confounders, using hieraschical approach. This retrospective cohort study involved 260 low-income children (18-42 months). The number of decayed teeth was used as a measure of caries. Following a theoretical framework, the hierarchical model was built in a forward fashion, by adding the following levels in succession: level 1: age; level 2: social variables; level 3: health variables; level 4: behavioral variables; level 5: oral hygiene-related variables; level 6: oral hygiene quality measured by visible plaque; and level 7: contamination by mutans streptococci. Sequential forward multiple Poisson regression analysis was employed. Breast-feeding was not a risk factor for ECC after adjustment for some confounders (incidence density ratio, 1.15; 95% confidence interval, 0.84-1.59, P = 0.363). Prolonged breast-feeding was not a risk factor for ECC while age, high sucrose comption between main meals and the quality of oral higiene were associated with disease in children. © 2012 John Wiley & Sons A/S.

Correction of confounding bias in non-randomized studies by appropriate weighting.

PubMed

Schmoor, Claudia; Gall, Christine; Stampf, Susanne; Graf, Erika

2011-03-01

In non-randomized studies, the assessment of a causal effect of treatment or exposure on outcome is hampered by possible confounding. Applying multiple regression models including the effects of treatment and covariates on outcome is the well-known classical approach to adjust for confounding. In recent years other approaches have been promoted. One of them is based on the propensity score and considers the effect of possible confounders on treatment as a relevant criterion for adjustment. Another proposal is based on using an instrumental variable. Here inference relies on a factor, the instrument, which affects treatment but is thought to be otherwise unrelated to outcome, so that it mimics randomization. Each of these approaches can basically be interpreted as a simple reweighting scheme, designed to address confounding. The procedures will be compared with respect to their fundamental properties, namely, which bias they aim to eliminate, which effect they aim to estimate, and which parameter is modelled. We will expand our overview of methods for analysis of non-randomized studies to methods for analysis of randomized controlled trials and show that analyses of both study types may target different effects and different parameters. The considerations will be illustrated using a breast cancer study with a so-called Comprehensive Cohort Study design, including a randomized controlled trial and a non-randomized study in the same patient population as sub-cohorts. This design offers ideal opportunities to discuss and illustrate the properties of the different approaches. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Perceived school safety is strongly associated with adolescent mental health problems.

PubMed

Nijs, Miesje M; Bun, Clothilde J E; Tempelaar, Wanda M; de Wit, Niek J; Burger, Huibert; Plevier, Carolien M; Boks, Marco P M

2014-02-01

School environment is an important determinant of psychosocial function and may also be related to mental health. We therefore investigated whether perceived school safety, a simple measure of this environment, is related to mental health problems. In a population-based sample of 11,130 secondary school students, we analysed the relationship of perceived school safety with mental health problems using multiple logistic regression analyses to adjust for potential confounders. Mental health problems were defined using the clinical cut-off of the self-reported Strengths and Difficulties Questionnaire. School safety showed an exposure-response relationship with mental health problems after adjustment for confounders. Odds ratios increased from 2.48 ("sometimes unsafe") to 8.05 ("very often unsafe"). The association was strongest in girls and young and middle-aged adolescents. Irrespective of the causal background of this association, school safety deserves attention either as a risk factor or as an indicator of mental health problems.

Associations between Distal Upper Extremity Job Physical Factors and Psychosocial Measures in a Pooled Study

PubMed Central

2015-01-01

Introduction. There is an increasing body of literature relating musculoskeletal diseases to both job physical exposures and psychosocial outcomes. Relationships between job physical exposure measures and psychosocial factors have not been well examined or quantified. These exploratory analyses evaluate relationships between quantified exposures and psychosocial outcomes. Methods. Individualized quantification of duration, repetition, and force and composite scores of the Strain Index (SI) and the Threshold Limit Value for Hand Activity Level (TLV for HAL) were compared to 10 psychosocial measures. Relationships and predicted probabilities were assessed using ordered logistic regression. Analyses were adjusted for age, BMI, and gender. Results and Discussion. Among 1834 study participants there were multiple statistically significant relationships. In general, as duration, repetition, and force increased, psychosocial factors worsened. However, general health and mental exhaustion improved with increasing job exposures. Depression was most strongly associated with increased repetition, while physical exhaustion was most strongly associated with increased force. SI and TLV for HAL were significantly related to multiple psychosocial factors. These relationships persisted after adjustment for strong confounders. Conclusion. This study quantified multiple associations between job physical exposures and occupational and nonoccupational psychosocial factors. Further research is needed to quantify the impacts on occupational health outcomes. PMID:26557686

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.

Integrative assessment of multiple pesticides as risk factors for non-Hodgkin's lymphoma among men

PubMed Central

De Roos, A J; Zahm, S; Cantor, K; Weisenburger, D; Holmes, F; Burmeister, L; Blair, A

2003-01-01

Methods: During the 1980s, the National Cancer Institute conducted three case-control studies of NHL in the midwestern United States. These pooled data were used to examine pesticide exposures in farming as risk factors for NHL in men. The large sample size (n = 3417) allowed analysis of 47 pesticides simultaneously, controlling for potential confounding by other pesticides in the model, and adjusting the estimates based on a prespecified variance to make them more stable. Results: Reported use of several individual pesticides was associated with increased NHL incidence, including organophosphate insecticides coumaphos, diazinon, and fonofos, insecticides chlordane, dieldrin, and copper acetoarsenite, and herbicides atrazine, glyphosate, and sodium chlorate. A subanalysis of these "potentially carcinogenic" pesticides suggested a positive trend of risk with exposure to increasing numbers. Conclusion: Consideration of multiple exposures is important in accurately estimating specific effects and in evaluating realistic exposure scenarios. PMID:12937207

Effect of antenatal corticosteroids on fetal growth and gestational age at birth.

PubMed

Murphy, Kellie E; Willan, Andrew R; Hannah, Mary E; Ohlsson, Arne; Kelly, Edmond N; Matthews, Stephen G; Saigal, Saroj; Asztalos, Elizabeth; Ross, Susan; Delisle, Marie-France; Amankwah, Kofi; Guselle, Patricia; Gafni, Amiram; Lee, Shoo K; Armson, B Anthony

2012-05-01

To estimate the effect of multiple courses of antenatal corticosteroids on neonatal size, controlling for gestational age at birth and other confounders, and to determine whether there was a dose-response relationship between number of courses of antenatal corticosteroids and neonatal size. This is a secondary analysis of the Multiple Courses of Antenatal Corticosteroids for Preterm Birth Study, a double-blind randomized controlled trial of single compared with multiple courses of antenatal corticosteroids in women at risk for preterm birth and in which fetuses administered multiple courses of antenatal corticosteroids weighed less, were shorter, and had smaller head circumferences at birth. All women (n=1,858) and children (n=2,304) enrolled in the Multiple Courses of Antenatal Corticosteroids for Preterm Birth Study were included in the current analysis. Multiple linear regression analyses were undertaken. Compared with placebo, neonates in the antenatal corticosteroids group were born earlier (estimated difference and confidence interval [CI]: -0.428 weeks, CI -0.10264 to -0.75336; P=.01). Controlling for gestational age at birth and confounding factors, multiple courses of antenatal corticosteroids were associated with a decrease in birth weight (-33.50 g, CI -66.27120 to -0.72880; P=.045), length (-0.339 cm, CI -0.6212 to -0.05676]; P=.019), and head circumference (-0.296 cm, -0.45672 to -0.13528; P<.001). For each additional course of antenatal corticosteroids, there was a trend toward an incremental decrease in birth weight, length, and head circumference. Fetuses exposed to multiple courses of antenatal corticosteroids were smaller at birth. The reduction in size was partially attributed to being born at an earlier gestational age but also was attributed to decreased fetal growth. Finally, a dose-response relationship exists between the number of corticosteroid courses and a decrease in fetal growth. The long-term effect of these findings is unknown. ClinicalTrials.gov, www.clinicaltrials.gov, NCT00187382. II.

Inverse Association between Fruit and Vegetable Intake and BMI even after Controlling for Demographic, Socioeconomic and Lifestyle Factors

PubMed Central

Heo, Moonseong; Kim, Ryung S.; Wylie-Rosett, Judith; Allison, David B.; Heymsfield, Steve B.; Faith, Myles S.

2011-01-01

Objective To estimate fruit and vegetable (FV) intake levels of US adult population and evaluate the association between FV intake and BMI status after controlling for confounding demographic, socioeconomic and lifestyle factors. We also sought to identify moderating factors. Methods We used 2007 Behavior Risk Factors Surveillance System (N > 400,000) data. FV intake was dichotomized as ≥5 servings (FV5+) versus <5 servings/day. BMI status was categorized as normal, overweight, and obese. Identification of moderators was performed by testing interactions between BMI status and other variables using bivariate analyses followed by multiple logistic regression analysis incorporating complex survey sampling design features. Results Only 24.6% of US adults consumed ≥5 servings per day and less than 4% consumed 9 or more servings. Overweight (% FV5+ = 23.9%) and obese (21.9%) groups consumed significantly less FV than the normal-weight (27.4%) group (p < 0.0001). This inverse association remained significant even after controlling for potential confounding factors. Multivariate analysis identified five significant moderators (p < 0.0001) after controlling for all evaluated variables: race, sex, smoking status, health coverage, and physical activity. Notably, physically inactive obese males tended to consume the least FV (% FV5+ = 14.7%). Conclusion Current US population FV intake level is below recommended levels. The inverse association between FV intake and obesity was significant and was moderated by demographic, socioeconomic status, and lifestyle factors. These factors should be considered when developing policies and interventions to increase FV intake. PMID:22248995

Evaluating the impact of implementation factors on family-based prevention programming: methods for strengthening causal inference.

PubMed

Crowley, D Max; Coffman, Donna L; Feinberg, Mark E; Greenberg, Mark T; Spoth, Richard L

2014-04-01

Despite growing recognition of the important role implementation plays in successful prevention efforts, relatively little work has sought to demonstrate a causal relationship between implementation factors and participant outcomes. In turn, failure to explore the implementation-to-outcome link limits our understanding of the mechanisms essential to successful programming. This gap is partially due to the inability of current methodological procedures within prevention science to account for the multitude of confounders responsible for variation in implementation factors (i.e., selection bias). The current paper illustrates how propensity and marginal structural models can be used to improve causal inferences involving implementation factors not easily randomized (e.g., participant attendance). We first present analytic steps for simultaneously evaluating the impact of multiple implementation factors on prevention program outcome. Then, we demonstrate this approach for evaluating the impact of enrollment and attendance in a family program, over and above the impact of a school-based program, within PROSPER, a large-scale real-world prevention trial. Findings illustrate the capacity of this approach to successfully account for confounders that influence enrollment and attendance, thereby more accurately representing true causal relations. For instance, after accounting for selection bias, we observed a 5% reduction in the prevalence of 11th grade underage drinking for those who chose to receive a family program and school program compared to those who received only the school program. Further, we detected a 7% reduction in underage drinking for those with high attendance in the family program.

Arsenic exposure assists ccm3 genetic polymorphism in elevating blood pressure

PubMed Central

Liu, Xinxia; Xing, Xiumei; Zhang, Huimin; Yun, Jianpei; Ou, Xiaoyan; Su, Xiaolin; Lu, Yao; Sun, Yi; Yang, Yarui; Jiang, Jun; Cui, Dong; Zhuang, Zhixiong; He, Yun

2018-01-01

Epidemiologic study has suggested that arsenic exposure is positively related to increased blood pressure. However, the underlying mechanism concerning interaction between genetic polymorphisms and arsenic exposure remains unclear. In present study, within 395 Chinese, the effects of interaction between arsenic exposure and CCM3 gene polymorphisms on elevation of blood pressure were probed by multiple Logistic regression models after adjusting for confounding factors. Firstly, we found that serum arsenic was positively associated with blood pressure, cholesterol, glucose and C-reactive protein. Then, adjusted for confounding factors of age, gender, smoking, alcohol consumption, BMI and degree of education, arsenic exposure incurred the hazard of increased systolic pressure and diastolic pressure, with odds ratios (ORs) being 1.725 and 1.425, respectively. Distinctly, we found that interactions between rs3804610* rs9818496, rs6784267*rs9818496, and rs3804610* rs6784267 variant genotype can increase significantly risks of SBP. Additionally, interactions between rs9818496, rs3804610 and rs6784267 genotypic variantions and arsenic exposure boosted the hazard of increased systolic pressure, with ORs being 1.496, 1.496 and 1.312. In conclusion, our fingdings suggest that As exposure of population can assist CCM3 polymorphism in elevating SBP. PMID:29435151

Frequency of soup intake and amount of dietary fiber intake are inversely associated with plasma leptin concentrations in Japanese adults.

PubMed

Kuroda, Motonaka; Ohta, Masanori; Okufuji, Tatsuya; Takigami, Chieko; Eguchi, Masafumi; Hayabuchi, Hitomi; Ikeda, Masaharu

2010-06-01

Previous studies have shown that the intake of soup negatively correlates with the body mass index (BMI), suggesting that soup intake reduces the risk of obesity. In this study, to clarify the association of the intake of soup and various nutrients with plasma leptin concentration, a cross-sectional study on 504 Japanese adults aged 20-76 years (103 men and 401 women) was performed. The intake of soup and various nutrients was investigated by food frequency questionnaires. Plasma leptin concentration was measured in fasting blood by radioimmunoassay. The correlation was analyzed by multiple regression analysis. The average frequency of soup intake was 7.6 times/week. The average plasma leptin concentration was 7.76 ng/ml. After adjusting the confounding factors, the frequency of soup intake has a significant inverse association with plasma leptin concentration. Among the macronutrients, only dietary fiber intake negatively correlated with plasma leptin concentration after the adjustment for potential confounding factors. These results suggest that the intakes of soup and dietary fiber were negatively correlated with plasma leptin concentration in Japanese adults. Copyright 2010 Elsevier Ltd. All rights reserved.

Residential proximity to electromagnetic field sources and birth weight: Minimizing residual confounding using multiple imputation and propensity score matching.

PubMed

de Vocht, Frank; Lee, Brian

2014-08-01

Studies have suggested that residential exposure to extremely low frequency (50 Hz) electromagnetic fields (ELF-EMF) from high voltage cables, overhead power lines, electricity substations or towers are associated with reduced birth weight and may be associated with adverse birth outcomes or even miscarriages. We previously conducted a study of 140,356 singleton live births between 2004 and 2008 in Northwest England, which suggested that close residential proximity (≤ 50 m) to ELF-EMF sources was associated with reduced average birth weight of 212 g (95%CI: -395 to -29 g) but not with statistically significant increased risks for other adverse perinatal outcomes. However, the cohort was limited by missing data for most potentially confounding variables including maternal smoking during pregnancy, which was only available for a small subgroup, while also residual confounding could not be excluded. This study, using the same cohort, was conducted to minimize the effects of these problems using multiple imputation to address missing data and propensity score matching to minimize residual confounding. Missing data were imputed using multiple imputation using chained equations to generate five datasets. For each dataset 115 exposed women (residing ≤ 50 m from a residential ELF-EMF source) were propensity score matched to 1150 unexposed women. After doubly robust confounder adjustment, close proximity to a residential ELF-EMF source remained associated with a reduction in birth weight of -116 g (95% confidence interval: -224:-7 g). No effect was found for proximity ≤ 100 m compared to women living further away. These results indicate that although the effect size was about half of the effect previously reported, close maternal residential proximity to sources of ELF-EMF remained associated with suboptimal fetal growth. Copyright © 2014 Elsevier Ltd. All rights reserved.

Does environmental confounding mask pleiotropic effects of a multiple sclerosis susceptibility variant on vitamin D in psychosis?

PubMed

Iyegbe, Conrad O; Acharya, Anita; Lally, John; Gardner-Sood, Poonam; Smith, Louise S; Smith, Shubulade; Murray, Robin; Howes, Oliver; Gaughran, Fiona

2015-01-01

This work addresses the existing and emerging evidence of overlap within the environmental and genetic profiles of multiple sclerosis (MS) and schizophrenia. To investigate whether a genetic risk factor for MS (rs703842), whose variation is indicative of vitamin D status in the disorder, could also be a determinant of vitamin D status in chronic psychosis patients. A cohort of 224 chronic psychosis cases was phenotyped and biologically profiled. The relationship between rs703842 and physiological vitamin D status in the blood plasma was assessed by logistic regression. Deficiency was defined as a blood plasma concentration below 10 ng/µl. Potential environmental confounders of the vitamin D status were considered as part of the analysis. We report suggestive evidence of an association with vitamin D status in established psychosis (ß standardized=0.51, P=0.04). The logistic model fit significantly benefited from controlling for body mass index, depression and ethnicity (χ (2)=91.7; 2 degrees of freedom (df); P=1.2×10(20)). The results suggest that, in addition to lifestyle changes that accompany the onset of illness, vitamin D dysregulation in psychosis has a genetic component that links into MS. Further, comprehensive studies are needed to evaluate this prospect.

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.

Real-Time Assessment of Fatigue in Patients With Multiple Sclerosis: How Does It Relate to Commonly Used Self-Report Fatigue Questionnaires?

PubMed

Heine, Martin; van den Akker, Lizanne Eva; Blikman, Lyan; Hoekstra, Trynke; van Munster, Erik; Verschuren, Olaf; Visser-Meily, Anne; Kwakkel, Gert

2016-11-01

(1) To assess real-time patterns of fatigue; (2) to assess the association between a real-time fatigue score and 3 commonly used questionnaires (Checklist Individual Strength [CIS] fatigue subscale, Modified Fatigue Impact Scale (MFIS), and Fatigue Severity Scale [FSS]); and (3) to establish factors that confound the association between the real-time fatigue score and the conventional fatigue questionnaires in patients with multiple sclerosis (MS). Cross-sectional study. MS-specialized outpatient facility. Ambulant patients with MS (N=165) experiencing severe self-reported fatigue. Not applicable. A real-time fatigue score was assessed by sending participants 4 text messages on a particular day (How fatigued do you feel at this moment?; score range, 0-10). Latent class growth mixed modeling was used to determine diurnal patterns of fatigue. Regression analyses were used to assess the association between the mean real-time fatigue score and the CIS fatigue subscale, MFIS, and FSS. Significant associations were tested for candidate confounders (eg, disease severity, work status, sleepiness). Four significantly different fatigue profiles were identified by the real-time fatigue score, namely a stable high (n=79), increasing (n=57), stable low (n=16), and decreasing (n=13). The conventional questionnaires correlated poorly (r<.300) with the real-time fatigue score. The Epworth Sleepiness Scale significantly reduced the regression coefficient between the real-time fatigue score and conventional questionnaires, ranging from 15.4% to 35%. Perceived fatigue showed 4 different diurnal patterns in patients with MS. Severity of sleepiness is an important confounder to take into account in the assessment of fatigue. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

NASA Astrophysics Data System (ADS)

Maspero, Matteo; Seevinck, Peter R.; Schubert, Gerald; Hoesl, Michaela A. U.; van Asselen, Bram; Viergever, Max A.; Lagendijk, Jan J. W.; Meijer, Gert J.; van den Berg, Cornelis A. T.

2017-02-01

Magnetic resonance (MR)-only radiotherapy treatment planning requires pseudo-CT (pCT) images to enable MR-based dose calculations. To verify the accuracy of MR-based dose calculations, institutions interested in introducing MR-only planning will have to compare pCT-based and computer tomography (CT)-based dose calculations. However, interpreting such comparison studies may be challenging, since potential differences arise from a range of confounding factors which are not necessarily specific to MR-only planning. Therefore, the aim of this study is to identify and quantify the contribution of factors confounding dosimetric accuracy estimation in comparison studies between CT and pCT. The following factors were distinguished: set-up and positioning differences between imaging sessions, MR-related geometric inaccuracy, pCT generation, use of specific calibration curves to convert pCT into electron density information, and registration errors. The study comprised fourteen prostate cancer patients who underwent CT/MRI-based treatment planning. To enable pCT generation, a commercial solution (MRCAT, Philips Healthcare, Vantaa, Finland) was adopted. IMRT plans were calculated on CT (gold standard) and pCTs. Dose difference maps in a high dose region (CTV) and in the body volume were evaluated, and the contribution to dose errors of possible confounding factors was individually quantified. We found that the largest confounding factor leading to dose difference was the use of different calibration curves to convert pCT and CT into electron density (0.7%). The second largest factor was the pCT generation which resulted in pCT stratified into a fixed number of tissue classes (0.16%). Inter-scan differences due to patient repositioning, MR-related geometric inaccuracy, and registration errors did not significantly contribute to dose differences (0.01%). The proposed approach successfully identified and quantified the factors confounding accurate MRI-based dose calculation in the prostate. This study will be valuable for institutions interested in introducing MR-only dose planning in their clinical practice.

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.

The effect of heartburn and acid reflux on the severity of nausea and vomiting of pregnancy

PubMed Central

Gill, Simerpal Kaur; Maltepe, Caroline; Koren, Gideon

2009-01-01

BACKGROUND: Heartburn (HB) and acid reflux (RF) in the non-pregnant population can cause nausea and vomiting; therefore, it is plausible that in women with nausea and vomiting of pregnancy (NVP), HB/RF may increase the severity of symptoms. OBJECTIVE: To determine whether HB/RF during pregnancy contribute to increased severity of NVP. METHODS: A prospectively collected cohort of women who were experiencing NVP and HB, RF or both (n=194) was studied. The Pregnancy-Unique Quantification of Emesis and Nausea (PUQE) scale and its Well-being scale was used to compare the severity of the study cohort’s symptoms. This cohort was compared with a group of women experiencing NVP but no HB/RF (n=188). Multiple linear regression was used to control for the effects of confounding factors. RESULTS: Women with HB/RF reported higher PUQE scores (9.6±2.6) compared with controls (8.9±2.6) (P=0.02). Similarly, Well-being scores for women experiencing HB/RF were lower (4.3±2.1) compared with controls (4.9±2.0) (P=0.01). Multiple linear regression analysis demonstrated that increased PUQE scores (P=0.003) and decreased Well-being scores (P=0.005) were due to the presence of HB/RF as opposed to confounding factors such as pre-existing gastrointestinal conditions/symptoms, hyperemesis gravidarum in previous pregnancies and comorbidities. CONCLUSION: The present cohort study is the first to demonstrate that HB/RF are associated with increased severity of NVP. Managing HB/RF may improve the severity of NVP. PMID:19373420

Association of Lifestyle-Related Comorbidities With Periodontitis

PubMed Central

Lee, Jae-Hong; Lee, Jung-Seok; Park, Jin-Young; Choi, Jung-Kyu; Kim, Dong-Wook; Kim, Young-Taek; Choi, Seong-Ho

2015-01-01

Abstract The aim of this study was to determine the association of periodontitis with lifestyle-related comorbidities (LCs) using data in the Korean National Health Insurance Cohort Database from 2002 to 2013. This was a retrospective study involving a large national cohort with patient samples (representing 2% of the total Korean population) stratified on the basis of sociodemographic information. Using this precisely extracted database, the correlations between LCs (cerebral infarction, angina pectoris, myocardial infarction, hypertension, diabetes mellitus, rheumatoid arthritis, erectile dysfunction, osteoporosis, and obesity) and periodontitis were investigated while adjusting for confounding bias. Univariate and multiple logistic regression analyses were used to evaluate differences in variable factors. Among a total of 1,025,340 samples, 321,103 (31.3%) cases were diagnosed with periodontitis. Statistically significant associations were found between all LCs except myocardial infarction and periodontitis (P < 0.005). Periodontitis is significantly and positively correlated with LCs (except for myocardial infarction) after adjusting for confounding bias. In particular, lifestyle-related diseases, erectile dysfunction, and osteoporosis seem to be intimately related to periodontitis. PMID:26376407

Design of Experiments with Multiple Independent Variables: A Resource Management Perspective on Complete and Reduced Factorial Designs

PubMed Central

Collins, Linda M.; Dziak, John J.; Li, Runze

2009-01-01

An investigator who plans to conduct experiments with multiple independent variables must decide whether to use a complete or reduced factorial design. This article advocates a resource management perspective on making this decision, in which the investigator seeks a strategic balance between service to scientific objectives and economy. Considerations in making design decisions include whether research questions are framed as main effects or simple effects; whether and which effects are aliased (confounded) in a particular design; the number of experimental conditions that must be implemented in a particular design and the number of experimental subjects the design requires to maintain the desired level of statistical power; and the costs associated with implementing experimental conditions and obtaining experimental subjects. In this article four design options are compared: complete factorial, individual experiments, single factor, and fractional factorial designs. Complete and fractional factorial designs and single factor designs are generally more economical than conducting individual experiments on each factor. Although relatively unfamiliar to behavioral scientists, fractional factorial designs merit serious consideration because of their economy and versatility. PMID:19719358

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

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

USDA-ARS?s Scientific Manuscript database

Epidemiology of dietary components and disease risk limits interpretability due to 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 ...

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

USDA-ARS?s Scientific Manuscript database

Epidemiology of dietary components and disease risk limits interpretability due to potential residual confounding by correlated dietary components. Dietary pattern analyses by factor analysis or partial least squares may overcome this limitation. To examine confounding by dietary pattern as well as ...

Confounder summary scores when comparing the effects of multiple drug exposures.

PubMed

Cadarette, Suzanne M; Gagne, Joshua J; Solomon, Daniel H; Katz, Jeffrey N; Stürmer, Til

2010-01-01

Little information is available comparing methods to adjust for confounding when considering multiple drug exposures. We compared three analytic strategies to control for confounding based on measured variables: conventional multivariable, exposure propensity score (EPS), and disease risk score (DRS). Each method was applied to a dataset (2000-2006) recently used to examine the comparative effectiveness of four drugs. The relative effectiveness of risedronate, nasal calcitonin, and raloxifene in preventing non-vertebral fracture, were each compared to alendronate. EPSs were derived both by using multinomial logistic regression (single model EPS) and by three separate logistic regression models (separate model EPS). DRSs were derived and event rates compared using Cox proportional hazard models. DRSs derived among the entire cohort (full cohort DRS) was compared to DRSs derived only among the referent alendronate (unexposed cohort DRS). Less than 8% deviation from the base estimate (conventional multivariable) was observed applying single model EPS, separate model EPS or full cohort DRS. Applying the unexposed cohort DRS when background risk for fracture differed between comparison drug exposure cohorts resulted in -7 to + 13% deviation from our base estimate. With sufficient numbers of exposed and outcomes, either conventional multivariable, EPS or full cohort DRS may be used to adjust for confounding to compare the effects of multiple drug exposures. However, our data also suggest that unexposed cohort DRS may be problematic when background risks differ between referent and exposed groups. Further empirical and simulation studies will help to clarify the generalizability of our findings.

Integrative assessment of multiple pesticides as risk factors for non-Hodgkin's lymphoma among men.

PubMed

De Roos, A J; Zahm, S H; Cantor, K P; Weisenburger, D D; Holmes, F F; Burmeister, L F; Blair, A

2003-09-01

An increased rate of non-Hodgkin's lymphoma (NHL) has been repeatedly observed among farmers, but identification of specific exposures that explain this observation has proven difficult. During the 1980s, the National Cancer Institute conducted three case-control studies of NHL in the midwestern United States. These pooled data were used to examine pesticide exposures in farming as risk factors for NHL in men. The large sample size (n = 3417) allowed analysis of 47 pesticides simultaneously, controlling for potential confounding by other pesticides in the model, and adjusting the estimates based on a prespecified variance to make them more stable. Reported use of several individual pesticides was associated with increased NHL incidence, including organophosphate insecticides coumaphos, diazinon, and fonofos, insecticides chlordane, dieldrin, and copper acetoarsenite, and herbicides atrazine, glyphosate, and sodium chlorate. A subanalysis of these "potentially carcinogenic" pesticides suggested a positive trend of risk with exposure to increasing numbers. Consideration of multiple exposures is important in accurately estimating specific effects and in evaluating realistic exposure scenarios.

Relationship of type of work with health-related quality of life.

PubMed

Kawabe, Yuri; Nakamura, Yasuyuki; Kikuchi, Sayuri; Suzukamo, Yoshimi; Murakami, Yoshitaka; Tanaka, Taichiro; Takebayashi, Toru; Okayama, Akira; Miura, Katsuyuki; Okamura, Tomonori; Fukuhara, Shunichi; Ueshima, Hirotsugu

2015-12-01

To examine the relation of work type with health-related quality of life (HRQoL) in healthy workers. We cross-sectionally examined 4427 (3605 men and 822 women) healthy workers in Japan, aged 19-69 years. We assessed HRQoL based on scores for five scales of the SF-36. Multiple regression was applied to examine the relation of work type (nighttime, shift, day to night, and daytime) with the five HRQoL norm-based scores, lower scores of which indicate poorer health status, adjusted for confounding factors, including sleeping duration. Shiftwork was inversely related to role physical [regression estimate (β) = -2.12, 95 % confidence intervals (CI) -2.94, -1.30, P < 0.001], general health (β = -1.37, 95 % CI -2.01, -0.72, P < 0.001), role emotional (β = -1.24, 95% CI -1.98, -0.50, P < 0.001), and mental health (β = -1.31, 95% CI -2.01, -0.63, P < 0.001) independent of confounding factors, but not to vitality. Day-to-nighttime work was inversely related to all the five HRQoL subscales (Ps 0.012 to <0.001). Shiftwork was significantly inversely related to four out of the five HRQoL, except for vitality, and day-to-nighttime work was significantly inversely related to all five HRQoL, independent of demographic and lifestyle factors.

Factors associated with higher oxytocin requirements in labor.

PubMed

Frey, Heather A; Tuuli, Methodius G; England, Sarah K; Roehl, Kimberly A; Odibo, Anthony O; Macones, George A; Cahill, Alison G

2015-09-01

To identify clinical characteristics associated with high maximum oxytocin doses in women who achieve complete cervical dilation. A retrospective nested case-control study was performed within a cohort of all term women at a single center between 2004 and 2008 who reached the second stage of labor. Cases were defined as women who had a maximum oxytocin dose during labor >20 mu/min, while women in the control group had a maximum oxytocin dose during labor of ≤20 mu/min. Exclusion criteria included no oxytocin administration during labor, multiple gestations, major fetal anomalies, nonvertex presentation, and prior cesarean delivery. Multiple maternal, fetal, and labor factors were evaluated with univariable analysis and multivariable logistic regression. Maximum oxytocin doses >20 mu/min were administered to 108 women (3.6%), while 2864 women received doses ≤20 mu/min. Factors associated with higher maximum oxytocin dose after adjusting for relevant confounders included maternal diabetes, birthweight >4000 g, intrapartum fever, administration of magnesium, and induction of labor. Few women who achieve complete cervical dilation require high doses of oxytocin. We identified maternal, fetal and labor factors that characterize this group of parturients.

Developing hazelnut tissue culture medium free of ion confounding

USDA-ARS?s Scientific Manuscript database

The general approach for tissue culture medium optimization is to use salts as factors in experimental design and analysis. However, using salts as factors leads to ion confounding, making it difficult to detect the effects of individual ions on particular growth responses. This study focused on tes...

Alexithymia and burnout in nursing students.

PubMed

Katsifaraki, Maria; Tucker, Philip

2013-11-01

Although previous studies have indicated an association between alexithymia and burnout, they have not controlled for well-established organizational factors, depression, and coping mechanisms that could confound the relationship. This study investigated the association between alexithymia and occupational burnout. One hundred eighty-three nursing students were assessed up to 3 months before graduating from their program. Alexithymia was measured with the Toronto Alexithymia Scale, occupational burnout was measured with the Maslach Burnout Inventory, work-related factors were measured with the Areas of Worklife Survey, depression was measured with Beck Depression Inventory-II, and coping strategies were measured with the COPE Dispositional Inventory. Hierarchical multiple regressions indicated that externally oriented thinking style was significantly associated with personal accomplishment and depersonalization after adjusting for depression, coping, and work-related factors. The results indicate that only a single aspect of the alexithymia construct serves as a possibly independent predisposing factor for specific burnout dimensions. Copyright 2013, SLACK Incorporated.

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

Overcoming barriers to public understanding of climate change

NASA Astrophysics Data System (ADS)

Hayhoe, K.

2012-12-01

Humans are interfering with global climate, increasing the risk of serious consequences for human society and the natural environment. As the scientific evidence builds, however, so does the public controversy surrounding this issue. Why is climate change so contentious? What makes it so hard to comprehend? I argue that there is no single reason for this, but rather a perfect storm of multiple confounding factors; scientific, historical, ideological, psychological and even physiological in nature. Education—of both the messengers and the audience—can play a critical role in surmounting many of the common barriers to understanding, accepting, and acting this important issue.

Human Health and Exposure to Electromagnetic Radiation

DTIC Science & Technology

1992-07-01

electromagnetic field exposures and cancer. Studies of electrical and electronic workers are suggestive of such a link, but are subject to the confounding factor ...associations between cancer and electrical installations 108 51 Factors associated with increased risk of childhood cancer in the Denver studies 109 52...It is important in epidemiological studies to make Arenuous efforts to adjust for possible confounding factors , many - in particular the early

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.

Evaluating the Impact of Implementation Factors on Family-Based Prevention Programming: Methods for Strengthening Causal Inference

PubMed Central

Crowley, D. Max; Coffman, Donna L.; Feinberg, Mark; Greenberg, Mark; Spoth, Richard

2013-01-01

Despite growing recognition of the important role implementation plays in successful prevention efforts, relatively little work has sought to demonstrate a causal relationship between implementation factors and participant outcomes. In turn, failure to explore the implementation-to-outcome link limits our understanding of the mechanisms essential to successful programming. This gap is partially due to the inability of current methodological procedures within prevention science to account for the multitude of confounders responsible for variation in implementation factors (i.e., selection bias). The current paper illustrates how propensity and marginal structural models can be used to improve causal inferences involving implementation factors not easily randomized (e.g., participant attendance). We first present analytic steps for simultaneously evaluating the impact of multiple implementation factors on prevention program outcome. Then we demonstrate this approach for evaluating the impact of enrollment and attendance in a family program, over and above the impact of a school-based program, within PROSPER, a large scale real-world prevention trial. Findings illustrate the capacity of this approach to successfully account for confounders that influence enrollment and attendance, thereby more accurately representing true causal relations. For instance, after accounting for selection bias, we observed a 5% reduction in the prevalence of 11th grade underage drinking for those who chose to receive a family program and school program compared to those who received only the school program. Further, we detected a 7% reduction in underage drinking for those with high attendance in the family program. PMID:23430578

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.

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.

Leveraging Hierarchical Population Structure in Discrete Association Studies

PubMed Central

Carlson, Jonathan; Kadie, Carl; Mallal, Simon; Heckerman, David

2007-01-01

Population structure can confound the identification of correlations in biological data. Such confounding has been recognized in multiple biological disciplines, resulting in a disparate collection of proposed solutions. We examine several methods that correct for confounding on discrete data with hierarchical population structure and identify two distinct confounding processes, which we call coevolution and conditional influence. We describe these processes in terms of generative models and show that these generative models can be used to correct for the confounding effects. Finally, we apply the models to three applications: identification of escape mutations in HIV-1 in response to specific HLA-mediated immune pressure, prediction of coevolving residues in an HIV-1 peptide, and a search for genotypes that are associated with bacterial resistance traits in Arabidopsis thaliana. We show that coevolution is a better description of confounding in some applications and conditional influence is better in others. That is, we show that no single method is best for addressing all forms of confounding. Analysis tools based on these models are available on the internet as both web based applications and downloadable source code at http://atom.research.microsoft.com/bio/phylod.aspx. PMID:17611623

Trimodel Mammography with Perfect Coregistration

DTIC Science & Technology

2017-02-01

background, the major confounding factor in reading mammography; the imaging characteristics suggest that this contrast mechanism would be preferable...image with enhanced edges and reduced anatomical background, the major confounding factor in reading mammography; the imaging characteristics suggest...subjects, vertebrate animals , biohazards, and/or select agents Describe significant deviations, unexpected outcomes, or changes in approved protocols

Epidemiologic methods in clinical trials.

PubMed

Rothman, K J

1977-04-01

Epidemiologic methods developed to control confounding in non-experimental studies are equally applicable for experiments. In experiments, most confounding is usually controlled by random allocation of subjects to treatment groups, but randomization does not preclude confounding except for extremely large studies, the degree of confounding expected being inversely related to the size of the treatment groups. In experiments, as in non-experimental studies, the extent of confounding for each risk indicator should be assessed, and if sufficiently large, controlled. Confounding is properly assessed by comparing the unconfounded effect estimate to the crude effect estimate; a common error is to assess confounding by statistical tests of significance. Assessment of confounding involves its control as a prerequisite. Control is most readily and cogently achieved by stratification of the data, though with many factors to control simultaneously, multivariate analysis or a combination of multivariate analysis and stratification might be necessary.

Conditional Random Fields for Fast, Large-Scale Genome-Wide Association Studies

PubMed Central

Huang, Jim C.; Meek, Christopher; Kadie, Carl; Heckerman, David

2011-01-01

Understanding the role of genetic variation in human diseases remains an important problem to be solved in genomics. An important component of such variation consist of variations at single sites in DNA, or single nucleotide polymorphisms (SNPs). Typically, the problem of associating particular SNPs to phenotypes has been confounded by hidden factors such as the presence of population structure, family structure or cryptic relatedness in the sample of individuals being analyzed. Such confounding factors lead to a large number of spurious associations and missed associations. Various statistical methods have been proposed to account for such confounding factors such as linear mixed-effect models (LMMs) or methods that adjust data based on a principal components analysis (PCA), but these methods either suffer from low power or cease to be tractable for larger numbers of individuals in the sample. Here we present a statistical model for conducting genome-wide association studies (GWAS) that accounts for such confounding factors. Our method scales in runtime quadratic in the number of individuals being studied with only a modest loss in statistical power as compared to LMM-based and PCA-based methods when testing on synthetic data that was generated from a generalized LMM. Applying our method to both real and synthetic human genotype/phenotype data, we demonstrate the ability of our model to correct for confounding factors while requiring significantly less runtime relative to LMMs. We have implemented methods for fitting these models, which are available at http://www.microsoft.com/science. PMID:21765897

Racial/Ethnic Disparities in Primary Care Quality Among Type 2 Diabetes Patients, Medical Expenditure Panel Survey, 2012.

PubMed

Hu, Ruwei; Shi, Leiyu; Liang, Hailun; Haile, Geraldine Pierre; Lee, De-Chih

2016-08-04

Racial and ethnic disparities exist in diabetes prevalence, access to diabetes care, diabetes-related complications and mortality rates, and the quality of diabetes care among Americans. We explored racial and ethnic disparities in primary care quality among Americans with type 2 diabetes. We analyzed data on adults with type 2 diabetes derived from the household component of the 2012 Medical Expenditure Panel Survey. Multiple regression and multivariate logistic regressions were used to examine the association between race/ethnicity and primary care attributes related to first contact, longitudinality, comprehensiveness, and coordination, and clusters of confounding factors were added sequentially. Preliminary findings indicated differences in primary care quality between racial/ethnic minorities and whites across measures of first contact, longitudinality, comprehensiveness, and coordination. After controlling for confounding factors, these differences were no longer apparent; all racial/ethnic categories showed similar rates of primary care quality according to the 4 primary care domains of interest in the study. Results indicate equitable primary care quality for type 2 diabetes patients across 4 key domains of primary care after controlling for socioeconomic characteristics. Additional research is necessary to support these findings, particularly when considering smaller racial/ethnic groups and investigating outcomes related to diabetes.

Evaluation of subjective thermal strain in different kitchen working environments using subjective judgment scales.

PubMed

Haruyama, Yasuo; Muto, Takashi; Matsuzuki, Hiroe; Ito, Akiyoshi; Tomita, Shigeru; Muto, Shigeki; Haratani, Takashi; Seo, Akihiko; Ayabe, Makoto; Katamoto, Shizuo

2010-01-01

To elucidate the subjective thermal strain of workers in kitchen working environments, we performed a cross-sectional study involving 991 workers in 126 kitchen facilities in Japan, using a self-reporting questionnaire survey and subjective judgment scales (SJS). The ambient temperature, mean radiant temperature (MRT), and wet-bulb globe temperature (WBGT) index were measured in 10 kitchen facilities of the 126 kitchens. The association of SJS with the types of kitchen was estimated by multiple logistic regression models. Of the 991 kitchen workers, 809 (81%) responded to the questionnaire survey. Compared with the electric kitchens, the proportion of workers who perceived the room temperature as hot to very hot was significantly higher, and the ambient temperature, MRT, and WBGT were significantly higher in the gas kitchens. Compared with the electric kitchens, workers in gas kitchens had a more than fivefold (males) and tenfold (females) higher SJS adjusted for confounding factors (male odds ratio (OR), 5.13; 95% confidence interval (CI), 1.65-15.9; and female OR, 10.9; 95%CI, 3.89-30.5). Although SJS was affected by some confounding factors, our results suggest that workers in gas kitchens might be exposed to a higher heat strains than those in electric kitchens.

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.

Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports.

PubMed

Hackshaw, Allan; Morris, Joan K; Boniface, Sadie; Tang, Jin-Ling; Milenković, Dušan

2018-01-24

To use the relation between cigarette consumption and cardiovascular disease to quantify the risk of coronary heart disease and stroke for light smoking (one to five cigarettes/day). Systematic review and meta-analysis. Medline 1946 to May 2015, with manual searches of references. Prospective cohort studies with at least 50 events, reporting hazard ratios or relative risks (both hereafter referred to as relative risk) compared with never smokers or age specific incidence in relation to risk of coronary heart disease or stroke. MOOSE guidelines were followed. For each study, the relative risk was estimated for smoking one, five, or 20 cigarettes per day by using regression modelling between risk and cigarette consumption. Relative risks were adjusted for at least age and often additional confounders. The main measure was the excess relative risk for smoking one cigarette per day (RR 1_per_day -1) expressed as a proportion of that for smoking 20 cigarettes per day (RR 20_per_day -1), expected to be about 5% assuming a linear relation between risk and consumption (as seen with lung cancer). The relative risks for one, five, and 20 cigarettes per day were also pooled across all studies in a random effects meta-analysis. Separate analyses were done for each combination of sex and disorder. The meta-analysis included 55 publications containing 141 cohort studies. Among men, the pooled relative risk for coronary heart disease was 1.48 for smoking one cigarette per day and 2.04 for 20 cigarettes per day, using all studies, but 1.74 and 2.27 among studies in which the relative risk had been adjusted for multiple confounders. Among women, the pooled relative risks were 1.57 and 2.84 for one and 20 cigarettes per day (or 2.19 and 3.95 using relative risks adjusted for multiple factors). Men who smoked one cigarette per day had 46% of the excess relative risk for smoking 20 cigarettes per day (53% using relative risks adjusted for multiple factors), and women had 31% of the excess risk (38% using relative risks adjusted for multiple factors). For stroke, the pooled relative risks for men were 1.25 and 1.64 for smoking one or 20 cigarettes per day (1.30 and 1.56 using relative risks adjusted for multiple factors). In women, the pooled relative risks were 1.31 and 2.16 for smoking one or 20 cigarettes per day (1.46 and 2.42 using relative risks adjusted for multiple factors). The excess risk for stroke associated with one cigarette per day (in relation to 20 cigarettes per day) was 41% for men and 34% for women (or 64% and 36% using relative risks adjusted for multiple factors). Relative risks were generally higher among women than men. Smoking only about one cigarette per day carries a risk of developing coronary heart disease and stroke much greater than expected: around half that for people who smoke 20 per day. No safe level of smoking exists for cardiovascular disease. Smokers should aim to quit instead of cutting down to significantly reduce their risk of these two common major disorders. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports

PubMed Central

Morris, Joan K; Boniface, Sadie; Tang, Jin-Ling; Milenković, Dušan

2018-01-01

Abstract Objective To use the relation between cigarette consumption and cardiovascular disease to quantify the risk of coronary heart disease and stroke for light smoking (one to five cigarettes/day). Design Systematic review and meta-analysis. Data sources Medline 1946 to May 2015, with manual searches of references. Eligibility criteria for selecting studies Prospective cohort studies with at least 50 events, reporting hazard ratios or relative risks (both hereafter referred to as relative risk) compared with never smokers or age specific incidence in relation to risk of coronary heart disease or stroke. Data extraction/synthesis MOOSE guidelines were followed. For each study, the relative risk was estimated for smoking one, five, or 20 cigarettes per day by using regression modelling between risk and cigarette consumption. Relative risks were adjusted for at least age and often additional confounders. The main measure was the excess relative risk for smoking one cigarette per day (RR1_per_day−1) expressed as a proportion of that for smoking 20 cigarettes per day (RR20_per_day−1), expected to be about 5% assuming a linear relation between risk and consumption (as seen with lung cancer). The relative risks for one, five, and 20 cigarettes per day were also pooled across all studies in a random effects meta-analysis. Separate analyses were done for each combination of sex and disorder. Results The meta-analysis included 55 publications containing 141 cohort studies. Among men, the pooled relative risk for coronary heart disease was 1.48 for smoking one cigarette per day and 2.04 for 20 cigarettes per day, using all studies, but 1.74 and 2.27 among studies in which the relative risk had been adjusted for multiple confounders. Among women, the pooled relative risks were 1.57 and 2.84 for one and 20 cigarettes per day (or 2.19 and 3.95 using relative risks adjusted for multiple factors). Men who smoked one cigarette per day had 46% of the excess relative risk for smoking 20 cigarettes per day (53% using relative risks adjusted for multiple factors), and women had 31% of the excess risk (38% using relative risks adjusted for multiple factors). For stroke, the pooled relative risks for men were 1.25 and 1.64 for smoking one or 20 cigarettes per day (1.30 and 1.56 using relative risks adjusted for multiple factors). In women, the pooled relative risks were 1.31 and 2.16 for smoking one or 20 cigarettes per day (1.46 and 2.42 using relative risks adjusted for multiple factors). The excess risk for stroke associated with one cigarette per day (in relation to 20 cigarettes per day) was 41% for men and 34% for women (or 64% and 36% using relative risks adjusted for multiple factors). Relative risks were generally higher among women than men. Conclusions Smoking only about one cigarette per day carries a risk of developing coronary heart disease and stroke much greater than expected: around half that for people who smoke 20 per day. No safe level of smoking exists for cardiovascular disease. Smokers should aim to quit instead of cutting down to significantly reduce their risk of these two common major disorders. PMID:29367388

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.

Maternal Use of Corporal Punishment for 3-year-old Children and Subsequent Risk for Child Aggressive Behavior

PubMed Central

Taylor, Catherine A.; Manganello, Jennifer A.; Lee, Shawna J.; Rice, Janet C.

2016-01-01

OBJECTIVE To examine the association between maternal use of corporal punishment (CP) against their 3-year-old children and subsequent aggressive behavior among those children two years later. METHODS Respondents participated in waves 1, 3, and 5 of the Fragile Families and Child Wellbeing Study (1998–2005), a population-based longitudinal birth cohort study of children (and their parents) born in one of 20 large U.S. cities (n=2,461), with oversampling of unmarried couples. Maternal reports of CP, children’s aggressive behaviors at 3 and 5 years of age, and a host of key demographics and potential confounding factors were assessed including: child physical maltreatment, psychological maltreatment, and neglect, intimate partner aggression and violence, and maternal stress, depression, substance use, and consideration of abortion. RESULTS Multiple logistic regression analyses revealed that frequent use of CP (i.e., maternal use of spanking more than twice in the prior month) when the child was 3 years-old was associated with increased risk for higher levels of child aggression when the child was 5 years-old (adjusted odds ratio = 1.49 [CI=1.2–1.8] p<0.0001), even after simultaneously controlling for the child’s level of aggression at 3 years of age as well as all of the aforementioned confounding factors and key demographics. CONCLUSIONS Despite American Academy of Pediatrics recommendations to the contrary, most parents in the U.S. approve of and have used CP as a form of child discipline. The current findings support a growing body of evidence that even minor forms of CP, such as spanking, raise risk for increased subsequent child aggressive behavior. Importantly, these findings cannot be attributed to the possible confounding effects of a host of other maternal parenting risk factors. Increased and improved efforts to reduce the use of CP and promote the use of alternative, effective non-physical forms of child discipline among U.S. parents are warranted. PMID:20385647

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.

A long term study of pulmonary function among US refractory ceramic fibre workers

PubMed Central

LeMasters, Grace K; Hilbert, Timothy J; Levin, Linda S; Rice, Carol H; Borton, Eric K; Lockey, James E

2010-01-01

Background Cross-sectional studies have shown declines in lung function among refractory ceramic fibre (RCF) workers with increasing fibre exposure. This study followed current and former workers (n=1396) for up to 17 years and collected 5243 pulmonary function tests. Methods Cumulative fibre exposure and production years were categorised into exposure levels at five manufacturing locations. Conventional longitudinal models did not adequately partition age-related changes from other time-dependent variables. Therefore, a restricted cubic spline model was developed to account for the non-linear decline with age. Results Cumulative fibre >60 fibre-months/cc showed a significant loss in lung function at the first test. When results were examined longitudinally, cumulative exposure was confounded with age as workers with the highest cumulative exposure were generally older. A longitudinal model adjusted by age groups was implemented to control for this confounding. No consistent longitudinal loss in lung function was observed with RCF exposure. Smoking, initial weight and weight increase were significant factors. Conclusion No consistent decline was observed longitudinally with exposure to RCF, although cross-sectional and longitudinal findings were discordant. Confounding and accelerated lung function declines with ageing and the correlation of multiple time-dependent variables should be considered in order to minimise error and maximise precision. An innovative statistical methodology for these types of data is described. PMID:20798015

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.

Overview of potential procedural and participant-related confounds for neuroimaging of the resting state

PubMed Central

Duncan, Niall W.; Northoff, Georg

2013-01-01

Studies of intrinsic brain activity in the resting state have become increasingly common. A productive discussion of what analysis methods are appropriate, of the importance of physiologic correction and of the potential interpretations of results has been ongoing. However, less attention has been paid to factors other than physiologic noise that may confound resting-state experiments. These range from straightforward factors, such as ensuring that participants are all instructed in the same manner, to more obscure participant-related factors, such as body weight. We provide an overview of such potentially confounding factors, along with some suggested approaches for minimizing their impact. A particular theme that emerges from the overview is the range of systematic differences between types of study groups (e.g., between patients and controls) that may influence resting-state study results. PMID:22964258

How multiple causes combine: independence constraints on causal inference.

PubMed

Liljeholm, Mimi

2015-01-01

According to the causal power view, two core constraints-that causes occur independently (i.e., no confounding) and influence their effects independently-serve as boundary conditions for causal induction. This study investigated how violations of these constraints modulate uncertainty about the existence and strength of a causal relationship. Participants were presented with pairs of candidate causes that were either confounded or not, and that either interacted or exerted their influences independently. Consistent with the causal power view, uncertainty about the existence and strength of causal relationships was greater when causes were confounded or interacted than when unconfounded and acting independently. An elemental Bayesian causal model captured differences in uncertainty due to confounding but not those due to an interaction. Implications of distinct sources of uncertainty for the selection of contingency information and causal generalization are discussed.

Network Analysis of Rodent Transcriptomes in Spaceflight

NASA Technical Reports Server (NTRS)

Ramachandran, Maya; Fogle, Homer; Costes, Sylvain

2017-01-01

Network analysis methods leverage prior knowledge of cellular systems and the statistical and conceptual relationships between analyte measurements to determine gene connectivity. Correlation and conditional metrics are used to infer a network topology and provide a systems-level context for cellular responses. Integration across multiple experimental conditions and omics domains can reveal the regulatory mechanisms that underlie gene expression. GeneLab has assembled rich multi-omic (transcriptomics, proteomics, epigenomics, and epitranscriptomics) datasets for multiple murine tissues from the Rodent Research 1 (RR-1) experiment. RR-1 assesses the impact of 37 days of spaceflight on gene expression across a variety of tissue types, such as adrenal glands, quadriceps, gastrocnemius, tibalius anterior, extensor digitorum longus, soleus, eye, and kidney. Network analysis is particularly useful for RR-1 -omics datasets because it reinforces subtle relationships that may be overlooked in isolated analyses and subdues confounding factors. Our objective is to use network analysis to determine potential target nodes for therapeutic intervention and identify similarities with existing disease models. Multiple network algorithms are used for a higher confidence consensus.

Psychosocial Working Conditions and Cognitive Complaints among Swedish Employees

PubMed Central

Stenfors, Cecilia U. D.; Magnusson Hanson, Linda; Oxenstierna, Gabriel; Theorell, Töres; Nilsson, Lars-Göran

2013-01-01

Background Cognitive complaints involving problems with concentration, memory, decision-making and thinking are relatively common in the work force. The sensitivity of both subjective and objective cognitive functioning to common psychiatric conditions, stress levels and to cognitive load makes it plausible that psychosocial working conditions play a role in cognitive complaints. Thus, this study aimed to test the associations between psychosocial work factors and cognitive complaints in nationally representative samples of the Swedish work force. Cross-sectional (n = 9751) and prospective (n = 3644; two time points two years apart) sequential multiple regression analyses were run, adjusting for general confounders, depressive- and sleeping problems. Additional prospective analyses were run adjusting for baseline cognitive complaints. Cross-sectional results High quantitative demands, information and communication technology (ICT) demands, underqualification and conflicts were positively associated with cognitive complaints, while social support, good resources at work and overqualification were negatively associated with cognitive complaints in all models. Skill discretion and decision authority were weakly associated with cognitive complaints. Conflicts were more strongly associated with cognitive complaints in women than in men, after adjustment for general confounders. Prospective results Quantitative job demands, ICT demands and underqualification were positively associated with future cognitive complaints in all models, including when adjusted for baseline cognitive complaints. Decision authority was weakly positively associated with future cognitive complaints, only after adjustment for depressive- and sleeping problems respectively. Social support was negatively associated with future cognitive complaints after adjustment for general confounders and baseline cognitive complaints. Skill discretion and resources were negatively associated with future cognitive complaints after adjustment for general confounders. The associations between quantitative demands and future cognitive complaints were stronger in women. Discussion/Conclusions The findings indicate that psychosocial working conditions should be taken into account when considering cognitive complaints among employees. PMID:23560101

Normality of upper and lower peripheral pulse transit time of normotensive and hypertensive children.

PubMed

Foo, Jong Yong Abdiel

2007-08-01

The ankle-brachial index (ABI) is known to be indicative of sub-clinical peripheral arterial diseases that are correlated with cardiovascular disease risk factors like atherosclerosis or ischemic extremity. Due to its occluding measurement nature, this may not be appealing to less cooperative patients when multiple prolonged screening is required. A simple and non-intrusive approach termed pulse transit time ratio (PTTR) has recently shown to be potential surrogate marker for the prolonged ABI measurement. Other studies have also suggested that subjects with hypertension have stiffer arterial wall and thereby can confound transit time related parameters. Thus, it becomes important to understand the PTTR normality and difference of hypertensive children when compared to those measured from normotensive children. About 55 normotensive (39 male; aged 8.4 +/- 2.3 yr) and 4 hypertensive (4 male; aged 5-10 yr) Caucasian children were recruited from the same geographical location. A customized device was used to compute pulse transit time related measurements. Since the PTTR approach produced a delta value that was similar to that of ABI, possible inter-subject physiologic differences had limited confounding effects on the derived PTTR parameter. The obtained transit time measurements from the hypertensive children had lower pulse transit time value when compared to their normotensive counterparts. However, the statistical analysis indicated that they had insignificant PTTR difference (p > 0.01) from those seen in the normotensive children. The findings herein suggest that stiffer arterial wall may have confounding effects on the derived transit time related measurements but it is limited on the PTTR parameter. Similar to the ABI approach, PTTR may be only confounded by abnormal local changes in either of the measured peripheral arterial wall. Hence, the PTTR technique shows promise to be an ABI marker from this perspective.

Simulation of Medical Imaging Systems: Emission and Transmission Tomography

NASA Astrophysics Data System (ADS)

Harrison, Robert L.

Simulation is an important tool in medical imaging research. In patient scans the true underlying anatomy and physiology is unknown. We have no way of knowing in a given scan how various factors are confounding the data: statistical noise; biological variability; patient motion; scattered radiation, dead time, and other data contaminants. Simulation allows us to isolate a single factor of interest, for instance when researchers perform multiple simulations of the same imaging situation to determine the effect of statistical noise or biological variability. Simulations are also increasingly used as a design optimization tool for tomographic scanners. This article gives an overview of the mechanics of emission and transmission tomography simulation, reviews some of the publicly available simulation tools, and discusses trade-offs between the accuracy and efficiency of simulations.

The role of appraisal and coping style in relation with societal participation in fatigued patients with multiple sclerosis: a cross-sectional multiple mediator analysis.

PubMed

van den Akker, Lizanne Eva; Beckerman, Heleen; Collette, Emma Hubertine; Bleijenberg, Gijs; Dekker, Joost; Knoop, Hans; de Groot, Vincent

2016-10-01

To determine the relationship between appraisal and societal participation in fatigued patients with Multiple Sclerosis (MS), and whether this relation is mediated by coping styles. 265 severely-fatigued MS patients. Appraisal, a latent construct, was created from the General Self-Efficacy Scale and the helplessness and acceptance subscales of the Illness Cognition Questionnaire. Coping styles were assessed using the Coping Inventory Stressful Situations (CISS21) and societal participation was assessed using the Impact on Participation and Autonomy. A multiple mediator model was developed and tested by structural equation modeling on cross-sectional data. We corrected for confounding by disease-related factors. Mediation was determined using a product-of-coefficients approach. A significant relationship existed between appraisal and participation (β = 0.21, 95 % CI 0.04-0.39). The pathways via coping styles were not significant. In patients with severe MS-related fatigue, appraisal and societal participation show a positive relationship that is not mediated by coping styles.

Effect of intrapartum antibiotic prophylaxis against group B streptococcal infection on comparisons of rates of endometritis and urinary tract infection in multicenter surveillance.

PubMed

Dumas, Anne-Marie; Girard, Raphaëlle; Ayzac, Louis; Beaumont, Geneviève; Caillat-Vallet, Emmanuelle; Depaix, Florence; Gignoux, Chantal; Haond, Catherine; Pral, Noelle; Robert, Jacqueline; Tissot-Guerraz, Françoise; Vincent-Bouletreau, Agnès; Berland, Michel; Fabry, Jacques

2008-04-01

To establish whether antibiotic prophylaxis against group B streptococcal infection may be a confounding factor in comparisons of rates of endometritis and urinary tract infection after vaginal delivery. Prospective study. Maternity units at 48 hospitals in a regional surveillance network in France during 2001-2004. The maternity units used a common protocol to establish whether antibiotic prophylaxis was indicated. Risk factors for endometritis and urinary tract infections were evaluated using multiple logistic regression. We analyzed 49,786 vaginal deliveries. The percentage of women receiving antibiotic prophylaxis varied widely and significantly among the maternity units (range, 4.4%-26.0%; median, 15.8%; 25th percentile, 12.1%; 75th percentile, 19.0%) (P < .001, by Mantel-Haenszel chi(2) test). The incidence rate of endometritis was significantly reduced from 0.25% to 0.11% by antibiotic prophylaxis (P = .001). There was a decrease in the incidence of urinary tract infection from 0.37% to 0.32%, but it was not statistically significant (P = .251). A reduction in the incidence of endometritis was observed when intrapartum antibiotic prophylaxis against group B streptococcal infection was used. However, the proportion of women considered to be at risk of infection varied widely among institutions. Comparisons of rates of endometritis among maternity units, but not urinary tract infection rates, should take into account antibiotic prophylaxis as a significant confounding factor.

[Impact analysis of shuxuetong injection on abnormal changes of ALT based on generalized boosted models propensity score weighting].

PubMed

Yang, Wei; Yi, Dan-Hui; Xie, Yan-Ming; Yang, Wei; Dai, Yi; Zhi, Ying-Jie; Zhuang, Yan; Yang, Hu

2013-09-01

To estimate treatment effects of Shuxuetong injection on abnormal changes on ALT index, that is, to explore whether the Shuxuetong injection harms liver function in clinical settings and to provide clinical guidance for its safe application. Clinical information of traditional Chinese medicine (TCM) injections is gathered from hospital information system (HIS) of eighteen general hospitals. This is a retrospective cohort study, using abnormal changes in ALT index as an outcome. A large number of confounding biases are taken into account through the generalized boosted models (GBM) and multiple logistic regression model (MLRM) to estimate the treatment effects of Shuxuetong injections on abnormal changes in ALT index and to explore possible influencing factors. The advantages and process of application of GBM has been demonstrated with examples which eliminate the biases from most confounding variables between groups. This serves to modify the estimation of treatment effects of Shuxuetong injection on ALT index making the results more reliable. Based on large scale clinical observational data from HIS database, significant effects of Shuxuetong injection on abnormal changes in ALT have not been found.

Familial confounding of the association between maternal smoking during pregnancy and offspring substance use and problems.

PubMed

D'Onofrio, Brian M; Rickert, Martin E; Langström, Niklas; Donahue, Kelly L; Coyne, Claire A; Larsson, Henrik; Ellingson, Jarrod M; Van Hulle, Carol A; Iliadou, Anastasia N; Rathouz, Paul J; Lahey, Benjamin B; Lichtenstein, Paul

2012-11-01

Previous epidemiological, animal, and human cognitive neuroscience research suggests that maternal smoking during pregnancy (SDP) causes increased risk of substance use/problems in offspring. To determine the extent to which the association between SDP and offspring substance use/problems depends on confounded familial background factors by using a quasi-experimental design. We used 2 separate samples from the United States and Sweden. The analyses prospectively predicted multiple indices of substance use and problems while controlling for statistical covariates and comparing differentially exposed siblings to minimize confounding. Offspring of a representative sample of women in the United States (sample 1) and the total Swedish population born during the period from January 1, 1983, to December 31, 1995 (sample 2). Adolescent offspring of the women in the National Longitudinal Survey of Youth 1979 (n = 6904) and all offspring born in Sweden during the 13-year period (n = 1,187,360). Self-reported adolescent alcohol, cigarette, and marijuana use and early onset (before 14 years of age) of each substance (sample 1) and substance-related convictions and hospitalizations for an alcohol- or other drug-related problem (sample 2). The same pattern emerged for each index of substance use/problems across the 2 samples. At the population level, maternal SDP predicted every measure of offspring substance use/problems in both samples, ranging from adolescent alcohol use (hazard ratio [HR](moderate), 1.32 [95% CI, 1.22-1.43]; HR(high), 1.33 [1.17-1.53]) to a narcotics-related conviction (HR(moderate), 2.23 [2.14-2.31]; HR(high), 2.97 [2.86-3.09]). When comparing differentially exposed siblings to minimize genetic and environmental confounds, however, the association between SDP and each measure of substance use/problems was minimal and not statistically significant. The association between maternal SDP and offspring substance use/problems is likely due to familial background factors, not a causal influence, because siblings have similar rates of substance use and problems regardless of their specific exposure to SDP.

Syphilis may be a confounding factor, not a causative agent, in syphilitic ALS.

PubMed

Tuk, Bert

2016-01-01

Based upon a review of published clinical observations regarding syphilitic amyotrophic lateral sclerosis (ALS), I hypothesize that syphilis is actually a confounding factor, not a causative factor, in syphilitic ALS. Moreover, I propose that the successful treatment of ALS symptoms in patients with syphilitic ALS using penicillin G and hydrocortisone is an indirect consequence of the treatment regimen and is not due to the treatment of syphilis. Specifically, I propose that the observed effect is due to the various pharmacological activities of penicillin G ( e.g ., a GABA receptor antagonist) and/or the multifaceted pharmacological activity of hydrocortisone. The notion that syphilis may be a confounding factor in syphilitic ALS is highly relevant, as it suggests that treating ALS patients with penicillin G and hydrocortisone-regardless of whether they present with syphilitic ALS or non-syphilitic ALS-may be effective at treating this rapidly progressive, highly devastating disease.

Parental History of Type 2 Diabetes in Patients with Nonaffective Psychosis

PubMed Central

Fernandez-Egea, Emilio; Miller, Brian; Bernardo, Miguel; Donner, Thomas; Kirkpatrick, Brian

2009-01-01

Introduction We attempted to replicate two previous studies which found an increased risk of diabetes in the relatives of schizophrenia probands. Methods N=34 patients with newly-diagnosed nonaffective psychosis and N=52 non-psychiatric controls were interviewed for parental history of Type 2 diabetes. Results In a logistic regression model that included multiple potential confounders, psychosis was a significant predictor of Type 2 diabetes in either parent (p<0.04). Discussion We found an increased prevalence of Type 2 diabetes in the parents of nonaffective psychosis subjects. This association may be due to shared environmental or genetic risk factors, or both. PMID:18031995

Understanding Confounding Effects in Linguistic Coordination: An Information-Theoretic Approach

PubMed Central

Gao, Shuyang; Ver Steeg, Greg; Galstyan, Aram

2015-01-01

We suggest an information-theoretic approach for measuring stylistic coordination in dialogues. The proposed measure has a simple predictive interpretation and can account for various confounding factors through proper conditioning. We revisit some of the previous studies that reported strong signatures of stylistic accommodation, and find that a significant part of the observed coordination can be attributed to a simple confounding effect—length coordination. Specifically, longer utterances tend to be followed by longer responses, which gives rise to spurious correlations in the other stylistic features. We propose a test to distinguish correlations in length due to contextual factors (topic of conversation, user verbosity, etc.) and turn-by-turn coordination. We also suggest a test to identify whether stylistic coordination persists even after accounting for length coordination and contextual factors. PMID:26115446

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.

Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River Through Hells Canyon

PubMed Central

Braatne, Jeffrey H.; Goater, Lori A.; Blair, Charles L.

2007-01-01

River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1) upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing or differently regulated river(s). Temporal comparisons consider (4) pre- versus post-dam, or (5) sequential post-dam conditions. However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre- versus post-dam comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies. PMID:18043964

Shared processing in multiple object tracking and visual working memory in the absence of response order and task order confounds

PubMed Central

Howe, Piers D. L.

2017-01-01

To understand how the visual system represents multiple moving objects and how those representations contribute to tracking, it is essential that we understand how the processes of attention and working memory interact. In the work described here we present an investigation of that interaction via a series of tracking and working memory dual-task experiments. Previously, it has been argued that tracking is resistant to disruption by a concurrent working memory task and that any apparent disruption is in fact due to observers making a response to the working memory task, rather than due to competition for shared resources. Contrary to this, in our experiments we find that when task order and response order confounds are avoided, all participants show a similar decrease in both tracking and working memory performance. However, if task and response order confounds are not adequately controlled for we find substantial individual differences, which could explain the previous conflicting reports on this topic. Our results provide clear evidence that tracking and working memory tasks share processing resources. PMID:28410383

Shared processing in multiple object tracking and visual working memory in the absence of response order and task order confounds.

PubMed

Lapierre, Mark D; Cropper, Simon J; Howe, Piers D L

2017-01-01

To understand how the visual system represents multiple moving objects and how those representations contribute to tracking, it is essential that we understand how the processes of attention and working memory interact. In the work described here we present an investigation of that interaction via a series of tracking and working memory dual-task experiments. Previously, it has been argued that tracking is resistant to disruption by a concurrent working memory task and that any apparent disruption is in fact due to observers making a response to the working memory task, rather than due to competition for shared resources. Contrary to this, in our experiments we find that when task order and response order confounds are avoided, all participants show a similar decrease in both tracking and working memory performance. However, if task and response order confounds are not adequately controlled for we find substantial individual differences, which could explain the previous conflicting reports on this topic. Our results provide clear evidence that tracking and working memory tasks share processing resources.

