Moving into a new era of periodontal genetic studies: relevance of large case-control samples using severe phenotypes for genome-wide association studies.

PubMed

Vaithilingam, R D; Safii, S H; Baharuddin, N A; Ng, C C; Cheong, S C; Bartold, P M; Schaefer, A S; Loos, B G

2014-12-01

Studies to elucidate the role of genetics as a risk factor for periodontal disease have gone through various phases. In the majority of cases, the initial 'hypothesis-dependent' candidate-gene polymorphism studies did not report valid genetic risk loci. Following a large-scale replication study, these initially positive results are believed to be caused by type 1 errors. However, susceptibility genes, such as CDKN2BAS (Cyclin Dependend KiNase 2B AntiSense RNA; alias ANRIL [ANtisense Rna In the Ink locus]), glycosyltransferase 6 domain containing 1 (GLT6D1) and cyclooxygenase 2 (COX2), have been reported as conclusive risk loci of periodontitis. The search for genetic risk factors accelerated with the advent of 'hypothesis-free' genome-wide association studies (GWAS). However, despite many different GWAS being performed for almost all human diseases, only three GWAS on periodontitis have been published - one reported genome-wide association of GLT6D1 with aggressive periodontitis (a severe phenotype of periodontitis), whereas the remaining two, which were performed on patients with chronic periodontitis, were not able to find significant associations. This review discusses the problems faced and the lessons learned from the search for genetic risk variants of periodontitis. Current and future strategies for identifying genetic variance in periodontitis, and the importance of planning a well-designed genetic study with large and sufficiently powered case-control samples of severe phenotypes, are also discussed. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Nasopharyngeal Case-Control Study

Cancer.gov

A case-control study conducted in Taiwan between 1991-1994 among approximately 1,000 individuals to examine the role of viral, environmental, and genetic factors associated with the development of nasopharyngeal carcinoma

A general regression framework for a secondary outcome in case-control studies.

PubMed

Tchetgen Tchetgen, Eric J

2014-01-01

Modern case-control studies typically involve the collection of data on a large number of outcomes, often at considerable logistical and monetary expense. These data are of potentially great value to subsequent researchers, who, although not necessarily concerned with the disease that defined the case series in the original study, may want to use the available information for a regression analysis involving a secondary outcome. Because cases and controls are selected with unequal probability, regression analysis involving a secondary outcome generally must acknowledge the sampling design. In this paper, the author presents a new framework for the analysis of secondary outcomes in case-control studies. The approach is based on a careful re-parameterization of the conditional model for the secondary outcome given the case-control outcome and regression covariates, in terms of (a) the population regression of interest of the secondary outcome given covariates and (b) the population regression of the case-control outcome on covariates. The error distribution for the secondary outcome given covariates and case-control status is otherwise unrestricted. For a continuous outcome, the approach sometimes reduces to extending model (a) by including a residual of (b) as a covariate. However, the framework is general in the sense that models (a) and (b) can take any functional form, and the methodology allows for an identity, log or logit link function for model (a).

A nested case-control study of predictors for tuberculosis recurrence in a large UK Centre.

PubMed

Rosser, Andrew; Richardson, Matthew; Wiselka, Martin J; Free, Robert C; Woltmann, Gerrit; Mukamolova, Galina V; Pareek, Manish

2018-02-27

Tuberculosis (TB) recurrence represents a challenge to control programs. In low incidence countries, the prevailing risk factors leading to recurrence are poorly characterised. We conducted a nested case-control study using the Leicester TB service TBIT database. Cases were identified from database notifications between 1994 and 2014. Controls had one episode and were matched to cases on a ratio of two to one by the date of notification. Multiple imputation was used to account for missing data. Multivariate conditional logistic regression analysis was employed to identify clinical, sociodemographic and TB specific risk factors for recurrence. From a cohort of 4628 patients, 82 TB recurrences occurred (1.8%). Nineteen of 82 patients had paired isolates with MIRU-VNTR strain type profiles available, of which 84% were relapses and 16% reinfections. On multivariate analysis, smoking (OR 3.8; p = 0.04), grade 3/4 adverse drug reactions (OR 5.6; p = 0.02), ethnicity 'Indian subcontinent' (OR 8.5; p = <0.01), ethnicity 'other' (OR 31.2; p = 0.01) and receipt of immunosuppressants (OR 6.8; p = <0.01) were independent predictors of TB recurrence. Within this UK setting, the rate of TB recurrence was low, predominantly due to relapse. The identification of an elevated recurrence risk amongst the ethnic group contributing most cases to the national TB burden presents an opportunity to improve individual and population health.

Designing Case-Control Studies: Decisions About the Controls

PubMed Central

Hodge, Susan E.; Subaran, Ryan L.; Weissman, Myrna M.; Fyer, Abby J.

2014-01-01

The authors quantified, first, the effect of misclassified controls (i.e., individuals who are affected with the disease under study but who are classified as controls) on the ability of a case-control study to detect an association between a disease and a genetic marker, and second, the effect of leaving misclassified controls in the study, as opposed to removing them (thus decreasing sample size). The authors developed an informativeness measure of a study’s ability to identify real differences between cases and controls. They then examined this measure’s behavior when there are no misclassified controls, when there are misclassified controls, and when there were misclassified controls but they have been removed from the study. The results show that if, for example, 10% of controls are misclassified, the study’s informativeness is reduced to approximately 81% of what it would have been in a sample with no misclassified controls, whereas if these misclassified controls are removed from the study, the informativeness is only reduced to about 90%, despite the reduced sample size. If 25% are misclassified, those figures become approximately 56% and 75%, respectively. Thus, leaving the misclassified controls in the control sample is worse than removing them altogether. Finally, the authors illustrate how insufficient power is not necessarily circumvented by having an unlimited number of controls. The formulas provided by the authors enable investigators to make rational decisions about removing misclassified controls or leaving them in. PMID:22854929

Baldness and testicular cancer: the EPSAM case-control study.

PubMed

Moirano, G; Zugna, D; Grasso, C; Lista, P; Ciuffreda, L; Segnan, N; Merletti, F; Richiardi, L

2016-03-01

The etiology of testicular cancer is largely unexplained. Research has mainly focused on prenatal exposures, especially to sex hormones, while less attention has been paid to exposures that may act also postnatally. As baldness has been previously associated with testicular cancer risk we focused on baldness and body hairiness, which are both associated with androgen activity. We used data of the Postnatal Exposures and Male Health (EPSAM) study, a case-control study on testicular cancer conducted in the Province of Turin, Italy, involving cases diagnosed between 1997 and 2008. Information was collected using mailed questionnaires. Analyses included 255 cases and 459 controls. We calculated ORs and 95% CIs to estimate testicular cancer risk among those who developed baldness and among those with body hairiness. We found an inverse association between testicular cancer and baldness (OR: 0.67, 95% CI: 0.46-0.98) and body hairiness (OR: 0.78, 95% CI: 0.53-1.16), although the latter had wider CIs. The inverse association between baldness and testicular cancer is consistent with the results from previous studies. These results suggest that androgens activity may influence testicular cancer risk. © 2016 American Society of Andrology and European Academy of Andrology.

Pernicious anemia and colorectal cancer risk - A nested case-control study.

PubMed

Boursi, Ben; Mamtani, Ronac; Haynes, Kevin; Yang, Yu-Xiao

2016-11-01

Hypergastrinemia was shown to stimulate colonic epithelial cell proliferation. To evaluate the association between pernicious anemia (PA), a disease with hypergastrinemia, and colorectal cancer (CRC) risk. We conducted a nested case-control study within a large database from the UK. Cases were defined as all individuals in the cohort with at least one medical code for CRC. Controls were selected based on incidence-density sampling. For each case, up to four eligible controls were matched on age at diagnosis, sex, practice-site, and both duration and calendar time of follow-up. Exposure of interest was diagnosis of PA prior to CRC diagnosis date. The primary analysis was a multivariable conditional logistic regression. Our study included 22,098 CRC cases and 85,969 matched controls. We identified 154 (0.70%) cases and 563 (0.65%) controls with past history of PA. The adjusted OR for the association between PA and CRC risk was 1.02 (95% CI 0.85-1.22). There was no difference in the results after stratification according to sex. In a sensitivity analysis only among individuals without chronic use of proton pump inhibitors (PPIs) the adjusted OR was 1.14 (95% CI 0.90-1.45). There was no association between duration of PA and CRC risk. PA is not associated with higher CRC risk. Copyright © 2016. Published by Elsevier Ltd.

Observational Studies: Cohort and Case-Control Studies

PubMed Central

Song, Jae W.; Chung, Kevin C.

2010-01-01

Observational studies are an important category of study designs. To address some investigative questions in plastic surgery, randomized controlled trials are not always indicated or ethical to conduct. Instead, observational studies may be the next best method to address these types of questions. Well-designed observational studies have been shown to provide results similar to randomized controlled trials, challenging the belief that observational studies are second-rate. Cohort studies and case-control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. In this review article, we describe these study designs, methodological issues, and provide examples from the plastic surgery literature. PMID:20697313

Birth outcomes of cases with conotruncal defects of heart - a population-based case-control study.

PubMed

Vereczkey, Attila; Kósa, Zsolt; Csáky-Szunyogh, Melinda; Gerencsér, Balázs; Czeizel, Andrew E

2015-03-01

The aim of this study was to evaluate the birth outcomes of cases with four types of conotruncal defects (CTDs), i.e. common truncus, transposition of great arteries, tetralogy of Fallot and double-outlet right ventricle. Birth outcomes of 597 live-born cases with CTD and 38,151 population controls without any defects were compared in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities completed by socio-demographic variables of their mothers. There was a male excess in cases with CTD (56.8%) with the same mean gestational age (39.4 versus 39.4 weeks) and preterm birth rate (8.2 versus 9.2%), but their mean birth weight was smaller (3077 versus 3276 g) with a high rate of low birthweight (14.6 versus 5.7%) compared to the birth outcomes of population controls. These data indicate intrauterine growth restriction of fetuses affected with transposition of great arteries, tetralogy of Fallot and double-outlet right ventricle particularly in females, while there were a shorter mean gestational age and smaller mean birth weigh in cases with common truncus. In general CTD, except common truncus, had no effect for gestational age but associated with a high risk for intrauterine fetal growth restriction particularly in female cases.

Inflammatory potential of diet and risk of oral and pharyngeal cancer in a large case-control study from Italy.

PubMed

Shivappa, Nitin; Hébert, James R; Rosato, Valentina; Garavello, Werner; Serraino, Diego; La Vecchia, Carlo

2017-08-01

Diet and inflammation have been suggested to be important risk factors for oral and pharyngeal cancer. We examined the association between dietary inflammatory index (DII™) and oral and pharyngeal cancer in a large case-control study conducted between 1992 and 2009 in Italy. This study included 946 cases with incident, histologically confirmed oral and pharyngeal cancer, and 2,492 controls hospitalized for acute non-neoplastic diseases. The DII was computed based on dietary intake assessed by a valid 78-item food frequency questionnaire and was adjusted for nonalcohol energy intake using the residual approach (E-DII™). Logistic regression models were used to estimate odds ratios (ORs), and 95% confidence intervals (CIs), adjusted for age, sex, non-alcohol energy intake, study center, year of interview, education, body mass index, tobacco smoking, and alcohol drinking. Subjects with higher DII scores (i.e., with a more pro-inflammatory diet) had a higher risk of oral and pharyngeal cancer, the OR being 1.80 (95% CI 1.36-2.38) for the highest versus the lowest DII quartile and 1.17 (95% CI 1.10-1.25) for a one-unit increase (8% of the DII range). When stratified by selected covariates, a stronger association was observed among women (OR quartile4 v.1 3.30, 95% CI 1.95-5.57). We also observed a stronger association for oral cancers and a strong combined effect of higher DII score and tobacco smoking or alcohol consumption on oral and pharyngeal cancer. These results indicate that the pro-inflammatory potential of the diet, as shown by higher DII scores, is associated with higher odds of oral and pharyngeal cancer. © 2017 UICC.

Evaluating the use of friend or family controls in epidemiologic case-control studies.

PubMed

Zhong, Charlie; Cockburn, Myles; Cozen, Wendy; Voutsinas, Jenna; Lacey, James V; Luo, Jianning; Sullivan-Halley, Jane; Bernstein, Leslie; Wang, Sophia S

2017-02-01

Traditional methodologies for identifying and recruiting controls in epidemiologic case-control studies, such as random digit dialing or neighborhood walk, suffer from declining response rates. Here, we revisit the feasibility and comparability of using alternative sources of controls, specifically friend and family controls. We recruited from a recently completed case-control study of non-Hodgkin lymphoma (NHL) among women in Los Angeles County where controls from the parent study were ascertained by neighborhood walk. We calculated participation rates and compared questionnaire responses between the friend/family controls and the original matched controls from the parent study. Of the 182 NHL case patients contacted, 111 (61%) agreed to participate in our feasibility study. 70 (63%) provided contact information for potential friend and/or family member controls. We were able to successfully contact and recruit a friend/family member for 92% of the case patients. This represented 46 friend controls and 54 family controls. Family controls significantly differed from original matched controls by sex and household income. Other characteristics were similar between friend controls and the original study's neighborhood controls. The apparent comparability of neighborhood controls to friend and family controls among respondents in this study suggests that these alternative methods of control identification can serve as a complementary source of eligible controls in epidemiologic case-control studies. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

A case-control study of Nocardia mastitis in Nova Scotia dairy herds

PubMed Central

Ferns, Lyn; Dohoo, Ian; Donald, Alan

1991-01-01

A case-control study was conducted to identify herd production, housing, and hygienic and therapeutic factors associated with a diagnosis of Nocardia mastitis in dairy herds in Nova Scotia. The data were collected by on-farm interviews with owners of 54 case and 54 control herds. Logistic regression was used to study risk factors. The use of dry cow products containing neomycin, including two specific dry cow products, was strongly associated with a diagnosis of Nocardia mastitis in a herd. Other factors which increased the risk of Nocardia mastitis were higher levels of production, larger herd size, and a large percentage of cows treated with dry cow products. These results are compared to results from a similar study carried out in Ontario. PMID:17423896

Comparative study of control selection in a national population-based case-control study: Estimating risk of smoking on cancer deaths in Chinese men.

PubMed

Jiang, Jingmei; Liu, Boqi; Nasca, Philip C; Han, Wei; Zou, Xiaonong; Zeng, Xianjia; Tian, Xiaobing; Wu, Yanping; Zhao, Ping; Li, Junyao

2009-10-28

To assess the validation of a novel control selection design by comparing the consistency between the new design and a routine design in a large case-control study that was incorporated into a nationwide mortality survey in China. A nationwide mortality study was conducted during 1989-1991. Surviving spouses or other relatives of all adults who died during 1986-1988 provided detailed information about their own as well as the deceased person's smoking history. In this study, 130,079 males who died of various smoking-related cancers at age 35 or over were taken as cases, while 103,248 male surviving spouses (same age range with cases) of women who died during the same period and 49,331 males who died from causes other than those related to smoking were used as control group 1 and control group 2, respectively. Consistency in the results when comparing cases with each of the control groups was assessed. Consistency in the results was observed in the analyses using different control groups although cancer deaths varied with region and age. Equivalence could be ascertained using a 15% criterion in most cancer deaths which had high death rates in urban areas, but they were uncertain for most cancers in rural areas irrespective of whether the hypothesis testing showed significant differences or not. Sex-matched living spouse control design as an alternative control selection for a case-control study is valid and feasible, and the basic principles of the equivalence study are also supported by epidemiological survey data.

Case Studies in Modelling, Control in Food Processes.

PubMed

Glassey, J; Barone, A; Montague, G A; Sabou, V

This chapter discusses the importance of modelling and control in increasing food process efficiency and ensuring product quality. Various approaches to both modelling and control in food processing are set in the context of the specific challenges in this industrial sector and latest developments in each area are discussed. Three industrial case studies are used to demonstrate the benefits of advanced measurement, modelling and control in food processes. The first case study illustrates the use of knowledge elicitation from expert operators in the process for the manufacture of potato chips (French fries) and the consequent improvements in process control to increase the consistency of the resulting product. The second case study highlights the economic benefits of tighter control of an important process parameter, moisture content, in potato crisp (chips) manufacture. The final case study describes the use of NIR spectroscopy in ensuring effective mixing of dry multicomponent mixtures and pastes. Practical implementation tips and infrastructure requirements are also discussed.

Data Management and Data Quality in PERCH, a Large International Case-Control Study of Severe Childhood Pneumonia.

PubMed

Watson, Nora L; Prosperi, Christine; Driscoll, Amanda J; Higdon, Melissa M; Park, Daniel E; Sanza, Megan; DeLuca, Andrea N; Awori, Juliet O; Goswami, Doli; Hammond, Emily; Hossain, Lokman; Johnson, Catherine; Kamau, Alice; Kuwanda, Locadiah; Moore, David P; Neyzari, Omid; Onwuchekwa, Uma; Parker, David; Sapchookul, Patranuch; Seidenberg, Phil; Shamsul, Arifin; Siazeele, Kazungu; Srisaengchai, Prasong; Sylla, Mamadou; Levine, Orin S; Murdoch, David R; O'Brien, Katherine L; Wolff, Mark; Deloria Knoll, Maria

2017-06-15

The Pneumonia Etiology Research for Child Health (PERCH) study is the largest multicountry etiology study of pediatric pneumonia undertaken in the past 3 decades. The study enrolled 4232 hospitalized cases and 5325 controls over 2 years across 9 research sites in 7 countries in Africa and Asia. The volume and complexity of data collection in PERCH presented considerable logistical and technical challenges. The project chose an internet-based data entry system to allow real-time access to the data, enabling the project to monitor and clean incoming data and perform preliminary analyses throughout the study. To ensure high-quality data, the project developed comprehensive quality indicator, data query, and monitoring reports. Among the approximately 9000 cases and controls, analyzable laboratory results were available for ≥96% of core specimens collected. Selected approaches to data management in PERCH may be extended to the planning and organization of international studies of similar scope and complexity. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Risk factors for exudative age-related macular degeneration in a large French case-control study.

PubMed

Zerbib, Jennyfer; Delcourt, Cécile; Puche, Nathalie; Querques, Giuseppe; Cohen, Salomon Yves; Sahel, José; Korobelnik, Jean-François; Le Goff, Mélanie; Souied, Eric H

2014-06-01

The purpose of the CAP (Creteil AMD PHRC-funded) Study was to analyze risk factors of exudative age-related macular degeneration (AMD) in a large French case-control population. One thousand and twenty-four patients with exudative AMD and 275 controls were recruited. Information about lifestyle, medical history, and dietary intake were collected. Associations of risk factors were estimated using logistic regression. After multivariate adjustment, CFH Y402H and ARMS2 A69S polymorphisms were associated with very high risk for exudative AMD (OR = 6.21 and OR = 11.7, respectively, p < 0.0001). Risk for exudative AMD was increased in current smokers (OR = 3.79, p = 0.0003) and former smokers having quitted since less than 20 years ago (OR = 2.30, p = 0.002), but not in former smokers having quitted since 20 years or more ago (OR = 0.81, p = 0.43). Heavy smokers (at least 25 pack-years) were particularly at risk (OR = 3.61, p < 0.0001). Use of cooking oils rich in omega 3 fatty acids was significantly associated with a reduced risk of exudative AMD (OR = 0.55, 95 % CI: 0.36-0.84, p = 0.006), as well as a high consumption of fruits (OR = 0.60, 95 % CI: 0.37-0.98, p = 0.04), but not the consumption of fish, vegetables or oils rich in omega 6. High waist circumference was associated with increased risk for exudative AMD (OR = 2.53, p < 0.0001), but not hypercholesterolemia, hypertension, or body mass index. The CAP Study confirms major genetic risk factors for exudative AMD. It further documents the high risk in heavy smokers and the long persistence of risk after smoking cessation, and the associations with waist circumference and fruit consumption. Furthermore, we observed an inverse correlation between AMD and cooking oils harboring a beneficial omega-3 fatty acid profile.

Valid statistical inference methods for a case-control study with missing data.

PubMed

Tian, Guo-Liang; Zhang, Chi; Jiang, Xuejun

2018-04-01

The main objective of this paper is to derive the valid sampling distribution of the observed counts in a case-control study with missing data under the assumption of missing at random by employing the conditional sampling method and the mechanism augmentation method. The proposed sampling distribution, called the case-control sampling distribution, can be used to calculate the standard errors of the maximum likelihood estimates of parameters via the Fisher information matrix and to generate independent samples for constructing small-sample bootstrap confidence intervals. Theoretical comparisons of the new case-control sampling distribution with two existing sampling distributions exhibit a large difference. Simulations are conducted to investigate the influence of the three different sampling distributions on statistical inferences. One finding is that the conclusion by the Wald test for testing independency under the two existing sampling distributions could be completely different (even contradictory) from the Wald test for testing the equality of the success probabilities in control/case groups under the proposed distribution. A real cervical cancer data set is used to illustrate the proposed statistical methods.

Lack of association between migraine headache and patent foramen ovale: results of a case-control study.

PubMed

Garg, Pallav; Servoss, Stephen J; Wu, Justina C; Bajwa, Zahid H; Selim, Magdy H; Dineen, Alexis; Kuntz, Richard E; Cook, E Francis; Mauri, Laura

2010-03-30

Clinical observations of migraine headache symptoms in patients with a patent foramen ovale (PFO), both of which conditions are highly prevalent, have raised the question of a possible pathophysiological relationship. We sought to evaluate the assumption of an association between migraine headaches and the presence of PFO by use of a large case-control study. We conducted a case-control study to assess the prevalence of PFO in subjects with and without migraine. Case subjects were those with a history of migraine (diagnosed by neurologists at a specialty academic headache clinic). Control subjects were healthy volunteers without migraine 1:1 matched on the basis of age and sex with case subjects. Presence of PFO was determined by transthoracic echocardiogram with second harmonic imaging and transcranial Doppler ultrasonography during a standardized procedure of infused agitated saline contrast with or without Valsalva maneuver and a review of the results by experts blinded to case-control status. PFO was considered present if both studies were positive. Odds ratios were calculated with conditional logistic regression in the matched cohort (n=288). In the matched analysis, the prevalence of PFO was similar in case and control subjects (26.4% versus 25.7%; odds ratio 1.04, 95% confidence interval 0.62 to 1.74, P=0.90). There was no difference in PFO prevalence in those with migraine with aura and those without (26.8% versus 26.1%; odds ratio 1.03, 95% confidence interval 0.48 to 2.21, P=0.93). We found no association between migraine headaches and the presence of PFO in this large case-control study.