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.

Work-Home Interference, Perceived Total Workload, and the Risk of Future Sickness Absence Due to Stress-Related Mental Diagnoses Among Women and Men: a Prospective Twin Study.

PubMed

Svedberg, Pia; Mather, Lisa; Bergström, Gunnar; Lindfors, Petra; Blom, Victoria

2018-02-01

Work-home interference has been proposed as an important explanation for sickness absence (SA). Previous studies show mixed results, have not accounted for familial factors (genetics and shared everyday environment), or investigated diagnosis specific SA. The aim was to study whether work-home interference and perceived total workload predict SA due to stress-related mental diagnoses, or SA due to other mental diagnoses, among women and men, when adjusting for various confounders and familial factors. This study included 11,916 twins, 19-47 years (49% women). Data on work-to-home and home-to-work conflicts, perceived total workload, and relevant confounders were derived from a 2005 survey, and national register data on SA spells until 2013 were obtained. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Discordant twin pair design was applied to adjust for familial factors. Each one unit increase in work-to-home and home-to-work conflicts, and perceived total workload was associated with higher odds for SA due to stress-related mental diagnoses and to SA due to other mental diagnoses among women, when adjusting for sociodemographic factors (ORs 1.15-1.31). Including health or familial factors, no associations remained. For men, each one unit increase in work-to-home conflicts was associated with higher odds for SA due to stress-related diagnoses (ORs 1.23-1.35), independently of confounders. Work-to-home conflict was independently associated with future SA due to stress-related diagnoses among men only. Health- and work-related factors seem to be important confounders when researching work-home interference, perceived total workload, and SA. Not including such confounders involves risking drawing incorrect conclusions. Further studies are needed to confirm sex differences and whether genetic factors are important for the associations studied.

A Pilot Study of Reasons and Risk Factors for "No-Shows" in a Pediatric Neurology Clinic.

PubMed

Guzek, Lindsay M; Fadel, William F; Golomb, Meredith R

2015-09-01

Missed clinic appointments lead to decreased patient access, worse patient outcomes, and increased healthcare costs. The goal of this pilot study was to identify reasons for and risk factors associated with missed pediatric neurology outpatient appointments ("no-shows"). This was a prospective cohort study of patients scheduled for 1 week of clinic. Data on patient clinical and demographic information were collected by record review; data on reasons for missed appointments were collected by phone interviews. Univariate and multivariate analyses were conducted using chi-square tests and multiple logistic regression to assess risk factors for missed appointments. Fifty-nine (25%) of 236 scheduled patients were no-shows. Scheduling conflicts (25.9%) and forgetting (20.4%) were the most common reasons for missed appointments. When controlling for confounding factors in the logistic regression, Medicaid (odds ratio 2.36), distance from clinic, and time since appointment was scheduled were associated with missed appointments. Further work in this area is needed. © The Author(s) 2014.

Tehran Survey of Potential Risk Factors for Multiple Births.

PubMed

Omani Samani, Reza; Almasi-Hashiani, Amir; Vesali, Samira; Shokri, Fatemeh; Cheraghi, Rezvaneh; Torkestani, Farahnaz; Sepidarkish, Mahdi

2017-10-01

The multiple pregnancy incidence is increasing worldwide. This increased incidence is concerning to the health care system. This study aims to determine the frequency of multiple pregnancy and identify factors that affect this frequency in Tehran, Iran. This cross-sectional study included 5170 mothers in labor between July 6-21, 2015 from 103 hospitals with Obstetrics and Gynecology Wards. The questionnaire used in this study consisted of five parts: demographic characteristics; information related to pregnancy; information related to the infant; information regarding the multiple pregnancy; and information associated with infertility. We recruited 103 trained midwives to collect data related to the questionnaire from eligible participants through an interview and medical records review. Frequencies and odds ratios (OR) for the association between multiple pregnancy and the selected characteristics (maternal age, economic status, history of multiple pregnancy in first-degree relatives, and reproductive history) were computed by multiple logistic regression. Stata software, version 13 (Stata Corp, College Station, TX, USA) was used for all statistical analyses. Multiple pregnancy had a prevalence of 1.48% [95% confidence interval (CI): 1.19-1.85]. After controlling for confounding variables, we observed a significant association between frequency of multiple pregnancy and mother's age (OR=1.04, 95% CI: 1.001-1.09, P=0.044), assisted reproductive technique (ART, OR=6.11, 95% CI: 1.7- 21.97, P=0.006), and history of multiple pregnancy in the mother's family (OR=5.49, 95% CI: 3.55-9.93, P=0.001). The frequency of multiple pregnancy approximated results reported in previous studies in Iran. Based on the results, we observed significantly greater frequency of multiple pregnancy in older women, those with a history of ART, and a history of multiple pregnancy in the mother's family compared to the other variables. Copyright© by Royan Institute. All rights reserved.

Selection of higher order regression models in the analysis of multi-factorial transcription data.

PubMed

Prazeres da Costa, Olivia; Hoffman, Arthur; Rey, Johannes W; Mansmann, Ulrich; Buch, Thorsten; Tresch, Achim

2014-01-01

Many studies examine gene expression data that has been obtained under the influence of multiple factors, such as genetic background, environmental conditions, or exposure to diseases. The interplay of multiple factors may lead to effect modification and confounding. Higher order linear regression models can account for these effects. We present a new methodology for linear model selection and apply it to microarray data of bone marrow-derived macrophages. This experiment investigates the influence of three variable factors: the genetic background of the mice from which the macrophages were obtained, Yersinia enterocolitica infection (two strains, and a mock control), and treatment/non-treatment with interferon-γ. We set up four different linear regression models in a hierarchical order. We introduce the eruption plot as a new practical tool for model selection complementary to global testing. It visually compares the size and significance of effect estimates between two nested models. Using this methodology we were able to select the most appropriate model by keeping only relevant factors showing additional explanatory power. Application to experimental data allowed us to qualify the interaction of factors as either neutral (no interaction), alleviating (co-occurring effects are weaker than expected from the single effects), or aggravating (stronger than expected). We find a biologically meaningful gene cluster of putative C2TA target genes that appear to be co-regulated with MHC class II genes. We introduced the eruption plot as a tool for visual model comparison to identify relevant higher order interactions in the analysis of expression data obtained under the influence of multiple factors. We conclude that model selection in higher order linear regression models should generally be performed for the analysis of multi-factorial microarray data.

A review of factors explaining variability in fentanyl pharmacokinetics; focus on implications for cancer patients

PubMed Central

Zandvliet, Maarten L.; Koolen, Stijn L. W.; Mathijssen, Ron H. J.; van der Rijt, Carin C. D.

2016-01-01

Fentanyl is a strong opioid that is available for various administration routes, and which is widely used to treat cancer‐related pain. Many factors influence the fentanyl pharmacokinetics leading to a wide inter‐ and intrapatient variability. This systematic review summarizes multiple studied factors that potentially influence fentanyl pharmacokinetics with a focus on implications for cancer patients. The use of CYP3A4 inhibitors and inducers, impaired liver function, and heating of the patch potentially influence fentanyl pharmacokinetics in a clinically relevant way. In elderly patients, current data suggest that we should carefully dose fentanyl due to alterations in absorption and metabolism. The influence of BMI and gender on fentanyl pharmacokinetics is questionable, most probably due to a large heterogeneity in the published studies. Pharmacogenetics, e.g. the CYP3A5*3 gene polymorphism, may influence fentanyl pharmacokinetics as well, although further study is warranted. Several other factors have been studied but did not show significant and clinically relevant effects on fentanyl pharmacokinetics. Unfortunately, most of the published papers that studied factors influencing fentanyl pharmacokinetics describe healthy volunteers instead of cancer patients. Results from the studies in volunteers may not be simply extrapolated to cancer patients because of multiple confounding factors. To handle fentanyl treatment in a population of cancer patients, it is essential that physicians recognize factors that influence fentanyl pharmacokinetics, thereby preventing potential side‐effects and increasing its efficacy. PMID:27619152

Commentary: How can family-based quasi-experimental designs and national registers be used to address confounding in risk factor studies of psychopathology? A reflection on Obel et al. (2016).

PubMed

Larsson, Henrik

2016-04-01

Standard observational studies have reported a robust correlation between maternal smoking during pregnancy and risk of ADHD in offspring. In the accompanying article, Obel et al. used sibling-comparisons to explore the extent to which unmeasured familial confounding explains this association. This commentary highlights three important implications of the study. At a general level, Obel et al. illustrates how (1) family-based quasi-experimental designs and (2) national registers can be used to address confounding in risk factor studies of psychopathology. At a more specific level, the study suggests that maternal smoking during pregnancy is probably not a causal risk factor for ADHD. © 2016 Association for Child and Adolescent Mental Health.

Recruitment factors which affect the outcome of a seasonal allergic rhinitis trial.

PubMed

Sharma, Shilpy; Vasnani, Raj; De Tineo, Marcella; Du, Gaixin; Pinto, Jayant M; Baroody, Fuad M; Naclerio, Robert M

2011-01-01

Although intranasal corticosteroids (INSs) are the first-line treatment for seasonal allergic rhinitis (SAR), some patients do not respond adequately, reflecting biological heterogeneity or confounding conditions. The objective of this study was to determine what recruitment factors identify SAR subjects who will be unresponsive to mometasone furoate (MF). We performed a 2-week, double-blind, placebo-controlled, parallel study on 40 subjects with SAR. Each subject underwent a decongestant test using oxymetazoline. Baseline nasal symptoms, nasal peak inspiratory flow (NPIF) and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scores were recorded. Next, subjects were randomized to either 200 μg of MF or placebo. Symptom diaries and NPIF measurements were completed twice daily. After 2 weeks, subjects repeated the RQLQ and the global assessment of symptoms. There was a significant reduction in symptoms in the MF group compared with placebo (p ≤ 0.05) in patients with baseline total symptom scores of ≥6. Multivariate analysis showed that treatment (MF versus placebo; p = 0.049) and amount of decongestion (percent change in NPIF after oxymetazoline; p = 0.008) predicted the improvement in total nasal symptoms. In clinical trials, SAR subjects must report multiple symptoms to be responsive to treatment with INSs. Our results also support the use of the decongestant test for choice of appropriate study volunteers, both to ensure participation of potentially responsive subjects and to eliminate those with confounding issues.

Rainfall and temperatures changes have confounding impacts on Phytophthora cinnamomi occurrence risk in the southwestern USA under climate change scenarios.

PubMed

Thompson, Sally E; Levin, Simon; Rodriguez-Iturbe, Ignacio

2014-04-01

Global change will simultaneously impact many aspects of climate, with the potential to exacerbate the risks posed by plant pathogens to agriculture and the natural environment; yet, most studies that explore climate impacts on plant pathogen ranges consider individual climatic factors separately. In this study, we adopt a stochastic modeling approach to address multiple pathways by which climate can constrain the range of the generalist plant pathogen Phytophthora cinnamomi (Pc): through changing winter soil temperatures affecting pathogen survival; spring soil temperatures and thus pathogen metabolic rates; and changing spring soil moisture conditions and thus pathogen growth rates through host root systems. We apply this model to the southwestern USA for contemporary and plausible future climate scenarios and evaluate the changes in the potential range of Pc. The results indicate that the plausible range of this pathogen in the southwestern USA extends over approximately 200,000 km(2) under contemporary conditions. While warming temperatures as projected by the IPCC A2 and B1 emissions scenarios greatly expand the range over which the pathogen can survive winter, projected reductions in spring rainfall reduce its feasible habitat, leading to spatially complex patterns of changing risk. The study demonstrates that temperature and rainfall changes associated with possible climate futures in the southwestern USA have confounding impacts on the range of Pc, suggesting that projections of future pathogen dynamics and ranges should account for multiple pathways of climate-pathogen interaction. © 2014 John Wiley & Sons Ltd.

Impact of concomitant dexamethasone dosing schedule on bortezomib-induced peripheral neuropathy in multiple myeloma.

PubMed

Kumar, Shaji K; Laubach, Jacob P; Giove, Thomas J; Quick, Maureen; Neuwirth, Rachel; Yung, Godwin; Rajkumar, S Vincent; Richardson, Paul G

2017-09-01

Peripheral neuropathy (PN) is the most troublesome adverse event associated with the proteasome inhibitor bortezomib. Studies suggest an inflammatory aetiology for bortezomib-induced PN (BiPN) and it has been hypothesized that reducing inflammation with concomitant dexamethasone may reduce BiPN incidence and/or severity. We retrospectively analysed PN rates from 32 studies (2697 patients with previously untreated multiple myeloma) incorporating bortezomib and differing dexamethasone schedules: partnered dosing (days of and after bortezomib), weekly dosing, and other dosing schedules (e.g. days 1-4, 8-11). Pooled overall PN rates were 45·5%, 63·9%, and 47·5%, respectively, with 5·3%, 11·0%, and 9·6% grade ≥3. Adjusting for potential confounders (age, gender, presence of thalidomide, bortezomib treatment duration), PN rates in patients on partnered dosing schedules appeared lower than in patients on weekly or other dosing schedules. Analyses conducted using patient-level data suggest that cumulative dexamethasone dose, a potential confounding factor, is unlikely to have influenced the analyses. Findings were similar in a separate pooled analysis excluding data from regimens incorporating thalidomide, when pooled overall PN rates were 50·1%, 63·9%, and 48·3%, respectively, with 4·2%, 11·0%, and 8·6% grade ≥3. These findings suggest that partnered dexamethasone dosing may result in less severe BiPN compared with alternative dexamethasone dosing schedules. © 2017 John Wiley & Sons Ltd.

A spatial analysis of social and economic determinants of tuberculosis in Brazil.

PubMed

Harling, Guy; Castro, Marcia C

2014-01-01

We investigated the spatial distribution, and social and economic correlates, of tuberculosis in Brazil between 2002 and 2009 using municipality-level age/sex-standardized tuberculosis notification data. Rates were very strongly spatially autocorrelated, being notably high in urban areas on the eastern seaboard and in the west of the country. Non-spatial ecological regression analyses found higher rates associated with urbanicity, population density, poor economic conditions, household crowding, non-white population and worse health and healthcare indicators. These associations remained in spatial conditional autoregressive models, although the effect of poverty appeared partially confounded by urbanicity, race and spatial autocorrelation, and partially mediated by household crowding. Our analysis highlights both the multiple relationships between socioeconomic factors and tuberculosis in Brazil, and the importance of accounting for spatial factors in analysing socioeconomic determinants of tuberculosis. © 2013 Published by Elsevier Ltd.

Deriving field-based species sensitivity distributions (f-SSDs) from stacked species distribution models (S-SDMs).

PubMed

Schipper, Aafke M; Posthuma, Leo; de Zwart, Dick; Huijbregts, Mark A J

2014-12-16

Quantitative relationships between species richness and single environmental factors, also called species sensitivity distributions (SSDs), are helpful to understand and predict biodiversity patterns, identify environmental management options and set environmental quality standards. However, species richness is typically dependent on a variety of environmental factors, implying that it is not straightforward to quantify SSDs from field monitoring data. Here, we present a novel and flexible approach to solve this, based on the method of stacked species distribution modeling. First, a species distribution model (SDM) is established for each species, describing its probability of occurrence in relation to multiple environmental factors. Next, the predictions of the SDMs are stacked along the gradient of each environmental factor with the remaining environmental factors at fixed levels. By varying those fixed levels, our approach can be used to investigate how field-based SSDs for a given environmental factor change in relation to changing confounding influences, including for example optimal, typical, or extreme environmental conditions. This provides an asset in the evaluation of potential management measures to reach good ecological status.

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.

Comparison of Statistical Approaches Dealing with Time-dependent Confounding in Drug Effectiveness Studies

PubMed Central

Karim, Mohammad Ehsanul; Petkau, John; Gustafson, Paul; Platt, Robert W.; Tremlett, Helen

2017-01-01

In longitudinal studies, if the time-dependent covariates are affected by the past treatment, time-dependent confounding may be present. For a time-to-event response, marginal structural Cox models (MSCMs) are frequently used to deal with such confounding. To avoid some of the problems of fitting MSCM, the sequential Cox approach has been suggested as an alternative. Although the estimation mechanisms are different, both approaches claim to estimate the causal effect of treatment by appropriately adjusting for time-dependent confounding. We carry out simulation studies to assess the suitability of the sequential Cox approach for analyzing time-to-event data in the presence of a time-dependent covariate that may or may not be a time-dependent confounder. Results from these simulations revealed that the sequential Cox approach is not as effective as MSCM in addressing the time-dependent confounding. The sequential Cox approach was also found to be inadequate in the presence of a time-dependent covariate. We propose a modified version of the sequential Cox approach that correctly estimates the treatment effect in both of the above scenarios. All approaches are applied to investigate the impact of beta-interferon treatment in delaying disability progression in the British Columbia Multiple Sclerosis cohort (1995 – 2008). PMID:27659168

Comparison of statistical approaches dealing with time-dependent confounding in drug effectiveness studies.

PubMed

Karim, Mohammad Ehsanul; Petkau, John; Gustafson, Paul; Platt, Robert W; Tremlett, Helen

2018-06-01

In longitudinal studies, if the time-dependent covariates are affected by the past treatment, time-dependent confounding may be present. For a time-to-event response, marginal structural Cox models are frequently used to deal with such confounding. To avoid some of the problems of fitting marginal structural Cox model, the sequential Cox approach has been suggested as an alternative. Although the estimation mechanisms are different, both approaches claim to estimate the causal effect of treatment by appropriately adjusting for time-dependent confounding. We carry out simulation studies to assess the suitability of the sequential Cox approach for analyzing time-to-event data in the presence of a time-dependent covariate that may or may not be a time-dependent confounder. Results from these simulations revealed that the sequential Cox approach is not as effective as marginal structural Cox model in addressing the time-dependent confounding. The sequential Cox approach was also found to be inadequate in the presence of a time-dependent covariate. We propose a modified version of the sequential Cox approach that correctly estimates the treatment effect in both of the above scenarios. All approaches are applied to investigate the impact of beta-interferon treatment in delaying disability progression in the British Columbia Multiple Sclerosis cohort (1995-2008).

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.

Prevalent involvement of thenar motor fibres in vineyard workers with carpal tunnel syndrome.

PubMed

Mondelli, M; Baldasseroni, A; Aretini, A; Ginanneschi, F; Padua, L

2010-08-01

Carpal tunnel syndrome (CTS) has a high prevalence in agricultural workers, especially those engaged in vineyards. We postulated that vineyard CTS was electrophysiologically different from CTS of other subjects. We performed a retrospective cross-sectional electrophysiological study of two cohorts of consecutive patients with CTS, the first consisting of vineyard workers and the second, of other unselected types of workers, housewives and pensioners. Thirty-three vineyard workers (mean age 46.8years, 42% women) and 205 patients with other occupations (mean age 53.7years; 66% women) were enrolled. All patients underwent sensory and motor neurography of the median and ulnar nerves. Differences in demographic and electrophysiological findings between groups were calculated and multiple linear regression analysis was performed to eliminate the influence of potential confounding factors (age, sex, BMI, clinical severity of CTS) on the results of univariate difference analysis. Univariate analysis showed that DML was longer and compound muscle action potential amplitude of the median nerve, recorded from the abductor pollicis brevis muscle, was smaller in vineyard workers than in the other CTS patients. These differences remained significant after adjusting the results for confounding factors. The vineyard workers showed a different pattern of CTS than the other patients: thenar motor fibres were more affected, presumably due to chronic compression on the thenar branch. This suggests an association between "common" CTS and thenar mononeuropathy. Occupational physiologists should clarify the mechanisms of neuromuscular engagement in particular jobs and ergonomists design suitable working tools, because many "individual" risk factors are difficult to change, but workplace-related risk factors can be modified. Copyright 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Does consideration of larger study areas yield more accurate estimates of air pollution health effects? An illustration of the bias-variance trade-off in air pollution epidemiology.

PubMed

Pedersen, Marie; Siroux, Valérie; Pin, Isabelle; Charles, Marie Aline; Forhan, Anne; Hulin, Agnés; Galineau, Julien; Lepeule, Johanna; Giorgis-Allemand, Lise; Sunyer, Jordi; Annesi-Maesano, Isabella; Slama, Rémy

2013-10-01

Spatially-resolved air pollution models can be developed in large areas. The resulting increased exposure contrasts and population size offer opportunities to better characterize the effect of atmospheric pollutants on respiratory health. However the heterogeneity of these areas may also enhance the potential for confounding. We aimed to discuss some analytical approaches to handle this trade-off. We modeled NO2 and PM10 concentrations at the home addresses of 1082 pregnant mothers from EDEN cohort living in and around urban areas, using ADMS dispersion model. Simulations were performed to identify the best strategy to limit confounding by unmeasured factors varying with area type. We examined the relation between modeled concentrations and respiratory health in infants using regression models with and without adjustment or interaction terms with area type. Simulations indicated that adjustment for area limited the bias due to unmeasured confounders varying with area at the costs of a slight decrease in statistical power. In our cohort, rural and urban areas differed for air pollution levels and for many factors associated with respiratory health and exposure. Area tended to modify effect measures of air pollution on respiratory health. Increasing the size of the study area also increases the potential for residual confounding. Our simulations suggest that adjusting for type of area is a good option to limit residual confounding due to area-associated factors without restricting the area size. Other statistical approaches developed in the field of spatial epidemiology are an alternative to control for poorly-measured spatially-varying confounders. © 2013 Elsevier Ltd. All rights reserved.

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.

Association Between Cardiovascular Risk Factors and Carpal Tunnel Syndrome in Pooled Occupational Cohorts.

PubMed

Hegmann, Kurt T; Thiese, Matthew Steven; Kapellusch, Jay; Merryweather, Andrew S; Bao, Stephen; Silverstein, Barbara; Wood, Eric M; Kendall, Richard; Wertsch, Jacqueline; Foster, James; Garg, Arun; Drury, David L

2016-01-01

The aim of the study was to ascertain if cardiovascular (CVD) risk factors are carpal tunnel syndrome (CTS) risk factors. Analysis of pooled baseline data from two large prospective cohort studies (n = 1824) assessed the relationships between a modified Framingham Heart Study CVD risk score both CTS and abnormal nerve conduction study prevalence. Quantified job exposures, personal and psychosocial confounders were statistically controlled. Odds ratio and 95% confidence intervals were calculated for individual risk scores. There was a strong relationship between CVD risk score and both CTS and abnormal nerve conduction study after adjustment for confounders, with odds ratios as high as 4.16 and 7.35, respectively. Dose responses were also observed. In this workplace population, there is a strong association between CVD risk scores and both CTS and abnormal nerve conduction study that persisted after controlling for confounders. These data suggest a potentially modifiable disease mechanism.

If it is published in the peer-reviewed literature, it must be true?

PubMed

Wagner, Louis K

2014-10-01

Epidemiological research correlating cancer rates in a population of patients with radiation doses from medical X-rays is fraught with confounding factors that obfuscate the likelihood that any positive relationship is causal. This is a review of four studies involving some of those confounding factors. Comparisons of findings with other studies not encumbered by similar confounding factors can enhance assertions of causation between medical X-rays and cancer rates. Even so, such assertions rest significantly on opinions of researchers regarding the degree of consistency between findings among various studies. The question as to what degree any findings truly represent cause and effect will likely still meet with controversy. The importance of these findings to medicine should therefore not lie in any controversy regarding causation, but in what the findings potentially mean with regard to benefit and risk for patients and the professional practice of medicine.

The Combined Influence of Air Pollution and Home Learning Environment on Early Cognitive Skills in Children

PubMed Central

Stingone, Jeanette A.

2017-01-01

Cognitive skills are one component of school readiness that reflect a child’s neurodevelopment and are influenced by environmental and social factors. Most studies assess the impact of these factors individually, without taking into consideration the complex interactions of multiple factors. The objective of this study was to examine the joint association of markers of environmental pollution and of social factors on early cognitive skills in an urban cohort of children. For this, we chose isophorone in ambient air as a marker of industrial air pollution. Low quality home learning environments was chosen as a marker of the social factors contributing to cognitive development. Using a subpopulation from the Early Childhood Longitudinal Study, Birth Cohort (N = 4050), isophorone exposure was assigned using the 2002 National Air Toxics Assessment. Home learning environment was assessed with a modified version of the Home Observation for Measurement of the Environment (HOME) Inventory, and standardized math assessment scores were used as a measure of early cognitive skills. Multiple linear regression was used to estimate the effect of both exposures on math scores. After adjustment for confounders, children living in areas with ambient isophorone in the upper quintile of exposure (>0.49 ng/m3) had math scores that were 1.63 points lower than their less exposed peers [95% CI: −2.91, −0.34], and children with lower HOME scores (at or below 9 out of 12) had math scores that were 1.20 points lower than children with better HOME scores [95% CI: −2.30, −0.10]. In adjusted models accounting for identified confounders and both exposures of interest, both high isophorone exposure and low HOME score remained independently associated with math scores [−1.48, 95% CI: −2.79, −0.18; −1.05, 95% CI: −2.15, 0.05, respectively]. There was no statistical evidence of interaction between the two exposures, although children with both higher isophorone exposure and a low HOME score had a decrement in math scale score beyond the additive effect of each exposure. This was primarily observed among male children. These findings suggest that aspects of both the physical and social environments are independently associated with children’s early cognitive skills. Future research aiming to improve children’s early cognitive skills and subsequent school readiness should address both domains. PMID:29072589

The Combined Influence of Air Pollution and Home Learning Environment on Early Cognitive Skills in Children.

PubMed

Lett, Lanair A; Stingone, Jeanette A; Claudio, Luz

2017-10-26

Cognitive skills are one component of school readiness that reflect a child's neurodevelopment and are influenced by environmental and social factors. Most studies assess the impact of these factors individually, without taking into consideration the complex interactions of multiple factors. The objective of this study was to examine the joint association of markers of environmental pollution and of social factors on early cognitive skills in an urban cohort of children. For this, we chose isophorone in ambient air as a marker of industrial air pollution. Low quality home learning environments was chosen as a marker of the social factors contributing to cognitive development. Using a subpopulation from the Early Childhood Longitudinal Study, Birth Cohort (N = 4050), isophorone exposure was assigned using the 2002 National Air Toxics Assessment. Home learning environment was assessed with a modified version of the Home Observation for Measurement of the Environment (HOME) Inventory, and standardized math assessment scores were used as a measure of early cognitive skills. Multiple linear regression was used to estimate the effect of both exposures on math scores. After adjustment for confounders, children living in areas with ambient isophorone in the upper quintile of exposure (>0.49 ng/m³) had math scores that were 1.63 points lower than their less exposed peers [95% CI: -2.91, -0.34], and children with lower HOME scores (at or below 9 out of 12) had math scores that were 1.20 points lower than children with better HOME scores [95% CI: -2.30, -0.10]. In adjusted models accounting for identified confounders and both exposures of interest, both high isophorone exposure and low HOME score remained independently associated with math scores [-1.48, 95% CI: -2.79, -0.18; -1.05, 95% CI: -2.15, 0.05, respectively]. There was no statistical evidence of interaction between the two exposures, although children with both higher isophorone exposure and a low HOME score had a decrement in math scale score beyond the additive effect of each exposure. This was primarily observed among male children. These findings suggest that aspects of both the physical and social environments are independently associated with children's early cognitive skills. Future research aiming to improve children's early cognitive skills and subsequent school readiness should address both domains.

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.

Marijuana Use in Pregnancy: Concerns in an Evolving Era.

PubMed

Foeller, Megan E; Lyell, Deirdre J

2017-05-01

Marijuana is the most commonly used illicit drug in pregnancy, and the prevalence of use during pregnancy is increasing in the United States. Although much of the existing research investigating marijuana use in pregnancy is limited by study design and confounding factors, a growing accumulation of data suggests adverse outcomes. Studies have identified associations with decreased birth weight, increased spontaneous preterm birth, and impaired neurodevelopment among children and adults with in utero exposure. Moderate concentrations of marijuana have also been identified in breast milk. Due to these findings, multiple professional societies have issued clear statements against marijuana use during pregnancy and lactation. © 2017 by the American College of Nurse-Midwives.

What's in a name? Y chromosomes, surnames and the genetic genealogy revolution.

PubMed

King, Turi E; Jobling, Mark A

2009-08-01

Heritable surnames are highly diverse cultural markers of coancestry in human populations. A patrilineal surname is inherited in the same way as the non-recombining region of the Y chromosome and there should, therefore, be a correlation between the two. Studies of Y haplotypes within surnames, mostly of the British Isles, reveal high levels of coancestry among surname cohorts and the influence of confounding factors, including multiple founders for names, non-paternities and genetic drift. Combining molecular genetics and surname analysis illuminates population structure and history, has potential applications in forensic studies and, in the form of 'genetic genealogy', is an area of rapidly growing interest for the public.

Joint analysis of multiple biomarkers for identifying type 2 diabetes in middle-aged and older Chinese: a cross-sectional study

PubMed Central

Wu, Hongyu; Yu, Zhijie; Qi, Qibin; Li, Huaixing; Sun, Qi

2011-01-01

Objective Identifying individuals with high risk of type 2 diabetes is important. To evaluate discriminatory ability of multiple biomarkers for type 2 diabetes in a Chinese population. Methods Plasma adiponectin, plasminogen activator inhibitor-1, retinol-binding protein 4, resistin, C-reactive protein, interleukin 6 (IL-6), tumour necrosis factor α receptor 2 and ferritin were measured in a population-based sample of 3189 Chinese (1419 men and 1770 women) aged 50–70 years. A weighted biomarkers risk score (BRS) was developed based on the strength of associations of these biomarkers with type 2 diabetes. The discriminatory ability was tested by the area under receiver operating characteristics curve (AUC). Results Adiponectin, plasminogen activator inhibitor-1, IL-6 and ferritin were independently associated with the prevalence of type 2 diabetes, and they were used to calculate the biomarkers risk score (BRS). After adjustment for the confounding factors, the ORs for type 2 diabetes and impaired fasting glucose with each point increment of BRS were 1.28 (95% CI 1.22 to 1.34) and 1.16 (1.12 to 1.20), respectively. Compared with those in the lowest quintile of the BRS, the participants in the highest quintile have an OR (95% CI) of 6.67 (4.21 to 10.55) for type 2 diabetes. The area under the curve for the BRS and conventional risk factors alone was 0.73 and 0.76, respectively, and substantially increased to 0.81 after combining both BRS and conventional risk factors (p<0.001). Conclusions These data suggest that combining multiple biomarkers and conventional risk factors might substantially enhance the ability to identify individuals with type 2 diabetes. More prospective data are warranted to confirm this observation. PMID:22021786

Dose-response relationships between internally-deposited uranium and select health outcomes in gaseous diffusion plant workers, 1948-2011.

PubMed

Yiin, James H; Anderson, Jeri L; Bertke, Stephen J; Tollerud, David J

2018-05-09

To examine dose-response relationships between internal uranium exposures and select outcomes among a cohort of uranium enrichment workers. Cox regression was conducted to examine associations between selected health outcomes and cumulative internal uranium with consideration for external ionizing radiation, work-related medical X-rays and contaminant radionuclides technetium ( 99 Tc) and plutonium ( 239 Pu) as potential confounders. Elevated and monotonically increasing mortality risks were observed for kidney cancer, chronic renal diseases, and multiple myeloma, and the association with internal uranium absorbed organ dose was statistically significant for multiple myeloma. Adjustment for potential confounders had minimal impact on the risk estimates. Kidney cancer, chronic renal disease, and multiple myeloma mortality risks were elevated with increasing internal uranium absorbed organ dose. The findings add to evidence of an association between internal exposure to uranium and cancer. Future investigation includes a study of cancer incidence in this cohort. © 2018 Wiley Periodicals, Inc.

Integrated presentation of ecological risk from multiple stressors

NASA Astrophysics Data System (ADS)

Goussen, Benoit; Price, Oliver R.; Rendal, Cecilie; Ashauer, Roman

2016-10-01

Current environmental risk assessments (ERA) do not account explicitly for ecological factors (e.g. species composition, temperature or food availability) and multiple stressors. Assessing mixtures of chemical and ecological stressors is needed as well as accounting for variability in environmental conditions and uncertainty of data and models. Here we propose a novel probabilistic ERA framework to overcome these limitations, which focusses on visualising assessment outcomes by construct-ing and interpreting prevalence plots as a quantitative prediction of risk. Key components include environmental scenarios that integrate exposure and ecology, and ecological modelling of relevant endpoints to assess the effect of a combination of stressors. Our illustrative results demonstrate the importance of regional differences in environmental conditions and the confounding interactions of stressors. Using this framework and prevalence plots provides a risk-based approach that combines risk assessment and risk management in a meaningful way and presents a truly mechanistic alternative to the threshold approach. Even whilst research continues to improve the underlying models and data, regulators and decision makers can already use the framework and prevalence plots. The integration of multiple stressors, environmental conditions and variability makes ERA more relevant and realistic.

Integrated presentation of ecological risk from multiple stressors.

PubMed

Goussen, Benoit; Price, Oliver R; Rendal, Cecilie; Ashauer, Roman

2016-10-26

Current environmental risk assessments (ERA) do not account explicitly for ecological factors (e.g. species composition, temperature or food availability) and multiple stressors. Assessing mixtures of chemical and ecological stressors is needed as well as accounting for variability in environmental conditions and uncertainty of data and models. Here we propose a novel probabilistic ERA framework to overcome these limitations, which focusses on visualising assessment outcomes by construct-ing and interpreting prevalence plots as a quantitative prediction of risk. Key components include environmental scenarios that integrate exposure and ecology, and ecological modelling of relevant endpoints to assess the effect of a combination of stressors. Our illustrative results demonstrate the importance of regional differences in environmental conditions and the confounding interactions of stressors. Using this framework and prevalence plots provides a risk-based approach that combines risk assessment and risk management in a meaningful way and presents a truly mechanistic alternative to the threshold approach. Even whilst research continues to improve the underlying models and data, regulators and decision makers can already use the framework and prevalence plots. The integration of multiple stressors, environmental conditions and variability makes ERA more relevant and realistic.

Clinical and evoked pain, personality traits, and emotional states: can familial confounding explain the associations?

PubMed

Strachan, Eric; Poeschla, Brian; Dansie, Elizabeth; Succop, Annemarie; Chopko, Laura; Afari, Niloofar

2015-01-01

Pain is a complex phenomenon influenced by context and person-specific factors. Affective dimensions of pain involve both enduring personality traits and fleeting emotional states. We examined how personality traits and emotional states are linked with clinical and evoked pain in a twin sample. 99 female twin pairs were evaluated for clinical and evoked pain using the McGill Pain Questionnaire (MPQ) and dolorimetry, and completed the 120-item International Personality Item Pool (IPIP), the Positive and Negative Affect Scale (PANAS), and ratings of stress and mood. Using a co-twin control design we examined a) the relationship of personality traits and emotional states with clinical and evoked pain and b) whether genetics and common environment (i.e. familial factors) may account for the associations. Neuroticism was associated with the sensory component of the MPQ; this relationship was not confounded by familial factors. None of the emotional state measures was associated with the MPQ. PANAS negative affect was associated with lower evoked pressure pain threshold and tolerance; these associations were confounded by familial factors. There were no associations between IPIP traits and evoked pain. A relationship exists between neuroticism and clinical pain that is not confounded by familial factors. There is no similar relationship between negative emotional states and clinical pain. In contrast, the relationship between negative emotional states and evoked pain is strong while the relationship with enduring personality traits is weak. The relationship between negative emotional states and evoked pain appears to be non-causal and due to familial factors. Copyright © 2014 Elsevier Inc. All rights reserved.

Phenotypic variation as an indicator of pesticide stress in gudgeon: Accounting for confounding factors in the wild.

PubMed

Shinn, Cândida; Blanchet, Simon; Loot, Géraldine; Lek, Sovan; Grenouillet, Gaël

2015-12-15

The response of organisms to environmental stress is currently used in the assessment of ecosystem health. Morphological changes integrate the multiple effects of one or several stress factors upon the development of the exposed organisms. In a natural environment, many factors determine the patterns of morphological differentiation between individuals. However, few studies have sought to distinguish and measure the independent effect of these factors (genetic diversity and structure, spatial structuring of populations, physical-chemical conditions, etc.). Here we investigated the relationship between pesticide levels measured at 11 sites sampled in rivers of the Garonne river basin (SW France) and morphological changes of a freshwater fish species, the gudgeon (Gobio gobio). Each individual sampled was genotyped using 8 microsatellite markers and their phenotype characterized via 17 morphological traits. Our analysis detected a link between population genetic structure (revealed by a Bayesian method) and morphometry (linear discriminant analysis) of the studied populations. We then developed an original method based on general linear models using distance matrices, an extension of the partial Mantel test beyond 3 matrices. This method was used to test the relationship between contamination (toxicity index) and morphometry (PST of morphometric traits), taking into account (1) genetic differentiation between populations (FST), (2) geographical distances between sites, (3) site catchment area, and (4) various physical-chemical parameters for each sampling site. Upon removal of confounding effects, 3 of the 17 morphological traits studied were significantly correlated with pesticide toxicity, suggesting a response of these traits to the anthropogenic stress. These results underline the importance of taking into account the different sources of phenotypic variability between organisms when identifying the stress factors involved. The separation and quantification of the independent effect of such factors provides an interesting outlook regarding the use of these evaluation metrics as indicators of ecosystem health. Copyright © 2015 Elsevier B.V. All rights reserved.

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

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.

Midlife work-related stress is associated with late-life cognition.

PubMed

Sindi, Shireen; Kåreholt, Ingemar; Solomon, Alina; Hooshmand, Babak; Soininen, Hilkka; Kivipelto, Miia

2017-09-01

To investigate the associations between midlife work-related stress and late-life cognition in individuals without dementia from the general population. The Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study population (n = 2000) was randomly selected from independent Finnish population-based surveys (baseline mean age 50 years). Participants underwent two re-examinations in late life (mean age 71 and 78 years, respectively). 1511 subjects participated in at least one re-examination (mean total follow-up 25 years). Work-related stress was measured using two questions on work demands administered in midlife. Multiple cognitive domains were assessed. Analyses were adjusted for several potential confounders. Higher levels of midlife work-related stress were associated with poorer performance on global cognition [β-coefficient, -0.02; 95% confidence interval (CI), -0.05 to -0.00], and processing speed [β -0.03, CI -0.05 to -0.01]. Results remained significant after adjusting for potential confounders. Work-related stress was not significantly associated with episodic memory, executive functioning, verbal fluency or manual dexterity. This study shows that global cognition and processing speed may be particularly susceptible to the effects of midlife work-related stress.

Pain of methadone-maintained heroin addicts: lonelier individuals feel more intense pain.

PubMed

Li, Fu; Xu, Yan-Min; Zhu, Jun-Hong; Lu, Jin; Zhong, Bao-Liang

2017-10-03

Managing pain in patients with heroin addiction is challenging, because most pain medications are addictive. A promising way to relieve pain of heroin addicts is to identify and address modifiable psychosocial factors associated with pain. This study examined the association between loneliness and pain intensity in Chinese heroin addicts receiving methadone maintenance treatment (MMT). A consecutive sample of 603 heroin addicts were recruited from three MMT clinics in Wuhan, China. Loneliness was assessed with a single question, and socio-demographic and clinical data were collected with a standardized questionnaire. Pain intensity was assessed with the five-point Verbal Rating Scale. Multiple ordinary logistic regression was used to control for potential confounders that may bias the loneliness-pain relationship. There was a significant and positive correlation between pain intensity and loneliness scores among methadone-maintained heroin addicts ( r = 0.453, P < 0.001). After controlling for potential socio-demographic and clinical confounders, an increase in the level of loneliness was significantly associated with an increase in pain intensity (OR = 1.22, P = 0.042). Loneliness is significantly associated with pain of methadone-maintained heroin addicts. Psychosocial interventions aimed at reducing loneliness might prevent or reduce pain of patients receiving MMT.

Smoking and cognitive impairment among older persons in Malaysia.

PubMed

Momtaz, Yadollah Abolfathi; Ibrahim, Rahimah; Hamid, Tengku Aizan; Chai, Sen Tyng

2015-06-01

Previous studies have shown conflicting results on the association between smoking and cognitive function. This study aims to examine the relationship of smoking with cognitive function. Data for the study, consisting of 2553 older adults aged 60 years and older, were drawn from a nationwide household survey entitled "Determinants of Wellness among Older Malaysians: A Health Promotion Perspective" conducted in 2010. Current smokers had lower rates of cognitive impairment compared to never smokers (17.4% vs 25.9%), while cognitive function in former or ex-smokers was almost similar to that of the never smokers. Findings from multiple logistic regression analysis showed that current smokers were 37% less likely to be cognitively impaired, compared to the never smokers (odds ratio [OR] = .63; 95% confidence interval [CI]: .46-.86) while controlling for potential confounders. No difference in cognitive function was observed between former smokers and never smokers (OR = .94; 95% CI: .71-1.25). Although the findings indicated a negative association between cigarette smoking and cognitive impairment, we are unable to conclude whether this relationship is causal or affected by other unmeasured confounding factors, especially survival bias. © The Author(s) 2014.

Effects of low-dose radiation - a correlation study.

PubMed

Edling, C; Comba, P; Axelson, O; Flodin, U

1982-01-01

The effects of low-dose radiation have been a matter of controversy over the years, and the epidemiologic results have been conflicting. A couple of recent studies have indicated a possible impact on lung cancer mortality from exposure to indoor levels of radon and radon daughters. In this study, selected mortality rates, ie, lung cancer, pancreatic cancer, breast cancer (females only), leukemia, and multiple myeloma were correlated for the counties of Sweden with estimates of average background radiation exposure in these areas. Significant correlations were obtained for lung cancer (males, r = 0.46; females r = 0.55) and pancreatic cancer (males, r = 0.59; females, r = 0.40) , and there was a borderline correlation (r = 0.36; p = 0.04) for leukemia in males. In all, there were positive correlations for eight out of the nine computations made. Since background radiation correlates with urbanization and therefore with smoking, air pollution, etc, the correlations might be spurious due to confounding; on the other hand confounding is a reciprocal phenomenon which suggests that background radiation should to be taken into consideration when widespread risk factors like smoking, coffee drinking, general air pollution, etc, are studied.

Suicidal Ideation and Mental Distress Among Adults With Military Service History: Results From 5 US States, 2010

PubMed Central

Gordon, Adam J.; Bossarte, Robert M.

2014-01-01

Objectives. We examined the association of military service history with past-year suicidal ideation and past-30-days mental distress in a probability-based sample of adults. Methods. We gathered 2010 Behavioral Risk Factor Surveillance System data from 5 states that asked about past-year suicidal ideation. Military service was defined as current or former active-duty service or National Guard or Reserves service. We stratified analyses into 18 to 39 years, 40 to 64 years, and 65 years and older age groups and used multiple logistic regression analyses, adjusted for demographic confounders, to discern the association of military service history with past-year suicidal ideation and past-30-days mental distress. Results. Among the 26 736 respondents, 13.1% indicated military service history. After adjusting for several confounders, we found military history status among those aged 40 to 64 years was associated with both past-year suicidal ideation and past-30-days mental distress. We found no significant associations among the younger or older age groups. Conclusions. Differences in suicidal ideation between military and nonmilitary individuals may occur in midlife. Future research should examine the possibility of cohort effects, service era effects, or both. PMID:25100426

Procedural Factors That Affect Psychophysical Measures of Spatial Selectivity in Cochlear Implant Users

PubMed Central

Deeks, John M.; Carlyon, Robert P.

2015-01-01

Behavioral measures of spatial selectivity in cochlear implants are important both for guiding the programing of individual users’ implants and for the evaluation of different stimulation methods. However, the methods used are subject to a number of confounding factors that can contaminate estimates of spatial selectivity. These factors include off-site listening, charge interactions between masker and probe pulses in interleaved masking paradigms, and confusion effects in forward masking. We review the effects of these confounds and discuss methods for minimizing them. We describe one such method in which the level of a 125-pps masker is adjusted so as to mask a 125-pps probe, and where the masker and probe pulses are temporally interleaved. Five experiments describe the method and evaluate the potential roles of the different potential confounding factors. No evidence was obtained for off-site listening of the type observed in acoustic hearing. The choice of the masking paradigm was shown to alter the measured spatial selectivity. For short gaps between masker and probe pulses, both facilitation and refractory mechanisms had an effect on masking; this finding should inform the choice of stimulation rate in interleaved masking experiments. No evidence for confusion effects in forward masking was revealed. It is concluded that the proposed method avoids many potential confounds but that the choice of method should depend on the research question under investigation. PMID:26420785

Gait initiation time is associated with the risk of multiple falls-A population-based study.

PubMed

Callisaya, Michele L; Blizzard, Leigh; Martin, Kara; Srikanth, Velandai K

2016-09-01

In a population-based study of older people to examine whether 1) overall gait initiation (GI) time or its components are associated with falls and 2) GI under dual-task is a stronger predictor of falls risk than under single-task. Participants aged 60-85 years were randomly selected from the electoral roll. GI was obtained with a force platform under both single and dual-task conditions. Falls were ascertained prospectively over a 12-month period. Log multinomial regression was used to examine the association between GI time (total and its components) and risk of single and multiple falls. Age, sex and physiological and cognitive falls risk factors were considered as confounders. The mean age of the sample (n=124) was 71.0 (SD 6.8) years and 58.9% (n=73) were male. Over 12 months 21.8% (n=27) of participants reported a single fall and 16.1% (n=20) reported multiple falls. Slower overall GI time under both single (RR all per 100ms 1.28, 95%CI 1.03, 1.58) and dual-task (RR 1.14, 95%CI 1.02, 1.27) was associated with increased risk of multiple, but not single falls (p<0.05). Multiple falls were also associated with slower time to first lateral movement under single-task (RR 1.90 95%CI 0.59, 1.51) and swing time under dual-task condition (RR 1.44 95%CI 1.08, 1.94). Slower GI time is associated with the risk of multiple falls independent of other risk factors, suggesting it could be used as part of a comprehensive falls assessment. Time to the first lateral movement under single-task may be the best measures of this risk. Copyright © 2016 Elsevier B.V. All rights reserved.

[FROM STATISTICAL ASSOCIATIONS TO SCIENTIFIC CAUSALITY].

PubMed

Golan, Daniel; Linn, Shay

2015-06-01

The pathogenesis of most chronic diseases is complex and probably involves the interaction of multiple genetic and environmental risk factors. One way to learn about disease triggers is from statistically significant associations in epidemiological studies. However, associations do not necessarily prove causation. Associations can commonly result from bias, confounding and reverse causation. Several paradigms for causality inference have been developed. Henle-Koch postulates are mainly applied for infectious diseases. Austin Bradford Hill's criteria may serve as a practical tool to weigh the evidence regarding the probability that a single new risk factor for a given disease is indeed causal. These criteria are irrelevant for estimating the causal relationship between exposure to a risk factor and disease whenever biological causality has been previously established. Thus, it is highly probable that past exposure of an individual to definite carcinogens is related to his cancer, even without proving an association between this exposure and cancer in his group. For multifactorial diseases, Rothman's model of interacting sets of component causes can be applied.

Health-Related Quality of Life Among US Workers: Variability Across Occupation Groups.

PubMed

Shockey, Taylor M; Zack, Matthew; Sussell, Aaron

2017-08-01

To examine the health-related quality of life among workers in 22 standard occupation groups using data from the 2013-2014 US Behavioral Risk Factor Surveillance System. We examined the health-related quality of life measures of self-rated health, frequent physical distress, frequent mental distress, frequent activity limitation, and frequent overall unhealthy days by occupation group for 155 839 currently employed adults among 17 states. We performed multiple logistic regression analyses that accounted for the Behavioral Risk Factor Surveillance System's complex survey design to obtain prevalence estimates adjusted for potential confounders. Among all occupation groups, the arts, design, entertainment, sports, and media occupation group reported the highest adjusted prevalence of frequent physical distress, frequent mental distress, frequent activity limitation, and frequent overall unhealthy days. The personal care and service occupation group had the highest adjusted prevalence for fair or poor self-rated health. Workers' jobs affect their health-related quality of life.

Generalizability of dietary patterns of the inverse association between alcohol consumption and type 2 diabetes risk

USDA-ARS?s Scientific Manuscript database

Epidemiology of dietary components and disease risk limits interpretability due to potential residual confounding by correlated dietary components. Dietary pattern analyses by factor analysis or partial least squares may overcome this limitation. To examine confounding by dietary pattern as well as ...

Risk Factors for 30-Day Complications After Thumb CMC Joint Arthroplasty: An American College of Surgeons National Surgery Quality Improvement Program Study.

PubMed

Shah, Kalpit N; Defroda, Steven F; Wang, Bo; Weiss, Arnold-Peter C

2017-12-01

The first carpometacarpal (CMC) joint is a common site of osteoarthritis, with arthroplasty being a common procedure to provide pain relief and improve function with low complications. However, little is known about risk factors that may predispose a patient for postoperative complications. All CMC joint arthroplasty from 2005 to 2015 in the prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database were identified. Bivariate testing and multiple logistic regressions were performed to determine which patient demographics, surgical variables and medical comorbidities were significant predictors for complications. These included wound related, cardiopulmonary, neurological and renal complications, return to the operating room (OR) and readmission. A total of 3344 patients were identified from the database. Of those, 45 patients (1.3%) experienced a complication including wound issues (0.66%), return to the OR (0.15%) and readmission (0.27%) amongst others. When performing bivariate analysis, age over 65, American Society of Anesthesiologists (ASA) Class, diabetes and renal dialysis were significant risk factors. Multiple logistic regression after adjusting for confounding factors demonstrated that insulin-dependent diabetes and ASA Class 4 had a strong trend while renal dialysis was a significant risk factor. CMC arthroplasty has a very low overall complication rate of 1.3% and wound complication rate of 0.66%. Diabetes requiring insulin and ASA Class 4 trended towards significance while renal dialysis was found to be a significant risk factors in logistic regression. This information may be useful for preoperative counseling and discussion with patients who have these risk factors.

Neonatal Pain-Related Stress Predicts Cortical Thickness at Age 7 Years in Children Born Very Preterm

PubMed Central

Ranger, Manon; Chau, Cecil M. Y.; Garg, Amanmeet; Woodward, Todd S.; Beg, Mirza Faisal; Bjornson, Bruce; Poskitt, Kenneth; Fitzpatrick, Kevin; Synnes, Anne R.; Miller, Steven P.; Grunau, Ruth E.

2013-01-01

Background Altered brain development is evident in children born very preterm (24–32 weeks gestational age), including reduction in gray and white matter volumes, and thinner cortex, from infancy to adolescence compared to term-born peers. However, many questions remain regarding the etiology. Infants born very preterm are exposed to repeated procedural pain-related stress during a period of very rapid brain development. In this vulnerable population, we have previously found that neonatal pain-related stress is associated with atypical brain development from birth to term-equivalent age. Our present aim was to evaluate whether neonatal pain-related stress (adjusted for clinical confounders of prematurity) is associated with altered cortical thickness in very preterm children at school age. Methods 42 right-handed children born very preterm (24–32 weeks gestational age) followed longitudinally from birth underwent 3-D T1 MRI neuroimaging at mean age 7.9 yrs. Children with severe brain injury and major motor/sensory/cognitive impairment were excluded. Regional cortical thickness was calculated using custom developed software utilizing FreeSurfer segmentation data. The association between neonatal pain-related stress (defined as the number of skin-breaking procedures) accounting for clinical confounders (gestational age, illness severity, infection, mechanical ventilation, surgeries, and morphine exposure), was examined in relation to cortical thickness using constrained principal component analysis followed by generalized linear modeling. Results After correcting for multiple comparisons and adjusting for neonatal clinical factors, greater neonatal pain-related stress was associated with significantly thinner cortex in 21/66 cerebral regions (p-values ranged from 0.00001 to 0.014), predominately in the frontal and parietal lobes. Conclusions In very preterm children without major sensory, motor or cognitive impairments, neonatal pain-related stress appears to be associated with thinner cortex in multiple regions at school age, independent of other neonatal risk factors. PMID:24204657

Risk Factors in Adolescent Hypertension

PubMed Central

Ewald, D. Rose; Haldeman, Lauren A.

2016-01-01

Hypertension is a complex and multifaceted disease, with many contributing factors. While diet and nutrition are important influences, the confounding effects of overweight and obesity, metabolic and genetic factors, racial and ethnic predispositions, socioeconomic status, cultural influences, growth rate, and pubertal stage have even more influence and make diagnosis quite challenging. The prevalence of hypertension in adolescents far exceeds the numbers who have been diagnosed; studies have found that 75% or more go undiagnosed. This literature review summarizes the challenges of blood pressure classification in adolescents, discusses the impact of these confounding influences, and identifies actions that will improve diagnosis and treatment outcomes. PMID:27335997

Comorbidities confounding the outcomes of surgery for third window syndrome: Outlier analysis

PubMed Central

Mackay‐Promitas, Heather T.; Demirel, Shaban; Gianoli, Gerard J.; Gizzi, Martin S.; Carter, Dale M.; Siker, David A.

2017-01-01

Objective Patients with third window syndrome and superior semicircular canal dehiscence (SSCD) symptoms whose surgical outcomes placed them as outliers were systematically studied to determine comorbidities that were responsible for their poor outcomes due to these confounding factors. Study Design Observational analytic case‐control study in a tertiary referral center. Methods Twelve adult patients with clinical SSCD syndrome underwent surgical management and had outcomes that did not resolve all of their subjective symptoms. In addition to one of the neurotologists, 2 neurologists (one specializing in migraine and the other a neuro‐ophthalmologist), and a psychologist clinician‐investigator completed comprehensive evaluations. Neuropsychology test batteries included: the Millon Behavioral Medicine Diagnostic; Patient Health Questionnaire (PHQ‐9) and Generalized Anxiety Disorder Screener (GAD‐7); Adverse Childhood Experiences Scale; the Wide Range Assessment of Memory and Learning, including the 3 domains of verbal memory, visual memory, and attention/concentration; Wechsler Adult Intelligence Scale; and the Delis‐Kaplan Executive Function System. The control cohort was comprised of 17 participants who previously underwent surgery for third window syndrome that resulted in the expected outcomes of resolution of their third window syndrome symptoms and cognitive dysfunction. Results There was a high rate of psychological comorbidity (n = 6) in the outlier cohort; multiple traumatic brain injuries were also a confounding element (n = 10). One patient had elevated cerebrospinal fluid (CSF) pressure requiring ventriculoperitoneal shunting to control the recurrence of dehiscence and one patient with a drug‐induced Parkinson‐like syndrome and idiopathic progressive neurological degenerative process. Conclusions Components of the Millon Behavioral Medicine Diagnostic, PHQ‐9 and GAD‐7 results suggest that these instruments would be useful as screening tools preoperatively to identify psychological comorbidities that could confound outcomes. The identification of these comorbid psychological as well as other neurological degenerative disease processes led to alternate clinical management pathways for these patients. Level of Evidence 2b. PMID:29094067

Are Interactions between cis-Regulatory Variants Evidence for Biological Epistasis or Statistical Artifacts?

PubMed

Fish, Alexandra E; Capra, John A; Bush, William S

2016-10-06

The importance of epistasis-or statistical interactions between genetic variants-to the development of complex disease in humans has been controversial. Genome-wide association studies of statistical interactions influencing human traits have recently become computationally feasible and have identified many putative interactions. However, statistical models used to detect interactions can be confounded, which makes it difficult to be certain that observed statistical interactions are evidence for true molecular epistasis. In this study, we investigate whether there is evidence for epistatic interactions between genetic variants within the cis-regulatory region that influence gene expression after accounting for technical, statistical, and biological confounding factors. We identified 1,119 (FDR = 5%) interactions that appear to regulate gene expression in human lymphoblastoid cell lines, a tightly controlled, largely genetically determined phenotype. Many of these interactions replicated in an independent dataset (90 of 803 tested, Bonferroni threshold). We then performed an exhaustive analysis of both known and novel confounders, including ceiling/floor effects, missing genotype combinations, haplotype effects, single variants tagged through linkage disequilibrium, and population stratification. Every interaction could be explained by at least one of these confounders, and replication in independent datasets did not protect against some confounders. Assuming that the confounding factors provide a more parsimonious explanation for each interaction, we find it unlikely that cis-regulatory interactions contribute strongly to human gene expression, which calls into question the relevance of cis-regulatory interactions for other human phenotypes. We additionally propose several best practices for epistasis testing to protect future studies from confounding. Copyright © 2016 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Revisiting the Table 2 fallacy: A motivating example examining preeclampsia and preterm birth.

PubMed

Bandoli, Gretchen; Palmsten, Kristin; Chambers, Christina D; Jelliffe-Pawlowski, Laura L; Baer, Rebecca J; Thompson, Caroline A

2018-05-21

A "Table Fallacy," as coined by Westreich and Greenland, reports multiple adjusted effect estimates from a single model. This practice, which remains common in published literature, can be problematic when different types of effect estimates are presented together in a single table. The purpose of this paper is to quantitatively illustrate this potential for misinterpretation with an example estimating the effects of preeclampsia on preterm birth. We analysed a retrospective population-based cohort of 2 963 888 singleton births in California between 2007 and 2012. We performed a modified Poisson regression to calculate the total effect of preeclampsia on the risk of PTB, adjusting for previous preterm birth. pregnancy alcohol abuse, maternal education, and maternal socio-demographic factors (Model 1). In subsequent models, we report the total effects of previous preterm birth, alcohol abuse, and education on the risk of PTB, comparing and contrasting the controlled direct effects, total effects, and confounded effect estimates, resulting from Model 1. The effect estimate for previous preterm birth (a controlled direct effect in Model 1) increased 10% when estimated as a total effect. The risk ratio for alcohol abuse, biased due to an uncontrolled confounder in Model 1, was reduced by 23% when adjusted for drug abuse. The risk ratio for maternal education, solely a predictor of the outcome, was essentially unchanged. Reporting multiple effect estimates from a single model may lead to misinterpretation and lack of reproducibility. This example highlights the need for careful consideration of the types of effects estimated in statistical models. © 2018 John Wiley & Sons Ltd.

Addressing unmeasured confounding in comparative observational research.

PubMed

Zhang, Xiang; Faries, Douglas E; Li, Hu; Stamey, James D; Imbens, Guido W

2018-04-01

Observational pharmacoepidemiological studies can provide valuable information on the effectiveness or safety of interventions in the real world, but one major challenge is the existence of unmeasured confounder(s). While many analytical methods have been developed for dealing with this challenge, they appear under-utilized, perhaps due to the complexity and varied requirements for implementation. Thus, there is an unmet need to improve understanding the appropriate course of action to address unmeasured confounding under a variety of research scenarios. We implemented a stepwise search strategy to find articles discussing the assessment of unmeasured confounding in electronic literature databases. Identified publications were reviewed and characterized by the applicable research settings and information requirements required for implementing each method. We further used this information to develop a best practice recommendation to help guide the selection of appropriate analytical methods for assessing the potential impact of unmeasured confounding. Over 100 papers were reviewed, and 15 methods were identified. We used a flowchart to illustrate the best practice recommendation which was driven by 2 critical components: (1) availability of information on the unmeasured confounders; and (2) goals of the unmeasured confounding assessment. Key factors for implementation of each method were summarized in a checklist to provide further assistance to researchers for implementing these methods. When assessing comparative effectiveness or safety in observational research, the impact of unmeasured confounding should not be ignored. Instead, we suggest quantitatively evaluating the impact of unmeasured confounding and provided a best practice recommendation for selecting appropriate analytical methods. Copyright © 2018 John Wiley & Sons, Ltd.

Interventional effects for mediation analysis with multiple mediators

PubMed Central

Vansteelandt, Stijn; Daniel, Rhian M.

2016-01-01

The mediation formula for the identification of natural (in)direct effects has facilitated mediation analyses that better respect the nature of the data, with greater consideration of the need for confounding control. The default assumptions on which it relies are strong, however. In particular, they are known to be violated when confounders of the mediator–outcome association are affected by the exposure. This complicates extensions of counterfactual-based mediation analysis to settings that involve repeatedly measured mediators, or multiple correlated mediators. VanderWeele, Vansteelandt, and Robins21 introduced so-called interventional (in)direct effects. These can be identified under much weaker conditions than natural (in)direct effects, but have the drawback of not adding up to the total effect. In this article, we adapt their proposal in order to achieve an exact decomposition of the total effect, and extend it to the multiple mediator setting. Interestingly, the proposed effects capture the path-specific effects of an exposure on an outcome that are mediated by distinct mediators, even when – as often – the structural dependence between the multiple mediators is unknown; for instance, when the direction of the causal effects between the mediators is unknown, or there may be unmeasured common causes of the mediators. PMID:27922534

Interventional Effects for Mediation Analysis with Multiple Mediators.

PubMed

Vansteelandt, Stijn; Daniel, Rhian M

2017-03-01

The mediation formula for the identification of natural (in)direct effects has facilitated mediation analyses that better respect the nature of the data, with greater consideration of the need for confounding control. The default assumptions on which it relies are strong, however. In particular, they are known to be violated when confounders of the mediator-outcome association are affected by the exposure. This complicates extensions of counterfactual-based mediation analysis to settings that involve repeatedly measured mediators, or multiple correlated mediators. VanderWeele, Vansteelandt, and Robins introduced so-called interventional (in)direct effects. These can be identified under much weaker conditions than natural (in)direct effects, but have the drawback of not adding up to the total effect. In this article, we adapt their proposal to achieve an exact decomposition of the total effect, and extend it to the multiple mediator setting. Interestingly, the proposed effects capture the path-specific effects of an exposure on an outcome that are mediated by distinct mediators, even when-as often-the structural dependence between the multiple mediators is unknown, for instance, when the direction of the causal effects between the mediators is unknown, or there may be unmeasured common causes of the mediators.

A cross-sectional study to estimate associations between education level and osteoporosis in a Chinese postmenopausal women sample.

PubMed

Piao, Hui-Hong; He, Jiajia; Zhang, Keqin; Tang, Zihui

2015-01-01

Our research aims to investigate the associations between education level and osteoporosis (OP) in Chinese postmenopausal women. A large-scale, community-based, cross-sectional study was conducted to examine the associations between education level and OP. A self-reported questionnaire was used to access the demographical information and medical history of the participants. A total of 1905 postmenopausal women were available for data analysis in this study. Multiple regression models controlling for confounding factors to include education level were performed to investigate the relationship with OP. The prevalence of OP was 28.29% in our study sample. Multivariate linear regression analyses adjusted for relevant potential confounding factors detected significant associations between education level and T-score (β = 0.025, P-value = 0.095, 95% CI: -0.004-0.055 for model 1; and β = 0.092, P-value = 0.032, 95% CI: 0.008-0.175 for model 2). Multivariate logistic regression analyses detected significant associations between education level and OP in model 1 (P-value = 0.070 for model 1, Table 5), while no significant associations was reported in model 2 (P value = 0.131). In participants with high education levels, the OR for OP was 0.914 (95% CI: 0.830-1.007). The findings indicated that education level was independently and significantly associated with OP. The prevalence of OP was more frequent in Chinese postmenopausal women with low educational status.

Using ecological propensity score to adjust for missing confounders in small area studies.

PubMed

Wang, Yingbo; Pirani, Monica; Hansell, Anna L; Richardson, Sylvia; Blangiardo, Marta

2017-11-09

Small area ecological studies are commonly used in epidemiology to assess the impact of area level risk factors on health outcomes when data are only available in an aggregated form. However, the resulting estimates are often biased due to unmeasured confounders, which typically are not available from the standard administrative registries used for these studies. Extra information on confounders can be provided through external data sets such as surveys or cohorts, where the data are available at the individual level rather than at the area level; however, such data typically lack the geographical coverage of administrative registries. We develop a framework of analysis which combines ecological and individual level data from different sources to provide an adjusted estimate of area level risk factors which is less biased. Our method (i) summarizes all available individual level confounders into an area level scalar variable, which we call ecological propensity score (EPS), (ii) implements a hierarchical structured approach to impute the values of EPS whenever they are missing, and (iii) includes the estimated and imputed EPS into the ecological regression linking the risk factors to the health outcome. Through a simulation study, we show that integrating individual level data into small area analyses via EPS is a promising method to reduce the bias intrinsic in ecological studies due to unmeasured confounders; we also apply the method to a real case study to evaluate the effect of air pollution on coronary heart disease hospital admissions in Greater London. © The Author 2017. Published by Oxford University Press.

The link between discrimination and telomere length in African American adults.

PubMed

Lee, Daniel B; Kim, Eric S; Neblett, Enrique W

2017-05-01

Prior work shows that discrimination is associated with a wide array of negative health outcomes. However, the biological mechanisms through which this link occurs require more study. We evaluated the association between discrimination and leukocyte telomere length (LTL; a biological marker of systemic aging). Cross-sectional data were from the Health and Retirement study, a study of people aged 51+ in the United States, and included 595 African American males and females. Multiple regression analyses were used to evaluate whether discrimination was independently associated with LTL. We also considered the role of potential confounders including sociodemographic factors, health factors, depressive symptoms, and stress. High discrimination was associated with shorter LTL after controlling for sociodemographic factors (b = -.034, SE = 0.14, p = .017). This association persisted in analyses that further adjusted for health factors, depressive symptoms, and stress. Results suggest that discrimination experiences accelerate biological aging in older African American males and females, alike. This finding helps advance our understanding of how discrimination generates greater disease vulnerability and premature death in African Americans. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Inhibitory Control in Siblings Discordant for Exposure to Maternal Smoking during Pregnancy

ERIC Educational Resources Information Center

Micalizzi, Lauren; Marceau, Kristine; Brick, Leslie A.; Palmer, Rohan H.; Todorov, Alexandre A.; Heath, Andrew C.; Evans, Allison; Knopik, Valerie S.

2018-01-01

Maternal smoking during pregnancy (SDP) has been linked to poorer offspring executive function across development, but SDP does not occur independent of other familial risk factors. As such, poor and inconsistent control for potential confounds, notably shared familial (i.e., genetic and environmental) confounds, preclude concluding causal effects…

Relationships of colorectal cancer with dietary factors and public health indicators: an ecological study.

PubMed

Abbastabar, Hedayat; Roustazadeh, Abazar; Alizadeh, Ali; Hamidifard, Parvin; Valipour, Mehrdad; Valipour, Ali Asghar

2015-01-01

Colorectal cancer (CRC) is the third most common cancer in Iranian women and fifth in men. The aims of this study were to investigate the relation of dietary factors and public health indicators to its development. The required information (2001-2006) about risk factors was obtained from the Non- Communicable Disease Surveillance Centre (NCDSC) of Iran. Risk factor data (RFD) from 89,404 individuals (15-64 years old) were gathered by questionnaire and laboratory examinations through a cross sectional study in all provinces by systematic clustering sampling method. CRC incidence segregated by age and gender was obtained from Cancer Registry Ministry of Health (CRMH) of Iran. First, correlation coefficients were used for data analysis and then multiple regression analysis was performed to control for confounding factors. Colorectal cancer incidence showed a positive relationship with diabetes mellitus, hypertension, lacking or low physical activity, high education, high intake of dairy products, and non-consumption of vegetables and fruits. We concluded that many dietary factors and public health indicators have positive relationships with CRC and might therefore be targets of preliminary prevention. However, since this is an ecological study limited by potential ecological fallacy the results must be interpreted with caution.

[Shift work and night work: what effect on blood pressure?].

PubMed

Cassat, M; Wuerzner, G; Burnier, M

2015-09-09

Shift work has become more and more common for the last thirty years. By definition, shift work disturbs the circadian rhythm and the internal clock. Even if the pathophysiological mechanisms are not well understood, a greater cardiovascular risk has been attributed to shift work. Cross-sectional and cohort studies have identified an association between shift work and an elevated blood pressure. Shift workers also present a higher incidence of hypertension and progression than day workers. Unfortunately, the heterogeneity of the studies, the multiple confounding factors, as well as the complexity to achieve a suitable comparison group make it impossible to draw firm clinical evidence. Nevertheless, this population needs a medical follow-up focused on the cardiovascular risks and blood pressure.

Occupational exposure to glycol ethers: implications for occupational health nurses.

PubMed

Snow, J E

1994-09-01

1. Evaluation of workplace exposure to reproductive hazards is difficult and is often confounded by occupational exposure to multiple agents and exposure to non-occupational factors. 2. A growing body of evidence from animal and human study data supports a causal association between occupational exposure to certain glycol ethers and adverse reproductive outcomes. 3. Occupational health nurses providing services to employees exposed to glycol ethers should remain knowledgeable about the results of epidemiologic studies and current trends in the regulation of glycol ethers in industry. 4. Occupational health nurses are in a key position to reduce exposure to reproductive hazards by monitoring trends in group data and by implementing training and education programs to employees exposed to reproductive hazards.

Neurocognitive function in an extended Afrikaner-ancestry family with affective illness.

PubMed

Savitz, Jonathan; van der Merwe, Lize; Solms, Mark; Ramesar, Rajkumar

2007-03-01

To characterize the neuropsychological profile of an extended family with unipolar depression (UPD) and other forms of affective illness. We administered a battery of neuropsychological tasks measuring various aspects of executive function and visual and verbal memory to 49 individuals in 1 extended family. Six participants had 1 lifetime episode of major depression (MDE-S), 15 were diagnosed with recurrent major depression (MDE-R), 11 had another DSM-IV diagnosis and 17 subjects were unaffected. After controlling for multiple confounding factors, including mood and medication, the MDE-R sample made significantly more errors than unaffected relatives on the Stroop Task, a measure of cognitive control. There may be at least 1 subtype of UPD characterized by a state-independent deficit in cognitive control.

Crash test ratings and real-world frontal crash outcomes: a CIREN study.

PubMed

Ryb, Gabriel E; Burch, Cynthia; Kerns, Timothy; Dischinger, Patricia C; Ho, Shiu

2010-05-01

To establish whether the Insurance Institute for Highway Safety (IIHS) offset crash test ratings are linked to different mortality rates in real world frontal crashes. The study used Crash Injury Research Engineering Network drivers of age older than 15 years who were involved in frontal crashes. The Crash Injury Research Engineering Network is a convenience sample of persons injured in crashes with at least one Abbreviated Injury Scale score of 3+ injury or two Abbreviated Injury Scale score of 2+ injuries who were either treated at a Level I trauma center or died. Cases were grouped by IIHS crash test ratings (i.e., good, acceptable, marginal, poor, and not rated). Those rated marginal were excluded because of their small numbers. Mortality rates experienced by these ratings-based groups were compared using the Mantel-Haenszel chi test. Multiple logistic regression models were built to adjust for confounders (i.e., occupant, vehicular, and crash factors). A total of 1,226 cases were distributed within not rated (59%), poor (12%), average (16%), and good (14%) categories. Those rated good and average experienced a lower unadjusted mortality rate. After adjustment by confounders, those in vehicles rated good experienced a lower risk of death (adjusted OR 0.38 [0.16-0.90]) than those in vehicles rated poor. There was no significant effect for "acceptable" rating. Other factors influencing the occurrence of death were age, DeltaV >or=70 km/h, high body mass index, and lack of restraint use. After adjusting for occupant, vehicular, and crash factors, drivers of vehicles rated good by the IIHS experienced a lower risk of death in frontal crashes.

Can early introduction of egg prevent egg allergy in infants? A population-based study.

PubMed

Koplin, Jennifer J; Osborne, Nicholas J; Wake, Melissa; Martin, Pamela E; Gurrin, Lyle C; Robinson, Marnie N; Tey, Dean; Slaa, Marjolein; Thiele, Leone; Miles, Lucy; Anderson, Deborah; Tan, Tina; Dang, Thanh D; Hill, David J; Lowe, Adrian J; Matheson, Melanie C; Ponsonby, Anne-Louise; Tang, Mimi L K; Dharmage, Shyamali C; Allen, Katrina J

2010-10-01

Infant feeding guidelines have long recommended delaying introduction of solids and allergenic foods to prevent allergy in high-risk infants, despite a paucity of evidence. We aimed to determine whether confirmed egg allergy in 12-month-old infants is associated with (1) duration of breast-feeding and (2) ages of introducing egg and solids. In a population-based cross-sectional study (HealthNuts) parents reported on infant feeding and potential confounding factors before skin prick testing for egg white. Egg-sensitized infants were then offered an egg oral food challenge. Multiple logistic regression was used to investigate associations between diet and egg allergy adjusted for possible confounding factors. A total of 2589 infants (73% response) participated. Compared with introduction at 4 to 6 months, introducing egg into the diet later was associated with higher risks of egg allergy (adjusted odds ratios [ORs], 1.6 [95% CI, 1.0-2.6] and 3.4 [95% CI, 1.8-6.5] for introduction at 10-12 and after 12 months, respectively). These findings persisted even in children without risk factors (OR, 3.3 [95% CI, 1.1-9.9]; 10-12 months). At age 4 to 6 months, first exposure as cooked egg reduced the risk of egg allergy compared with first exposure as egg in baked goods (OR, 0.2 [95% CI, 0.06-0.71]). Duration of breast-feeding and age at introduction of solids were not associated with egg allergy. Introduction of cooked egg at 4 to 6 months of age might protect against egg allergy. Changes in infant feeding guidelines could have a significant effect on childhood egg allergy and possibly food allergy more generally. Copyright © 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Maternal depressive symptoms are negatively associated with child growth and development: Evidence from rural India.

PubMed

Nguyen, Phuong Hong; Friedman, Jed; Kak, Mohini; Menon, Purnima; Alderman, Harold

2018-05-17

Maternal depression has been suggested as a risk factor for both poor child growth and development in many low- and middle-income countries, but the validity of many studies is hindered by small sample sizes, varying cut-offs used in depression diagnostics, and incomplete control of confounding factors. This study examines the association between maternal depressive symptoms (MDSs) and child physical growth and cognitive development in Madhya Pradesh, India, where poverty, malnutrition, and poor mental health coexist. Data were from a baseline household survey (n = 2,934) of a randomized controlled trial assessing an early childhood development programme. Multivariate linear and logistic regression analyses were conducted, adjusting for socio-economic factors to avoid confounding the association of mental health and child outcomes. MDS (measured using the Center for Epidemiologic Studies Short Depression Scale) was categorized as low, medium, and high in 47%, 42%, and 10% of mothers, respectively. The prevalence of child developmental delay ranged from 16% to 27% for various development domains. Compared with children of mothers with low MDS, those of high MDS mothers had lower height-for-age, weight-for-age, and weight-for-height z-scores (0.22, 0.21, and 0.15, respectively), a higher rate of stunting and underweight (~1.5 times), and higher rate of developmental delay (partial adjusted odds ratio ranged from 1.3-1.8 for different development domains and fully adjusted odds ratio = 1.4 for fine motor). Our results-that MDS is significantly associated with both child undernutrition and development delay-add to the call for practical interventions to address maternal depression to simultaneously address multiple outcomes for both women and children. © 2018 The Authors. Maternal & Child Nutrition Published by John Wiley & Sons, Ltd.

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.

Ultrasound Elastography and MR Elastography for Assessing Liver Fibrosis: Part 2, Diagnostic Performance, Confounders, and Future Directions

PubMed Central

Tang, An; Cloutier, Guy; Szeverenyi, Nikolaus M.; Sirlin, Claude B.

2016-01-01

OBJECTIVE The purpose of the article is to review the diagnostic performance of ultrasound and MR elastography techniques for detection and staging of liver fibrosis, the main current clinical applications of elastography in the abdomen. CONCLUSION Technical and instrument-related factors and biologic and patient-related factors may constitute potential confounders of stiffness measurements for assessment of liver fibrosis. Future developments may expand the scope of elastography for monitoring liver fibrosis and predict complications of chronic liver disease. PMID:25905762

Sunny holidays before and after melanoma diagnosis are respectively associated with lower Breslow thickness and lower relapse rates in Italy.

PubMed

Gandini, Sara; De Vries, Esther; Tosti, Giulio; Botteri, Edoardo; Spadola, Giuseppe; Maisonneuve, Patrick; Martinoli, Chiara; Joosse, Arjen; Ferrucci, Pier Francesco; Baldini, Federica; Cocorocchio, Emilia; Pennacchioli, Elisabetta; Cataldo, Francesco; Bazolli, Barbara; Clerici, Alessandra; Barberis, Massimo; Bataille, Veronique; Testori, Alessandro

2013-01-01

Previous studies have reported an association between sun exposure and improved cutaneous melanoma (CM) survival. We analysed the association of UV exposure with prognostic factors and outcome in a large melanoma cohort. A questionnaire was given to 289 (42%) CM patients at diagnosis (Group 1) and to 402 CM patients (58%) during follow-up (Group 2). Analyses were carried out to investigate the associations between sun exposure and melanoma prognostic factors and survival. Holidays in the sun two years before CM diagnosis were significantly associated with lower Breslow thickness (p=0.003), after multiple adjustment. Number of weeks of sunny holidays was also significantly and inversely associated with thickness in a dose-dependent manner (p=0.007). However when stratifying by gender this association was found only among women (p=0.0004) the risk of CM recurrence in both sexes was significantly lower in patients (n=271) who had holidays in the sun after diagnosis, after multiple adjustment including education: HR=0.30 (95%CI:0.10-0.87; p=0.03) conclusions: Holidays in the sun were associated with thinner melanomas in women and reduced rates of relapse in both sexes. However, these results do not prove a direct causal effect of sun exposure on survival since other confounding factors, such as vitamin D serum levels and socio-economic status, may play a role. Other factors in sun seeking individuals may also possibly affect these results.

Sunny Holidays before and after Melanoma Diagnosis Are Respectively Associated with Lower Breslow Thickness and Lower Relapse Rates in Italy

PubMed Central

Gandini, Sara; De Vries, Esther; Tosti, Giulio; Botteri, Edoardo; Spadola, Giuseppe; Maisonneuve, Patrick; Martinoli, Chiara; Joosse, Arjen; Ferrucci, Pier Francesco; Baldini, Federica; Cocorocchio, Emilia; Pennacchioli, Elisabetta; Cataldo, Francesco; Bazolli, Barbara; Clerici, Alessandra; Barberis, Massimo

2013-01-01

Background Previous studies have reported an association between sun exposure and improved cutaneous melanoma (CM) survival. We analysed the association of UV exposure with prognostic factors and outcome in a large melanoma cohort. Methods A questionnaire was given to 289 (42%) CM patients at diagnosis (Group 1) and to 402 CM patients (58%) during follow-up (Group 2). Analyses were carried out to investigate the associations between sun exposure and melanoma prognostic factors and survival. Results Holidays in the sun two years before CM diagnosis were significantly associated with lower Breslow thickness (p=0.003), after multiple adjustment. Number of weeks of sunny holidays was also significantly and inversely associated with thickness in a dose-dependent manner (p=0.007). However when stratifying by gender this association was found only among women (p=0.0004) the risk of CM recurrence in both sexes was significantly lower in patients (n=271) who had holidays in the sun after diagnosis, after multiple adjustment including education: HR=0.30 (95%CI:0.10-0.87; p=0.03) conclusions: Holidays in the sun were associated with thinner melanomas in women and reduced rates of relapse in both sexes. However, these results do not prove a direct causal effect of sun exposure on survival since other confounding factors, such as vitamin D serum levels and socio-economic status, may play a role. Other factors in sun seeking individuals may also possibly affect these results. PMID:24223851

A population-based study on the association between rheumatoid arthritis and voice problems.

PubMed

Hah, J Hun; An, Soo-Youn; Sim, Songyong; Kim, So Young; Oh, Dong Jun; Park, Bumjung; Kim, Sung-Gyun; Choi, Hyo Geun

2016-07-01

The objective of this study was to investigate whether rheumatoid arthritis increases the frequency of organic laryngeal lesions and the subjective voice complaint rate in those with no organic laryngeal lesion. We performed a cross-sectional study using the data from 19,368 participants (418 rheumatoid arthritis patients and 18,950 controls) of the 2008-2011 Korea National Health and Nutrition Examination Survey. The associations between rheumatoid arthritis and organic laryngeal lesions/subjective voice complaints were analyzed using simple/multiple logistic regression analysis with complex sample adjusting for confounding factors, including age, sex, smoking status, stress level, and body mass index, which could provoke voice problems. Vocal nodules, vocal polyp, and vocal palsy were not associated with rheumatoid arthritis in a multiple regression analysis, and only laryngitis showed a positive association (adjusted odds ratio, 1.59; 95 % confidence interval, 1.01-2.52; P = 0.047). Rheumatoid arthritis was associated with subjective voice discomfort in a simple regression analysis, but not in a multiple regression analysis. Participants with rheumatoid arthritis were older, more often female, and had higher stress levels than those without rheumatoid arthritis. These factors were associated with subjective voice complaints in both simple and multiple regression analyses. Rheumatoid arthritis was not associated with organic laryngeal diseases except laryngitis. Rheumatoid arthritis did not increase the odds ratio for subjective voice complaints. Voice problems in participants with rheumatoid arthritis originated from the characteristics of the rheumatoid arthritis group (higher mean age, female sex, and stress level) rather than rheumatoid arthritis itself.

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)

Supervisor Autonomy and Considerate Leadership Style are Associated with Supervisors' Likelihood to Accommodate Back Injured Workers.

PubMed

McGuire, Connor; Kristman, Vicki L; Shaw, William; Williams-Whitt, Kelly; Reguly, Paula; Soklaridis, Sophie

2015-09-01

To determine the association between supervisors' leadership style and autonomy and supervisors' likelihood of supporting job accommodations for back-injured workers. A cross-sectional study of supervisors from Canadian and US employers was conducted using a web-based, self-report questionnaire that included a case vignette of a back-injured worker. Autonomy and two dimensions of leadership style (considerate and initiating structure) were included as exposures. The outcome, supervisors' likeliness to support job accommodation, was measured with the Job Accommodation Scale (JAS). We conducted univariate analyses of all variables and bivariate analyses of the JAS score with each exposure and potential confounding factor. We used multivariable generalized linear models to control for confounding factors. A total of 796 supervisors participated. Considerate leadership style (β = .012; 95% CI .009-.016) and autonomy (β = .066; 95% CI .025-.11) were positively associated with supervisors' likelihood to accommodate after adjusting for appropriate confounding factors. An initiating structure leadership style was not significantly associated with supervisors' likelihood to accommodate (β = .0018; 95% CI -.0026 to .0061) after adjusting for appropriate confounders. Autonomy and a considerate leadership style were positively associated with supervisors' likelihood to accommodate a back-injured worker. Providing supervisors with more autonomy over decisions of accommodation and developing their considerate leadership style may aid in increasing work accommodation for back-injured workers and preventing prolonged work disability.

Integrated presentation of ecological risk from multiple stressors

PubMed Central

Goussen, Benoit; Price, Oliver R.; Rendal, Cecilie; Ashauer, Roman

2016-01-01

Current environmental risk assessments (ERA) do not account explicitly for ecological factors (e.g. species composition, temperature or food availability) and multiple stressors. Assessing mixtures of chemical and ecological stressors is needed as well as accounting for variability in environmental conditions and uncertainty of data and models. Here we propose a novel probabilistic ERA framework to overcome these limitations, which focusses on visualising assessment outcomes by construct-ing and interpreting prevalence plots as a quantitative prediction of risk. Key components include environmental scenarios that integrate exposure and ecology, and ecological modelling of relevant endpoints to assess the effect of a combination of stressors. Our illustrative results demonstrate the importance of regional differences in environmental conditions and the confounding interactions of stressors. Using this framework and prevalence plots provides a risk-based approach that combines risk assessment and risk management in a meaningful way and presents a truly mechanistic alternative to the threshold approach. Even whilst research continues to improve the underlying models and data, regulators and decision makers can already use the framework and prevalence plots. The integration of multiple stressors, environmental conditions and variability makes ERA more relevant and realistic. PMID:27782171

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.

Living near the port area is associated with physical inactivity and sedentary behavior.

PubMed

Sperandio, Evandro Fornias; Arantes, Rodolfo Leite; Chao, Tsai Ping; Romiti, Marcello; Gagliardi, Antônio Ricardo de Toledo; Dourado, Victor Zuniga

2017-01-01

The impact of the port of Santos, Brazil, on the population's health is unknown. We aimed to evaluate the association between living near the port area and physical inactivity and sedentary behavior. Cross-sectional study developed at a university laboratory and a diagnostic clinic. 553 healthy adults were selected and their level of physical activity in daily life was assessed using accelerometers. Multiple linear and logistic regressions were performed using physical inactivity and sedentary behavior as the outcomes and living near the port area as the main risk factor, with adjustments for the main confounders. Among all the participants, 15% were resident near the port area. They took 699 steps/day and presented, weekly, 2.4% more sedentary physical activity, 2.0% less time in standing position and 0.9% more time lying down than residents of other regions. Additionally, living near the port area increased the risk of physical inactivity by 2.50 times and the risk of higher amounts of sedentary behavior (≥ 10 hours/day) by 1.32 times. Living near the port of Santos is associated with physical inactivity and higher sedentary behavior among adults, regardless of confounders. The reasons for this association should be investigated in longitudinal studies.

Is the association between posttraumatic stress disorder symptoms and poor health due to a common familial or genetic factor?

PubMed Central

Roy-Byrne, Peter P.; Noonan, Carolyn; Afari, Niloofar; Buchwald, Dedra; Goldberg, Jack

2010-01-01

Objective The objective of this study was to identify genetic, familial and environmental contributions to the association between posttraumatic stress disorder (PTSD) symptoms and poor health. Methods A community sample of 1852 twin pairs was assessed for symptoms of PTSD [with the Impact of Events Scale (IES)] and self-reported global health status using a single five-level question. An ordinal logistic regression model estimated odds ratio/s (OR) for the association between PTSD and health status. Within-pair analysis assessed confounding by familial and genetic factors and adjusted for the possible confounding influence of age, sex, race, education and self-reported physician diagnosis of depression. Results The IES was strongly and significantly associated with self-reported health [OR = 1.8; 95% confidence interval (95% CI) = 1.5–2.2; highest quartile vs. lowest quartile]. This association remained significant in within-pair analysis (OR = 1.3; 95% CI=1.0–1.7), but after further adjustment for sociodemographics and depression, it was no longer significant (Ptrend=.17). Separate analysis by zygosity did not show differential effect in monozygotic or dizygotic pairs. Conclusion These findings suggest that the association between PTSD symptoms and poor health is, in part, due to familial confounding and sociodemographic factors. Little evidence of confounding by genetic factors was found. These findings suggest that early prevention efforts would have the greatest potential for improving poor health in PTSD-prone patients, whereas later intervention efforts directed at treating PTSD may have a more limited impact on improving poor health. PMID:16950376

Psychosocial well-being and health-related quality of life in a UK population with Usher syndrome.

PubMed

Dean, Gavin; Orford, Amy; Staines, Roy; McGee, Anna; Smith, Kimberley J

2017-01-12

To determine whether psychosocial well-being is associated with the health-related quality of life (HRQOL) of people with Usher syndrome. The survey was advertised online and through deafblind-related charities, support groups and social groups throughout the UK. 90 people with Usher syndrome took part in the survey. Inclusion criteria are having a diagnosis of Usher syndrome, being 18 or older and being a UK resident. All participants took part in a survey that measured depressive symptoms, loneliness and social support (predictors) and their physical and mental HRQOL (outcomes). Measured confounders included age-related, sex-related and health-related characteristics. Hierarchical multiple linear regression analyses examined the association of each psychosocial well-being predictor with the physical and mental HRQOL outcomes while controlling for confounders in a stepwise manner. After adjusting for all confounders, psychosocial well-being was shown to predict physical and mental HRQOL in our population with Usher syndrome. Increasing depressive symptoms were predictive of poorer physical (β=-0.36, p<0.01) and mental (β=-0.60, p<0.001) HRQOL. Higher levels of loneliness predicted poorer mental HRQOL (β=-0.20, p<0.05). Finally, increasing levels of social support predicted better mental HRQOL (β=0.19, p<0.05). Depression, loneliness and social support all represent important issues that are linked with HRQOL in a UK population with Usher syndrome. Our results add to the growing body of evidence that psychosocial well-being is an important factor to consider in people with Usher syndrome alongside functional and physical impairment within research and clinical practice. 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/.

Low testosterone and non-alcoholic fatty liver disease: Evidence for their independent association in men with chronic spinal cord injury.

PubMed

Barbonetti, Arcangelo; Caterina Vassallo, Maria Rosaria; Cotugno, Michele; Felzani, Giorgio; Francavilla, Sandro; Francavilla, Felice

2016-07-01

Non-alcoholic fatty liver disease (NAFLD) has been claimed as a liver phenotype of metabolic syndrome, which in turn is associated with male hypogonadism. We assessed whether an independent association between NAFLD and androgen deficiency could be revealed in men with chronic spinal cord injury (SCI), who exhibit a high prevalence of biochemical androgen deficiency and a combination of risk factors for metabolic syndrome. Fifty-five consecutive men with chronic SCI admitted to a rehabilitation program underwent clinical/biochemical evaluations and liver ultrasonography. NAFLD was diagnosed in 27 patients (49.1%). Men with NAFLD were older and exhibited significantly higher body mass index, Homeostatic model assessment of insulin resistance, triglycerides and gamma-glutamyl transpeptidase values, lower total and free testosterone levels and they were engaged in a significantly poorer weekly leisure time physical activity (LTPA). At the multiple logistic regression analysis, only total and free testosterone levels exhibited a significant independent association with NAFLD. The risk of having NAFLD increased indeed of 1% for each decrement of 1 ng/dL of total testosterone and of 3% for each decrement of 1 pg/mL of free testosterone, after adjustment for confounders. In men with total testosterone < 300 ng/dL (36.4%) the prevalence of NAFLD reached 85%: they had a risk of having NAFLD significantly higher (∼12-fold) than those with total testosterone ≥ 300 ng/dL, after adjustment for confounders. The evidence of an independent association between NAFLD and low testosterone is strongly reinforced by its demonstration in men with chronic SCI, in spite of the many confounders peculiar to this population.

Thyroid status and 6-year mortality in elderly people living in a mildly iodine-deficient area: the aging in the Chianti Area Study.

PubMed

Ceresini, Graziano; Ceda, Gian Paolo; Lauretani, Fulvio; Maggio, Marcello; Usberti, Elisa; Marina, Michela; Bandinelli, Stefania; Guralnik, Jack M; Valenti, Giorgio; Ferrucci, Luigi

2013-06-01

To test the hypothesis that, in older adults, living in a mildly iodine-deficient area, thyroid dysfunction may be associated with mortality independent of potential confounders. Longitudinal. Community-based. Nine hundred fifty-one individuals aged 65 and older. Plasma thyrotropin, free thyroxine, and free triiodothyronine concentrations and demographic features were evaluated in participants of the Invecchiare in Chianti Study aged 65 and older. Participants were classified according to thyroid function test. Kaplan-Meier survival and Cox proportional hazards models adjusted for confounders were used in the analysis. Eight hundred nineteen participants were euthyroid, 83 had subclinical hyperthyroidism (SHyper), and 29 had subclinical hypothyroidism (SHypo). Overt hypo- and hyperthyroidism were found in five and 15 subjects, respectively. During a median of 6 years of follow-up, 210 deaths occurred (22.1%), 98 (46.6%) of which were from cardiovascular causes. Kaplan-Meier analysis revealed higher overall mortality for SHyper (P = .04) than euthyroid subjects. After adjusting for multiple confounders, participants with SHyper (hazard ratio (HR) = 1.65, 95% confidence interval (CI) = 1.02-2.69) had significantly higher all-cause mortality than those with normal thyroid function. No significant association was found between SHyper and cardiovascular mortality. In euthyroid subjects, thyrotropin was found to be predictive of lower risk of all-cause mortality (HR = 0.76, 95% CI = 0.57-0.99). SHyper is an independent risk factor for all-cause mortality in older adults. Low to normal circulating thyrotropin should be carefully monitored in elderly euthyroid individuals. © 2013, Copyright the Authors Journal compilation © 2013, The American Geriatrics Society.

Psychosocial well-being and health-related quality of life in a UK population with Usher syndrome

PubMed Central

Dean, Gavin; Orford, Amy; Staines, Roy; McGee, Anna; Smith, Kimberley J

2017-01-01

Objectives To determine whether psychosocial well-being is associated with the health-related quality of life (HRQOL) of people with Usher syndrome. Setting The survey was advertised online and through deafblind-related charities, support groups and social groups throughout the UK. Participants 90 people with Usher syndrome took part in the survey. Inclusion criteria are having a diagnosis of Usher syndrome, being 18 or older and being a UK resident. Primary and secondary outcome measures All participants took part in a survey that measured depressive symptoms, loneliness and social support (predictors) and their physical and mental HRQOL (outcomes). Measured confounders included age-related, sex-related and health-related characteristics. Hierarchical multiple linear regression analyses examined the association of each psychosocial well-being predictor with the physical and mental HRQOL outcomes while controlling for confounders in a stepwise manner. Results After adjusting for all confounders, psychosocial well-being was shown to predict physical and mental HRQOL in our population with Usher syndrome. Increasing depressive symptoms were predictive of poorer physical (β=−0.36, p<0.01) and mental (β=−0.60, p<0.001) HRQOL. Higher levels of loneliness predicted poorer mental HRQOL (β=−0.20, p<0.05). Finally, increasing levels of social support predicted better mental HRQOL (β=0.19, p<0.05). Conclusions Depression, loneliness and social support all represent important issues that are linked with HRQOL in a UK population with Usher syndrome. Our results add to the growing body of evidence that psychosocial well-being is an important factor to consider in people with Usher syndrome alongside functional and physical impairment within research and clinical practice. PMID:28082366

Malignant Tumors of the Female Reproductive System

PubMed Central

Labrèche, France

2012-01-01

This review summarizes the epidemiology of cancer of the female reproductive system and associated lifestyle factors. It also assesses the available evidence for occupational factors associated with these cancers. Cervical, endometrial, and ovarian cancers are relatively common, and cause significant cancer morbidity and mortality worldwide, whereas vulvar, vaginal, fallopian tube cancers, and choriocarcinomas are very rare. As several lifestyle factors are known to play a major role in the etiology of these cancers, very few published studies have investigated possible relationships with occupational factors. Some occupational exposures have been associated with increased risks of these cancers, but apart from the available evidence on the relationships between asbestos fibers and ovarian cancer, and tetrachloroethylene and cervical cancer, the data is rather scarce. Given the multifactorial nature of cancers of the female reproductive system, it is of the utmost importance to conduct occupational studies that will gather detailed data on potential individual confounding factors, in particular reproductive history and other factors that influence the body's hormonal environment, together with information on socio-economic status and lifestyle factors, including physical activity from multiple sources. Studies on the mechanisms of carcinogenesis in the female reproductive organs are also needed in order to elucidate the possible role of chemical exposures in the development of these cancers. PMID:23019529

A longitudinal comparative study of falls in persons with knee arthroplasty and persons with or at high risk for knee osteoarthritis.

PubMed

L Riddle, Daniel; J Golladay, Gregory

2016-11-01

we determined the yearly prevalence of single and multiple falls in persons with or at risk of knee osteoarthritis (OA) and persons undergoing knee arthroplasty over an 8-year period. We also compared annual fall rates among persons with and without knee arthroplasty to determine if fall rates are associated with knee arthroplasty. we studied 4,200 persons from the Osteoarthritis Imitative (OAI), a National Institutes of Health funded prospective study of persons 45-79 years and conducted from 2004 to 2012. All either had knee OA or were at risk of developing knee OA but did not have knee arthroplasty. The surgical group comprised 413 persons who underwent knee arthroplasty. Key fall risk factors were assessed at yearly study visits. Graphical depictions illustrated single and multiple fall trajectories. Multinomial regression adjusted for potential confounders compared fall rates for those with and without knee arthroplasty. fall rate trajectories for the two samples were generally flat and fall rates were similar. For the arthroplasty sample, fall rates did not increase in the immediate perioperative period relative to earlier and later periods. No differences in fall rates were found among the arthroplasty and non-arthroplasty samples after adjustment for potential confounding (P > 0.05). fall rates were generally stable and similar over an 8-year period among persons with and without knee arthroplasty. Clinicians should not assume that persons undergoing knee arthroplasty are at greater risk for falls either before or after surgery as compared to persons with or at risk for knee OA. © 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.

Long-term pediatric skin eruption-related hospitalizations in offspring conceived via fertility treatment.

PubMed

Krieger, Yuval; Wainstock, Tamar; Sheiner, Eyal; Harlev, Avi; Landau, Daniella; Horev, Amir; Bogdanov-Berezovsky, Alexander; Walfisch, Asnat

2018-03-01

Although concerns have been raised regarding the long-term health risks of offspring conceived following fertility treatments, limited information is available regarding their health status beyond the neonatal period. We aimed to evaluate the risk of long-term eruptive dermatological morbidity among children born following fertility treatments as compared to those conceived spontaneously. A population-based cohort study was conducted, including all singleton deliveries occurring between the years 1991 and 2014 at a single tertiary medical center. Fetuses with congenital malformations and multiple gestations were excluded. Children delivered following fertility treatment pregnancies and spontaneous pregnancies were compared. Hospitalizations of the offspring up to the age of 18 years involving cutaneous eruptions were evaluated. A Kaplan-Meier survival curve was used to compare cumulative morbidity incidence and a Cox regression model to control for confounders. During the study period, 242,187 singleton deliveries met the inclusion criteria, 1.8% of which were following fertility treatments (n = 4324). Eruptive dermatological morbidity of the offspring up to the age of 18 years was significantly more common in the fertility treatment group (1.5%) as compared to spontaneous pregnancies (1.1%; P = 0.023). The Kaplan-Meier survival curve demonstrated a significantly higher cumulative incidence of eruptive dermatological morbidity following fertility treatments (log-rank P = 0.007). Using the Cox regression model, while controlling for multiple confounders, fertility treatment was noted as an independent risk factor for long-term pediatric eruptive dermatological morbidity (adjusted HR = 1.43, CI 1.12-1.83, P = 0.004). Singletons conceived via fertility treatments appear to be at an increased risk for long-term eruptive dermatological morbidity. © 2018 The International Society of Dermatology.

Disentangling the developmental trajectories of letter position and letter identity coding using masked priming.

PubMed

Kezilas, Yvette; McKague, Meredith; Kohnen, Saskia; Badcock, Nicholas A; Castles, Anne

2017-02-01

Masked transposed-letter (TL) priming effects have been used to index letter position processing over the course of reading development. Whereas some studies have reported an increase in TL priming over development, others have reported a decrease. These findings have led to the development of 2 somewhat contradictory accounts of letter position development: the lexical tuning hypothesis and the multiple-route model. One factor that may be contributing to these discrepancies is the use of baseline primes that substitute letters in the target word, which may confound the effect of changes in letter position processing over development with those of letter identity. The present study included an identity prime (e.g., listen-LISTEN), in addition to the standard two-substituted-letter (2SL; e.g., lidfen-LISTEN) and all-letter-different (ALD; e.g., rodfup-LISTEN) baselines, to remove the potential confound between letter position and letter identity information in determining the effect of the TL prime. Priming effects were measured in a lexical decision task administered to children aged 7-12 and a group of university students. Using inverse transformed response times, targets preceded by a TL prime were responded to significantly faster than those preceded by 2SL and ALD primes, and priming remained stable across development. In contrast, targets preceded by a TL prime were responded to significantly slower than those preceded by an ID prime, and this reaction-time cost increased significantly over development, with adults showing the largest cost. These findings are consistent with a lexical tuning account of letter position development, and are inconsistent with the multiple-route model. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

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.

Housing Instability and Children's Health Insurance Gaps.

PubMed

Carroll, Anne; Corman, Hope; Curtis, Marah A; Noonan, Kelly; Reichman, Nancy E

To assess the extent to which housing instability is associated with gaps in health insurance coverage of preschool-age children. Secondary analysis of data from the Early Childhood Longitudinal Study-Birth Cohort, a nationally representative study of children born in the United States in 2001, was conducted to investigate associations between unstable housing-homelessness, multiple moves, or living with others and not paying rent-and children's subsequent health insurance gaps. Logistic regression was used to adjust for potentially confounding factors. Ten percent of children were unstably housed at age 2, and 11% had a gap in health insurance between ages 2 and 4. Unstably housed children were more likely to have gaps in insurance compared to stably housed children (16% vs 10%). Controlling for potentially confounding factors, the odds of a child insurance gap were significantly higher in unstably housed families than in stably housed families (adjusted odds ratio 1.27; 95% confidence interval 1.01-1.61). The association was similar in alternative model specifications. In a US nationally representative birth cohort, children who were unstably housed at age 2 were at higher risk, compared to their stably housed counterparts, of experiencing health insurance gaps between ages 2 and 4 years. The findings from this study suggest that policy efforts to delink health insurance renewal processes from mailing addresses, and potentially routine screenings for housing instability as well as referrals to appropriate resources by pediatricians, would help unstably housed children maintain health insurance. Copyright © 2017 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Infant developmental milestones and adult intelligence: A 34-year follow-up.

PubMed

Flensborg-Madsen, Trine; Mortensen, Erik Lykke

2015-07-01

A number of studies suggest a positive association between faster infant motor development and intellectual function in childhood and adolescence. However, studies investigating the relationship between infant motor development and intelligence in adulthood are lacking. To investigate whether age at achievement of 12 motor developmental milestones was associated with adult intelligence and to evaluate the influence of sex, parental social status, parity, mother's cigarette consumption in the last trimester, gestational age, birthweight, and birth length on this association. Mothers of 9125 children of the Copenhagen Perinatal Cohort recorded 12 developmental milestones during the child's first year of life. A subsample of the cohort comprising 1155 individuals participated in a follow-up when they were aged 20-34 years and were administered the Wechsler Adult Intelligence Scale (WAIS). Associations between motor developmental milestones and IQ were analysed by multiple linear regression adjusting for potential confounding factors. Later acquisition of infant developmental milestones was associated with lower subsequent IQ, and the majority of significant associations were found for Performance IQ. Correlations were generally small (r < 0.10), but significant interactions were found between parental social status and age of attaining developmental milestones, with associations being significantly stronger in the offspring of lower social status parents. The effects remained significant after adjusting for possible confounding factors. This is the first study to find significant interactions with parental social status, thereby suggesting that associations between early motor development and intelligence are stronger in infants of low social status parents. Copyright © 2015 Elsevier B.V. All rights reserved.

Emesis as a Screening Diagnostic for Low Dose Rate (LDR) Total Body Radiation Exposure.

PubMed

Camarata, Andrew S; Switchenko, Jeffrey M; Demidenko, Eugene; Flood, Ann B; Swartz, Harold M; Ali, Arif N

2016-04-01

Current radiation disaster manuals list the time-to-emesis (TE) as the key triage indicator of radiation dose. The data used to support TE recommendations were derived primarily from nearly instantaneous, high dose-rate exposures as part of variable condition accident databases. To date, there has not been a systematic differentiation between triage dose estimates associated with high and low dose rate (LDR) exposures, even though it is likely that after a nuclear detonation or radiologic disaster, many surviving casualties would have received a significant portion of their total exposure from fallout (LDR exposure) rather than from the initial nuclear detonation or criticality event (high dose rate exposure). This commentary discusses the issues surrounding the use of emesis as a screening diagnostic for radiation dose after LDR exposure. As part of this discussion, previously published clinical data on emesis after LDR total body irradiation (TBI) is statistically re-analyzed as an illustration of the complexity of the issue and confounding factors. This previously published data includes 107 patients who underwent TBI up to 10.5 Gy in a single fraction delivered over several hours at 0.02 to 0.04 Gy min. Estimates based on these data for the sensitivity of emesis as a screening diagnostic for the low dose rate radiation exposure range from 57.1% to 76.6%, and the estimates for specificity range from 87.5% to 99.4%. Though the original data contain multiple confounding factors, the evidence regarding sensitivity suggests that emesis appears to be quite poor as a medical screening diagnostic for LDR exposures.

Association between long working hours and sleep problems in white-collar workers.

PubMed

Nakashima, Motoko; Morikawa, Yuko; Sakurai, Masaru; Nakamura, Koshi; Miura, Katsuyuki; Ishizaki, Masao; Kido, Teruhiko; Naruse, Yuchi; Suwazono, Yasushi; Nakagawa, Hideaki

2011-03-01

The purpose of this study is to examine the association between long work hours and sleep disturbance among white-collar workers. We evaluated 1510 male white-collar full-time employees, between the ages of 18 and 59 years, using a comprehensive sleep quality questionnaire, the Pittsburgh Sleep Quality Index (PSQI). All subjects worked in a light metal products factory in Japan. The mean number of monthly overtime work hours was determined using data from the previous 6 months from timecard records. Subjects were divided into five groups based on quintiles of the mean number of monthly overtime work hours: <26 h month(-1); ≥26 but <40; ≥40 but <50; ≥50 but <63; and >63. Leisure time physical activity, drinking habits just before sleep, presence of family/partner and health status were used as confounding factors in the multiple regression model. The prevalence of short sleep hours, impairment of sleep efficiency and daytime dysfunction among seven components of PSQI increased, in a dose-response relationship, with overtime work hours. The prevalence of high global score (>5.5 points) was highest in workers with overtime hours ≥50 h week(-1). The odds ratios after adjustment for confounding factors for high global score using less than 26 h as a reference group were 1.67 for workers with ≥50 h and <63 h, and 1.87 for workers with 63 h and more. To conclude, the present results suggest that long work hours correlate with reduced sleep quality in a dose-response manner. © 2010 European Sleep Research Society.

Plasma lipid peroxidation and erythrocyte antioxidant enzymes status in workers exposed to cadmium.

PubMed

Babu, Kalahasthi Ravi; Rajmohan, Hirehal Raghavendra Rao; Rajan, Bagalur Krishna Murthy; Kumar, Karuna M

2006-09-01

Cadmium (Cd) is a corrosion-resistant metal, used extensively for electroplating in the automobile, electronic and aerospace industry. Only a few studies are available regarding Cd-induced oxidative stress in animals, but no reports are available regarding the effects of Cd on oxidative stress during occupational exposure. The present study was carried out to determine the plasma lipid peroxidation and erythrocyte antioxidant enzymes status in workers exposed to Cd during electroplating. 50 subjects exposed to Cd during electroplating formed the study group. An equal number of age-sex matched subjects, working in the administrative section, formed the control group. Urinary Cd levels were determined using the flameless atomic absorption spectrophotometer. Plasma lipid peroxidation and erythrocyte antioxidant enzymes were determined using spectrophotometric methods. A significant increase of plasma lipid peroxidation and a significant decrease of superoxide dismutase and glutathione peroxidase levels were noted in the study group compared with the control group. The level of plasma lipid peroxidation was positively and erythrocyte antioxidant enzymes were negatively and significantly associated with Cd levels in urine. Multiple regression analysis assessed the oxidative stress associated with Cd and other lifestyle confounding factors, such as age, body mass index, the consumption of vegetables, coffee, tea, smoking and alcohol. Analysis showed that the lifestyle confounding factors viz; smoking, body mass index and urinary Cd levels > 5 microg/g of creatinine, were significantly associated with oxidative stress. The results of the present study suggest that increased plasma lipid peroxidation and decreased superoxide dismutase levels could be used as biomarkers of oxidative stress in cadmium-exposed workers.

Use of erythrocyte indicators of health and condition in vertebrate ecophysiology: a review and appraisal.

PubMed

Johnstone, Christopher P; Lill, Alan; Reina, Richard D

2017-02-01

We review evidence for and against the use of erythrocyte indicators of health status and condition, parasite infection level and physiological stress in free-living vertebrates. The use of indicators that are measured directly from the blood, such as haemoglobin concentration, haematocrit and erythrocyte sedimentation rate, and parameters that are calculated from multiple measured metrics, such as mean cell volume, mean cell haemoglobin content or mean cell haemoglobin concentration is evaluated. The evidence for or against the use of any given metric is equivocal when the relevant research is considered in total, although there is sometimes strong support for using a particular metric in a particular taxon. Possibly the usefulness of these metrics is taxon, environment or condition specific. Alternatively, in an uncontrolled environment where multiple factors are influencing a metric, its response to environmental change will sometimes, but not always, be predictable. We suggest that (i) researchers should validate a metricfres utility before use, (ii) multiple metrics should be used to construct an overall erythrocyte profile for an individual or population, (iii) there is a need for researchers to compile reference ranges for free-living species, and (iv) some metrics which are useful under controlled, clinical conditions may not have the same utility or applicability for free-living vertebrates. Erythrocyte metrics provide useful information about health and condition that can be meaningfully interpreted in free-living vertebrates, but their use requires careful forethought about confounding factors. © 2015 Cambridge Philosophical Society.

A multi-level analysis of risk perception, poverty and sexual risk-taking among young people in Cape Town, South Africa.

PubMed

Tenkorang, Eric Y; Maticka-Tyndale, Eleanor; Rajulton, Fernando

2011-03-01

Various studies have underscored the relevance of community-level factors to sexual behavior and HIV/AIDS prevention efforts in Africa. However, there is a paucity of research and theorizing in this area compared to the preponderance of prevention models that focus solely on individual-level factors. Using data from the Cape Area Panel Survey and hierarchical linear models, this study examines the effects of a combination of individual-level factors and community-level poverty on sexual behaviors. Male and female respondents who perceived themselves to be at great risk of HIV infection were less likely to indulge in risky sexual behaviors. For females, race and community-level poverty were confounded such that race mediated the effects of community-level poverty. Results from this study indicate that multiple rationalities affect sexual behaviors in Cape Town, South Africa and that there is a need to consider both the social embeddedness of sexual behaviors and the rational components of decision making when designing HIV/AIDS prevention programs. Copyright © 2010 Elsevier Ltd. All rights reserved.

Combining matched and unmatched control groups in case-control studies.

PubMed

le Cessie, Saskia; Nagelkerke, Nico; Rosendaal, Frits R; van Stralen, Karlijn J; Pomp, Elisabeth R; van Houwelingen, Hans C

2008-11-15

Multiple control groups in case-control studies are used to control for different sources of confounding. For example, cases can be contrasted with matched controls to adjust for multiple genetic or unknown lifestyle factors and simultaneously contrasted with an unmatched population-based control group. Inclusion of different control groups for a single exposure analysis yields several estimates of the odds ratio, all using only part of the data. Here the authors introduce an easy way to combine odds ratios from several case-control analyses with the same cases. The approach is based upon methods used for meta-analysis but takes into account the fact that the same cases are used and that the estimated odds ratios are therefore correlated. Two ways of estimating this correlation are discussed: sandwich methodology and the bootstrap. Confidence intervals for the pooled estimates and a test for checking whether the odds ratios in the separate case-control studies differ significantly are derived. The performance of the method is studied by simulation and by applying the methods to a large study on risk factors for thrombosis, the MEGA Study (1999-2004), wherein cases with first venous thrombosis were included with a matched control group of partners and an unmatched population-based control group.

The evolution of primate general and cultural intelligence

PubMed Central

Reader, Simon M.; Hager, Yfke; Laland, Kevin N.

2011-01-01

There are consistent individual differences in human intelligence, attributable to a single ‘general intelligence’ factor, g. The evolutionary basis of g and its links to social learning and culture remain controversial. Conflicting hypotheses regard primate cognition as divided into specialized, independently evolving modules versus a single general process. To assess how processes underlying culture relate to one another and other cognitive capacities, we compiled ecologically relevant cognitive measures from multiple domains, namely reported incidences of behavioural innovation, social learning, tool use, extractive foraging and tactical deception, in 62 primate species. All exhibited strong positive associations in principal component and factor analyses, after statistically controlling for multiple potential confounds. This highly correlated composite of cognitive traits suggests social, technical and ecological abilities have coevolved in primates, indicative of an across-species general intelligence that includes elements of cultural intelligence. Our composite species-level measure of general intelligence, ‘primate gS’, covaried with both brain volume and captive learning performance measures. Our findings question the independence of cognitive traits and do not support ‘massive modularity’ in primate cognition, nor an exclusively social model of primate intelligence. High general intelligence has independently evolved at least four times, with convergent evolution in capuchins, baboons, macaques and great apes. PMID:21357224

Cascaded discrimination of normal, abnormal, and confounder classes in histopathology: Gleason grading of prostate cancer

PubMed Central

2012-01-01

Background Automated classification of histopathology involves identification of multiple classes, including benign, cancerous, and confounder categories. The confounder tissue classes can often mimic and share attributes with both the diseased and normal tissue classes, and can be particularly difficult to identify, both manually and by automated classifiers. In the case of prostate cancer, they may be several confounding tissue types present in a biopsy sample, posing as major sources of diagnostic error for pathologists. Two common multi-class approaches are one-shot classification (OSC), where all classes are identified simultaneously, and one-versus-all (OVA), where a “target” class is distinguished from all “non-target” classes. OSC is typically unable to handle discrimination of classes of varying similarity (e.g. with images of prostate atrophy and high grade cancer), while OVA forces several heterogeneous classes into a single “non-target” class. In this work, we present a cascaded (CAS) approach to classifying prostate biopsy tissue samples, where images from different classes are grouped to maximize intra-group homogeneity while maximizing inter-group heterogeneity. Results We apply the CAS approach to categorize 2000 tissue samples taken from 214 patient studies into seven classes: epithelium, stroma, atrophy, prostatic intraepithelial neoplasia (PIN), and prostate cancer Gleason grades 3, 4, and 5. A series of increasingly granular binary classifiers are used to split the different tissue classes until the images have been categorized into a single unique class. Our automatically-extracted image feature set includes architectural features based on location of the nuclei within the tissue sample as well as texture features extracted on a per-pixel level. The CAS strategy yields a positive predictive value (PPV) of 0.86 in classifying the 2000 tissue images into one of 7 classes, compared with the OVA (0.77 PPV) and OSC approaches (0.76 PPV). Conclusions Use of the CAS strategy increases the PPV for a multi-category classification system over two common alternative strategies. In classification problems such as histopathology, where multiple class groups exist with varying degrees of heterogeneity, the CAS system can intelligently assign class labels to objects by performing multiple binary classifications according to domain knowledge. PMID:23110677

[Evaluative designs in public health: methodological considerations].

PubMed

López, Ma José; Marí-Dell'Olmo, Marc; Pérez-Giménez, Anna; Nebot, Manel

2011-06-01

Evaluation of public health interventions poses numerous methodological challenges. Randomization of individuals is not always feasible and interventions are usually composed of multiple factors. To face these challenges, certain elements, such as the selection of the most appropriate design and the use of a statistical analysis that includes potential confounders, are essential. The objective of this article was to describe the most frequently used designs in the evaluation of public health interventions (policies, programs or campaigns). The characteristics, strengths and weaknesses of each of these evaluative designs are described. Additionally, a brief explanation of the most commonly used statistical analysis in each of these designs is provided. Copyright © 2011 Sociedad Española de Salud Pública y Administración Sanitaria. Published by Elsevier Espana. All rights reserved.

Enacting relationships in marriage and family therapy: a conceptual and operational definition of an enactment.

PubMed

Davis, Sean D; Butler, Mark H

2004-07-01

Enactments are a potential common clinical process factor contributing to positive outcomes in many relational therapies. Enactments provide therapists a medium for mediating relationships through simultaneous experiential intervention and change at multiple levels of relationships--including specific relationship disagreements and problems, interaction process surrounding these issues, and underlying emotions and attachment issues confounded with those problems. We propose a model of enactments in marriage and family therapy, consisting of three components--initiation operations, intervention operations, and evaluation operations. We offer a conceptual framework to help clinicians know when and to what purpose to use this model of enactments. We provide an operational description of each component of an enactment, exemplifying them using a hypothetical clinical vignette. Directions for future research are suggested.

Neurocognitive function in an extended Afrikaner-ancestry family with affective illness

PubMed Central

Savitz, Jonathan; van der Merwe, Lize; Solms, Mark; Ramesar, Rajkumar

2007-01-01

Objective To characterize the neuropsychological profile of an extended family with unipolar depression (UPD) and other forms of affective illness. Method We administered a battery of neuropsychological tasks measuring various aspects of executive function and visual and verbal memory to 49 individuals in 1 extended family. Six participants had 1 lifetime episode of major depression (MDE-S), 15 were diagnosed with recurrent major depression (MDE-R), 11 had another DSM-IV diagnosis and 17 subjects were unaffected. Results After controlling for multiple confounding factors, including mood and medication, the MDE-R sample made significantly more errors than unaffected relatives on the Stroop Task, a measure of cognitive control. Conclusion There may be at least 1 subtype of UPD characterized by a state-independent deficit in cognitive control. PMID:17353940

Physiological correlates of mental workload

NASA Technical Reports Server (NTRS)

Zacharias, G. L.

1980-01-01

A literature review was conducted to assess the basis of and techniques for physiological assessment of mental workload. The study findings reviewed had shortcomings involving one or more of the following basic problems: (1) physiologic arousal can be easily driven by nonworkload factors, confounding any proposed metric; (2) the profound absence of underlying physiologic models has promulgated a multiplicity of seemingly arbitrary signal processing techniques; (3) the unspecified multidimensional nature of physiological "state" has given rise to a broad spectrum of competing noncommensurate metrics; and (4) the lack of an adequate definition of workload compels physiologic correlations to suffer either from the vagueness of implicit workload measures or from the variance of explicit subjective assessments. Using specific studies as examples, two basic signal processing/data reduction techniques in current use, time and ensemble averaging are discussed.

Blood pressure and neuropsychological test performance in healthy postmenopausal women.

PubMed

Alsumali, Adnan; Mekary, Rania A; Seeger, John; Regestein, Quentin

2016-06-01

To study the association between blood pressure and neuropsychological test performance in healthy postmenopausal women. Data from 88 healthy postmenopausal women aged 46-73 years, who were not experiencing hot flashes, and who had participated in a prior drug trial, were analyzed to find whether baseline blood pressure was associated with impaired performance on neuropsychological testing done at 3 follow-up visits separated by 4 weeks. Factor analysis was used to reduce the dimensions of neuropsychological test performance. Mixed linear modeling was used to evaluate the association between baseline blood pressure and repeatedly measured neuropsychological test performance at follow-up in a complete case analysis (n=53). In a sensitivity analysis (n=88), multiple-imputation using the Markov Chain Monte Carlo method was used to account for missing data (blood pressure results) for some visits. The variables recording neuropsychological test performance were reduced to two main factors (Factor 1=selective attention; Factor 2=complex processing). In the complete case analysis, the association between a 20-mmHg increase in diastolic blood pressure and Factor 1 remained statistically significant after adjusting for potential confounders, before adjusting for systolic blood pressure (slope=0.60; 95%CI=0.04,1.16), and after adjusting for systolic blood pressure (slope=0.76; 95%CI=0.06, 1.47). The positive slopes indicated an increase in the time spent performing a given task (i.e., a decrease in neuropsychological test performance). No other significant associations were found between systolic blood pressure and either factor. The results did not materially change after applying the multiple-imputation method. An increase in diastolic blood pressure was associated with a decrease in neuropsychological test performance among older healthy postmenopausal women experiencing hot flashes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Homogenization of vegetation structure across residential neighborhoods: effects of climate, urban morphology, and socio-economics

EPA Science Inventory

Climate is a key driver regulating vegetation structure across rural ecosystems. In urban ecosystems, multiple interactions between humans and the environment can have homogenizing influences, confounding the relationship between vegetation structure and climate. In fact, vegetat...

Lumbar disc degeneration was not related to spine and hip bone mineral densities in Chinese: facet joint osteoarthritis may confound the association.

PubMed

Pan, Jianjiang; Lu, Xuan; Yang, Ge; Han, Yongmei; Tong, Xiang; Wang, Yue

2017-12-01

A sample of 512 Chinese was studied and we observed that greater disc degeneration on MRI was associated with greater spine DXA BMD. Yet, this association may be confounded by facet joint osteoarthritis. BMD may not be a risk factor for lumbar disc degeneration in Chinese. Evidence suggested that lumbar vertebral bone and intervertebral disc interact with each other in multiple ways. The current paper aims to determine the association between bone mineral density (BMD) and lumbar disc degeneration using a sample of Chinese. We studied 165 patients with back disorders and 347 general subjects from China. All subjects had lumbar spine magnetic resonance (MR) imaging and dual- energy X-ray absorptiometry (DXA) spine BMD studies, and a subset of general subjects had additional hip BMD measurements. On T2-weighted MR images, Pfirrmann score was used to evaluate the degree of lumbar disc degeneration and facet joint osteoarthritis was assessed as none, slight-moderate, and severe. Regression analyses were used to examine the associations between lumbar and hip BMD and disc degeneration, adjusting for age, gender, body mass index (BMI), lumbar region, and facet joint osteoarthritis. Greater facet joint osteoarthritis was associated with greater spine BMD (P < 0.01) in both patients and general subjects. For general subjects, greater spine BMD was associated with severe disc degeneration, controlling for age, gender, BMI, and lumbar region. When facet joint osteoarthritis entered the regression model, however, greater spine BMD was associated with greater facet joint osteoarthritis (P < 0.01) but not greater disc degeneration (P > 0.05). No statistical association was observed between spine BMD and lumbar disc degeneration in patients with back disorders (P > 0.05), and between hip BMD and disc degeneration in general subjects (P > 0.05). BMD may not be a risk factor for lumbar disc degeneration in Chinese. Facet joint osteoarthritis inflates DXA spine BMD measurements and therefore, may confound the association between spine BMD and disc degeneration.

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.

Estrogen Receptor 1 ( ESR1) Gene Polymorphisms and Obesity Phenotypes in a Population of Young Adults.

PubMed

Correa-Rodríguez, María; Schmidt-RioValle, Jacqueline; González-Jiménez, Emilio; Rueda-Medina, Blanca

2017-06-01

Obesity is considered an increasingly serious health problem determined by multiple genetic and environmental factors. Estrogens have been found to play a major role in body weight and adiposity regulation through estrogen receptor 1 ( ESR1). The aim of this study was to determine whether genotype and haplotype frequencies of ESR1 polymorphisms are associated with body composition measures in a population of 572 young adults. A lack of significant association between genotypes of ESR1 gene polymorphisms and obesity phenotypes was seen after adjustment for confounding factors. Linkage disequilibrium (LD) analysis identified a single LD block for the ESR1 gene including PvuII and XbaI single-nucleotide polymorphisms (SNPs) (pairwise r 2 = .66). None of the haplotypes identified revealed statistically significant associations with any of the obesity phenotypes. Our results suggest that polymorphisms of the ESR1 gene do not contribute significantly to the genetic risk for obesity phenotypes in a population of young Caucasian adults.

Bullying Victimization Among Chinese Middle School Students: The Role of Family Violence.

PubMed

Zhu, Yuhong; Chan, Ko Ling; Chen, Jinsong

2018-06-01

This study used the data from a representative sample to investigate the association between family violence (FV) and child bullying victimization (BV) in Xi'an city, China. Data on social demographic information and the prevalence of BV and FV were collected from a randomly selected sample with 3,175 middle school students aged 15 to 17 by self-administrated questionnaires. Results show that 55.9% and 30.3% of the participants have witnessed intimate partner violence (IPV), 37.7% and 30.8% have been victims of child abuse, and 54.9% and 44.6% have been bullied in a lifetime and in the preceding year, respectively. The lifetime and preceding-year co-occurrence rate of FV and BV are 45% and 30.4%, respectively. Multiple logistic regressions confirm FV as a unique risk factor in predicting both direct and relational BV after controlling for a number of confounding factors. This study suggests that FV experiences should be included in the screening and assessment of risk for child BV.

Pesticide Exposure and Health Problems Among Female Horticulture Workers in Tanzania

PubMed Central

Mrema, Ezra Jonathan; Ngowi, Aiwerasia Vera; Kishinhi, Stephen Simon; Mamuya, Simon Henry

2017-01-01

Commercialization of horticulture farming, expansion of farms, and the practice of monoculture favor the proliferation of pests, which in turn increases the need for pesticides. Increased exposure to pesticides is associated with inadequate knowledge on the hazardous nature of pesticides, poor hygiene practices, lack of availability of washing facilities, and insufficient adherence to precautionary instructions on pesticide labels. Mitigating the risks posed by pesticides is considered a less compelling interest than alleviating poverty. Women working in horticulture in Tanzania usually have low levels of education and income and lack decision-making power even on matters relating to their own health. This contributes to pesticide exposure and other health challenges. Because of multiple factors, some of which act as study confounders, few studies on exposure to pesticides and health effects have been conducted among women. This review identified factors that contribute to the increased health effects among women working in the horticultural industry and how these effects relate to pesticide exposure. PMID:28690397

Pesticide Exposure and Health Problems Among Female Horticulture Workers in Tanzania.

PubMed

Mrema, Ezra Jonathan; Ngowi, Aiwerasia Vera; Kishinhi, Stephen Simon; Mamuya, Simon Henry

2017-01-01

Commercialization of horticulture farming, expansion of farms, and the practice of monoculture favor the proliferation of pests, which in turn increases the need for pesticides. Increased exposure to pesticides is associated with inadequate knowledge on the hazardous nature of pesticides, poor hygiene practices, lack of availability of washing facilities, and insufficient adherence to precautionary instructions on pesticide labels. Mitigating the risks posed by pesticides is considered a less compelling interest than alleviating poverty. Women working in horticulture in Tanzania usually have low levels of education and income and lack decision-making power even on matters relating to their own health. This contributes to pesticide exposure and other health challenges. Because of multiple factors, some of which act as study confounders, few studies on exposure to pesticides and health effects have been conducted among women. This review identified factors that contribute to the increased health effects among women working in the horticultural industry and how these effects relate to pesticide exposure.

An appraisal of statistical procedures used in derivation of reference intervals.

PubMed

Ichihara, Kiyoshi; Boyd, James C

2010-11-01

When conducting studies to derive reference intervals (RIs), various statistical procedures are commonly applied at each step, from the planning stages to final computation of RIs. Determination of the necessary sample size is an important consideration, and evaluation of at least 400 individuals in each subgroup has been recommended to establish reliable common RIs in multicenter studies. Multiple regression analysis allows identification of the most important factors contributing to variation in test results, while accounting for possible confounding relationships among these factors. Of the various approaches proposed for judging the necessity of partitioning reference values, nested analysis of variance (ANOVA) is the likely method of choice owing to its ability to handle multiple groups and being able to adjust for multiple factors. Box-Cox power transformation often has been used to transform data to a Gaussian distribution for parametric computation of RIs. However, this transformation occasionally fails. Therefore, the non-parametric method based on determination of the 2.5 and 97.5 percentiles following sorting of the data, has been recommended for general use. The performance of the Box-Cox transformation can be improved by introducing an additional parameter representing the origin of transformation. In simulations, the confidence intervals (CIs) of reference limits (RLs) calculated by the parametric method were narrower than those calculated by the non-parametric approach. However, the margin of difference was rather small owing to additional variability in parametrically-determined RLs introduced by estimation of parameters for the Box-Cox transformation. The parametric calculation method may have an advantage over the non-parametric method in allowing identification and exclusion of extreme values during RI computation.

Supervisor Autonomy and Considerate Leadership Style are Associated with Supervisors’ Likelihood to Accommodate Back Injured Workers

PubMed Central

McGuire, Connor; Kristman, Vicki L; Williams-Whitt, Kelly; Reguly, Paula; Shaw, William; Soklaridis, Sophie

2015-01-01

PURPOSE To determine the association between supervisors’ leadership style and autonomy and supervisors’ likelihood of supporting job accommodations for back-injured workers. METHODS A cross-sectional study of supervisors from Canadian and US employers was conducted using a web-based, self-report questionnaire that included a case vignette of a back-injured worker. Autonomy and two dimensions of leadership style (considerate and initiating structure) were included as exposures. The outcome, supervisors’ likeliness to support job accommodation, was measured with the Job Accommodation Scale. We conducted univariate analyses of all variables and bivariate analyses of the JAS score with each exposure and potential confounding factor. We used multivariable generalized linear models to control for confounding factors. RESULTS A total of 796 supervisors participated. Considerate leadership style (β= .012; 95% CI: .009–.016) and autonomy (β= .066; 95% CI: .025–.11) were positively associated with supervisors’ likelihood to accommodate after adjusting for appropriate confounding factors. An initiating structure leadership style was not significantly associated with supervisors’ likelihood to accommodate (β = .0018; 95% CI: −.0026–.0061) after adjusting for appropriate confounders. CONCLUSIONS Autonomy and a considerate leadership style were positively associated with supervisors’ likelihood to accommodate a back-injured worker. Providing supervisors with more autonomy over decisions of accommodation and developing their considerate leadership style may aid in increasing work accommodation for back-injured workers and preventing prolonged work disability. PMID:25595332

Selection bias and patterns of confounding in cohort studies: the case of the NINFEA web-based birth cohort.

PubMed

Pizzi, Costanza; De Stavola, Bianca L; Pearce, Neil; Lazzarato, Fulvio; Ghiotti, Paola; Merletti, Franco; Richiardi, Lorenzo

2012-11-01

Several studies have examined the effects of sample selection on the exposure-outcome association estimates in cohort studies, but the reasons why this selection may induce bias have not been fully explored. To investigate how sample selection of the web-based NINFEA birth cohort may change the confounding patterns present in the source population. The characteristics of the NINFEA participants (n=1105) were compared with those of the wider source population-the Piedmont Birth Registry (PBR)-(n=36 092), and the association of two exposures (parity and educational level) with two outcomes (low birth weight and birth by caesarean section), while controlling for other risk factors, was studied. Specifically the associations among measured risk factors within each dataset were examined and the exposure-outcome estimates compared in terms of relative ORs. The associations of educational level with the other risk factors (alcohol consumption, folic acid intake, maternal age, pregnancy weight gain, previous miscarriages) partly differed between PBR and NINFEA. This was not observed for parity. Overall, the exposure-outcome estimates derived from NINFEA only differed moderately from those obtained in PBR, with relative ORs ranging between 0.74 and 1.03. Sample selection in cohort studies may alter the confounding patterns originally present in the general population. However, this does not necessarily introduce selection bias in the exposure-outcome estimates, as sample selection may reduce some of the residual confounding present in the general population.

Improving detection of copy-number variation by simultaneous bias correction and read-depth segmentation.

PubMed

Szatkiewicz, Jin P; Wang, WeiBo; Sullivan, Patrick F; Wang, Wei; Sun, Wei

2013-02-01

Structural variation is an important class of genetic variation in mammals. High-throughput sequencing (HTS) technologies promise to revolutionize copy-number variation (CNV) detection but present substantial analytic challenges. Converging evidence suggests that multiple types of CNV-informative data (e.g. read-depth, read-pair, split-read) need be considered, and that sophisticated methods are needed for more accurate CNV detection. We observed that various sources of experimental biases in HTS confound read-depth estimation, and note that bias correction has not been adequately addressed by existing methods. We present a novel read-depth-based method, GENSENG, which uses a hidden Markov model and negative binomial regression framework to identify regions of discrete copy-number changes while simultaneously accounting for the effects of multiple confounders. Based on extensive calibration using multiple HTS data sets, we conclude that our method outperforms existing read-depth-based CNV detection algorithms. The concept of simultaneous bias correction and CNV detection can serve as a basis for combining read-depth with other types of information such as read-pair or split-read in a single analysis. A user-friendly and computationally efficient implementation of our method is freely available.

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.

Long-term exposure to particulate matter, NO2 and the oxidative potential of particulates and diabetes prevalence in a large national health survey.

PubMed

Strak, Maciej; Janssen, Nicole; Beelen, Rob; Schmitz, Oliver; Vaartjes, Ilonca; Karssenberg, Derek; van den Brink, Carolien; Bots, Michiel L; Dijst, Martin; Brunekreef, Bert; Hoek, Gerard

2017-11-01

The evidence from observational epidemiological studies of a link between long-term air pollution exposure and diabetes prevalence and incidence is currently mixed. Some studies found the strongest associations of diabetes with fine particles, other studies with nitrogen dioxide and some studies found no associations. Our aim was to investigate associations between long-term exposure to multiple air pollutants and diabetes prevalence in a large national survey in the Netherlands. We performed a cross-sectional analysis using the 2012 Dutch national health survey to investigate the associations between the 2009 annual average concentrations of multiple air pollutants (PM 10 , PM 2.5 , PM 10-2.5 , PM 2.5 absorbance, OP DTT , OP ESR and NO 2 ) and diabetes prevalence, among 289,703 adults. Air pollution exposure was assessed by land use regression models. Diabetes was defined based on a combined measure of self-reported physician diagnosis and medication prescription from an external database. Using logistic regression, we adjusted for potential confounders, including neighborhood- and individual socio-economic status and lifestyle-related risk factors such as smoking habits, alcohol consumption, physical activity and BMI. After adjustment for potential confounders, all pollutants (except PM 2.5 ) were associated with diabetes prevalence. In two-pollutant models, NO 2 and OP DTT remained associated with increased diabetes prevalence. For NO 2 and OP DTT , single-pollutant ORs per interquartile range were 1.07 (95% CI: 1.05, 1.09) and 1.08 (95% CI: 1.05, 1.10), respectively. Stratified analysis showed no consistent effect modification by any of the included known diabetes risk factors. Long-term residential air pollution exposure was associated with diabetes prevalence in a large health survey in the Netherlands, strengthening the evidence of air pollution being an important diabetes risk factor. Most consistent associations were observed for NO 2 and oxidative potential of PM 2.5 measured by the DTT assay. The finding of an association with the oxidative potential of fine particles but not with PM 2.5 , suggests that particle composition may be important for a potential effect on diabetes. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

[Reliability and validity of the Occupational Stress Scale for Chinese offshore oil platform workers].

PubMed

Chen, Wei-qing; Huang, Zi-hui; Yu, De-xin; Lin, Yan-zu; Ling, Zhi-ming; Tang, Ji-song

2003-02-01

To evaluate the validity and reliability of the Occupational Stress Scale (OSS) for Chinese offshore oil platform workers. A 51-item self-administered questionnaire developed in the light of Cooper's questionnaire and company's special situation was used to investigate 561 subjects. 51 occupational stress items relating to offshore oil production were subjected to factor analysis, and nine latent factors were identified, which explained 62.5% of the total variance. According to the contents described by the items included in each factor, they were respectively defined as: "the interface between job and family/social life (factor 1)", "career and achievement (factor 2)", "safety (factor 3)", "management problem and relationship with others at work (factor 4)", "physical factors of workplace (factor 5)", "platform living environment (factor 6)", "role in management (factor 7)", "ergonomics (factor 8)" and "organization structure (factor 9)". Significant difference in the score of five factors was observed among 12 different job categories by analysis of variance. After adjusting for potential confounding factors (age, educational level), hierarchical multiple regression analysis indicated that the score of the OSS was significantly and positively correlated with the poor mental health of the workers (P < 0.01). The consistent test between OSS and each factor showed that Cronbach's alpha were 0.72 - 0.91. The OSS is a valid and reliable tool for measuring occupational stress, and can be used to explore occupational stress and its influence on health and safety problems in offshore oil workers.