Risk of intracerebral hemorrhage associated with phenprocoumon exposure: a nested case-control study in a large population-based German database.

PubMed

Behr, Sigrid; Andersohn, Frank; Garbe, Edeltraut

2010-07-01

Intracerebral hemorrhage (ICH) is the most serious complication of oral anticoagulation. This study investigated the risk of ICH for phenprocoumon which is the most widely used oral anticoagulant in Germany. We conducted a nested case-control study in a cohort of 13.4 million insurants of 4 German statutory health insurances (SHIs) who were continuously enrolled for 6 months prior to cohort entry. Cases were patients hospitalized for ICH. Ten controls were matched to each case by SHI, birth year, and sex using incidence density sampling. Rate ratios (RR) of ICH for current phenprocoumon use as compared to non-use were estimated from odds ratios calculated by conditional logistic regression analyses considering multiple risk factors. Analysis of the full cohort revealed a strong increase in incidence of ICH with increasing age. In the nested case-control study including 8138 cases of ICH and 81,373 matched controls, we observed an increased risk of ICH for current phenprocoumon exposure that varied with age. The phenprocoumon-associated risk of ICH was lower in older age groups with RRs from 4.20 (95% confidence interval (CI) 2.44-7.21) for phenprocoumon users less than 55 years of age to 2.43 (95%CI, 1.81-3.27) for those older than 85 years. Our study confirmed known risk factors of ICH. Phenprocoumon exposure was associated with an increased risk of ICH. The interaction of risk for phenprocoumon with age was unexpected and needs further study. (c) 2010 John Wiley & Sons, Ltd.

Pilot case-control study of paediatric falls from windows.

PubMed

Johnston, Brian D; Quistberg, D Alexander; Shandro, Jamie R; Partridge, Rebecca L; Song, Hyun Rae; Ebel, Beth E

2011-12-01

Unintentional falls from windows are an important cause of paediatric morbidity. There have been no controlled studies to identify modifiable environmental risk factors for window falls in young children. The authors have piloted a case-control study to test procedures for case identification, subject enrolment, and environmental data collection. Case windows were identified when a child 0-9 years old presented for care after a fall from that window. Control windows were identified (1) from the child's home and (2) from the home of an age- and gender-matched child seeking care for an injury diagnosis not related to a window fall. Study staff visited enrolled homes to collect window measurements and conduct window screen performance tests. The authors enrolled and collected data on 18 case windows, 18 in-home controls, and 14 matched community controls. Six potential community controls were contacted for every one enrolled. Families who completed the home visit viewed study procedures positively. Case windows were more likely than community controls to be horizontal sliders (100% vs 50%), to have deeper sills (6.28 vs 4.31 inches), to be higher above the exterior surface (183 vs 82 inches), and to have screens that failed below a threshold derived from the static pressure of a 3-year-old leaning against the mesh (60.0% vs 16.7%). Case windows varied very little from in-home controls. Case-control methodology can be used to study risk factors for paediatric falls from windows. Recruitment of community controls is challenging but essential, because in-home controls tend to be over-matched on important variables. A home visit allows direct measurement of window type, height, sill depth, and screen performance. These variables should all be investigated in subsequent, larger studies covering major housing markets.

Nested case-control studies: should one break the matching?

PubMed

Borgan, Ørnulf; Keogh, Ruth

2015-10-01

In a nested case-control study, controls are selected for each case from the individuals who are at risk at the time at which the case occurs. We say that the controls are matched on study time. To adjust for possible confounding, it is common to match on other variables as well. The standard analysis of nested case-control data is based on a partial likelihood which compares the covariates of each case to those of its matched controls. It has been suggested that one may break the matching of nested case-control data and analyse them as case-cohort data using an inverse probability weighted (IPW) pseudo likelihood. Further, when some covariates are available for all individuals in the cohort, multiple imputation (MI) makes it possible to use all available data in the cohort. In the paper we review the standard method and the IPW and MI approaches, and compare their performance using simulations that cover a range of scenarios, including one and two endpoints.

25-hydroxyvitamin D and breast cancer, colorectal cancer, and colorectal adenomas: case-control versus nested case-control studies.

PubMed

Grant, William B

2015-02-01

Existing literature includes concerns regarding reliability of case-control studies of breast cancer incidence with respect to 25-hydroxyvitamin D (25(OH)D) concentrations. For breast cancer, only case-control studies consistently find inverse correlations between 25(OH)D and breast cancer. However, for colorectal cancer, nested case-control studies find significant inverse correlations with respect to 25(OH)D concentrations at baseline for mean follow-up times of 7 years. This is a review of results currently existing in literature. I provide evidence that 25(OH)D concentration values are only useful for short follow-up times for breast cancer since it develops rapidly. To support the robust nature of breast cancer case-control studies, I show that results from 11 studies from seven countries align in a robust power-law fit to the odds ratio versus mean 25(OH)D concentrations. Case-control studies of breast cancer incidence rates provide reliable results. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Analgesics use and ESRD in younger age: a case-control study

PubMed Central

van der Woude, Fokke J; Heinemann, Lothar AJ; Graf, Helmut; Lewis, Michael; Moehner, Sabine; Assmann, Anita; Kühl-Habich, Doerthe

2007-01-01

Background An ad hoc peer-review committee was jointly appointed by Drug Authorities and Industry in Germany, Austria and Switzerland in 1999/2000 to review the evidence for a causal relation between phenacetin-free analgesics and nephropathy. The committee found the evidence as inconclusive and requested a new case-control study of adequate design. Methods We performed a population-based case-control study with incident cases of end-stage renal disease (ESRD) under the age of 50 years and four age and sex-matched neighborhood controls in 170 dialysis centers (153 in Germany, and 17 in Austria) from January 1, 2001 to December 31, 2004. Data on lifetime medical history, risk factors, treatment, job exposure and intake of analgesics were obtained in a standardized face-to-face interview using memory aids to enhance accuracy. Study design, study performance, analysis plan, and study report were approved by an independent international advisory committee and by the Drug Authorities involved. Unconditional logistic regression analyses were performed. Results The analysis included 907 cases and 3,622 controls who had never used phenacetin-containing analgesics in their lifetime. The use of high cumulative lifetime dose (3rd tertile) of analgesics in the period up to five years before dialysis was not associated with later ESRD. Adjusted odds ratios with 95% confidence intervals were 0.8 (0.7 – 1.0) and 1.0 (0.8 – 1.3) for ever- compared with no or low use and high use compared with low use, respectively. The same results were found for all analgesics and for mono-, and combination preparations with and without caffeine. No increased risk was shown in analyses stratifying for dose and duration. Dose-response analyses showed that analgesic use was not associated with an increased risk for ESRD up to 3.5 kg cumulative lifetime dose (98 % of the cases with ESRD). While the large subgroup of users with a lifetime dose up to 0.5 kg (278 cases and 1365 controls) showed a

Association between bullous pemphigoid and neurologic diseases: a case-control study.

PubMed

Casas-de-la-Asunción, E; Ruano-Ruiz, J; Rodríguez-Martín, A M; Vélez García-Nieto, A; Moreno-Giménez, J C

2014-11-01

In the past 10 years, bullous pemphigoid has been associated with other comorbidities and neurologic and psychiatric conditions in particular. Case series, small case-control studies, and large population-based studies in different Asian populations, mainland Europe, and the United Kingdom have confirmed this association. However, no data are available for the Spanish population. This was an observational, retrospective, case-control study with 1:2 matching. Fifty-four patients with bullous pemphigoid were selected. We compared the percentage of patients in each group with concurrent neurologic conditions, ischemic heart disease, diabetes, chronic obstructive pulmonary disease, and solid tumors using univariate logistic regression. An association model was constructed with conditional multiple logistic regression. The case group had a significantly higher percentage of patients with cerebrovascular accident and/or transient ischemic attack (odds ratio [OR], 3.06; 95% CI, 1.19-7.87], dementia (OR, 5.52; 95% CI, 2.19-13.93), and Parkinson disease (OR, 5; 95% CI, 1.57-15.94). A significantly higher percentage of cases had neurologic conditions (OR, 6.34; 95% CI, 2.89-13.91). Dementia and Parkinson disease were independently associated with bullous pemphigoid in the multivariate analysis. Patients with bullous pemphigoid have a higher frequency of neurologic conditions. Copyright © 2013 Elsevier España, S.L.U. and AEDV. All rights reserved.

Role of matching in case-control studies of antimicrobial resistance.

PubMed

Cerceo, Elizabeth; Lautenbach, Ebbing; Linkin, Darren R; Bilker, Warren B; Lee, Ingi

2009-05-01

Of 57 case-control studies of antimicrobial resistance, matching was used in 23 (40%). Matched variables differed substantially across studies. Of these 23 matched case-control studies, 12 (52%) justified the use of matching, and 9 (39%) noted the strengths or limitations of this approach. Analysis that accounted for matching was performed in only 52% of the case-control studies.

Environmental and occupational risk factors for progressive supranuclear palsy: Case-control study.

PubMed

Litvan, Irene; Lees, Peter S J; Cunningham, Christopher R; Rai, Shesh N; Cambon, Alexander C; Standaert, David G; Marras, Connie; Juncos, Jorge; Riley, David; Reich, Stephen; Hall, Deborah; Kluger, Benzi; Bordelon, Yvette; Shprecher, David R

2016-05-01

The cause of progressive supranuclear palsy (PSP) is largely unknown. Based on evidence for impaired mitochondrial activity in PSP, we hypothesized that the disease may be related to exposure to environmental toxins, some of which are mitochondrial inhibitors. This multicenter case-control study included 284 incident PSP cases of 350 cases and 284 age-, sex-, and race-matched controls primarily from the same geographical areas. All subjects were administered standardized interviews to obtain data on demographics, residential history, and lifetime occupational history. An industrial hygienist and a toxicologist unaware of case status assessed occupational histories to estimate past exposure to metals, pesticides, organic solvents, and other chemicals. Cases and controls were similar on demographic factors. In unadjusted analyses, PSP was associated with lower education, lower income, more smoking pack-years, more years of drinking well water, more years living on a farm, more years living 1 mile from an agricultural region, more transportation jobs, and more jobs with exposure to metals in general. However, in adjusted models, only more years of drinking well water was significantly associated with PSP. There was an inverse association with having a college degree. We did not find evidence for a specific causative chemical exposure; higher number of years of drinking well water is a risk factor for PSP. This result remained significant after adjusting for income, smoking, education and occupational exposures. This is the first case-control study to demonstrate PSP is associated with environmental factors. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

Birth outcomes of male and female patients with infantile hypertrophic pyloric stenosis--a population-based case-control study.

PubMed

Vermes, Gabor; Mátrai, Ákos; Czeizel, Andrew E; Ács, Nándor

2016-01-01

Most of the patients are affected by isolated infantile hypertrophic pyloric stenosis (IHPS) beyond the polygenic predisposition, the other factors in the multifactorial etiology are largely unknown. The main characteristic of IHPS is the robust male predominance, thus the aim of this study was to analyze birth outcomes in males and females whether they are different or not. The study samples included 241 cases with IHPS, 357 matched, and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. The findings of this case-control study confirmed the well-known strong male excess (85.5%). The mean gestational age was somewhat longer and it is associated with a lower rate of preterm births. Mean birth weight did not show significant differences among the study groups, but the rate of low birthweight was higher in cases with IHPS. However, these differences were found only in males. Thus, intrauterine fetal growth restriction is characteristic only for male cases with IHPS. Our study confirmed the well-known obvious male excess of cases with IHPS, but our findings suggest some differences in birth outcomes of male and female cases. Male cases with IHPS had intrauterine fetal growth restriction while females did not. These data may indicate some differences in the pathogenesis of IHPS in males and females.

Two-tier Haddon matrix approach to fault analysis of accidents and cybernetic search for relationship to effect operational control: a case study at a large construction site.

PubMed

Mazumdar, Atmadeep; Sen, Krishna Nirmalya; Lahiri, Balendra Nath

2007-01-01

The Haddon matrix is a potential tool for recognizing hazards in any operating engineering system. This paper presents a case study of operational hazards at a large construction site. The fish bone structure helps to visualize and relate the chain of events, which led to the failure of the system. The two-tier Haddon matrix approach helps to analyze the problem and subsequently prescribes preventive steps. The cybernetic approach has been undertaken to establish the relationship among event variables and to identify the ones with most potential. Those event variables in this case study, based on the cybernetic concepts like control responsiveness and controllability salience, are (a) uncontrolled swing of sheet contributing to energy, (b) slippage of sheet from anchor, (c) restricted longitudinal and transverse swing or rotation about the suspension, (d) guilt or uncertainty of the crane driver, (e) safe working practices and environment.

Mobile phone use and the risk for malignant brain tumors: a case-control study on deceased cases and controls.

PubMed

Hardell, Lennart; Carlberg, Michael; Hansson Mild, Kjell

2010-08-01

We investigated the use of mobile or cordless phones and the risk for malignant brain tumors in a group of deceased cases. Most previous studies have either left out deceased cases of brain tumors or matched them to living controls and therefore a study matching deceased cases to deceased controls is warranted. Recall error is one issue since it has been claimed that increased risks reported in some studies could be due to cases blaming mobile phones as a cause of the disease. This should be of less importance for deceased cases and if cancer controls are used. In this study brain tumor cases aged 20-80 years diagnosed during 1997-2003 that had died before inclusion in our previous studies on the same topic were included. Two control groups were used: one with controls that had died from another type of cancer than brain tumor and one with controls that had died from other diseases. Exposure was assessed by a questionnaire sent to the next-of-kin for both cases and controls. Replies were obtained for 346 (75%) cases, 343 (74%) cancer controls and 276 (60%) controls with other diseases. Use of mobile phones gave an increased risk, highest in the >10 years' latency group yielding odds ratio (OR) = 2.4, and 95% confidence interval (CI) = 1.4-4.1. The risk increased with cumulative number of lifetime hours for use, and was highest in the >2,000 h group (OR = 3.4, 95% CI = 1.6-7.1). No clear association was found for use of cordless phones, although OR = 1.7, 95% CI = 0.8-3.4 was found in the group with >2,000 h of cumulative use. This investigation confirmed our previous results of an association between mobile phone use and malignant brain tumors. Copyright 2010 S. Karger AG, Basel.

Tularemia Outbreak Investigation in Kosovo: Case Control and Environmental Studies

PubMed Central

Dedushaj, Isuf; Gjini, Ardiana; Jorgensen, Tine Rikke; Cotter, Benvon; Lieftucht, Alfons; D’Ancona, Fortunato; Dennis, David T.; Kosoy, Michael A.; Mulliqi-Osmani, Gjyle; Grunow, Roland; Kalaveshi, Ariana; Gashi, Luljeta; Humolli, Isme

2002-01-01

A large outbreak of tularemia occurred in Kosovo in the early postwar period, 1999-2000. Epidemiologic and environmental investigations were conducted to identify sources of infection, modes of transmission, and household risk factors. Case and control status was verified by enzyme-linked immunosorbent assay, Western blot, and microagglutination assay. A total of 327 serologically confirmed cases of tularemia pharyngitis and cervical lymphadenitis were identified in 21 of 29 Kosovo municipalities. Matched analysis of 46 case households and 76 control households suggested that infection was transmitted through contaminated food or water and that the source of infection was rodents. Environmental circumstances in war-torn Kosovo led to epizootic rodent tularemia and its spread to resettled rural populations living under circumstances of substandard housing, hygiene, and sanitation. PMID:11749751

Population versus hospital controls for case-control studies on cancers in Chinese hospitals

PubMed Central

2011-01-01

Background Correct control selection is crucial to the internal validity of case-control studies. Little information exists on differences between population and hospital controls in case-control studies on cancers in Chinese hospital setting. Methods We conducted three parallel case-control studies on leukemia, breast and colorectal cancers in China between 2009 and 2010, using population and hospital controls to separately match 540 incident cases by age, gender and residency at a 1:1 ratio. Demographic and lifestyle factors were measured using a validated questionnaire in face-to-face interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were obtained using conditional logistic regression analyses. Results The two control groups had closely similar exposure distributions of 15 out of 16 factors, with the only exception being that hospital controls were less likely to have a BMI ≥ 25 (OR = 0.71, 95% CI: 0.54, 0.93). For exposure of green tea drinking, the adjusted ORs (95% CIs) comparing green tealeaves intake ≥ 1000 grams annually with non-drinkers were 0.51 (0.31, 0.83) and 0.21 (0.27, 0.74) for three cancers combined, 0.06 (0.01, 0.61) and 0.07 (0.01, 0.47) for breast cancer, 0.52 (0.29, 0.94) and 0.45 (0.25, 0.82) for colorectal cancer, 0.65 (0.08, 5.63) and 0.57 (0.07, 4.79) for leukemia using hospital and population controls respectively. Conclusions The study found that hospital controls were comparable with population controls for most demographic characteristics and lifestyle factors measured, but there was a slight difference between the two control groups. Hospital outpatients provide a satisfactory control group in hospital-based case-control study in the Chinese hospital setting. PMID:22171783

Population versus hospital controls for case-control studies on cancers in Chinese hospitals.

PubMed

Li, Lin; Zhang, Min; Holman, D'Arcy

2011-12-15

Correct control selection is crucial to the internal validity of case-control studies. Little information exists on differences between population and hospital controls in case-control studies on cancers in Chinese hospital setting. We conducted three parallel case-control studies on leukemia, breast and colorectal cancers in China between 2009 and 2010, using population and hospital controls to separately match 540 incident cases by age, gender and residency at a 1:1 ratio. Demographic and lifestyle factors were measured using a validated questionnaire in face-to-face interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were obtained using conditional logistic regression analyses. The two control groups had closely similar exposure distributions of 15 out of 16 factors, with the only exception being that hospital controls were less likely to have a BMI ≥ 25 (OR = 0.71, 95% CI: 0.54, 0.93). For exposure of green tea drinking, the adjusted ORs (95% CIs) comparing green tealeaves intake ≥ 1000 grams annually with non-drinkers were 0.51 (0.31, 0.83) and 0.21 (0.27, 0.74) for three cancers combined, 0.06 (0.01, 0.61) and 0.07 (0.01, 0.47) for breast cancer, 0.52 (0.29, 0.94) and 0.45 (0.25, 0.82) for colorectal cancer, 0.65 (0.08, 5.63) and 0.57 (0.07, 4.79) for leukemia using hospital and population controls respectively. The study found that hospital controls were comparable with population controls for most demographic characteristics and lifestyle factors measured, but there was a slight difference between the two control groups. Hospital outpatients provide a satisfactory control group in hospital-based case-control study in the Chinese hospital setting.

The Effectiveness of Lecture-Integrated, Web-Supported Case Studies in Large Group Teaching

ERIC Educational Resources Information Center

Azzawi, May; Dawson, Maureen M.

2007-01-01

The effectiveness of lecture-integrated and web-supported case studies in supporting a large and academically diverse group of undergraduate students was evaluated in the present study. Case studies and resource (web)-based learning were incorporated as two complementary interactive learning strategies into the traditional curriculum. A truncated…

Campylobacteriosis in New Zealand: results of a case-control study.

PubMed Central

Eberhart-Phillips, J; Walker, N; Garrett, N; Bell, D; Sinclair, D; Rainger, W; Bates, M

1997-01-01

STUDY OBJECTIVE: To identify and assess the contributions of major risk factors for campylobacteriosis in New Zealand. DESIGN: Case-control study. Home interviews were conducted over nine months using a standardised questionnaire to assess recent food consumption and other exposures. SETTING: Four centres in New Zealand with high notification rates of campylobacter infections--Auckland, Hamilton, Wellington, and Christchurch. PARTICIPANTS: Case patients were 621 people notified between 1 June 1994 and 28 February 1995 as having campylobacter infection. Control subjects were selected randomly from telephone directories, and were matched 1:1 with case patients in relation to sex, age group, and home telephone prefix. RESULTS: Risk of campylobacteriosis was strongly associated with recent consumption of raw or undercooked chicken (matched odds ratio 4.52, 95% confidence interval 2.88, 7.10). There was also an increased risk with chicken eaten in restaurants (matched odds ratio 3.85; 2.52, 5.88). Recent consumption of baked or roasted chicken seemed to be protective. Campylobacteriosis was also associated with recent overseas travel, rainwater as a source of water at home, consumption of raw dairy products, and contact with puppies and cattle, particularly calves. CONCLUSIONS: Improperly cooked chicken seems to be associated with a large proportion of campylobacteriosis in New Zealand. Thorough cooking of chicken in homes and restaurants could reduce considerably the incidence of this disease. PMID:9519133

VIM-positive Pseudomonas aeruginosa in a large tertiary care hospital: matched case-control studies and a network analysis.