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

Influence of GSTM1 and GSTT1 genotypes and confounding factors on the frequency of sister chromatid exchange and micronucleus among road construction workers.

PubMed

Kumar, Anil; Yadav, Anita; Giri, Shiv Kumar; Dev, Kapil; Gautam, Sanjeev Kumar; Gupta, Ranjan; Aggarwal, Neeraj

2011-07-01

In the present study, we have investigated the influence of polymorphism of GSTM1 and GSTT1 genes and confounding factors such as age, sex, exposure duration and consumption habits on cytogenetic biomarkers. Frequency of sister chromatid exchanges (SCEs), high frequency cell (HFC) and cytokinesis blocked micronuclei (CBMN) were evaluated in peripheral blood lymphocytes of 115 occupationally exposed road construction workers and 105 unexposed individuals. The distribution of null and positive genotypes of glutathione-S transferase gene was evaluated by multiplex PCR among control and exposed subjects. An increased frequency of CBMN (7.03±2.08); SCE (6.95±1.76) and HFC (6.28±1.69) were found in exposed subjects when compared to referent (CBMN - 3.35±1.10; SCE - 4.13±1.30 and HFC - 3.98±1.56). These results were found statistically significant at p<0.05. When the effect of confounding factors on the frequency of studied biomarkers was evaluated, a strong positive interaction was found. The individuals having GSTM1 and GSTT1 null genotypes had higher frequency of CBMN, SCE and HFC. The association between GSTM1 and GSTT1 genotypes and studied biomarkers was found statistically significant at p<0.05. Our findings suggest that individuals having null type of GST are more susceptible to cytogenetic damage by occupational exposure regardless of confounding factors. There is a significant effect of polymorphism of these genes on cytogenetic biomarkers which are considered as early effects of genotoxic carcinogens. Copyright © 2011 Elsevier Ltd. All rights reserved.

A case matched study examining the reliability of using ImPACT to assess effects of multiple concussions.

PubMed

Barker, Trevor; Russo, Stephen A; Barker, Gaytri; Rice, Mark A; Jeffrey, Mary G; Broderick, Gordon; Craddock, Travis J A

2017-04-28

Approximately 3.8 million sport and recreational concussions occur per year, creating a need for accurate diagnosis and management of concussions. Researchers and clinicians are exploring the potential dose-response cumulative effects of concussive injuries using computerized neuropsychological exams, however, results have been mixed and/or contradictory. This study starts with a large adolescent population and applies strict inclusion criteria to examine how previous mild traumatic brain injuries affect symptom reports and neurocognitive performance on the Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) computerized tool. After applying exclusion criteria and case matching, 204 male and 99 female participants remained. These participants were grouped according to sex and the number of previous self-reported concussions and examined for overall differences on symptoms reported and scores obtained on the ImPACT neurocognitive battery composites. In an effort to further reduce confounding factors due to the varying group sizes, participants were then case matched on age, sex, and body mass index and analyzed for differences on symptoms reported and scores obtained on the ImPACT neurocognitive battery composites. Case matched analysis demonstrated males with concussions experience significantly higher rates of dizziness (p = .027, η 2  = .035), fogginess (p = .038, η 2  = .032), memory problems (p = .003, η 2  = .055), and concentration problems (p = .009, η 2  = .046) than males with no reported previous concussions. No significant effects were found for females, although females reporting two concussions demonstrated a slight trend for experiencing higher numbers of symptoms than females reporting no previous concussions. The results suggest that male adolescent athletes reporting multiple concussions have lingering concussive symptoms well after the last concussive event; however, these symptoms were found to be conflicting and better explained by complainer versus complacent attitudes in the population examined. Our results conflict with a significant portion of the current literature that uses relatively lenient inclusion and exclusion criteria, providing evidence of the importance of strict inclusion and exclusion criteria and examination of confounding factors when assessing the effects of concussions.

Mercury and neuromotor function among children in a rural town in Chile

PubMed Central

Huber, Stella Maria; Schomaker, Michael; Heumann, Christian; Schierl, Rudolf; Michalke, Bernhard; Jenni, Oskar G.; Caflisch, Jon; Muñoz, Daniel Moraga; von Ehrenstein, Ondine S.; Radon, Katja

2016-01-01

Background Mercury (Hg) exposure from artisanal gold mining has adverse effects on the neuromotor function in adults. However, few studies have examined this relationship in children. Objectives To investigate the impact of Hg exposure on children’s neuromotor function. Methods Cross-sectional data on Hg risk factors and demographics were collected from n = 288 children (response = 68.9%). Based on complete cases (CCs) (n = 130) and multiple imputations (n = 288), associations between fingernail Hg and four different neuromotor function components were calculated using multiple logistic regression adjusted for confounders. Results Of the children, 11.1, 14.9, 63.9, and 10.4% had pathologic pure motor skills, adaptive fine motor skills, adaptive gross motor skills, and static balance, respectively. No significant association between fingernail Hg and any neuromotor component was found. However, Hg burning in the household was significantly associated with children’s pathologic pure motor skills (OR 3.07 95% CI 1.03–9.18). Conclusion Elemental Hg exposure in the household might have adverse long-term effects on children’s pure motor skills. PMID:27078174

A cross-sectional study for estimation of associations between education level and osteoporosis in a Chinese men sample.

PubMed

Yu, Cai-Xia; Zhang, Xiu-Zhen; Zhang, Keqin; Tang, Zihui

2015-12-09

The main aim of this study was to evaluate the association between education level and osteoporosis (OP) in general Chinese Men. We conducted a large-scale, community-based, cross-sectional study to investigate the association by using self-report questionnaire to assess education levels. The data of 1092 men were available for analysis in this study. Multiple regression models controlling for confounding factors to include education level were performed to explore the relationship between education level and OP. Positive correlations between education level and T-score of quantitative bone ultrasound (QUS-T score) were reported (β = 0.108, P value < 0.001). Multiple regression analysis indicated that the education level was independently and significantly associated with OP (P < 0.1 for all models). The men with lower education level had a higher prevalence of OP. The education level was independently and significantly associated with OP. The prevalence of OP was more frequent in Chinese men with lower education level. ClinicalTrials.gov Identifier: NCT02451397 ; date of registration: 05/28/2015).

Factors Predicting a Good Symptomatic Outcome After Prostate Artery Embolisation (PAE).

PubMed

Maclean, D; Harris, M; Drake, T; Maher, B; Modi, S; Dyer, J; Somani, B; Hacking, N; Bryant, T

2018-02-26

As prostate artery embolisation (PAE) becomes an established treatment for benign prostatic obstruction, factors predicting good symptomatic outcome remain unclear. Pre-embolisation prostate size as a predictor is controversial with a handful of papers coming to conflicting conclusions. We aimed to investigate if an association existed in our patient cohort between prostate size and clinical benefit, in addition to evaluating percentage volume reduction as a predictor of symptomatic outcome following PAE. Prospective follow-up of 86 PAE patients at a single institution between June 2012 and January 2016 was conducted (mean age 64.9 years, range 54-80 years). Multiple linear regression analysis was performed to assess strength of association between clinical improvement (change in IPSS) and other variables, of any statistical correlation, through Pearson's bivariate analysis. No major procedural complications were identified and clinical success was achieved in 72.1% (n = 62) at 12 months. Initial prostate size and percentage reduction were found to have a significant association with clinical improvement. Multiple linear regression analysis (r 2  = 0.48) demonstrated that percentage volume reduction at 3 months (r = 0.68, p < 0.001) had the strongest correlation with good symptomatic improvement at 12 months after adjusting for confounding factors. Both the initial prostate size and percentage volume reduction at 3 months predict good symptomatic outcome at 12 months. These findings therefore aid patient selection and counselling to achieve optimal outcomes for men undergoing prostate artery embolisation.

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.

Peer influence as a potential magnifier of ADHD diagnosis.

PubMed

Aronson, Brian

2016-11-01

The prevalence of Attention Deficit and Hyperactivity Disorder (ADHD) is growing in America, but its cause is unclear. Scholars have identified many environmental factors that can cause or confound ADHD diagnosis, but epidemiological studies that try to control for confounding factors still find evidence that rates of ADHD diagnosis are increasing. As a preliminary explanation to ADHD's increasing prevalence, this article examines whether core ADHD diagnostic traits are subject to peer influence. If ADHD diagnosis can be confounded by peer influence, there are several mechanisms that could have caused increased rates of diagnosis. With data drawn from two schools across three waves in the National Longitudinal Survey of Adolescent Health (n = 2193), the author uses a stochastic actor oriented model to estimate the effect of peer influence on inattention, controlling for alternative network and behavioral causes. Results indicate that respondents have a strong likelihood to modify their self-reports of inattention, a core ADHD trait, to resemble that of their friends. Copyright © 2016 Elsevier Ltd. All rights reserved.

Desire thinking as a confounder in the relationship between mindfulness and craving: Evidence from a cross-cultural validation of the Desire Thinking Questionnaire.

PubMed

Chakroun-Baggioni, Nadia; Corman, Maya; Spada, Marcantonio M; Caselli, Gabriele; Gierski, Fabien

2017-10-01

Desire thinking and mindfulness have been associated with craving. The aim of the present study was to validate the French version of the Desire Thinking Questionnaire (DTQ) and to investigate the relationship between mindfulness, desire thinking and craving among a sample of university students. Four hundred and ninety six university students completed the DTQ and measures of mindfulness, craving and alcohol use. Results from confirmatory factor analyses showed that the two-factor structure proposed in the original DTQ exhibited suitable goodness-of-fit statistics. The DTQ also demonstrated good internal reliability, temporal stability and predictive validity. A set of linear regressions revealed that desire thinking had a confounding effect in the relationship between mindfulness and craving. The confounding role of desire thinking in the relationship between mindfulness and craving suggests that interrupting desire thinking may be a viable clinical option aimed at reducing craving. Copyright © 2017 Elsevier B.V. All rights reserved.

War-related trauma exposure and multiple risk behaviors among school-going adolescents in Northern Uganda: the mediating role of depression symptoms.

PubMed

Okello, James; Nakimuli-Mpungu, Etheldreda; Musisi, Seggane; Broekaert, Eric; Derluyn, Ilse

2013-11-01

The relationship between war-related trauma exposure, depressive symptoms and multiple risk behaviors among adolescents is less clear in sub-Saharan Africa. We analyzed data collected from a sample of school-going adolescents four years postwar. Participants completed interviews assessing various risk behaviors defined by the Youth Self Report (YSR) and a sexual risk behavior survey, and were screened for post-traumatic stress, anxiety and depression symptoms based on the Impact of Events Scale Revised (IESR) and Hopkins Symptom Checklist for Adolescents (HSCL-37A) respectively. Multivariate logistic regression was used to assess factors independently associated with multiple risk behaviors. The logistic regression model of Baron and Kenny (1986) was used to evaluate the mediating role of depression in the relationship between stressful war events and multiple risk behaviors. Of 551 participants, 139 (25%) reported multiple (three or more) risk behaviors in the past year. In the multivariate analyses, depression symptoms remained uniquely associated with multiple risk behavior after adjusting for potential confounders including socio-demographic characteristics, war-related trauma exposure variables, anxiety and post-traumatic stress symptoms. In mediation analysis, depression symptoms mediated the associations between stressful war events and multiple risk behaviors. The psychometric properties of the questionnaires used in this study are not well established in war affected African samples thus ethno cultural variation may decrease the validity of our measures. Adolescents with depression may be at a greater risk of increased engagement in multiple risk behaviors. Culturally sensitive and integrated interventions to treat and prevent depression among adolescents in post-conflict settings are urgently needed. © 2013 Elsevier B.V. All rights reserved.

Reported gum disease as a cardiovascular risk factor in adults with intellectual disabilities.

PubMed

Hsieh, K; Murthy, S; Heller, T; Rimmer, J H; Yen, G

2018-03-01

Several risk factors for cardiovascular disease (CVD) have been identified among adults with intellectual disabilities (ID). Periodontitis has been reported to increase the risk of developing a CVD in the general population. Given that individuals with ID have been reported to have a higher prevalence of poor oral health than the general population, the purpose of this study was to determine whether adults with ID with informant reported gum disease present greater reported CVD than those who do not have reported gum disease and whether gum disease can be considered a risk factor for CVD. Using baseline data from the Longitudinal Health and Intellectual Disability Study from which informant survey data were collected, 128 participants with reported gum disease and 1252 subjects without reported gum disease were identified. A series of univariate logistic regressions was conducted to identify potential confounding factors for a multiple logistic regression. The series of univariate logistic regressions identified age, Down syndrome, hypercholesterolemia, hypertension, reported gum disease, daily consumption of fruits and vegetables and the addition of table salt as significant risk factors for reported CVD. When the significant factors from the univariate logistic regression were included in the multiple logistic analysis, reported gum disease remained as an independent risk factor for reported CVD after adjusting for the remaining risk factors. Compared with the adults with ID without reported gum disease, adults in the gum disease group demonstrated a significantly higher prevalence of reported CVD (19.5% vs. 9.7%; P = .001). After controlling for other risk factors, reported gum disease among adults with ID may be associated with a higher risk of CVD. However, further research that also includes clinical indices of periodontal disease and CVD for this population is needed to determine if there is a causal relationship between gum disease and CVD. © 2017 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Prevalence of bacterial vaginosis among pregnant women attending antenatal care in Tikur Anbessa University Hospital, Addis Ababa, Ethiopia.

PubMed

Mengistie, Zemenu; Woldeamanuel, Yimtubezinash; Asrat, Daniel; Adera, Addis

2014-11-20

Bacterial vaginosis is one of the most common genital tract infections among reproductive age group. The prevalence of bacterial vaginosis varies from country to country even in the same country it varies among populations of interest. Different social and sexual factors can contribute to the development of bacterial vaginosis. The aim of this study was to determine the prevalence of bacterial vaginosis and to identify the possible risk factors associated among pregnant women attending antenatal care in Tikur Anbessa University Hospital, Addis Ababa, Ethiopia. Randomly selected 57 symptomatic and 195 asymptomatic pregnant women aged between 18 and 40 years visiting obstetric and gynecological clinic from November 2011 to April 2012 screenedusing Gram stain Nugent scoring system. Statistical analysis like univariate analysis to calculate frequencies and proportions, bivariate analysis to see association of selected exposure variables with the outcome variable, and multivariate analysis to check the association of possible factors with bacterial vaginosis by adjusting potential confounding factors was calculated using SPSS (Version 16.0). The prevalence of bacterial vaginosis is 19.4% using Gram stain Nugent scoring system. In addition, prevalence of bacterial vaginosis is 31.6% and 15.9% among symptomatic and asymptomatic pregnant women respectively. A high percentage of bacterial vaginosis positive pregnant women were asymptomatic (63.3%). 36.7% bacterial vaginosis positive pregnant women reported abnormal vaginal discharge with or without unpleasant smell. Multiple lifetime sexual partner (OR: 8.6; 95% CI: 2.5, 29) and previous history of spontaneous abortion (OR: 5.9; 95% CI: 1.5, 23) had remained significantly associated with prevalence of bacterial vaginosis. The prevalence of bacterial vaginosis is higher among asymptomatic pregnant women and associated with the factors previous history of multiple lifetime sexual partner and spontaneous abortion.

SELECTING LEAST-DISTURBED SURVEY SITES FOR GREAT PLAINS STREAMS AND RIVERS

EPA Science Inventory

True reference condition probably does not exist for streams in highly utilized regions such as the Great Plains. Selecting least-disturbed sites for large regions is confounded by the association between human uses and natural gradients, and by multiple kinds of disturbance. U...

Use of a quality trait index to increase the reliability of phenotypic evaluations in broccoli

USDA-ARS?s Scientific Manuscript database

Selection of superior broccoli hybrids involves multiple considerations, including optimization of head quality traits. Quality assessment of broccoli heads is often confounded by relatively subjective human preferences for optimal appearance of heads. To assist the selection process, we assessed fi...

Smartberries: Interpreting Erdrich's Love Medicine

ERIC Educational Resources Information Center

Treuer, David

2005-01-01

The structure of "Love Medicines" interpreted by Hertha D. Sweet Wong who claims that the book's "multiple narrators confound conventional Western expectations of an autonomous protagonist, a dominant narrative voice, and a consistently chronological narrative". "Love Medicine" is a brilliant use of the Western literary tactics that create the…

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.

A method for sensitivity analysis to assess the effects of measurement error in multiple exposure variables using external validation data.

PubMed

Agogo, George O; van der Voet, Hilko; van 't Veer, Pieter; Ferrari, Pietro; Muller, David C; Sánchez-Cantalejo, Emilio; Bamia, Christina; Braaten, Tonje; Knüppel, Sven; Johansson, Ingegerd; van Eeuwijk, Fred A; Boshuizen, Hendriek C

2016-10-13

Measurement error in self-reported dietary intakes is known to bias the association between dietary intake and a health outcome of interest such as risk of a disease. The association can be distorted further by mismeasured confounders, leading to invalid results and conclusions. It is, however, difficult to adjust for the bias in the association when there is no internal validation data. We proposed a method to adjust for the bias in the diet-disease association (hereafter, association), due to measurement error in dietary intake and a mismeasured confounder, when there is no internal validation data. The method combines prior information on the validity of the self-report instrument with the observed data to adjust for the bias in the association. We compared the proposed method with the method that ignores the confounder effect, and with the method that ignores measurement errors completely. We assessed the sensitivity of the estimates to various magnitudes of measurement error, error correlations and uncertainty in the literature-reported validation data. We applied the methods to fruits and vegetables (FV) intakes, cigarette smoking (confounder) and all-cause mortality data from the European Prospective Investigation into Cancer and Nutrition study. Using the proposed method resulted in about four times increase in the strength of association between FV intake and mortality. For weakly correlated errors, measurement error in the confounder minimally affected the hazard ratio estimate for FV intake. The effect was more pronounced for strong error correlations. The proposed method permits sensitivity analysis on measurement error structures and accounts for uncertainties in the reported validity coefficients. The method is useful in assessing the direction and quantifying the magnitude of bias in the association due to measurement errors in the confounders.

Offspring ADHD as a risk factor for parental marital problems: controls for genetic and environmental confounds.

PubMed

Schermerhorn, Alice C; D'Onofrio, Brian M; Slutske, Wendy S; Emery, Robert E; Turkheimer, Eric; Harden, K Paige; Heath, Andrew C; Martin, Nicholas G

2012-12-01

Previous studies have found that child attention-deficit/hyperactivity disorder (ADHD) is associated with more parental marital problems. However, the reasons for this association are unclear. The association might be due to genetic or environmental confounds that contribute to both marital problems and ADHD. Data were drawn from the Australian Twin Registry, including 1,296 individual twins, their spouses, and offspring. We studied adult twins who were discordant for offspring ADHD.Using a discordant twin pairs design, we examined the extent to which genetic and environmental confounds,as well as measured parental and offspring characteristics, explain the ADHD-marital problems association. Offspring ADHD predicted parental divorce and marital conflict. The associations were also robust when comparing differentially exposed identical twins to control for unmeasured genetic and environmental factors, when controlling for measured maternal and paternal psychopathology,when restricting the sample based on timing of parental divorce and ADHD onset, and when controlling for other forms of offspring psychopathology. Each of these controls rules out alternative explanations for the association. The results of the current study converge with those of prior research in suggesting that factors directly associated with offspring ADHD increase parental marital problems.

Offspring ADHD as a Risk Factor for Parental Marital Problems: Controls for Genetic and Environmental Confounds

PubMed Central

Schermerhorn, Alice C.; D’Onofrio, Brian M.; Slutske, Wendy S.; Emery, Robert E.; Turkheimer, Eric; Harden, K. Paige; Heath, Andrew C.; Martin, Nicholas G.

2013-01-01

Background Previous studies have found that child attention-deficit/hyperactivity disorder (ADHD) is associated with more parental marital problems. The reasons for this association are unclear, however. The association might be due to genetic or environmental confounds that contribute to both marital problems and ADHD. Method Data were drawn from the Australian Twin Registry, including 1296 individual twins, their spouses, and offspring. We studied adult twins who were discordant for offspring ADHD. Using a discordant twin pairs design, we examined the extent to which genetic and environmental confounds, as well as measured parental and offspring characteristics, explain the ADHD-marital problems association. Results Offspring ADHD predicted parental divorce and marital conflict. The associations were also robust when comparing differentially exposed identical twins to control for unmeasured genetic and environmental factors, when controlling for measured maternal and paternal psychopathology, when restricting the sample based on timing of parental divorce and ADHD onset, and when controlling for other forms of offspring psychopathology. Each of these controls rules out alternative explanations for the association. Conclusion The results of the current study converge with those of prior research in suggesting that factors directly associated with offspring ADHD increase parental marital problems. PMID:22958575

Biomechanical and psychosocial exposures are independent risk factors for carpal tunnel syndrome: assessment of confounding using causal diagrams.

PubMed

Harris-Adamson, Carisa; Eisen, Ellen A; Neophytou, Andreas; Kapellusch, Jay; Garg, Arun; Hegmann, Kurt T; Thiese, Matthew S; Dale, Ann Marie; Evanoff, Bradley; Bao, Stephen; Silverstein, Barbara; Gerr, Fred; Burt, Susan; Rempel, David

2016-11-01

Between 2001 and 2010, six research groups conducted coordinated prospective studies of carpal tunnel syndrome (CTS) incidence among US workers from various industries to estimate exposure-response relationships. This analysis examined the presence and magnitude of confounding between biomechanical and workplace psychosocial factors and incidence of dominant-hand CTS. 1605 participants, without CTS at enrolment, were followed for up to 3.5 years (2471 person-years). Demographic information, medical history and workplace psychosocial stress measures were collected at baseline. Individual workplace biomechanical exposures were collected for each task and combined across the workweek using time-weighted averaging (TWA). CTS case criteria were based on symptoms and results of electrophysiological testing. HRs were estimated with Cox proportional hazard models. Confounding was assessed using causal diagrams and an empirical criterion of 10% or greater change in effect estimate magnitude. There were 109 incident CTS cases (IR=4.41/100 person-years; 6.7% cumulative incidence). The relationships between CTS and forceful repetition rate, % time forceful hand exertion and the Threshold Limit Value for Hand Activity Level (TLV-HAL) were slightly confounded by decision latitude with effect estimates being attenuated towards the null (10-14% change) after adjustment. The risk of CTS among participants reporting high job strain was attenuated towards the null by 14% after adjusting for the HAL Scale or the % time forceful hand exertions. Although attenuation of the relationships between CTS and some biomechanical and work psychosocial exposures was observed after adjusting for confounding, the magnitudes were small and confirmed biomechanical and work psychosocial exposures as independent risk factors for incident CTS. 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/.

Reproductive history and post-reproductive mortality: A sibling comparison analysis using Swedish register data.

PubMed

Barclay, Kieron; Keenan, Katherine; Grundy, Emily; Kolk, Martin; Myrskylä, Mikko

2016-04-01

A growing body of evidence suggests that reproductive history influences post-reproductive mortality. A potential explanation for this association is confounding by socioeconomic status in the family of origin, as socioeconomic status is related to both fertility behaviours and to long-term health. We examine the relationship between age at first birth, completed parity, and post-reproductive mortality and address the potential confounding role of family of origin. We use Swedish population register data for men and women born 1932-1960, and examine both all-cause and cause-specific mortality. The contributions of our study are the use of a sibling comparison design that minimizes residual confounding from shared family background characteristics and assessment of cause-specific mortality that can shed light on the mechanisms linking reproductive history to mortality. Our results were entirely consistent with previous research on this topic, with teenage first time parents having higher mortality, and the relationship between parity and mortality following a U-shaped pattern where childless men and women and those with five or more children had the highest mortality. These results indicate that selection into specific fertility behaviours based upon socioeconomic status and experiences within the family of origin does not explain the relationship between reproductive history and post-reproductive mortality. Additional analyses where we adjust for other lifecourse factors such as educational attainment, attained socioeconomic status, and post-reproductive marital history do not change the results. Our results add an important new level of robustness to the findings on reproductive history and mortality by showing that the association is robust to confounding by factors shared by siblings. However it is still uncertain whether reproductive history causally influences health, or whether other confounding factors such as childhood health or risk-taking propensity could explain the association. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Validation sampling can reduce bias in health care database studies: an illustration using influenza vaccination effectiveness.

PubMed

Nelson, Jennifer Clark; Marsh, Tracey; Lumley, Thomas; Larson, Eric B; Jackson, Lisa A; Jackson, Michael L

2013-08-01

Estimates of treatment effectiveness in epidemiologic studies using large observational health care databases may be biased owing to inaccurate or incomplete information on important confounders. Study methods that collect and incorporate more comprehensive confounder data on a validation cohort may reduce confounding bias. We applied two such methods, namely imputation and reweighting, to Group Health administrative data (full sample) supplemented by more detailed confounder data from the Adult Changes in Thought study (validation sample). We used influenza vaccination effectiveness (with an unexposed comparator group) as an example and evaluated each method's ability to reduce bias using the control time period before influenza circulation. Both methods reduced, but did not completely eliminate, the bias compared with traditional effectiveness estimates that do not use the validation sample confounders. Although these results support the use of validation sampling methods to improve the accuracy of comparative effectiveness findings from health care database studies, they also illustrate that the success of such methods depends on many factors, including the ability to measure important confounders in a representative and large enough validation sample, the comparability of the full sample and validation sample, and the accuracy with which the data can be imputed or reweighted using the additional validation sample information. Copyright © 2013 Elsevier Inc. All rights reserved.

Validation sampling can reduce bias in healthcare database studies: an illustration using influenza vaccination effectiveness

PubMed Central

Nelson, Jennifer C.; Marsh, Tracey; Lumley, Thomas; Larson, Eric B.; Jackson, Lisa A.; Jackson, Michael

2014-01-01

Objective Estimates of treatment effectiveness in epidemiologic studies using large observational health care databases may be biased due to inaccurate or incomplete information on important confounders. Study methods that collect and incorporate more comprehensive confounder data on a validation cohort may reduce confounding bias. Study Design and Setting We applied two such methods, imputation and reweighting, to Group Health administrative data (full sample) supplemented by more detailed confounder data from the Adult Changes in Thought study (validation sample). We used influenza vaccination effectiveness (with an unexposed comparator group) as an example and evaluated each method’s ability to reduce bias using the control time period prior to influenza circulation. Results Both methods reduced, but did not completely eliminate, the bias compared with traditional effectiveness estimates that do not utilize the validation sample confounders. Conclusion Although these results support the use of validation sampling methods to improve the accuracy of comparative effectiveness findings from healthcare database studies, they also illustrate that the success of such methods depends on many factors, including the ability to measure important confounders in a representative and large enough validation sample, the comparability of the full sample and validation sample, and the accuracy with which data can be imputed or reweighted using the additional validation sample information. PMID:23849144

Estimating the monetary value of willingness to pay for E-book reader's attributes using partially confounded factorial conjoint choice experiment

NASA Astrophysics Data System (ADS)

Yong, Chin-Khian

2013-09-01

A partially confounded factorial conjoint choice experiments design was used to examine the monetary value of the willingness to pay for E-book Reader's attributes. Conjoint analysis is an efficient, cost-effective, and most widely used quantitative method in marketing research to understand consumer preferences and value trade-off. Value can be interpreted by customer or consumer as the received of multiple benefits from a price that was paid. The monetary value of willingness to pay for battery life, internal memory, external memory, screen size, text to Speech, touch screen, and converting handwriting to digital text of E-book reader were estimated in this study. Due to the significant interaction effect of the attributes with the price, the monetary values for the seven attributes were found to be different at different values of odds of purchasing versus not purchasing. The significant interactions effects were one of the main contribution of the partially confounded factorial conjoint choice experiment.

Defining the Path Between Social and Economic Factors, Clinical and Lifestyle Determinants, and Cardiovascular Disease.

PubMed

Kastorini, Christina-Maria; Milionis, Haralampos J; Georgousopoulou, Ekavi; Kalantzi, Kallirroi; Nikolaou, Vassilios; Vemmos, Konstantinos N; Goudevenos, John A; Panagiotakos, Demosthenes B

2015-12-01

Low socioeconomic status is associated with poorer cardiovascular health. The aim of the present work was to evaluate how social and economic factors influence modifiable cardiovascular disease risk factors and thus, acute coronary syndrome or ischemic stroke presence. One thousand participants were enrolled; 250 consecutive patients with a first acute coronary syndrome (83% were male, 60 ± 12 years old) and 250 control subjects, as well as 250 consecutive patients with a first ischemic stroke (56% were male, 77 ± 9 years old) and 250 control subjects. The control subjects were population-based and age-sex matched with the patients. Detailed information regarding their medical records, lifestyle characteristics, education level, financial status satisfaction, and type of occupation were recorded. After controlling for potential confounding factors, significant inverse associations were observed regarding financial status satisfaction and sedentary/mental type occupation with acute coronary syndrome or stroke presence, but not with the educational level. Nevertheless, further evaluation using path analysis, revealed quite different results, indicating that the education level influenced the type of occupation and financial satisfaction, hence affecting indirectly the likelihood of developing a cardiovascular disease event. Social and economic parameters interact with modifiable cardiovascular disease risk factors through multiple pathways. Copyright © 2015 World Heart Federation (Geneva). Published by Elsevier B.V. All rights reserved.

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.

Associations between workplace factors and carpal tunnel syndrome: A multi-site cross sectional study.

PubMed

Fan, Z Joyce; Harris-Adamson, Carisa; Gerr, Fred; Eisen, Ellen A; Hegmann, Kurt T; Bao, Stephen; Silverstein, Barbara; Evanoff, Bradley; Dale, Ann Marie; Thiese, Matthew S; Garg, Arun; Kapellusch, Jay; Burt, Susan; Merlino, Linda; Rempel, David

2015-05-01

Few large epidemiologic studies have used rigorous case criteria, individual-level exposure measurements, and appropriate control for confounders to examine associations between workplace psychosocial and biomechanical factors and carpal tunnel syndrome (CTS). Pooling data from five independent research studies, we assessed associations between prevalent CTS and personal, work psychosocial, and biomechanical factors while adjusting for confounders using multivariable logistic regression. Prevalent CTS was associated with personal factors of older age, obesity, female sex, medical conditions, previous distal upper extremity disorders, workplace measures of peak forceful hand activity, a composite measure of force and repetition (ACGIH Threshold Limit Value for Hand Activity Level), and hand vibration. In this cross-sectional analysis of production and service workers, CTS prevalence was associated with workplace and biomechanical factors. The findings were similar to those from a prospective analysis of the same cohort with differences that may be due to recall bias and other factors. © 2015 Wiley Periodicals, Inc.

Evaluation in medical education: A topical review of target parameters, data collection tools and confounding factors.

PubMed

Schiekirka, Sarah; Feufel, Markus A; Herrmann-Lingen, Christoph; Raupach, Tobias

2015-01-01

Evaluation is an integral part of education in German medical schools. According to the quality standards set by the German Society for Evaluation, evaluation tools must provide an accurate and fair appraisal of teaching quality. Thus, data collection tools must be highly reliable and valid. This review summarises the current literature on evaluation of medical education with regard to the possible dimensions of teaching quality, the psychometric properties of survey instruments and potential confounding factors. We searched Pubmed, PsycINFO and PSYNDEX for literature on evaluation in medical education and included studies published up until June 30, 2011 as well as articles identified in the "grey literature". RESULTS are presented as a narrative review. We identified four dimensions of teaching quality: structure, process, teacher characteristics, and outcome. Student ratings are predominantly used to address the first three dimensions, and a number of reliable tools are available for this purpose. However, potential confounders of student ratings pose a threat to the validity of these instruments. Outcome is usually operationalised in terms of student performance on examinations, but methodological problems may limit the usability of these data for evaluation purposes. In addition, not all examinations at German medical schools meet current quality standards. The choice of tools for evaluating medical education should be guided by the dimension that is targeted by the evaluation. Likewise, evaluation results can only be interpreted within the context of the construct addressed by the data collection tool that was used as well as its specific confounding factors.

Relationship Between Circulating Thyroid-Stimulating Hormone, Free Thyroxine, and Free Triiodothyronine Concentrations and 9-Year Mortality in Euthyroid Elderly Adults.

PubMed

Ceresini, Graziano; Marina, Michela; Lauretani, Fulvio; Maggio, Marcello; Bandinelli, Stefania; Ceda, Gian P; Ferrucci, Luigi

2016-03-01

To determine the association between plasma thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) levels and all-cause mortality in older adults who had levels of all three hormones in the normal range. Longitudinal. Community-based. Euthyroid Invecchiare in Chianti study participants aged 65 and older (N = 815). Plasma TSH, FT3, and FT4 levels were predictors, and 9-year all-cause mortality was the outcome. Cox proportional hazards models adjusted for confounders were used to examine the relationship between TSH, FT3, and FT4 quartiles and all-cause mortality over 9 years of follow-up. During follow-up (mean person-years 8,643.7, range 35.4-16,985.0), 181 deaths occurred (22.2%). Participants with TSH in the lowest quartile had higher mortality than the rest of the population. After adjusting for multiple confounders, participants with TSH in the lowest quartile (hazard ratio = 2.22, 95% confidence interval = 1.19-4.22) had significantly higher all-cause mortality than those with TSH in the highest quartile. Neither FT3 nor FT4 was associated with mortality. In elderly euthyroid subjects, normal-low TSH is an independent risk factor for all-cause mortality. © 2016, Copyright the Authors Journal compilation © 2016, The American Geriatrics Society.

Serotonin-1A receptors in major depression quantified using PET: controversies, confounds, and recommendations.

PubMed

Shrestha, Saurav; Hirvonen, Jussi; Hines, Christina S; Henter, Ioline D; Svenningsson, Per; Pike, Victor W; Innis, Robert B

2012-02-15

The serotonin-1A (5-HT(1A)) receptor is of particular interest in human positron emission tomography (PET) studies of major depressive disorder (MDD). Of the eight studies investigating this issue in the brains of patients with MDD, four reported decreased 5-HT(1A) receptor density, two reported no change, and two reported increased 5-HT(1A) receptor density. While clinical heterogeneity may have contributed to these differing results, methodological factors by themselves could also explain the discrepancies. This review highlights several of these factors, including the use of the cerebellum as a reference region and the imprecision of measuring the concentration of parent radioligand in arterial plasma, the method otherwise considered to be the 'gold standard'. Other potential confounds also exist that could restrict or unexpectedly affect the interpretation of results. For example, the radioligand may be a substrate for an efflux transporter - like P-gp - at the blood-brain barrier; furthermore, the binding of the radioligand to the receptor in various stages of cellular trafficking is unknown. Efflux transport and cellular trafficking may also be differentially expressed in patients compared to healthy subjects. We believe that, taken together, the existing disparate findings do not reliably answer the question of whether 5-HT(1A) receptors are altered in MDD or in subgroups of patients with MDD. In addition, useful meta-analysis is precluded because only one of the imaging centers acquired all the data necessary to address these methodological concerns. We recommend that in the future, individual centers acquire more thorough data capable of addressing methodological concerns, and that multiple centers collaborate to meaningfully pool their data for meta-analysis. Published by Elsevier Inc.

Intrauterine growth retardation in Iowa communities with herbicide-contaminated drinking water supplies

USGS Publications Warehouse

Munger, R.; Isacson, P.; Hu, S.; Burns, T.; Hanson, J.; Lynch, C.F.; Cherryholmes, K.; Van Dorpe, P.; Hausler, W.J.

1997-01-01

In a statewide survey of 856 Iowa municipal drinking water supplies in 1986-1987 the Rathbun rural water system was found to contain elevated levels of triazine herbicides. Rates of low birth weight, prematurity, and intrauterine growth retardation (IUGR) in live singleton births during the period 1984-1990 by women living in 13 communities served by the Rathbun water system were compared to other communities of similar size in the same Iowa counties. The Rathbun communities had a greater risk of IUGR than southern Iowa communities with other surface sources of drinking water (relative risk = 1.8; 95% CI = 1.3, 2.7). Multiple linear regression analyses revealed that levels of the herbicides atrazine, metolachlor, and cyanazine were each significant predictors of community IUGR rates in southern Iowa after controlling for several potentially confounding factors including maternal smoking and socioeconomic variables. The association with IUGR was strongest for atrazine, but all three herbicides were intercorrelated and the independent contributions of each to IUGR risk could not be determined. We conclude that communities in southern Iowa with drinking water supplies contaminated with herbicides have elevated rates of IUGR compared to neighboring communities with different water supplies. Because of the limitations of the ecologic design of this study, including aggregate rather than individual measures of exposure and limited ability to control for confounding factors related to source of drinking water and risk of IUGR, a strong causal relationship between any specific water contaminant and risk of IUGR cannot yet be inferred. The association between the water supplied to the Rathbun communities and the increased risk of IUGR should be considered a preliminary finding that needs to be verified by more detailed epidemiologic studies.

Serotonin-1A receptors in major depression quantified using PET: controversies, confounds, and recommendations

PubMed Central

Shrestha, Saurav; Hirvonen, Jussi; Hines, Christina S.; Henter, Ioline; Svenningsson, Per; Pike, Victor W.; Innis, Robert B.

2011-01-01

The serotonin-1A (5-HT1A) receptor is of particular interest in human positron emission tomography (PET) studies of major depressive disorder (MDD). Of the eight studies investigating this issue in the brains of patients with MDD, four reported decreased 5-HT1A receptor density, two reported no change, and two reported increased 5-HT1A receptor density. While clinical heterogeneity may have contributed to these differing results, methodological factors by themselves could also explain the discrepancies. This review highlights several of these factors, including the use of the cerebellum as a reference region and the imprecision of measuring the concentration of parent radioligand in arterial plasma, the method otherwise considered to be the `gold standard'. Other potential confounds also exist that could restrict or unexpectedly affect the interpretation of results. For example, the radioligand may be a substrate for an efflux transporter—like P-gp—at the blood-brain barrier; furthermore, the binding of the radioligand to the receptor in various stages of cellular trafficking is unknown. Efflux transport and cellular trafficking may also be differentially expressed in patients compared to healthy subjects. We believe that, taken together, the existing disparate findings do not reliably answer the question of whether 5-HT1A receptors are altered in MDD or in subgroups of patients with MDD. In addition, useful meta-analysis is precluded because only one of the imaging centers acquired all the data necessary to address these methodological concerns. We recommend that in the future, individual centers acquire more thorough data capable of addressing methodological concerns, and that multiple centers collaborate to meaningfully pool their data for meta-analysis. PMID:22155042

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.

Small intestinal permeability is increased in diarrhoea predominant IBS, while alterations in gastroduodenal permeability in all IBS subtypes are largely attributable to confounders.

PubMed

Mujagic, Z; Ludidi, S; Keszthelyi, D; Hesselink, M A M; Kruimel, J W; Lenaerts, K; Hanssen, N M J; Conchillo, J M; Jonkers, D M A E; Masclee, A A M

2014-08-01

Intestinal permeability has been studied in small groups of IBS patients with contrasting findings. To assess intestinal permeability at different sites of the GI tract in different subtypes of well-characterised IBS patients and healthy controls (HC), and to assess potential confounding factors. IBS patients and HC underwent a multi-sugar test to assess site-specific intestinal permeability. Sucrose excretion and lactulose/rhamnose ratio in 0-5 h urine indicated gastroduodenal and small intestinal permeability, respectively. Sucralose/erythritol ratio in 0-24 h and 5-24 h urine indicated whole gut and colonic permeability, respectively. Linear regression analysis was used to assess the association between IBS groups and intestinal permeability and to adjust for age, sex, BMI, anxiety or depression, smoking, alcohol intake and use of medication. Ninety-one IBS patients, i.e. 37% IBS-D, 23% IBS-C, 33% IBS-M and 7% IBS-U and 94 HC were enrolled. Urinary sucrose excretion was significantly increased in the total IBS group [μmol, median (Q1;Q3): 5.26 (1.82;11.03) vs. 2.44 (0.91;5.85), P < 0.05], as well as in IBS-C and IBS-D vs. HC. However, differences attenuated when adjusting for confounders. The lactulose/rhamnose ratio was increased in IBS-D vs. HC [0.023 (0.013;0.038) vs. 0.014 (0.008;0.025), P < 0.05], which remained significant after adjustment for confounders. No difference was found in 0-24 and 5-24 h sucralose/erythritol ratio between groups. Small intestinal permeability is increased in patients with IBS-D compared to healthy controls, irrespective of confounding factors. Adjustment for confounders is necessary when studying intestinal permeability, especially in a heterogeneous disorder such as IBS. © 2014 John Wiley & Sons Ltd.

Does vagotomy protect against multiple sclerosis?

PubMed

Sundbøll, Jens; Horváth-Puhó, Erzsébet; Adelborg, Kasper; Svensson, Elisabeth

2017-07-01

To examine the association between vagotomy and multiple sclerosis. We conducted a matched cohort study of all patients who underwent truncal or super-selective vagotomy and a comparison cohort, by linking Danish population-based medical registries (1977-1995). Hazard ratios (HRs) for multiple sclerosis, adjusting for potential confounders were computed by means of Cox regression analysis. Median age of multiple sclerosis onset corresponded to late onset multiple sclerosis. No association with multiple sclerosis was observed for truncal vagotomy (0-37 year adjusted HR=0.91, 95% confidence interval [CI]: 0.48-1.74) or super-selective vagotomy (0-37 year adjusted HR=1.28, 95% CI: 0.79-2.09) compared with the general population. We found no association between vagotomy and later risk of late onset multiple sclerosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Prevalence of cholera risk factors between migrant Haitians and Dominicans in the Dominican Republic.

PubMed

Lund, Andrea J; Keys, Hunter M; Leventhal, Stephanie; Foster, Jennifer W; Freeman, Matthew C

2015-03-01

To determine whether cholera risk factor prevalence in the Dominican Republic can be explained by nationality, independent of other factors, given the vulnerability of many Haitians in the country and the need for targeted prevention. A cross-sectional, observational household survey (103 Haitian and 260 Dominican) was completed in 18 communities in July 2012. The survey included modules for demographics, knowledge, socioeconomic status, and access to adequate water, sanitation, and hygiene (WASH) infrastructure. Logistic regression assessed differential access to WASH infrastructure and Poisson regression assessed differences in cholera knowledge, controlling for potential confounders. Dominican and Haitian households differed on demographic characteristics. Haitians had lower educational attainment, socioeconomic status, and less knowledge of cholera than Dominicans (adjusted odds ratio [aOR] = 0.66; 95% confidence interval [95%CI] = 0.55-0.81). Access to improved drinking water was low for both groups, but particularly low among rural Haitians (aOR = 0.21; 95%CI: 0.04-1.01). No differences were found in access to sanitation after adjusting for sociodemographic confounders (aOR = 1.00; 95%CI: 0.57-1.76). Urban/rural geography and socioeconomic status play a larger role in cholera risk factor prevalence than nationality, indicating that Haitians' perceived vulnerability to cholera is confounded by contextual factors. Understanding the social dynamics that lead to cholera risk can inform control strategies, leading to better targeting and the possibility of eliminating cholera from the island.

White matter disease severity of the brain and its association with geriatric syndromes.

PubMed

Alagiakrishnan, Kannayiram; Hsueh, Jenny; Zhang, Edwin; Khan, Khurshid; Senthilselvan, Ambikaipakan

2013-11-01

White matter disease (WMD) of the brain is considered to be secondary to small vessel ischemia and can be a single unifying risk factor for the development of geriatric syndromes. The aim of our study was to investigate the association of the global and regional severity of WMD in the brain with geriatric syndromes burden. In our retrospective study, consecutive outpatient charts from patients seen between January 2010 and June 2011 at University of Alberta Hospital Seniors Clinic were reviewed. Subjects with brain computed tomography (CT) scans were included in the study. Subjects with incomplete information or with diseases that confounded WMD assessment on CT were excluded. White matter disease was quantified on CT using Wahlund scoring. A multiple linear regression analysis was conducted to determine the association of WMD severity with geriatric syndromes burden after controlling for confounding vascular risk factors. Of the 505 subjects, 326 (64.6%) were women. Mean age of the study patients was 79.8 years (SD ± 7.04), prevalence of WMD disease was 79.4%, and mean WMD score was 5.1 (SD ± 4.4). In subjects aged < and > 80 years, the mean number of geriatric syndromes was 2.83 (standard error of the mean [SE] 0.08) and 3.22 (SE 0.08), respectively. In the adjusted regression analysis, there was a significant association between WMD severity, globally (regression coefficient (β) = 0.457, SE 0.155; P = 0.003), as well as WMD in specific regions: frontal (P < 0.001), parieto-occipital (P = 0.004), and infratentorial regions (P = 0.04) with geriatric syndromes burden. The association remains even after correcting for age, sex, and all vascular risk factors. In our study, there was a significant association between the severity of global and selected regional WMD of the brain with geriatric syndromes burden, thus raising the possibility of a shared biologic association through vascular pathology of the brain.

Sexual satisfaction in females with premenstrual symptoms.

PubMed

Nowosielski, Krzysztof; Drosdzol, Agnieszka; Skrzypulec, Violetta; Plinta, Ryszard

2010-11-01

The impact of premenstrual symptoms, such as the premenstrual syndrome (PMS) and the premenstrual dysphoric disorder (PMDD), on sexual satisfaction, sexual distress, and sexual behaviors has not yet been established. To assess the correlates and risk factors of sexual satisfaction and to evaluate sexual behaviors among Polish women with premenstrual symptoms. 2,500 females, aged 18 to 45 years, from the Upper Silesian region of Poland were eligible for the questionnaire-based, prospective population study. All the inclusion criteria were met by 1,540 women who constituted the final study group. The participants were further divided into two subgroups: PMS+ (749 females) and PMS- (791 healthy subjects). Two additional subgroups were created: PMDD+ encompassing 32 subjects diagnosed with PMDD, and PMDD- comprising 32 healthy women, matched to the PMDD+ females for age, marital status, education level, employment status, place of living, and body mass index. A multiple logistic regression analysis was performed to evaluate the influence of PMS on sexual satisfaction and adjust for potential confounders. To evaluate risk factors for sexual dissatisfaction in a population of Polish females of reproductive age, diagnosed with PMS and PMDD. Women from the PMS+ group were less sexually satisfied than PMS- (77.73% vs. 88.66%, P=0.001) and reported more sexual distress (28.65% vs. 15.24%, P=0.001). There were no significant differences in sexual satisfaction between PMDD- and PMDD+. Sexual satisfaction correlated positively with a higher frequency of sexual intercourses and a higher level of education. The presence of PMS correlated negatively with sexual satisfaction, even after adjusting for potential confounders in the multivariate logistic regression model (odds ratio=0.48; confidence interval: 0.26-0.89; P=0.02). The presence of PMS is a risk factor for sexual dissatisfaction in Polish women of reproductive age. © 2010 International Society for Sexual Medicine.

Comparative risk of microalbuminuria and proteinuria in UK residents of south Asian and white European ethnic background with type 2 diabetes: a report from UKADS.

PubMed

Raymond, Neil T; Paul O'Hare, J; Bellary, Srikanth; Kumar, Sudhesh; Jones, Alan; Barnett, Anthony H

2011-11-01

This study investigated and compared the prevalence of microalbuminuria and overt proteinuria and their determinants in a cohort of UK resident patients of white European or south Asian ethnicity with type 2 diabetes mellitus. A total of 1978 patients, comprising 1486 of south Asian and 492 of white European ethnicity, in 25 general practices in Coventry and Birmingham inner city areas in England were studied in a cross-sectional study. Demographic and risk factor data were collected and presence of microalbuminuria and overt proteinuria assessed. ISRCTN 38297969. Prevalences of microalbuminuria and overt proteinuria. Urinary albumin:creatinine measurements were available for 1852 (94%) patients. The south Asian group had a lower prevalence of microalbuminuria, 19% vs. 23% and a higher prevalence of overt proteinuria, 8% vs. 3%, χ(2) = 15.85, 2df, P = 0.0004. In multiple logistic regression models, adjusted for confounding factors, significantly increased risk for the south Asian vs. white European patients for overt proteinuria was shown; OR (95% CI) 2.17 (1.05, 4.49), P = 0.0365. For microalbuminuria, an interaction effect for ethnicity and duration of diabetes suggested that risk for south Asian patients was lower in early years following diagnosis; OR for SA vs. WH at durations 0 and 1 year were 0.56 (0.37, 0.86) and 0.59 (0.39, 0.89) respectively. After 20 years' duration, OR = 1.40 (0.63, 3.08). Comparability of ethnicity defined groups; statistical methods controlled for differences between groups, but residual confounding may remain. Analyses are based on a single measure of albumin:creatinine ratio. There were significant differences between ethnicity groups in risk factor profiles and microalbuminuria and overt proteinuria outcomes. Whilst south Asian patients had no excess risk of microalbuminuria, the risk of overt proteinuria was elevated significantly, which might be explained by faster progression of renal dysfunction in patients of south Asian ethnicity.

Investigation of genetic variation in scavenger receptor class B, member 1 (SCARB1) and association with serum carotenoids

PubMed Central

McKay, Gareth J; Loane, Edward; Nolan, John M; Patterson, Christopher C; Meyers, Kristin J; Mares, Julie A; Yonova-Doing, Ekaterina; Hammond, Christopher J; Beatty, Stephen; Silvestri, Giuliana

2013-01-01

Objective To investigate association of scavenger receptor class B, member 1 (SCARB1) genetic variants with serum carotenoid levels of lutein (L) and zeaxanthin (Z) and macular pigment optical density (MPOD). Design A cross-sectional study of healthy adults aged 20-70. Participants 302 participants recruited following local advertisement. Methods MPOD was measured by customized heterochromatic flicker photometry. Fasting blood samples were taken for serum L and Z measurement by HPLC and lipoprotein analysis by spectrophotometric assay. Forty-seven single nucleotide polymorphisms (SNPs) across SCARB1 were genotyped using Sequenom technology. Association analyses were performed using PLINK to compare allele and haplotype means, with adjustment for potential confounding and correction for multiple comparisons by permutation testing. Replication analysis was performed in the TwinsUK and CAREDS cohorts. Main outcome measures Odds ratios (ORs) for macular pigment optical density area, serum lutein and zeaxanthin concentrations associated with genetic variations in SCARB1 and interactions between SCARB1 and sex. Results Following multiple regression analysis with adjustment for age, body mass index, sex, high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), triglycerides, smoking, dietary L and Z levels, 5 SNPs were significantly associated with serum L concentration and 1 SNP with MPOD (P<0.01). Only the association between rs11057841 and serum L withstood correction for multiple comparisons by permutation testing (P<0.01) and replicated in the TwinsUK cohort (P=0.014). Independent replication was also observed in the CAREDS cohort with rs10846744 (P=2×10−4), a SNP in high linkage disequilibrium with rs11057841 (r2=0.93). No significant interactions by sex were found. Haplotype analysis revealed no stronger association than obtained with single SNP analyses. Conclusions Our study has identified association between rs11057841 and serum L concentration (24% increase per T allele) in healthy subjects, independent of potential confounding factors. Our data supports further evaluation of the role for SCARB1 in the transport of macular pigment and the possible modulation of AMD risk through combating the effects of oxidative stress within the retina. PMID:23562302

Visualization and dissemination of multidimensional proteomics data comparing protein abundance during Caenorhabditis elegans development.

PubMed

Riffle, Michael; Merrihew, Gennifer E; Jaschob, Daniel; Sharma, Vagisha; Davis, Trisha N; Noble, William S; MacCoss, Michael J

2015-11-01

Regulation of protein abundance is a critical aspect of cellular function, organism development, and aging. Alternative splicing may give rise to multiple possible proteoforms of gene products where the abundance of each proteoform is independently regulated. Understanding how the abundances of these distinct gene products change is essential to understanding the underlying mechanisms of many biological processes. Bottom-up proteomics mass spectrometry techniques may be used to estimate protein abundance indirectly by sequencing and quantifying peptides that are later mapped to proteins based on sequence. However, quantifying the abundance of distinct gene products is routinely confounded by peptides that map to multiple possible proteoforms. In this work, we describe a technique that may be used to help mitigate the effects of confounding ambiguous peptides and multiple proteoforms when quantifying proteins. We have applied this technique to visualize the distribution of distinct gene products for the whole proteome across 11 developmental stages of the model organism Caenorhabditis elegans. The result is a large multidimensional dataset for which web-based tools were developed for visualizing how translated gene products change during development and identifying possible proteoforms. The underlying instrument raw files and tandem mass spectra may also be downloaded. The data resource is freely available on the web at http://www.yeastrc.org/wormpes/ . Graphical Abstract ᅟ.

Visualization and Dissemination of Multidimensional Proteomics Data Comparing Protein Abundance During Caenorhabditis elegans Development

NASA Astrophysics Data System (ADS)

Riffle, Michael; Merrihew, Gennifer E.; Jaschob, Daniel; Sharma, Vagisha; Davis, Trisha N.; Noble, William S.; MacCoss, Michael J.

2015-11-01

Regulation of protein abundance is a critical aspect of cellular function, organism development, and aging. Alternative splicing may give rise to multiple possible proteoforms of gene products where the abundance of each proteoform is independently regulated. Understanding how the abundances of these distinct gene products change is essential to understanding the underlying mechanisms of many biological processes. Bottom-up proteomics mass spectrometry techniques may be used to estimate protein abundance indirectly by sequencing and quantifying peptides that are later mapped to proteins based on sequence. However, quantifying the abundance of distinct gene products is routinely confounded by peptides that map to multiple possible proteoforms. In this work, we describe a technique that may be used to help mitigate the effects of confounding ambiguous peptides and multiple proteoforms when quantifying proteins. We have applied this technique to visualize the distribution of distinct gene products for the whole proteome across 11 developmental stages of the model organism Caenorhabditis elegans. The result is a large multidimensional dataset for which web-based tools were developed for visualizing how translated gene products change during development and identifying possible proteoforms. The underlying instrument raw files and tandem mass spectra may also be downloaded. The data resource is freely available on the web at http://www.yeastrc.org/wormpes/.

Vertebral hemangiomas in the thoracic spine of multiple sclerosis patients are connected with fewer demyelinating lesions at the same level. Possible impact on pathophysiology and clinical course.

PubMed

Anagnostouli, Maria; Katsavos, Serafeim; Kyrozis, Andreas; Gontika, Maria; Voumvourakis, Konstantinos I; Kapaki, Elisabeth

2016-08-01

Mechanisms of angiogenesis regulate multiple sclerosis (MS) lesions' evolution, displaying both neuroprotective and harmful effects. Factors traditionally considered as purely angiogenic, like vascular endothelial growth factor (VEGF), exert complex heterogenous actions on both neural and vascular malformation-derived tissues. Aim of this retrospective study was to examine, for the first time, potential associations between the presence of common vascular malformations, like vertebral hemangiomas (VHs), and several clinico-radiological MS parameters. 236 MS patients who were followed in our Outpatient Clinic were recruited in this study. Outcome measures concerned demographics, disease-derived variables, and MS-lesions' distribution in VHs - positive and negative patients. All data were collected retrospectively. Potential correlations were assessed with univariate statistical analyses (p = 0.05), followed by multivariate regression models, for purposes of confounder-effects elimination. VH presence showed significant negative correlations with presence of MS lesions in the thoracic (p = 0.005 for thoracic VHs), but not the cervical cord. Trends towards negative associations of VH presence with subtentorial MS lesions and positive family history for MS were also observed. Our observations suggest that VH presence may reduce the risk of thoracic demyelinating lesions in MS patients. They could be explained as part of a multifaceted angiogenic process, concomitantly enhancing neural repair and abnormal hemangioma vascularization.

Disruptions in Energy Balance: Does Nature overcome Nurture?

PubMed Central

Fernández, José R.; Casazza, Krista; Divers, Jasmin; López-Alarcón, Mardya

2008-01-01

Fat accumulation, in general, is the result of a breakdown in the homeostatic regulation of energy balance. Although, the specific factors influencing the disruption of energy balance and why these factors affect individuals differently are not completely understood, numerous studies have identified multiple contributors. Environmental components influence food acquisition, eating, and lifestyle habits. However, the variability in obesity-related outcomes observed among individuals placed in similar controlled environments support the notion that genetic components also wield some control. Multiple genetic regions have been associated with measures related to energy balance; however, the replication of these genetic contributors to energy intake and energy expenditure in humans is relatively small perhaps because of the heterogeneity of human populations. Genetic tools such as genetic admixture account for individual’s genetic background in gene association studies, reducing the confounding effect of population stratification, and promise to be a relevant tool on the identification of genetic contributions to energy balance, particularly among individuals of diverse racial/ethnic backgrounds. Although it has been recognized that genes are expressed according to environmental influences, the search toward the understanding of nature and nurture in obesity will require the detailed study of the effect of genes under diverse physiologic and behavioral environments. It is evident that more research is needed to elucidate the methodological and statistical issues that underlie the interactions between genes and environments in obesity and its related comorbidities. PMID:18096193

Risk profiles for weight gain among postmenopausal women: A classification and regression tree analysis approach

USDA-ARS?s Scientific Manuscript database

Risk factors for obesity and weight gain are typically evaluated individually while "adjusting for" the influence of other confounding factors, and few studies, if any, have created risk profiles by clustering risk factors. We identified subgroups of postmenopausal women homogeneous in their cluster...

N-acetyltransferase single nucleotide polymorphisms: Emerging concepts serve as a paradigm for understanding complexities of personalized medicine

PubMed Central

Hein, David W.

2009-01-01

Arylamine N-acetyltransferase 1 (NAT1) and 2 (NAT2) exhibit single nucleotide polymorphisms (SNPs) in human populations that modify drug and carcinogen metabolism. This paper updates the identity, location, and functional effects of these SNPs and then follows with emerging concepts for understanding why pharmacogenetic findings may not be replicated consistently. Using this paradigm as an example, laboratory-based mechanistic analyses can reveal complexities such that genetic polymorphisms become biologically and medically relevant when confounding factors are more fully understood and considered. As medical care moves to a more personalized approach, the implications of these confounding factors will be important in understanding the complexities of personalized medicine. PMID:19379125

Breast milk and cognitive development—the role of confounders: a systematic review

PubMed Central

Walfisch, Asnat; Sermer, Corey; Cressman, Alex; Koren, Gideon

2013-01-01

Objectives The association between breastfeeding and child cognitive development is conflicted by studies reporting positive and null effects. This relationship may be confounded by factors associated with breastfeeding, specifically maternal socioeconomic class and IQ. Design Systematic review of the literature. Setting and participants Any prospective or retrospective study, in any language, evaluating the association between breastfeeding and cognitive development using a validated method in healthy term infants, children or adults, was included. Primary and secondary outcome measures Extracted data included the study design, target population and sample size, breastfeeding exposure, cognitive development assessment tool used and participants’ age, summary of the results prior to, and following, adjustment for confounders, and all confounders adjusted for. Study quality was assessed as well. Results 84 studies met our inclusion criteria (34 rated as high quality, 26 moderate and 24 low quality). Critical assessment of accepted studies revealed the following associations: 21 null, 28 positive, 18 null after adjusting for confounders and 17 positive—diminished after adjusting for confounders. Directionality of effect did not correlate with study quality; however, studies showing a decreased effect after multivariate analysis were of superior quality compared with other study groupings (14/17 high quality, 82%). Further, studies that showed null or diminished effect after multivariate analysis corrected for significantly more confounders (7.7±3.4) as compared with those that found no change following adjustment (5.6±4.5, p=0.04). The majority of included studies were carried out during childhood (75%) and set in high-income countries (85.5%). Conclusions Much of the reported effect of breastfeeding on child neurodevelopment is due to confounding. It is unlikely that additional work will change the current synthesis. Future studies should attempt to rigorously control for all important confounders. Alternatively, study designs using sibling cohorts discordant for breastfeeding may yield more robust conclusions. PMID:23975102

On the use and misuse of scalar scores of confounders in design and analysis of observational studies.

PubMed

Pfeiffer, R M; Riedl, R

2015-08-15

We assess the asymptotic bias of estimates of exposure effects conditional on covariates when summary scores of confounders, instead of the confounders themselves, are used to analyze observational data. First, we study regression models for cohort data that are adjusted for summary scores. Second, we derive the asymptotic bias for case-control studies when cases and controls are matched on a summary score, and then analyzed either using conditional logistic regression or by unconditional logistic regression adjusted for the summary score. Two scores, the propensity score (PS) and the disease risk score (DRS) are studied in detail. For cohort analysis, when regression models are adjusted for the PS, the estimated conditional treatment effect is unbiased only for linear models, or at the null for non-linear models. Adjustment of cohort data for DRS yields unbiased estimates only for linear regression; all other estimates of exposure effects are biased. Matching cases and controls on DRS and analyzing them using conditional logistic regression yields unbiased estimates of exposure effect, whereas adjusting for the DRS in unconditional logistic regression yields biased estimates, even under the null hypothesis of no association. Matching cases and controls on the PS yield unbiased estimates only under the null for both conditional and unconditional logistic regression, adjusted for the PS. We study the bias for various confounding scenarios and compare our asymptotic results with those from simulations with limited sample sizes. To create realistic correlations among multiple confounders, we also based simulations on a real dataset. Copyright © 2015 John Wiley & Sons, Ltd.

Self-efficacy difference among patients with cancer with different socioeconomic status: application of latent class analysis and standardization and decomposition analysis.

PubMed

Yuan, Changrong; Wei, Chunlan; Wang, Jichuan; Qian, Huijuan; Ye, Xianghong; Liu, Yingyan; Hinds, Pamela S

2014-06-01

Although the relationship between partial socioeconomic status (SES) and self-efficacy has been studied in previous studies, few research have examined self-efficacy difference among patients with cancer with different SES. A cross-sectional survey involving 764 patients with cancer was completed. Latent class analysis (LCA) was applied to identify distinct groups of patients with cancer using four SES indicators (education, income, employment status and health insurance status). Standardization and decomposition analysis (SDA) was then used to examine differences in patients' self-efficacy among SES groups and the components of the differences attributed to confounding factors, such as gender, age, anxiety, depression and social support. Participants were classified into four distinctive SES groups via using LCA method, and the observed self-efficacy level significantly varied by SES groups; as theorized, higher self-efficacy was associated with higher SES. The self-efficacy differences by SES groups were decomposed into "real" group differences and factor component effects that are attributed to group differences in confounding factor compositions. Self-efficacy significantly varies by SES. Social support significantly confounded the observed differences in self-efficacy between different SES groups among Chinese patients with cancer. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fatigue in Patients with Multiple Sclerosis: Is It Related to Pro- and Anti-Inflammatory Cytokines?

PubMed Central

Malekzadeh, Arjan; Van de Geer-Peeters, Wietske; De Groot, Vincent; Elisabeth Teunissen, Charlotte; Beckerman, Heleen; TREFAMS-ACE Study Group

2015-01-01

Objective. To investigate the pathophysiological role of pro- and anti-inflammatory cytokines in primary multiple sclerosis-related fatigue. Methods. Fatigued and non-fatigued patients with multiple sclerosis (MS) were recruited and their cytokine profiles compared. Patients with secondary fatigue were excluded. Fatigue was assessed with the self-reported Checklist Individual Strength (CIS20r), subscale fatigue. A CIS20r fatigue cut-off score of 35 was applied to differentiate between non-fatigued (CIS20r fatigue ≤34) and fatigued (CIS20r fatigue ≥35) patients with MS. Blood was collected to determine the serum concentrations of pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IL-8, IL-12p70, IL-17, TNFα, and IFN-γ) and anti-inflammatory cytokines (IL-4, IL-5, IL-10, and IL-13). We controlled for the confounding effect of age, gender, duration of MS, disease severity, type of MS, and use of immunomodulatory drugs. Results. Similar cytokine levels were observed between MS patients with (n = 21) and without fatigue (n = 14). Adjusted multiple regression analyses showed a single significant positive relationship, that of IL-6 with CIS20r fatigue score. The explained variance of the IL-6 model was 21.1%, once adjusted for the confounding effect of age. Conclusion. The pro-inflammatory cytokine interleukin-6 (IL-6) may play a role in the pathophysiology of primary fatigue in patients with MS. Trial Registrations. ISRCTN69520623, ISRCTN58583714, and ISRCTN82353628. PMID:25722532

Is Geo-Environmental Exposure a Risk Factor for Multiple Sclerosis? A Population-Based Cross-Sectional Study in South-Western Sardinia.

PubMed

Monti, Maria Cristina; Guido, Davide; Montomoli, Cristina; Sardu, Claudia; Sanna, Alessandro; Pretti, Salvatore; Lorefice, Lorena; Marrosu, Maria Giovanna; Valera, Paolo; Cocco, Eleonora

South-Western Sardinia (SWS) is a high risk area for Multiple Sclerosis (MS) with high prevalence and spatial clustering; its population is genetically representative of Sardinians and presents a peculiar environment. We evaluated the MS environmental risk of specific heavy metals (HM) and geographical factors such as solar UV exposure and urbanization by undertaking a population-based cross-sectional study in SWS. Geochemical data on HM, UV exposure, urbanization and epidemiological MS data were available for all SWS municipalities. Principal Component Analysis (PCA) was applied to the geochemical data to reduce multicollinearity and confounding criticalities. Generalized Linear Mixed Models (GLMM) were applied to evaluate the causal effects of the potential risk factors, and a model selection was performed using Akaike Information Criterion. The PCA revealed that copper (Cu) does not cluster, while two component scores were extracted: 'basic rocks', including cobalt, chromium and nickel, and 'ore deposits', including lead and zinc. The selected multivariable GLMM highlighted Cu and sex as MS risk factors, adjusting for age and 'ore deposits'. When the Cu concentration increases by 50 ppm, the MS odds are 2.827 (95% CI: 1.645; 5.07) times higher; females have a MS odds 2.04 times (95% CI: 1.59; 2.60) higher than males. The high frequency of MS in industrialized countries, where pollution by HM and CO poisoning is widespread, suggests a relationship between environmental exposure to metals and MS. Hence, we suggested a role of Cu homeostasis in MS. This is a preliminary study aimed at generating hypotheses that will need to be confirmed further.

An Evidence-Based Approach to an Adolescent with Emotional and Behavioral Dysregulation

ERIC Educational Resources Information Center

McClellan, Jon M.; Hamilton, John D.

2006-01-01

Children and adolescents in community mental health settings often present with multiple overlapping syndromes, as well as confounding issues such as family turmoil, abuse and neglect, and involvement with social welfare and juvenile justice systems. Most interventions proven to have efficacy in randomized, controlled trials have nevertheless not…

Learning and Motivational Benefits of Acronym Use in Introductory Psychology

ERIC Educational Resources Information Center

Stalder, Daniel R.

2005-01-01

Study 1 assessed students' use and perceptions of acronyms at 3 different exam times in 2 sections of Introduction to Psychology. Acronym use consistently predicted higher performance on acronym related exam items, and I partially discounted 2 possible confounds. Students rated acronyms as helpful in multiple ways, including increasing motivation…

An empirical study of rape in the context of multiple murder.

PubMed

DeLisi, Matt

2014-03-01

In recent years, multiple homicide offending has received increased research attention from criminologists; however, there is mixed evidence about the role of rape toward the perpetration of multiple murder. Drawing on criminal career data from a nonprobability sample of 618 confined male homicide offenders selected from eight U.S. states, the current study examines the role of rape as a predictor of multiple homicide offending. Bivariate analyses indicated a significant association between rape and murder charges. Multivariate path regression models indicated that rape had a significant and robust association with multiple murder. This relationship withstood the confounding effects of kidnapping, prior prison confinement, and prior murder, rape, and kidnapping. These results provide evidence that rape potentially serves as a gateway to multiple murder for some serious offenders. Suggestions for future research are proffered.

Prospective cohort study of factors influencing the relative weights of the placenta and the newborn infant.

PubMed

Williams, L A; Evans, S F; Newnham, J P

1997-06-28

To determine the demographic, environmental, and medical factors that influence the relative weights of the newborn infant and the placenta and compare this ratio with other factors known to predispose to adult ill health. Prospective cohort study. The tertiary referral centre for perinatal care in Perth, Western Australia. 2507 pregnant women who delivered a single live infant at term. Placental weight, birth weight, and the ratio of placental weight to birth weight. By multiple regression analysis the placental weight to birthweight ratio was significantly and positively associated with gestational age, female sex, Asian parentage, increasing maternal body mass index, increased maternal weight at booking, lower socioeconomic status, maternal anaemia, and increasing number of cigarettes smoked daily. There were no consistent relations between the placental weight to birthweight ratio and measures of newborn size. The ratio of placental weight to birth weight is not an accurate marker of fetal growth. In its role as a predictor of adult disease the ratio may be acting as a surrogate for other factors which are already known to influence health and may act before or after birth. Determining the role that relative growth rates of the fetus and placenta have in predisposing to adult disease requires prospective study to account for the many confounding variables which complicate this hypothesis.

American Visceral Leishmaniasis: Factors Associated with Lethality in the State of São Paulo, Brazil

PubMed Central

Madalosso, Geraldine; Fortaleza, Carlos Magno; Ribeiro, Ana Freitas; Cruz, Lisete Lage; Nogueira, Péricles Alves; Lindoso, José Angelo Lauletta

2012-01-01

Objectives. To identify factors associated with death in visceral leishmaniasis (VL) cases. Patients and Methodology. We evaluated prognostic factors for death from VL in São Paulo state, Brazil, from 1999 to 2005. A prognostic study nested in a clinical cohort was carried out by data analysis of 376 medical files. A comparison between VL fatal cases and survivors was performed for clinical, laboratory, and biological features. Association between variables and death was assessed by univariate analysis, and the multiple logistic regression model was used to determine adjusted odds ratio for death, controlling confounding factors. Results. Data analysis identified 53 fatal cases out of 376 patients, between 1999 and 2005 in São Paulo state. Lethality was 14.1% (53/376), being higher in patients older than fifty years. The main causes of death were sepsis, bleeding, liver failure, and cardiotoxicity due to treatment. Variables significantly associated with death were severe anemia, bleeding, heart failure, jaundice, diarrhea, fever for more than sixty days, age older than fifty years, and antibiotic use. Conclusion. Educational health measures are needed for the general population and continuing education programs for health professionals working in the affected areas with the purpose of identifying and treating early cases, thus preventing the disease evolution towards death. PMID:23024661

[Mother-child relationship and associated factors: Hierarchical analysis of the population base in a Brazilian state capital - BRISA Study].

PubMed

Cavalcante, Milady Cutrim Vieira; Lamy, Fernando; França, Ana Karina Teixeira da Cunha; Lamy, Zeni Carvalho

2017-05-01

Several factors can interfere in the mother-child relationship. Studies about different maternal characteristics and this relationship are scarce; they mainly evaluate women with psychopathology and use simultaneous regression models with adjustment for multiple confounders. This study aimed to assess factors associated with losses in the mother-child relationship through a cohort of 3,215 mothers of children between 15 and 36 months of age. Losses in the mother-child relationship, assessed by the Postpartum Bonding Questionnaire, was the outcome variable and the explanatory variables were demographic, socioeconomic, reproductive health and mental health of mothers as well as the conditions of the birth of children. It used multivariate regression analysis with a hierarchical approach in which the hierarchical blocks were structured according to the influence on the mother-child relationship. The prevalence of losses in the mother-child relationship was high (12.6%) and associated risk factors to lower maternal education (RR = 1.64), having unplanned pregnancy (RR = 1.42), consumption of alcoholic beverages during pregnancy (RR = 1.42) and maternal stress symptoms (RR = 1.88) and depression (RR = 2.00). Education and elements related to mental health were risks for damage in the mother-child relationship.

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.

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.

Oxidative stress in drug-naïve first episode patients with schizophrenia and major depression: effects of disease acuity and potential confounders.

PubMed

Jordan, Wolfgang; Dobrowolny, Henrik; Bahn, Sabine; Bernstein, Hans-Gert; Brigadski, Tanja; Frodl, Thomas; Isermann, Berend; Lessmann, Volkmar; Pilz, Jürgen; Rodenbeck, Andrea; Schiltz, Kolja; Schwedhelm, Edzard; Tumani, Hayrettin; Wiltfang, Jens; Guest, Paul C; Steiner, Johann

2018-03-01

Oxidative stress and immune dysregulation have been linked to schizophrenia and depression. However, it is unknown whether these factors are related to the pathophysiology or whether they are an epiphenomenon. Inconsistent oxidative stress-related findings in previous studies may have resulted from the use of different biomarkers which show disparate aspects of oxidative stress. Additionally, disease severity, medication, smoking, endocrine stress axis activation and obesity are potential confounders. In order to address some of these shortcomings, we have analyzed a broader set of oxidative stress biomarkers in our exploratory study, including urinary 8-iso-prostaglandin F2α (8-iso-PGF2α), 8-OH-2-deoyxguanosine (8-OH-2-dG), and blood levels of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione S-transferase (GST) in acutely ill drug-naïve first episode patients with schizophrenia (n = 22), major depression (n = 18), and controls (n = 43). Possible confounding factors were considered, and patients were followed-up after 6 weeks of treatment. No differences were observed regarding 8-OH-2-dG, MDA and GST. At baseline, 8-iso-PGF2α levels were higher in patients with schizophrenia (p = 0.004) and major depression (p = 0.037), with a trend toward higher SOD concentrations in schizophrenia (p = 0.053). After treatment, schizophrenia patients showed a further increase in 8-iso-PGF2α (p = 0.016). These results were not related to age, sex, disease severity, medication or adipose tissue mass. However, 8-iso-PGF2α was associated with smoking, endocrine stress axis activation, C-reactive protein levels and low plasma concentrations of brain-derived neurotrophic factor. This study suggests a role of lipid peroxidation particularly in drug-naïve acutely ill schizophrenia patients and highlights the importance of taking into account other confounding factors in biomarker studies.

Correlation of worldwide incidence of type 1 diabetes (DiaMond) with prevalence of asthma and atopic eczema (ISAAC).

PubMed

Fsadni, Peter; Fsadni, Claudia; Fava, Stephen; Montefort, Stephen

2012-01-01

Environmental factors play a role in pathogenesis of both type 1 diabetes and atopic disease but they remain incompletely understood. T cell-mediated responses primarily of the T helper type 1 (Th1) are involved in type 1 diabetes while T helper type 2 (Th2) responses favour allergic disease. This TH 1/TH 2 paradigm is currently the source of much controversy in various studies. The aim of the study was to compare the reported country incidence of type 1 diabetes with the prevalence of atopic disease. The prevalence of wheeze, rhinitis, rhinoconjunctivitis and atopic eczema in the preceding 12 months in the 13- to 14-year-old age group was taken from The International Study of Asthma and Allergies in Childhood phase 1 study. These were compared to the age specific incidence of type 1 diabetes in children per 100 000 per year obtained from the Diabetes Mondiale Project Group study from those countries participating in both studies. Data collected from these 31 countries together with latitude was analysed using a Pearson correlation and significance analysis. A multiple regression analysis determined the confounding effect of latitude. The incidence of type 1 diabetes was found to have a positive correlation with both wheezing (P = 0.009) and atopic eczema (P < 0.01). There was a no correlation between the incidence of type 1 diabetes and the prevalance of rhinitis (r = 0.02, P = 0.88) or of rhinoconjunctivitis (r = 0.026, P = 0.88). Latitude correlated negatively with type 1 diabetes and positively with rhinitis and rhinoconjnctuvits; it was not significantly correlated with wheeze or eczema. Regression analysis showed that latitude is a significant confounding factor in the correlation of rhinitis (P value < 0.0008) and rhinoconjunctivitis (P value < 0.0003) with diabetes. The study suggests that common environmental and/or genetic factors predispose to type 1 diabetes, wheezing and atopic eczema while factors predisposing to rhinitis and rhinoconjunctivitis appear to be distinct from those predisposing to type 1 diabetes. © 2011 Blackwell Publishing Ltd.

Adult Body Height Is a Good Predictor of Different Dimensions of Cognitive Function in Aged Individuals: A Cross-Sectional Study.

PubMed

Pereira, Vitor H; Costa, Patrício S; Santos, Nadine C; Cunha, Pedro G; Correia-Neves, Margarida; Palha, Joana A; Sousa, Nuno

2016-01-01

Background: Adult height, weight, and adiposity measures have been suggested by some studies to be predictors of depression, cognitive impairment, and dementia. However, the presence of confounding factors and the lack of a thorough neuropsychological evaluation in many of these studies have precluded a definitive conclusion about the influence of anthropometric measures in cognition and depression. In this study we aimed to assess the value of height, weight, and abdominal perimeter to predict cognitive impairment and depressive symptoms in aged individuals. Methods and Findings: Cross-sectional study performed between 2010 and 2012 in the Portuguese general community. A total of 1050 participants were included in the study and randomly selected from local area health authority registries. The cohort was representative of the general Portuguese population with respect to age (above 50 years of age) and gender. Cognitive function was assessed using a battery of tests grouped in two dimensions: general executive function and memory. Two-step hierarchical multiple linear regression models were conducted to determine the predictive value of anthropometric measures in cognitive performance and mood before and after correction for possible confounding factors (gender, age, school years, physical activity, alcohol consumption, and smoking habits). We found single associations of weight, height, body mass index, abdominal perimeter, and age with executive function, memory and depressive symptoms. However, when included in a predictive model adjusted for gender, age, school years, and lifestyle factors only height prevailed as a significant predictor of general executive function (β = 0.139; p < 0.001) and memory (β = 0.099; p < 0.05). No relation was found between mood and any of the anthropometric measures studied. Conclusions and Relevance: Height is an independent predictor of cognitive function in late-life and its effects on the general and executive function and memory are independent of age, weight, education level, gender, and lifestyle factors. Altogether, our data suggests that modulators of adult height during childhood may irreversibly contribute to cognitive function in adult life and that height should be used in models to predict cognitive performance.

Multiple roles and all-cause mortality: the Japan Collaborative Cohort Study.

PubMed

Tamakoshi, Akiko; Ikeda, Ai; Fujino, Yoshihisa; Tamakoshi, Koji; Iso, Hisoyasu

2013-02-01

Two contrasting perspectives on the effects of multiple roles; the 'role overload hypothesis' and the 'role enhancement model', have been proposed to predict variations in health. The aim of this study was to evaluate the impact of multiple roles on all-cause mortality in Japan where gender roles are currently changing. A total of 76,758 individuals from the Japan Collaborative Cohort Study were followed for an average of 15.7 years. Hazard ratios (HRs) with 95% confidence intervals were calculated from proportional hazard models to estimate the risk of all-cause mortality according to multiple roles (spouse, parent and worker, and combinations of these roles). After adjusting for potential confounding factors, the risks of all-cause mortality were elevated among men and women without a role. The number of roles was also associated with all-cause mortality risk, showing the highest risk values among those with no roles compared with those with triple roles (HR: 1.66 in men and 1.78 in women). The impact of the lack of a role was generally greater in men than in women and also in the middle-aged than in the elderly. A beneficial effect of multiple roles was suggested among Japanese. The fewer roles they had, the higher all-cause mortality risks were observed. The risk values of those with fewer roles were generally higher in men than in women and also in the middle-aged than in the elderly, partially explained by greater role overload in middle-aged women than other groups in Japan.

Thyroid STAtus and 6-Year Mortality in Elderly People Living in a Mildly Iodine-Deficient Area: The Aging in the Chianti Area (InCHIANTI) Study

PubMed Central

Ceresini, Graziano; Ceda, Gian Paolo; Lauretani, Fulvio; Maggio, Marcello; Usberti, Elisa; Marina, Michela; Bandinelli, Stefania; Guralnik, Jack M.; Valenti, Giorgio; Ferrucci, Luigi

2013-01-01

Objectives The relationship between thyroid dysfunction and mortality in elderly subjects is still undefined. In this population study we tested the hypothesis that in older subjects, living in a mildly iodine-deficient area, thyroid dysfunction may be associated with increased mortality independent of potential confounders. Design Longitudinal study Setting Community-based Participants Total of 951 subjects aged 65 years and older Measurements Plasma thyrotropin (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) concentrations and demographic features were evaluated in participants of the Aging in the Chianti Area (InCHIANTI) study, aged 65 years or older. Participants were classified according to thyroid function test. Kaplan-Meier survival and Cox proportional hazards models adjusted for confounders were used in the analysis. Results A total of 819 participants were euthyroid, 83 had Subclinical hyperthyroidism (SHyper), and 29 had Subclinical hypothyroidism (SHypo). Overt Hypo- and Hyperthyroidism were found in 5 and 15 subjects, respectively. During a median of six-years of follow-up, N 210 deaths occurred (22.1 %) of which 98 (46.6%) due to cardiovascular causes. Kaplan–Meier analysis revealed higher overall mortality for SHyper (P<0.04) as compared to euthyroid subjects. After adjusting for multiple confounders, participants with SHyper (Hazard Ratio[HR]:1.65; 95% Confidence Interval [CI]: 1.02–2.69) had significantly higher all-cause mortality than those with normal thyroid function. No significant association was found between SHyper and cardiovascular mortality. In euthyroid subjects, TSH was found to be predictive of a reduced risk of all-cause mortality (HR: 0.76; 95% CI, 0.57–0.99) Conclusion SHyper is an independent risk factor for all-cause mortality in the older population. Low-normal circulating TSH should be carefully monitored in euthyroid elderly individuals. PMID:23647402

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.

Low cardiorespiratory fitness in young adulthood and future risk of disability pension: a follow-up study until 59 years of age in Swedish men.

PubMed

Rabiee, Rynaz; Agardh, Emilie; Kjellberg, Katarina; Falkstedt, Daniel

2015-03-01

There is a strong belief in the potential of increased physical activity to improve the health of populations. The objective of the present study was to estimate the association between low cardiorespiratory fitness in young adulthood and subsequent health impairment until middle age, measured by disability pension. The study utilised data on cardiorespiratory fitness and a number of covariates (social background, health behaviours and psychological characteristics) from the Swedish Conscription Cohort of 1969/1970 including 49,321 men born in 1949-1951, and data on disability pension from 1971 to 2008 (20-59 years of age) through record linkage with two national insurance databases. Cox proportional-hazards regressions yielded hazard ratios (HR) with 95% confidence intervals (CI). Having low-level or mid-level cardiorespiratory fitness in late adolescence was associated with an increased HR of disability pension across the follow-up (HR for low fitness: 1.85, CI 1.71 to 2.00; HR for mid-level fitness: 1.40, CI 1.31 to 1.50). The association was stronger with earlier disability pensions than with later disability pensions, which was also seen after multiple confounding adjustments. At the same time, these adjustments revealed considerable confounding of the association by individual differences in psychological characteristics in particular. Lower levels of cardiorespiratory fitness in young adulthood were found to be associated with an increased HR of disability pension throughout the follow-up until 59 years of age, even after adjustment for important confounding factors measured in late adolescence. Increased physical fitness may thus have a lowering effect on the risk of disability pension. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Association of urinary sodium/creatinine ratio with bone mineral density in postmenopausal women: KNHANES 2008-2011.

PubMed

Kim, Sung-Woo; Jeon, Jae-Han; Choi, Yeon-Kyung; Lee, Won-Kee; Hwang, In-Ryang; Kim, Jung-Guk; Lee, In-Kyu; Park, Keun-Gyu

2015-08-01

Accumulating evidence shows that high sodium chloride intake increases urinary calcium excretion and may be a risk factor for osteoporosis. However, the effect of oral sodium chloride intake on bone mineral density (BMD) and risk of osteoporosis has been inadequately researched. The aim of the present study was to determine whether urinary sodium excretion (reflecting oral sodium chloride intake) associates with BMD and prevalence of osteoporosis in postmenopausal women. This cross-sectional study involved a nationally representative sample consisting of 2,779 postmenopausal women who participated in the Korea National Health and Nutritional Examination Surveys in 2008-2011. The association of urinary sodium/creatinine ratio with BMD and other osteoporosis risk factors was assessed. In addition, the prevalence of osteoporosis was assessed in four groups with different urinary sodium/creatinine ratios. Participants with osteoporosis had significantly higher urinary sodium/creatinine ratios than the participants without osteoporosis. After adjusting for multiple confounding factors, urinary sodium/creatinine ratio correlated inversely with lumbar spine BMD (P = 0.001). Similarly, when participants were divided into quartile groups according to urinary sodium/creatinine ratio, the average BMD dropped as the urinary sodium/creatinine ratio increased. Multiple logistic regression analysis revealed that compared to quartile 1, quartile 4 had a significantly increased prevalence of lumbar spine osteoporosis (odds ratios 1.346, P for trend = 0.044). High urinary sodium excretion was significantly associated with low BMD and high prevalence of osteoporosis in lumbar spine. These results suggest that high sodium chloride intake decreases lumbar spine BMD and increases the risk of osteoporosis in postmenopausal women.

Food Environments and Obesity: Household Diet Expenditure Versus Food Deserts

PubMed Central

Jaenicke, Edward C.; Volpe, Richard J.

2016-01-01

Objectives. To examine the associations between obesity and multiple aspects of the food environments, at home and in the neighborhood. Methods. Our study included 38 650 individuals nested in 18 381 households located in 2104 US counties. Our novel home food environment measure, USDAScore, evaluated the adherence of a household’s monthly expenditure shares of 24 aggregated food categories to the recommended values based on US Department of Agriculture food plans. The US Census Bureau’s County Business Patterns (2008), the detailed food purchase information in the IRi Consumer Panel scanner data (2008–2012), and its associated MedProfiler data set (2012) constituted the main sources for neighborhood-, household-, and individual-level data, respectively. Results. After we controlled for a number of confounders at the individual, household, and neighborhood levels, USDAScore was negatively linked with obesity status, and a census tract–level indicator of food desert status was positively associated with obesity status. Conclusions. Neighborhood food environment factors, such as food desert status, were associated with obesity status even after we controlled for home food environment factors. PMID:26985622

Neuromotor outcomes in infants with bronchopulmonary dysplasia.

PubMed

Karagianni, Paraskevi; Tsakalidis, Christos; Kyriakidou, Maria; Mitsiakos, Georgios; Chatziioanidis, Helias; Porpodi, Maria; Evangeliou, Athanasios; Nikolaides, Nikolaos

2011-01-01

We examine the neuromotor outcomes of preterm infants with bronchopulmonary dysplasia. Two hundred and nineteen infants (gestational age, ≤ 32 weeks; birth weight, ≤ 1500 g) were studied. Neuromotor development was assessed using the Hammersmith Infant Neurological Examination. All potential risk factors associated with neuromotor scores (P < 0.015) were included in the generalized linear model (multiple linear regression) to determine if bronchopulmonary dysplasia had an independent relationship with neuromotor scores. Infants with severe bronchopulmonary dysplasia had lower global scores at ages 6 and 12 months. After adjustment for confounding factors, scores of infants with severe bronchopulmonary dysplasia were reduced by 13.2 units, whereas scores for those with periventricular leukomalacia were reduced by 11.1 units, at age 6 months. At age 12 months, scores for those with periventricular leukomalacia were reduced by 11.9 units. Duration of hospital stay reduced scores by 0.1 for each additional day increase in hospital. Bronchopulmonary dysplasia constitutes a major cause of poor neuromotor outcomes at age 6 months, but improvements in motor outcomes occur over time. Copyright © 2011 Elsevier Inc. All rights reserved.

Prediction versus aetiology: common pitfalls and how to avoid them.

PubMed

van Diepen, Merel; Ramspek, Chava L; Jager, Kitty J; Zoccali, Carmine; Dekker, Friedo W

2017-04-01

Prediction research is a distinct field of epidemiologic research, which should be clearly separated from aetiological research. Both prediction and aetiology make use of multivariable modelling, but the underlying research aim and interpretation of results are very different. Aetiology aims at uncovering the causal effect of a specific risk factor on an outcome, adjusting for confounding factors that are selected based on pre-existing knowledge of causal relations. In contrast, prediction aims at accurately predicting the risk of an outcome using multiple predictors collectively, where the final prediction model is usually based on statistically significant, but not necessarily causal, associations in the data at hand.In both scientific and clinical practice, however, the two are often confused, resulting in poor-quality publications with limited interpretability and applicability. A major problem is the frequently encountered aetiological interpretation of prediction results, where individual variables in a prediction model are attributed causal meaning. This article stresses the differences in use and interpretation of aetiological and prediction studies, and gives examples of common pitfalls. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Risk of Breast Cancer Associated with Reproductive and Fertility Factors According to a Family History of Breast Cancer

DTIC Science & Technology

1999-10-01

also ruled out as confounders. Polycystic ovaries and endometriosis, possible indications for using OCs, were evaluated as potential confounders, but...Cn polymorphism In the MTHFR gone with breast and/or A irne genomic deletion of hMLHI in a family with Muir-Torre syndrome . J.J.P.canoer risk In...reduion I te,1Teth-A Muir-Torre syndrome (MTS) is an autosomal dominant condition characterized by se- Miylonetetrathydrofoiate reductase (MTHFR

Systematic review of the quality of prognosis studies in systemic lupus erythematosus.

PubMed

Lim, Lily S H; Lee, Senq J; Feldman, Brian M; Gladman, Dafna D; Pullenayegum, Eleanor; Uleryk, Elizabeth; Silverman, Earl D

2014-10-01

Prognosis studies examine outcomes and/or seek to identify predictors or factors associated with outcomes. Many prognostic factors have been identified in systemic lupus erythematosus (SLE), but few have been consistently found across studies. We hypothesized that this is due to a lack of rigor of study designs. This study aimed to systematically assess the methodologic quality of prognosis studies in SLE. A search of prognosis studies in SLE was performed using MEDLINE and Embase, from January 1990 to June 2011. A representative sample of 150 articles was selected using a random number generator and assessed by 2 reviewers. Each study was assessed by a risk of bias tool according to 6 domains: study participation, study attrition, measurement of prognostic factors, measurement of outcomes, measurement/adjustment for confounders, and appropriateness of statistical analysis. Information about missing data was also collected. A cohort design was used in 71% of studies. High risk of bias was found in 65% of studies for confounders, 57% for study participation, 56% for attrition, 36% for statistical analyses, 20% for prognostic factors, and 18% for outcome. Missing covariate or outcome information was present in half of the studies. Only 6 studies discussed reasons for missing data and 2 imputed missing data. Lack of rigorous study design, especially in addressing confounding, study participation and attrition, and inadequately handled missing data, has limited the quality of prognosis studies in SLE. Future prognosis studies should be designed with consideration of these factors to improve methodologic rigor. Copyright © 2014 by the American College of Rheumatology.

Meeting Report--NASA Radiation Biomarker Workshop

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

Straume, Tore; Amundson, Sally A,; Blakely, William F.

2008-05-01

A summary is provided of presentations and discussions from the NASA Radiation Biomarker Workshop held September 27-28, 2007, at NASA Ames Research Center in Mountain View, California. Invited speakers were distinguished scientists representing key sectors of the radiation research community. Speakers addressed recent developments in the biomarker and biotechnology fields that may provide new opportunities for health-related assessment of radiation-exposed individuals, including for long-duration space travel. Topics discussed include the space radiation environment, biomarkers of radiation sensitivity and individual susceptibility, molecular signatures of low-dose responses, multivariate analysis of gene expression, biomarkers in biodefense, biomarkers in radiation oncology, biomarkers and triagemore » following large-scale radiological incidents, integrated and multiple biomarker approaches, advances in whole-genome tiling arrays, advances in mass-spectrometry proteomics, radiation biodosimetry for estimation of cancer risk in a rat skin model, and confounding factors. Summary conclusions are provided at the end of the report.« less

[Homicide mortality, socioeconomic development, and police violence in the city of São Paulo, Brazil].

PubMed

Peres, Maria Fernanda Tourinho; Cardia, Nancy; de Mesquita Neto, Paulo; Dos Santos, Patrícia Carla; Adorno, Sérgio

2008-04-01

To analyze the association between police violence and homicide mortality rates taking into consideration the effect of contextual variables. This was an environmental, cross-sectional study that included the 96 census districts in the City of São Paulo. The association between the variables was analyzed using Spearman's rank correlation and simple and multiple regression analysis. Univariate analysis revealed a strong and significant association between homicide mortality coefficients and all the indicators of socioeconomic development and police violence. After controlling for potential confounding factors, the association between police violence and homicide mortality coefficients remained strong and significant. This significance was lost only after control for the size of the resident population. The results indicate that police action that violates basic human rights is not the right answer to urban violence. The combination of homicides from interpersonal violence and deaths from police violence results in negative socialization and promotes further violence.

The loss of episodic memories in retrograde amnesia: single-case and group studies.

PubMed

Kopelman, M D; Kapur, N

2001-09-29

Retrograde amnesia in neurological disorders is a perplexing and fascinating research topic. The severity of retrograde amnesia is not well correlated with that of anterograde amnesia, and there can be disproportionate impairments of either. Within retrograde amnesia, there are various dissociations which have been claimed-for example, between the more autobiographical (episodic) and more semantic components of memory. However, the associations of different types of retrograde amnesia are also important, and clarification of these issues is confounded by the fact that retrograde amnesia seems to be particularly vulnerable to psychogenic factors. Large frontal and temporal lobe lesions have been postulated as critical in producing retrograde amnesia. Theories of retrograde amnesia have encompassed storage versus access disruption, physiological processes of 'consolidation', the progressive transformation of episodic memories into a more 'semantic' form, and multiple-trace theory. Single-case investigations, group studies and various forms of neuroimaging can all contribute to the resolution of these controversies.

Introduction to the use of regression models in epidemiology.

PubMed

Bender, Ralf

2009-01-01

Regression modeling is one of the most important statistical techniques used in analytical epidemiology. By means of regression models the effect of one or several explanatory variables (e.g., exposures, subject characteristics, risk factors) on a response variable such as mortality or cancer can be investigated. From multiple regression models, adjusted effect estimates can be obtained that take the effect of potential confounders into account. Regression methods can be applied in all epidemiologic study designs so that they represent a universal tool for data analysis in epidemiology. Different kinds of regression models have been developed in dependence on the measurement scale of the response variable and the study design. The most important methods are linear regression for continuous outcomes, logistic regression for binary outcomes, Cox regression for time-to-event data, and Poisson regression for frequencies and rates. This chapter provides a nontechnical introduction to these regression models with illustrating examples from cancer research.

Childhood adversity, mental disorder comorbidity, and suicidal behavior in schizotypal personality disorder.

PubMed

Lentz, Vanessa; Robinson, Jennifer; Bolton, James M

2010-11-01

Schizotypal personality disorder (SPD) is a serious and relatively common psychiatric disorder, yet remains understudied among the personality disorders. The current study examines the psychiatric correlates of SPD in a representative epidemiologic sample, utilizing data from the National Epidemiological Survey on Alcohol and Related Conditions (N = 34,653). Multiple logistic regression compared people with SPD to the general population across a broad range of childhood adversities, comorbid psychiatric disorders, and suicidal behavior. SPD was strongly associated with many adverse childhood experiences. After adjusting for confounding factors, SPD was independently associated with major depression and several anxiety disorders, including post-traumatic stress disorder. Interestingly, SPD was more strongly associated with borderline and narcissistic personality disorders than cluster A personality disorders. Individuals with SPD were also more likely to attempt suicide. As a whole, these results suggest that individuals with SPD experience significant morbidity and may be at increased risk of mortality.

Familial risk moderates the association between sleep and zBMI in children.

PubMed

Bagley, Erika J; El-Sheikh, Mona

2013-08-01

A cumulative risk approach was used to examine the moderating effect of familial risk factors on relations between actigraphy-based sleep quantity (minutes) and quality (efficiency) and sex- and age-standardized body mass index (zBMI). The sample included 124 boys and 104 girls with a mean age of 10.41 years (SD = 0.67). Children wore actigraphs for 1 week, and their height and weight were assessed in the lab. After controlling for potential confounds, multiple regression analyses indicated that sleep minutes predicted children's zBMI and that both sleep minutes and efficiency interacted with family risk in the prediction of zBMI. The association between poor sleep and zBMI was especially evident for children exposed to higher levels of family risk. Findings suggest that not all children who exhibit poor sleep are at equal risk for higher zBMI and that familial and contextual conditions need to be considered in this link.

The risk of adolescent suicide across patterns of drug use: a nationally representative study of high school students in the United States from 1999 to 2009.

PubMed

Wong, Shane Shucheng; Zhou, Bo; Goebert, Deborah; Hishinuma, Earl S

2013-10-01

Substance use is associated with suicidal ideation, planning and attempts among adolescents, but it is unclear how this association varies across different types and number of substances. This study examined the association between patterns of substance use and suicidality among a nationally representative sample of high school students in the United States during the last decade. Data from the 2001 to 2009 Youth Risk Behavior Survey including 73,183 high school students were analyzed. Logistic regression analyses examined the association between lifetime use of ten common substances of abuse (alcohol, cocaine, ecstasy, hallucinogens, heroin, inhalants, marijuana, methamphetamines, steroids, and tobacco) and four measures of suicidality over the last year (suicidal ideation, suicide plan, suicide attempt, and severe suicide attempt requiring medical attention), controlling for potential confounders (socio-demographic variables, interpersonal violence, sexual intercourse, and symptoms of depression and eating disorder). Among the ten substances, univariate analysis demonstrates that adolescents reporting a history of heroin use have the strongest association with suicidal ideation, suicide plan, suicide attempts and severe suicide attempts in the last year (odds ratio = 5.0, 5.9, 12.0, and 23.6 compared to non-users), followed by users of methamphetamines (OR = 4.3-13.1) and steroids (OR = 3.7-11.8). Cocaine, ecstasy, hallucinogens and inhalants had a moderate association with suicidality (OR = 3.1-10.8). Users of marijuana, alcohol and tobacco also had an increased odds ratio of suicidality (OR = 1.9-5.2). The association between each of ten substances and the four measures of suicidality remained significant with multivariate analysis controlling for multiple confounders (p < 0.05), except for the association between alcohol use and severe suicide attempts. The seven illicit substances had a stronger association with severe suicide attempts as compared to all other confounding risk factors except depression. The number of substances used had a graded relationship to suicidality. Substance abuse is a strong risk factor for suicidal thoughts and behaviors among American high school students, with the strength of this relationship dramatically increasing with particular illicit drugs and a higher number of substances. The findings reinforce the importance of routine screening for substance abuse in the assessment of adolescent suicide risk.

A prospective cohort study of disability pension due to mental diagnoses: the importance of health factors and behaviors

PubMed Central

2013-01-01

Background Previous studies have found associations between various health factors and behaviors and mental disorders. However, knowledge of such associations with disability pension (DP) due to mental diagnoses is scarce. Moreover, the influence of familial factors (genetics and family background) on the associations are mainly unknown. The aim of the study was to investigate associations between health factors and behaviors and future DP due to mental diagnoses in a twin cohort, accounting for familial confounding. Methods A prospective cohort study of Swedish twins (N=28 613), including survey data and national register data on DP and other background factors was conducted. Cox proportional hazards regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI) for the whole twin cohort, and for discordant twin pairs. Results During follow-up 1998–2008 (median 10 years), 2.2% of the cohort was granted a DP with a mental diagnosis. In the fully adjusted analyses of the whole cohort, the associations of poor or moderate self-rated health (SRH), under- or overweight, former or current tobacco use, or being an abstainer from alcohol were significantly associated with risk of DP due to mental diagnoses. Analyses of discordant twin pairs confirmed all these associations, except for current tobacco use, being independent from familial confounding. Exclusion of individuals with current or previous depression or anxiety at baseline did not influence the associations found. Conclusions Poor or moderate SRH, under- or overweight, former tobacco use or being an abstainer from alcohol seem to be strong direct predictors of DP due to mental diagnoses, independently of several confounders of this study, including familial factors. PMID:23816331

Genetic Instrumental Variable Studies of Effects of Prenatal Risk Factors

PubMed Central

von Hinke Kessler Scholder, Stephanie

2013-01-01

Identifying the effects of maternal risk factors during pregnancy on infant and child health is an area of tremendous research interest. However, of interest to policy makers is unraveling the causal effects of prenatal risk factors, not their associations with child health, which may be confounded by several unobserved factors. In this paper, we evaluate the utility of genetic variants in three genes that have unequivocal evidence of being related to three major risk factors – CHRNA3 for smoking, ADH1B for alcohol use, and FTO for obesity – as instrumental variables for identifying the causal effects of such factors during pregnancy. Using two independent datasets, we find that these variants are overall predictive of the risk factors and are not systematically related to observed confounders, suggesting that they may be useful instruments. We also find some suggestive evidence that genetic effects are stronger during than before pregnancy. We provide an empirical example illustrating the use of these genetic variants as instruments to evaluate the effects of risk factors on birth weight. Finally, we offer suggestions for researchers contemplating the use of these variants as instruments. PMID:23701534

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/

Using Observational Data to Estimate the Effect of Hand Washing and Clean Delivery Kit Use by Birth Attendants on Maternal Deaths after Home Deliveries in Rural Bangladesh, India and Nepal

PubMed Central

Seward, Nadine; Prost, Audrey; Copas, Andrew; Corbin, Marine; Li, Leah; Colbourn, Tim; Osrin, David; Neuman, Melissa; Azad, Kishwar; Kuddus, Abdul; Nair, Nirmala; Tripathy, Prasanta; Manandhar, Dharma; Costello, Anthony; Cortina-Borja, Mario

2015-01-01

Background Globally, puerperal sepsis accounts for an estimated 8–12% of maternal deaths, but evidence is lacking on the extent to which clean delivery practices could improve maternal survival. We used data from the control arms of four cluster-randomised controlled trials conducted in rural India, Bangladesh and Nepal, to examine associations between clean delivery kit use and hand washing by the birth attendant with maternal mortality among home deliveries. Methods We tested associations between clean delivery practices and maternal deaths, using a pooled dataset for 40,602 home births across sites in the three countries. Cross-sectional data were analysed by fitting logistic regression models with and without multiple imputation, and confounders were selected a priori using causal directed acyclic graphs. The robustness of estimates was investigated through sensitivity analyses. Results Hand washing was associated with a 49% reduction in the odds of maternal mortality after adjusting for confounding factors (adjusted odds ratio (AOR) 0.51, 95% CI 0.28–0.93). The sensitivity analysis testing the missing at random assumption for the multiple imputation, as well as the sensitivity analysis accounting for possible misclassification bias in the use of clean delivery practices, indicated that the association between hand washing and maternal death had been over estimated. Clean delivery kit use was not associated with a maternal death (AOR 1.26, 95% CI 0.62–2.56). Conclusions Our evidence suggests that hand washing in delivery is critical for maternal survival among home deliveries in rural South Asia, although the exact magnitude of this effect is uncertain due to inherent biases associated with observational data from low resource settings. Our findings indicating kit use does not improve maternal survival, suggests that the soap is not being used in all instances that kit use is being reported. PMID:26295838

Effects of environmental lead pollution on blood lead and sex hormone levels among occupationally exposed group in an E-waste dismantling area.

PubMed

Yang, Yan; Lu, Xiao Song; Li, Ding Long; Yu, Yun Jiang

2013-06-01

To study the effects of environmental multi-media lead pollution on blood lead and sex hormone levels among lead exposed males engaged in E-waste dismantling, and the correlation between confounding factors and sex hormone levels. An E-waste dismantling area in Taizhou of Zhejiang Province was selected as the research site. One hundred and fifty two samples were collected from the groundwater, soil, rice, corn, chicken, and pork in the dismantling area. The effects of the multi-media lead pollution on the male blood lead and sex hormone levels of FSH, LH, and T, as well as the correlation with confounding factors, were studied. The blood lead concentrations in the males aged under 31, from 31 to 45 and from 46 to 60 were 98.55, 100.23, and 101.45 μg/L, respectively. Of all the environmental media lead exposures, the groundwater, rice and soil were main contributing factors to the lead accumulation in humans. FSH and LH levels increased with the age while the T levels decreased with the age instead. There was a significant correlation between the FSH and LH levels and wearing masks. There was correlation between the FSH, LH, and T levels, and the mean values of lead concentrations in environmental media, and the sex hormone levels were correlated with the confounding factor of wearing masks. Copyright © 2013 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

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.

Impact of marital status, insurance status, income, and race/ethnicity on the survival of younger patients diagnosed with multiple myeloma in the United States.

PubMed

Costa, Luciano J; Brill, Ilene K; Brown, Elizabeth E

2016-10-15

Recent advances in the treatment of multiple myeloma (MM) have been associated with improved survival, predominantly among young and white patients. The authors hypothesized that sociodemographic factors, adjusted for race/ethnicity, influence the survival of younger patients with MM. Overall survival (OS) data were obtained for individuals included in the Surveillance, Epidemiology, and End Results (SEER-18) program who were diagnosed with MM before the age of 65 years between 2007 and 2012. The sociodemographic variables addressed were marital status, insurance status, median household income, and educational achievement in the county of residence. Race/ethnicity was defined as a self-reported construct including Hispanic (regardless of race), non-Hispanic black, non-Hispanic white, and other. There were 10,161 cases of MM included with a median follow-up of 27 months (range, 0-71 months; 22,179 person-years). Using multivariable Cox proportional hazards analysis, SEER registry; age; male sex; and 3 sociodemographic factors including marital status (other than married), insurance status (uninsured or Medicaid), and county-level income (lowest 2 quartiles), but not race/ethnicity, were found to be associated with an increased risk of death. The 4-year estimated OS rate was 71.1%, 63.2%, 53.4%, and 46.5% (P<.001), respectively, for patients with 0, 1, 2, or 3 adverse sociodemographic factors. Hispanic and non-Hispanic black individuals were found to have more adverse sociodemographic factors and worse OS. However, when the population was stratified by the cumulative number of sociodemographic factors, no consistent association between race/ethnicity and OS was observed after adjustment for confounders. Sociodemographic factors that potentially affect care, but not race/ethnicity, were found to influence the survival of younger patients with MM. Cancer 2016;122:3183-90. © 2016 American Cancer Society. © 2016 American Cancer Society.

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

A Comprehensive Analysis of the SRS-Schwab Adult Spinal Deformity Classification and Confounding Variables: A Prospective, Non-US Cross-sectional Study in 292 Patients.

PubMed

Hallager, Dennis Winge; Hansen, Lars Valentin; Dragsted, Casper Rokkjær; Peytz, Nina; Gehrchen, Martin; Dahl, Benny

2016-05-01

Cross-sectional analyses on a consecutive, prospective cohort. To evaluate the ability of the Scoliosis Research Society (SRS)-Schwab Adult Spinal Deformity Classification to group patients by widely used health-related quality-of-life (HRQOL) scores and examine possible confounding variables. The SRS-Schwab Adult Spinal Deformity Classification includes sagittal modifiers considered important for HRQOL and the clinical impact of the classification has been validated in patients from the International Spine Study Group database; however, equivocal results were reported for the Pelvic Tilt modifier and potential confounding variables were not evaluated. Between March 2013 and May 2014, all adult spinal deformity patients from our outpatient clinic with sufficient radiographs were prospectively enrolled. Analyses of HRQOL variance and post hoc analyses were performed for each SRS-Schwab modifier. Age, history of spine surgery, and aetiology of spinal deformity were considered potential confounders and their influence on the association between SRS-Schwab modifiers and aggregated Oswestry Disability Index (ODI) scores was evaluated with multivariate proportional odds regressions. P values were adjusted for multiple testing. Two hundred ninety-two of 460 eligible patients were included for analyses. The SRS-Schwab Classification significantly discriminated HRQOL scores between normal and abnormal sagittal modifier classifications. Individual grade comparisons showed equivocal results; however, Pelvic Tilt grade + versus +  + did not discriminate patients according to any HRQOL score. All modifiers showed significant proportional odds for worse aggregated ODI scores with increasing grade levels and the effects were robust to confounding. However, age group and aetiology had individual significant effects. The SRS-Schwab sagittal modifiers reliably grouped patients graded 0 versus + / +  + according to the most widely used HRQOL scores and the effects of increasing grade level on odds for worse ODI scores remained significant after adjusting for potential confounders. However, effects of age group and aetiology should not be neglected. 3.

Practical applications of the bioinformatics toolbox for narrowing quantitative trait loci.

PubMed

Burgess-Herbert, Sarah L; Cox, Allison; Tsaih, Shirng-Wern; Paigen, Beverly

2008-12-01

Dissecting the genes involved in complex traits can be confounded by multiple factors, including extensive epistatic interactions among genes, the involvement of epigenetic regulators, and the variable expressivity of traits. Although quantitative trait locus (QTL) analysis has been a powerful tool for localizing the chromosomal regions underlying complex traits, systematically identifying the causal genes remains challenging. Here, through its application to plasma levels of high-density lipoprotein cholesterol (HDL) in mice, we demonstrate a strategy for narrowing QTL that utilizes comparative genomics and bioinformatics techniques. We show how QTL detected in multiple crosses are subjected to both combined cross analysis and haplotype block analysis; how QTL from one species are mapped to the concordant regions in another species; and how genomewide scans associating haplotype groups with their phenotypes can be used to prioritize the narrowed regions. Then we illustrate how these individual methods for narrowing QTL can be systematically integrated for mouse chromosomes 12 and 15, resulting in a significantly reduced number of candidate genes, often from hundreds to <10. Finally, we give an example of how additional bioinformatics resources can be combined with experiments to determine the most likely quantitative trait genes.

A prospective study of psychosocial work characteristics and long sick leave of Japanese male employees in multiple workplaces.

PubMed

Ishizaki, Masao; Kawakami, Norito; Honda, Ryumon; Yamada, Yuichi; Nakagawa, Hideaki; Morikawa, Yuko

2013-01-01

The aim of this study was to identify psychosocial work characteristics associated with long sick leave in a large population of male Japanese employees in multiple workplaces. We examined various psychosocial work characteristics (job overload, job control, supervisor support, coworker support, support by family and friends, role ambiguity, role conflict, intragroup conflict and intergroup conflict) of employees in six factories at the base line. We then conducted a follow-up survey on the recorded long sick leaves of ≥ 30 continuous days taken by the employees due to any medical condition. We found 574 cases of long sick leave out of 15,531 subjects during an average 5.07-yr follow-up. The results showed that high supervisor support was significantly associated with a decrease in the hazard ratio (HR) of long sick leave after adjustment for several confounding factors (95%CI; 0.69-0.97). High role ambiguity also tended to increase HR, but without reaching significance (95%CI; 0.99-1.41). The results suggest that supervisor support in the workplace may be important to reduce long sick leave in Japanese male employees.

Parent figure transitions and delinquency and drug use among early adolescent children of substance abusers.

PubMed

Keller, Thomas E; Catalano, Richard F; Haggerty, Kevin P; Fleming, Charles B

2002-01-01

Children of substance abusing parents have an elevated risk for experiencing disruptions in household composition and for engaging in problem behaviors. This study investigated whether multiple parent figure transitions predicted the likelihood of delinquency and drug use among a sample of early adolescents with parents receiving methadone treatment for opiate addiction. Controlling for baseline delinquency, child characteristics, family conflict, parental depression, and parent criminal history, a greater number of parenting disruptions during the longitudinal study period was associated with a higher probability of delinquent behavior. Gender moderated the effect of parent figure transitions in a parallel analysis for drug use. After accounting for baseline drug use and potentially confounding factors, only adolescent females had a higher likelihood of drug use as the number of family disruptions increased. In contrast, age was strongly associated with drug use for males. A subgroup of youths who experienced tremendous family instability and had no single consistent parent figure during the study period were at extreme risk for delinquent behavior. The findings are interpreted in terms of cumulative stress resulting from multiple parenting disruptions over time and differential influences on the expression of problem behaviors depending on gender.

Analyzing the association between fish consumption and osteoporosis in a sample of Chinese men.

PubMed

Li, Xia; Lei, Tao; Tang, Zihui; Dong, Jingcheng

2017-04-19

The main purpose of this study was to estimate the associations between frequency of fish food consumption and osteoporosis (OP) in general Chinese men. We conducted a large-scale, community-based, cross-sectional study to investigate the associations by using self-report questionnaire to access frequency of fish food intake. A total of 1092 men were available for data analysis in this study. Multiple regression models controlling for confounding factors to include frequency of fish food consumption variable were performed to investigate the relationships for OP. Positive correlations between frequency of fish food consumption and T score were reported (β = 0.084, P value = 0.025). Multiple regression analysis indicated that the frequency of fish food consumption was significantly associated with OP (P < 0.05 for model 1 and model 2). The men with high frequency of fish food consumption had a lower prevalence of OP. The findings indicated that frequency of fish food consumption was independently and significantly associated with OP. The prevalence of OP was less frequent in Chinese men preferring fish food habits. ClinicalTrials.gov Identifier: NCT02451397 retrospectively registered 28 May 2015.

Not only body weight perception but also body mass index is relevant to suicidal ideation and self-harming behavior in Japanese adolescents.

PubMed

Kinoshita, Kuni; Kinoshita, Yoshihiro; Shimodera, Shinji; Nishida, Atsushi; Inoue, Ken; Watanabe, Norio; Oshima, Norihito; Akechi, Tatsuo; Sasaki, Tsukasa; Inoue, Shimpei; Furukawa, Toshiaki A; Okazaki, Yuji

2012-04-01

Whether a low body mass index (BMI) is directly associated with a high risk of suicidal ideation or self-harming behavior in adolescents is still inconclusive. This study has, therefore, evaluated the relevance of BMI to suicidal ideation and self-harming behavior after controlling for body weight perception (BWP) and other potential confounding factors. BMI, BWP, suicidal ideation, and self-harming behavior were all assessed using a self-report questionnaire administered to 18,104 Japanese adolescents. Potential confounding factors were also evaluated. The data were then analyzed using bivariate and multivariate logistic regression. Low BMI was associated with suicidal ideation and deliberate self-harm when controlling for sex, age, drug use, emotional distress, and BWP. Low BMI may be an independent risk factor for suicidal ideation and deliberate self-harming behavior in Japanese adolescents.

Maternal obesity and childhood wheezing and asthma.

PubMed

Rusconi, Franca; Popovic, Maja

2017-03-01

Obesity represents one of the major public health problems worldwide, with an increased prevalence also among women of reproductive age. Maternal pre-pregnancy overweight and obesity are important risk factors for a number of maternal and foetal/neonatal complications. The objective of this review is to provide an overview of the most recent evidence regarding the associations between pre-pregnancy overweight/obesity and wheezing and asthma in childhood. Potential mechanisms, mediators and confounding factors involved in these associations are also discussed. Despite the relatively large body of studies examining these associations and taking into account main confounders and potential mediators, the causal relationship between maternal obesity and wheezing and asthma in childhood is still uncertain. This uncertainty is not trivial, as any prevention strategy aimed at reducing the burden of these conditions would necessarily imply better understanding of the factors that are in the causal chain. Copyright © 2016. Published by Elsevier Ltd.

Factors Influencing Observed Tillage Impacts on Herbicide Transport

USDA-ARS?s Scientific Manuscript database

The widespread use and potential human health effects of the herbicides atrazine and glyphosate have generated interest in establishing how no-tillage impacts loading of these herbicides to runoff water in comparison to other tillage practices. In this study, potentially confounding factors such as ...

Intrauterine growth retardation (IUGR): epidemiology and etiology.

PubMed

Romo, Agustín; Carceller, Raquel; Tobajas, Javier

2009-02-01

Intrauterine growth retardation (IUGR) is mainly due to a pathologic slow-down in the fetal growth pace, resulting in a fetus that is unable to reach its growth potential. IUGR frequency will vary depending on the discrimination criteria adopted. It is extremely important to use local or national fetal growth graphs in order to avoid some confounding factors. IUGR incidence in newborns would be between 3% and 7% of the total population. In our experience it is 5.13% a figure similar to the one obtained by other authors but with a progressively higher incidence during the last decade. There are multiple maternal factors that can generally be grouped into constitutional and general factors given that they affect age, weight, race, maternal cardiac volume, etc, socioeconomic factors with key incidence in the mother's nutrition level, where a poor maternal nutrition level would be the key factor in this group. We have evaluated multiple factors as possible contributors to the IUGR risk: race, parents' age, mother's height (cm), mother's birth weight and before pregnancy (kg), ponderal gain and blood pressure during pregnancy, and previous SGA newborns. Socioeconomic factors like social class, parents' profession, habitual residence, salary, immigration, and diet were also evaluated. We also included variables such as total daily working time and time mothers spent standing up, daily sleeping time (hrs), stress self-perception test at work and primiparity age. Toxic factors during pregnancy: tobacco (active and passive), alcohol, drugs and coffee consumption. Fetal or utero-placental factors were considered. In our study, the most significant etiologic factors were: Active and passive tobacco consuming, mother's stress level, increase of total months worked during pregnancy, total daily working hours and time mothers spent standing up and finally, the parent's height. Our data support the main objective of reducing the incidence of SGA newborns after IUGR by fighting against tobacco from all fields, including the passive smoking habit, and improving the laboral conditions of the pregnant mother, lowering the number of daily hours worked, the physical activity and trying to avoid and to cope with stressful situations.

The Relation between Binge Drinking and Academic Performance: Considering the Mediating Effects of Academic Involvement

ERIC Educational Resources Information Center

An, Brian P.; Loes, Chad N.; Trolian, Teniell L.

2017-01-01

Using longitudinal data from multiple institutions, we focused on the relation between binge drinking and academic performance. Binge drinking exerts a negative influence on grade point average, even after accounting for a host of precollege confounding variables. Furthermore, the number of times a student binge drinks in college is less…

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.

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.

On Estimation of the Survivor Average Causal Effect in Observational Studies when Important Confounders are Missing Due to Death

PubMed Central

Egleston, Brian L.; Scharfstein, Daniel O.; MacKenzie, Ellen

2008-01-01

We focus on estimation of the causal effect of treatment on the functional status of individuals at a fixed point in time t* after they have experienced a catastrophic event, from observational data with the following features: (1) treatment is imposed shortly after the event and is non-randomized, (2) individuals who survive to t* are scheduled to be interviewed, (3) there is interview non-response, (4) individuals who die prior to t* are missing information on pre-event confounders, (5) medical records are abstracted on all individuals to obtain information on post-event, pre-treatment confounding factors. To address the issue of survivor bias, we seek to estimate the survivor average causal effect (SACE), the effect of treatment on functional status among the cohort of individuals who would survive to t* regardless of whether or not assigned to treatment. To estimate this effect from observational data, we need to impose untestable assumptions, which depend on the collection of all confounding factors. Since pre-event information is missing on those who die prior to t*, it is unlikely that these data are missing at random (MAR). We introduce a sensitivity analysis methodology to evaluate the robustness of SACE inferences to deviations from the MAR assumption. We apply our methodology to the evaluation of the effect of trauma center care on vitality outcomes using data from the National Study on Costs and Outcomes of Trauma Care. PMID:18759833

Non-allergic cutaneous reactions in airborne chemical sensitivity--a population based study.

PubMed

Berg, Nikolaj Drimer; Linneberg, Allan; Thyssen, Jacob Pontoppidan; Dirksen, Asger; Elberling, Jesper

2011-06-01

Multiple chemical sensitivity (MCS) is characterised by adverse effects due to exposure to low levels of chemical substances. The aetiology is unknown, but chemical related respiratory symptoms have been found associated with positive patch test. The purpose of this study was to investigate the relationship between cutaneous reactions from patch testing and self-reported severity of chemical sensitivity to common airborne chemicals. A total of 3460 individuals participating in a general health examination, Health 2006, were patch tested with allergens from the European standard series and screened for chemical sensitivity with a standardised questionnaire dividing the participants into four severity groups of chemical sensitivity. Both allergic and non-allergic cutaneous reactions--defined as irritative, follicular, or doubtful allergic reactions--were analysed in relationship with severity of chemical sensitivity. Associations were controlled for the possible confounding effects of sex, age, asthma, eczema, atopic dermatitis, psychological and social factors, and smoking habits. In unadjusted analyses we found associations between allergic and non-allergic cutaneous reactions on patch testing and the two most severe groups of self-reported sensitivity to airborne chemicals. When adjusting for confounding, associations were weakened, and only non-allergic cutaneous reactions were significantly associated with individuals most severely affected by inhalation of airborne chemicals (odds ratio = 2.5, p = 0.006). Our results suggest that individuals with self-reported chemical sensitivity show increased non-allergic cutaneous reactions based on day 2 readings of patch tests. Copyright © 2011 Elsevier GmbH. All rights reserved.

Association between zolpidem use and glaucoma risk: a Taiwanese population-based case-control study.

PubMed

Ho, Yi-Hao; Chang, Yue-Cune; Huang, Wei-Cheng; Chen, Hsin-Yi; Lin, Che-Chen; Sung, Fung-Chang

2015-01-01

To date, the relationship between zolpidem use and subsequent risk of glaucoma in a Taiwanese population has not been assessed. We used data from the National Health Insurance system to investigate whether zolpidem use was related to glaucoma risk. A 1:4 matched case-control study was conducted. The cases were patients newly diagnosed with glaucoma from 2001 to 2010. The controls were randomly selected non-glaucoma subjects matched by sex and age (± 5 years). Zolpidem exposure and/or the average dosage of zolpidem used (mg/year) were evaluated. Medical comorbidities were considered as confounding factors. Multiple logistic regression models were used to evaluate the potential risk of zolpidem exposure on glaucoma with/without adjustment for the effects of confounding variables. The exposure rate of zolpidem use in the glaucoma group was significantly higher than that of the control group (2.8% vs. 2.0%, P < 0.0001). The adjusted odds ratio (OR) of the risk of glaucoma for those with zolpidem use vs. those without was 1.19 (95% confidence interval [CI], 1.02-1.38). Compared to non-zolpidem users, zolpidem users with an average dose of more than 200 mg/year had significantly increased risk of glaucoma (OR 1.31, 95% CI 1.03-1.68). This study suggests that the use of zolpidem might increase the risk of subsequent glaucoma. Further confirmatory studies are recommended to clarify this important issue.

Association Between Zolpidem Use and Glaucoma Risk: A Taiwanese Population-Based Case-Control Study

PubMed Central

Ho, Yi-Hao; Chang, Yue-Cune; Huang, Wei-Cheng; Chen, Hsin-Yi; Lin, Che-Chen; Sung, Fung-Chang

2015-01-01

Background To date, the relationship between zolpidem use and subsequent risk of glaucoma in a Taiwanese population has not been assessed. Methods We used data from the National Health Insurance system to investigate whether zolpidem use was related to glaucoma risk. A 1:4 matched case-control study was conducted. The cases were patients newly diagnosed with glaucoma from 2001 to 2010. The controls were randomly selected non-glaucoma subjects matched by sex and age (±5 years). Zolpidem exposure and/or the average dosage of zolpidem used (mg/year) were evaluated. Medical comorbidities were considered as confounding factors. Multiple logistic regression models were used to evaluate the potential risk of zolpidem exposure on glaucoma with/without adjustment for the effects of confounding variables. Results The exposure rate of zolpidem use in the glaucoma group was significantly higher than that of the control group (2.8% vs. 2.0%, P < 0.0001). The adjusted odds ratio (OR) of the risk of glaucoma for those with zolpidem use vs. those without was 1.19 (95% confidence interval [CI], 1.02–1.38). Compared to non-zolpidem users, zolpidem users with an average dose of more than 200 mg/year had significantly increased risk of glaucoma (OR 1.31, 95% CI 1.03–1.68). Conclusions This study suggests that the use of zolpidem might increase the risk of subsequent glaucoma. Further confirmatory studies are recommended to clarify this important issue. PMID:25720944

Association Between Zolpidem Use and Glaucoma Risk: A Taiwanese Population-Based Case-Control Study.

PubMed

Ho, Yi-Hao; Chang, Yue-Cune; Huang, Wei-Cheng; Chen, Hsin-Yi; Lin, Che-Chen; Sung, Fung-Chang

2014-08-23

Background: To date, the relationship between zolpidem use and subsequent risk of glaucoma in a Taiwanese population has not been assessed.Methods: We used data from the National Health Insurance system to investigate whether zolpidem use was related to glaucoma risk. A 1:4 matched case-control study was conducted. The cases were patients newly diagnosed with glaucoma from 2001 to 2010. The controls were randomly selected non-glaucoma subjects matched by sex and age (±5 years). Zolpidem exposure and/or the average dosage of zolpidem used (mg/year) were evaluated. Medical comorbidities were considered as confounding factors. Multiple logistic regression models were used to evaluate the potential risk of zolpidem exposure on glaucoma with/without adjustment for the effects of confounding variables.Results: The exposure rate of zolpidem use in the glaucoma group was significantly higher than that of the control group (2.8% vs. 2.0%, P < 0.0001). The adjusted odds ratio (OR) of the risk of glaucoma for those with zolpidem use vs. those without was 1.19 (95% confidence interval [CI], 1.02-1.38). Compared to non-zolpidem users, zolpidem users with an average dose of more than 200 mg/year had significantly increased risk of glaucoma (OR 1.31, 95% CI 1.03-1.68).Conclusions: This study suggests that the use of zolpidem might increase the risk of subsequent glaucoma. Further confirmatory studies are recommended to clarify this important issue.

The confounding effects of hybridization on phylogenetic estimation in the New Zealand cicada genus Kikihia.

PubMed

Banker, Sarah E; Wade, Elizabeth J; Simon, Chris

2017-11-01

Phylogenetic studies of multiple independently inherited nuclear genes considered in combination with patterns of inheritance of organelle DNA have provided considerable insight into the history of species evolution. In particular, investigations of cicadas in the New Zealand genus Kikihia have identified interesting cases where mitochondrial DNA (mtDNA) crosses species boundaries in some species pairs but not others. Previous phylogenetic studies focusing on mtDNA largely corroborated Kikihia species groups identified by song, morphology and ecology with the exception of a unique South Island mitochondrial haplotype clade-the Westlandica group. This newly identified group consists of diverse taxa previously classified as belonging to three different sub-generic clades. We sequenced five nuclear loci from multiple individuals from every species of Kikihia to assess the nuclear gene concordance for this newly-identified mtDNA lineage. Bayes Factor analysis of the constrained phylogeny suggests some support for the mtDNA-based hypotheses, despite the fact that neither concatenation nor multiple species tree methods resolve the Westlandica group as monophyletic. The nuclear analyses suggest a geographic distinction between clearly defined monophyletic North Island clades and unresolved South Island clades. We suggest that more extreme habitat modification on South Island during the Pliocene and Pleistocene resulted in secondary contact and hybridization between species pairs and a series of mitochondrial capture events followed by subsequent lineage evolution. Copyright © 2017 Elsevier Inc. All rights reserved.

Substance use in adulthood following adolescent self-harm: a population-based cohort study

PubMed Central

Moran, P; Coffey, C; Romaniuk, H; Degenhardt, L; Borschmann, R; Patton, G C

2015-01-01

Objective To determine whether adolescents who self-harm are at increased risk of heavy and dependent substance use in adulthood. Method Fifteen-year prospective cohort study of a random sample of 1943 adolescents recruited from secondary schools across the state of Victoria, Australia. Data pertaining to self-harm and substance use was obtained at seven waves of follow-up, from mean age 15.9 years to mean age 29.1 years. Results Substance use and self-harm were strongly associated during the adolescent years (odds ratio (OR): 3.3, 95% CI 2.1–5.0). Moreover, adolescent self-harmers were at increased risk of substance use and dependence syndromes in young adulthood. Self-harm predicted a four-fold increase in the odds of multiple dependence syndromes (sex- and wave-adjusted OR: 4.2, 95% CI: 2.7–6.6). Adjustment for adolescent anxiety/depression attenuated but did not eliminate most associations. Adolescent substance use confounded all associations, with the exception of multiple dependence syndromes, which remained robustly associated with adolescent self-harm (fully adjusted odds ratio: 2.0, 95% CI: 1.2–3.2). Conclusion Adolescent self-harm is an independent risk factor for multiple dependence syndromes in adulthood. This level of substance misuse is likely to contribute substantially to the premature mortality and disease burden experienced by individuals who self-harm. PMID:24954250

Musculoskeletal pain and re-employment among unemployed job seekers: a three-year follow-up study.

PubMed

Nwaru, Chioma A; Nygård, Clas-Håkan; Virtanen, Pekka

2016-07-08

Poor health is a potential risk factor for not finding employment among unemployed individuals. We investigated the associations between localized and multiple-site musculoskeletal pain and re-employment in a three-year follow-up of unemployed job seekers. Unemployed people (n = 539) from six localities in southern Finland who participated in various active labour market policy measures at baseline in 2002/2003 were recruited into a three-year health service intervention trial. A questionnaire was used to collect data on musculoskeletal health and background characteristics at baseline and on employment status at the end of the follow-up. We conducted a complete case (n = 284) and multiple imputation analyses using logistic regression to investigate the association between baseline musculoskeletal pain and re-employment after three years. Participants with severe pain in the lower back were less likely to become re-employed. This was independent of potential confounding variables. Pain in the hands/upper extremities, neck/shoulders, lower extremities, as well as multiple site were not determinants of re-employment. Our findings lend some support to the hypothesis that poor health can potentially cause health selection into employment. There is the need to disentangle health problems in order to clearly appreciate their putative impact on employment. This will allow for more targeted interventions for the unemployed.

Iterative Usage of Fixed and Random Effect Models for Powerful and Efficient Genome-Wide Association Studies

PubMed Central

Liu, Xiaolei; Huang, Meng; Fan, Bin; Buckler, Edward S.; Zhang, Zhiwu

2016-01-01

False positives in a Genome-Wide Association Study (GWAS) can be effectively controlled by a fixed effect and random effect Mixed Linear Model (MLM) that incorporates population structure and kinship among individuals to adjust association tests on markers; however, the adjustment also compromises true positives. The modified MLM method, Multiple Loci Linear Mixed Model (MLMM), incorporates multiple markers simultaneously as covariates in a stepwise MLM to partially remove the confounding between testing markers and kinship. To completely eliminate the confounding, we divided MLMM into two parts: Fixed Effect Model (FEM) and a Random Effect Model (REM) and use them iteratively. FEM contains testing markers, one at a time, and multiple associated markers as covariates to control false positives. To avoid model over-fitting problem in FEM, the associated markers are estimated in REM by using them to define kinship. The P values of testing markers and the associated markers are unified at each iteration. We named the new method as Fixed and random model Circulating Probability Unification (FarmCPU). Both real and simulated data analyses demonstrated that FarmCPU improves statistical power compared to current methods. Additional benefits include an efficient computing time that is linear to both number of individuals and number of markers. Now, a dataset with half million individuals and half million markers can be analyzed within three days. PMID:26828793

Is familial risk for depression confounded by individual and familial socioeconomic factors and neighborhood environmental factors? A 7-year follow-up study in Sweden.

PubMed

Hamano, Tsuyoshi; Li, Xinjun; Lönn, Sara Larsson; Nabika, Toru; Sundquist, Jan; Sundquist, Kristina

2018-05-16

Family history of depression is an important risk factor for depression. The aim of this study was to examine whether the effect of family history of depression is confounded by individual and familial socioeconomic factors (i.e., country of origin, educational attainment, family income and mobility) and neighborhood environmental factors (i.e., neighborhood deprivation and neighborhood social capital). The study population comprised 188,907 individuals aged 20-44 years from a nationwide sample of primary care centers in Sweden. Among these individuals, 22,014 with a first event of depression (6,486 men and 15,528 women) were identified during the 7-year follow-up period. Family history of depression was defined as depression in at least one parent. Cross-classified multilevel logistic regression models were used to calculate odds ratios with 95% credible intervals. Increased familial odds were observed after adjustment for individual and familial socioeconomic factors and neighborhood environmental factors for both men and women. Our results suggest that family history of depression is an independent risk factor for depression. Offspring of parents with depression are important targets for disease prevention, regardless of individual and familial socioeconomic factors and neighborhood environmental factors. Copyright © 2018. Published by Elsevier B.V.

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.

Sick-building symptoms in office workers in northeastern France: a pilot study.

PubMed

Teculescu, D B; Sauleau, E A; Massin, N; Bohadana, A B; Buhler, O; Benamghar, L; Mur, J M

1998-07-01

To verify that sick building symptoms are present in north-eastern France office workers; to try to identify new confounding factors. The design was that of a cross-sectional study with control group. We studied with the same methods the personnel of an air-conditioned building (n=425), and of a naturally ventilated building (n=351). Air temperature and humidity, bacterial and fungal densities were measured by the same technical staff in the two buildings. A standard questionnaire on irritative and respiratory symptoms, personal and family history, and lifestyle was completed by the participants. In univariate analysis, exposure to air-conditioning was associated with an increased prevalence of symptoms (odds ratios-OR-between 1.54 and 2.84). A significant increase in sickness absence was also found among subjects working in air-conditioned offices. As a series of factors were suspected to interfere with these associations, logistic regression was applied. This method confirmed exposure to be an independent determinant of 7 symptoms, and also identified two determinants not previously described: a family history of respiratory diseases and "do-it-yourself' activities. we found the sick building symptoms to be present in a group of French office workers exposed to air-conditioning. We confirmed the influence of a number of confounding factors and described two further confounders - do-it-yourself activities at home and a history of familial respiratory disease.

More Precise Estimation of Lower-Level Interaction Effects in Multilevel Models.

PubMed

Loeys, Tom; Josephy, Haeike; Dewitte, Marieke

2018-01-01

In hierarchical data, the effect of a lower-level predictor on a lower-level outcome may often be confounded by an (un)measured upper-level factor. When such confounding is left unaddressed, the effect of the lower-level predictor is estimated with bias. Separating this effect into a within- and between-component removes such bias in a linear random intercept model under a specific set of assumptions for the confounder. When the effect of the lower-level predictor is additionally moderated by another lower-level predictor, an interaction between both lower-level predictors is included into the model. To address unmeasured upper-level confounding, this interaction term ought to be decomposed into a within- and between-component as well. This can be achieved by first multiplying both predictors and centering that product term next, or vice versa. We show that while both approaches, on average, yield the same estimates of the interaction effect in linear models, the former decomposition is much more precise and robust against misspecification of the effects of cross-level and upper-level terms, compared to the latter.

Anticholinergic load negatively correlates with recovery of cognitive activities of daily living for geriatric patients after stroke in the convalescent stage.

PubMed

Kose, E; Hirai, T; Seki, T; Hidaka, S; Hamamoto, T

2018-05-16

Anticholinergic drugs are associated with risks of falls, confusion and cognitive dysfunction. However, the effect of anticholinergic drug use on rehabilitation outcomes after a stroke is poorly documented. We therefore aimed to establish whether the anticholinergic load was associated with functional recovery among geriatric patients convalescing after stroke. Consecutive geriatric stroke patients admitted and discharged from a convalescence rehabilitation ward between 2010 and 2016 were included in this retrospective cohort study. Anticholinergic load was assessed by the Anticholinergic Risk Scale (ARS), and functional recovery was assessed by the Functional Independence Measure (FIM). The primary outcome was cognitive FIM (FIM-C) gain, but we also assessed the interaction of other putative factors identified from univariate analysis. Multivariate analyses were performed, adjusting for confounding factors. We included 418 participants (171 males, 247 females) with a median age of 78 years (interquartile range, 72-84 years). Multiple regression analysis revealed that ARS change, length of stay, and epilepsy were independently and negatively correlated with cognitive FIM gain. Multiple logistic regression analysis indicated that the "Comprehension" and "Memory" items of the cognitive FIM gain were independently and negatively associated with anticholinergic load. A causal relationship cannot be established, but increased ARS scores during hospitalization may predict limited cognitive functional improvement in geriatric patients after stroke. Alternatively, cognitive impairment may lead to increased use of anticholinergic drugs. © 2018 John Wiley & Sons Ltd.