PubMed

Voor In 't Holt, Anne F; Severin, Juliëtte A; Hagenaars, Margot B H; de Goeij, Inge; Gommers, Diederik; Vos, Margreet C

2018-01-01

Emergence of multidrug-resistant Pseudomonas aeruginosa is of global concern. We aimed to identify epidemiological relationships, the most common way of transmission, and risk factors for presence of Verona Integron-encoded Metallo-β-lactamase (VIM)-positive P. aeruginosa (VIM-PA). We conducted a network analysis and matched case-control studies (1:2:2). Controls were hospital-based and matched with cases for ward, day of admission (control group 1 and 2) and time between admission and the identification of VIM-PA (control group 1). The network was visualized using Cytoscape, and risk factors were determined using conditional logistic regression. Between August 2003 and April 2015, 144 case patients and 576 control patients were recruited. We identified 307 relationships in 114 out of these 144 patients, with most relationships (84.7%) identified at the same department < 3 months after a previous case patient was discharged. In the multivariable model, having undergone ≥1 gastroscopy (odds ratio [OR] = 4.40, 95% confidence interval [CI] = 2.00 to 9.65 and OR = 2.47; 95% CI = 1.12 to 5.49), > 10 day use of selective digestive tract decontamination (SDD) (OR = 2.97; 95% CI = 1.02 to 8.68 and OR = 4.61; 95% CI = 1.22 to 17.37), and use of quinolones (OR = 3.29; 95% CI = 1.34 to 8.10 and OR = 3.95; 95% CI = 1.13 to 13.83 and OR = 4.47; 95% CI = 1.75 to 11.43) were identified as risk factors when using both control groups. The network analysis indicated that the majority of transmissions occurred on the wards, but through unidentified and presumably persistent sources, which are most likely in the innate hospital environment. Previous use of certain antibiotic regimens made patients prone to VIM-PA carriage. Additionally, gastroscopy could be considered as a high-risk procedure in patients with risk factors. Our results add to the growing body of evidence that infection control measures targeting VIM-PA should be focused on reducing

Case-control vaccine effectiveness studies: Data collection, analysis and reporting results.

PubMed

Verani, Jennifer R; Baqui, Abdullah H; Broome, Claire V; Cherian, Thomas; Cohen, Cheryl; Farrar, Jennifer L; Feikin, Daniel R; Groome, Michelle J; Hajjeh, Rana A; Johnson, Hope L; Madhi, Shabir A; Mulholland, Kim; O'Brien, Katherine L; Parashar, Umesh D; Patel, Manish M; Rodrigues, Laura C; Santosham, Mathuram; Scott, J Anthony; Smith, Peter G; Sommerfelt, Halvor; Tate, Jacqueline E; Victor, J Chris; Whitney, Cynthia G; Zaidi, Anita K; Zell, Elizabeth R

2017-06-05

The case-control methodology is frequently used to evaluate vaccine effectiveness post-licensure. The results of such studies provide important insight into the level of protection afforded by vaccines in a 'real world' context, and are commonly used to guide vaccine policy decisions. However, the potential for bias and confounding are important limitations to this method, and the results of a poorly conducted or incorrectly interpreted case-control study can mislead policies. In 2012, a group of experts met to review recent experience with case-control studies evaluating vaccine effectiveness; we summarize the recommendations of that group regarding best practices for data collection, analysis, and presentation of the results of case-control vaccine effectiveness studies. Vaccination status is the primary exposure of interest, but can be challenging to assess accurately and with minimal bias. Investigators should understand factors associated with vaccination as well as the availability of documented vaccination status in the study context; case-control studies may not be a valid method for evaluating vaccine effectiveness in settings where many children lack a documented immunization history. To avoid bias, it is essential to use the same methods and effort gathering vaccination data from cases and controls. Variables that may confound the association between illness and vaccination are also important to capture as completely as possible, and where relevant, adjust for in the analysis according to the analytic plan. In presenting results from case-control vaccine effectiveness studies, investigators should describe enrollment among eligible cases and controls as well as the proportion with no documented vaccine history. Emphasis should be placed on confidence intervals, rather than point estimates, of vaccine effectiveness. Case-control studies are a useful approach for evaluating vaccine effectiveness; however careful attention must be paid to the collection

Case-control study on uveal melanoma (RIFA): rational and design

PubMed Central

Schmidt-Pokrzywniak, Andrea; Jöckel, Karl-Heinz; Bornfeld, Norbert; Stang, Andreas

2004-01-01

Background Although a rare disease, uveal melanoma is the most common primary intraocular malignancy in adults, with an incidence rate of up to 1.0 per 100,000 persons per year in Europe. Only a few consistent risk factors have been identified for this disease. We present the study design of an ongoing incident case-control study on uveal melanoma (acronym: RIFA study) that focuses on radiofrequency radiation as transmitted by radio sets and wireless telephones, occupational risk factors, phenotypical characteristics, and UV radiation. Methods/Design We conduct a case-control study to identify the role of different exposures in the development of uveal melanoma. The cases of uveal melanoma were identified at the Division of Ophthalmology, University of Essen, a referral centre for tumours of the eye. We recruit three control groups: population controls, controls sampled from those ophthalmologists who referred cases to the Division of Ophthalmology, University of Duisburg-Essen, and sibling controls. For each case the controls are matched on sex and age (five year groups), except for sibling controls. The data are collected from the study participants by short self-administered questionnaire and by telephone interview. During and at the end of the field phase, the data are quality-checked. To estimate the effect of exposures on uveal melanoma risk, we will use conditional logistic regression that accounts for the matching factors and allows to control for potential confounding. PMID:15318944

Three ADIPOR1 Polymorphisms and Cancer Risk: A Meta-Analysis of Case-Control Studies.

PubMed

Ye, Jiaxiang; Jiang, Li; Wu, Changliang; Liu, Aiqun; Mao, Sufei; Ge, Lianying

2015-01-01

Studies have come to conflicting conclusions about whether polymorphisms in the adiponectin receptor 1 gene (ADIPOR1) are associated with cancer risk. To help resolve this question, we meta-analyzed case-control studies in the literature. PubMed, EMBASE, Cochrane Library, the Chinese Biological Medical Database and the Chinese National Knowledge Infrastructure Database were systematically searched to identify all case-control studies published through February 2015 examining any ADIPOR1 polymorphisms and risk of any type of cancer. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated. A total of 13 case-control studies involving 5,750 cases and 6,762 controls were analyzed. Analysis of the entire study population revealed a significant association between rs1342387(G/A) and overall cancer risk using a homozygous model (OR 0.82, 95%CI 0.72 to 0.94), heterozygous model (OR 0.84, 95%CI 0.76 to 0.93), dominant model (OR 0.85, 95%CI 0.75 to 0.97) and allele contrast model (OR 0.88, 95%CI 0.80 to 0.97). However, subgroup analysis showed that this association was significant only for Asians in the case of colorectal cancer. No significant associations were found between rs12733285(C/T) or rs7539542(C/G) and cancer risk, either in analyses of the entire study population or in analyses of subgroups. Our meta-analysis suggests that the ADIPOR1 rs1342387(G/A) polymorphism, but not rs12733285(C/T) or rs7539542(C/G), may be associated with cancer risk, especially risk of colorectal cancer in Asians. Large, well-designed studies are needed to verify our findings.

Association of common polymorphisms in GLUT9 gene with gout but not with coronary artery disease in a large case-control study.

PubMed

Stark, Klaus; Reinhard, Wibke; Neureuther, Katharina; Wiedmann, Silke; Sedlacek, Kamil; Baessler, Andrea; Fischer, Marcus; Weber, Stefan; Kaess, Bernhard; Erdmann, Jeanette; Schunkert, Heribert; Hengstenberg, Christian

2008-04-09

Serum uric acid (UA) levels have recently been shown to be genetically influenced by common polymorphisms in the GLUT9 gene in two genome-wide association analyses of Italian and British populations. Elevated serum UA levels are often found in conjunction with the metabolic syndrome. Hyperuricemia is the major risk factor for gout and has been associated with increased cardiovascular morbidity and mortality. The aim of the present study was to further elucidate the association of polymorphisms in GLUT9 with gout and coronary artery disease (CAD) or myocardial infarction (MI). To test our hypotheses, we performed two large case-control association analyses of individuals from the German MI Family Study. First, 665 patients with gout and 665 healthy controls, which were carefully matched for age and gender, were genotyped for four single nucleotide polymorphisms (SNPs) within or near the GLUT9 gene. All four SNPs demonstrated highly significant association with gout. SNP rs6855911, located within intron 7 of GLUT9, showed the strongest signal with a protective effect of the minor allele with an allelic odds ratio of 0.62 (95% confidence interval 0.52-0.75; p = 3.2*10(-7)). Importantly, this finding was not influenced by adjustment for components of the metabolic syndrome or intake of diuretics. Secondly, 1,473 cases with severe CAD or MI and 1,241 healthy controls were tested for the same four GLUT9 SNPs. The analyses revealed, however, no significant association with CAD or with MI. Additional screening of genome-wide association data sets showed no signal for CAD or MI within the GLUT9 gene region. Thus, our results provide compelling evidence that common genetic variations within the GLUT9 gene strongly influence the risk for gout but are unlikely to have a major effect on CAD or MI in a German population.

Optimization under variability and uncertainty: a case study for NOx emissions control for a gasification system.

PubMed

Chen, Jianjun; Frey, H Christopher

2004-12-15

Methods for optimization of process technologies considering the distinction between variability and uncertainty are developed and applied to case studies of NOx control for Integrated Gasification Combined Cycle systems. Existing methods of stochastic optimization (SO) and stochastic programming (SP) are demonstrated. A comparison of SO and SP results provides the value of collecting additional information to reduce uncertainty. For example, an expected annual benefit of 240,000 dollars is estimated if uncertainty can be reduced before a final design is chosen. SO and SP are typically applied to uncertainty. However, when applied to variability, the benefit of dynamic process control is obtained. For example, an annual savings of 1 million dollars could be achieved if the system is adjusted to changes in process conditions. When variability and uncertainty are treated distinctively, a coupled stochastic optimization and programming method and a two-dimensional stochastic programming method are demonstrated via a case study. For the case study, the mean annual benefit of dynamic process control is estimated to be 700,000 dollars, with a 95% confidence range of 500,000 dollars to 940,000 dollars. These methods are expected to be of greatest utility for problems involving a large commitment of resources, for which small differences in designs can produce large cost savings.

Shape determination and control for large space structures

NASA Technical Reports Server (NTRS)

Weeks, C. J.

1981-01-01

An integral operator approach is used to derive solutions to static shape determination and control problems associated with large space structures. Problem assumptions include a linear self-adjoint system model, observations and control forces at discrete points, and performance criteria for the comparison of estimates or control forms. Results are illustrated by simulations in the one dimensional case with a flexible beam model, and in the multidimensional case with a finite model of a large space antenna. Modal expansions for terms in the solution algorithms are presented, using modes from the static or associated dynamic mode. These expansions provide approximated solutions in the event that a used form analytical solution to the system boundary value problem is not available.

A large case-control study reveals a positive association between bisphosphonate use and delayed dental healing and osteonecrosis of the jaw.

PubMed

Borromeo, Gelsomina L; Brand, Caroline; Clement, John G; McCullough, Michael; Crighton, Lisa; Hepworth, Graham; Wark, John D

2014-06-01

This study sought to investigate, using a case-control study design, the association between bisphosphonate therapy and delayed dental healing and osteonecrosis of the jaw. Identification of potential cases of delayed dental healing was by consecutive screening of Specialist Oral and Maxillofacial and Special Needs Dentist clinic records for patients aged older than 50 years, during a 6-month window, in Victoria, Australia. Cases were confirmed by a case adjudication panel blinded to bisphosphonate status. Cases associated with malignancy or local radiotherapy were excluded. Controls were matched for age, sex, and source of dental referral (1:4, n = 160 controls). Variables of interest were dental precipitants, dental clinic type, smoking history, and medical comorbidities. A total of 4212 of 22,358 patients met inclusion criteria, of which 69 were potential cases with 40 (0.95%) confirmed cases. The odds ratio (OR) for developing delayed dental healing when taking an oral bisphosphonate was 13.1 (95% confidence interval [CI] 4.4 to 39.3; p < 0.001). There were no cases associated with intravenous bisphosphonate use. There was some evidence of an interaction with age, sex, and clinic type. When adjusted for smoking, the estimated odds ratio was 11.6 (95% CI 1.9 to 69.4; p = 0.01). There was an association between having another illness and delayed dental healing (OR = 2.3; 95% CI 1.0 to 5.2). A dental precipitant was present in 39 of 40 (97.5%) delayed dental healing cases. An important association between bisphosphonate use and delayed dental healing in the setting of benign bone disease, predominately in individuals with a dental precipitant, has been demonstrated. © 2014 American Society for Bone and Mineral Research.

Sweets, sweetened beverages, and risk of pancreatic cancer in a large population-based case-control study.

PubMed

Chan, June M; Wang, Furong; Holly, Elizabeth A

2009-08-01

We examined the associations between sweets, sweetened and unsweetened beverages, and sugars and pancreatic cancer risk. We conducted a population-based case-control study (532 cases, 1,701 controls) and used multivariate logistic regression models to calculate odds ratios (OR) and 95% confidence intervals (CI). Because associations were often different by sex, we present results for men and women combined and separately. Among men, greater intakes of total and specific sweets were associated with pancreatic cancer risk (total sweets: OR = 1.9, 95% CI: 1.0, 3.6; sweet condiments: OR = 1.9, 95% CI: 1.2, 3.1; chocolate candy: OR = 2.4, 95% CI: 1.1, 5.0; other mixed candy bars: OR = 3.3, 95% CI: 1.5, 7.3 for 1 + servings/day versus none/rarely). Sweets were not consistently associated with risk among women. Sweetened beverages were not associated with increased pancreatic cancer risk. In contrast, low-calorie soft drinks were associated with increased risk among men only; while other low-/non-caloric beverages (e.g., coffee, tea, and water) were unassociated with risk. Of the three sugars assessed (lactose, fructose, and sucrose), only the milk sugar lactose was associated with pancreatic cancer risk (OR = 2.0, 95% CI: 1.5, 2.7 comparing extreme quartiles). These results provide limited support for the hypothesis that sweets or sugars increase pancreatic cancer risk.

Lung Cancer and Occupation in a Population-based Case-Control Study

PubMed Central

Consonni, Dario; De Matteis, Sara; Lubin, Jay H.; Wacholder, Sholom; Tucker, Margaret; Pesatori, Angela Cecilia; Caporaso, Neil E.; Bertazzi, Pier Alberto; Landi, Maria Teresa

2010-01-01

The authors examined the relation between occupation and lung cancer in the large, population-based Environment And Genetics in Lung cancer Etiology (EAGLE) case-control study. In 2002–2005 in the Lombardy region of northern Italy, 2,100 incident lung cancer cases and 2,120 randomly selected population controls were enrolled. Lifetime occupational histories (industry and job title) were coded by using standard international classifications and were translated into occupations known (list A) or suspected (list B) to be associated with lung cancer. Smoking-adjusted odds ratios and 95% confidence intervals were calculated with logistic regression. For men, an increased risk was found for list A (177 exposed cases and 100 controls; odds ratio = 1.74, 95% confidence interval: 1.27, 2.38) and most occupations therein. No overall excess was found for list B with the exception of filling station attendants and bus and truck drivers (men) and launderers and dry cleaners (women). The authors estimated that 4.9% (95% confidence interval: 2.0, 7.8) of lung cancers in men were attributable to occupation. Among those in other occupations, risk excesses were found for metal workers, barbers and hairdressers, and other motor vehicle drivers. These results indicate that past exposure to occupational carcinogens remains an important determinant of lung cancer occurrence. PMID:20047975

Campylobacteriosis in New Zealand: results of a case-control study.

PubMed

Eberhart-Phillips, J; Walker, N; Garrett, N; Bell, D; Sinclair, D; Rainger, W; Bates, M

1997-12-01

To identify and assess the contributions of major risk factors for campylobacteriosis in New Zealand. Case-control study. Home interviews were conducted over nine months using a standardised questionnaire to assess recent food consumption and other exposures. Four centres in New Zealand with high notification rates of campylobacter infections--Auckland, Hamilton, Wellington, and Christchurch. Case patients were 621 people notified between 1 June 1994 and 28 February 1995 as having campylobacter infection. Control subjects were selected randomly from telephone directories, and were matched 1:1 with case patients in relation to sex, age group, and home telephone prefix. Risk of campylobacteriosis was strongly associated with recent consumption of raw or undercooked chicken (matched odds ratio 4.52, 95% confidence interval 2.88, 7.10). There was also an increased risk with chicken eaten in restaurants (matched odds ratio 3.85; 2.52, 5.88). Recent consumption of baked or roasted chicken seemed to be protective. Campylobacteriosis was also associated with recent overseas travel, rainwater as a source of water at home, consumption of raw dairy products, and contact with puppies and cattle, particularly calves. Improperly cooked chicken seems to be associated with a large proportion of campylobacteriosis in New Zealand. Thorough cooking of chicken in homes and restaurants could reduce considerably the incidence of this disease.

The Misconception of Case-Control Studies in the Plastic Surgery Literature: A Literature Audit.

PubMed

Hatchell, Alexandra C; Farrokhyar, Forough; Choi, Matthew

2017-06-01

Case-control study designs are commonly used. However, many published case-control studies are not true case-controls and are in fact mislabeled. The purpose of this study was to identify all case-control studies published in the top three plastic surgery journals over the past 10 years, assess which were truly case-control studies, clarify the actual design of the articles, and address common misconceptions. MEDLINE, Embase, and Web of Science databases were searched for case-control studies in the three highest-impact factor plastic surgery journals (2005 to 2015). Two independent reviewers screened the resulting titles, abstracts, and methods, if applicable, to identify articles labeled as case-control studies. These articles were appraised and classified as true case-control studies or non-case-control studies. The authors found 28 articles labeled as case-control studies. However, only six of these articles (21 percent) were truly case-control designs. Of the 22 incorrectly labeled studies, one (5 percent) was a randomized controlled trial, three (14 percent) were nonrandomized trials, two (9 percent) were prospective comparative cohort designs, 14 (64 percent) were retrospective comparative cohort designs, and two (9 percent) were cross-sectional designs. The mislabeling was worse in recent years, despite increases in evidence-based medicine awareness. The majority of published case-control studies are not in fact case-control studies. This misunderstanding is worsening with time. Most of these studies are actually comparative cohort designs. However, some studies are truly clinical trials and thus a higher level of evidence than originally proposed.

Unprovoked seizures after traumatic brain injury: A population-based case-control study.

PubMed

Mahler, Benno; Carlsson, Sofia; Andersson, Tomas; Adelöw, Cecilia; Ahlbom, Anders; Tomson, Torbjörn

2015-09-01

To quantify the risk of unprovoked seizures after traumatic brain injury (TBI) METHODS: We used the Stockholm Incidence Registry on Epilepsy to carry out a population-based case-control study, including 1,885 cases with incident unprovoked seizures from September 1, 2000 through August 31, 2008, together with 15,080 matched controls. Information of prior hospitalizations for TBI was obtained through record linkage with the Swedish National Inpatient Registry for the period 1980-2008. Relative risks (RRs) for unprovoked seizures were estimated after various TBI diagnoses, and influences of TBI severity and time since trauma were studied in detail. After hospitalization for mild TBI, the RR was 2.0 (95% confidence interval [CI] 1.5-2.7). The RR was higher after brain contusion (5.9, 95% CI 2.4-15.0) or intracranial hemorrhage (ICH) (4.5, 95% CI 2.2-9.0), whereas a combination of both diagnoses led to a further sevenfold increase in RR (42.6, 95% CI 12.2-148.5). The risk was greatest during the first 6 months after severe TBI (RR 48.9, 95% CI 10.9-218.9) or mild TBI (RR 8.1, 95% CI 3.1-21.7), but was still elevated >10 years after any TBI. Herein we present a large population-based case-control study on TBI as a risk factor for unprovoked epileptic seizures, including cases of all ages with individually validated seizure diagnoses. The risk for epileptic seizures was substantially increased after TBI, especially during the first 6 months after the injury and in patients with a combination of ICH and brain contusion. Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Primary aldosteronism and thyroid disorders in atrial fibrillation: A Swedish nationwide case-control study.

PubMed

Mourtzinis, Georgios; Adamsson Eryd, Samuel; Rosengren, Annika; Björck, Lena; Adiels, Martin; Johannsson, Gudmundur; Manhem, Karin

2018-05-01

Background Atrial fibrillation is associated with hyperthyroidism. Patients with primary aldosteronism have an increased prevalence of atrial fibrillation. However, the prevalence of primary aldosteronism in the atrial fibrillation population is unknown. Aim This nationwide case-control study aimed to compare the prevalence of primary aldosteronism and thyroid disorders in patients with atrial fibrillation with that of age- and sex-matched controls. Methods We identified all atrial fibrillation cases in Sweden between 1987 and 2013 ( n = 713,569) by using the Swedish National Patient Register. A control cohort without atrial fibrillation was randomly selected from the Swedish Total Population Register with a case to control ratio of 1:2. This control cohort was matched for age, sex and place of birth ( n = 1,393,953). Results The prevalence of primary aldosteronism in December 2013 was 0.056% in the atrial fibrillation cohort and 0.024% in controls. At the same time, the prevalence of hypothyroidism was 5.9% in the atrial fibrillation cohort and 3.7% in controls. The prevalence of hyperthyroidism was 2.3% in the atrial fibrillation cohort and 0.8% in controls. Conclusion This study shows, for the first time, a doubled prevalence of primary aldosteronism in a large cohort of patients with atrial fibrillation compared with the general population. There is also an increased prevalence of hypo- and hyper-thyroidism in patients with atrial fibrillation compared with the general population.

A matched case-control study of convenience store robbery risk factors.

PubMed

Hendricks, S A; Landsittel, D P; Amandus, H E; Malcan, J; Bell, J

1999-11-01

Convenience store clerks have been shown to be at high risk for assault and homicide, mostly owing to robbery or robbery attempts. Although the literature consistently indicates that at least some environmental designs are effective deterrents of robbery, the significance of individual interventions and policies has differed across past studies. To address these issues, a matched case-control study of 400 convenience store robberies in three metropolitan areas of Virginia was conducted. Conditional logistic regression was implemented to evaluate the significance of various environmental designs and other factors possibly related to convenience store robbery. Findings indicate that numerous characteristics of the surrounding environment and population were significantly associated with convenience store robbery. Results also showed that, on a univariate level, most crime prevention factors were significantly associated with a lower risk for robbery. Using a forward selection process, a multivariate model, which included cash handling policy, bullet-resistant shielding, and numerous characteristics of the surrounding area and population, was identified. This study addressed numerous limitations of the previous literature by prospectively collecting extensive data on a large sample of diverse convenience stores and directly addressing the current theory on the robbers' selection of a target store through a matched case-control design.

Neurocognitive performance in family-based and case-control studies of schizophrenia

PubMed Central

Gur, Ruben C.; Braff, David L.; Calkins, Monica E.; Dobie, Dorcas J.; Freedman, Robert; Green, Michael F.; Greenwood, Tiffany A.; Lazzeroni, Laura C.; Light, Gregory A.; Nuechterlein, Keith H.; Olincy, Ann; Radant, Allen D.; Seidman, Larry J.; Siever, Larry J.; Silverman, Jeremy M.; Sprock, Joyce; Stone, William S.; Sugar, Catherine A.; Swerdlow, Neal R.; Tsuang, Debby W.; Tsuang, Ming T.; Turetsky, Bruce I.; Gur, Raquel E.

2014-01-01

Background Neurocognitive deficits in schizophrenia (SZ) are established and the Consortium on the Genetics of Schizophrenia (COGS) investigated such measures as endophenotypes in family-based (COGS-1) and case-control (COGS-2) studies. By requiring family participation, family-based sampling may result in samples that vary demographically and perform better on neurocognitive measures. Methods The Penn computerized neurocognitive battery (CNB) evaluates accuracy and speed of performance for several domains and was administered across sites in COGS-1 and COGS-2. Most tests were included in both studies. COGS-1 included 328 patients with SZ and 497 healthy comparison subjects (HCS) and COGS-2 included 1195 patients and 1009 HCS. Results Demographically, COGS-1 participants were younger, more educated, with more educated parents and higher estimated IQ compared to COGS-2 participants. After controlling for demographics, the two samples produced very similar performance profiles compared to their respective controls. As expected, performance was better and with smaller effect sizes compared to controls in COGS-1 relative to COGS-2. Better performance was most pronounced for spatial processing while emotion identification had large effect sizes for both accuracy and speed in both samples. Performance was positively correlated with functioning and negatively with negative and positive symptoms in both samples, but correlations were attenuated in COGS-2, especially with positive symptoms. Conclusions Patients ascertained through family-based design have more favorable demographics and better performance on some neurocognitive domains. Thus, studies that use case-control ascertainment may tap into populations with more severe forms of illness that are exposed to less favorable factors compared to those ascertained with family-based designs. PMID:25432636

Neurocognitive performance in family-based and case-control studies of schizophrenia.

PubMed

Gur, Ruben C; Braff, David L; Calkins, Monica E; Dobie, Dorcas J; Freedman, Robert; Green, Michael F; Greenwood, Tiffany A; Lazzeroni, Laura C; Light, Gregory A; Nuechterlein, Keith H; Olincy, Ann; Radant, Allen D; Seidman, Larry J; Siever, Larry J; Silverman, Jeremy M; Sprock, Joyce; Stone, William S; Sugar, Catherine A; Swerdlow, Neal R; Tsuang, Debby W; Tsuang, Ming T; Turetsky, Bruce I; Gur, Raquel E

2015-04-01

Neurocognitive deficits in schizophrenia (SZ) are established and the Consortium on the Genetics of Schizophrenia (COGS) investigated such measures as endophenotypes in family-based (COGS-1) and case-control (COGS-2) studies. By requiring family participation, family-based sampling may result in samples that vary demographically and perform better on neurocognitive measures. The Penn computerized neurocognitive battery (CNB) evaluates accuracy and speed of performance for several domains and was administered across sites in COGS-1 and COGS-2. Most tests were included in both studies. COGS-1 included 328 patients with SZ and 497 healthy comparison subjects (HCS) and COGS-2 included 1195 patients and 1009 HCS. Demographically, COGS-1 participants were younger, more educated, with more educated parents and higher estimated IQ compared to COGS-2 participants. After controlling for demographics, the two samples produced very similar performance profiles compared to their respective controls. As expected, performance was better and with smaller effect sizes compared to controls in COGS-1 relative to COGS-2. Better performance was most pronounced for spatial processing while emotion identification had large effect sizes for both accuracy and speed in both samples. Performance was positively correlated with functioning and negatively with negative and positive symptoms in both samples, but correlations were attenuated in COGS-2, especially with positive symptoms. Patients ascertained through family-based design have more favorable demographics and better performance on some neurocognitive domains. Thus, studies that use case-control ascertainment may tap into populations with more severe forms of illness that are exposed to less favorable factors compared to those ascertained with family-based designs.

A case-control study of the association between ulcerative colitis and hyperthyroidism in an Asian population.

PubMed

Tsai, Ming-Chieh; Lin, Herng-Ching; Lee, Cha-Ze

2017-06-01

Ulcerative colitis (UC) is a chronic relapsing inflammatory disease with significant clinical diversity. However, the aetiology, pathogenesis and optimal treatment of UC remain unclear. The purpose of this case-control study was to investigate the association between previously diagnosed hyperthyroidism and UC using a large population-based data set in Taiwan. The data for this population-based case-control study were retrieved from the Taiwan Longitudinal Health Insurance Database 2005. We included 2709 patients with UC as cases and 8127 sex- and age-matched patients without UC as controls. A conditional logistic regression analysis was conducted to compute the odds ratio (OR) and corresponding 95% confidence interval (CI) for the association between UC and prior hyperthyroidism. We found that, in total, 327 of the 10 836 sampled patients (3.02%) had previously been diagnosed with hyperthyroidism. There was a higher proportion of prior hyperthyroidism among cases than controls (4.10% vs 2.66%, P<.001). A conditional logistic regression showed that the OR of prior hyperthyroidism was 1.57 (95% CI=1.24-1.98) compared to controls. Similarly, after adjusting for monthly income, geographic location and urbanization level, cases were still more likely to have previously been diagnosed with hyperthyroidism than controls (OR=1.61, 95% CI=1.27-2.05). Furthermore, we analysed the ORs of prior hyperthyroidism between cases and controls according to age group. We found that of the youngest group of sampled patients (18-39 years), cases had the greatest adjusted OR for having previously been diagnosed with hyperthyroidism than controls (OR=1.98, 95% CI=1.04-3.79). This study demonstrated an association between UC and hyperthyroidism. © 2017 John Wiley & Sons Ltd.

Is case-chaos methodology an appropriate alternative to conventional case-control studies for investigating outbreaks?

PubMed

Edelstein, Michael; Wallensten, Anders; Kühlmann-Berenzon, Sharon

2014-08-15

Case-chaos methodology is a proposed alternative to case-control studies that simulates controls by randomly reshuffling the exposures of cases. We evaluated the method using data on outbreaks in Sweden. We identified 5 case-control studies from foodborne illness outbreaks that occurred between 2005 and 2012. Using case-chaos methodology, we calculated odds ratios 1,000 times for each exposure. We used the median as the point estimate and the 2.5th and 97.5th percentiles as the confidence interval. We compared case-chaos matched odds ratios with their respective case-control odds ratios in terms of statistical significance. Using Spearman's correlation, we estimated the correlation between matched odds ratios and the proportion of cases exposed to each exposure and quantified the relationship between the 2 using a normal linear mixed model. Each case-control study identified an outbreak vehicle (odds ratios = 4.9-45). Case-chaos methodology identified the outbreak vehicle 3 out of 5 times. It identified significant associations in 22 of 113 exposures that were not associated with outcome and 5 of 18 exposures that were significantly associated with outcome. Log matched odds ratios correlated with their respective proportion of cases exposed (Spearman ρ = 0.91) and increased significantly with the proportion of cases exposed (b = 0.054). Case-chaos methodology missed the outbreak source 2 of 5 times and identified spurious associations between a number of exposures and outcome. Measures of association correlated with the proportion of cases exposed. We recommended against using case-chaos analysis during outbreak investigations. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Residential traffic noise exposure and vestibular schwannoma - a Danish case-control study.

PubMed

Roswall, Nina; Stangerup, Sven-Eric; Cayé-Thomasen, Per; Schüz, Joachim; Johansen, Christoffer; Jensen, Steen Solvang; Raaschou-Nielsen, Ole; Sørensen, Mette

2017-10-01

Few risk factors for sporadic vestibular schwannoma (VS) are known. Several studies have proposed an increased risk with occupational noise exposure, whereas no studies have investigated residential traffic noise exposure as a risk factor. The present study investigated if residential traffic noise was associated with vestibular schwannoma in a large, population-based Danish case-control study. We identified 1454 VS cases, age above 30 years at diagnosis, between 1990 and 2007. For each case, we selected two random population controls, matched on sex and year of birth. Road and railway traffic noise at the residence was calculated for all present and historical addresses between 1987 and index date. Associations between traffic noise and risk for VS were estimated using conditional logistic regression, adjusted for education, disposable personal income, cohabitation status, railway noise exposure, municipal population density, and municipal income. A two-year time-weighted mean road traffic noise exposure was associated with an adjusted odds ratio of 0.92 (0.82-1.03) for developing VS, per 10 dB increment. There was no clear trend in categorical analyses. Similarly, linear and categorical analyses of residential railway noise did not suggest an association. We found no interaction with demographics, year of diagnosis, individual and municipal socioeconomic variables, and railway noise exposure. The results did not differ by tumor side, spread or size. The present study does not suggest an association between residential traffic noise and VS.

Correcting for batch effects in case-control microbiome studies

PubMed Central

Gibbons, Sean M.; Duvallet, Claire

2018-01-01

High-throughput data generation platforms, like mass-spectrometry, microarrays, and second-generation sequencing are susceptible to batch effects due to run-to-run variation in reagents, equipment, protocols, or personnel. Currently, batch correction methods are not commonly applied to microbiome sequencing datasets. In this paper, we compare different batch-correction methods applied to microbiome case-control studies. We introduce a model-free normalization procedure where features (i.e. bacterial taxa) in case samples are converted to percentiles of the equivalent features in control samples within a study prior to pooling data across studies. We look at how this percentile-normalization method compares to traditional meta-analysis methods for combining independent p-values and to limma and ComBat, widely used batch-correction models developed for RNA microarray data. Overall, we show that percentile-normalization is a simple, non-parametric approach for correcting batch effects and improving sensitivity in case-control meta-analyses. PMID:29684016

Multiple imputation of missing data in nested case-control and case-cohort studies.

PubMed

Keogh, Ruth H; Seaman, Shaun R; Bartlett, Jonathan W; Wood, Angela M

2018-06-05

The nested case-control and case-cohort designs are two main approaches for carrying out a substudy within a prospective cohort. This article adapts multiple imputation (MI) methods for handling missing covariates in full-cohort studies for nested case-control and case-cohort studies. We consider data missing by design and data missing by chance. MI analyses that make use of full-cohort data and MI analyses based on substudy data only are described, alongside an intermediate approach in which the imputation uses full-cohort data but the analysis uses only the substudy. We describe adaptations to two imputation methods: the approximate method (MI-approx) of White and Royston () and the "substantive model compatible" (MI-SMC) method of Bartlett et al. (). We also apply the "MI matched set" approach of Seaman and Keogh () to nested case-control studies, which does not require any full-cohort information. The methods are investigated using simulation studies and all perform well when their assumptions hold. Substantial gains in efficiency can be made by imputing data missing by design using the full-cohort approach or by imputing data missing by chance in analyses using the substudy only. The intermediate approach brings greater gains in efficiency relative to the substudy approach and is more robust to imputation model misspecification than the full-cohort approach. The methods are illustrated using the ARIC Study cohort. Supplementary Materials provide R and Stata code. © 2018, The International Biometric Society.

Statins and hip fracture risk in men: a population-based case-control study.

PubMed

Adams, Annette L; Shi, Jiaxiao M; Reynolds, Kristi; Haque, Reina; Cheetham, T Craig; Kawatkar, Aniket A; Fithian, Donald C; Jacobsen, Steven J

2015-11-01

To estimate the association between hydroxymethylglutaryl-CoA inhibitor (statin) use and hip fracture. We conducted a population-based case-control study. Cases were 6774 male enrollees in a large managed care organization, aged 45 or more years, with an incident hip fracture from 1997 to 2006. Controls without fracture (n = 6774) were matched to cases on age, race, and medical center. Electronic information on pharmaceutical use was used to identify the dispensing of statins from 1991 forward. Overall, 1884 (27.8%) cases and 2150 controls (31.7%) used a statin before index date (matched odds ratio [mOR] = 0.81, 95% confidence interval [CI] = 0.74-0.87). Adjustment for comorbidity burden strengthened the magnitude of the overall association (mOR = 0.68, CI = 0.62-0.74). The adjusted association was similar across age groups but was strongest among men aged 80 years or more (mOR = 0.62, CI = 0.54-0.71) and was most pronounced in African Americans (mOR = 0.43, CI = 0.28-0.64). Greater duration of statin use did not alter the odds ratios. These data add to the growing evidence of a potential protective effect of statin use on bone health. However, these results need to be replicated in a prospective study that can account for confounding by indication which may explain these findings. Copyright © 2015 Elsevier Inc. All rights reserved.

Should Controls With Respiratory Symptoms Be Excluded From Case-Control Studies of Pneumonia Etiology? Reflections From the PERCH Study

PubMed Central

Hammitt, Laura L.; Deloria Knoll, Maria; Baggett, Henry C.; Brooks, W. Abdullah; Howie, Stephen R. C.; Kotloff, Karen L.; Levine, Orin S.; Madhi, Shabir A.; Murdoch, David R.; Scott, J. Anthony G.; Thea, Donald M.; Driscoll, Amanda J.; Karron, Ruth A.; Park, Daniel E.; Prosperi, Christine; Zeger, Scott L.; O’Brien, Katherine L.; Feikin, Daniel R.; O’Brien, Katherine L.; Levine, Orin S.; Knoll, Maria Deloria; Feikin, Daniel R.; DeLuca, Andrea N.; Driscoll, Amanda J.; Fu, Wei; Hammitt, Laura L.; Higdon, Melissa M.; Kagucia, E. Wangeci; Karron, Ruth A.; Li, Mengying; Park, Daniel E.; Prosperi, Christine; Wu, Zhenke; Zeger, Scott L.; Watson, Nora L.; Crawley, Jane; Murdoch, David R.; Brooks, W. Abdullah; Endtz, Hubert P.; Zaman, Khalequ; Goswami, Doli; Hossain, Lokman; Jahan, Yasmin; Ashraf, Hasan; Howie, Stephen R. C.; Ebruke, Bernard E.; Antonio, Martin; McLellan, Jessica; Machuka, Eunice; Shamsul, Arifin; Zaman, Syed M.A.; Mackenzie, Grant; Scott, J. Anthony G.; Awori, Juliet O.; Morpeth, Susan C.; Kamau, Alice; Kazungu, Sidi; Kotloff, Karen L.; Tapia, Milagritos D.; Sow, Samba O.; Sylla, Mamadou; Tamboura, Boubou; Onwuchekwa, Uma; Kourouma, Nana; Toure, Aliou; Madhi, Shabir A.; Moore, David P.; Adrian, Peter V.; Baillie, Vicky L.; Kuwanda, Locadiah; Mudau, Azwifarwi; Groome, Michelle J.; Baggett, Henry C.; Thamthitiwat, Somsak; Maloney, Susan A.; Bunthi, Charatdao; Rhodes, Julia; Sawatwong, Pongpun; Akarasewi, Pasakorn; Thea, Donald M.; Mwananyanda, Lawrence; Chipeta, James; Seidenberg, Phil; Mwansa, James; wa Somwe, Somwe; Kwenda, Geoffrey

2017-01-01

Abstract Many pneumonia etiology case-control studies exclude controls with respiratory illness from enrollment or analyses. Herein we argue that selecting controls regardless of respiratory symptoms provides the least biased estimates of pneumonia etiology. We review 3 reasons investigators may choose to exclude controls with respiratory symptoms in light of epidemiologic principles of control selection and present data from the Pneumonia Etiology Research for Child Health (PERCH) study where relevant to assess their validity. We conclude that exclusion of controls with respiratory symptoms will result in biased estimates of etiology. Randomly selected community controls, with or without respiratory symptoms, as long as they do not meet the criteria for case-defining pneumonia, are most representative of the general population from which cases arose and the least subject to selection bias. PMID:28575354

Occupation and lung cancer in Shanghai: a case-control study.

PubMed Central

Levin, L I; Zheng, W; Blot, W J; Gao, Y T; Fraumeni, J F

1988-01-01

Occupation was evaluated as a potential risk factor for lung cancer as part of a large population based case-control study conducted in the ten urban districts of Shanghai. A total of 733 newly diagnosed cases of male lung cancer and 760 controls selected from the general population was interviewed to obtain lifetime occupational histories and information on smoking and other factors. Of the approximately 25 major industrial titles examined, significantly raised risks, adjusted for smoking, were found for employment in agricultural production (odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.0-2.6). A concomitant increase was detected for farmers (OR = 1.6, 95% CI = 1.0-2.5) when 35 major occupational titles were examined. There was a 70% excess among workers in the chemical industry (OR = 1.7, 95% CI = 0.9-3.1) and a significant decrease among textile industry workers (OR = 0.7, 95% CI = 0.5-1.0). Raised risks of 30% to 80% were associated with reported job exposures to wood and coal dusts, smoke from burning fuels, and chemical fumes. Employment categories were also examined for 672 cases and 735 controls among women, but small numbers in many of the industrial and occupational categories precluded detailed analyses. The largest excess risk among women (OR = 5.1, 95% CI 1.3-23.5) was among glass products workers. Although cigarette smoking was the dominant cause of lung cancer among men and a significant risk factor among women in Shanghai, these findings suggest the importance of certain workplace exposures and offer leads to occupational carcinogens. PMID:3395581

Body Weight and Breast Cancer: Nested Case-Control Study in Southern Brazil.

PubMed

Kops, Natália Luiza; Bessel, Marina; Caleffi, Maira; Ribeiro, Rodrigo Antonini; Wendland, Eliana Marcia

2018-04-28

Current studies have shown that fast weight gain may be more important than body mass index on the incidence of breast cancer. The aim of this study was to evaluate the association between body weight and breast cancer. This was a case-control study nested in a cohort of a breast cancer mammography screening program in Southern Brazil. A trained investigator administered a standardized interview to collect sociodemographic and clinical data, and body weight history (weight at menarche, at marriage, at first and last pregnancy, and at menopause). Current anthropometric measurements were also made. Fifty-seven women with cancer (66.7% postmenopausal) and 159 controls were included. Current age (60.3 ± 10.4 vs. 55.8 ± 8.4 years, P < .01), marital status (49.1% vs. 64.8% with a partner, P = .03), and physical activity (48.2% vs. 32.3% sedentary, P = .01) were significantly different between cases and controls, respectively. Odds ratio showed that age and current waist circumference were associated with postmenopausal cancer. No difference was found in relation to body weight at different stages of life. Women with social vulnerability recruited at a mammography screening program in Southern Brazil showed a large weight gain during life, but no significant differences were found in body weight between women with or without breast cancer. Copyright © 2018 Elsevier Inc. All rights reserved.

The study on servo-control system in the large aperture telescope

NASA Astrophysics Data System (ADS)

Hu, Wei; Zhenchao, Zhang; Daxing, Wang

2008-08-01

Large astronomical telescope or extremely enormous astronomical telescope servo tracking technique will be one of crucial technology that must be solved in researching and manufacturing. To control technique feature of large astronomical telescope or extremely enormous astronomical telescope, this paper design a sort of large astronomical telescope servo tracking control system. This system composes a principal and subordinate distributed control system, host computer sends steering instruction and receive slave computer functional mode, slave computer accomplish control algorithm and execute real-time control. Large astronomical telescope servo control use direct drive machine, and adopt DSP technology to complete direct torque control algorithm, Such design can not only increase control system performance, but also greatly reduced volume and costs of control system, which has a significant occurrence. The system design scheme can be proved reasonably by calculating and simulating. This system can be applied to large astronomical telescope.

Injury case-control studies using "other injuries" as controls.

PubMed

Marshall, Stephen W

2008-03-01

Studies of event-related (or "event-phase") interventions (such as ski helmets) can address injury at a specific body site (such as the head) by using as controls a group of people who experienced the same event (fall) and suffered injuries at other body sites (other than the head). The research question addressed by this type of study is the effect of an exposure or intervention (helmet) during the event phase (fall) of the causal chain. However, this is a valid case-control design only if the controls (skiers with other injuries) provide a reasonable proxy for the prevalence of exposure (helmet-wearing) in the underlying event-phase source population (skiers who fell). This assumption needs to be carefully assessed. Factors associated with both helmet-wearing and injury given a fall (eg, previous injury history, skiing inexperience, or risk-taking behavior) have considerable potential to create bias.

Brucellosis in Ontario: a case control study.

PubMed Central

Kellar, J; Marra, R; Martin, W

1976-01-01

Data from cattle herds infected with brucellosis and from control (noninfected) herds were collected and analyzed using case control techniques. It appeared that herds located close to other infected herds and those herds whose owners made frequent purchases of cattle had an increased risk of acquiring brucellosis, particularly those who made purchases from other herds or from cattle dealers. Infected herds had a lower level of vaccination than noninfected herds. However, the percentage vaccinated was highly variable in each group. Vaccination per se did not appear to adversely influence the interpretation of serological test results nor did it appear to protect the individual animal. Once infected, the time required to become free of brucellosis was increased by large herd size and/or loose housing. Closed herds also took longer to become brucellosis free than more open herds. The percentage of animals removed from the herd was increased by active abortion. Those herds with multiple serological reactors (positives and questionables) at the first herd test after the imposition of quarantine had the highest percentage of cattle removed. PMID:826309

Toxocariasis and childhood asthma: A case-control study.