For patients with terminal chronic illness, does more face-to-face time with a healthcare provider decrease aggressive end-of-life (EOL) care such as ICU admission, feeding tube placement, CPR, or intubation?

PubMed Central

Seaberg, Preston; Hamm, Robert M.; McCarthy, Laine H.

2016-01-01

Clinical Question For patients with terminal chronic illness, does more face-to-face time with a healthcare provider decrease aggressive end-of-life (EOL) care such as ICU admission, feeding tube placement, CPR, or intubation? Answer Inconclusive. Existing evidence does not provide a conclusive answer to this particular question. While multiple prospective, randomized, controlled trials demonstrate an association between increased patient-provider contact time and decreased aggressive EOL care, interventions in those studies contain multiple confounding elements that preclude isolation of the time factor from the other elements in the interventions. There is a need for research focusing on physician-patient communication time and EOL care. Level of Evidence for the Answer A Search Terms Terminal care, palliative care, terminal illness, communication, patient-provider relations, time factors, life support care, resuscitation orders, enteral nutrition Inclusion Criteria Systematic reviews, meta-analyses, and comparative studies published between 2008 and the current date comparing EOL care or EOL care preferences of patients who spend more face-to-face time with a healthcare provider to those of patients who spend less face-to-face time with a healthcare provider. Exclusion Criteria Studies that do not report the primary outcome of interest (EOL care or EOL care preferences) or that do not measure discussion time or provide interventions that include face-to-face discussion. PMID:25796765

Testing for gene-environment interaction under exposure misspecification.

PubMed

Sun, Ryan; Carroll, Raymond J; Christiani, David C; Lin, Xihong

2017-11-09

Complex interplay between genetic and environmental factors characterizes the etiology of many diseases. Modeling gene-environment (GxE) interactions is often challenged by the unknown functional form of the environment term in the true data-generating mechanism. We study the impact of misspecification of the environmental exposure effect on inference for the GxE interaction term in linear and logistic regression models. We first examine the asymptotic bias of the GxE interaction regression coefficient, allowing for confounders as well as arbitrary misspecification of the exposure and confounder effects. For linear regression, we show that under gene-environment independence and some confounder-dependent conditions, when the environment effect is misspecified, the regression coefficient of the GxE interaction can be unbiased. However, inference on the GxE interaction is still often incorrect. In logistic regression, we show that the regression coefficient is generally biased if the genetic factor is associated with the outcome directly or indirectly. Further, we show that the standard robust sandwich variance estimator for the GxE interaction does not perform well in practical GxE studies, and we provide an alternative testing procedure that has better finite sample properties. © 2017, The International Biometric Society.

Birth weight and mortality: causality or confounding?

PubMed

Basso, Olga; Wilcox, Allen J; Weinberg, Clarice R

2006-08-15

The association between birth weight and mortality is among the strongest seen in epidemiology. While preterm delivery causes both small babies and high mortality, it does not explain this association. Fetal growth restriction has also been proposed, although its features are unclear because it lacks a definition independent of weight. If, as some postulate, birth weight is not itself on the causal path to mortality, its relation with mortality would have to be explained by confounding factors that decrease birth weight and increase mortality. In this paper, the authors explore the characteristics such confounders would require in order to achieve the observed association between birth weight and mortality. Through a simple simulation, they found that the observed steep gradient of risk for small babies at term can be produced by a rare condition or conditions (with a total prevalence of 0.5%) having profound effects on both fetal growth (-1.7 standard deviations) and mortality (relative risk = 160). Candidate conditions might include malformations, fetal or placental aneuploidy, infections, or imprinting disorders. If such rare factors underlie the association of birth weight with mortality, it would have broad implications for the study of fetal growth restriction and birth weight, and for the prevention of infant mortality.

A Genetically Informed Study of Associations between Family Functioning and Child Psychosocial Adjustment

ERIC Educational Resources Information Center

Schermerhorn, Alice C.; D'Onofrio, Brian M.; Turkheimer, Eric; Ganiban, Jody M.; Spotts, Erica L.; Lichtenstein, Paul; Reiss, David; Neiderhiser, Jenae M.

2011-01-01

Research has documented associations between family functioning and offspring psychosocial adjustment, but questions remain regarding whether these associations are partly due to confounding genetic factors and other environmental factors. The current study used a genetically informed approach, the Children of Twins design, to explore the…

A Genetically Informed Study of the Processes Underlying the Association Between Parental Marital Instability and Offspring Adjustment

PubMed Central

D’Onofrio, Brian M.; Turkheimer, Eric; Emery, Robert E.; Heath, Andrew C.; Madden, Pamela A.; Slutske, Wendy S.; Martin, Nicholas G.

2010-01-01

Parental divorce is associated with problematic offspring adjustment, but the relation may be due to shared genetic or environmental factors. One way to test for these confounds is to study offspring of twins discordant for divorce. The current analyses used this design to separate the mechanisms responsible for the association between parental divorce, experienced either before or after the age of 16, and offspring well-being. The results were consistent with a causal role of divorce in earlier initiation of sexual intercourse and emotional difficulties, in addition to a greater probability of educational problems, depressed mood, and suicidal ideation. In contrast, the increased risk for cohabitation and earlier initiation of drug use was explained by selection factors, including genetic confounds. PMID:16756440

Acute antepartum pyelonephritis in pregnancy: a critical analysis of risk factors and outcomes.

PubMed

Farkash, Evelina; Weintraub, Adi Y; Sergienko, Ruslan; Wiznitzer, Arnon; Zlotnik, Alex; Sheiner, Eyal

2012-05-01

To test the incidence and sonographic parameters of pyelonephritis during pregnancy, and to examine risk factors and pregnancy outcomes of women with acute antepartum pyelonephritis. A retrospective population-based study comparing all singleton pregnancies of patients with and without acute antepartum pyelonephritis was performed. Patients lacking prenatal care as well as multiple gestations were excluded from the study. Multiple logistic regression models were used to control for confounders. Out of 219,612 singleton deliveries in 1988-2010, 165 women (0.07%) suffered from acute antepartum pyelonephritis. Abnormal sonographic findings were found in 85.7% of the patients with pyelonephritis. Pyelonephritis was significantly associated with nulliparity (46.1% vs. 24.4%, p<0.001), younger maternal age (26.3 ± 6.0 vs. 28.6 ± 5.8 years, p<0.001), intrauterine growth restriction (IUGR) (6.7% vs. 2.1%, p<0.001), placental abruption (3.6% vs. 0.7%, p<0.001), low 1 min Apgar scores (10.3% vs. 6.0%, p<0.05), urinary tract infection (UTI) (4.2% vs. 0.4%, p<0.001) and preterm delivery (less than 37 weeks gestation; 20.0% vs. 7.8%; p<0.001). Using a multivariable analysis, independent risk factors for acute antepartum pyelonephritis were nulliparity (OR 2.0; 95% C.I 1.4-2.9; p<0.001), UTI (OR 10.3; 95% C.I 4.8-22.1; p<0.001) and younger maternal age (OR 0.96; 95% C.I 0.93-0.99; p=0.009). Using another multivariable analysis, with preterm delivery as the outcome variable, acute antepartum pyelonephritis was found as an independent risk factor for preterm delivery (OR 2.6; 95% C.I 1.7-3.9; p<0.001). Acute antepartum pyelonephritis is associated with adverse perinatal outcomes and specifically is an independent risk factor for preterm delivery. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Determinant of factors associated with child health outcomes and service utilization in Ghana: multiple indicator cluster survey conducted in 2011.

PubMed

Dwumoh, Duah; Essuman, Edward Eyipe; Afagbedzi, Seth Kwaku

2014-01-01

The effects of National Health Insurance Scheme in Ghana and its impact on child health outcome and service utilization cannot be underestimated. Despite the tremendous improvement in child health care in Ghana, there are still some challenges in relation to how National health insurance membership, socioeconomic status and other demographic factors impacts on child health outcomes. The study seeks to determine the association between NHIS membership, socio-economic status, geographic location and other relevant background factors, on child health service utilization and outcomes. Secondary data from the Multiple Indicator Cluster Survey conducted in 2011 was used. Multivariate analysis based on Binary Logistic Regression Models and Multiple linear regression techniques was applied to determine factors associated with child health outcomes and service utilization. Collection of best models was based on Hosmer-Lemeshow Goodness-Of-Fit as one criterion of fit and the Akaike Information Criterion. Controlling for confounding effect of socioeconomic status, age of the child, mothers education level and geographic location, the odds of a child developing anemia for children with National Health Insurance Scheme Membership is 65.2% [95% CI: 52.9-80.2] times less than children without National Health Insurance Scheme Membership. The odds of being fully immunized against common childhood illnesses for children with NHIS membership is 2.3[95% CI: 1.4-3.7] times higher than children without National Health Insurance Scheme Membership. There was no association between National Health Insurance Scheme Membership and stunted growth in children. National Health Insurance Scheme Membership was found to be related to child health service utilization (full immunization) of children under five a child's anemia status. Children with NHIS are more likely to be fully immunized against common childhood diseases and are less likely to develop anemia. Stunted growth of children was not associated with National Health Insurance Scheme Membership. Health Education on the registration and the use of the National Health Insurance should be made a national priority to enable the Ministry of Health achieve routine Immunization targets and to reduce to the bearers minimum prevalence of anemia.

Embedded Diagnostic/Prognostic Reasoning and Information Continuity for Improved Avionics Maintenance

DTIC Science & Technology

2006-01-01

enabling technologies such as built-in-test, advanced health monitoring algorithms, reliability and component aging models, prognostics methods, and...deployment and acceptance. This framework and vision is consistent with the onboard PHM ( Prognostic and Health Management) as well as advanced... monitored . In addition to the prognostic forecasting capabilities provided by monitoring system power, multiple confounding errors by electronic

Unidimensional IRT Item Parameter Estimates across Equivalent Test Forms with Confounding Specifications within Dimensions

ERIC Educational Resources Information Center

Matlock, Ki Lynn; Turner, Ronna

2016-01-01

When constructing multiple test forms, the number of items and the total test difficulty are often equivalent. Not all test developers match the number of items and/or average item difficulty within subcontent areas. In this simulation study, six test forms were constructed having an equal number of items and average item difficulty overall.…

[Effect of social desirability on dietary intake estimated from a food questionnaire].

PubMed

Barros, Renata; Moreira, Pedro; Oliveira, Bruno

2005-01-01

Self-report of dietary intake could be biased by social thus affecting risk estimates in epidemiological studies. The objective of study was to assess the effect of social desirability on dietary intake from a food frequency questionnaire (FFQ). A convenience sample of 483 Portuguese university students was recruited. Subjects were invited to complete a two-part self-administered questionnaire: the first part included the Marlowe-Crowne Social Desirability Scale (M-CSDS), a physical activity questionnaire and self-reported height and weight; the second part, included a semi-quantitative FFQ validated for Portuguese adults, that should be returned after fulfillment. All subjects completed the first part of the questionnaire and 40.4% returned the FFQ fairly completed. In multiple regression analysis, after adjustment for energy and confounders, social desirability produced a significant positive effect in the estimates of dietary fibre, vitamin C, vitamin E, magnesium and potassium, in both genders. In multiple regression, after adjustment for energy and confounders, social desirability had a significant positive effect in the estimates of vegetable consumption, for both genders, and a negative effect in white bread and beer, for women. Social desirability affected nutritional and food intake estimated from a food frequency questionnaire.

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

A propensity score approach to correction for bias due to population stratification using genetic and non-genetic factors.

PubMed

Zhao, Huaqing; Rebbeck, Timothy R; Mitra, Nandita

2009-12-01

Confounding due to population stratification (PS) arises when differences in both allele and disease frequencies exist in a population of mixed racial/ethnic subpopulations. Genomic control, structured association, principal components analysis (PCA), and multidimensional scaling (MDS) approaches have been proposed to address this bias using genetic markers. However, confounding due to PS can also be due to non-genetic factors. Propensity scores are widely used to address confounding in observational studies but have not been adapted to deal with PS in genetic association studies. We propose a genomic propensity score (GPS) approach to correct for bias due to PS that considers both genetic and non-genetic factors. We compare the GPS method with PCA and MDS using simulation studies. Our results show that GPS can adequately adjust and consistently correct for bias due to PS. Under no/mild, moderate, and severe PS, GPS yielded estimated with bias close to 0 (mean=-0.0044, standard error=0.0087). Under moderate or severe PS, the GPS method consistently outperforms the PCA method in terms of bias, coverage probability (CP), and type I error. Under moderate PS, the GPS method consistently outperforms the MDS method in terms of CP. PCA maintains relatively high power compared to both MDS and GPS methods under the simulated situations. GPS and MDS are comparable in terms of statistical properties such as bias, type I error, and power. The GPS method provides a novel and robust tool for obtaining less-biased estimates of genetic associations that can consider both genetic and non-genetic factors. 2009 Wiley-Liss, Inc.

Depression and Physical Inactivity as Confounding the Effect of Obesity on Atrial Fibrillation.

PubMed

Garimella, Roja S; Sears, Samuel F; Gehi, Anil K

2016-06-01

Obesity is associated with an increased likelihood for the development of atrial fibrillation (AF) and with worsened AF symptom severity. However, other factors that are correlated with obesity may confound or mediate the relation of obesity with AF symptom severity. The purpose of this study was to determine if depression and physical inactivity may confound the association of obesity and AF symptom severity. Health status and demographic data were captured by questionnaire for 332 outpatients with documented AF. Weight/height was measured and body mass index (kg/m(2)) calculated. Recent depression symptom severity was assessed using the Patient Health Questionnaire-9 questionnaire. Physical activity during the last month was assessed by questionnaire. AF symptom severity was assessed using the University of Toronto AF Severity scale. Multivariate linear regression was used to evaluate which factors were associated with AF symptom severity. Obesity in patients with AF is associated with increased depression severity. In bivariate analysis, increasing body mass index (p = 0.001), lower levels of physical activity (p <0.001), and more severe depression (p <0.001) were associated with worsened AF symptom severity. In multivariate analysis, only physical activity and depression persisted as significant predictors of AF symptom severity. In conclusion, although obesity likely contributes to the substrate predisposing to the development of AF, other factors may contribute to or mediate the worsened AF symptoms associated with obesity. Depression symptoms and physical inactivity, factors closely correlated with obesity, may exacerbate symptoms in patients with AF. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

The importance of proximal fusion level selection for outcomes of multi-level lumbar posterolateral fusion.

PubMed

Nam, Woo Dong; Cho, Jae Hwan

2015-03-01

There are few studies about risk factors for poor outcomes from multi-level lumbar posterolateral fusion limited to three or four level lumbar posterolateral fusions. The purpose of this study was to analyze the outcomes of multi-level lumbar posterolateral fusion and to search for possible risk factors for poor surgical outcomes. We retrospectively analyzed 37 consecutive patients who underwent multi-level lumbar or lumbosacral posterolateral fusion with posterior instrumentation. The outcomes were deemed either 'good' or 'bad' based on clinical and radiological results. Many demographic and radiological factors were analyzed to examine potential risk factors for poor outcomes. Student t-test, Fisher exact test, and the chi-square test were used based on the nature of the variables. Multiple logistic regression analysis was used to exclude confounding factors. Twenty cases showed a good outcome (group A, 54.1%) and 17 cases showed a bad outcome (group B, 45.9%). The overall fusion rate was 70.3%. The revision procedures (group A: 1/20, 5.0%; group B: 4/17, 23.5%), proximal fusion to L2 (group A: 5/20, 25.0%; group B: 10/17, 58.8%), and severity of stenosis (group A: 12/19, 63.3%; group B: 3/11, 27.3%) were adopted as possible related factors to the outcome in univariate analysis. Multiple logistic regression analysis revealed that only the proximal fusion level (superior instrumented vertebra, SIV) was a significant risk factor. The cases in which SIV was L2 showed inferior outcomes than those in which SIV was L3. The odds ratio was 6.562 (95% confidence interval, 1.259 to 34.203). The overall outcome of multi-level lumbar or lumbosacral posterolateral fusion was not as high as we had hoped it would be. Whether the SIV was L2 or L3 was the only significant risk factor identified for poor outcomes in multi-level lumbar or lumbosacral posterolateral fusion in the current study. Thus, the authors recommend that proximal fusion levels be carefully determined when multi-level lumbar fusions are considered.

The Importance of Proximal Fusion Level Selection for Outcomes of Multi-Level Lumbar Posterolateral Fusion

PubMed Central

Nam, Woo Dong

2015-01-01

Background There are few studies about risk factors for poor outcomes from multi-level lumbar posterolateral fusion limited to three or four level lumbar posterolateral fusions. The purpose of this study was to analyze the outcomes of multi-level lumbar posterolateral fusion and to search for possible risk factors for poor surgical outcomes. Methods We retrospectively analyzed 37 consecutive patients who underwent multi-level lumbar or lumbosacral posterolateral fusion with posterior instrumentation. The outcomes were deemed either 'good' or 'bad' based on clinical and radiological results. Many demographic and radiological factors were analyzed to examine potential risk factors for poor outcomes. Student t-test, Fisher exact test, and the chi-square test were used based on the nature of the variables. Multiple logistic regression analysis was used to exclude confounding factors. Results Twenty cases showed a good outcome (group A, 54.1%) and 17 cases showed a bad outcome (group B, 45.9%). The overall fusion rate was 70.3%. The revision procedures (group A: 1/20, 5.0%; group B: 4/17, 23.5%), proximal fusion to L2 (group A: 5/20, 25.0%; group B: 10/17, 58.8%), and severity of stenosis (group A: 12/19, 63.3%; group B: 3/11, 27.3%) were adopted as possible related factors to the outcome in univariate analysis. Multiple logistic regression analysis revealed that only the proximal fusion level (superior instrumented vertebra, SIV) was a significant risk factor. The cases in which SIV was L2 showed inferior outcomes than those in which SIV was L3. The odds ratio was 6.562 (95% confidence interval, 1.259 to 34.203). Conclusions The overall outcome of multi-level lumbar or lumbosacral posterolateral fusion was not as high as we had hoped it would be. Whether the SIV was L2 or L3 was the only significant risk factor identified for poor outcomes in multi-level lumbar or lumbosacral posterolateral fusion in the current study. Thus, the authors recommend that proximal fusion levels be carefully determined when multi-level lumbar fusions are considered. PMID:25729522

Intervening on risk factors for coronary heart disease: an application of the parametric g-formula.

PubMed

Taubman, Sarah L; Robins, James M; Mittleman, Murray A; Hernán, Miguel A

2009-12-01

Estimating the population risk of disease under hypothetical interventions--such as the population risk of coronary heart disease (CHD) were everyone to quit smoking and start exercising or to start exercising if diagnosed with diabetes--may not be possible using standard analytic techniques. The parametric g-formula, which appropriately adjusts for time-varying confounders affected by prior exposures, is especially well suited to estimating effects when the intervention involves multiple factors (joint interventions) or when the intervention involves decisions that depend on the value of evolving time-dependent factors (dynamic interventions). We describe the parametric g-formula, and use it to estimate the effect of various hypothetical lifestyle interventions on the risk of CHD using data from the Nurses' Health Study. Over the period 1982-2002, the 20-year risk of CHD in this cohort was 3.50%. Under a joint intervention of no smoking, increased exercise, improved diet, moderate alcohol consumption and reduced body mass index, the estimated risk was 1.89% (95% confidence interval: 1.46-2.41). We discuss whether the assumptions required for the validity of the parametric g-formula hold in the Nurses' Health Study data. This work represents the first large-scale application of the parametric g-formula in an epidemiologic cohort study.

Factors of working conditions and prolonged fatigue among teachers at public elementary and junior high schools.

PubMed

Shimizu, Midori; Wada, Koji; Wang, Guoqin; Kawashima, Masatoshi; Yoshino, Yae; Sakaguchi, Hiroko; Ohta, Hiroshi; Miyaoka, Hitoshi; Aizawa, Yoshiharu

2011-01-01

Prolonged fatigue among elementary and junior high school teachers not only damages their health but also affects the quality of education. The aim of this study was to determine the factors of working conditions associated with prolonged fatigue among teachers at public elementary and junior high schools. We distributed a self-reported, anonymous questionnaire to 3,154 teachers (1,983 in elementary schools, 1,171 in junior high schools) working in public schools in a city in Japan. They were asked to assess 18 aspects of their working conditions using a seven-point Likert scale. Prolonged fatigue was measured using the Japanese version of the checklist individual strength questionnaire. Multiple regression analysis was used to examine the association between working conditions and prolonged fatigue. Gender, age, and school type were introduced as confounders. In all, 2,167 teachers participated in this study. Results showed that qualitative and quantitative workload (time pressure due to heavy workload, interruptions, physically demanding job, extra work at home), communication with colleagues (poor communication, lack of support), and career factors (underestimation of performance by the board of education or supervisors, occupational position not reflecting training, lack of prospects for work, job insecurity) were associated with prolonged fatigue.

Initial evidence that polymorphisms in neurotransmitter-regulating genes contribute to being born small for gestational age

PubMed Central

Morgan, Angharad R.; Thompson, John M.D.; Waldie, Karen E.; Cornforth, Christine M.; Turic, Darko; Sonuga-Barke, Edmund J.S.; Lam, Wen-Jiun; Ferguson, Lynnette R.; Mitchell, Edwin A.

2012-01-01

Being born small for gestational age (SGA) is a putative risk factor for the development of later cognitive and psychiatric health problems. While the inter-uterine environment has been shown to play an important role in predicting birth weight, little is known about the genetic factors that might be important. Here we test the hypothesis that neurotransmitter-regulating genes implicated in psychiatric disorders previously shown to be associated with SGA (such as attention-deficit hyperactivity disorder) are themselves predictive of SGA. DNA was collected from 227 SGA and 319 appropriate for gestational age children taking part in the Auckland Birthweight Collaborative Study. Candidate single nucleotide polymorphisms in genes regulating activity within dopamine, serotonin, glutamate and gamma-aminobutyric acid pathways were genotyped. Multiple regression analysis, controlling for potentially confounding factors, supported nominally significant associations between SGA and single nucleotide polymorphisms in COMT, HTR2A, SLC1A1 and SLC6A1. This is the first evidence that genes implicated in psychiatric disorders previously linked to SGA status themselves predict SGA. This highlights the possibility that the link between SGA and psychiatric disorders such as attention-deficit hyperactivity disorder may in part be genetically determined – that SGA marks pre-existing genetic risk for later problems. PMID:27625810

Behavioral lifestyle and mental health status of Japanese factory workers.

PubMed

Ezoe, S; Morimoto, K

1994-01-01

Lifestyle factors, sometimes associated with physical health and mortality, have also been known to be associated with mental health status. This study seeks to correlate behavioral lifestyles with major components of mental health among Japanese factory workers. We administered the 28-item version of the General Health Questionnaire (GHQ-28) and a questionnaire concerning eight personal health practices to 2,132 male and 668 female factory workers at a camera-manufacturing company in Japan. There were strong negative relationships of a higher total number of favorable lifestyles as indicated by the Health Practice Index (HPI) to psychological distress and its components: somatic symptoms, anxiety-insomnia, and social dysfunction. After controlling for the effects of confounding factors that included age, marital status, and somatic condition, multiple logistic regression analysis indicated that five of the eight health factors among male workers--mental stress, nutritional balance, eating breakfast regularly, physical exercise, and working hours--were significantly related to the grade of psychological distress or its three components. Among female workers, five health practices, i.e., mental stress, physical exercise, sleeping hours, working hours, and cigarette smoking, were significantly associated with the grade of psychological distress or its three components. Good health practices might be individually and as a whole associated with better mental health status in factory workers.

Association of circulating ANGPTL 3, 4, and 8 levels with medical status in a population undergoing routine medical checkups: A cross-sectional study.

PubMed

Morinaga, Jun; Zhao, Jiabin; Endo, Motoyoshi; Kadomatsu, Tsuyoshi; Miyata, Keishi; Sugizaki, Taichi; Okadome, Yusuke; Tian, Zhe; Horiguchi, Haruki; Miyashita, Kazuya; Maruyama, Nobuhiro; Mukoyama, Masashi; Oike, Yuichi

2018-01-01

Angiopoietin-like proteins (ANGPTLs) 3, 4, and 8 reportedly contribute to progression of metabolic disease, a risk factor for cardiovascular disease (CVD). The purpose of this study was to investigate whether circulating ANGPTL levels are associated with CVD risk after adjustment for potential confounding factors. We conducted a single center, cross-sectional study of 988 Japanese subjects undergoing routine health checks. Serum ANGPTL3, 4, and 8 levels were measured using an enzyme-linked immunosorbent assay. Using multiple regression analysis we evaluated potential association of circulating ANGPTL3, 4, and 8 levels with general medical status including age, sex, smoking, drinking, obesity, hypertension, impaired glycometabolism, dyslipidemia, hyperuricemia, hepatic impairment, chronic kidney disease, anemia, cardiac abnormality, and inflammation. Circulating ANGPTL3 levels were relatively high in health-related categories of hepatic impairment and inflammation. Circulating ANGPTL4 levels were also significantly high in impaired glycometabolism or hepatic impairment but decreased in inflammation. Finally, increased ANGPTL8 levels were observed in obesity, impaired glycometabolism and dyslipidemia. Particularly, increased levels of circulating ANGPTL8 were positively correlated with circulating triglycerides and LDL-cholesterol levels and inversely correlated with circulating HDL-cholesterol levels. Circulating ANGPTL3, 4, and 8 levels reflect some risk factors for CVD development.

Serum 25-hydroxyvitamin D3 and body composition in an elderly cohort from Germany: a cross-sectional study

PubMed Central

2012-01-01

Background Emerging evidence indicates that there is an association between vitamin D and obesity. The aim of this study was to investigate whether the level of serum 25-hydroxyvitamin D3 [25(OH)D3] in the elderly is influenced by parameters of anthropometry and body composition independent of potential confounding lifestyle factors and the level of serum intact parathyroid hormone (iPTH). Methods Cross-sectional data of 131 independently living participants (90 women, 41 men; aged 66–96 years) of the longitudinal study on nutrition and health status in senior citizens of Giessen, Germany were analysed. Concentrations of 25(OH)D3 and iPTH were ascertained by an electrochemiluminescence immunoassay. Body composition was measured by a bioelectrical impedance analysis. We performed univariate and multiple regression analyses to examine the influence of body composition on 25(OH)D3 with adjustments for age, iPTH and lifestyle factors. Results In univariate regression analyses, 25(OH)D3 was associated with body mass index (BMI), hip circumference and total body fat (TBF) in women, but not in men. Using multiple regression analyses, TBF was shown to be a negative predictor of 25(OH)D3 levels in women even after controlling for age, lifestyle and iPTH (ß = −0.247; P = 0.016), whereas the associations between BMI, hip circumference and 25(OH)D3 lost statistical significance after adjusting for iPTH. In men, 25(OH)D3 was not affected by anthropometric or body composition variables. Conclusions The results indicate that 25(OH)D3 levels are affected by TBF, especially in elderly women, independent of lifestyle factors and iPTH. PMID:22607088

Vascular risk factor burden, atherosclerosis, and functional dependence in old age: a population-based study.

PubMed

Welmer, Anna-Karin; Liang, Yajun; Angleman, Sara; Santoni, Giola; Yan, Zhongrui; Cai, Chuanzhu; Qiu, Chengxuan

2014-08-01

Vascular risk factors such as hypertension and obesity have been associated with physical limitations among older adults. The purpose of this study is to examine whether individual and aggregated vascular risk factors (VRFs) are associated with functional dependence and to what extent carotid atherosclerosis (CAS) or peripheral artery disease (PAD) may mediate the possible associations of aggregated VRFs with functional dependence. This cross-sectional study included 1,451 community-living participants aged ≥60 years in the Confucius Hometown Aging Project of China. Data on demographic features, hypertension, high total cholesterol, obesity, smoking, physical inactivity, diabetes, CAS, PAD, and cardiovascular diseases (CVDs) were collected through an interview, a clinical examination, and laboratory tests. Functional dependence was defined as being dependent in at least one activity in the personal or instrumental activities of daily living. Data were analyzed using multiple logistic models controlling for potential confounders. We used the mediation model to explore the potential mediating effect of CAS and PAD on the associations of aggregated VRFs with functional dependence. Of the 1,451 participants, 222 (15.3%) had functional dependence. The likelihood of functional dependence increased linearly with increasing number of VRFs (hypertension, high total cholesterol, abdominal obesity, and physical inactivity) (p for trend <0.002). Mediation analysis showed that controlling for demographics and CVDs up to 11% of the total association of functional dependence with clustering VRFs was mediated by CAS and PAD. Aggregation of multiple VRFs is associated with an increased likelihood of functional dependence among Chinese older adults; the association is partially mediated by carotid and peripheral artery atherosclerosis independently of CVDs.

Raw garlic consumption as a protective factor for lung cancer, a population-based case-control study in a Chinese population

PubMed Central

Jin, Zi-Yi; Wu, Ming; Han, Ren-Qiang; Zhang, Xiao-Feng; Wang, Xu-Shan; Liu, Ai-Ming; Zhou, Jin-Yi; Lu, Qing-Yi; Zhang, Zuo-Feng; Zhao, Jin-Kou

2013-01-01

Protective effect of garlic on the development of cancer has been reported in vitro and in vivo experimental studies, however, few human epidemiological studies have evaluated the relationship. A population-based case-control study has been conducted in a Chinese population from 2003 to 2010, with the aim to explore the association between raw garlic consumption and lung cancer. Epidemiological data were collected by face-to-face interviews using a standard questionnaire among 1,424 lung cancer cases and 4,543 healthy controls. Unconditional logistic regression was employed to estimate adjusted odds ratios (OR) and their 95% confidence intervals (CIs), and to evaluate ratio of odds ratios (ROR) for multiplicative interactions between raw garlic consumption and other risk factors. After adjusting for potential confounding factors, raw garlic consumption of ≥ 2 times per week is inversely associated with lung cancer (OR = 0.56, 95% CI = 0.44-0.72) with a monotonic dose-response relationship (p for trend <0.001). Furthermore, strong interactions at either additive and/or multiplicative scales were observed between raw garlic consumption and tobacco smoking (Synergy Index (SI) = 0.70, 95% CI = 0.57-0.85; and ROR = 0.78, 95% CI = 0.67-0.90), as well as high-temperature cooking oil fume (ROR = 0.77, 95% CI = 0.59-1.00). In conclusion, protective association between intake of raw garlic and lung cancer has been observed with a dose-response pattern, suggesting that garlic may potentially serve as a chemopreventive agent for lung cancer. Effective components in garlic in lung cancer chemoprevention warrant further in-depth investigation. PMID:23658367

Stability and change of body mass index as a predictor of disability pension.

PubMed

Ropponen, Annina; Silventoinen, Karri; Koskenvuo, Markku; Svedberg, Pia; Kaprio, Jaakko

2016-06-01

To investigate whether stability or change in body mass index (BMI) predict disability pension (DP) due to musculoskeletal diagnosis (MSD) when controlling for familial confounding. Our study cohort consisted of 17,169 Finnish twins born before 1958. Data on BMI and multiple covariates from questionnaires in 1975 and 1981 were included and DPs were collected from the national pension registers until the end of 2004. Cox proportional hazards regression models with Hazard Ratios (HR) and 95% Confidence Intervals (CI) were used for statistical analyses. General DP was granted to 2853 individuals and DP due to MSD to 1143 individuals during the 23-year follow-up. A one-unit increase in BMI in both 1975 (HR 1.08, 95% CI 1.05, 1.10) and 1981 (HR 1.06, 95% CI 1.04, 1.07), as well as the stability of and change in BMI from 1975 to 1981 were all associated with an increased risk of DP. These associations held in the analyses controlling for multiple covariates (age, sex, socioeconomic status, education, marital status, leisure-time physical activity, and musculoskeletal pain), and mainly also familial confounding, that is, genetics and shared environment. HR for stable obesity was 2.28 (95% CI 1.69, 3.08) for DP due to MSD, and 1.91 (95% CI 1.56, 2.34) for general DP in the fully adjusted models. CONCLUSIONS BMI IS AN EARLY PREDICTOR OF GENERAL DP AND ALSO OF DP DUE TO MSD OWING TO THE INDEPENDENCY OF VARIOUS COVARIATES AND POTENTIALLY ALSO FAMILIAL CONFOUNDING, BMI MAY POSSIBLY HAVE A DIRECT EFFECT ON THE RISK OF DP. © 2016 the Nordic Societies of Public Health.

Combining evidence from multiple electronic health care databases: performances of one-stage and two-stage meta-analysis in matched case-control studies.

PubMed

La Gamba, Fabiola; Corrao, Giovanni; Romio, Silvana; Sturkenboom, Miriam; Trifirò, Gianluca; Schink, Tania; de Ridder, Maria

2017-10-01

Clustering of patients in databases is usually ignored in one-stage meta-analysis of multi-database studies using matched case-control data. The aim of this study was to compare bias and efficiency of such a one-stage meta-analysis with a two-stage meta-analysis. First, we compared the approaches by generating matched case-control data under 5 simulated scenarios, built by varying: (1) the exposure-outcome association; (2) its variability among databases; (3) the confounding strength of one covariate on this association; (4) its variability; and (5) the (heterogeneous) confounding strength of two covariates. Second, we made the same comparison using empirical data from the ARITMO project, a multiple database study investigating the risk of ventricular arrhythmia following the use of medications with arrhythmogenic potential. In our study, we specifically investigated the effect of current use of promethazine. Bias increased for one-stage meta-analysis with increasing (1) between-database variance of exposure effect and (2) heterogeneous confounding generated by two covariates. The efficiency of one-stage meta-analysis was slightly lower than that of two-stage meta-analysis for the majority of investigated scenarios. Based on ARITMO data, there were no evident differences between one-stage (OR = 1.50, CI = [1.08; 2.08]) and two-stage (OR = 1.55, CI = [1.12; 2.16]) approaches. When the effect of interest is heterogeneous, a one-stage meta-analysis ignoring clustering gives biased estimates. Two-stage meta-analysis generates estimates at least as accurate and precise as one-stage meta-analysis. However, in a study using small databases and rare exposures and/or outcomes, a correct one-stage meta-analysis becomes essential. Copyright © 2017 John Wiley & Sons, Ltd.

Bark analysis as a guide to cassava nutrition in Sierra Leone

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

Godfrey-Sam-Aggrey, W.; Garber, M.J.

1979-01-01

Cassava main stem barks from two experiments in which similar fertilizers were applied directly in a 2/sup 5/ confounded factorial design were analyzed and the bark nutrients used as a guide to cassava nutrition. The application of multiple regression analysis to the respective root yields and bark nutrient concentrations enable nutrient levels and optimum adjusted root yields to be derived. Differences in bark nutrient concentrations reflected soil fertility levels. Bark analysis and the application of multiple regression analysis to root yields and bark nutrients appear to be useful tools for predicting fertilizer recommendations for cassava production.

The Association Between Headaches and Temporomandibular Disorders is Confounded by Bruxism and Somatic Symptoms.

PubMed

van der Meer, Hedwig A; Speksnijder, Caroline M; Engelbert, Raoul H H; Lobbezoo, Frank; Nijhuis-van der Sanden, Maria W G; Visscher, Corine M

2017-09-01

The objective of this observational study was to establish the possible presence of confounders on the association between temporomandibular disorders (TMD) and headaches in a patient population from a TMD and Orofacial Pain Clinic. Several subtypes of headaches have been diagnosed: self-reported headache, (probable) migraine, (probable) tension-type headache, and secondary headache attributed to TMD. The presence of TMD was subdivided into 2 subtypes: painful TMD and function-related TMD. The associations between the subtypes of TMD and headaches were evaluated by single regression models. To study the influence of possible confounding factors on this association, the regression models were extended with age, sex, bruxism, stress, depression, and somatic symptoms. Of the included patients (n=203), 67.5% experienced headaches. In the subsample of patients with a painful TMD (n=58), the prevalence of self-reported headaches increased to 82.8%. The associations found between self-reported headache and (1) painful TMD and (2) function-related TMD were confounded by the presence of somatic symptoms. For probable migraine, both somatic symptoms and bruxism confounded the initial association found with painful TMD. The findings of this study imply that there is a central working mechanism overlapping TMD and headache. Health care providers should not regard these disorders separately, but rather look at the bigger picture to appreciate the complex nature of the diagnostic and therapeutic process.

Perceived fairness of pay among people with and without disabilities: a propensity score matched analysis of working Australians.

PubMed

Milner, Allison; Aitken, Zoe; Krnjacki, Lauren; Bentley, Rebecca; Blakely, Tony; LaMontagne, Anthony D; Kavanagh, Anne M

2015-09-01

Equity and fairness at work are associated with a range of organizational and health outcomes. Past research suggests that workers with disabilities experience inequity in the workplace. It is difficult to conclude whether the presence of disability is the reason for perceived unfair treatment due to the possible confounding of effect estimates by other demographic or socioeconomic factors. The data source was the Household, Income, and Labor Dynamics in Australia (HILDA) survey (2001-2012). Propensity for disability was calculated from logistic models including gender, age, education, country of birth, and father's occupational skill level as predictors. We then used nearest neighbor (on propensity score) matched analysis to match workers with disabilities to workers without disability. Results suggest that disability is independently associated with lower fairness of pay after controlling for confounding factors in the propensity score matched analysis; although results do suggest less than half a standard deviation difference, indicating small effects. Similar results were apparent in standard multivariable regression models and alternative propensity score analyses (stratification, covariate adjustment using the propensity score, and inverse probability of treatment weighting). Whilst neither multivariable regression nor propensity scores adjust for unmeasured confounding, and there remains the potential for other biases, similar results for the two methodological approaches to confounder adjustment provide some confidence of an independent association of disability with perceived unfairness of pay. Based on this, we suggest that the disparity in the perceived fairness of pay between people with and without disabilities may be explained by worse treatment of people with disabilities in the workplace.

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.

Cognitively-Impaired-Not-Demented Status Moderates the Time-Varying Association between Finger Tapping Inconsistency and Executive Performance.

PubMed

Halliday, Drew W R; Stawski, Robert S; MacDonald, Stuart W S

2017-02-01

Response time inconsistency (RTI) in cognitive performance predicts deleterious health outcomes in late-life; however, RTI estimates are often confounded by additional influences (e.g., individual differences in learning). Finger tapping is a basic sensorimotor measure largely independent of higher-order cognition that may circumvent such confounds of RTI estimates. We examined the within-person coupling of finger-tapping mean and RTI on working memory, and the moderation of these associations by cognitive status. A total of 262 older adults were recruited and classified as controls, cognitively-impaired-not-demented (CIND) unstable or CIND stable. Participants completed finger-tapping and working-memory tasks during multiple weekly assessments, repeated annually for 4 years. Within-person coupling estimates from multilevel models indicated that on occasions when RTI was greater, working-memory response latency was slower for the CIND-stable, but not for the CIND-unstable or control individuals. The finger-tapping task shows potential for minimizing confounds on RTI estimates, and for yielding RTI estimates sensitive to central nervous system function and cognitive status. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Appropriate and inappropriate methods for investigating the "gateway" hypothesis, with a review of the evidence linking prior snus use to later cigarette smoking.

PubMed

Lee, Peter N

2015-03-20

The "gateway hypothesis" usually refers to the possibility that the taking up of habit A, which is considered harmless (or less harmful), may lead to the subsequent taking up of another habit, B, which is considered harmful (or more harmful). Possible approaches to designing and analysing studies to test the hypothesis are discussed. Evidence relating to the use of snus (A) as a gateway for smoking (B) is then evaluated in detail. The importance of having appropriate data available on the sequence of use of A and B and on other potential confounding factors that may lead to the taking up of B is emphasised. Where randomised trials are impractical, the preferred designs include the prospective cohort study in which ever use of A and of B is recorded at regular intervals, and the cross-sectional survey in which time of starting to use A and B is recorded. Both approaches allow time-stratified analytical methods to be used, in which, in each time period, risk of initiating B among never users of B at the start of the interval is compared according to prior use of A. Adjustment in analysis for the potential confounding factors is essential. Of 11 studies of possible relevance conducted in Sweden, Finland or Norway, only one seriously addresses potential confounding by those other factors involved in the initiation of smoking. Furthermore, 5 of the 11 studies are of a design that does not allow proper testing of the gateway hypothesis for various reasons, and the analysis is unsatisfactory, sometimes seriously, in all the remaining six. While better analyses could be attempted for some of the six studies identified as having appropriate design, the issues of confounding remain, and more studies are clearly needed. To obtain a rapid answer, a properly designed cross-sectional survey is recommended.

High birth weight and perinatal mortality among siblings: A register based study in Norway, 1967-2011.

PubMed

Kristensen, Petter; Keyes, Katherine M; Susser, Ezra; Corbett, Karina; Mehlum, Ingrid Sivesind; Irgens, Lorentz M

2017-01-01

Perinatal mortality according to birth weight has an inverse J-pattern. Our aim was to estimate the influence of familial factors on this pattern, applying a cohort sibling design. We focused on excess mortality among macrosomic infants (>2 SD above the mean) and hypothesized that the birth weight-mortality association could be explained by confounding shared family factors. We also estimated how the participant's deviation from mean sibling birth weight influenced the association. We included 1 925 929 singletons, born term or post-term to mothers with more than one delivery 1967-2011 registered in the Medical Birth Registry of Norway. We examined z-score birth weight and perinatal mortality in random-effects and sibling fixed-effects logistic regression models including measured confounders (e.g. maternal diabetes) as well as unmeasured shared family confounders (through fixed effects models). Birth weight-specific mortality showed an inverse J-pattern, being lowest (2.0 per 1000) at reference weight (z-score +1 to +2) and increasing for higher weights. Mortality in the highest weight category was 15-fold higher than reference. This pattern changed little in multivariable models. Deviance from mean sibling birth weight modified the mortality pattern across the birth weight spectrum: small and medium-sized infants had increased mortality when being smaller than their siblings, and large-sized infants had an increased risk when outweighing their siblings. Maternal diabetes and birth weight acted in a synergistic fashion with mortality among macrosomic infants in diabetic pregnancies in excess of what would be expected for additive effects. The inverse J-pattern between birth weight and mortality is not explained by measured confounders or unmeasured shared family factors. Infants are at particularly high mortality risk when their birth weight deviates substantially from their siblings. Sensitivity analysis suggests that characteristics related to maternal diabetes could be important in explaining the increased mortality among macrosomic infants.

Does caregiving cause psychological distress? The case for familial and genetic vulnerabilities in female twins.

PubMed

Vitaliano, Peter P; Strachan, Eric; Dansie, Elizabeth; Goldberg, Jack; Buchwald, Dedra

2014-04-01

Informal caregiving can be deleterious to mental health, but research results are inconsistent and may reflect an interaction between caregiving and vulnerability to stress. We examined psychological distress among 1,228 female caregiving and non-caregiving twins. By examining monozygotic and dizygotic twin pairs discordant for caregiving, we assessed the extent to which distress is directly related to caregiving or confounded by common genes and environmental exposures. Caregiving was associated with distress as measured by mental health functioning, anxiety, perceived stress, and depression. The overall association between caregiving and distress was confounded by common genes and environment for mental health functioning, anxiety, and depression. Common environment also confounded the association of caregiving and perceived stress. Vulnerability to distress is a factor in predicting caregivers' psychosocial functioning. Additional research is needed to explicate the mechanisms by which common genes and environment increase the risk of distress among informal caregivers.

Association between methylmercury and cardiovascular risk factors in a native population of Quebec (Canada): a retrospective evaluation.

PubMed

Valera, Beatriz; Dewailly, Eric; Poirier, Paul

2013-01-01

Epidemiological evidence suggests a negative impact of methylmercury (MeHg) on cardiovascular risk factors such as blood pressure (BP) and heart rate (HR). This issue is of concern in Arctic populations such as in the Inuit of Nunavik since this contaminant is accumulated in fish and marine mammals, which still represent the subsistence diet of this population. We examined the associations between MeHg and BP and resting HR among Inuit adults. The "Santé Quebec" health survey was conducted in 1992 in the 14 villages of Nunavik and a complete set of data was obtained for 313 Inuit adults≥18 years. Blood samples were collected in order to determine total mercury, lead, total polychlorinated biphenyls (PCBs), n-3 polyunsaturated fatty acids (PUFAs), fasting glucose and lipid profile while socio-demographic variables were obtained through questionnaires. Anthropometric measurements as well as BP and resting HR were obtained using standardised protocols. Pulse pressure (PP: systolic BP minus diastolic BP) was also calculated. Multiple linear regression was used in order to determine the change in the dependent variables associated with the quartiles of MeHg concentration, taking the quartile 1 as reference. The mean age of the participants was 38±14 years and the sample was composed of 132 men (42.2%) and 181 women (57.8%). MeHg geometric mean was 15.4 μg/L (95%CI: 13.9-17.0) and levels ranged from 0.8 to 112.0 μg/L. Resting HR increased linearly across quartiles of blood MeHg concentration after adjusting for confounders (p for trend=0.02). An increase of 6.9 beats per minute (bpm) between the 4th and 1st quartile was observed after adjusting for confounders. No significant association was observed between blood MeHg and systolic BP, diastolic BP or PP. MeHg was associated with increasing resting HR after considering traditional risk factors as well as other contaminants (lead and total PCBs) and n-3 PUFAs. In contrast, no significant association with blood pressure was observed in this study. Copyright © 2012 Elsevier Inc. All rights reserved.

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.

Assisted Reproductive Technology and Risk for Autism Spectrum Disorder

ERIC Educational Resources Information Center

Zachor, Ditza A.; Itzchak, E. Ben

2011-01-01

Epidemiologic studies on maternal and pregnancy risk factors for autism spectrum disorder (ASD), including use of assisted reproductive technology (ART), found conflicting results. This study included the following aims: to assess frequencies of ART in a large ASD group; to examine confounding birth and familial risk factors in the ASD with ART…

Maternal Age at Childbirth and Offspring Disruptive Behaviors: Testing the Causal Hypothesis

ERIC Educational Resources Information Center

D'Onofrio, Brian M.; Goodnight, Jackson A.; Van Hulle, Carol A.; Rodgers, Joseph Lee; Rathouz, Paul J.; Waldman, Irwin D.; Lahey, Benjamin B.

2009-01-01

Background: Recent studies suggest that the association between maternal age at childbearing (MAC) and children's disruptive behaviors is the result of family factors that are confounded with both variables, rather than a casual effect of environmental factors specifically related to MAC. These studies, however, relied on restricted samples and…

Child Migration and Academic Performance: The Case of Basic Education in Ghana

ERIC Educational Resources Information Center

Tamanja, Emmanuel Makabu J.

2016-01-01

The nexus between migration and academic performance is complex and difficult to extricate. Not only are there several factors affecting academic performance, but also many of these factors are confounding, making it difficult to identify and isolate in order to address. Furthermore, the discourse appears silent on the nexus between child…

Assay dilution factors confound measures of total antioxidant capacity in polyphenol-rich juices

USDA-ARS?s Scientific Manuscript database

The extent to which sample dilution factor (DF) affects Total Antioxidant Capacity (TAC) values is poorly understood. Thus, we examined the impact of DF on the ORAC, FRAP, DPPH, and Total Phenols (TP) assays using pomegranate juice (PJ), grape juice (GJ), selected flavonoids, ascorbic acid, and ella...

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.

Brain natriuretic peptide in patients with congestive heart failure and central sleep apnea.

PubMed

Carmona-Bernal, Carmen; Quintana-Gallego, Esther; Villa-Gil, Manuel; Sánchez-Armengol, Angeles; Martínez-Martínez, Angel; Capote, Francisco

2005-05-01

To assess the possible relationship between Cheyne-Stokes respiration (CSR) associated with central sleep apnea (CSA) syndrome and brain natriuretic peptide (BNP) in an outpatient population presenting with stable congestive heart failure (CHF). Ninety patients with CHF due to systolic dysfunction (left ventricular ejection fraction

Radiographic bone loss in a Scottish non-smoking Type 1 Diabetes mellitus population; a Bitewing Radiographic Study.

PubMed

Plessas, Anastasios; Robertson, Douglas P; Hodge, Penny J

2018-05-15

The dental complications of uncontrolled diabetes include reduced salivary flow rate, candidiasis and periodontal manifestations. A recent meta-analysis concluded that diabetes patients have a significantly higher severity, but not extent, of destructive periodontal disease than non-diabetes people. The authors reported that most type-1 diabetes studies using dental radiographic data have not controlled for confounding factors such as smoking. The aim of this cross-sectional study was to compare radiographic alveolar bone loss between type 1 diabetes (T1DM) and non-diabetes (NDM) participants in a Scottish non-smoking population. Digital bitewing radiographs for 174 Scottish adult never or ex-smoker (> 5 years) participants (108 T1DM, 66 NDS), recruited from outpatient clinics throughout Greater Glasgow and Clyde, were included in the analysis. A single blinded, trained and calibrated examiner recorded the radiographic bone loss seen on bitewing radiographs using the digital screen caliper. The bone loss was measured as the distance between the cemento-enamel junction (CEJ) and the deepest radiographic alveolar bone margin interproximally of each tooth. T1DM participants had more radiographic alveolar bone loss throughout the all teeth measured (median:1.27 mm vs 1.06 mm, P < 0.001) and more than a two fold increase in the risk of having sites with ≥2 mm periodontal destruction (OR = 2.297, 95%CI 1.058-4.986, P = 0.036) compared with non-diabetes subjects. Patients suffering from type 1 diabetes are at higher risk of periodontitis even when controlling for multiple possible confounding factors and this difference can be detected on routine dental radiographs at an early stage. These data confirm radiographically the previously reported association between T1DM and periodontal bone loss. This article is protected by copyright. All rights reserved. © 2018 American Academy of Periodontology.

Second-generation corneal deformation signal waveform analysis in normal, forme fruste keratoconic, and manifest keratoconic corneas after statistical correction for potentially confounding factors.

PubMed

Zhang, Lijun; Danesh, Jennifer; Tannan, Anjali; Phan, Vivian; Yu, Fei; Hamilton, D Rex

2015-10-01

To evaluate the difference in corneal biomechanical waveform parameters between manifest keratoconus, forme fruste keratoconus, and healthy eyes with a second-generation biomechanical waveform analyzer (Ocular Response Analyzer 2). Jules Stein Eye Institute, University of California, Los Angeles, California, USA. Retrospective chart review. The biomechanical waveform analyzer was used to obtain corneal hysteresis (CH), corneal resistance factor (CRF), and 37 biomechanical waveform parameters in manifest keratoconus eyes, forme fruste keratoconus eyes, and healthy eyes. Useful distinguishing parameters were found using t tests and a multivariable logistic regression model with stepwise variable selection. Potential confounders were controlled for. The study included 68 manifest keratoconus eyes, 64 forme fruste keratoconus eyes, and 249 healthy eyes. There was a statistical difference in the mean CRF between the normal group (10.2 mm Hg ± 1.7 [SD]) and keratoconus group (6.3 ± 1.9 mm Hg) (P = .003), and between the normal group and the forme fruste keratoconus group (7.8 ± 1.4 mm Hg) (P < .0001). There was no statistical difference in the mean CH between the normal group and the keratoconus group or the forme fruste keratoconus group. The CRF, height of peak 1 (P1) (P = .001), downslope of P1 (dslope1) (P = .027), upslope of peak 2 (P2) (P = .004), and downslope of P2 (P = .006) distinguished the normal group from the keratoconus groups. The CRF, downslope of P2 derived from upper 50% of applanation peak (P = .035), dslope1 (P = .014), and upslope of P1 (P = .008) distinguished the normal group from the forme fruste keratoconus group. Differences in multiple biomechanical waveform parameters can differentiate between healthy and diseased conditions and might improve early diagnosis of keratoconus and forme fruste keratoconus. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Factors associated with employment status before and during pregnancy: Implications for studies of pregnancy outcomes.

PubMed

Rocheleau, Carissa M; Bertke, Stephen J; Lawson, Christina C; Romitti, Paul A; Desrosiers, Tania A; Agopian, Aaron J; Bell, Erin; Gilboa, Suzanne M

2017-04-01

Potential confounding or effect modification by employment status is frequently overlooked in pregnancy outcome studies. To characterize how employed and non-employed women differ, we compared demographics, behaviors, and reproductive histories by maternal employment status for 8,343 mothers of control (non-malformed) infants in the National Birth Defects Prevention Study (1997-2007) and developed a multivariable model for employment status anytime during pregnancy and the 3 months before conception. Sixteen factors were independently associated with employment before or during pregnancy, including: maternal age, pre-pregnancy body mass index, pregnancy intention, periconceptional/first trimester smoking and alcohol consumption, and household income. Employment status was significantly associated with many common risk factors for adverse pregnancy outcomes. Pregnancy outcome studies should consider adjustment or stratification by employment status. In studies of occupational exposures, these differences may cause uncontrollable confounding if non-employed women are treated as unexposed instead of excluded from analysis. Am. J. Ind. Med. 60:329-341, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The link between early onset drinking and early onset alcohol-impaired driving in young males.

PubMed

Zhang, Lening; Wieczorek, William F; Welte, John W

2014-05-01

Young drivers represent a disproportionate number of the individuals involved in alcohol-impaired driving. Although there is a known association between drinking and alcohol-impaired driving in young drivers, the link between early onset drinking and early onset alcohol-impaired driving has not been explored. The present study aimed to assess this link along with potentially confounding factors. The assessment used a proportional hazards model with data collected from the Buffalo Longitudinal Study of Young Men, a population-based sample of 625 males at aged 16-19. Controlling for the effects of potentially relevant confounds, the early onset of drinking was the most influential factor in predicting the early onset of alcohol-impaired driving. Race and the early onset of other forms of delinquency also played a significant role in the early onset of alcohol-impaired driving. Preventing an early start of drinking among adolescents may be the most critical factor to address in preventing an early start of alcohol-impaired driving.

Family-Environmental Factors Associated with Attention Deficit Hyperactivity Disorder in Chinese Children: A Case-Control Study

PubMed Central

du Prel Carroll, Xianming; Yi, Honggang; Liang, Yuezhu; Pang, Ke; Leeper-Woodford, Sandra; Riccardi, Patrizia; Liang, Xianhong

2012-01-01

Background Attention deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders, affecting an estimated 5 to 12% of school-aged children worldwide. From 15 to 19 million Chinese children suffer from ADHD. The aim of this study was to investigate the association between family-environmental factors and ADHD in a sample of Chinese children. Methods A pair-matched, case-control study was conducted with 161 ADHD children and 161 non-ADHD children of matching age and sex, all from 5–18 years of age. The ADHD subjects and the normal controls were all evaluated via structured diagnostic interviews. We examined the association between family-environmental factors and ADHD using the conditional multiple logistic regression with backward stepwise selection to predict the associated factors of ADHD. Results Having experienced emotional abuse and being a single child were both significant factors associated with children diagnosed with ADHD. ADHD subjects were more likely to have suffered from emotional abuse (OR = 11.09, 95% CI = 2.15–57.29, P = 0.004) and have been a single child in the family (OR = 6.32, 95% CI = 2.09–19.14, P = 0.001) when compared to normal controls. The results were not modified by other confounding factors. Conclusion Our findings provide evidence that family-environmental factors are associated with ADHD among children in China. These findings, if confirmed by future research, may help to decrease ADHD by increasing the awareness of the effects of childhood emotional abuse. PMID:23209774

Gout in African Americans.

PubMed

Krishnan, Eswar

2014-09-01

African Americans have a substantially higher prevalence of risk factors for gout than Caucasians. The aim of the present study was to compare the risk for incident gout among African Americans and Caucasians. Incidence rates of physician-diagnosed gout among 11,559 Caucasian men and 931 African American men aged 35 to 57 years and at high cardiovascular risk, observed for 7 years as a part of the Multiple Risk Factor Intervention Trial, were analyzed. Cox regression models were used to account for potential confounding by age, body mass index, diuretic use, hypertension and diabetes status, aspirin and alcohol consumption, and kidney disease. At baseline, after accounting for risk factors, African Americans had a 14% lower prevalence of hyperuricemia than Caucasians. Incidence of gout increased with increasing prevalence of risk factors in both Caucasians and African Americans. Ethnic disparities in incidence rates were most apparent among those without other risk factors for gout. In separate Cox regression models, after accounting for risk factors, African American ethnicity was associated with a hazard ratio of 0.78 (95% confidence interval [CI], 0.66-0.93) for physician-diagnosed gout and 0.88 (95% CI, 0.85-0.90) for incident hyperuricemia. Significant interactions were observed; the association was the strongest (hazard ratio 0.47; 0.37-0.60). These associations were unaffected by addition of serum urate as a covariate or by using alternate case definitions for gout. After accounting for the higher prevalence of risk factors, African American ethnicity is associated with a significantly lower risk for gout and hyperuricemia compared with Caucasian ethnicity. Copyright © 2014 Elsevier Inc. All rights reserved.

Hospital ownership and financial performance: what explains the different findings in the empirical literature?

PubMed

Shen, Yu-Chu; Eggleston, Karen; Lau, Joseph; Schmid, Christopher H

2007-01-01

This study applies meta-analytic methods to conduct a quantitative review of the empirical literature on hospital ownership since 1990. We examine four financial outcomes across 40 studies: cost, revenue, profit margin, and efficiency. We find that variation in the magnitudes of ownership effects can be explained by a study's research focus and methodology. Studies using empirical methods that control for few confounding factors tend to find larger differences between for-profit and not-for-profit hospitals than studies that control for a wider range of confounding factors. Functional form and sample size also matter. Failure to apply log transformation to highly skewed expenditure data yields misleadingly large estimated differences between for-profits and not-for-profits. Studies with fewer than 200 observations also produce larger point estimates and wide confidence intervals.

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.

Parental mental health, childhood psychiatric disorders, and asthma attacks in island Puerto Rican youth.

PubMed

Ortega, Alexander N; Goodwin, Renee D; McQuaid, Elizabeth L; Canino, Glorisa

2004-01-01

Previous research documents an association of poor parental mental health with asthma in children. This study aims to determine whether the associations between parental mental health problems and childhood asthma attacks persist after controlling for childhood anxiety and depression and other confounding factors. A community household sample of youth ages 4 to 17 years and their primary caregivers from the US Commonwealth of Puerto Rico was studied to determine the associations between parental mental health and childhood asthma attacks. Regression models that predicted asthma attacks in youth controlled for parental mental health problems, childhood anxiety and depression, zone of residence, and parents' age, education, and perception of poverty. After adjusting for children's depressive and anxiety disorders as well as other important confounders, associations between parental depression, suicide attempts, ataque de nervios, and history of mental health treatment and asthma attacks in offspring, by parental report, persisted. Additionally, the frequency of parental mental health problems was associated with children's asthma attacks. Parents with mental health problems were more likely to report histories of asthma attacks in their children compared with parents without mental health problems in Puerto Rico. These associations were not attributable to internalizing disorders in youth but persisted independent of childhood psychopathology and other confounding factors. Clinicians and researchers should recognize the relations between poor parental mental health and childhood asthma and explore the potential role of family psychosocial and behavioral factors related to the manifestation of the disease.

The effects of sleep duration on the incidence of cardiovascular events among middle-aged male workers in Japan.

PubMed

Hamazaki, Yuko; Morikawa, Yuko; Nakamura, Koshi; Sakurai, Masaru; Miura, Katsuyuki; Ishizaki, Masao; Kido, Teruhiko; Naruse, Yuchi; Suwazono, Yasushi; Nakagawa, Hideaki

2011-09-01

Although previous epidemiological studies have investigated the relationship between sleep duration and various cardiovascular events, the results have been inconsistent. Accordingly, we conducted a follow-up survey to investigate the relationship between sleep duration and cardiovascular events among male workers, accounting for occupational factors that might confound the true relationship. A total of 2282 male employees aged 35-54 years based in a factory in Japan were followed for 14 years. The risk of cardiovascular events was compared among 4 groups stratified based on sleep duration at baseline (<6, 6-6.9, 7-7.9, and ≥8 hours). Cardiovascular events included stroke, coronary events and sudden cardiac death. The hazard ratios for events were calculated using a Cox proportional hazards model, with the 7-7.9-hour group serving as a reference. The model was adjusted for potential confounders including traditional cardiovascular risk factors and working characteristics. During 14 years of follow-up, 64 cardiovascular events were recorded including 30 strokes, 27 coronary events and 7 sudden cardiac deaths. After adjustment for possible confounders, the hazard ratios for cardiovascular and coronary events in the <6-hour group were 3.49 [95% confidence interval (95% CI) 1.30-9.40] and 4.95 (95% CI 1.31-18.73), respectively. There was no significant increment in the risk of stroke for any sleep duration groups. Short sleep duration (<6 hours) was a significant risk factor for coronary events in a Japanese male working population.

An Association between Air Pollution and Daily Outpatient Visits for Respiratory Disease in a Heavy Industry Area

PubMed Central

Wang, Kuo-Ying; Chau, Tang-Tat

2013-01-01

In this work we used daily outpatient data from the Landseed Hospital in a heavily industrial area in northern Taiwan to study the associations between daily outpatient visits and air pollution in the context of a heavily polluted atmospheric environment in Chung-Li area during the period 2007–2011. We test the normality of each data set, control for the confounding factors, and calculate correlation coefficient between the outpatient visits and air pollution and meteorology, and use multiple linear regression analysis to seek significance of these associations. Our results show that temperature and relative humidity tend to be negatively associated with respiratory diseases. NO and are two main air pollutants that are positively associated with respiratory diseases, followed by , , , CO, and . Young outpatients (age 0–15 years) are most sensitive to changing air pollution and meteorology factors, followed by the eldest (age 66 years) and age 16–65 years of outpatients. Outpatients for COPD diseases are most sensitive to air pollution and meteorology factors, followed by allergic rhinitis, asthma, and pneumonia diseases. In the context of sex difference to air pollution and meteorological factors, male outpatients are more sensitive than female outpatients in the 16–65 age groups, while female outpatients are more sensitive than male outpatients in the young 0–15 age groups and in the eldest age groups. In total, female outpatients are more sensitive to air pollution and meteorological factors than male outpatients. PMID:24204573

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.

A multifactorial model of masticatory performance: the Suita study.

PubMed

Kosaka, T; Ono, T; Kida, M; Kikui, M; Yamamoto, M; Yasui, S; Nokubi, T; Maeda, Y; Kokubo, Y; Watanabe, M; Miyamoto, Y

2016-05-01

Previous studies have identified various factors related to masticatory performance. This study was aimed to investigate variations and impacts of factors related to masticatory performance among different occlusal support areas in general urban population in Japan. A total of 1875 Japanese subjects (mean age: 66·7 years) were included in the Suita study. Periodontal status was evaluated using the Community Periodontal Index (CPI). The number of functional teeth and occlusal support areas (OSA) were recorded, and the latter divided into three categories of perfect, decreased and lost OSA based on the Eichner Index. Masticatory performance was determined by means of test gummy jelly. For denture wearers, masticatory performance was measured with the dentures in place. The multiple linear regression analysis showed that, when controlling for other variables, masticatory performance was significantly associated with sex, number of functional teeth, maximum bite force and periodontal status in perfect OSA. Masticatory performance was significantly associated with number of functional teeth, maximum bite force and periodontal status in decreased OSA. In lost OSA, masticatory performance was significantly associated with maximum bite force. Maximum bite force was a factor significantly influencing masticatory performance that was common to all OSA groups. After controlling for possible confounding factors, the number of functional teeth and periodontal status were common factors in the perfect and decreased OSA groups, and only sex was significant in the perfect OSA group. These findings may help in providing dietary guidance to elderly people with tooth loss or periodontal disease. © 2015 John Wiley & Sons Ltd.

A comparison of estimators from self-controlled case series, case-crossover design, and sequence symmetry analysis for pharmacoepidemiological studies.

PubMed

Takeuchi, Yoshinori; Shinozaki, Tomohiro; Matsuyama, Yutaka

2018-01-08

Despite the frequent use of self-controlled methods in pharmacoepidemiological studies, the factors that may bias the estimates from these methods have not been adequately compared in real-world settings. Here, we comparatively examined the impact of a time-varying confounder and its interactions with time-invariant confounders, time trends in exposures and events, restrictions, and misspecification of risk period durations on the estimators from three self-controlled methods. This study analyzed self-controlled case series (SCCS), case-crossover (CCO) design, and sequence symmetry analysis (SSA) using simulated and actual electronic medical records datasets. We evaluated the performance of the three self-controlled methods in simulated cohorts for the following scenarios: 1) time-invariant confounding with interactions between the confounders, 2) time-invariant and time-varying confounding without interactions, 3) time-invariant and time-varying confounding with interactions among the confounders, 4) time trends in exposures and events, 5) restricted follow-up time based on event occurrence, and 6) patient restriction based on event history. The sensitivity of the estimators to misspecified risk period durations was also evaluated. As a case study, we applied these methods to evaluate the risk of macrolides on liver injury using electronic medical records. In the simulation analysis, time-varying confounding produced bias in the SCCS and CCO design estimates, which aggravated in the presence of interactions between the time-invariant and time-varying confounders. The SCCS estimates were biased by time trends in both exposures and events. Erroneously short risk periods introduced bias to the CCO design estimate, whereas erroneously long risk periods introduced bias to the estimates of all three methods. Restricting the follow-up time led to severe bias in the SSA estimates. The SCCS estimates were sensitive to patient restriction. The case study showed that although macrolide use was significantly associated with increased liver injury occurrence in all methods, the value of the estimates varied. The estimations of the three self-controlled methods depended on various underlying assumptions, and the violation of these assumptions may cause non-negligible bias in the resulting estimates. Pharmacoepidemiologists should select the appropriate self-controlled method based on how well the relevant key assumptions are satisfied with respect to the available data.

Population levels of wellbeing and the association with social capital.

PubMed

Taylor, A W; Kelly, G; Dal Grande, E; Kelly, D; Marin, T; Hey, N; Burke, K J; Licinio, J

2017-07-03

This research investigates wellbeing at the population level across demographic, social and health indicators and assesses the association between wellbeing and social capital. Data from a South Australian monthly chronic disease/risk factor surveillance system of randomly selected adults (mean age 48.7 years; range 16-99) from 2014/5 (n = 5551) were used. Univariable analyses compared wellbeing/social capital indicators, socio-demographic, risk factors and chronic conditions. Multi-nominal logistic regression modelling, adjusting for multiple covariates was used to simultaneously estimate odds ratios for good wellbeing (reference category) versus neither good nor poor, and good wellbeing versus poor wellbeing. 48.6% were male, mean age 48.7 (sd 18.3), 54.3% scored well on all four of the wellbeing indicators, and positive social capital indicators ranged from 93.1% for safety to 50.8% for control over decisions. The higher level of social capital corresponded with the good wellbeing category. Modeling showed higher odds ratios for all social capital variables for the lowest level of wellbeing. These higher odds ratios remained after adjusting for confounders. The relationship between wellbeing, resilience and social capital highlights areas for increased policy focus.

Predictors of back disorder among Almeda textile factory workers, North Ethiopia.

PubMed

Abraha, Teklehaymanot Huluf; Demoz, Asmelash Tekie; Moges, Haimanot Gebrehiwot; Ahmmed, Ansha Nega

2018-05-16

To guide the development of targeted interventions for the prevention of work-related back pain, this manuscript estimates the prevalence of back pain and its association with a variety of risk factors among Almeda textile factory production works from March to April 2015. An institutional-based cross-sectional study was carried out in Almeda textile factory, North Ethiopia. Randomly selected workers were administered a structured questionnaire about their socio-economic status, lifestyle, working conditions, back pain and selected risk factors. The data was entered to Epi Info 3.5.4 version and analyzed using SPSS version 16. Descriptive statistics were done to characterize the study participants. Bivariate and multiple logistic regressions were fitted to control confounding variables. Adjusted odds ratio with 95% confidence intervals was computed. The prevalence of work-related musculoskeletal disorders was 53.1%. Gender, age, years of service, lack of physical activity, unavailability of adjustable chair, work-load and poor light were significantly associated with increased risk of back pain. The high prevalence of work-related back pain disorder implies that; habit of doing physical exercise, availing adjustable chair and light at the working place, are key issues which require specific interventions.

Detecting macroecological patterns in bacterial communities across independent studies of global soils.

PubMed

Ramirez, Kelly S; Knight, Christopher G; de Hollander, Mattias; Brearley, Francis Q; Constantinides, Bede; Cotton, Anne; Creer, Si; Crowther, Thomas W; Davison, John; Delgado-Baquerizo, Manuel; Dorrepaal, Ellen; Elliott, David R; Fox, Graeme; Griffiths, Robert I; Hale, Chris; Hartman, Kyle; Houlden, Ashley; Jones, David L; Krab, Eveline J; Maestre, Fernando T; McGuire, Krista L; Monteux, Sylvain; Orr, Caroline H; van der Putten, Wim H; Roberts, Ian S; Robinson, David A; Rocca, Jennifer D; Rowntree, Jennifer; Schlaeppi, Klaus; Shepherd, Matthew; Singh, Brajesh K; Straathof, Angela L; Bhatnagar, Jennifer M; Thion, Cécile; van der Heijden, Marcel G A; de Vries, Franciska T

2018-02-01

The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential 'indicator' taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.

A qualitative study of medical educators' perspectives on remediation: Adopting a holistic approach to struggling residents.

PubMed

Krzyzaniak, Sara M; Wolf, Stephen J; Byyny, Richard; Barker, Lisa; Kaplan, Bonnie; Wall, Stephen; Guerrasio, Jeannette

2017-09-01

During residency, some trainees require the identification and remediation of deficiencies to achieve the knowledge, skills and attitudes necessary for independent practice. Given the limited published frameworks for remediation, we characterize remediation from the perspective of educators and propose a holistic framework to guide the approach to remediation. We conducted semistructured focus groups to: explore methods for identifying struggling residents; categorize common domains of struggle; describe personal factors that contribute to difficulties; define remediation interventions and understand what constitutes successful completion. Data were analyzed through conventional content analysis. Nineteen physicians across multiple specialties and institutions participated in seven focus groups. Thirteen categories emerged around remediation. Some themes addressed practical components of remediation, while others reflected barriers to the process and the impact of remediation on the resident and program. The themes were used to inform development of a novel holistic framework for remediation. The approach to remediation requires comprehensive identification of individual factors impacting performance. The intervention should not only include a tailored learning plan but also address confounders that impact likelihood of remediation success. Our holistic framework intends to guide educators creating remediation plans to ensure all domains are addressed.

[Gender and age differences in social support and body mass index in adults in Greater Metropolitan Rio de Janeiro, Brazil].

PubMed

França-Santos, Debora; Oliveira, Aldair José de; Salles-Costa, Rosana; Lopes, Claudia de Souza; Sichieri, Rosely

2017-06-05

The objective was to investigate gender and age differences in the association between dimensions of social support and body mass index (BMI) in a sample of 1,465 adults (20 to 59 years) in a population-based study in Duque de Caxias, Rio de Janeiro State, Brazil. Anthropometry was conducted by trained evaluators and social support obtained by the Medical Outcomes Study, adapted and validated for the Brazilian population. The analyses were performed with multiple linear regressions, stratified by gender and age bracket, considering the sample's expansion factor and complex design. Obesity prevalence was 28% in women and 16.2% in men. After adjusting for confounders, a negative association was observed between social support and BMI in men 40-49 years of age, and in emotional support/information (β = -2.04), and positive social interaction (β = -2.40). There was a positive association for social support and BMI in men 50-59 years of age in emotional support/information (β = 1.84). The study indicates that social support can protect against obesity in men in some dimensions and age brackets. However, social support does not appear to be a protective factor in women.

Hospitalizations for Accidents and Induries in the U.S. Navy. IV. A Comparison of Nuclear and Conventionally Powered Surface Ships.

DTIC Science & Technology

1986-04-01

SURFACE SHIPS C. M. BONE J . C. HELMKAMP DTIC REPORT NO. 86-8 IWELECTE "’AUG 2 71986 ~. DistributLlU hti~ NAVAL HEALTH RESEARCH CENTER Q... P.O. BOX 85122...carrier and cruiser personnel comparisons. This risk was 1.5 and 2. J times the risk of hospitalization, respectively, for the same aged personnel...in these two groups, some confounding bias may have occurred. 10 Pr,, ’e ’, j .*-~~’V**, *~*~**** ,’*. ’~ Another confounding factor may stem from duty

The development of a modified spectral ripple test.

PubMed

Aronoff, Justin M; Landsberger, David M

2013-08-01

Poor spectral resolution can be a limiting factor for hearing impaired listeners, particularly for complex listening tasks such as speech understanding in noise. Spectral ripple tests are commonly used to measure spectral resolution, but these tests contain a number of potential confounds that can make interpretation of the results difficult. To measure spectral resolution while avoiding those confounds, a modified spectral ripple test with dynamically changing ripples was created, referred to as the spectral-temporally modulated ripple test (SMRT). This paper describes the SMRT and provides evidence that it is sensitive to changes in spectral resolution.

[Relationship between pre-pregnant body mass index, maternal weight gain and small for gestational age].

PubMed

Peng, Tingting; Yue, Fujuan; Wang, Fang; Feng, Yongliang; Wu, Weiwei; Wang, Suping; Zhang, Yawei; Yang, Hailan

2015-06-01

To investigate the relationship between maternal pre-pregnancy body mass index, weight gain during pregnancy and small for gestational age (SGA) birth so as to provide evidence for the development of comprehensive prevention programs on SGA birth. Between March, 2012 and July, 2014, 4 754 pregnant women were asked to fill in the questionnaires which were collected from the First Affiliated Hospital of Shanxi Medical University. Data related to general demographic characteristics, pregnancy and health status of those pregnant women was collected and maternal pre-pregnancy body mass index and maternal weight gain were calculated. Subjects were divided into different groups before the effect of maternal pre-pregnancy body mass index and weight gain during pregnancy on SGA birth were estimated. The overall incidence of SGA birth was 9.26% (440/4 754). Proportions of SGA birth from pre-pregnant, underweight group, normal weight group, overweight and obese groups were 9.85%, 8.54% and 9.45%, respectively. Results from multi-factor logistic regression analyses showed that after adjusting the confounding factors as age, history on pregnancies etc., women with high pre-pregnancy BMI showed a lower incidence of SGA than those under normal pre-pregnancy BMI (OR = 0.714, 95% CI: 0.535-0.953). Different weight gains during pregnancy were statistically significant (χ(2) = 8.811, P = 0.012). Incidence of SGA birth that was below the recommended range in the 2009 Institute of Medicine Guidelines (12.20%) was higher than those within (9.23%) or beyond (8.45%) the recommended range. Results from the multi-factor logistic regression analyses showed that, after adjusting the confounding factors as age, pregnancy history etc., factor as weight gain below the recommended level could increase the risk of SGA (OR = 1.999, 95% CI: 1.487-2.685). In the underweight, normal weight, overweight or obese groups, with weight gain during pregnancy below the range, the incidence of SGA showed an increase (OR = 2.558, 95% CI: 1.313-4.981, OR = 1.804, 95% CI: 1.258-2.587, OR = 3.108, 95% CI: 1.237-7.811). There was no interaction of addictive or multiplicative models between these two factors under 'interaction analysis'. Women with high pre-pregnancy BMI presented a lower incidence of SGA than those within the normal range. Insufficient weight gain during pregnancy could increase the risk of SGA delivery. These findings called for attention to be paid to the gestational weight gain, in order to decrease the risk of SGA.

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.

Long-Term Neurodevelopmental Outcome after Doxapram for Apnea of Prematurity.

PubMed

Ten Hove, Christine H; Vliegenthart, Roseanne J; Te Pas, Arjan B; Brouwer, Emma; Rijken, Monique; van Wassenaer-Leemhuis, Aleid G; van Kaam, Anton H; Onland, Wes

2016-01-01

Doxapram has been advocated as a treatment for persistent apnea of prematurity (AOP). To evaluate the effect of doxapram on long-term neurodevelopmental outcome in preterm infants as its safety still needs to be established. From a retrospective cohort of preterm infants with a gestational age (GA) <30 weeks and/or a birth weight <1,250 g, born between 2000 and 2010, infants treated with doxapram (n = 142) and a nontreated control group were selected (n = 284). Patient characteristics and clinical and neurodevelopmental outcome data at 24 months' corrected age were collected. Neurodevelopmental delay (ND) was defined as having a Mental or Psychomotor Developmental Index (MDI/PDI) <-1 standard deviation (SD), cerebral palsy, or a hearing or visual impairment. Odds ratios (OR) were calculated using multiple logistic regression analyses adjusting for potential confounders. Infants treated with doxapram had a lower GA compared to controls. The number of infants with a MDI or PDI <-1 SD was not different between the groups. The risk of the combined outcome death or ND was significantly lower in the doxapram group after adjusting for confounding factors (OR = 0.54, 95% CI: 0.37, 0.78). Doxapram-treated infants had a higher risk of bronchopulmonary dysplasia and patent ductus arteriosus, but a lower risk of spontaneous intestinal perforation. All other morbidities were not different between the groups. This study suggests that doxapram is not associated with an increased risk of ND. These findings need to be confirmed or refuted by a large, well-designed, placebo-controlled randomized trial. © 2016 The Author(s) Published by S. Karger AG, Basel.

The Trend-in-trend Research Design for Causal Inference.

PubMed

Ji, Xinyao; Small, Dylan S; Leonard, Charles E; Hennessy, Sean

2017-07-01

Cohort studies can be biased by unmeasured confounding. We propose a hybrid ecologic-epidemiologic design called the trend-in-trend design, which requires a strong time trend in exposure, but is unbiased unless there are unmeasured factors affecting outcome for which there are time trends in prevalence that are correlated with time trends in exposure across strata with different exposure trends. Thus, the conditions under which the trend-in-trend study is biased are a subset of those under which a cohort study is biased. The trend-in-trend design first divides the study population into strata based on the cumulative probability of exposure given covariates, which effectively stratifies on time trend in exposure, provided there is a trend. Next, a covariates-free maximum likelihood model estimates the odds ratio (OR) using data on exposure prevalence and outcome frequency within cumulative probability of exposure strata, across multiple periods. In simulations, the trend-in-trend design produced ORs with negligible bias in the presence of unmeasured confounding. In empiric applications, trend-in-trend reproduced the known positive association between rofecoxib and myocardial infarction (observed OR: 1.2, 95% confidence interval: 1.1, 1.4), and known null associations between rofecoxib and severe hypoglycemia (OR = 1.1 [0.92, 1.3]) and nonvertebral fracture (OR = 0.84 [0.64, 1.1]). The trend-in-trend method may be useful in settings where there is a strong time trend in exposure, such as a newly approved drug or other medical intervention. See video abstract at, http://links.lww.com/EDE/B178.

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

Delayed introduction of solid feeding reduces child overweight and obesity at 10 years.

PubMed

Seach, K A; Dharmage, S C; Lowe, A J; Dixon, J B

2010-10-01

The function that the timing of introduction of solid foods may have in the development of child obesity has not been adequately explored, either as a potential confounder of the relationship between breastfeeding and child obesity, or as an independent modifiable risk factor. To determine the association between infant feeding practices and child overweight/obesity. Six hundred and twenty subjects were recruited antenatally from 1990 to 1994. A total of 18 telephone interviews over the first 2 years of life recorded infant feeding practices. At mean age of 10 years, height and weight were measured for 307 subjects. Multiple logistic regression was used to determine whether infant feeding practices (duration of exclusive and any breastfeeding, and age at introduction of solid foods) were associated with odds of being overweight/obese (internationally age- and sex-standardized body mass index category) at age 10 years, after adjustment for confounders. Delayed introduction of solid foods was associated with reduced odds of being overweight/obese at age 10 years, after controlling for socioeconomic status, parental smoking and childcare attendance (adjusted odds ratio (aOR)=0.903 per week, 95% CI=0.841-0.970, P=0.005). Antenatal parental smoking was associated with overweight/obesity at age 10 years (aOR=3.178, 95% CI=1.643-6.147, P=0.001). Duration of exclusive or any breastfeeding was not associated with the outcome. Delayed introduction of solids is associated with reduced odds of child overweight/obesity. Wider promotion of current infant feeding guidelines could have a significant impact on the rates of child overweight and obesity.

Non-inflammatory causes of emergency consultation in patients with multiple sclerosis.

PubMed

Rodríguez de Antonio, L A; García Castañón, I; Aguilar-Amat Prior, M J; Puertas, I; González Suárez, I; Oreja Guevara, C

2018-05-26

To describe non-relapse-related emergency consultations of patients with multiple sclerosis (MS): causes, difficulties in the diagnosis, clinical characteristics, and treatments administered. We performed a retrospective study of patients who attended a multiple sclerosis day hospital due to suspected relapse and received an alternative diagnosis, over a 2-year period. Demographic data, clinical characteristics, final diagnosis, and treatments administered were evaluated. Patients who were initially diagnosed with pseudo-relapse and ultimately diagnosed with true relapse were evaluated specifically. As an exploratory analysis, patients who consulted with non-inflammatory causes were compared with a randomly selected cohort of patients with true relapses who attended the centre in the same period. The study included 50 patients (33 were women; mean age 41.4±11.7years). Four patients (8%) were initially diagnosed with pseudo-relapse and later diagnosed as having a true relapse. Fever and vertigo were the main confounding factors. The non-inflammatory causes of emergency consultation were: neurological, 43.5% (20 patients); infectious, 15.2% (7); psychiatric, 10.9% (5); vertigo, 8.6% (4); trauma, 10.9% (5); and miscellaneous, 10.9% (5). MS-related symptoms constituted the most frequent cause of non-inflammatory emergency consultations. Close follow-up of relapse and pseudo-relapse is necessary to detect incorrect initial diagnoses, avoid unnecessary treatments, and relieve patients' symptoms. Copyright © 2018 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Physical activity and cognitive function in adults with multiple sclerosis: an integrative review.

PubMed

Morrison, Janet D; Mayer, Lori

2017-09-01

To identify and synthesize the research evidence concerning (1) the relationship between physical activity and cognitive performance in persons with multiple sclerosis (MS) and (2) to review the reported effects of physical activity interventions on neurocognitive performance conducted in this population. Relevant peer-reviewed journal articles were identified by searching PubMed, PsychINFO, and SPORTDiscus through May 2016. Full-text articles meeting the inclusion criteria were evaluated for quality using tools developed by the National Institutes of Health. Studies deemed to be of poor quality were excluded from the review. Nineteen studies meeting the inclusion/exclusion criteria were analyzed. Nine studies reported significant relationships between higher levels of physical activity or cardiorespiratory fitness and measures of cognitive function. Data extracted from 10 physical activity intervention studies reported mixed results on the effectiveness of physical activity to improve selected domains of cognitive function in persons with MS. Although correlational studies provide evidence to support a linkage between physical activity and cognitive function in persons with MS, this linkage is confounded by factors that may have influenced the studies' results. Evidence derived from intervention studies that could support a positive effect of physical activity on cognition in persons with MS is equivocal. Implications for Rehabilitation Physical activity has numerous benefits for persons with multiple sclerosis (MS) including improvements in balance, ambulation, depression, fatigue, and quality of life. Structured physical activity programs may contribute to cognitive function stability or improvement in persons with MS.

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.

Maternal smoking during pregnancy and children's cognitive and physical development: a causal risk factor?

PubMed

Gilman, Stephen E; Gardener, Hannah; Buka, Stephen L

2008-09-01

There remains considerable debate regarding the effects of maternal smoking during pregnancy on children's growth and development. Evidence that exposure to maternal smoking during pregnancy is associated with numerous adverse outcomes is contradicted by research suggesting that these associations are spurious. The authors investigated the relation between maternal smoking during pregnancy and 14 developmental outcomes of children from birth through age 7 years, using data from the Collaborative Perinatal Project (1959-1974; n = 52,919). In addition to adjusting for potential confounders measured contemporaneously with maternal smoking, the authors fitted conditional fixed-effects models among siblings that controlled for unmeasured confounders. Results from the conditional analyses indicated a birth weight difference of -85.63 g associated with smoking of >or=20 cigarettes daily during pregnancy (95% confidence interval: -131.91, -39.34) and 2.73 times' higher odds of being overweight at age 7 years (95% confidence interval: 1.30, 5.71). However, the associations between maternal smoking and 12 other outcomes studied (including Apgar score, intelligence, academic achievement, conduct problems, and asthma) were entirely eliminated after adjustment for measured and unmeasured confounders. The authors conclude that the hypothesized effects of maternal smoking during pregnancy on these outcomes either are not present or are not distinguishable from a broader range of familial factors associated with maternal smoking.

Educational inequality in cardiovascular diseases: a sibling approach.

PubMed

Søndergaard, Grethe; Dalton, Susanne Oksbjerg; Mortensen, Laust Hvas; Osler, Merete

2018-02-01

Educational inequality in diseases in the circulatory system (here termed cardiovascular disease) is well documented but may be confounded by early life factors. The aim of this observational study was to examine whether the associations between education and all cardiovascular diseases, ischaemic heart disease and stroke, respectively, were explained by family factors shared by siblings. The study population included all individuals born in Denmark between 1950 and 1979 who had at least one full sibling born in the same period. Using Cox regression, data were analysed in conventional cohort and within-sibship analyses in which the association was examined within siblings discordant on education. Assuming that attenuation of associations in the within-sibship as compared with the cohort analyses would indicate confounding from factors shared within families. A lower educational status was associated with a higher risk of cardiovascular disease, ischaemic heart disease and stroke. All associations attenuated in the within-sibship analyses, in particular in the analyses on ischaemic heart disease before age 45 years. For instance, in the cohort analyses, the hazard rate of ischaemic heart disease among women less than 45 years who had a primary school education was 94% (hazard ratio 1.94 (1.78-2.12) higher than among those with a vocational education, while it attenuated to 51% (hazard ratio 1.51 (1.34-1.71)) in the within-sibship analysis. Confounding from factors shared by siblings explained the associations between education and the cardiovascular disease outcomes but to varying degrees. This should be taken into account when planning interventions aimed at reducing educational inequalities in the development of cardiovascular disease, ischaemic heart disease and stroke.

Relationships among fitness, obesity, screen time and academic achievement in Japanese adolescents.

PubMed

Morita, Noriteru; Nakajima, Toshihiro; Okita, Koichi; Ishihara, Toru; Sagawa, Masato; Yamatsu, Koji

2016-09-01

Students who study intensively in one of Japan's 'cram schools' and/or spend excess time on electronic devices such as video games are in a sedentary state much of the time, and this may affect their physical fitness. We investigated whether there are relationships among obesity, physical fitness and academic achievement in Japanese students after controlling for socioeconomic and behavioral confounding factors. The data of 315 students (152 females [48%], 163 males [52%]; 12-13yrs old) were analyzed. Academic achievement was assessed by the total grade points on eight school subjects (GP8). Students with a body mass index at or above the 85th percentile of each gender were classified as the overweight/obese group. Physical fitness was evaluated by the total score on eight fitness tests. Socioeconomic and behavioral confounders including the mother's educational background, household income, cram school utilization and time spent on video games/mobile phones were used as covariates. The GP8 of the overweight/obese students was significantly lower than that of the normal weight students (27.2 vs. 29.0 points, respectively). After adjusting for the confounders, the physical fitness score was found to be a significant factor for determinants of GP8 in boys (β=0.324), but not in girls. The obesity status was a factor for GP8 in the girls (β=-0.160) but not in the boys. These results suggest that physical fitness in boys and obesity status in girls could be important factors not only for health status but also for academic achievement, independent of socioeconomic and behavioral backgrounds. Copyright © 2016 Elsevier Inc. All rights reserved.

Decreased pain sensitivity due to trimethylbenzene exposure ...

EPA Pesticide Factsheets

Traditionally, human health risk assessments have relied on qualitative approaches for hazard identification, often using the Hill criteria and weight of evidence determinations to integrate data from multiple studies. Recently, the National Research Council has recommended the development of quantitative approaches for evidence integration, including the application of meta-analyses. The following hazard identification case study applies qualitative as well as meta-analytic approaches to trimethylbenzene (TMB) isomers exposure and the potential neurotoxic effects on pain sensitivity. In the meta-analytic approach, a pooled effect size is calculated, after consideration of multiple confounding factors, in order to determine whether the entire database under consideration indicates that TMBs are likely to be a neurotoxic hazard. The pain sensitivity studies included in the present analyses initially seem discordant in their results: effects on pain sensitivity are seen immediately after termination of exposure, appear to resolve 24 hours after exposure, and then reappear 50 days later following foot-shock. Qualitative consideration of toxicological and toxicokinetic characteristics of the TMB isomers suggests that the observed differences between studies are due to testing time and can be explained through a complete consideration of the underlying biology of the effect and the nervous system as a whole. Meta-analyses and –regressions support this conclus

Systematic evaluation of environmental factors: persistent pollutants and nutrients correlated with serum lipid levels

PubMed Central

Patel, Chirag J; Cullen, Mark R; Ioannidis, John PA; Butte, Atul J

2012-01-01

Background Both genetic and environmental factors contribute to triglyceride, low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) levels. Although genome-wide association studies are currently testing the genetic factors systematically, testing and reporting one or a few factors at a time can lead to fragmented literature for environmental chemical factors. We screened for correlation between environmental factors and lipid levels, utilizing four independent surveys with information on 188 environmental factors from the Centers of Disease Control, National Health and Nutrition Examination Survey, collected between 1999 and 2006. Methods We used linear regression to correlate each environmental chemical factor to triglycerides, LDL-C and HDL-C adjusting for age, age2, sex, ethnicity, socio-economic status and body mass index. Final estimates were adjusted for waist circumference, diabetes status, blood pressure and survey. Multiple comparisons were controlled for by estimating the false discovery rate and significant findings were tentatively validated in an independent survey. Results We identified and validated 29, 9 and 17 environmental factors correlated with triglycerides, LDL-C and HDL-C levels, respectively. Findings include hydrocarbons and nicotine associated with lower HDL-C and vitamin E (γ-tocopherol) associated with unfavourable lipid levels. Higher triglycerides and lower HDL-C were correlated with higher levels of fat-soluble contaminants (e.g. polychlorinated biphenyls and dibenzofurans). Nutrients and vitamin markers (e.g. vitamins B, D and carotenes), were associated with favourable triglyceride and HDL-C levels. Conclusions Our systematic association study has enabled us to postulate about broad environmental correlation to lipid levels. Although subject to confounding and reverse causality bias, these findings merit evaluation in additional cohorts. PMID:22421054

Is cannabis a risk factor for suicide attempts in men and women with psychotic illness?

PubMed

Waterreus, A; Di Prinzio, P; Badcock, J C; Martin-Iverson, M; Jablensky, A; Morgan, V A

2018-05-16

To investigate whether recent cannabis use by men and women with psychotic disorders was associated with increased risk of suicide attempt, and to determine associated factors, stratified by sex. Data from 1065 men and 725 women interviewed in the Australian national survey of psychosis were analysed to model separately, for each sex, the impact of daily, casual or no past-year cannabis use and other risk factors including age, on a past-year suicide attempt. In the past year, 168 (9.4%) participants attempted suicide. Unadjusted analyses showed daily cannabis users of both sexes had significantly increased odds of attempting suicide compared to non-users. After adjusting for confounding factors, this relationship was no longer significant. Depression had the strongest association with attempting suicide for both sexes. Sex differences in other risk factors were observed. In post hoc analysis, daily cannabis use was associated with higher odds of attempting suicide in older men compared to non-users; this was not found in younger men or women. Associations between past-year cannabis use and suicide attempts were confounded by other factors (depression, loneliness, homelessness and hallucinations). The possibility of greater risk of suicidal behaviour with regular cannabis use for older men should be considered.

Coronary Artery Calcification in Japanese Men in Japan and Hawaii

PubMed Central

Abbott, Robert D.; Ueshima, Hirotsugu; Rodriguez, Beatriz L.; Kadowaki, Takashi; Masaki, Kamal H.; Willcox, Bradley J.; Sekikawa, Akira; Kuller, Lewis H.; Edmundowicz, Daniel; Shin, Chol; Kashiwagi, Atsunori; Nakamura, Yasuyuki; El-Saed, Aiman; Okamura, Tomonori; White, Roger; Curb, J. David

2013-01-01

Explanations for the low prevalence of atherosclerosis in Japan versus United States are often confounded with genetic variation. To help remove such confounding, coronary artery calcification (CAC), a marker of subclinical atherosclerosis, was compared between Japanese men in Japan and Japanese men in Hawaii. Findings are based on risk factor and CAC measurements that were made from 2001 to 2005 in 311 men in Japan and 300 men in Hawaii. Men were aged 40 to 50 years and without cardiovascular disease. After age-adjustment, there was a 3-fold excess in the odds of prevalent CAC scores ≥10 in Hawaii versus Japan (relative odds [RO] = 3.2; 95% confidence interval [CI] = 2.1,4.9). While men in Hawaii had a generally poorer risk factor profile, men in Japan were 4-times more likely to smoke cigarettes (49.5 vs. 12.7%, p<0.001). In spite of marked risk factor differences between the samples, none of the risk factors provided an explanation for the low amounts of CAC in Japan. After risk factor adjustment, the RO of CAC scores ≥10 in Hawaii versus Japan was 4.0 (95% CI = 2.2,7.4). Further studies are needed to identify factors that offer protection against atherosclerosis in Japanese men in Japan. PMID:17728270

Microsatellite polymorphisms associated with human behavioural and psychological phenotypes including a gene-environment interaction.

PubMed

Bagshaw, Andrew T M; Horwood, L John; Fergusson, David M; Gemmell, Neil J; Kennedy, Martin A

2017-02-03

The genetic and environmental influences on human personality and behaviour are a complex matter of ongoing debate. Accumulating evidence indicates that short tandem repeats (STRs) in regulatory regions are good candidates to explain heritability not accessed by genome-wide association studies. We tested for associations between the genotypes of four selected repeats and 18 traits relating to personality, behaviour, cognitive ability and mental health in a well-studied longitudinal birth cohort (n = 458-589) using one way analysis of variance. The repeats were a highly conserved poly-AC microsatellite in the upstream promoter region of the T-box brain 1 (TBR1) gene and three previously studied STRs in the activating enhancer-binding protein 2-beta (AP2-β) and androgen receptor (AR) genes. Where significance was found we used multiple regression to assess the influence of confounding factors. Carriers of the shorter, most common, allele of the AR gene's GGN microsatellite polymorphism had fewer anxiety-related symptoms, which was consistent with previous studies, but in our study this was not significant following Bonferroni correction. No associations with two repeats in the AP2-β gene withstood this correction. A novel finding was that carriers of the minor allele of the TBR1 AC microsatellite were at higher risk of conduct problems in childhood at age 7-9 (p = 0.0007, which did pass Bonferroni correction). Including maternal smoking during pregnancy (MSDP) in models controlling for potentially confounding influences showed that an interaction between TBR1 genotype and MSDP was a significant predictor of conduct problems in childhood and adolescence (p < 0.001), and of self-reported criminal behaviour up to age 25 years (p ≤ 0.02). This interaction remained significant after controlling for possible confounders including maternal age at birth, socio-economic status and education, and offspring birth weight. The potential functional importance of the TBR1 gene's promoter microsatellite deserves further investigation. Our results suggest that it participates in a gene-environment interaction with MDSP and antisocial behaviour. However, previous evidence that mothers who smoke during pregnancy carry genes for antisocial behaviour suggests that epistasis may influence the interaction.

Fertility and HIV following universal access to ART in Rwanda: a cross-sectional analysis of Demographic and Health Survey data.

PubMed

Remera, Eric; Boer, Kimberly; Umuhoza, Stella M; Hedt-Gauthier, Bethany L; Thomson, Dana R; Ndimubanzi, Patrick; Kayirangwa, Eugenie; Mutsinzi, Salomon; Bayingana, Alice; Mugwaneza, Placidie; Koama, Jean Baptiste T

2017-03-14

HIV infection is linked to decreased fertility and fertility desires in sub-Saharan Africa due to biological and social factors. We investigate the relationship between HIV infection and fertility or fertility desires in the context of universal access to antiretroviral therapy introduced in 2004 in Rwanda. We used data from 3532 and 4527 women aged 20-49 from the 2005 and 2010 Rwandan Demographic and Health Surveys (RDHS), respectively. The RDHSs included blood-tests for HIV, as well as detailed interviews about fertility, demographic and behavioral outcomes. In both years, multiple logistic regression was used to assess the association between HIV and fertility outcomes within three age categories (20-29, 30-39 and 40-49 years), controlling for confounders and compensating for the complex survey design. In 2010, we did not find a difference in the odds of pregnancy in the last 5 years between HIV-seropositive and HIV-seronegative women after controlling for potential biological and social confounders. Controlling for the same confounders, we found that HIV-seropositive women under age 40 were less likely to desire more children compared to HIV-seronegative women (20-29 years adjusted odds ratio (AOR) = 0.31, 95% CI: 0.17, 0.58; 30-39 years AOR = 0.24, 95% CI: 0.14, 0.43), but no difference was found among women aged 40 or older. No associations between HIV and fertility or fertility desire were found in 2005. These findings suggest no difference in births or current pregnancy among HIV-seropositive and HIV-seronegative women. That in 2010 HIV-seropositive women in their earlier childbearing years desired fewer children than HIV-seronegative women could suggest more women with HIV survived; and stigma, fear of transmitting HIV, or realism about living with HIV and prematurely dying from HIV may affect their desire to have children. These findings emphasize the importance of delivering appropriate information about pregnancy and childbearing to HIV-infected women, enabling women living with HIV to make informed decisions about their reproductive life.

Visual Display Terminal use in Iranian bank tellers: Effects on job stress and insomnia.

PubMed

Giahi, Omid; Shahmoradi, Behzad; Barkhordari, Abdullah; Khoubi, Jamshid

2015-01-01

Visual Display Terminals (VDTs) are equipments in many workplaces which their use may increase the risk of visual, musculoskeletal and mental problems including insomnia. To determine the relationship between duration of daily VDT use and insomnia among the Iranian bank tellers. We randomly selected 382 bank tellers working with VDT. Quality of sleep and stress information were collected by Athens Insomnia Scales (AIS) and Demand-Control Model (DCM) model respectively. Out of 382 participants, 127 (33.2%) had sleep complaints and 255 (66.8%) had no sleep disorders. Moreover, the insomnia symptoms' score were significantly high in the participants having more than 6 hours of daily VDT use after adjusting for multiple confounding factors (P <  0.001). There was no significant relationship between stress and insomnia. It seems that the low levels of stress and job satisfaction reduce the impact of VDT on sleep quality in tellers who worked less than 6 hours per day.

Paleo-drainage basin connectivity predicts evolutionary relationships across three Southeast Asian biodiversity hotspots.

PubMed

de Bruyn, Mark; Rüber, Lukas; Nylinder, Stephan; Stelbrink, Björn; Lovejoy, Nathan R; Lavoué, Sébastien; Tan, Heok Hui; Nugroho, Estu; Wowor, Daisy; Ng, Peter K L; Siti Azizah, M N; Von Rintelen, Thomas; Hall, Robert; Carvalho, Gary R

2013-05-01

Understanding factors driving diversity across biodiversity hotspots is critical for formulating conservation priorities in the face of ongoing and escalating environmental deterioration. While biodiversity hotspots encompass a small fraction of Earth's land surface, more than half the world's plants and two-thirds of terrestrial vertebrate species are endemic to these hotspots. Tropical Southeast (SE) Asia displays extraordinary species richness, encompassing four biodiversity hotspots, though disentangling multiple potential drivers of species richness is confounded by the region's dynamic geological and climatic history. Here, we use multilocus molecular genetic data from dense multispecies sampling of freshwater fishes across three biodiversity hotspots, to test the effect of Quaternary climate change and resulting drainage rearrangements on aquatic faunal diversification. While Cenozoic geological processes have clearly shaped evolutionary history in SE Asian halfbeak fishes, we show that paleo-drainage re-arrangements resulting from Quaternary climate change played a significant role in the spatiotemporal evolution of lowland aquatic taxa, and provide priorities for conservation efforts.

Birth Weight and Social Trust in Adulthood: Evidence for Early Calibration of Social Cognition.

PubMed

Petersen, Michael Bang; Aarøe, Lene

2015-11-01

Social trust forms the fundamental basis for social interaction within societies. Understanding the cognitive architecture of trust and the roots of individual differences in trust is of key importance. We predicted that one of the factors calibrating individual levels of trust is the intrauterine flow of nutrients from mother to child as indexed by birth weight. Birth weight forecasts both the future external environment and the internal condition of the individual in multiple ways relevant for social cognition. Specifically, we predicted that low birth weight is utilized as a forecast of a harsh environment, vulnerable condition, or both and, consequently, reduces social trust. The results of the study reported here are consistent with this prediction. Controlling for many confounds through sibling and panel designs, we found that lower birth weight reduced social trust in adulthood. Furthermore, we obtained tentative evidence that this effect is mitigated if adult environments do not induce stress. © The Author(s) 2015.

Familial Risk Moderates the Association Between Sleep and zBMI in Children

PubMed Central

El-Sheikh, Mona

2013-01-01

Objective A cumulative risk approach was used to examine the moderating effect of familial risk factors on relations between actigraphy-based sleep quantity (minutes) and quality (efficiency) and sex- and age-standardized body mass index (zBMI). Methods The sample included 124 boys and 104 girls with a mean age of 10.41 years (SD = 0.67). Children wore actigraphs for 1 week, and their height and weight were assessed in the lab. Results After controlling for potential confounds, multiple regression analyses indicated that sleep minutes predicted children’s zBMI and that both sleep minutes and efficiency interacted with family risk in the prediction of zBMI. The association between poor sleep and zBMI was especially evident for children exposed to higher levels of family risk. Conclusions Findings suggest that not all children who exhibit poor sleep are at equal risk for higher zBMI and that familial and contextual conditions need to be considered in this link. PMID:23699749

Management of acute attacks of hereditary angioedema: potential role of icatibant.

PubMed

Longhurst, Hilary J

2010-09-07

Icatibant (Firazyr(®)) is a novel subcutaneous treatment recently licensed in the European Union for acute hereditary angioedema. Hereditary angioedema, resulting from inherited partial C1 inhibitor deficiency, is a disabling condition characterized by intermittent episodes of bradykinin-mediated angioedema. Icatibant blocks bradykinin B2 receptors, attenutating the episode. Randomized double-blind, placebo-controlled trials of icatibant, showed significant superiority over oral tranexamic acid in 74 European patients and a trend to improvement in a similar US trial comparing icatibant with placebo in 55 patients. Outcomes for several endpoints did not reach significance in the US trial, perhaps because of low participant numbers and confounding factors: a further trial is planned. Open label studies have shown benefit in multiple treatments for attacks at all sites. Approximately 10% of patients require a second dose for re-emergent symptoms, usually 10 to 27 hours after the initial treatment. Its subcutaneous route of administration, good tolerability and novel mode of action make icatibant a promising addition to the limited repertoire of treatments for hereditary angioedema.

MR imaging evaluation of abdominal pain during pregnancy: appendicitis and other nonobstetric causes.

PubMed

Spalluto, Lucy B; Woodfield, Courtney A; DeBenedectis, Carolynn M; Lazarus, Elizabeth

2012-01-01

Clinical diagnosis of the cause of abdominal pain in a pregnant patient is particularly difficult because of multiple confounding factors related to normal pregnancy. Magnetic resonance (MR) imaging is useful in evaluation of abdominal pain during pregnancy, as it offers the benefit of cross-sectional imaging without ionizing radiation or evidence of harmful effects to the fetus. MR imaging is often performed specifically for diagnosis of possible appendicitis, which is the most common illness necessitating emergency surgery in pregnant patients. However, it is important to look for pathologic processes outside the appendix that may be an alternative source of abdominal pain. Numerous entities other than appendicitis can cause abdominal pain during pregnancy, including processes of gastrointestinal, hepatobiliary, genitourinary, vascular, and gynecologic origin. MR imaging is useful in diagnosing the cause of abdominal pain in a pregnant patient because of its ability to safely demonstrate a wide range of pathologic conditions in the abdomen and pelvis beyond appendicitis. © RSNA, 2012.

Association between borderline dysnatremia and mortality insight into a new data mining approach.

PubMed

Girardeau, Yannick; Jannot, Anne-Sophie; Chatellier, Gilles; Saint-Jean, Olivier

2017-11-22

Even small variations of serum sodium concentration may be associated with mortality. Our objective was to confirm the impact of borderline dysnatremia for patients admitted to hospital on in-hospital mortality using real life care data from our electronic health record (EHR) and a phenome-wide association analysis (PheWAS). Retrospective observational study based on patient data admitted to Hôpital Européen George Pompidou, between 01/01/2008 and 31/06/2014; including 45,834 patients with serum sodium determinations on admission. We analyzed the association between dysnatremia and in-hospital mortality, using a multivariate logistic regression model to adjust for classical potential confounders. We performed a PheWAS to identify new potential confounders. Hyponatremia and hypernatremia were recorded for 12.0% and 1.0% of hospital stays, respectively. Adjusted odds ratios (ORa) for severe, moderate and borderline hyponatremia were 3.44 (95% CI, 2.41-4.86), 2.48 (95% CI, 1.96-3.13) and 1.98 (95% CI, 1.73-2.28), respectively. ORa for severe, moderate and borderline hypernatremia were 4.07 (95% CI, 2.92-5.62), 4.42 (95% CI, 2.04-9.20) and 3.72 (95% CI, 1.53-8.45), respectively. Borderline hyponatremia (ORa = 1.57 95% CI, 1.35-1.81) and borderline hypernatremia (ORa = 3.47 95% CI, 2.43-4.90) were still associated with in-hospital mortality after adjustment for classical and new confounding factors identified through the PheWAS analysis. Borderline dysnatremia on admission are independently associated with a higher risk of in-hospital mortality. By using medical data automatically collected in EHR and a new data mining approach, we identified new potential confounding factors that were highly associated with both mortality and dysnatremia.

A powerful and efficient set test for genetic markers that handles confounders

PubMed Central

Listgarten, Jennifer; Lippert, Christoph; Kang, Eun Yong; Xiang, Jing; Kadie, Carl M.; Heckerman, David

2013-01-01

Motivation: Approaches for testing sets of variants, such as a set of rare or common variants within a gene or pathway, for association with complex traits are important. In particular, set tests allow for aggregation of weak signal within a set, can capture interplay among variants and reduce the burden of multiple hypothesis testing. Until now, these approaches did not address confounding by family relatedness and population structure, a problem that is becoming more important as larger datasets are used to increase power. Results: We introduce a new approach for set tests that handles confounders. Our model is based on the linear mixed model and uses two random effects—one to capture the set association signal and one to capture confounders. We also introduce a computational speedup for two random-effects models that makes this approach feasible even for extremely large cohorts. Using this model with both the likelihood ratio test and score test, we find that the former yields more power while controlling type I error. Application of our approach to richly structured Genetic Analysis Workshop 14 data demonstrates that our method successfully corrects for population structure and family relatedness, whereas application of our method to a 15 000 individual Crohn’s disease case–control cohort demonstrates that it additionally recovers genes not recoverable by univariate analysis. Availability: A Python-based library implementing our approach is available at http://mscompbio.codeplex.com. Contact: jennl@microsoft.com or lippert@microsoft.com or heckerma@microsoft.com Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23599503

Physician trust and depression influence adherence to factor replacement: a single-centre cross-sectional study.

PubMed

Tran, D Q; Barry, V; Antun, A; Ribeiro, M; Stein, S; Kempton, C L

2017-01-01

Poor adherence to factor replacement therapy among patients with haemophilia can lead to joint bleeding and eventual disability. The aim of this study was to determine patient-related characteristics associated with adherence to factor replacement in adults with haemophilia. Adults with haemophilia were recruited to participate in this cross-sectional study. Adherence was measured using either the Validated Hemophilia Regimen Treatment Adherence Scale (VERITAS)-Pro or the VERITAS-PRN questionnaire. Simple and multiple regression analyses that controlled for confounding were performed to determine the association between patient-related characteristics and adherence to factor replacement therapy. Of the 99 subjects enrolled, all were men; 91% had haemophilia A and 78% had severe disease. Age ranged from 18 to 62 years. Most (95%) had functional health literacy; but only 23% were numerate. Mean adherence scores were 45.6 (SD 18) and 51.0 (SD 15) for those on a prophylactic and those on an episodic regimen, respectively, with a lower score indicating better adherence. On multivariable analysis, being on any chronic medication, longer duration followed at our haemophilia treatment centre, higher physician trust and better quality of life were associated with higher adherence. A history of depression was associated with lower adherence. Two potentially modifiable characteristics, physician trust and depression, were identified as motivator and barrier to adherence to factor replacement therapy. Promoting a high level of trust between the patient and the healthcare team as well as identifying and treating depression may impact adherence to factor replacement therapy and accordingly reduce joint destruction. © 2016 John Wiley & Sons Ltd.

Infrared spectroscopic imaging detects chemical modifications in liver fibrosis due to diabetes and disease

PubMed Central

Sreedhar, Hari; Varma, Vishal K.; Gambacorta, Francesca V.; Guzman, Grace; Walsh, Michael J.

2016-01-01

The importance of stroma as a rich diagnostic region in tissue biopsies is growing as there is an increasing understanding that disease processes in multiple organs can affect the composition of adjacent connective tissue regions. This may be especially true in the liver, since this organ’s central metabolic role exposes it to multiple disease processes. We use quantum cascade laser infrared spectroscopic imaging to study changes in the chemical status of hepatocytes and fibrotic regions of liver tissue that result from the progression of liver cirrhosis to hepatocellular carcinoma and the potentially confounding effects of diabetes mellitus. PMID:27375956

Understanding the delayed-keyword effect on metacomprehension accuracy.

PubMed

Thiede, Keith W; Dunlosky, John; Griffin, Thomas D; Wiley, Jennifer

2005-11-01

The typical finding from research on metacomprehension is that accuracy is quite low. However, recent studies have shown robust accuracy improvements when judgments follow certain generation tasks (summarizing or keyword listing) but only when these tasks are performed at a delay rather than immediately after reading (K. W. Thiede & M. C. M. Anderson, 2003; K. W. Thiede, M. C. M. Anderson, & D. Therriault, 2003). The delayed and immediate conditions in these studies confounded the delay between reading and generation tasks with other task lags, including the lag between multiple generation tasks and the lag between generation tasks and judgments. The first 2 experiments disentangle these confounded manipulations and provide clear evidence that the delay between reading and keyword generation is the only lag critical to improving metacomprehension accuracy. The 3rd and 4th experiments show that not all delayed tasks produce improvements and suggest that delayed generative tasks provide necessary diagnostic cues about comprehension for improving metacomprehension accuracy.

Startle reduces recall of a recently learned internal model.

PubMed

Wright, Zachary; Patton, James L; Ravichandran, Venn

2011-01-01

Recent work has shown that preplanned motor programs are released early from subcortical areas by the using a startling acoustic stimulus (SAS). Our question is whether this response might also contain a recently learned internal model, which draws on experience to predict and compensate for expected perturbations in a feedforward manner. Studies of adaptation to robotic forces have shown some evidence of this, but were potentially confounded by cocontraction caused by startle. We performed a new adaptation experiment using a visually distorted field that could not be confounded by cocontraction. We found that in all subjects that exhibited startle, the startle stimulus (1) reduced performance of the recently learned task (2) reduced after-effect magnitudes. Because startle reduced but did not eliminate the recall of learned control, we suggest that multiple neural centers (cortical and subcortical) are involved in such learning and adaptation, which can impact training areas such as piloting, teleoperation, sports, and rehabilitation. © 2011 IEEE

Mediation Analysis: A Practitioner's Guide.

PubMed

VanderWeele, Tyler J

2016-01-01

This article provides an overview of recent developments in mediation analysis, that is, analyses used to assess the relative magnitude of different pathways and mechanisms by which an exposure may affect an outcome. Traditional approaches to mediation in the biomedical and social sciences are described. Attention is given to the confounding assumptions required for a causal interpretation of direct and indirect effect estimates. Methods from the causal inference literature to conduct mediation in the presence of exposure-mediator interactions, binary outcomes, binary mediators, and case-control study designs are presented. Sensitivity analysis techniques for unmeasured confounding and measurement error are introduced. Discussion is given to extensions to time-to-event outcomes and multiple mediators. Further flexible modeling strategies arising from the precise counterfactual definitions of direct and indirect effects are also described. The focus throughout is on methodology that is easily implementable in practice across a broad range of potential applications.

Memory Test Performance on Analogous Verbal and Nonverbal Memory Tests in Patients with Frontotemporal Dementia and Alzheimer's Disease.

PubMed

Baldock, Deanna; Miller, Justin B; Leger, Gabriel C; Banks, Sarah Jane

2016-01-01

Patients with frontotemporal dementia (FTD) typically have initial deficits in language or changes in personality, while the defining characteristic of Alzheimer's disease (AD) is memory impairment. Neuropsychological findings in the two diseases tend to differ, but can be confounded by verbal impairment in FTD impacting performance on memory tests in these patients. Twenty-seven patients with FTD and 102 patients with AD underwent a neuropsychological assessment before diagnosis. By utilizing analogous versions of a verbal and nonverbal memory test, we demonstrated differences in these two modalities between AD and FTD. Better differentiation between AD and FTD is found in a nonverbal memory test, possibly because it eliminates the confounding variable of language deficits found in patients with FTD. These results highlight the importance of nonverbal learning tests with multiple learning trials in diagnostic testing.

GABA and glutamate levels correlate with MTR and clinical disability: Insights from multiple sclerosis.

PubMed

Nantes, Julia C; Proulx, Sébastien; Zhong, Jidan; Holmes, Scott A; Narayanan, Sridar; Brown, Robert A; Hoge, Richard D; Koski, Lisa

2017-08-15

Converging areas of research have implicated glutamate and γ-aminobutyric acid (GABA) as key players in neuronal signalling and other central functions. Further research is needed, however, to identify microstructural and behavioral links to regional variability in levels of these neurometabolites, particularly in the presence of demyelinating disease. Thus, we sought to investigate the extent to which regional glutamate and GABA levels are related to a neuroimaging marker of microstructural damage and to motor and cognitive performance. Twenty-one healthy volunteers and 47 people with multiple sclerosis (all right-handed) participated in this study. Motor and cognitive abilities were assessed with standard tests used in the study of multiple sclerosis. Proton magnetic resonance spectroscopy data were acquired from sensorimotor and parietal regions of the brains' left cerebral hemisphere using a MEGA-PRESS sequence. Our analysis protocol for the spectroscopy data was designed to account for confounding factors that could contaminate the measurement of neurometabolite levels due to disease, such as the macromolecule signal, partial volume effects, and relaxation effects. Glutamate levels in both regions of interest were lower in people with multiple sclerosis. In the sensorimotor (though not the parietal) region, GABA concentration was higher in the multiple sclerosis group compared to controls. Lower magnetization transfer ratio within grey and white matter regions from which spectroscopy data were acquired was linked to neurometabolite levels. When adjusting for age, normalized brain volume, MTR, total N-acetylaspartate level, and glutamate level, significant relationships were found between lower sensorimotor GABA level and worse performance on several tests, including one of upper limb motor function. This work highlights important methodological considerations relevant to analysis of spectroscopy data, particularly in the afflicted human brain. These findings support that regional neurotransmitter levels are linked to local microstructural integrity and specific behavioral abilities that can be affected in diseases such as multiple sclerosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Social stressors and air pollution across New York City communities: a spatial approach for assessing correlations among multiple exposures.

PubMed

Shmool, Jessie L C; Kubzansky, Laura D; Newman, Ogonnaya Dotson; Spengler, John; Shepard, Peggy; Clougherty, Jane E

2014-11-06

Recent toxicological and epidemiological evidence suggests that chronic psychosocial stress may modify pollution effects on health. Thus, there is increasing interest in refined methods for assessing and incorporating non-chemical exposures, including social stressors, into environmental health research, towards identifying whether and how psychosocial stress interacts with chemical exposures to influence health and health disparities. We present a flexible, GIS-based approach for examining spatial patterns within and among a range of social stressors, and their spatial relationships with air pollution, across New York City, towards understanding their combined effects on health. We identified a wide suite of administrative indicators of community-level social stressors (2008-2010), and applied simultaneous autoregressive models and factor analysis to characterize spatial correlations among social stressors, and between social stressors and air pollutants, using New York City Community Air Survey (NYCCAS) data (2008-2009). Finally, we provide an exploratory ecologic analysis evaluating possible modification of the relationship between nitrogen dioxide (NO2) and childhood asthma Emergency Department (ED) visit rates by social stressors, to demonstrate how the methods used to assess stressor exposure (and/or consequent psychosocial stress) may alter model results. Administrative indicators of a range of social stressors (e.g., high crime rate, residential crowding rate) were not consistently correlated (rho = - 0.44 to 0.89), nor were they consistently correlated with indicators of socioeconomic position (rho = - 0.54 to 0.89). Factor analysis using 26 stressor indicators suggested geographically distinct patterns of social stressors, characterized by three factors: violent crime and physical disorder, crowding and poor access to resources, and noise disruption and property crimes. In an exploratory ecologic analysis, these factors were differentially associated with area-average NO2 and childhood asthma ED visits. For example, only the 'violent crime and disorder' factor was significantly associated with asthma ED visits, and only the 'crowding and resource access' factor modified the association between area-level NO2 and asthma ED visits. This spatial approach enabled quantification of complex spatial patterning and confounding between chemical and non-chemical exposures, and can inform study design for epidemiological studies of separate and combined effects of multiple urban exposures.

The Confounding Effects of Ability, Item Difficulty, and Content Balance within Multiple Dimensions on the Estimation of Unidimensional Thetas

ERIC Educational Resources Information Center

Matlock, Ki Lynn

2013-01-01

When test forms that have equal total test difficulty and number of items vary in difficulty and length within sub-content areas, an examinee's estimated score may vary across equivalent forms, depending on how well his or her true ability in each sub-content area aligns with the difficulty of items and number of items within these areas.…

The use of aquatic bioconcentration factors in ecological risk assessments: Confounding issues, laboratory v/s modeled results

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

Brandt, C.; Blanton, M.L.; Dirkes, R.

1995-12-31

Bioconcentration in aquatic systems is generally taken to refer to contaminant uptake through non-ingestion pathways (i.e., dermal and respiration uptake). Ecological risk assessments performed on aquatic systems often rely on published data on bioconcentration factors to calibrate models of exposure. However, many published BCFs, especially those from in situ studies, are confounded by uptake from ingestion of prey. As part of exposure assessment and risk analysis of the Columbia River`s Hanford Reach, the authors tested a methodology to estimate radionuclide BCFs for several aquatic species in the Hanford Reach of the Columbia River. The iterative methodology solves for BCFs frommore » known body burdens and environmental media concentrations. This paper provides BCF methodology description comparisons of BCF from literature and modeled values and how they were used in the exposure assessment and risk analysis of the Columbia River`s Hanford Reach.« less

A Vision for an International Multi-Sensor Snow Observing Mission

NASA Technical Reports Server (NTRS)

Kim, Edward

2015-01-01

Discussions within the international snow remote sensing community over the past two years have led to encouraging consensus regarding the broad outlines of a dedicated snow observing mission. The primary consensus - that since no single sensor type is satisfactory across all snow types and across all confounding factors, a multi-sensor approach is required - naturally leads to questions about the exact mix of sensors, required accuracies, and so on. In short, the natural next step is to collect such multi-sensor snow observations (with detailed ground truth) to enable trade studies of various possible mission concepts. Such trade studies must assess the strengths and limitations of heritage as well as newer measurement techniques with an eye toward natural sensitivity to desired parameters such as snow depth and/or snow water equivalent (SWE) in spite of confounding factors like clouds, lack of solar illumination, forest cover, and topography, measurement accuracy, temporal and spatial coverage, technological maturity, and cost.

Why Assembling Plant Genome Sequences Is So Challenging

PubMed Central

Claros, Manuel Gonzalo; Bautista, Rocío; Guerrero-Fernández, Darío; Benzerki, Hicham; Seoane, Pedro; Fernández-Pozo, Noé

2012-01-01

In spite of the biological and economic importance of plants, relatively few plant species have been sequenced. Only the genome sequence of plants with relatively small genomes, most of them angiosperms, in particular eudicots, has been determined. The arrival of next-generation sequencing technologies has allowed the rapid and efficient development of new genomic resources for non-model or orphan plant species. But the sequencing pace of plants is far from that of animals and microorganisms. This review focuses on the typical challenges of plant genomes that can explain why plant genomics is less developed than animal genomics. Explanations about the impact of some confounding factors emerging from the nature of plant genomes are given. As a result of these challenges and confounding factors, the correct assembly and annotation of plant genomes is hindered, genome drafts are produced, and advances in plant genomics are delayed. PMID:24832233

Analyzing self-controlled case series data when case confirmation rates are estimated from an internal validation sample.

PubMed

Xu, Stanley; Clarke, Christina L; Newcomer, Sophia R; Daley, Matthew F; Glanz, Jason M

2018-05-16

Vaccine safety studies are often electronic health record (EHR)-based observational studies. These studies often face significant methodological challenges, including confounding and misclassification of adverse event. Vaccine safety researchers use self-controlled case series (SCCS) study design to handle confounding effect and employ medical chart review to ascertain cases that are identified using EHR data. However, for common adverse events, limited resources often make it impossible to adjudicate all adverse events observed in electronic data. In this paper, we considered four approaches for analyzing SCCS data with confirmation rates estimated from an internal validation sample: (1) observed cases, (2) confirmed cases only, (3) known confirmation rate, and (4) multiple imputation (MI). We conducted a simulation study to evaluate these four approaches using type I error rates, percent bias, and empirical power. Our simulation results suggest that when misclassification of adverse events is present, approaches such as observed cases, confirmed case only, and known confirmation rate may inflate the type I error, yield biased point estimates, and affect statistical power. The multiple imputation approach considers the uncertainty of estimated confirmation rates from an internal validation sample, yields a proper type I error rate, largely unbiased point estimate, proper variance estimate, and statistical power. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Squeezing observational data for better causal inference: Methods and examples for prevention research.

PubMed

Garcia-Huidobro, Diego; Michael Oakes, J

2017-04-01

Randomised controlled trials (RCTs) are typically viewed as the gold standard for causal inference. This is because effects of interest can be identified with the fewest assumptions, especially imbalance in background characteristics. Yet because conducting RCTs are expensive, time consuming and sometimes unethical, observational studies are frequently used to study causal associations. In these studies, imbalance, or confounding, is usually controlled with multiple regression, which entails strong assumptions. The purpose of this manuscript is to describe strengths and weaknesses of several methods to control for confounding in observational studies, and to demonstrate their use in cross-sectional dataset that use patient registration data from the Juan Pablo II Primary Care Clinic in La Pintana-Chile. The dataset contains responses from 5855 families who provided complete information on family socio-demographics, family functioning and health problems among their family members. We employ regression adjustment, stratification, restriction, matching, propensity score matching, standardisation and inverse probability weighting to illustrate the approaches to better causal inference in non-experimental data and compare results. By applying study design and data analysis techniques that control for confounding in different ways than regression adjustment, researchers may strengthen the scientific relevance of observational studies. © 2016 International Union of Psychological Science.

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

Association between obesity and glomerular hyperfiltration: the confounding effect of smoking and sodium and protein intakes.

PubMed

Ogna, Adam; Forni Ogna, Valentina; Bochud, Murielle; Guessous, Idris; Paccaud, Fred; Burnier, Michel; Wuerzner, Gregoire

2016-04-01

Glomerular hyperfiltration has been suggested as a possible mechanism linking obesity and chronic kidney disease (CKD), independently of classical risk factors. We explored the association of overweight and obesity with glomerular hyperfiltration in a large sample of the Swiss adult population, accounting for several confounders including dietary factors. Data from a 2010 to 2012 cross-sectional population-based survey in Switzerland were used. Creatinine clearance (CrCl) was determined from 24-h urine collection; CrCl > 140 ml/min was used to define glomerular hyperfiltration. Participants were categorized into lean (<25 kg/m(2)), overweight (25-29.9 kg/m(2)) and obese (≥30 kg/m(2)) according to body mass index (BMI). A total of 1339 participants were included in the analysis [median (IQR) age 49.4 (34.3-63.5) years, 48.9 % men]. The prevalences of overweight and obesity were 32.2 and 14.2 %, respectively. Median CrCl was 102[84-121] ml/min in lean, 110 [87-136] ml/min in overweight and 124 [97-150] ml/min in obese participants (p < 0.001). The prevalence of glomerular hyperfiltration increased across BMI categories (10.4, 20.8 and 34.7 %, respectively; p < 0.001). This positive association remained significant after adjusting for age, sex, hypertension, diabetes, smoking and dietary factors (sodium and protein intakes): odds ratio [95 %CI] 2.39 [1.52-3.76] (p < 0.001) for overweight versus lean and 4.10[2.31-7.27] (p < 0.001) for obesity versus lean. BMI categories and glomerular hyperfiltration are positively associated, independently of other known CKD risk factors and dietary confounders, suggesting that glomerular hyperfiltration may represent an early renal phenotype in obesity. Our observations confirm the significant association of glomerular hyperfiltration with sodium and protein intakes and identify sodium intake as an important modifying factor of the association between hyperfiltration and obesity.

Psychosocial working conditions, occupational groups, and risk of disability pension due to mental diagnoses: a cohort study of 43,000 Swedish twins.

PubMed

Samuelsson, Åsa; Ropponen, Annina; Alexanderson, Kristina; Svedberg, Pia

2013-07-01

The aim of this study was to investigate associations between psychosocial working conditions, occupational groups defined by sector, and disability pension (DP) with mental diagnoses while accounting for familial confounding. A prospective population-based cohort study was conducted, including all Swedish twins who, in January 1993, were living and working in Sweden and not on old-age pension or DP (N=42 715). The twins were followed from 1993-2008 regarding DP. Data on DP, exposures, and covariates were obtained from national registries. Cox proportional hazards regression models with hazard ratios (HR) and 95% confidence intervals (95% CI) were constructed for the whole cohort, and for discordant twin pairs. The associations for the whole cohort between DP with mental diagnoses and (i) job demands (HR 1.23, 95% CI 1.06-1.43), (ii) job control (HR 0.91, 95% CI 0.83-0.99), (iii) healthcare and social work (HR 1.41, 95% CI 1.04-1.92), and (iv) service and military work (HR 2.07, 95% CI 1.37-3.14) remained after accounting for possible confounders, including familial factors, while the associations between DP and (i) social support, (ii) type of jobs, and (iii) some of the occupational groups were attenuated, becoming non-significant. In the discordant twin pair analyses, commercial work was significantly associated with lower risk of DP (HR 0.55, 95% CI 0.32-0.95). One unit increase in job demands and working in the occupational groups healthcare and social work or service and military work seem to be risk factors of DP with mental diagnoses, independent from various background factors including familial ones. However, one unit increase in job control or working in commercial work seem to be protective factors of such DP, accounting for confounding factors of this study.

The evolution of computed tomography from organ-selective to whole-body scanning in managing unconscious patients with multiple trauma

PubMed Central

Hong, Zhi-Jie; Chen, Cheng-Jueng; Yu, Jyh-Cherng; Chan, De-Chuan; Chou, Yu-Ching; Liang, Chia-Ming; Hsu, Sheng-Der

2016-01-01

Abstract We aimed to evaluate the benefit of whole-body computed tomography (WBCT) scanning for unconscious adult patients suffering from high-energy multiple trauma compared with the conventional stepwise approach of organ-selective CT. Totally, 144 unconscious patients with high-energy multiple trauma from single level I trauma center in North Taiwan were enrolled from January 2009 to December 2013. All patients were managed by a well-trained trauma team and were suitable for CT examination. The enrolled patients are all transferred directly from the scene of an accident, not from other medical institutions with a definitive diagnosis. The scanning regions of WBCT include head, neck, chest, abdomen, and pelvis. We analyzed differences between non-WBCT and WBCT groups, including gender, age, hospital stay, Injury Severity Score, Glasgow Coma Scale, Revised Trauma Score, time in emergency department (ED), medical cost, and survival outcome. Fifty-five patients received the conventional approach for treating trauma, and 89 patients received immediate WBCT scanning after an initial examination. Patients’ time in ED was significantly shorter in the WBCT group in comparison with the non-WBCT group (158.62 ± 80.13 vs 216.56 ± 168.32 min, P = 0.02). After adjusting for all possible confounding factors, we also found that survival outcome of the WBCT group was better than that of the non-WBCT group (odds ratio: 0.21, 95% confidence interval: 0.06–0.75, P = 0.016). Early performing WBCT during initial trauma management is a better approach for treating unconscious patients with high-energy multiple trauma. PMID:27631215

The evolution of computed tomography from organ-selective to whole-body scanning in managing unconscious patients with multiple trauma: A retrospective cohort study.

PubMed

Hong, Zhi-Jie; Chen, Cheng-Jueng; Yu, Jyh-Cherng; Chan, De-Chuan; Chou, Yu-Ching; Liang, Chia-Ming; Hsu, Sheng-Der

2016-09-01

We aimed to evaluate the benefit of whole-body computed tomography (WBCT) scanning for unconscious adult patients suffering from high-energy multiple trauma compared with the conventional stepwise approach of organ-selective CT.Totally, 144 unconscious patients with high-energy multiple trauma from single level I trauma center in North Taiwan were enrolled from January 2009 to December 2013. All patients were managed by a well-trained trauma team and were suitable for CT examination. The enrolled patients are all transferred directly from the scene of an accident, not from other medical institutions with a definitive diagnosis. The scanning regions of WBCT include head, neck, chest, abdomen, and pelvis. We analyzed differences between non-WBCT and WBCT groups, including gender, age, hospital stay, Injury Severity Score, Glasgow Coma Scale, Revised Trauma Score, time in emergency department (ED), medical cost, and survival outcome.Fifty-five patients received the conventional approach for treating trauma, and 89 patients received immediate WBCT scanning after an initial examination. Patients' time in ED was significantly shorter in the WBCT group in comparison with the non-WBCT group (158.62 ± 80.13 vs 216.56 ± 168.32 min, P = 0.02). After adjusting for all possible confounding factors, we also found that survival outcome of the WBCT group was better than that of the non-WBCT group (odds ratio: 0.21, 95% confidence interval: 0.06-0.75, P = 0.016).Early performing WBCT during initial trauma management is a better approach for treating unconscious patients with high-energy multiple trauma.

Examining confounding by diet in the association between perfluoroalkyl acids and serum cholesterol in pregnancy

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

Skuladottir, Margret; Ramel, Alfons; Unit for Nutrition Research, Landspitali National University Hospital, Reykjavik

Background: Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have consistently been associated with higher cholesterol levels in cross sectional studies. Concerns have, however, been raised about potential confounding by diet and clinical relevance. Objective: To examine the association between concentrations of PFOS and PFOA and total cholesterol in serum during pregnancy taking into considerations confounding by diet. Methods: 854 Danish women who gave birth in 1988–89 and provided a blood sample and reported their diet in week 30 of gestation. Results: Mean serum PFOS, PFOA and total cholesterol concentrations were 22.3 ng/mL, 4.1 ng/mL and 7.3 mmol/L, respectively. Maternal dietmore » was a significant predictor of serum PFOS and PFOA concentrations. In particular intake of meat and meat products was positively associated while intake of vegetables was inversely associated (P for trend <0.01) with relative difference between the highest and lowest quartile in PFOS and PFOA concentrations ranging between 6% and 25% of mean values. After adjustment for dietary factors both PFOA and PFOS were positively and similarly associated with serum cholesterol (P for trend ≤0.01). For example, the mean increase in serum cholesterol was 0.39 mmol/L (95%CI: 0.09, 0.68) when comparing women in the highest to lowest quintile of PFOA concentrations. In comparison the mean increase in serum cholesterol was 0.61 mmol/L (95%CI: 0.17, 1.05) when comparing women in the highest to lowest quintile of saturated fat intake. Conclusion: In this study associations between PFOS and PFOA with serum cholesterol appeared unrelated to dietary intake and were similar in magnitude as the associations between saturated fat intake and serum cholesterol. - Highlights: • PFOS and PFOA have consistently been linked with raised serum cholesterol • Clinical relevance remains uncertain and confounding by diet has been suggested • The aim of this study was to address these issues in a cohort of 854 pregnant women • With detailed dietary information we found no indication of such confounding • As predictors cholesterol PFOSA and PFOA were similar to other known risk factors.« less

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.

Statin adherence and risk of acute cardiovascular events among women: a cohort study accounting for time-dependent confounding affected by previous adherence.

PubMed

Lavikainen, Piia; Helin-Salmivaara, Arja; Eerola, Mervi; Fang, Gang; Hartikainen, Juha; Huupponen, Risto; Korhonen, Maarit Jaana

2016-06-03

Previous studies on the effect of statin adherence on cardiovascular events in the primary prevention of cardiovascular disease have adjusted for time-dependent confounding, but potentially introduced bias into their estimates as adherence and confounders were measured simultaneously. We aimed to evaluate the effect when accounting for time-dependent confounding affected by previous adherence as well as time sequence between factors. Retrospective cohort study. Finnish healthcare registers. Women aged 45-64 years initiating statin use for primary prevention of cardiovascular disease in 2001-2004 (n=42 807). Acute cardiovascular event defined as a composite of acute coronary syndrome and acute ischaemic stroke was our primary outcome. Low-energy fractures were used as a negative control outcome to evaluate the healthy-adherer effect. During the 3-year follow-up, 474 women experienced the primary outcome event and 557 suffered a low-energy fracture. The causal HR estimated with marginal structural model for acute cardiovascular events for all the women who remained adherent (proportion of days covered ≥80%) to statin therapy during the previous adherence assessment year was 0.78 (95% CI: 0.65 to 0.94) when compared with everybody remaining non-adherent (proportion of days covered <80%). The result was robust against alternative model specifications. Statin adherers had a potentially reduced risk of experiencing low-energy fractures compared with non-adherers (HR 0.90, 95% CI 0.76 to 1.07). Our study, which took into account the time dependence of adherence and confounders, as well as temporal order between these factors, is support for the concept that adherence to statins in women in primary prevention decreases the risk of acute cardiovascular events by about one-fifth in comparison to non-adherence. However, part of the observed effect of statin adherence on acute cardiovascular events may be due to the healthy-adherer effect. 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/

Occupational exposure and ovarian cancer risk.