PubMed

Cadore, Priscila Silva; Zhang, Linjie; Lemos, Liliam de Lima; Lorenzi, Carolina; Telmo, Paula de Lima; Dos Santos, Paula Costa; Mattos, Gabriela Torres; Vignol, Flávia Saraçol; Prietsch, Silvio O M; Berne, Maria Elisabeth Aires; Scaini, Carlos James

2016-08-01

The objective of this study is to investigate the association between anti-Toxocara IgG seropositivity and asthma in children. This was a case-control study conducted in a university hospital in south Brazil between May 2012 and June 2013. Were recruited 208 children up to 12 years old of whom 156 had asthma (cases) and 52 did not have asthma (controls), with a case-control ratio of 3:1 matched by age. Children's parents or guardians were interviewed using a structured questionnaire with closed questions. Serology was performed using enzyme-linked immunosorbent assay (ELISA) with excretory-secretory antigen of Toxocara canis (TES). The seroprevalence of IgG anti-T. canis antibodies was 12.8% in the cases and 7.7% in the controls. There was no significant association between seropositivity to T. canis and risk of asthma (adjusted odds ratio [OR]: 1.89, 95% CI: 0.52 to 6.89, p = 0.33). Household income < 2 minimum salaries, paternal school years < 9, allergic rhinitis in children, a positive family history of asthma and rhinitis and contact with cats were significantly associated with asthma, with adjusted ORs (95% CIs) of 3.05 (1.21 to 7.73), 2.83 (1.11 to 7.18), 10.5 (4.32 to 25.6), 2.65 (1.14 to 6.17), 2.49 (1.07 to 5.78) and 2.73 (1.03 to 7.27), respectively. This study did not find a statistically significant association between seropositivity to Toxocara sp. and risk of asthma in children. Low family income, low paternal education level, concomitant allergic rhinitis, family history of asthma and allergic rhinitis and contact with cats were independent factors associated with childhood asthma.

Environment And Genetics in Lung cancer Etiology (EAGLE) study: an integrative population-based case-control study of lung cancer.

PubMed

Landi, Maria Teresa; Consonni, Dario; Rotunno, Melissa; Bergen, Andrew W; Goldstein, Alisa M; Lubin, Jay H; Goldin, Lynn; Alavanja, Michael; Morgan, Glen; Subar, Amy F; Linnoila, Ilona; Previdi, Fabrizio; Corno, Massimo; Rubagotti, Maurizia; Marinelli, Barbara; Albetti, Benedetta; Colombi, Antonio; Tucker, Margaret; Wacholder, Sholom; Pesatori, Angela C; Caporaso, Neil E; Bertazzi, Pier Alberto

2008-06-06

Lung cancer is the leading cause of cancer mortality worldwide. Tobacco smoking is its primary cause, and yet the precise molecular alterations induced by smoking in lung tissue that lead to lung cancer and impact survival have remained obscure. A new framework of research is needed to address the challenges offered by this complex disease. We designed a large population-based case-control study that combines a traditional molecular epidemiology design with a more integrative approach to investigate the dynamic process that begins with smoking initiation, proceeds through dependency/smoking persistence, continues with lung cancer development and ends with progression to disseminated disease or response to therapy and survival. The study allows the integration of data from multiple sources in the same subjects (risk factors, germline variation, genomic alterations in tumors, and clinical endpoints) to tackle the disease etiology from different angles. Before beginning the study, we conducted a phone survey and pilot investigations to identify the best approach to ensure an acceptable participation in the study from cases and controls. Between 2002 and 2005, we enrolled 2101 incident primary lung cancer cases and 2120 population controls, with 86.6% and 72.4% participation rate, respectively, from a catchment area including 216 municipalities in the Lombardy region of Italy. Lung cancer cases were enrolled in 13 hospitals and population controls were randomly sampled from the area to match the cases by age, gender and residence. Detailed epidemiological information and biospecimens were collected from each participant, and clinical data and tissue specimens from the cases. Collection of follow-up data on treatment and survival is ongoing. EAGLE is a new population-based case-control study that explores the full spectrum of lung cancer etiology, from smoking addiction to lung cancer outcome, through examination of epidemiological, molecular, and clinical data. We have

Ticagrelor and bradycardia: a nested case-control study.

PubMed

Turgeon, Ricky D; Fernandes, Kimberly A; Juurlink, David; Tu, Jack V; Mamdani, Muhammad

2015-12-01

Ticagrelor increases serum adenosine concentrations, slowing conduction and possibly leading to bradycardia. Clinical trial data have shown numerically, though not statistically significantly, higher rates of bradyarrhythmias with ticagrelor versus clopidogrel. Additionally, recent case reports have further raised concerns for this adverse effect. We explored the association between ticagrelor and hospitalization for bradycardia in a real-world setting. We conducted a population-based, nested case-control study of Ontario residents, 66 years of age or older, discharged after a first acute coronary syndrome by linking multiple healthcare databases. Cases included patients hospitalized for bradycardia within 1 year of starting a P2Y12 inhibitor. For each case, we identified 4 controls matched on age, sex, index date, and current use of a P2Y12 inhibitor. The exposure of interest was a prescription for ticagrelor within 90 days, with clopidogrel use as the reference group. From April 2012 to March 2014, we identified 140 cases and 560 controls who met the study criteria. We found no significant association between bradycardia and exposure to ticagrelor relative to clopidogrel in the previous 90 days prior to the index date (adjusted odds ratio 1.06, 95% confidence interval 0.65-2.21). Further adjustment for potential confounders also did not identify a significant association. Among older patients with a first acute coronary syndrome, use of ticagrelor was not associated with a greater risk of admission for bradycardia relative to clopidogrel. Copyright © 2015 John Wiley & Sons, Ltd.

Reducing selection bias in case-control studies from rare disease registries.

PubMed

Cole, J Alexander; Taylor, John S; Hangartner, Thomas N; Weinreb, Neal J; Mistry, Pramod K; Khan, Aneal

2011-09-12

In clinical research of rare diseases, where small patient numbers and disease heterogeneity limit study design options, registries are a valuable resource for demographic and outcome information. However, in contrast to prospective, randomized clinical trials, the observational design of registries is prone to introduce selection bias and negatively impact the validity of data analyses. The objective of the study was to demonstrate the utility of case-control matching and the risk-set method in order to control bias in data from a rare disease registry. Data from the International Collaborative Gaucher Group (ICGG) Gaucher Registry were used as an example. A case-control matching analysis using the risk-set method was conducted to identify two groups of patients with type 1 Gaucher disease in the ICGG Gaucher Registry: patients with avascular osteonecrosis (AVN) and those without AVN. The frequency distributions of gender, decade of birth, treatment status, and splenectomy status were presented for cases and controls before and after matching. Odds ratios (and 95% confidence intervals) were calculated for each variable before and after matching. The application of case-control matching methodology results in cohorts of cases (i.e., patients with AVN) and controls (i.e., patients without AVN) who have comparable distributions for four common parameters used in subject selection: gender, year of birth (age), treatment status, and splenectomy status. Matching resulted in odds ratios of approximately 1.00, indicating no bias. We demonstrated bias in case-control selection in subjects from a prototype rare disease registry and used case-control matching to minimize this bias. Therefore, this approach appears useful to study cohorts of heterogeneous patients in rare disease registries.

A prevalence-based association test for case-control studies.

PubMed

Ryckman, Kelli K; Jiang, Lan; Li, Chun; Bartlett, Jacquelaine; Haines, Jonathan L; Williams, Scott M

2008-11-01

Genetic association is often determined in case-control studies by the differential distribution of alleles or genotypes. Recent work has demonstrated that association can also be assessed by deviations from the expected distributions of alleles or genotypes. Specifically, multiple methods motivated by the principles of Hardy-Weinberg equilibrium (HWE) have been developed. However, these methods do not take into account many of the assumptions of HWE. Therefore, we have developed a prevalence-based association test (PRAT) as an alternative method for detecting association in case-control studies. This method, also motivated by the principles of HWE, uses an estimated population allele frequency to generate expected genotype frequencies instead of using the case and control frequencies separately. Our method often has greater power, under a wide variety of genetic models, to detect association than genotypic, allelic or Cochran-Armitage trend association tests. Therefore, we propose PRAT as a powerful alternative method of testing for association.

Development and validation of a melanoma risk score based on pooled data from 16 case-control studies

PubMed Central

Davies, John R; Chang, Yu-mei; Bishop, D Timothy; Armstrong, Bruce K; Bataille, Veronique; Bergman, Wilma; Berwick, Marianne; Bracci, Paige M; Elwood, J Mark; Ernstoff, Marc S; Green, Adele; Gruis, Nelleke A; Holly, Elizabeth A; Ingvar, Christian; Kanetsky, Peter A; Karagas, Margaret R; Lee, Tim K; Le Marchand, Loïc; Mackie, Rona M; Olsson, Håkan; Østerlind, Anne; Rebbeck, Timothy R; Reich, Kristian; Sasieni, Peter; Siskind, Victor; Swerdlow, Anthony J; Titus, Linda; Zens, Michael S; Ziegler, Andreas; Gallagher, Richard P.; Barrett, Jennifer H; Newton-Bishop, Julia

2015-01-01

Background We report the development of a cutaneous melanoma risk algorithm based upon 7 factors; hair colour, skin type, family history, freckling, nevus count, number of large nevi and history of sunburn, intended to form the basis of a self-assessment webtool for the general public. Methods Predicted odds of melanoma were estimated by analysing a pooled dataset from 16 case-control studies using logistic random coefficients models. Risk categories were defined based on the distribution of the predicted odds in the controls from these studies. Imputation was used to estimate missing data in the pooled datasets. The 30th, 60th and 90th centiles were used to distribute individuals into four risk groups for their age, sex and geographic location. Cross-validation was used to test the robustness of the thresholds for each group by leaving out each study one by one. Performance of the model was assessed in an independent UK case-control study dataset. Results Cross-validation confirmed the robustness of the threshold estimates. Cases and controls were well discriminated in the independent dataset (area under the curve 0.75, 95% CI 0.73-0.78). 29% of cases were in the highest risk group compared with 7% of controls, and 43% of controls were in the lowest risk group compared with 13% of cases. Conclusion We have identified a composite score representing an estimate of relative risk and successfully validated this score in an independent dataset. Impact This score may be a useful tool to inform members of the public about their melanoma risk. PMID:25713022

High risk of brain tumors in military personnel: a case control study.

PubMed

Fallahi, P; Elia, G; Foddis, R; Cristaudo, A; Antonelli, A

2017-01-01

Scientific literature suggests a relationship between military occupation and the development of brain tumors, but no italian study has investigated on the impact of this job on the brain cancer morbidity. In this a study information were obtained from patients recruited in the Neurosurgical Department of the University-Hospital of Pisa, Italy, from 1990 to 1999. The study has been conducted as a case-control study. 161, newly diagnosed cases of brain tumors (glioma and meningiomas, histologically confirmed), were recruited, such as 483 controls (with other non tumoral neurologic diseases: trauma, hemorrhagic brain disorders, aneurism, etc), by matching cases and controls (1:3), for age (± 5 years) and gender. Cases and controls were interviewed in the Neurosurgical Department, University-Hospital of Pisa, Italy, and the occupational histories of cases and controls were compared. Cases and controls have showed a statistically significant difference, based on their occupation (military vs. non-military occupation). A statistically significant association was seen between brain tumors and military occupation among evaluated patients (p=0.013). Further studies regarding this population group are needed, to determine the causes for the increased risk of this cancer. Furthermore, a subsequent reevaluation in other patients collected in more recent years will be needed to evaluate the trend of this association.

Should Controls With Respiratory Symptoms Be Excluded From Case-Control Studies of Pneumonia Etiology? Reflections From the PERCH Study.

PubMed

Higdon, Melissa M; Hammitt, Laura L; Deloria Knoll, Maria; Baggett, Henry C; Brooks, W Abdullah; Howie, Stephen R C; Kotloff, Karen L; Levine, Orin S; Madhi, Shabir A; Murdoch, David R; Scott, J Anthony G; Thea, Donald M; Driscoll, Amanda J; Karron, Ruth A; Park, Daniel E; Prosperi, Christine; Zeger, Scott L; O'Brien, Katherine L; Feikin, Daniel R

2017-06-15

Many pneumonia etiology case-control studies exclude controls with respiratory illness from enrollment or analyses. Herein we argue that selecting controls regardless of respiratory symptoms provides the least biased estimates of pneumonia etiology. We review 3 reasons investigators may choose to exclude controls with respiratory symptoms in light of epidemiologic principles of control selection and present data from the Pneumonia Etiology Research for Child Health (PERCH) study where relevant to assess their validity. We conclude that exclusion of controls with respiratory symptoms will result in biased estimates of etiology. Randomly selected community controls, with or without respiratory symptoms, as long as they do not meet the criteria for case-defining pneumonia, are most representative of the general population from which cases arose and the least subject to selection bias. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Anal signs of child sexual abuse: a case-control study.

PubMed

Hobbs, Christopher J; Wright, Charlotte M

2014-05-27

There is uncertainty about the nature and specificity of physical signs following anal child sexual abuse. The study investigates the extent to which physical findings discriminate between children with and without a history of anal abuse. Retrospective case note review in a paediatric forensic unit. all eligible cases from 1990 to 2007 alleging anal abuse. all children examined anally from 1998 to 2007 with possible physical abuse or neglect with no identified concern regarding sexual abuse. Fisher's exact test (two-tailed) was performed to ascertain the significance of differences for individual signs between cases and controls. To explore the potential role of confounding, logistic regression was used to produce odds ratios adjusted for age and gender. A total of 184 cases (105 boys, 79 girls), average age 98.5 months (range 26 to 179) were compared with 179 controls (94 boys, 85 girls) average age 83.7 months (range 35-193). Of the cases 136 (74%) had one or more signs described in anal abuse, compared to 29 (16%) controls. 79 (43%) cases and 2 (1.1%) controls had >1 sign. Reflex anal dilatation (RAD) and venous congestion were seen in 22% and 36% of cases but <1% of controls (likelihood ratios (LR) 40, 60 respectively), anal fissure in 14% cases and 1.1% controls (LR 13), anal laxity in 27% cases and 3% controls (LR 10).Novel signs seen significantly more commonly in cases were anal fold changes, swelling and twitching. Erythema, swelling and fold changes were seen most commonly within 7 days of last reported contact; RAD, laxity, venous congestion, fissure and twitching were observed up to 6 months after the alleged assault. Anal findings are more common in children alleging anal abuse than in those presenting with physical abuse or neglect with no concern about sexual abuse. Multiple signs are rare in controls and support disclosed anal abuse.

Designed for Learning: A Case Study in Rethinking Teaching and Learning for a Large First Year Class

ERIC Educational Resources Information Center

Goldacre, Lisa; Bolt, Susan; Lambiris, Michael

2013-01-01

This paper presents a case study in which the principles of scholarship were applied to designing an approach to learning suitable for large classes. While this case study describes an Australian first year Business Law unit, the findings presented in this paper would be relevant to a wide range of teachers faced with large enrollments in first…

Evaluating psychiatric case-control studies using the STROBE (STrengthening the Reporting of OBservational Studies in Epidemiology) statement.

PubMed

Goi, Pedro Domingues; Goi, Julia Domingues; Cordini, Kariny Larissa; Ceresér, Keila Mendes; Rocha, Neusa Sica da

2014-01-01

Case-control studies are important in developing clinical and public health knowledge. The STROBE statement (STrengthening the Reporting of OBservational Studies in Epidemiology) was developed to establish a checklist of items that should be included in articles reporting observational studies. Our aim was to analyze whether the psychiatric case-control articles published in Brazilian journals with CAPES Qualis rating B1/B2 in 2009 conformed with the STROBE statement. Descriptive study on psychiatric papers published in Brazilian journals, within the Postgraduate Medical Program on Psychiatry, at Universidade Federal do Rio Grande do Sul. All psychiatric case-control studies from Brazilian Qualis B1/B2 journals of psychiatry, neurology and public health in 2009 were analyzed. The four most specific items of the STROBE statement were used to evaluate whether these studies fitted within the case-control parameters: 1) selection of cases and controls; 2) controlling for bias; 3) statistical analysis; and 4) presentation of results. Sixteen case-control studies were identified, of which eleven (68.75%) were in psychiatry-focused journals. From analysis using the STROBE statement, all of the articles conformed with item 1; two (12.5%) completely conformed with item 2; none completely conformed with item 3; and only three (18.8%) conformed with item 4. The case-control studies analyzed here did not completely conform with the four STROBE statement items for case-control design. In view of the inadequate methodology of the published studies, these findings justify focusing on research and methodology and expanding the investigations on adherence of studies to their designs.

Hypothyroidism among SLE patients: Case-control study.

PubMed

Watad, Abdulla; Mahroum, Naim; Whitby, Aaron; Gertel, Smadar; Comaneshter, Doron; Cohen, Arnon D; Amital, Howard

2016-05-01

The prevalence of hypothyroidism in SLE patients varies considerably and early reports were mainly based on small cohorts. To investigate the association between SLE and hypothyroidism. Patients with SLE were compared with age and sex-matched controls regarding the proportion of hypothyroidism in a case-control study. Chi-square and t-tests were used for univariate analysis and a logistic regression model was used for multivariate analysis. The study was performed utilizing the medical database of Clalit Health Services. The study included 5018 patients with SLE and 25,090 age and sex-matched controls. The proportion of hypothyroidism in patients with SLE was increased compared with the prevalence in controls (15.58% and 5.75%, respectively, P<0.001). In a multivariate analysis, SLE was associated with hypothyroidism (odds ratio 2.644, 95% confidence interval 2.405-2.908). Patients with SLE have a greater proportion of hypothyroidism than matched controls. Therefore, physicians treating patients with SLE should be aware of the possibility of thyroid dysfunction. Copyright © 2016 Elsevier B.V. All rights reserved.

Attributes of long-term heavy cannabis users: a case-control study.

PubMed

Gruber, A J; Pope, H G; Hudson, J I; Yurgelun-Todd, D

2003-11-01

Although cannabis is the most widely used illicit drug in the United States, few recent American studies have examined the attributes of long-term heavy cannabis users. Using a case-control design, we obtained psychological and demographic measures on 108 individuals, age 30-55, who had smoked cannabis a mean of 18000 times and a minimum of 5000 times in their lives. We compared these heavy users to 72 age-matched control subjects who had smoked at least once, but no more than 50 times in their lives. We found no significant differences between the two groups on reported levels of income and education in their families of origin. However, the heavy users themselves reported significantly lower educational attainment (P < 0.001) and income (P = 0.003) than the controls, even after adjustment for a large number of potentially confounding variables. When asked to rate the subjective effects of cannabis on their cognition, memory, career, social life, physical health and mental health, large majorities of heavy users (66-90%) reported a 'negative effect'. On several measures of quality of life, heavy users also reported significantly lower levels of satisfaction than controls. Both objective and self-report measures suggest numerous negative features associated with long-term heavy cannabis use. Thus, it seems important to understand why heavy users continue to smoke regularly for years, despite acknowledging these negative effects. Such an understanding may guide the development of strategies to treat cannabis dependence.

Case-control study of dementia of the Alzheimer type

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

French, L.R.; Schuman, L.M.; Mortimer, J.A.

1985-03-01

A case-control study to assess factors of possible etiologic significance to dementia of the Alzheimer type was conducted with 78 male cases diagnosed in 1979-1982 at the Veterans Administration Medical Center in Minneapolis, Minnesota and age-race-sex-matched hospital and neighborhood controls (14 of 16 autopsied cases were histopathologically confirmed). Information was obtained on variables relevant to vital, genetic, and immunologic hypotheses, and on possible occupational and environmental exposures, drug use, psychologic stress, smoking, and alcohol consumption. The only major difference between patients with dementia of the Alzheimer type and controls was a significantly greater occurrence of antecedent head trauma in themore » patients (odds ratio = 4.50). This finding is consistent with the literature on posttraumatic dementia but its importance is presently unclear.« less

CONTROL FUNCTION ASSISTED IPW ESTIMATION WITH A SECONDARY OUTCOME IN CASE-CONTROL STUDIES.

PubMed

Sofer, Tamar; Cornelis, Marilyn C; Kraft, Peter; Tchetgen Tchetgen, Eric J

2017-04-01

Case-control studies are designed towards studying associations between risk factors and a single, primary outcome. Information about additional, secondary outcomes is also collected, but association studies targeting such secondary outcomes should account for the case-control sampling scheme, or otherwise results may be biased. Often, one uses inverse probability weighted (IPW) estimators to estimate population effects in such studies. IPW estimators are robust, as they only require correct specification of the mean regression model of the secondary outcome on covariates, and knowledge of the disease prevalence. However, IPW estimators are inefficient relative to estimators that make additional assumptions about the data generating mechanism. We propose a class of estimators for the effect of risk factors on a secondary outcome in case-control studies that combine IPW with an additional modeling assumption: specification of the disease outcome probability model. We incorporate this model via a mean zero control function. We derive the class of all regular and asymptotically linear estimators corresponding to our modeling assumption, when the secondary outcome mean is modeled using either the identity or the log link. We find the efficient estimator in our class of estimators and show that it reduces to standard IPW when the model for the primary disease outcome is unrestricted, and is more efficient than standard IPW when the model is either parametric or semiparametric.