PubMed

Le, Nhu D; Leung, Andy; Brooks-Wilson, Angela; Gallagher, Richard P; Swenerton, Kenneth D; Demers, Paul A; Cook, Linda S

2014-07-01

Relatively little work has been done concerning occupational risk factors in ovarian cancer. Although studies conducted in occupational settings have reported positive associations, their usefulness is generally limited by the lack of information on important confounders. In a population-based case-control study, we assessed risk for developing epithelial ovarian cancer (EOC) associated with occupational exposure while accounting for important confounders. Participants were identified through provincial population-based registries. Lifetime occupational history and information on potential confounding factors were obtained through a self-administered questionnaire. Unconditional logistic regression and the likelihood ratio test were used to assess EOC risk with each occupation (or industry), relative to all other occupations (or industries), adjusting for potential confounders including body mass index, oral contraceptive use, menopausal hormone therapy, parity, age at first childbirth, age at menarche, age at menopause, family history of breast and ovarian cancer in mother and sister(s), tubal ligation, partial oophorectomy, and hysterectomy. Occupations and industries were coded according to the Canadian Standard Occupational Classification (SOC) and Standard Industrial Classification (SIC). Significant excess risk was observed for several groups of teaching occupations, including SOC 27, teaching and related (adjusted OR 1.77, 95% CI 1.15-2.81) and SOC 279, other teaching and related (adjusted OR 3.11, 95% CI 1.35-8.49). Significant excess was also seen for a four-digit occupational group SOC 4131, bookkeepers and accounting clerks (adjusted OR 2.80, 95% CI 1.30-6.80). Industrial sub-groups showing significant excess risk included SIC 65, other retail stores (adjusted OR 2.19, 95 % CI 1.16-4.38); SIC 85, educational service (adjusted OR 1.45, 95% CI 1.00-2.13); and SIC 863, non-institutional health services (adjusted OR 2.54, 95% CI 1.13-6.52). Our study found an elevated EOC risk for teaching occupations and is the first study to observe such an increased risk after adjustment for potential confounders. Further studies with more detailed assessment of the work environment and unique lifestyle characteristics may be fruitful in elucidating this etiology.

Childhood Medical and Behavioral Consequences of Maternal Cocaine Use1

PubMed Central

Singer, Lynn; Farkas, Kathleen; Kliegman, Robert

2014-01-01

Reviewed available studies of the impact of fetal cocaine exposure on child medical and developmental outcome, as well as the current status of clinical psychological interventions and research strategies. Current studies are inconclusive but suggest that prenatal exposure to crack-cocaine can have significant effects on the growth and neurological development of the infant, with the potential of later learning and behavioral disabilities. Social-environmental correlates of maternal cocaine use are confounding factors with known negative effects on child outcome. Large, population-based studies using multivariate analyses are needed to determine the independent effects of cocaine on child outcome relative to other confounding variables. PMID:1382125

Pre-study feasibility and identifying sensitivity analyses for protocol pre-specification in comparative effectiveness research.

PubMed

Girman, Cynthia J; Faries, Douglas; Ryan, Patrick; Rotelli, Matt; Belger, Mark; Binkowitz, Bruce; O'Neill, Robert

2014-05-01

The use of healthcare databases for comparative effectiveness research (CER) is increasing exponentially despite its challenges. Researchers must understand their data source and whether outcomes, exposures and confounding factors are captured sufficiently to address the research question. They must also assess whether bias and confounding can be adequately minimized. Many study design characteristics may impact on the results; however, minimal if any sensitivity analyses are typically conducted, and those performed are post hoc. We propose pre-study steps for CER feasibility assessment and to identify sensitivity analyses that might be most important to pre-specify to help ensure that CER produces valid interpretable results.

Effectiveness of electronic stability control on single-vehicle accidents.

PubMed

Lyckegaard, Allan; Hels, Tove; Bernhoft, Inger Marie

2015-01-01

This study aims at evaluating the effectiveness of electronic stability control (ESC) on single-vehicle injury accidents while controlling for a number of confounders influencing the accident risk. Using police-registered injury accidents from 2004 to 2011 in Denmark with cars manufactured in the period 1998 to 2011 and the principle of induced exposure, 2 measures of the effectiveness of ESC were calculated: The crude odds ratio and the adjusted odds ratio, the latter by means of logistic regression. The logistic regression controlled for a number of confounding factors, of which the following were significant. For the driver: Age, gender, driving experience, valid driving license, and seat belt use. For the vehicle: Year of registration, weight, and ESC. For the accident surroundings: Visibility, light, and location. Finally, for the road: Speed limit, surface, and section characteristics. The present study calculated the crude odds ratio for ESC-equipped cars of getting in a single-vehicle injury accident as 0.40 (95% confidence interval [CI], 0.34-0.47) and the adjusted odds ratio as 0.69 (95% CI, 0.54-0.88). No difference was found in the effectiveness of ESC across the injury severity categories (slight, severe, and fatal). In line with previous results, this study concludes that ESC reduces the risk for single-vehicle injury accidents by 31% when controlling for various confounding factors related to the driver, the car, and the accident surroundings. Furthermore, it is concluded that it is important to control for human factors (at a minimum age and gender) in analyses where evaluations of this type are performed.

Multiple large solar lentigos on the upper back as clinical markers of past severe sunburn: a case-control study.

PubMed

Derancourt, C; Bourdon-Lanoy, E; Grob, J-J; Guillaume, J-C; Bernard, P; Bastuji-Garin, S

2007-01-01

Multiple solar lentigos commonly seen on the upper back and shoulders of adults are classically considered as a sign of photodamage, although epidemiological studies are scarce. To assess whether these lesions are clinical markers of past severe sunburn. A case-control study in two outpatient dermatology clinics in French university hospitals. Past episodes of moderate and severe sunburn were compared between 145 adult patients with multiple solar lentigos on the upper back and 145 matched controls. In multivariate analysis adjusted for potential confounders, recalled episodes of sunburn during childhood, adolescence and adulthood were independently associated with the presence of multiple solar lentigos (adjusted odds ratios, 95% confidence intervals: 2.3 (1.1-5.2) and 28.1 (10.4-75.6) for moderate and severe sunburn, respectively). Multiple solar lentigos on the upper back and shoulders of adults are potential clinical markers of past severe sunburn which may thus be used to identify a population at higher risk of developing cutaneous malignant melanoma.

Approaches for Strengthening Causal Inference Regarding Prenatal Risk Factors for Childhood Behavioural and Psychiatric Disorders

ERIC Educational Resources Information Center

Lewis, Sarah J.; Relton, Caroline; Zammit, Stanley; Smith, George Davey

2013-01-01

Background: The risk of childhood behavioural and psychiatric diseases could be substantially reduced if modifiable risk factors for these disorders were identified. The critical period for many of these exposures is likely to be in utero as this is the time when brain development is most rapid. However, due to confounding and other limitations of…

Unraveling the Effect of Genes and Environment in the Transmission of Parental Antisocial Behavior to Children's Conduct Disturbance, Depression and Hyperactivity

ERIC Educational Resources Information Center

Silberg, Judy L.; Maes, Hermine; Eaves, Lindon J.

2012-01-01

Background: A critical issue in devising effective interventions for the treatment of children's behavioral and emotional problems identifying genuine family environmental factors that place children at risk. In most twin and family studies, environmental factors are confounded with both direct genetic risk from parents and the indirect effect of…

Physical Fitness Measures as Potential Markers of Low Cognitive Function in Japanese Community-Dwelling Older Adults without Apparent Cognitive Problems.

PubMed

Narazaki, Kenji; Matsuo, Eri; Honda, Takanori; Nofuji, Yu; Yonemoto, Koji; Kumagai, Shuzo

2014-09-01

Detecting signs of cognitive impairment as early as possible is one of the most urgent challenges in preventive care of dementia. It has still been unclear whether physical fitness measures can serve as markers of low cognitive function, a sign of cognitive impairment, in older people free from dementia. The aim of the present study was to examine an association between each of five physical fitness measures and global cognition in Japanese community-dwelling older adults without apparent cognitive problems. The baseline research of the Sasaguri Genkimon Study was conducted from May to August 2011 in Sasaguri town, Fukuoka, Japan. Of the 2,629 baseline subjects who were aged 65 years or older and not certified as individuals requiring nursing care by the town, 1,552 participants without apparent cognitive problems (Mini-Mental State Examination score ≥24) were involved in the present study (59.0% of the baseline subjects, median age: 72 years, men: 40.1%). Global cognitive function was measured by the Japanese version of the Montreal Cognitive Assessment. Handgrip strength, leg strength, sit-to-stand rate, gait speed, and one-leg stand time were examined as physical fitness measures. In multiple linear regression analyses, each of the five physical fitness measures was positively associated with the Montreal Cognitive Assessment score after adjusting for age and sex (p < 0.001). These associations were preserved after additional adjustment for years of formal education, body mass index, and other confounding factors (p < 0.001). The present study first demonstrated the associations between multiple aspects of physical fitness and global cognitive function in Japanese community-dwelling older people without apparent cognitive problems. These results suggest that each of the physical fitness measures has a potential as a single marker of low cognitive function in older populations free from dementia and thereby can be useful in community-based preventive care of dementia. Key pointsThere is a great need for identifying lifestyle-related markers which help detect subtle cognitive impairment in the preclinical or earlier phase of dementia.In the present study, each of the five physical fitness measures employed was linearly and positively associated with the Montreal Cognitive Assessment score in the present older adults without apparent cognitive problems, after adjusting for age, sex, education, body mass index, and other confounding factors.The results suggest the potential of each physical fitness measure as a single lifestyle-related marker of low cognitive function in the population, which can be useful in community-based preventive care of dementia.

The association between exposure to environmental factors and the occurrence of attention-deficit/hyperactivity disorder (ADHD). A population-based retrospective cohort study.

PubMed

Saez, Marc; Barceló, Maria A; Farrerons, Mònica; López-Casasnovas, Guillem

2018-06-08

A number of factors contribute to attention deficit hyperactivity disorder (ADHD) and although they are not fully known, the occurrence of ADHD seems to be a consequence of an interaction between multiple genetic and environmental factors. However, apart from pesticides, the evidence is inadequate and inconsistent as it differs not only in the population and time period analysed, but also in the type of study, the control of the confounding variables and the statistical methods used. In the latter case, the studies also differ in the adjustment of spatial and temporal variability. Our objective here, is to provide evidence on an association between environmental factors and ADHD. In our study, we used a population-based retrospective cohort in which we matched cases and controls (children free of the disease) by sex and year of birth (n = 5193, 78.9% boys). The cases were children born between 1998 and 2012 and diagnosed with ADHD (n = 116). To evaluate whether there was a geographical pattern in the incidence of ADHD, we first represented the smoothed standardized incidence rates on a map of the region being studied. We then estimated the probability of being a case by using a generalized liner mixed model with a binomial link. As explanatory variables of interest, we included the following environmental variables: distance to agricultural areas, distance to roads (stratified into three categories according to traffic density and intensity), distance to petrol stations, distance to industrial estates, and land use. We control for both observed (individual and family specific variables and deprivation index) and unobserved confounders (in particular, individual and familial heterogeneity). In addition, we adjusted for spatial extra variability. We found a north-south pattern containing two clusters (one in the centre of the study region and another in the south) in relation to the risk of developing ADHD. The results from the multivariate model suggest that these clusters could be related to some of the environmental variables. Specifically, living within 100 m from an agricultural area or a residential street and/or living fewer than 300 m from a motorway, dual carriageway or one of the industrial estates analysed was associated (statistically significant) with an increased risk of ADHD. Our results indicate that some environmental factors could be associated with ADHD occurring, particularly those associated with exposure to pesticides, organochlorine compounds and air pollutants because of traffic. Copyright © 2018 Elsevier Inc. All rights reserved.

Educational differences in cardiovascular mortality: The role of shared family factors and cardiovascular risk factors.

PubMed

Kjøllesdal, M K R; Ariansen, I; Mortensen, L H; Davey Smith, G; Næss, Ø

2016-12-01

To explore the confounding effects of early family factors shared by siblings and cardiovascular risk factors in midlife on the educational differences in mortality from cardiovascular disease (CVD). Data from national and regional health surveys in Norway (1974-2003) were linked with data from the Norwegian Family Based Life Course Study, the National Educational Registry and the Cause of Death Registry. The study population consisted of participants with at least one full sibling among the health survey participants ( n=271,310). Data were available on CVD risk factors, including weight, height, blood pressure, total cholesterol and smoking. The hazards ratio (HR) of CVD mortality was 3.44 (95% confidence interval (CI) 2.98-3.96) in the lowest educational group relative to the highest. The HRs were little altered in the within-sibship analyses. Adjusted for risk factors, the HR for CVD mortality in the cohort analyses was 2.05 (CI 1.77-2.37) in the lowest educational group relative to the highest. The respective HR in the within-sibship analyses was 2.46 (CI 1.48-2.24). Using a sibling design, we did not find that the association between education and CVD mortality was confounded by early life factors shared by siblings, but it was explained to a large extent by CVD risk factors. These results suggest that reducing levels of CVD risk factors could have the greatest effect on mortality in less well-educated people.

Exogenous factors matter when interpreting the results of an impact evaluation: a case study of rainfall and child health programme intervention in Rwanda.

PubMed

Mukabutera, Assumpta; Thomson, Dana R; Hedt-Gauthier, Bethany L; Atwood, Sidney; Basinga, Paulin; Nyirazinyoye, Laetitia; Savage, Kevin P; Habimana, Marcellin; Murray, Megan

2017-12-01

Public health interventions are often implemented at large scale, and their evaluation seems to be difficult because they are usually multiple and their pathways to effect are complex and subject to modification by contextual factors. We assessed whether controlling for rainfall-related variables altered estimates of the efficacy of a health programme in rural Rwanda and have a quantifiable effect on an intervention evaluation outcomes. We conducted a retrospective quasi-experimental study using previously collected cross-sectional data from the 2005 and 2010 Rwanda Demographic and Health Surveys (DHS), 2010 DHS oversampled data, monthly rainfall data collected from meteorological stations over the same period, and modelled output of long-term rainfall averages, soil moisture, and rain water run-off. Difference-in-difference models were used. Rainfall factors confounded the PIH intervention impact evaluation. When we adjusted our estimates of programme effect by controlling for a variety of rainfall variables, several effectiveness estimates changed by 10% or more. The analyses that did not adjust for rainfall-related variables underestimated the intervention effect on the prevalence of ARI by 14.3%, fever by 52.4% and stunting by 10.2%. Conversely, the unadjusted analysis overestimated the intervention's effect on diarrhoea by 56.5% and wasting by 80%. Rainfall-related patterns have a quantifiable effect on programme evaluation results and highlighted the importance and complexity of controlling for contextual factors in quasi-experimental design evaluations. © 2017 John Wiley & Sons Ltd.

Effects of Polyphenol, Measured by a Biomarker of Total Polyphenols in Urine, on Cardiovascular Risk Factors After a Long-Term Follow-Up in the PREDIMED Study

PubMed Central

Guo, Xiaohui; Tresserra-Rimbau, Anna; Estruch, Ramón; Martínez-González, Miguel A.; Medina-Remón, Alexander; Castañer, Olga; Corella, Dolores; Lamuela-Raventós, Rosa M.

2016-01-01

Several epidemiological studies have shown an inverse association between the consumption of polyphenol-rich foods and risk of cardiovascular diseases. However, accuracy and reliability of these studies may be increased using urinary total polyphenol excretion (TPE) as a biomarker for total polyphenol intake. Our aim was to assess if antioxidant activity, measured by a Folin-Ciocalteu assay in urine, is correlated with an improvement in cardiovascular risk factors (blood pressure and serum glucose, cholesterol, HDL-cholesterol, LDL-cholesterol, and triglyceride concentrations) in an elderly population at high risk. A longitudinal study was performed with 573 participants (aged 67.3 ± 5.9) from the PREDIMED study (ISRCTN35739639). We used Folin-Ciocalteu method to determine TPE in urine samples, assisting with solid phase extraction. Participants were categorized into three groups according to changes in TPE. Multiple linear regression models were used to assess relationships between TPE and clinical cardiovascular risk factors, adjusting for potential confounders. After a 5-year follow-up, significant inverse correlations were observed between changes in TPE and plasma triglyceride concentration (β = −8.563; P = 0.007), glucose concentration (β = −4.164; P = 0.036), and diastolic blood pressure (β = −1.316; P = 0.013). Our results suggest that the consumption of more polyphenols, measured as TPE in urine, could exert a protective effect against some cardiovascular risk factors. PMID:26881019

WHAT TO DO IF THERE IS NO REFERENCE SYSTEM

EPA Science Inventory

Efficient management and regulation of anthropogenic point source inputs requires a demonstrated and measurable ecological effect. In all ecosystems, the evaluation of anthropogenic effects is confounded by the effects of naturally existing environmental factors and river nonpoin...

Determinants of antithrombotic choice for patent foramen ovale in cryptogenic stroke.

PubMed

Thaler, David E; Ruthazer, Robin; Weimar, Christian; Serena, Joaquín; Mattle, Heinrich P; Nedeltchev, Krassen; Mono, Marie-Luise; Di Angelantonio, Emanuele; Elkind, Mitchell S V; Di Tullio, Marco R; Homma, Shunichi; Michel, Patrik; Meier, Bernhard; Furlan, Anthony J; Lutz, Jennifer S; Kent, David M

2014-11-18

We examined the influence of clinical, radiologic, and echocardiographic characteristics on antithrombotic choice in patients with cryptogenic stroke (CS) and patent foramen ovale (PFO), hypothesizing that features suggestive of paradoxical embolism might lead to greater use of anticoagulation. The Risk of Paradoxical Embolism Study combined 12 databases to create the largest dataset of patients with CS and known PFO status. We used generalized linear mixed models with a random effect of component study to explore whether anticoagulation was preferentially selected based on the following: (1) younger age and absence of vascular risk factors, (2) "high-risk" echocardiographic features, and (3) neuroradiologic findings. A total of 1,132 patients with CS and PFO treated with anticoagulation or antiplatelets were included. Overall, 438 participants (39%) were treated with anticoagulation with a range (by database) of 22% to 54%. Treatment choice was not influenced by age or vascular risk factors. However, neuroradiologic findings (superficial or multiple infarcts) and high-risk echocardiographic features (large shunts, shunt at rest, and septal hypermobility) were predictors of anticoagulation use. Both antithrombotic regimens are widely used for secondary stroke prevention in patients with CS and PFO. Radiologic and echocardiographic features were strongly associated with treatment choice, whereas conventional vascular risk factors were not. Prior observational studies are likely to be biased by confounding by indication. © 2014 American Academy of Neurology.

Structure and Correlates of Cognitive Aging in a Narrow Age Cohort

PubMed Central

2014-01-01

Aging-related changes occur for multiple domains of cognitive functioning. An accumulating body of research indicates that, rather than representing statistically independent phenomena, aging-related cognitive changes are moderately to strongly correlated across domains. However, previous studies have typically been conducted in age-heterogeneous samples over longitudinal time lags of 6 or more years, and have failed to consider whether results are robust to a comprehensive set of controls. Capitalizing on 3-year longitudinal data from the Lothian Birth Cohort of 1936, we took a longitudinal narrow age cohort approach to examine cross-domain cognitive change interrelations from ages 70 to 73 years. We fit multivariate latent difference score models to factors representing visuospatial ability, processing speed, memory, and crystallized ability. Changes were moderately interrelated, with a general factor of change accounting for 47% of the variance in changes across domains. Change interrelations persisted at close to full strength after controlling for a comprehensive set of demographic, physical, and medical factors including educational attainment, childhood intelligence, physical function, APOE genotype, smoking status, diagnosis of hypertension, diagnosis of cardiovascular disease, and diagnosis of diabetes. Thus, the positive manifold of aging-related cognitive changes is highly robust in that it can be detected in a narrow age cohort followed over a relatively brief longitudinal period, and persists even after controlling for many potential confounders. PMID:24955992

Suicide and occupation: further supportive evidence for their relevance.

PubMed

Nishimura, Mariko; Terao, Takeshi; Soeda, Shuji; Nakamura, Jun; Iwata, Noboru; Sakamoto, Kaoru

2004-01-01

In recent years, the relationship between occupation and suicide has been extensively investigated, but few definite conclusions regarding the nature of the relationship have been established. In the present study, this relationship was investigated by examining Japanese governmental statistics. First, correlations of suicide rate relative to industry categories were examined individually for primary industry (farmers, fishermen, and forest workers), secondary industry (construction workers, manufacture works, and miners), and tertiary industry (indoor workers) for all of the 47 prefectures of Japan. Second, in the industries that showed a significant correlation with suicide rate, the relationship to other factors was adjusted using possibly confounding factors. As a result, suicide rate was positively correlated with primary industry percentage, but not with secondary or tertiary industry percentages. Multiple regression analysis showed that suicide rate was positively associated with primary industry percentage with significant tendency while it was significantly and negatively associated with annual total sunshine. Limitations are that individual suicide rates according to occupational types were not available and direct correlations with the above variables could not be investigated. The present findings suggest a possibility that occupational factors associated with primary industry may be relevant to suicide, and that, additionally, annual total sunshine may affect suicide independently. Since workers with primary industry are likely to be exposed to sunshine than other workers, they may tend to be more affected by the decrease of annual total sunshine.

Structure and correlates of cognitive aging in a narrow age cohort.

PubMed

Tucker-Drob, Elliot M; Briley, Daniel A; Starr, John M; Deary, Ian J

2014-06-01

Aging-related changes occur for multiple domains of cognitive functioning. An accumulating body of research indicates that, rather than representing statistically independent phenomena, aging-related cognitive changes are moderately to strongly correlated across domains. However, previous studies have typically been conducted in age-heterogeneous samples over longitudinal time lags of 6 or more years, and have failed to consider whether results are robust to a comprehensive set of controls. Capitalizing on 3-year longitudinal data from the Lothian Birth Cohort of 1936, we took a longitudinal narrow age cohort approach to examine cross-domain cognitive change interrelations from ages 70 to 73 years. We fit multivariate latent difference score models to factors representing visuospatial ability, processing speed, memory, and crystallized ability. Changes were moderately interrelated, with a general factor of change accounting for 47% of the variance in changes across domains. Change interrelations persisted at close to full strength after controlling for a comprehensive set of demographic, physical, and medical factors including educational attainment, childhood intelligence, physical function, APOE genotype, smoking status, diagnosis of hypertension, diagnosis of cardiovascular disease, and diagnosis of diabetes. Thus, the positive manifold of aging-related cognitive changes is highly robust in that it can be detected in a narrow age cohort followed over a relatively brief longitudinal period, and persists even after controlling for many potential confounders. PsycINFO Database Record (c) 2014 APA, all rights reserved.

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.

Effectiveness and confounding factors of penetrating astigmatic keratotomy in clinical practice

PubMed Central

Yen, Chu-Yu; Tseng, Gow-Lieng

2018-01-01

Abstract Rationale: Penetrating astigmatic keratotomy (penetrating AK) is a well-known method to correct corneal astigmatism but rarely be performed nowadays. This article reevaluated the clinical effectiveness and confounding factors of penetrating AK. Patient concerns: Penetrating AK has been introduced to serve as one alternative operation for astigmatism correction, and is thought to have the potential advantage of being more affordable and easy to perform. The purpose of our study is to evaluate the effectiveness and confounding factors of penetrating AK. Diagnoses: The chart of 95 patients with corneal astigmatism (range: 0.75–3.25 diopters [D]) who received penetrating AK from January 2014 to December 2016 was collected. The corneal astigmatism were measured by an autokeratometer (Topcon KR8100PA topographer-autorefractor), and repeated with manual keratometer in low reproducibility cases. Interventions: All patients received penetrating AK by an experienced ophthalmologist (Dr. Gow-Lieng Tseng, MD, PHD) in the operation room. Among which, 66 patients received penetrating AK with phacoemulsification simultaneously (group A), whereas 29 patients received penetrating AK at least 3 months after phacoemulsification (group B). After excluding the patients combined with other procedures or lost followed up, 79 patients are remaining for analysis. The outcome was evaluated by net correction, the difference between preoperative corneal astigmatism (PCA) and residual corneal astigmatism (RCA). Two sample t tests and Pearson test were used for effectiveness evaluation. For confounding factors, multivariate linear regression was used for statistical analysis. Outcomes: The mean preoperative and postoperative refractive cylinders were 1.97 ± 0.77 and 1.08 ± 0.64 D, respectively, in group A and 2.62 ± 1.05 and 1.51 ± 0.89 D in group B. There were no statistically significant differences in net correction between these two groups (0.9 ± 0.66 vs. 1.1 ± 0.69, P = .214). Higher PCA were associated with higher net correction in both group A (P = .002) and group B (P = .019). Compound myopic astigmatism caused less net correction than others only in group A (P = 0.031). Lessons: Penetrating AK is an accessible, affordable, and effective way to correct corneal astigmatism. The results of this procedure are comparable to modern methods in patients with low to moderate corneal astigmatism. PMID:29369200

Metabolic syndrome and shift work: a systematic review.

PubMed

Canuto, Raquel; Garcez, Anderson S; Olinto, Maria T A

2013-12-01

The aim of this systematic review was to examine the association between shift work and metabolic syndrome (MetS) as well as the potential confounders investigated. A systematic search was conducted with the aim of finding original articles on the association between shift work and MetS. The included articles were chosen based on established inclusion criteria; their methodological quality was assessed using a validated quality checklist. A total of 10 articles were included in this review. The majority of the studies were classified as having a low risk of bias. The definitions of MetS and shift work varied between studies. Among the ten studies, eight found a positive association between shift work and MetS after controlling for socio-demographic and behavioral factors. Only three studies included sleep duration as a confounder, and these studies presented discordant results. We conclude that there was insufficient evidence regarding the association between shift work and prevalent MetS when the confounders are taken into account. Copyright © 2012 Elsevier Ltd. All rights reserved.

'Mechanical restraint-confounders, risk, alliance score': testing the clinical validity of a new risk assessment instrument.

PubMed

Deichmann Nielsen, Lea; Bech, Per; Hounsgaard, Lise; Alkier Gildberg, Frederik

2017-08-01

Unstructured risk assessment, as well as confounders (underlying reasons for the patient's risk behaviour and alliance), risk behaviour, and parameters of alliance, have been identified as factors that prolong the duration of mechanical restraint among forensic mental health inpatients. To clinically validate a new, structured short-term risk assessment instrument called the Mechanical Restraint-Confounders, Risk, Alliance Score (MR-CRAS), with the intended purpose of supporting the clinicians' observation and assessment of the patient's readiness to be released from mechanical restraint. The content and layout of MR-CRAS and its user manual were evaluated using face validation by forensic mental health clinicians, content validation by an expert panel, and pilot testing within two, closed forensic mental health inpatient units. The three sub-scales (Confounders, Risk, and a parameter of Alliance) showed excellent content validity. The clinical validations also showed that MR-CRAS was perceived and experienced as a comprehensible, relevant, comprehensive, and useable risk assessment instrument. MR-CRAS contains 18 clinically valid items, and the instrument can be used to support the clinical decision-making regarding the possibility of releasing the patient from mechanical restraint. The present three studies have clinically validated a short MR-CRAS scale that is currently being psychometrically tested in a larger study.

Is the Association of Subjective SES and Self-Rated Health Confounded by Negative Mood? An Experimental Approach

PubMed Central

Kraus, Michael W.; Adler, Nancy; David Chen, Teh-Way

2012-01-01

Objective Lower subjective socioeconomic status (SSS) consistently shows associations with poorer health with the strongest relationships emerging with global self-rated health. Though often interpreted as reflecting the impact of low SSS on health, the association could also arise from confounding SSS with negative affect. In this research we sought to determine if negative affect confounds, or alternatively, is on the causal pathway linking SSS to self-rated health. Methods 300 adult participants—recruited from throughout the United States—were randomized to experience sadness, shame, or a neutral mood induction wherein they wrote about and visualized a particularly emotionally evocative event. Participants subsequently completed measures of SSS, self-rated health, depression, and negative mood. Results Consistent with predictions, neither SSS scores nor the association of SSS with self-rated health, depression, and chronic negative affect differed by mood induction condition, controlling for demographic factors that covary with SSS (e.g., age, gender, education, income). Moreover, chronic negative affect partially explained the relationship between SSS and self-rated health, independent of manipulated mood. Conclusions These findings support the utility of the measurement of SSS, and provide evidence suggesting that chronic negative affect is a likely mediator of the SSS association with global health rather than a confounder. PMID:22329426

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.

Treatment with insulin analogs and prevalence of cardiovascular complications in patients with type 1 diabetes.

PubMed

Hasslacher, Christoph; Lorenzo Bermejo, Justo

2017-11-01

A lower incidence of cardiovascular events has been reported in type 2 diabetes patients treated with insulin analogs (IAs). Corresponding data on people affected by type 1 diabetes are not available yet. We investigated demographic and clinical data from 509 type 1 diabetics, who were treated in an outpatient clinic from 2006 to 2012. Multiple logistic regression was used to investigate the relationship between the type of insulin treatment and the prevalence of cardiovascular (CV) complications, that is, presence of coronary heart, cerebrovascular and peripheral arterial diseases, adjusting for potential confounders. Results from multiple logistic regression revealed that patients with impaired renal function [estimated glomerular filtration rate (eGFR) < 90 ml/min] show lower CV complication rates when treated with IAs (25%) compared with patients treated with human insulin (HI; 28%) and HI/IA (38%, p = 0.06). CV complication rates in the complete patient collective amounted to 17% (IA), 21% (HI) and 21% (HI/IA, p = 0.08). Examination of CV complications according to the type of IA revealed the lowest complication rates in type 1 diabetics treated with insulin lispro (5.9%) and glargine (16%). However, complication rate differences among insulin treatments did not reach statistical significance. The present cross-sectional study shows a borderline significantly lower CV morbidity in people with type 1 diabetes and impaired renal function when treated with IA compared with HI treatment after adjustment for multiple potential confounders [odds ratio (OR) = 0.78, which translates into a 22% lower complication rate]. Validation of these preliminary findings in confirmatory, prospective studies may have important clinical implications.

Absence of evidence for increase in risk for autism or attention-deficit hyperactivity disorder following antidepressant exposure during pregnancy: a replication study.

PubMed

Castro, V M; Kong, S W; Clements, C C; Brady, R; Kaimal, A J; Doyle, A E; Robinson, E B; Churchill, S E; Kohane, I S; Perlis, R H

2016-01-05

Multiple studies have examined the risk of prenatal antidepressant exposure and risk for autism spectrum disorder (ASD) or attention-deficit hyperactivity disorder (ADHD), with inconsistent results. Precisely estimating such risk, if any, is of great importance in light of the need to balance such risk with the benefit of depression and anxiety treatment. We developed a method to integrate data from multiple New England health systems, matching offspring and maternal health data in electronic health records to characterize diagnoses and medication exposure. Children with ASD or ADHD were matched 1:3 with children without neurodevelopmental disorders. Association between maternal antidepressant exposure and ASD or ADHD liability was examined using logistic regression, adjusting for potential sociodemographic and psychiatric confounding variables. In new cohorts of 1245 ASD cases and 1701 ADHD cases, along with age-, sex- and socioeconomic status matched controls, neither disorder was significantly associated with prenatal antidepressant exposure in crude or adjusted models (adjusted odds ratio 0.90, 95% confidence interval 0.50-1.54 for ASD; 0.97, 95% confidence interval 0.53-1.69 for ADHD). Pre-pregnancy antidepressant exposure significantly increased risk for both disorders. These results suggest that prior reports of association between prenatal antidepressant exposure and neurodevelopmental disease are likely to represent a false-positive finding, which may arise in part through confounding by indication. They further demonstrate the potential to integrate data across electronic health records studies spanning multiple health systems to enable efficient pharmacovigilance investigation.

THE LINK BETWEEN EARLY ONSET DRINKING AND EARLY ONSET ALCOHOL-IMPAIRED DRIVING IN YOUNG MALES

PubMed Central

Zhang, Lening; Wieczorek, William F.; Welte, John W.

2014-01-01

Background Young drivers represent a disproportionate number of the individuals involved in alcohol-impaired driving. Although there is a known association between drinking and alcohol-impaired driving in young drivers, the link between early onset drinking and early onset alcohol-impaired driving has not been explored. Objectives The present study aimed to assess this link along with potentially confounding factors. Methods The assessment used a proportional hazards model with data collected from the Buffalo Longitudinal Study of Young Men, a population based sample of 625 males at ages of 16–19 years old. Results Controlling for the effects of potentially relevant confounds, the early onset of drinking was the most influential factor in predicting the early onset of alcohol-impaired driving. Race and the early onset of other forms of delinquency also played a significant role in the early onset of alcohol-impaired driving. Conclusion Preventing an early start of drinking among adolescents may be the most critical factor to address in preventing an early start of alcohol-impaired driving. PMID:24766089

Older men with higher self-rated socioeconomic status have shorter telomeres

PubMed Central

Woo, Jean; Suen, Eddie W. C.; Leung, Jason C. S.; Tang, Nelson L. S.; Ebrahim, Shah

2009-01-01

Background: previous studies examining the relationship between socioeconomic status and telomere length showed conflicting results, one study finding shorter telomere length in subjects with lower socioeconomic status and one showing no relationship. Design: cross-sectional study. Setting: community-living elderly Chinese in Hong Kong. Objective: this study examines the relationship between self-rated social economic status and telomere length in Hong Kong Chinese men and women aged 65 years and over living in the community. Subjects and method: information was collected from 958 men and 978 women regarding possible confounding factors such as the presence of chronic diseases, smoking, physical activity level, dietary intake and body mass index. Telomere length was measured by quantitative PCR. Result: in men only, after adjustment for age and other confounding factors, a higher ranking in community standing was associated with shorter telomere length. Conclusion: men with higher self-rated socioeconomic status have shorter telomeres, possibly mediated through psychosocial rather than lifestyle factors or the presence of chronic disease. There may be cultural ethnic and age-related differences in social determinants of health. PMID:19556325

Linear mixed-effects modeling approach to FMRI group analysis

PubMed Central

Chen, Gang; Saad, Ziad S.; Britton, Jennifer C.; Pine, Daniel S.; Cox, Robert W.

2013-01-01

Conventional group analysis is usually performed with Student-type t-test, regression, or standard AN(C)OVA in which the variance–covariance matrix is presumed to have a simple structure. Some correction approaches are adopted when assumptions about the covariance structure is violated. However, as experiments are designed with different degrees of sophistication, these traditional methods can become cumbersome, or even be unable to handle the situation at hand. For example, most current FMRI software packages have difficulty analyzing the following scenarios at group level: (1) taking within-subject variability into account when there are effect estimates from multiple runs or sessions; (2) continuous explanatory variables (covariates) modeling in the presence of a within-subject (repeated measures) factor, multiple subject-grouping (between-subjects) factors, or the mixture of both; (3) subject-specific adjustments in covariate modeling; (4) group analysis with estimation of hemodynamic response (HDR) function by multiple basis functions; (5) various cases of missing data in longitudinal studies; and (6) group studies involving family members or twins. Here we present a linear mixed-effects modeling (LME) methodology that extends the conventional group analysis approach to analyze many complicated cases, including the six prototypes delineated above, whose analyses would be otherwise either difficult or unfeasible under traditional frameworks such as AN(C)OVA and general linear model (GLM). In addition, the strength of the LME framework lies in its flexibility to model and estimate the variance–covariance structures for both random effects and residuals. The intraclass correlation (ICC) values can be easily obtained with an LME model with crossed random effects, even at the presence of confounding fixed effects. The simulations of one prototypical scenario indicate that the LME modeling keeps a balance between the control for false positives and the sensitivity for activation detection. The importance of hypothesis formulation is also illustrated in the simulations. Comparisons with alternative group analysis approaches and the limitations of LME are discussed in details. PMID:23376789

Linear mixed-effects modeling approach to FMRI group analysis.

PubMed

Chen, Gang; Saad, Ziad S; Britton, Jennifer C; Pine, Daniel S; Cox, Robert W

2013-06-01

Conventional group analysis is usually performed with Student-type t-test, regression, or standard AN(C)OVA in which the variance-covariance matrix is presumed to have a simple structure. Some correction approaches are adopted when assumptions about the covariance structure is violated. However, as experiments are designed with different degrees of sophistication, these traditional methods can become cumbersome, or even be unable to handle the situation at hand. For example, most current FMRI software packages have difficulty analyzing the following scenarios at group level: (1) taking within-subject variability into account when there are effect estimates from multiple runs or sessions; (2) continuous explanatory variables (covariates) modeling in the presence of a within-subject (repeated measures) factor, multiple subject-grouping (between-subjects) factors, or the mixture of both; (3) subject-specific adjustments in covariate modeling; (4) group analysis with estimation of hemodynamic response (HDR) function by multiple basis functions; (5) various cases of missing data in longitudinal studies; and (6) group studies involving family members or twins. Here we present a linear mixed-effects modeling (LME) methodology that extends the conventional group analysis approach to analyze many complicated cases, including the six prototypes delineated above, whose analyses would be otherwise either difficult or unfeasible under traditional frameworks such as AN(C)OVA and general linear model (GLM). In addition, the strength of the LME framework lies in its flexibility to model and estimate the variance-covariance structures for both random effects and residuals. The intraclass correlation (ICC) values can be easily obtained with an LME model with crossed random effects, even at the presence of confounding fixed effects. The simulations of one prototypical scenario indicate that the LME modeling keeps a balance between the control for false positives and the sensitivity for activation detection. The importance of hypothesis formulation is also illustrated in the simulations. Comparisons with alternative group analysis approaches and the limitations of LME are discussed in details. Published by Elsevier Inc.

Birth weight and exposure to kitchen wood smoke during pregnancy in rural Guatemala.

PubMed

Boy, Erick; Bruce, Nigel; Delgado, Hernán

2002-01-01

In this study, we aimed to establish whether domestic use of wood fuel is associated with reduced birth weight, independent of key maternal, social, and economic confounding factors. We studied 1,717 women and newborn children in rural and urban communities in rural Guatemala. We identified subjects through home births reported by traditional birth attendants in six rural districts (n = 572) and all public hospital births in Quetzaltenango city during the study period (n = 1,145). All were seen within 72 hr of delivery, and data were collected on the type of household fuel used, fire type, and socioeconomic and other confounding factors. Smoking among women in the study community was negligible. Children born to mothers habitually cooking on open fires (n = 861) had the lowest mean birth weight of 2,819 g [95% confidence interval (CI), 2,790-2,848]; those using a chimney stove (n = 490) had an intermediate mean of 2,863 g (95% CI, 2,824-2,902); and those using the cleanest fuels (electricity or gas, n = 365) had the highest mean of 2,948 g (95% CI, 2,898-2,998) (p< 0.0001). The percentage of low birth weights (< 500 g) in these three groups was 19.9% (open fire), 16.8% (chimney stove), and 16.0% (electricity/gas), (trend (p = 0.08). Confounding factors were strongly associated with fuel type, but after adjustment wood users still had a birth weight 63 g lower (p = 0.05; 95% CI, 0.4-126). This is the first report of an association between biofuel use and reduced birth weight in a human population. Although there is potential for residual confounding despite adjustment, the better-documented evidence on passive smoking and a feasible mechanism through carbon monoxide exposure suggest this association may be real. Because two-thirds of households in developing countries still rely on biofuels and women of childbearing age perform most cooking tasks, the attributable risk arising from this association, if confirmed, could be substantial.

Birth weight and exposure to kitchen wood smoke during pregnancy in rural Guatemala.

PubMed Central

Boy, Erick; Bruce, Nigel; Delgado, Hernán

2002-01-01

In this study, we aimed to establish whether domestic use of wood fuel is associated with reduced birth weight, independent of key maternal, social, and economic confounding factors. We studied 1,717 women and newborn children in rural and urban communities in rural Guatemala. We identified subjects through home births reported by traditional birth attendants in six rural districts (n = 572) and all public hospital births in Quetzaltenango city during the study period (n = 1,145). All were seen within 72 hr of delivery, and data were collected on the type of household fuel used, fire type, and socioeconomic and other confounding factors. Smoking among women in the study community was negligible. Children born to mothers habitually cooking on open fires (n = 861) had the lowest mean birth weight of 2,819 g [95% confidence interval (CI), 2,790-2,848]; those using a chimney stove (n = 490) had an intermediate mean of 2,863 g (95% CI, 2,824-2,902); and those using the cleanest fuels (electricity or gas, n = 365) had the highest mean of 2,948 g (95% CI, 2,898-2,998) (p< 0.0001). The percentage of low birth weights (< 500 g) in these three groups was 19.9% (open fire), 16.8% (chimney stove), and 16.0% (electricity/gas), (trend (p = 0.08). Confounding factors were strongly associated with fuel type, but after adjustment wood users still had a birth weight 63 g lower (p = 0.05; 95% CI, 0.4-126). This is the first report of an association between biofuel use and reduced birth weight in a human population. Although there is potential for residual confounding despite adjustment, the better-documented evidence on passive smoking and a feasible mechanism through carbon monoxide exposure suggest this association may be real. Because two-thirds of households in developing countries still rely on biofuels and women of childbearing age perform most cooking tasks, the attributable risk arising from this association, if confirmed, could be substantial. PMID:11781172

Modifiable risk factors for chronic back pain: insights using the co-twin control design.

PubMed

Suri, Pradeep; Boyko, Edward J; Smith, Nicholas L; Jarvik, Jeffrey G; Williams, Frances M K; Jarvik, Gail P; Goldberg, Jack

2017-01-01

Inconsistent associations between modifiable risk factors and chronic back pain (CBP) may be due to the inability of traditional epidemiologic study designs to properly account for an array of potential genetic and environmental confounding factors. The co-twin control research design, comparing modifiable risk factors in twins discordant for CBP, offers a unique way to remove numerous confounding factors. The study aimed to examine the association of modifiable lifestyle and psychological factors with lifetime CBP. This is a cross-sectional co-twin control study in a nationwide sample of male twin members of the Vietnam Era Twin Registry. The sample is composed of 7,108 participants, including 1,308 monozygotic (MZ) pairs and 793 dizygotic pairs. The outcome measure is the self-reported lifetime history of CBP. Lifestyle factors included body mass index (BMI), smoking history, alcohol consumption, habitual physical activity, and typical sleep duration. Psychological factors included depression (Patient Health Questionnaire-9) and posttraumatic stress disorder (PTSD) symptoms (PTSD Checklist). Covariates included age, race, education, and income. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated for the association of risk factors with lifetime CBP when considering twins as individuals, and a within-pair co-twin control analysis that accounted for familial and genetic factors. Funding was through VA Grant 5IK2RX001515; there were no study-specific conflicts of interest. The mean age of respondents was 62 years and the prevalence of lifetime CBP was 28%. All lifestyle factors were associated with CBP in the individual level analysis. However, none of these persisted in the within-pair analyses, except for severe obesity (BMI ≥35.0), which was associated with lifetime CBP in both individual-level (OR=1.6, 95% CI: 1.3-1.9) and within-pair analyses (MZ analysis: OR=3.7, 95% CI: 1.2-11.4). Symptoms of PTSD and depression were strongly associated with lifetime CBP in both the individual-level (moderate or severe depression: OR=4.2, 95% CI: 3.6-4.9, and severe PTSD: OR=4.8, 95% CI: 4.0-5.7) and within-pair (MZ) analyses (moderate or severe depression: OR=4.6, 95% CI: 2.4-8.7, and severe PTSD: OR=3.2, 95% CI: 1.6-6.5). Many associations between modifiable lifestyle risk factors and CBP are due to confounding by familial and genetic factors. Severe obesity, depression, and PTSD should be considered in the development of intervention strategies to reduce the prevalence of CBP. Published by Elsevier Inc.

"A Bayesian sensitivity analysis to evaluate the impact of unmeasured confounding with external data: a real world comparative effectiveness study in osteoporosis".

PubMed

Zhang, Xiang; Faries, Douglas E; Boytsov, Natalie; Stamey, James D; Seaman, John W

2016-09-01

Observational studies are frequently used to assess the effectiveness of medical interventions in routine clinical practice. However, the use of observational data for comparative effectiveness is challenged by selection bias and the potential of unmeasured confounding. This is especially problematic for analyses using a health care administrative database, in which key clinical measures are often not available. This paper provides an approach to conducting a sensitivity analyses to investigate the impact of unmeasured confounding in observational studies. In a real world osteoporosis comparative effectiveness study, the bone mineral density (BMD) score, an important predictor of fracture risk and a factor in the selection of osteoporosis treatments, is unavailable in the data base and lack of baseline BMD could potentially lead to significant selection bias. We implemented Bayesian twin-regression models, which simultaneously model both the observed outcome and the unobserved unmeasured confounder, using information from external sources. A sensitivity analysis was also conducted to assess the robustness of our conclusions to changes in such external data. The use of Bayesian modeling in this study suggests that the lack of baseline BMD did have a strong impact on the analysis, reversing the direction of the estimated effect (odds ratio of fracture incidence at 24 months: 0.40 vs. 1.36, with/without adjusting for unmeasured baseline BMD). The Bayesian twin-regression models provide a flexible sensitivity analysis tool to quantitatively assess the impact of unmeasured confounding in observational studies. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Comparative analyses of studies of childhood leukemia and magnetic fields, radon and gamma radiation.

PubMed

Kheifets, Leeka; Swanson, John; Yuan, Yingzhe; Kusters, Cynthia; Vergara, Ximena

2017-06-26

In this paper we compare the findings of epidemiologic studies of childhood leukemia that examined at least two of ELF magnetic fields and/or distance to power lines, and exposure to radon and gamma radiation or distance to nuclear plants. Many of the methodologic aspects are common to studies of non-ionising (i.e. ELF-MF) and ionising radiation. A systematic search and review of studies with more than one exposure under study identified 33 key and 35 supplementary papers from ten countries that have been included in this review. Examining studies that have looked at several radiation exposures, and comparing similarities and differences for the different types of radiation, through the use of directed acyclic graphs, we evaluate to what extent bias, confounding and other methodological issues might be operating in these studies. We found some indication of bias, although results are not clear cut. There is little evidence that confounding has had a substantial influence on results. Influence of the residential mobility on the study conduct and interpretation is complex and can manifest as a selection bias, confounding, increased measurement error or could also be a potential risk factor. Other factors associated with distance to power lines and to nuclear power plants should be investigated. A more complete and consistent reporting of results in the future studies will allow for a more informative comparison across studies and integration of results.

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.

Maternal Smoking during Pregnancy and Children's Cognitive and Physical Development: A Causal Risk Factor?

PubMed Central

Gardener, Hannah; Buka, Stephen L.

2008-01-01

There remains considerable debate regarding the effects of maternal smoking during pregnancy on children's growth and development. Evidence that exposure to maternal smoking during pregnancy is associated with numerous adverse outcomes is contradicted by research suggesting that these associations are spurious. The authors investigated the relation between maternal smoking during pregnancy and 14 developmental outcomes of children from birth through age 7 years, using data from the Collaborative Perinatal Project (1959–1974; n = 52,919). In addition to adjusting for potential confounders measured contemporaneously with maternal smoking, the authors fitted conditional fixed-effects models among siblings that controlled for unmeasured confounders. Results from the conditional analyses indicated a birth weight difference of −85.63 g associated with smoking of ≥20 cigarettes daily during pregnancy (95% confidence interval: −131.91, −39.34) and 2.73 times' higher odds of being overweight at age 7 years (95% confidence interval: 1.30, 5.71). However, the associations between maternal smoking and 12 other outcomes studied (including Apgar score, intelligence, academic achievement, conduct problems, and asthma) were entirely eliminated after adjustment for measured and unmeasured confounders. The authors conclude that the hypothesized effects of maternal smoking during pregnancy on these outcomes either are not present or are not distinguishable from a broader range of familial factors associated with maternal smoking. PMID:18653646

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.

The art of matching brain tissue from patients and controls for postmortem research.

PubMed

Bao, Ai-Min; Swaab, Dick F

2018-01-01

The quality of postmortem research depends strongly on a thorough clinical investigation and documentation of the patient's disorder and therapies. In addition, a systematic and professional neuropathologic investigation of both cases and controls is absolutely crucial. In the experience of the Netherlands Brain Bank (NBB), about 20% of clinical neurologic diagnoses, despite being made in first-rate clinics, have to be revised or require an extra diagnosis after a complete and thorough review by the NBB. The neuropathology examination may reveal for instance that the "controls" already have preclinical neurodegenerative alterations. In postmortem studies the patient and control groups must be matched for as many of the known confounding factors as possible. This is necessary to make the groups as similar as possible, except for the topic being investigated. Confounding factors are present before, during, and after death. They are respectively: (1) genetic background, systemic diseases, duration and gravity of illness, medicines and addictive compounds used, age, sex, gender identity, sexual orientation, circadian and seasonal fluctuations, lateralization; (2) agonal state, stress of dying; and (3) postmortem delay, freezing procedures, fixation and storage time. Consequently, a brain bank should have a large number of controls at its disposal for appropriate matching. If matching fails for some confounders, then their influence may be determined by statistical methods such as analysis of variance or regression models. Copyright © 2018 Elsevier B.V. All rights reserved.

Infrared Spectroscopic Imaging for Prostate Pathology Practice

DTIC Science & Technology

2011-04-01

features – geometric properties of epithelial cells/nuclei and lumens – that are quantified based on H&E stained images as well as FT-IR images of...the samples. By restricting the features used to geometric measures, we sought to mimic the pattern recognition process employed by human experts, and...relatively dark and can be modeled as small elliptical areas in the stained images. This geometrical model is often confounded as multiple nuclei can be

Associations of Sleep Quality and Awake Physical Activity with Fluctuations in Nocturnal Blood Pressure in Patients with Cardiovascular Risk Factors

PubMed Central

Kadoya, Manabu; Koyama, Hidenori; Kurajoh, Masafumi; Naka, Mariko; Miyoshi, Akio; Kanzaki, Akinori; Kakutani, Miki; Shoji, Takuhito; Moriwaki, Yuji; Yamamoto, Tetsuya; Inaba, Masaaki; Namba, Mitsuyoshi

2016-01-01

Background Sleep quality and awake physical activity are important behavioral factors involved in the occurrence of cardiovascular diseases, potentially through nocturnal blood pressure (BP) changes. However, the impacts of quantitatively measured sleep quality and awake physical activity on BP fluctuation, and their relationships with several candidate causal factors for nocturnal hypertension are not well elucidated. Methods This cross-sectional study included 303 patients registered in the HSCAA study. Measurements included quantitatively determined sleep quality parameters and awake physical activity obtained by actigraph, nocturnal systolic BP (SBP) fall [100 × (1- sleep SBP/awake SBP ratio)], apnea hypopnea index, urinary sodium and cortisol secretion, plasma aldosterone concentration and renin activity, insulin resistance index, parameters of heart rate variability (HRV), and plasma brain-derived neurotrophic factor (BDNF). Results Simple regression analysis showed that time awake after sleep onset (r = -0.150), a parameter of sleep quality, and awake physical activity (r = 0.164) were significantly correlated with nocturnal SBP fall. Among those, time awake after sleep onset (β = -0.179) and awake physical activity (β = 0.190) were significantly and independently associated with nocturnal SBP fall in multiple regression analysis. In a subgroup of patients without taking anti-hypertensive medications, both time awake after sleep onset (β = -0.336) and awake physical activity (β = 0.489) were more strongly and independently associated with nocturnal SBP falls. Conclusion Sleep quality and awake physical activity were found to be significantly associated with nocturnal SBP fall, and that relationship was not necessarily confounded by candidate causal factors for nocturnal hypertension. PMID:27166822

An association between air pollution and daily outpatient visits for respiratory disease in a heavy industry area.

PubMed

Wang, Kuo-Ying; Chau, Tang-Tat

2013-01-01

In this work we used daily outpatient data from the Landseed Hospital in a heavily industrial area in northern Taiwan to study the associations between daily outpatient visits and air pollution in the context of a heavily polluted atmospheric environment in Chung-Li area during the period 2007-2011. We test the normality of each data set, control for the confounding factors, and calculate correlation coefficient between the outpatient visits and air pollution and meteorology, and use multiple linear regression analysis to seek significance of these associations. Our results show that temperature and relative humidity tend to be negatively associated with respiratory diseases. NO and [Formula: see text] are two main air pollutants that are positively associated with respiratory diseases, followed by [Formula: see text], [Formula: see text], [Formula: see text], CO, and [Formula: see text]. Young outpatients (age 0-15 years) are most sensitive to changing air pollution and meteorology factors, followed by the eldest (age [Formula: see text]66 years) and age 16-65 years of outpatients. Outpatients for COPD diseases are most sensitive to air pollution and meteorology factors, followed by allergic rhinitis, asthma, and pneumonia diseases. In the context of sex difference to air pollution and meteorological factors, male outpatients are more sensitive than female outpatients in the 16-65 age groups, while female outpatients are more sensitive than male outpatients in the young 0-15 age groups and in the eldest age groups. In total, female outpatients are more sensitive to air pollution and meteorological factors than male outpatients.

Confounding factors in the detection of species responses to habitat fragmentation.

PubMed

Ewers, Robert M; Didham, Raphael K

2006-02-01

Habitat loss has pervasive and disruptive impacts on biodiversity in habitat remnants. The magnitude of the ecological impacts of habitat loss can be exacerbated by the spatial arrangement -- or fragmentation -- of remaining habitat. Fragmentation per se is a landscape-level phenomenon in which species that survive in habitat remnants are confronted with a modified environment of reduced area, increased isolation and novel ecological boundaries. The implications of this for individual organisms are many and varied, because species with differing life history strategies are differentially affected by habitat fragmentation. Here, we review the extensive literature on species responses to habitat fragmentation, and detail the numerous ways in which confounding factors have either masked the detection, or prevented the manifestation, of predicted fragmentation effects. Large numbers of empirical studies continue to document changes in species richness with decreasing habitat area, with positive, negative and no relationships regularly reported. The debate surrounding such widely contrasting results is beginning to be resolved by findings that the expected positive species-area relationship can be masked by matrix-derived spatial subsidies of resources to fragment-dwelling species and by the invasion of matrix-dwelling species into habitat edges. Significant advances have been made recently in our understanding of how species interactions are altered at habitat edges as a result of these changes. Interestingly, changes in biotic and abiotic parameters at edges also make ecological processes more variable than in habitat interiors. Individuals are more likely to encounter habitat edges in fragments with convoluted shapes, leading to increased turnover and variability in population size than in fragments that are compact in shape. Habitat isolation in both space and time disrupts species distribution patterns, with consequent effects on metapopulation dynamics and the genetic structure of fragment-dwelling populations. Again, the matrix habitat is a strong determinant of fragmentation effects within remnants because of its role in regulating dispersal and dispersal-related mortality, the provision of spatial subsidies and the potential mediation of edge-related microclimatic gradients. We show that confounding factors can mask many fragmentation effects. For instance, there are multiple ways in which species traits like trophic level, dispersal ability and degree of habitat specialisation influence species-level responses. The temporal scale of investigation may have a strong influence on the results of a study, with short-term crowding effects eventually giving way to long-term extinction debts. Moreover, many fragmentation effects like changes in genetic, morphological or behavioural traits of species require time to appear. By contrast, synergistic interactions of fragmentation with climate change, human-altered disturbance regimes, species interactions and other drivers of population decline may magnify the impacts of fragmentation. To conclude, we emphasise that anthropogenic fragmentation is a recent phenomenon in evolutionary time and suggest that the final, long-term impacts of habitat fragmentation may not yet have shown themselves.

Changes in Landscape Greenness and Climatic Factors over ...

EPA Pesticide Factsheets

Monitoring and quantifying changes in vegetation cover over large areas using remote sensing can be achieved using the Normalized Difference Vegetation Index (NDVI), an indicator of greenness. However, distinguishing gradual shifts in NDVI (e.g. climate change) versus direct and rapid changes (e.g., fire, land development) is challenging as changes can be confounded by time-dependent patterns, and variation associated with climatic factors. In the present study we leveraged a method, that we previously developed for a pilot study, to address these confounding factors by evaluating NDVI change using autoregression techniques that compare results from univariate (NDVI vs. time) and multivariate analyses (NDVI vs. time and climatic factors) for ~7,660,636 1-km2 pixels comprising the 48 contiguous states of the USA, over a 25-year period (1989−2013). NDVI changed significantly for 48% of the nation over the 25-year in the univariate analyses where most significant trends (85%) indicated an increase in greenness over time. By including climatic factors in the multivariate analyses of NDVI over time, the detection of significant NDVI trends increased to 53% (an increase of 5%). Comparisons of univariate and multivariate analyses for each pixel showed that less than 4% of the pixels had a significant NDVI trend attributable to gradual climatic changes while the remainder of pixels with a significant NDVI trend indicated that changes were due to direct factors. Whi

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.

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.

Removal of restrictions following primary THA with posterolateral approach does not increase the risk of early dislocation.

PubMed

Gromov, Kirill; Troelsen, Anders; Otte, Kristian Stahl; Ørsnes, Thue; Ladelund, Steen; Husted, Henrik

2015-01-01

Patient education and mobilization restrictions are often used in an attempt to reduce the risk of dislocation following primary THA. To date, there have been no studies investigating the safety of removal of mobilization restrictions following THA performed using a posterolateral approach. In this retrospective non-inferiority study, we investigated the rate of early dislocation following primary THA in an unselected patient cohort before and after removal of postoperative mobilization restrictions. From the Danish National Health Registry, we identified patients with early dislocation in 2 consecutive and unselected cohorts of patients who received primary THA at our institution from 2004 through 2008 (n = 946) and from 2010 through 2014 (n = 1,329). Patients in the first cohort were mobilized with functional restrictions following primary THA whereas patients in the second cohort were allowed unrestricted mobilization. Risk of early dislocation (within 90 days) was compared in the 2 groups and odds ratio (OR)-adjusted for possible confounders-was calculated. Reasons for early dislocation in the 2 groups were identified. When we adjusted for potential confounders, we found no increased risk of early dislocation within 90 days in patients who were mobilized without restrictions. Risk of dislocation within 90 days was lower (3.4% vs 2.8%), risk of dislocation within 30 days was lower (2.1% vs 2.0%), and risk of multiple dislocations (1.8% vs 1.1%) was lower in patients who were mobilized without restrictions, but not statistically significantly so. Increasing age was an independent risk factor for dislocation. Removal of mobilization restrictions from the mobilization protocol following primary THA performed with a posterolateral approach did not lead to an increased risk of dislocation within 90 days.

Cardiovascular Disease Outcomes Related to Early Stage Renal Impairment Following Liver Transplantation.

PubMed

VanWagner, Lisa B; Montag, Samantha; Zhao, Lihui; Allen, Norrina B; Lloyd-Jones, Donald M; Das, Arighno; Skaro, Anton I; Hohmann, Samuel; Friedewald, John J; Levitsky, Josh

2018-03-20

In the general population, even mild renal disease is associated with increased cardiovascular (CV) complications. Whether this is true in liver transplant recipients (LTR) is unknown. This was a retrospective cohort study of 671 LTR (2002-2012) from a large urban tertiary care center and 37,322 LTR using Vizient hospitalization data linked to the United Network for Organ Sharing. The MDRD4 equation estimated GFR (eGFR). Outcomes were 1-year CV complications (death/hospitalization from myocardial infarction, heart failure, atrial fibrillation, cardiac arrest, pulmonary embolism or stroke) and mortality. Latent mixture modeling identified trajectories in eGFR in the first LT year in the 671 patients. Mean(SD) eGFR was 72.1(45.7) ml/min/1.73m. Six distinct eGFR trajectories were identified in the local cohort (n=671): qualitatively Normal-Slow Decrease (4% of cohort), Normal-Rapid Decrease (4%), Mild-Stable (18%), Mild-Slow Decrease (35%), Moderate-Stable (30%), and Severe-Stable (9%). In multivariable analyses adjusted for confounders and baseline eGFR, the greatest odds of 1-year CV complications were in the Normal-Rapid Decrease group (OR, 95% CI: 10.6, 3.0-36.9). Among the national cohort, each 5-unit lower eGFR at LT was associated with a 2% and 5% higher hazard of all-cause and CV-mortality, respectively (p<0.0001) independent of multiple confounders. Even mild renal disease at the time of LT is a risk factor for posttransplant all-cause and CV mortality. More rapid declines in eGFR soon after LT correlate with risk of adverse CV outcomes, highlighting the need to study whether early renal preservation interventions also reduce CV complications.

Association between differential gene expression and body mass index among endometrial cancers from The Cancer Genome Atlas Project.

PubMed

Roque, Dario R; Makowski, Liza; Chen, Ting-Huei; Rashid, Naim; Hayes, D Neil; Bae-Jump, Victoria

2016-08-01

The Cancer Genome Atlas (TCGA) identified four integrated clusters for endometrial cancer (EC): POLE, MSI, CNL and CNH. We evaluated differences in gene expression profiles of obese and non-obese women with EC and examined the association of body mass index (BMI) within the clusters identified in TCGA. TCGA RNAseq data was used to identify genes related to increasing BMI among ECs. The POLE, MSI and CNL clusters were composed mostly of endometrioid EC. Patient BMI was compared between these three clusters with one-way ANOVA. Association between gene expression and BMI was also assessed while adjusting for confounding effects of potential confounding factors. p-Values testing the association between gene expression and BMI were adjusted for multiple hypothesis testing over the 20,531 genes considered. Mean BMI was statistically different between the ECs in the CNL (35.8) versus POLE (29.8) cluster (p=0.006) and approached significance for the MSI (33.0) versus CNL (35.8) cluster (p=0.05). 181 genes were significantly up- or down-regulated with increasing BMI in endometrioid EC (q-value<0.01), including LPL, IRS-1, IGFBP4, IGFBP7 and the progesterone receptor. DAVID functional annotation analysis revealed significant enrichment in "cell cycle" (adjusted p-value=1.5E-5) and "DNA metabolic processes" (adjusted p-value=1E-3) for the identified genes. Obesity related genes were found to be upregulated with increasing BMI among endometrioid ECs. Patients with POLE tumors have the lowest median BMI when compared to MSI and CNL. Given the heterogeneity among endometrioid EC, consideration should be given to abandoning the Type I and II classification of EC tumors. Copyright © 2016 Elsevier Inc. All rights reserved.

Dietary protein intake is associated with lean mass change in older, community-dwelling adults: the Health, Aging, and Body Composition (Health ABC) Study.

PubMed

Houston, Denise K; Nicklas, Barbara J; Ding, Jingzhong; Harris, Tamara B; Tylavsky, Frances A; Newman, Anne B; Lee, Jung Sun; Sahyoun, Nadine R; Visser, Marjolein; Kritchevsky, Stephen B

2008-01-01

Dietary surveys suggest that many older, community-dwelling adults consume insufficient dietary protein, which may contribute to the age-related loss of lean mass (LM). The objective of the study was to determine the association between dietary protein and changes in total LM and nonbone appendicular LM (aLM) in older, community-dwelling men and women. Dietary protein intake was assessed by using an interviewer-administered 108-item food-frequency questionnaire in men and women aged 70-79 y who were participating in the Health, Aging, and Body Composition study (n=2066). Changes in LM and aLM over 3 y were measured by using dual-energy X-ray absorptiometry. The association between protein intake and 3-y changes in LM and aLM was examined by using multiple linear regression analysis adjusted for potential confounders. After adjustment for potential confounders, energy-adjusted protein intake was associated with 3-y changes in LM [beta (SE): 8.76 (3.00), P=0.004] and aLM [beta (SE): 5.31 (1.64), P=0.001]. Participants in the highest quintile of protein intake lost approximately 40% less LM and aLM than did those in the lowest quintile of protein intake (x+/-SE: -0.501+/-0.106 kg compared with -0.883+/-0.104 kg for LM; -0.400+/-0.058 kg compared with -0.661+/-0.057 kg for aLM; P for trend<0.01). The associations were attenuated slightly after adjustment for change in fat mass, but the results remained significant. Dietary protein may be a modifiable risk factor for sarcopenia in older adults and should be studied further to determine its effects on preserving LM in this population.

Relationship Between Circulating Concentrations of Thyrotropin, Free Thyroxine, and Free Triiodothyronine and 9-Year Mortality in Euthyroid Elderly Subjects

PubMed Central

Ceresini, Graziano; Marina, Michela; Lauretani, Fulvio; Maggio, Marcello; Bandinelli, Stefania; Ceda, Gian Paolo; Ferrucci, Luigi

2015-01-01

Objectives Thyroid dysfunction in the elderly is associated with adverse clinical outcomes, with mortality being associated with low TSH. However, it is still unknown whether variability of thyroid function test within the reference range is associated with mortality in older adults. We studied the association between plasma levels of TSH, free T3 (FT3), and free T4 (FT4), and all-cause mortality in older adults who had all three hormones within the normal range. Design Longitudinal study Setting Community-based Participants Total of 815 euthyroid participants of the InCHIANTI study, aged 65 years or older Measurements All subjects had TSH, FT3, and FT4 within the reference range at baseline. Plasma TSH, FT3 and FT4 were predictors and 9-year all-cause mortality was the outcome. Cox proportional hazards models adjusted for confounders were used to examine the relationship between quartiles of TSH, FT3, and FT4 and all-cause mortality over 9 years of follow-up. Results During the follow-up (mean persons-years 8643.74 [min-max, 35.36-16985.00]), 181 deaths occurred (22.2%). Participants with TSH in the lower quartile had higher mortality than the rest of the population. After adjusting for multiple confounders, participants with TSH in the lowest quartile (Hazard Ratio: 2.22; 95% Confidence Interval: 1.19–4.22) had significantly higher all-cause mortality than those with TSH in the highest quartile. Neither FT3 nor FT4 were associated with mortality. Conclusions In euthyroid elderly subjects, normal-low TSH represents an independent risk factor for all-cause mortality. PMID:27000328

Risk of Retinal Vein Occlusion in Patients With End-Stage Renal Disease: A 12-Year, Retrospective, Nationwide Cohort Study in South Korea.

PubMed

Lee, Kyung Sik; Nam, Ki Heon; Kim, Dong Wook; Kang, Eui Chun; Koh, Hyoung Jun

2018-01-01

The present study aimed to evaluate the risk of retinal vein occlusion (RVO) in Korean patients with end-stage renal disease (ESRD). In this retrospective, nationwide, propensity score-matched cohort study, subjects were randomly enrolled from the 12-year longitudinal Korean National Health Insurance Service-National Sample Cohort 2002-2013 database comprising 1 million subjects. The ESRD group comprised 988 patients newly diagnosed with ESRD from 2003 onward by washing out data from 2002. The comparison group comprised 4940 (5 for each patient with ESRD) randomly selected propensity score-matched individuals not diagnosed with ESRD. Each sampled patient was tracked until 2013 for RVO development. Multiple conditional Cox regression analysis was performed to compare the risk of RVO between the two groups. The mean follow-up period was 7.37 years. The incidence of RVO was 3.95% in the ESRD group and 2.17% in the comparison group (P = 0.001). ESRD was associated with greater risk of RVO development after adjustment for possible confounders (adjusted hazard ratio [HR], 2.122; 95% confidence interval [CI], 1.396-3.226; P = 0.0004). The 50- to 60-year (adjusted HR, 2.635; 95% CI, 1.100-6.313; P = 0.0297) and 60- to 70-year (adjusted HR, 2.544; 95% CI, 1.059-6.110; P = 0.0368) age groups exhibited higher risk of RVO compared with the <40-year age group. Hyperlipidemia (adjusted HR, 1.670; 95% CI, 1.176-2.371; P = 0.0042) and hypertension (adjusted HR, 1.896; 95% CI, 1.165-3.086; P = 0.01) were also associated with RVO. An association between ESRD and subsequent RVO development was found after adjustment for possible confounding factors.