Pretreatment Circulating Serum Cytokines Associated with Follicular and Diffuse Large B-Cell Lymphoma: A Clinic-Based Case-Control Study

PubMed Central

Charbonneau, Bridget; Maurer, Matthew J; Ansell, Stephen M; Slager, Susan L; Fredericksen, Zachary S; Ziesmer, Steven C; Macon, William R; Habermann, Thomas M; Witzig, Thomas E; Link, Brian K; Cerhan, James R; Novak, Anne J

2012-01-01

Background Abnormal immune function is a key factor in predisposition to non-Hodgkin lymphoma (NHL). We evaluated the association of 30 cytokines individually and as a profile with diffuse large B-cell (DLBCL) and follicular (FL) lymphomas. Methods We used a multiplexed assay to measure 30 cytokine concentrations in pre-treatment serum in a case-control study of 234 FL, 188 DLBCL, and 400 control participants. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) adjusted for age and sex, and polytomous regression was used to evaluate heterogeneity between FL and DLBCL. Principal components analysis (PCA) was used to assess cytokine profiles associated with FL and DLBCL. Results In single cytokine modeling, we found that 12 of the 30 circulating serum cytokines were significantly (P<0.05) associated with FL and/or DLBCL after accounting for multiple testing (q<0.05). Soluble IL-2R (sIL-2R) had the strongest association with both FL (OR=6.0 for highest versus lowest tertile, 95% CI 3.8–9.5; p-trend=1.8 × 10−21) and DLBCL (OR=7.6, 95% CI 4.5–13.1; p-trend=7.2 × 10−20). IL1RA and IL-12p40 also showed similar associations for DLBCL and FL. In contrast, HGF, MIG, and MIP-1α had a stronger association with DLBCL compared to FL, and IL-6, IL-8, IL-10, IFN-γ, IP-10, and VEGF were only statistically significantly associated with DLBCL after accounting for multiple testing. However, in PCA modeling, a cytokine profile based on sIL-2R, IL-1RA, MIG, IP-10, IL-8, and IL-12p40 explained most of the variability between controls and both FL and DLBCL. Conclusions We identified some single cytokines unique to DLBCL, but overall cytokine associations were more similar than distinct for DLBCL and FL. While these data are limited by concerns of reverse causality, they do suggest cytokines and cytokine profiles that can be prioritized in future studies. PMID:23010502

[Case-control study on influence factors of birth defects].

PubMed

Xiu, Xin-hong; Yuan, Li; Wang, Xiao-ming; Chen, Yu-hua; Wan, Ai-hua; Fu, Ping

2011-07-01

To investigate the influence factors of birth defects. The congenital malformational fetuses born from 13 week of gestation to 7 days after birth were selected as the study group between April 1st, 2009 and March 31st, 2010. The health born fetuses were set as control in the same period. Case-control and the three-level of monitor network of birth defects were used in the study in the participating 75 hospitals (Qingdao Women and Children's Medical Center, Affiliated Hospital of Medical College Qingdao University, Qingdao Municipal Hospital, etc.). The study and control group's parents were interviewed by an uniformed questionnaire which was designed specially with influence factors of birth defects. (1) There are 466 congenital malformational fetuses in the total of 77 231 fetuses collected in 75 hospitals. The congenital malformational rate accounts for about 6.034‰. The top six defect diseases were congenital heart disease (112 cases), total harelip (cleft lip; cleft lip with palate: 85 cases), polydactyly (53 cases), neural tube defects (38 cases), congenital hydrocephalus (37 cases) and limb reduction defect (27 cases) in turn, which amounts to 353 cases (54.48%, 353/648). (2) Their mother education level in the birth-defect group (25.6%) were significantly lower than that in control group (30.0%, P<0.05). (3) The rate of passive smoking, drinking, raising pets of the parents in birth-defect group were significantly higher than that in control group (P<0.05). (4) The rate of exposure to harmful chemical and physical factors of mothers in birth defects group (13.9% and 20.5%, respectively) was higher than that in control group (1.1% and 11.7%, respectively), the difference between which were significant (P<0.01). The rate of disease (34.3%), fever (13.1%), taking drugs (33.8%) in pregnancy period in birth defect group were higher than that in control group (13.5%, 1.5% and 9.9%, respectively), the difference between which were significant (P<0.01). The rate

Suspected survivor bias in case-control studies: stratify on survival time and use a negative control.

PubMed

van Rein, Nienke; Cannegieter, Suzanne C; Rosendaal, Frits R; Reitsma, Pieter H; Lijfering, Willem M

2014-02-01

Selection bias in case-control studies occurs when control selection is inappropriate. However, selection bias due to improper case sampling is less well recognized. We describe how to recognize survivor bias (i.e., selection on exposed cases) and illustrate this with an example study. A case-control study was used to analyze the effect of statins on major bleedings during treatment with vitamin K antagonists. A total of 110 patients who experienced such bleedings were included 18-1,018 days after the bleeding complication and matched to 220 controls. A protective association of major bleeding for exposure to statins (odds ratio [OR]: 0.56; 95% confidence interval: 0.29-1.08) was found, which did not become stronger after adjustment for confounding factors. These observations lead us to suspect survivor bias. To identify this bias, results were stratified on time between bleeding event and inclusion, and repeated for a negative control (an exposure not related to survival): blood group non-O. The ORs for exposure to statins increased gradually to 1.37 with shorter time between outcome and inclusion, whereas ORs for the negative control remained constant, confirming our hypothesis. We recommend the presented method to check for overoptimistic results, that is, survivor bias in case-control studies. Copyright © 2014 Elsevier Inc. All rights reserved.

The Mortality Penalty of Incarceration: Evidence from a Population-based Case-control Study of Working-age Males.

PubMed

Pridemore, William Alex

2014-06-01

There is a growing body of research on the effects of incarceration on health, though there are few studies in the sociological literature of the association between incarceration and premature mortality. This study examined the risk of male premature mortality associated with incarceration. Data came from the Izhevsk (Russia) Family Study, a large-scale population-based case-control design. Cases (n = 1,750) were male deaths aged 25 to 54 in Izhevsk between October 2003 and October 2005. Controls (n = 1,750) were selected at random from a city population register. The key independent variable was lifetime prevalence of incarceration. I used logistic regression to estimate mortality odds ratios, controlling for age, hazardous drinking, smoking status, marital status, and education. Seventeen percent of cases and 5 percent of controls had been incarcerated. Men who had been incarcerated were more than twice as likely as those who had not to experience premature mortality (odds ratio = 2.2, 95 percent confidence interval: 1.6-3.0). Relative to cases with no prior incarceration, cases who had been incarcerated were more likely to die from infectious diseases, respiratory diseases, non-alcohol-related accidental poisonings, and homicide. Taken together with other recent research, these results from a rigorous case-control design reveal not only that incarceration has durable effects on illness, but that its consequences extend to a greater risk of early death. I draw on the sociology of health literature on exposure, stress, and social integration to speculate about the reasons for this mortality penalty of incarceration. © American Sociological Association 2014.

Night work and breast cancer: a population-based case-control study in France (the CECILE study).

PubMed

Menegaux, Florence; Truong, Thérèse; Anger, Antoinette; Cordina-Duverger, Emilie; Lamkarkach, Farida; Arveux, Patrick; Kerbrat, Pierre; Févotte, Joëlle; Guénel, Pascal

2013-02-15

Night work involving disruption of circadian rhythm was suggested as a possible cause of breast cancer. We examined the role of night work in a large population-based case-control study carried out in France between 2005 and 2008. Lifetime occupational history including work schedules of each night work period was elicited in 1,232 cases of breast cancer and 1,317 population controls. Thirteen percent of the cases and 11% of the controls had ever worked on night shifts (OR = 1.27 [95% confidence interval = 0.99-1.64]). Odds ratios were 1.35 [1.01-1.80] in women who worked on overnight shifts, 1.40 [1.01-1.92] in women who had worked at night for 4.5 or more years, and 1.43 [1.01-2.03] in those who worked less than three nights per week on average. The odds ratio was 1.95 [1.13-3.35] in women employed in night work for >4 years before their first full-term pregnancy, a period where mammary gland cells are incompletely differentiated and possibly more susceptible to circadian disruption effects. Our results support the hypothesis that night work plays a role in breast cancer, particularly in women who started working at night before first full-term pregnancy. Copyright © 2012 UICC.

Research participation experiences of informants of suicide and control cases: taken from a case-control psychological autopsy study of people who died by suicide.

PubMed

Wong, Paul W C; Chan, Wincy S C; Beh, Philip S L; Yau, Fiona W S; Yip, Paul S F; Hawton, Keith

2010-01-01

Ethical issues have been raised about using the psychological autopsy approach in the study of suicide. The impact on informants of control cases who participated in case-control psychological autopsy studies has not been investigated. (1) To investigate whether informants of suicide cases recruited by two approaches (coroners' court and public mortuaries) respond differently to the initial contact by the research team. (2) To explore the reactions, reasons for participation, and comments of both the informants of suicide and control cases to psychological autopsy interviews. (3) To investigate the impact of the interviews on informants of suicide cases about a month after the interviews. A self-report questionnaire was used for the informants of both suicide and control cases. Telephone follow-up interviews were conducted with the informants of suicide cases. The majority of the informants of suicide cases, regardless of the initial route of contact, as well as the control cases were positive about being approached to take part in the study. A minority of informants of suicide and control cases found the experience of talking about their family member to be more upsetting than expected. The telephone follow-up interviews showed that none of the informants of suicide cases reported being distressed by the psychological autopsy interviews. The acceptance rate for our original psychological autopsy study was modest. The findings of this study are useful for future participants and researchers in measuring the potential benefits and risks of participating in similar sensitive research. Psychological autopsy interviews may be utilized as an active engagement approach to reach out to the people bereaved by suicide, especially in places where the postvention work is underdeveloped.

RACORO Continental Boundary Layer Cloud Investigations: 1. Case Study Development and Ensemble Large-Scale Forcings

NASA Technical Reports Server (NTRS)

Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang;

RACORO continental boundary layer cloud investigations: 1. Case study development and ensemble large-scale forcings

NASA Astrophysics Data System (ADS)

Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; Li, Zhijin; Xie, Shaocheng; Ackerman, Andrew S.; Zhang, Minghua; Khairoutdinov, Marat

2015-06-01

Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60 h case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in situ measurements from the Routine AAF (Atmospheric Radiation Measurement (ARM) Aerial Facility) CLOWD (Clouds with Low Optical Water Depth) Optical Radiative Observations (RACORO) field campaign and remote sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be 0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing data sets are derived from the ARM variational analysis, European Centre for Medium-Range Weather Forecasts, and a multiscale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in "trial" large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.

Risk factors in lateral epicondylitis (tennis elbow): a case-control study.

PubMed

Titchener, A G; Fakis, A; Tambe, A A; Smith, C; Hubbard, R B; Clark, D I

2013-02-01

Lateral epicondylitis is a common condition, but relatively little is known about its aetiology and associated risk factors. We have undertaken a large case-control study using The Health Improvement Network database to assess and quantify the relative contributions of some constitutional and environmental risk factors for lateral epicondylitis in the community. Our dataset included 4998 patients with lateral epicondylitis who were individually matched with a single control by age, sex, and general practice. The median age at diagnosis was 49 (interquartile range 42-56) years . Multivariate analysis showed that the risk factors associated with lateral epicondylitis were rotator cuff pathology (OR 4.95), De Quervain's disease (OR 2.48), carpal tunnel syndrome (OR 1.50), oral corticosteroid therapy (OR 1.68), and previous smoking history (OR 1.20). Diabetes mellitus, current smoking, trigger finger, rheumatoid arthritis, alcohol intake, and obesity were not found to be associated with lateral epicondylitis.

Bayes and empirical Bayes methods for reduced rank regression models in matched case-control studies.

PubMed

Satagopan, Jaya M; Sen, Ananda; Zhou, Qin; Lan, Qing; Rothman, Nathaniel; Langseth, Hilde; Engel, Lawrence S

2016-06-01

Matched case-control studies are popular designs used in epidemiology for assessing the effects of exposures on binary traits. Modern studies increasingly enjoy the ability to examine a large number of exposures in a comprehensive manner. However, several risk factors often tend to be related in a nontrivial way, undermining efforts to identify the risk factors using standard analytic methods due to inflated type-I errors and possible masking of effects. Epidemiologists often use data reduction techniques by grouping the prognostic factors using a thematic approach, with themes deriving from biological considerations. We propose shrinkage-type estimators based on Bayesian penalization methods to estimate the effects of the risk factors using these themes. The properties of the estimators are examined using extensive simulations. The methodology is illustrated using data from a matched case-control study of polychlorinated biphenyls in relation to the etiology of non-Hodgkin's lymphoma. © 2015, The International Biometric Society.

Risk factors for pneumonic and ulceroglandular tularaemia in Finland: a population-based case-control study.

PubMed

Rossow, H; Ollgren, J; Klemets, P; Pietarinen, I; Saikku, J; Pekkanen, E; Nikkari, S; Syrjälä, H; Kuusi, M; Nuorti, J P

2014-10-01

Few population-based data are available on factors associated with pneumonic and ulceroglandular type B tularaemia. We conducted a case-control study during a large epidemic in 2000. Laboratory-confirmed case patients were identified through active surveillance and matched control subjects (age, sex, residency) from the national population information system. Data were collected using a self-administered questionnaire. A conditional logistic regression model addressing missing data with Bayesian full-likelihood modelling included 227 case patients and 415 control subjects; reported mosquito bites [adjusted odds ratio (aOR) 9·2, 95% confidence interval (CI) 4·4-22, population-attributable risk (PAR) 82%] and farming activities (aOR 4·3, 95% CI 2·5-7·2, PAR 32%) were independently associated with ulceroglandular tularaemia, whereas exposure to hay dust (aOR 6·6, 95% CI 1·9-25·4, PAR 48%) was associated with pneumonic tularaemia. Although the bulk of tularaemia type B disease burden is attributable to mosquito bites, risk factors for ulceroglandular and pneumonic forms of tularaemia are different, enabling targeting of prevention efforts accordingly.

Plasma carotenoids, retinol, and tocopherols and postmenopausal breast cancer risk in the Multiethnic Cohort Study: a nested case-control study

PubMed Central

Epplein, Meira; Shvetsov, Yurii B; Wilkens, Lynne R; Franke, Adrian A; Cooney, Robert V; Le Marchand, Loïc; Henderson, Brian E; Kolonel, Laurence N; Goodman, Marc T

2009-01-01

Introduction Assessments by the handful of prospective studies of the association of serum antioxidants and breast cancer risk have yielded inconsistent results. This multiethnic nested case-control study sought to examine the association of plasma carotenoids, retinol, and tocopherols with postmenopausal breast cancer risk. Methods From the biospecimen subcohort of the Multiethnic Cohort Study, 286 incident postmenopausal breast cancer cases were matched to 535 controls on age, sex, ethnicity, study location (Hawaii or California), smoking status, date/time of collection and hours of fasting. We measured prediagnostic circulating levels of individual carotenoids, retinol, and tocopherols. Conditional logistic regression was used to compute odds ratios and 95% confidence intervals. Results Women with breast cancer tended to have lower levels of plasma carotenoids and tocopherols than matched controls, but the differences were not large or statistically significant and the trends were not monotonic. No association was seen with retinol. A sensitivity analysis excluding cases diagnosed within 1 year after blood draw did not alter the findings. Conclusions The lack of significant associations in this multiethnic population is consistent with previously observed results from less racially-diverse cohorts and serves as further evidence against a causal link between plasma micronutrient concentrations and postmenopausal breast cancer risk. PMID:19619335

Tuberculosis stigma in Gezira State, Sudan: a case-control study.

PubMed

Ahmed Suleiman, M M; Sahal, N; Sodemann, M; El Sony, A; Aro, A R

2013-03-01

To evaluate the prevalence of tuberculosis (TB) stigma and to determine the relation between socio-demographic characteristics and TB stigma among TB cases and their controls in Gezira State, Sudan. A case-control study design was used. New smear-positive TB patients registered in Gezira State in 2010 (n = 425) and controls who attended the same health facility for other reasons (n < 850) formed the study population. Stigma was measured using a standard modified World Health Organization TB KAP (knowledge, attitudes, practice) instrument. TB stigma did not differ between TB cases and controls; mild stigma was found in both groups. The higher degree of stigma among both groups was significantly associated with higher age, lower level of education, residence in rural areas, unemployment and poor TB awareness, while sex had no association with the degree of stigma in either group. Although TB stigma among the Gezira population was found to be mild, it can affect treatment adherence. Empowering both TB patients and communities by increasing their knowledge through proper education programmes could effectively contribute to the effort of controlling TB in the state.

Case Study: Mini-Case Studies: Small Infusions of Active Learning for Large-Lecture Courses

ERIC Educational Resources Information Center

Carloye, Lisa

2017-01-01

In this article, the author introduces the usage of case studies to be an excellent method for engaging students through stories. The author notes she developed a series of mini-case studies that can be implemented, with a little advance preparation, within a 10- to 15-minute window during lecture. What makes them "mini" case studies?…

Laryngospasm during emergency department ketamine sedation: a case-control study.

PubMed

Green, Steven M; Roback, Mark G; Krauss, Baruch

2010-11-01

The objective of this study was to assess predictors of emergency department (ED) ketamine-associated laryngospasm using case-control techniques. We performed a matched case-control analysis of a sample of 8282 ED ketamine sedations (including 22 occurrences of laryngospasm) assembled from 32 prior published series. We sequentially studied the association of each of 7 clinical variables with laryngospasm by assigning 4 controls to each case while matching for the remaining 6 variables. We then used univariate statistics and conditional logistic regression to analyze the matched sets. We found no statistical association of age, dose, oropharyngeal procedure, underlying physical illness, route, or coadministered anticholinergics with laryngospasm. Coadministered benzodiazepines showed a borderline association in the multivariate but not univariate analysis that was considered anomalous. This case-control analysis of the largest available sample of ED ketamine-associated laryngospasm did not demonstrate evidence of association with age, dose, or other clinical factors. Such laryngospasm seems to be idiosyncratic, and accordingly, clinicians administering ketamine must be prepared for its rapid identification and management. Given no evidence that they decrease the risk of laryngospasm, coadministered anticholinergics seem unnecessary.

A case-control study of diesel exhaust exposure and bladder cancer.

PubMed

Wynder, E L; Dieck, G S; Hall, N E; Lahti, H

1985-08-01

The relationship between bladder cancer and employment in occupations involving exposure to diesel exhaust was examined using data from a hospital-based case-control study of men aged 20 to 80 years in 18 hospitals in six U.S. cities, from January 1981 to May 1983. In this analysis, 194 cases and 582 controls were compared according to occupation, smoking history, alcohol and coffee consumption, and various demographic variables. No difference was found in the proportion of bladder cancer cases employed in occupations with exposure to diesel exhaust compared to controls. This relationship did not change after taking smoking habits into account. Bladder cancer cases were significantly more likely to be current smokers of cigarettes than were controls.

Conceiving semi-active control devices for large-size monolithic monuments

NASA Astrophysics Data System (ADS)

Casciati, Fabio; El Attar, Adel; Casciati, Sara

2001-07-01

CHIME is a research project, funded by the European Union, which investigates the adoption of innovative structural control techniques in view of the seismic rehabilitation of the wide monumental cultural heritage in Mediterranean countries as Egypt, Tunisia and Cyprus. The structural control devices are mainly of the semi-active type. In this particular paper one reports the first results achieved within a case study. It considers an Egyptian large size monolithic monument. Alternative solutions for its seismic rehabilitation are eventually conceived and discussed.

Analysis of Clinical Cohort Data Using Nested Case-control and Case-cohort Sampling Designs. A Powerful and Economical Tool.

PubMed

Ohneberg, K; Wolkewitz, M; Beyersmann, J; Palomar-Martinez, M; Olaechea-Astigarraga, P; Alvarez-Lerma, F; Schumacher, M

2015-01-01

Sampling from a large cohort in order to derive a subsample that would be sufficient for statistical analysis is a frequently used method for handling large data sets in epidemiological studies with limited resources for exposure measurement. For clinical studies however, when interest is in the influence of a potential risk factor, cohort studies are often the first choice with all individuals entering the analysis. Our aim is to close the gap between epidemiological and clinical studies with respect to design and power considerations. Schoenfeld's formula for the number of events required for a Cox' proportional hazards model is fundamental. Our objective is to compare the power of analyzing the full cohort and the power of a nested case-control and a case-cohort design. We compare formulas for power for sampling designs and cohort studies. In our data example we simultaneously apply a nested case-control design with a varying number of controls matched to each case, a case cohort design with varying subcohort size, a random subsample and a full cohort analysis. For each design we calculate the standard error for estimated regression coefficients and the mean number of distinct persons, for whom covariate information is required. The formula for the power of a nested case-control design and the power of a case-cohort design is directly connected to the power of a cohort study using the well known Schoenfeld formula. The loss in precision of parameter estimates is relatively small compared to the saving in resources. Nested case-control and case-cohort studies, but not random subsamples yield an attractive alternative for analyzing clinical studies in the situation of a low event rate. Power calculations can be conducted straightforwardly to quantify the loss of power compared to the savings in the num-ber of patients using a sampling design instead of analyzing the full cohort.

What factors play a role in preventing self-immolation? Results from a case-control study in Iran

PubMed Central

Karim, Hosein; Schwebel, David C.; Bazargan-Hejazi, Shahrzad; Mohammadi, Reza; Choubsaz, Mansour; Heidari Zadie, Zahra; Ahmadi, Alireza

2015-01-01

Abstract: Background: To investigate factors related to prevention of self-immolation in west of Iran. Methods: In a case-control study, 30 consecutive cases of deliberate self-inflicted burns admitted to the regional burn center (Imam Khomeini hospital in Kermanshah province, Iran) were compared with controls selected from the community and matched by sex, age, district-county of residence, and rural vs urban living environment. The following characteristics relevant to preventing self-immolation were collected from all cases and controls: main domestic fuel used in the household, awareness about complications of burn injuries, and use of counseling services. Results: Descriptive analyses revealed that kerosene was the main domestic fuel in the household for 83% of cases. Not surprisingly, the main means of self-immolation in 93% of the patients was kerosene, with other fuels such as petrol and domestic gas used in remaining cases. The majority of cases and controls were aware of the potential complications of burn injuries. Use of counseling services was more common in controls. Conclusions: All three aspects of preventing self-immolation – having kerosene and other fuels in the home, being aware of the complications of burn injuries, and using counseling services were present in both the cases and controls. This suggests a large portion of residents in rural Iran are potential self-immolation victims. Increasing preventive strategies may reduce risk of suicide by self-immolation. PMID:26081518

Bias correction of risk estimates in vaccine safety studies with rare adverse events using a self-controlled case series design.

PubMed

Zeng, Chan; Newcomer, Sophia R; Glanz, Jason M; Shoup, Jo Ann; Daley, Matthew F; Hambidge, Simon J; Xu, Stanley

2013-12-15

The self-controlled case series (SCCS) method is often used to examine the temporal association between vaccination and adverse events using only data from patients who experienced such events. Conditional Poisson regression models are used to estimate incidence rate ratios, and these models perform well with large or medium-sized case samples. However, in some vaccine safety studies, the adverse events studied are rare and the maximum likelihood estimates may be biased. Several bias correction methods have been examined in case-control studies using conditional logistic regression, but none of these methods have been evaluated in studies using the SCCS design. In this study, we used simulations to evaluate 2 bias correction approaches-the Firth penalized maximum likelihood method and Cordeiro and McCullagh's bias reduction after maximum likelihood estimation-with small sample sizes in studies using the SCCS design. The simulations showed that the bias under the SCCS design with a small number of cases can be large and is also sensitive to a short risk period. The Firth correction method provides finite and less biased estimates than the maximum likelihood method and Cordeiro and McCullagh's method. However, limitations still exist when the risk period in the SCCS design is short relative to the entire observation period.

Obstacles to action in arthritis: a community case-control study.

PubMed

Hutton, Ingrid; Gamble, Greg; McLean, Grant; Butcher, Hugh; Gow, Peter; Dalbeth, Nicola

2009-07-01

Despite the benefits of physical activity, people with arthritis are less active than the general population. The aim of this study was to determine the motivators and obstacles to physical activity for adults with arthritis. Participants were identified from the Obstacles to Action Study, a community based study of 8163 adults, which explored barriers and motivators to physical activity. A 1:1 case-control study was designed; cases were identified as those participants who reported arthritis (n = 1106). Each case was matched with an age, sex and ethnicity-matched non-arthritis control (n = 1106). Cases were less likely to achieve recommended physical activity targets (58.8% vs. 68.1% P = 0.00001). Furthermore, fewer people with arthritis believed that physical activity would help them lead healthy lives (86.7% vs. 91.3% P = 0.006) or viewed physical activity as a priority (53.8% vs. 59.8% P = 0.005). Cases were less confident in their abilities to try a new activity (37.1% vs. 43.7% P = 0.002) or maintain a healthy weight (65.0% vs. 74.3% P = 0.00001). Cases also reported greater negative impact scores for barriers to activity, particularly arthritis, accessibility, cost and discomfort while exercising. Motivators and environmental barriers to activity were similar for cases and controls. These findings persisted after adjusting for educational level, body mass index and comorbidities. People with arthritis are less active and demonstrate different attitudes toward physical activity. Although people with arthritis identify similar environmental barriers, they have different psychosocial barriers. In order to design effective physical activity programs for people with arthritis, these barriers must be specifically addressed.

Association of OPRD1 polymorphisms with heroin dependence in a large case-control series.

PubMed

Nelson, Elliot C; Lynskey, Michael T; Heath, Andrew C; Wray, Naomi; Agrawal, Arpana; Shand, Fiona L; Henders, Anjali K; Wallace, Leanne; Todorov, Alexandre A; Schrage, Andrew J; Madden, Pamela A F; Degenhardt, Louisa; Martin, Nicholas G; Montgomery, Grant W

2014-01-01

Genes encoding the opioid receptors (OPRM1, OPRD1 and OPRK1) are obvious candidates for involvement in risk for heroin dependence. Prior association studies commonly had samples of modest size, included limited single nucleotide polymorphism (SNP) coverage of these genes and yielded inconsistent results. Participants for the current investigation included 1459 heroin-dependent cases ascertained from maintenance clinics in New South Wales, Australia, 1495 unrelated individuals selected from an Australian sample of twins and siblings as not meeting DSM-IV criteria for lifetime alcohol or illicit drug dependence (non-dependent controls) and 531 controls ascertained from economically disadvantaged neighborhoods in proximity to the maintenance clinics. A total of 136 OPRM1, OPRD1 and OPRK1 SNPs were genotyped in this sample. After controlling for admixture with principal components analysis, our comparison of cases to non-dependent controls found four OPRD1 SNPs in fairly high linkage disequilibrium for which adjusted P values remained significant (e.g. rs2236857; OR 1.25; P=2.95×10(-4) ) replicating a previously reported association. A post hoc analysis revealed that the two SNP (rs2236857 and rs581111) GA haplotype in OPRD1 is associated with greater risk (OR 1.68; P=1.41×10(-5) ). No OPRM1 or OPRK1 SNPs reached more than nominal significance. Comparisons of cases to neighborhood controls reached only nominal significance. Our results replicate a prior report providing strong evidence implicating OPRD1 SNPs and, in particular, the two SNP (rs2236857 and rs581111) GA haplotype in liability for heroin dependence. Support was not found for similar association involving either OPRM1 or OPRK1 SNPs. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

Common mental disorders associated with tuberculosis: a matched case-control study.

PubMed

de Araújo, Gleide Santos; Pereira, Susan Martins; dos Santos, Darci Neves; Marinho, Jamocyr Moura; Rodrigues, Laura Cunha; Barreto, Mauricio Lima

2014-01-01

Despite the availability of treatment and a vaccine, tuberculosis continues to be a public health problem worldwide. Mental disorders might contribute to the burden of the disease. The objective of this study was to investigate the association between common mental disorders and tuberculosis. A matched case-control study was conducted. The study population included symptomatic respiratory patients who attended three referral hospitals and six community clinics in the city of Salvador, Brazil. A doctor's diagnosis defined potential cases and controls. Cases were newly diagnosed tuberculosis cases, and controls were symptomatic respiratory patients for whom tuberculosis was excluded as a diagnosis by the attending physician. Cases and controls were ascertained in the same clinic. Data collection occurred between August 2008 and April 2010. The study instruments included a structured interview, a self-reporting questionnaire for the identification of common mental disorders, and a questionnaire for alcoholism. An univariate analysis included descriptive procedures (with chi-square statistics), and a multivariate analysis used conditional logistic regression. The mean age of the cases was 38 years, and 61% of the cases were males. After adjusting for potential confounders, the odds of tuberculosis were significantly higher in patients diagnosed with a common mental disorder (OR: 1.34; 95% CI 1.05-1.70). There appears to be a positive and independent association between common mental disorders and tuberculosis; further epidemiological studies are required to increase our understanding of the possible biological and social mechanisms responsible for this association. Independent of the direction of the association, this finding has implications for the provision of care for mental disorders and for tuberculosis.

Drug interactions with phenprocoumon and the risk of serious haemorrhage: a nested case-control study in a large population-based German database.

PubMed

Jobski, Kathrin; Behr, Sigrid; Garbe, Edeltraut

2011-09-01

Phenprocoumon is the most frequently used vitamin K antagonist in Germany. The aim of this study was to estimate the risk of serious bleeding as a result of the use of drugs with potential interaction with phenprocoumon. We conducted a nested case-control study in a cohort of 246,220 phenprocoumon users in the German Pharmacoepidemiological Research Database. Cases were patients hospitalised for haemorrhage of different kinds. Ten controls were matched to each case by health insurance, birth year and sex using incidence density sampling. Odds ratios (OR) with 95% confidence intervals (CI) of the risk of serious bleeding associated with combined use of phenprocoumon and potentially interacting drugs versus phenprocoumon alone were estimated using conditional logistic regression analysis. Our analyses considered multiple risk factors, such as bleeding history, other comorbidities or co-medication. Our study included 2,553 cases and 25,348 matched controls. An increased risk of bleeding was observed for the combined use of phenprocoumon and clopidogrel vs phenprocoumon use alone (OR: 1.83, 95% CI: 1.41-2.36). Antibiotic drugs associated with an increased risk of haemorrhage in the population of phenprocoumon users included the group of quinolones with ORs ranging from 2.74 (95% CI: 1.80-4.18) for ciprofloxacin to 4.40 (95% CI: 2.45-7.89) for levofloxacin, amoxicillin plus clavulanic acid (OR: 2.99, 95% CI: 1.39-6.42) and cotrimoxazole (OR 3.57, 95% CI: 2.36-5.40). Among non-steroidal anti-inflammatory drugs (NSAIDs), ketoprofen and naproxen were associated with the highest risks. Significantly elevated risks of major bleeding were mainly observed for drugs with known pharmacodynamic interaction with phenprocoumon, and less for drugs with possible pharmacokinetic interaction.

RACORO continental boundary layer cloud investigations. Part I: Case study development and ensemble large-scale forcings

DOE PAGES

Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; ...

2015-06-19

Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60-hour case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in-situ measurements from the RACORO field campaign and remote-sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functionsmore » for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing datasets are derived from the ARM variational analysis, ECMWF forecasts, and a multi-scale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in 'trial' large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.« less

Cardiac glycosides use and the risk of lung cancer: a nested case-control study.

PubMed

Couraud, Sébastien; Azoulay, Laurent; Dell'Aniello, Sophie; Suissa, Samy

2014-08-08

Two studies have reported statistically significant associations between the use of cardiac glycosides (CGs) and an increased risk of lung cancer. However, these studies had a number of methodological limitations. Thus, the objective of this study was to assess this association in a large population-based cohort of patients. We used the United Kingdom Clinical Practice Research Datalink (CPRD) to identify a cohort of patients, at least 40 years of age, newly-diagnosed with heart failure, or supra-ventricular arrhythmia. A nested case-control analysis was conducted where each incident case of lung cancer identified during follow-up was randomly matched with up to 10 controls. Exposure to CGs was assessed in terms of ever use, cumulative duration of use and cumulative dose. Rate ratios (RRs) with 95% confidence intervals (CIs) were estimated using conditional logistic regression after adjusting for potential confounders. A total of 129,002 patients were included, and followed for a mean (SD) of 4.7 (3.8) years. During follow-up, 1237 patients were newly-diagnosed with lung cancer. Overall, ever use of CGs was not associated with an increased risk of lung cancer when compared to never use (RR = 1.09, 95% CI: 0.94-1.26). In addition, no dose-response relationship was observed in terms of cumulative duration of use and cumulative dose with all RRs around the null value across quartile categories. The results of this large population-based study indicate that the use of CGs is not associated with an increased risk of lung cancer.

Glioma and occupational exposure in Sweden, a case-control study.

PubMed Central

Rodvall, Y; Ahlbom, A; Spännare, B; Nise, G

1996-01-01

OBJECTIVES: The aim of the study was to analyse whether any job titles, industrial codes, and certain occupational exposures were associated with an increased risk of glioma. METHODS: A population based case-control study of incident primary brain tumours in adults was carried out in Uppsala, Sweden in the period 1987-90. The study included 192 cases of glioma and 192 matched controls. It also included cases with other tumours of the central nervous system with matched controls. Information from all 343 controls was used in this study. Information was collected by means of a questionnaire that was sent to all subjects. An occupational hygienist reviewed the questionnaires for self reported exposures to substances and assessed whether these reported exposures were plausible or not in the corresponding occupation. RESULTS: The kappa coefficient for those classified by the two methods ranged between 0.46 and 0.88, and they were almost the same for cases and controls. For men exposed to solvents a relative risk (RR) of 2.6 (95% CI 1.3 to 5.2) was found. For men exposed to pesticides the RR was 1.8 (95% CI 0.6 to 5.1), and for plastic materials the RR was 3.6 (95% CI 1.0 to 12.4). For men employed in forestry and logging the RR was 2.2 (95% CI 0.9 to 5.3) and in basic metal industries 2.0 (95% CI 1.0 to 4.0). CONCLUSION: An increased risk of glioma was associated with use of solvents, pesticides, and plastic materials but this should be interpreted with some caution. PMID:8983463

Response rates in case-control studies of cancer by era of fieldwork and by characteristics of study design.

PubMed

Xu, Mengting; Richardson, Lesley; Campbell, Sally; Pintos, Javier; Siemiatycki, Jack

2018-04-09

The purpose of this study was to describe time trends in response rates in case-control studies of cancer and identify study design factors that influence response rate. We reviewed 370 case-control studies of cancer published in 12 journals during indicator years in each of the last four decades. We estimated time trends of response rates and reasons for nonresponse in each of the following types of study subjects: cases, medical source controls, and population controls. We also estimated response rates according to characteristics of study context. Median response rates among cases and population controls were between 75% and 80% in the 1970s. Between 1971 and 2010, study response rates declined by 0.31% per year for cases and 0.78% for population controls. Only a minority of studies reported reasons for nonparticipation; subject refusal was the most common reported reason. Studies conducted in North America had lower median response rates than studies conducted in Europe. In-person and telephone interviews elicited higher response rates than mail questionnaires. Response rates from case-control studies of cancer have declined, and this could threaten the validity of results derived from these studies. Copyright © 2018 Elsevier Inc. All rights reserved.

Pain Sensitivity Risk Factors for Chronic TMD: Descriptive Data and Empirically Identified Domains from the OPPERA Case Control Study

PubMed Central

Greenspan, Joel D.; Slade, Gary D.; Bair, Eric; Dubner, Ronald; Fillingim, Roger B.; Ohrbach, Richard; Knott, Charlie; Mulkey, Flora; Rothwell, Rebecca; Maixner, William

2011-01-01

Many studies report that people with temporomandibular disorders (TMD) are more sensitive to experimental pain stimuli than TMD-free controls. Such differences in sensitivity are observed in remote body sites as well as in the orofacial region, suggesting a generalized upregulation of nociceptive processing in TMD cases. This large case-control study of 185 adults with TMD and 1,633 TMD-free controls measured sensitivity to painful pressure, mechanical cutaneous, and heat stimuli, using multiple testing protocols. Based on an unprecedented 36 experimental pain measures, 28 showed statistically significantly greater pain sensitivity in TMD cases than controls. The largest effects were seen for pressure pain thresholds at multiple body sites and cutaneous mechanical pain threshold. The other mechanical cutaneous pain measures and many of the heat pain measures showed significant differences, but with lesser effect sizes. Principal component analysis (PCA) of the pain measures derived from 1,633 controls identified five components labeled: (1) heat pain ratings, (2) heat pain aftersensations and tolerance, (3) mechanical cutaneous pain sensitivity, (4) pressure pain thresholds, and (5) heat pain temporal summation. These results demonstrate that, compared to TMD-free controls, chronic TMD cases are more sensitive to many experimental noxious stimuli at extra-cranial body sites, and provides for the first time the ability to directly compare the case-control effect sizes of a wide range of pain sensitivity measures. PMID:22074753

Diagnostic Performance and Utility of Quantitative EEG Analyses in Delirium: Confirmatory Results From a Large Retrospective Case-Control Study.

PubMed

Fleischmann, Robert; Tränkner, Steffi; Bathe-Peters, Rouven; Rönnefarth, Maria; Schmidt, Sein; Schreiber, Stephan J; Brandt, Stephan A

2018-03-01

The lack of objective disease markers is a major cause of misdiagnosis and nonstandardized approaches in delirium. Recent studies conducted in well-selected patients and confined study environments suggest that quantitative electroencephalography (qEEG) can provide such markers. We hypothesize that qEEG helps remedy diagnostic uncertainty not only in well-defined study cohorts but also in a heterogeneous hospital population. In this retrospective case-control study, EEG power spectra of delirious patients and age-/gender-matched controls (n = 31 and n = 345, respectively) were fitted in a linear model to test their performance as binary classifiers. We subsequently evaluated the diagnostic performance of the best classifiers in control samples with normal EEGs (n = 534) and real-world samples including pathologic findings (n = 4294). Test reliability was estimated through split-half analyses. We found that the combination of spectral power at F3-P4 at 2 Hz (area under the curve [AUC] = .994) and C3-O1 at 19 Hz (AUC = .993) provided a sensitivity of 100% and a specificity of 99% to identify delirious patients among normal controls. These classifiers also yielded a false positive rate as low as 5% and increased the pretest probability of being delirious by 57% in an unselected real-world sample. Split-half reliabilities were .98 and .99, respectively. This retrospective study yielded preliminary evidence that qEEG provides excellent diagnostic performance to identify delirious patients even outside confined study environments. It furthermore revealed reduced beta power as a novel specific finding in delirium and that a normal EEG excludes delirium. Prospective studies including parameters of pretest probability and delirium severity are required to elaborate on these promising findings.

Violence against Women and Gastroschisis: A Case-Control Study

PubMed Central

Ortega-García, Juan Antonio; Soldin, Offie P.; Sánchez-Sauco, Miguel Felipe; Cánovas-Conesa, Alicia; Gomaríz-Peñalver, Virtudes; Jaimes-Vega, Diana Carolina; Perales, Joseph E.; Cárceles-Alvarez, Alberto; Martínez-Ros, Maria Teresa; Ruiz, Daniel

2013-01-01

Background: Gastroschisis, a birth defect characterized by herniated fetal abdominal wall, occurs more commonly in infants born to teenage and young mothers. Ischemia of the vascular vitelline vessels is the likely mechanism of pathogenesis. Given that chronic stress and violence against women are risk factors for cardiovascular disease we explored whether these may represent risk factors for gastroschisis, when they occur during pregnancy. A case-control study was conducted, with 15 incident cases of children born with gastroschisis in the Region of Murcia, Spain, from December 2007 to June 2013. Forty concurrent controls were recruited at gestation weeks 20–24 or post-partum. All mothers of cases and controls completed a comprehensive, in-person, ‘green sheet’ questionnaire on environmental exposures. Results: Mothers of children with gastroschisis were younger, smoked more cigarettes per week relative to controls, were exposed to higher amounts of illegal drugs, and suffered from domestic violence more frequently than the controls. Multivariable logistic regression analysis highlights periconceptional ‘gender-related violence’ (OR: 16.6, 95% CI 2.7 to 101.7) and younger maternal age (OR 1.1, 95% CI 1.0–1.3). Conclusions: Violence against pregnant women is associated with birth defects, and should be studied in more depth as a cause-effect teratogenic. Psychosocial risk factors, including gender-based violence, are important for insuring the health and safety of the pregnant mother and the fetus. PMID:24142184

Sample size calculations for case-control studies

Cancer.gov

This R package can be used to calculate the required samples size for unconditional multivariate analyses of unmatched case-control studies. The sample sizes are for a scalar exposure effect, such as binary, ordinal or continuous exposures. The sample sizes can also be computed for scalar interaction effects. The analyses account for the effects of potential confounder variables that are also included in the multivariate logistic model.

Drug and alcohol crash risk : a case-control study.

DOT National Transportation Integrated Search

2016-12-01

This study used a case-control design to estimate the risk of crashes involving drivers using drugs, alcohol or both. Data was collected in Virginia Beach, Virginia, for 20 months. The study obtained biological measures on more than 3,000 crash...

Controls on water use for thermoelectric generation: case study Texas, US.

PubMed

Scanlon, Bridget R; Reedy, Robert C; Duncan, Ian; Mullican, William F; Young, Michael

2013-10-01

Large-scale U.S. dependence on thermoelectric (steam electric) generation requiring water for cooling underscores the need to understand controls on this water use. The study objective was to quantify water consumption and withdrawal for thermoelectric generation, identifying controls, using Texas as a case study. Water consumption for thermoelectricity in Texas in 2010 totaled ∼0.43 million acre feet (maf; 0.53 km(3)), accounting for ∼4% of total state water consumption. High water withdrawals (26.2 maf, 32.3 km(3)) mostly reflect circulation between ponds and power plants, with only two-thirds of this water required for cooling. Controls on water consumption include (1) generator technology/thermal efficiency and (2) cooling system, resulting in statewide consumption intensity for natural gas combined cycle generators with mostly cooling towers (0.19 gal/kWh) being 63% lower than that of traditional coal, nuclear, or natural gas steam turbine generators with mostly cooling ponds (0.52 gal/kWh). The primary control on water withdrawals is cooling system, with ∼2 orders of magnitude lower withdrawals for cooling towers relative to once-through ponds statewide. Increases in natural gas combined cycle plants with cooling towers in response to high production of low-cost natural gas has greatly reduced water demand for thermoelectric cooling since 2000.

Study designs may influence results: the problems with questionnaire-based case-control studies on the epidemiology of glioma.

PubMed

Johansen, Christoffer; Schüz, Joachim; Andreasen, Anne-Marie Serena; Dalton, Susanne Oksbjerg

2017-03-28

Glioma is a rare brain tumour with a very poor prognosis and the search for modifiable factors is intense. We reviewed the literature concerning risk factors for glioma obtained in case-control designed epidemiological studies in order to discuss the influence of this methodology on the observed results. When reviewing the association between three exposures, medical radiation, exogenous hormone use and allergy, we critically appraised the evidence from both case-control and cohort studies. For medical radiation and hormone replacement therapy (HRT), questionnaire-based case-control studies appeared to show an inverse association, whereas nested case-control and cohort studies showed no association. For allergies, the inverse association was observed irrespective of study design. We recommend that the questionnaire-based case-control design be placed lower in the hierarchy of studies for establishing cause-and-effect for diseases such as glioma. We suggest that a state-of-the-art case-control study should, as a minimum, be accompanied by extensive validation of the exposure assessment methods and the representativeness of the study sample with regard to the exposures of interest. Otherwise, such studies cannot be regarded as 'hypothesis testing' but only 'hypothesis generating'. We consider that this holds true for all questionnaire-based case-control studies on cancer and other chronic diseases, although perhaps not to the same extent for each exposure-outcome combination.

Risk factors for gallbladder cancer: a case-control study.

PubMed

Jain, Kajal; Sreenivas, V; Velpandian, T; Kapil, Umesh; Garg, Pramod Kumar

2013-04-01

Risk factors for gallbladder cancer (GBC) except gallstones are not well known. The objective was to study the risk factors for GBC. In a case-control study, 200 patients with GBC, 200 healthy controls and 200 gallstones patients as diseased controls were included prospectively. The risk factors studied were related to socioeconomic profile, life style, reproduction, diet and bile acids. On comparing GBC patients (mean age 51.7 years; 130 females) with healthy controls, risk factors were chemical exposure [odd ratios (OR): 7.0 (2.7-18.2); p < 0.001)], family history of gallstones [OR: 5.3 (1.5-18.9); p < 0.01)], tobacco [OR: 4.1 (1.8-9.7); p < 0.001)], fried foods [OR: 3.1 (1.7-5.6); p < 0.001], joint family [OR: 3.2 (1.7-6.2); p < 0.001], long interval between meals [OR: 1.4 (1.2-1.6); p < 0.001] and residence in Gangetic belt [OR: 3.3 (1.8-6.2); p < 0.001]. On comparing GBC cases with gallstone controls, risk factors were female gender [OR: 2.4 (1.3-4.3); p = 0.004], residence in Gangetic belt [OR: 2.3 (1.2-4.4); p = 0.012], fried foods [OR: 2.5 (1.4-4.4); p < 0.001], diabetes [OR: 2.7 (1.2-6.4); p = 0.02)], tobacco [OR 3.8 (1.7-8.1); p < 0.001)] and joint family [OR: 2.1 (1.2-3.4); p = 0.004]. The ratio of secondary to primary bile acids was significantly higher in GBC cases than gallstone controls (20.8 vs. 0.44). Fried foods, tobacco, chemical exposure, family history of gallstones, residence in Gangetic belt and secondary bile acids were significant risk factors for GBC. Copyright © 2012 UICC.

Control-oriented modelization of a satellite with large flexible appendages and use of worst-case analysis to verify robustness to model uncertainties of attitude control

NASA Astrophysics Data System (ADS)

Gasbarri, Paolo; Monti, Riccardo; Campolo, Giovanni; Toglia, Chiara

2012-12-01

The design of large space structures (LSS) requires the use of design and analysis tools that include different disciplines. For such a kind of spacecrafts it is in fact mandatory that mechanical design and guidance navigation and control (GNC) design are developed within a common framework. One of the key-points in the development of LSS is related to the dynamic phenomena. These phenomena usually lead to two different interpretations. The former one is related to the overall motion of the spacecraft, i.e., the motion of the centre of gravity and motion around the centre of gravity. The latter one is related to the local motion of the elastic elements that leads to oscillations. These oscillations have in turn a disturbing effect on the motion of the spacecraft. From an engineering perspective, the structural model of flexible spacecrafts is generally obtained via FEM involving thousands of degrees of freedom (DOFs). Many of them are not significant from the attitude control point of view. One of the procedures to reduce the structural DOFs is tied to the modal decomposition technique. In the present paper a technique to develop a control-oriented structural model will be proposed. Starting from a detailed FE model of the spacecraft and using a special modal condensation approach, a continuous model is defined. With this transformation the number of DOFs necessary to study the coupled elastic/rigid dynamic is reduced. The final dynamic model will be suitable for the control design implementation. In order to properly design a satellite controller, it is important to recall that the characteristic parameters of the satellite are uncertain. The effect that uncertainties have on control performance must be investigated. A possible solution is that, after the attitude controller is designed on the nominal model, a Verification and Validation (V&V) process is performed to guarantee a correct functionality under a large number of scenarios. The V&V process can be very

Case-Control Studies of Sporadic Enteric Infections: A Review and Discussion of Studies Conducted Internationally from 1990 to 2009

PubMed Central

Fullerton, Kathleen E.; Scallan, Elaine; Kirk, Martyn D.; Mahon, Barbara E.; Angulo, Frederick J.; de Valk, Henriette; van Pelt, Wilfrid; Gauci, Charmaine; Hauri, Anja M.; Majowicz, Shannon; O’Brien, Sarah J.

2015-01-01

Epidemiologists have used case-control studies to investigate enteric disease outbreaks for many decades. Increasingly, case-control studies are also used to investigate risk factors for sporadic (not outbreak-associated) disease. While the same basic approach is used, there are important differences between outbreak and sporadic disease settings that need to be considered in the design and implementation of the case-control study for sporadic disease. Through the International Collaboration on Enteric Disease “Burden of Illness” Studies (the International Collaboration), we reviewed 79 case-control studies of sporadic enteric infections caused by nine pathogens that were conducted in 22 countries and published from 1990 through to 2009. We highlight important methodological and study design issues (including case definition, control selection, and exposure assessment) and discuss how approaches to the study of sporadic enteric disease have changed over the last 20 years (e.g., making use of more sensitive case definitions, databases of controls, and computer-assisted interviewing). As our understanding of sporadic enteric infections grows, methods and topics for case-control studies are expected to continue to evolve; for example, advances in understanding of the role of immunity can be used to improve control selection, the apparent protective effects of certain foods can be further explored, and case-control studies can be used to provide population-based measures of the burden of disease. PMID:22443481

Association between biomass fuel and pulmonary tuberculosis: a nested case-control study.

PubMed

Kolappan, C; Subramani, R

2009-08-01

To quantify the association between biomass fuel usage and sputum-positive pulmonary tuberculosis. A tuberculosis prevalence survey was conducted in a random sample of 50 rural units (villages) and three urban units in the Tiruvallur district of Tamilnadu, India during the period 2001-2003. Additional data regarding exposure to tobacco smoking, alcohol consumption, biomass fuel usage and Standard of Living Index (SLI) were also collected from the study participants. A nested case-control study was carried out in this population. Cases are defined as bacteriological-positive cases diagnosed by either sputum smear or culture examination. For each case, five age- (within +/-5 years of age) and sex-matched controls were selected randomly from the non-cases residing in the same village/unit. Thus, 255 cases and 1275 controls were included in this study. The unadjusted OR measured from univariate analysis for biomass fuel is 2.9 (95% CI 1.8 to 4.7). The adjusted OR measured from multivariate analysis using Cox regression is 1.7 (95% CI 1.0 to 2.9). Thirty-six percent of cases are attributable to biomass fuel usage. The findings from this case-control study add to the evidence for an independent association between biomass smoke and pulmonary tuberculosis. Improvement in standards of living brought about by economic development will lead to more people using cleaner fuels for cooking than biomass fuel which in turn will lead to a reduction in the occurrence of pulmonary tuberculosis in the community.

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.

A modified case-control study of cryptosporidiosis (using non-Cryptosporidium-infected enteric cases as controls) in a community setting.

PubMed

Pintar, K D M; Pollari, F; Waltner-Toews, D; Charron, D F; McEwen, S A; Fazil, A; Nesbitt, A

2009-12-01

Data from the first sentinel site (Waterloo Region, Ontario) of the Canadian Integrated Enteric Disease Surveillance System (C-EnterNet) were used in a secondary-based case-control study of laboratory-confirmed Cryptosporidium infections to study the role of various exposure factors. The incidence of cryptosporidiosis in Waterloo Region was almost double both the provincial and national rates. Persons ill with one of nine other enteric infections (amoebiasis, campylobacteriosis, cyclosporiasis, giardiasis, listeriosis, salmonellosis, shigellosis, verotoxigenic E. coli infections, yersiniosis) captured by the surveillance system were used as the control group. Of 1204 cases of enteric illness in the sentinel area between April 2005 and December 2007, 36 cases and 803 controls were selected after excluding outbreak and international travel-related cases. Univariable analyses (Pearson chi2 and Fisher's exact tests) and multivariable logistic regression were performed. Results of the multivariable analysis found that cryptosporidiosis was associated with swimming in a lake or river (OR 2.9, 95% CI 1.2-7.4), drinking municipal water (a potential surrogate for urban respondents vs. rural) (OR 2.4, 95% CI 1.04-5.7), and having a family member with a diarrhoeal illness (OR 2.9, 95% CI 1.3-6.4).

Comparison of Estimates between Cohort and Case-Control Studies in Meta-Analyses of Therapeutic Interventions: A Meta-Epidemiological Study.

PubMed

Lanza, Amy; Ravaud, Philippe; Riveros, Carolina; Dechartres, Agnes

2016-01-01

Observational studies are increasingly being used for assessing therapeutic interventions. Case-control studies are generally considered to have greater risk of bias than cohort studies, but we lack evidence of differences in effect estimates between the 2 study types. We aimed to compare estimates between cohort and case-control studies in meta-analyses of observational studies of therapeutic interventions by using a meta-epidemiological study. We used a random sample of meta-analyses of therapeutic interventions published in 2013 that included both cohort and case-control studies assessing a binary outcome. For each meta-analysis, the ratio of estimates (RE) was calculated by comparing the estimate in case-control studies to that in cohort studies. Then, we used random-effects meta-analysis to estimate a combined RE across meta-analyses. An RE < 1 indicated that case-control studies yielded larger estimates than cohort studies. The final analysis included 23 meta-analyses: 138 cohort and 133 case-control studies. Treatment effect estimates did not significantly differ between case-control and cohort studies (combined RE 0.97 [95% CI 0.86-1.09]). Heterogeneity was low, with between-meta-analysis variance τ2 = 0.0049. Estimates did not differ between case-control and prospective or retrospective cohort studies (RE = 1.05 [95% CI 0.96-1.15] and RE = 0.99 [95% CI, 0.83-1.19], respectively). Sensitivity analysis of studies reporting adjusted estimates also revealed no significant difference (RE = 1.03 [95% CI 0.91-1.16]). Heterogeneity was also low for these analyses. We found no significant difference in treatment effect estimates between case-control and cohort studies assessing therapeutic interventions.

Brain-relevant antibodies in first-episode psychosis: a matched case-control study.

PubMed

Gaughran, Fiona; Lally, John; Beck, Katherine; McCormack, Ruaidhri; Gardner-Sood, Poonam; Coutinho, Ester; Jacobson, Leslie; Lang, Bethan; Sainz-Fuertes, Ricardo; Papanastasiou, Evangelos; Di Forti, Marta; Nicholson, Tim; Vincent, Angela; Murray, Robin M

2018-06-01

There has been much recent excitement about the possibility that some cases of psychosis may be wholly due to brain-reactive antibodies, with antibodies to N-methyl-D-aspartate receptor (NMDAR) and the voltage-gated potassium channel (VGKC)-complex reported in a few patients with first-episode psychosis (FEP). Participants were recruited from psychiatric services in South London, UK, from 2009 to 2011 as part of the Genetics and Psychosis study. We conducted a case-control study to examine NMDAR and VGKC-complex antibody levels and rates of antibody positivity in 96 patients presenting with FEP and 98 controls matched for age and sex. Leucine-rich glioma inactiviated-1 (LGI1) and contactin-associated protein (CASPR) antibodies were also measured. Notably, patients with suspicion of organic disease were excluded. VGKC-complex antibodies were found in both cases (n = 3) and controls (n = 2). NMDAR antibody positivity was seen in one case and one control. Either LGI1-Abs or CASPR2-Abs were found in three cases and three controls. Neuronal antibody staining, consistent with the above results or indicating potential novel antigens, was overall positive in four patients but also in six controls. Overall, antibody positivity was at low levels only and not higher in cases than in controls. This case-control study of the prevalence of antibodies in FEP does not provide evidence to support the hypothesis that FEP is associated with an immune-mediated process in a subgroup of patients. Nevertheless, as other bio-clinical factors may influence the effect of such antibodies in a given individual, and patients with organic neurological disease may be misdiagnosed as FEP, the field requires more research to put these findings in context.

Spatial processes decouple management from objectives in a heterogeneous landscape: predator control as a case study.

PubMed

Mahoney, Peter J; Young, Julie K; Hersey, Kent R; Larsen, Randy T; McMillan, Brock R; Stoner, David C

2018-04-01

Predator control is often implemented with the intent of disrupting top-down regulation in sensitive prey populations. However, ambiguity surrounding the efficacy of predator management, as well as the strength of top-down effects of predators in general, is often exacerbated by the spatially implicit analytical approaches used in assessing data with explicit spatial structure. Here, we highlight the importance of considering spatial context in the case of a predator control study in south-central Utah. We assessed the spatial match between aerial removal risk in coyotes (Canis latrans) and mule deer (Odocoileus hemionus) resource selection during parturition using a spatially explicit, multi-level Bayesian model. With our model, we were able to evaluate spatial congruence between management action (i.e., coyote removal) and objective (i.e., parturient deer site selection) at two distinct scales: the level of the management unit and the individual coyote removal. In the case of the former, our results indicated substantial spatial heterogeneity in expected congruence between removal risk and parturient deer site selection across large areas, and is a reflection of logistical constraints acting on the management strategy and differences in space use between the two species. At the level of the individual removal, we demonstrated that the potential management benefits of a removed coyote were highly variable across all individuals removed and in many cases, spatially distinct from parturient deer resource selection. Our methods and results provide a means of evaluating where we might anticipate an impact of predator control, while emphasizing the need to weight individual removals based on spatial proximity to management objectives in any assessment of large-scale predator control. Although we highlight the importance of spatial context in assessments of predator control strategy, we believe our methods are readily generalizable in any management or large

[Voice disorders related to job stress in teaching: a case-control study].

PubMed

Giannini, Susana Pimentel Pinto; Latorre, Maria do Rosário Dias de Oliveira; Ferreira, Leslie Piccolotto

2012-11-01

This case-control study aimed to test the association between voice disorders and job stress among public schoolteachers in São Paulo, Brazil. The groups consisted of teachers with (n = 165) and without (n = 105) voice-related complaints. Both groups answered the questionnaires Conditions of Vocal Production and Job Stress Scale. Analysis of cases and controls showed comparable samples, differing only by vocal symptoms. There was a statistically significant difference between cases and controls in relation to job stress involving high strain (OR = 2.1; 95%CI: 1.1-3.9), which places high demands combined with low job control. High strain in cases in this study represents the highest risk of physical and mental disorders for teachers. Loss of voice prevents teachers from continuing in their professional role, eliminates their professional identity, and jeopardizes their career.

Misclassification of Case-Control Studies in Neurosurgery and Proposed Solutions.

PubMed

Esene, Ignatius Ngene; Mbuagbaw, Lawrence; Dechambenoit, Gilbert; Reda, Wael; Kalangu, Kazadi K

2018-04-01

Case-control studies (CCS) and cohort studies (CS) are common research designs in neurosurgery. But the term case-control study is frequently misused in the neurosurgical literature, with many articles reported as CCS, even although their methodology does not respect the basic components of a CCS. We sought to estimate the extent of these discrepancies in neurosurgical literature, explore factors contributing to mislabeling, and shed some light on study design reporting. We identified 31 top-ranking pure neurosurgical journals and searched them for articles reported as CCS, either in the title or in the abstract. The articles were read to determine if they really were CCS according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Article assessment was conducted in duplicate (agreement [κ statistics] = 99.82%). Two hundred and twenty-four articles met our inclusion criteria, 133 of which (59.38%) correctly labeled the case-control design, whereas 91 (40.62%) misclassified this study design. Cohort studies (CS) were the most common design mislabeled as case-control studies in 76 articles (33.93%), 57 of which (25.45%) were retrospective CS. The mislabeling of CCS impairs the appropriate indexing, classification, and sorting of evidence. Mislabeling CS for CCS leads to a downgrading of evidence as CS represent the highest level of evidence for observational studies. Odds ratios instead of relative risk are reported for these studies, resulting in a distortion of the measurement of the effect size, compounded when these are summarized in systematic reviews and pooled in meta-analyses. Many studies reported as CCS are not true CCS. Reporting guidelines should include items that ensure that studies are labeled correctly. STROBE guidelines should be implemented in assessment of observational studies. Researchers in neurosurgery need better training in research methods and terminology. We also recommend accrued vigilance from

Lung Cancer Risk Among Hairdressers: A Pooled Analysis of Case-Control Studies Conducted Between 1985 and 2010

PubMed Central

Olsson, Ann C.; Xu, Yiwen; Schüz, Joachim; Vlaanderen, Jelle; Kromhout, Hans; Vermeulen, Roel; Peters, Susan; Stücker, Isabelle; Guida, Florence; Brüske, Irene; Wichmann, Heinz-Erich; Consonni, Dario; Landi, Maria Teresa; Caporaso, Neil; Tse, Lap Ah; Yu, Ignatius Tak-sun; Siemiatycki, Jack; Richardson, Lesley; Mirabelli, Dario; Richiardi, Lorenzo; Simonato, Lorenzo; Gustavsson, Per; Plato, Nils; Jöckel, Karl-Heinz; Ahrens, Wolfgang; Pohlabeln, Hermann; Tardón, Adonina; Zaridze, David; Marcus, Michael W.; ‘t Mannetje, Andrea; Pearce, Neil; McLaughlin, John; Demers, Paul; Szeszenia-Dabrowska, Neonila; Lissowska, Jolanta; Rudnai, Peter; Fabianova, Eleonora; Dumitru, Rodica Stanescu; Bencko, Vladimir; Foretova, Lenka; Janout, Vladimir; Boffetta, Paolo; Fortes, Cristina; Bueno-de-Mesquita, Bas; Kendzia, Benjamin; Behrens, Thomas; Pesch, Beate; Brüning, Thomas; Straif, Kurt

2013-01-01

Increased lung cancer risks among hairdressers were observed in large registry-based cohort studies from Scandinavia, but these studies could not adjust for smoking. Our objective was to evaluate the lung cancer risk among hairdressers while adjusting for smoking and other confounders in a pooled database of 16 case-control studies conducted in Europe, Canada, China, and New Zealand between 1985 and 2010 (the Pooled Analysis of Case-Control Studies on the Joint Effects of Occupational Carcinogens in the Development of Lung Cancer). Lifetime occupational and smoking information was collected through interviews with 19,369 cases of lung cancer and 23,674 matched population or hospital controls. Overall, 170 cases and 167 controls had ever worked as hairdresser or barber. The odds ratios for lung cancer in women were 1.65 (95% confidence interval (CI): 1.16, 2.35) without adjustment for smoking and 1.12 (95% CI: 0.75, 1.68) with adjustment for smoking; however, women employed before 1954 also experienced an increased lung cancer risk after adjustment for smoking (odds ratio = 2.66, 95% CI: 1.09, 6.47). The odds ratios in male hairdressers/barbers were generally not elevated, except for an increased odds ratio for adenocarcinoma in long-term barbers (odds ratio = 2.20, 95% CI: 1.02, 4.77). Our results suggest that the increased lung cancer risks among hairdressers are due to their smoking behavior; single elevated risk estimates should be interpreted with caution and need replication in other studies. PMID:24068200

Risk factors for testicular cancer: a case-control study in twins.

PubMed

Swerdlow, A J; De Stavola, B L; Swanwick, M A; Mangtani, P; Maconochie, N E

1999-06-01

Early life and anthropometric risk factors for testicular cancer were examined in a case-control study in England and Wales in which affected male twins were compared with their unaffected male co-twins. Questionnaire data was obtained for 60 twin pairs. Significantly raised risk of testicular cancer occurred in twins who had longer arms and legs than their co-twin. There was a significant excess of testicular cancer reported in non-twin brothers, as well as in twin brothers, of cases. Risk was also significantly raised in relation to cryptorchidism. The results on limb length suggest that factors, perhaps nutritional, affecting growth before puberty, may be causes of testicular cancer. The results on risk in brothers add to evidence of a large genetic component in aetiology of the tumour. The risk associated with cryptorchidism in the twins accords with the hypothesis that cryptorchidism is causally associated with testicular cancer because it is a cause of the malignancy, rather than because the same maternal factors experienced in utero cause both conditions.

[Relations between extraction of wisdom teeth and temporomandibular disorders: a case/control study].

PubMed

Duval, Florian; Leroux, Agathe; Bertaud, Valérie; Meary, Fleur; Le Padellec, Clément; Refuveille, Laura; Lemaire, Arnaud; Sorel, Olivier; Chauvel-Lebret, Dominique

2015-09-01

The aim of this study was to assess the impact of extraction of third molars on the occurrence of temporo-mandibular disorders (TMD). A review of the literature and a case-control study have been conducted. The case-control study compares the frequency of extraction of third molars between the sample with TMD (case) and the sample without TMD (control). The proportion of patients who had undergone extractions of wisdom teeth was higher in the case group than in the control group. The difference was statistically significant when patients had undergone extraction of all four wisdom teeth or when the extraction of four wisdom teeth underwent in one sitting or under general anesthesia. The study of patients in case sample shows that all signs of TMD were more common in patients who had undergone extractions in several sessions and under local anesthesia. The temporomandibular joint sounds are significantly more frequent with local anesthesia. In the case group, 85 to 92% of patients have parafunctions and 5 to 11% have malocclusion. This demonstrates the multifactorial etiology of temporomandibular disorders. © EDP Sciences, SFODF, 2015.

Psychosocial factors in childhood pedestrian injury: a matched case-control study. Kid's'n'Cars Team.

PubMed

Christoffel, K K; Donovan, M; Schofer, J; Wills, K; Lavigne, J V

1996-01-01

Psychosocial factors--such as hyperactivity and low family cohesion--contribute to the risk for child pedestrian injury (PI), even after controlling for known demographic risk factors. Urban PI victims aged 5 to 12 years were recruited from one large, urban pediatric trauma center in a large city. One hundred twenty-eight cases were matched to uninjured children on age, sex, race, location of residence, and parental education. Among matched cases: 70% were male, 41% were black, 33% were Hispanic, and 66% of the mothers had a high school education or less. RESEARCH DESIGN AND MEASUREMENTS: Case-control comparisons on 19 psychosocial variables drawn from interviews and standardized tests, using one-tailed matched-pairs t tests and conditional logistic regression analyses. Cases had higher reported physical quotient [PQ] (P = .01), self-help quotient (P = .04), and family stress (P = .02), and lower family supportiveness (P = .03). Multivariate analyses confirmed that PQ was higher in cases (10-point increase: odds ratio (OR) = 1.32 [90% confidence interval (CI) 1.01-1.76], that stress was higher in cases (1 log increase: OR 2.13, [1.26-3.61]), and that cases had lower family supportiveness (25-point decrease: OR 1.43 [1.25-1.63]). It also identified household crowding as a factor for non-black cases (OR for increase of 0.25 people per room: 2.18, [1.31-3.62]). Even when controlling for demographic risk, several family factors and one child factor place children at risk for PI. Clinicians may choose to use these as indicators for injury prevention counseling. Research on family effects may help clarify means to protect children who are demographically at risk for PI.

Exposure to pistachio pesticides and stillbirth: a case-control study.

PubMed

Razi, Saeid; Rezaeian, Mohsen; Dehkordi, Fatemeh Ghani; Manshoori, Azita; Goujani, Reza; Vazirinejad, Reza

2016-01-01

Stillbirth is an undesirable outcome of pregnancy. In light of the increasing use of pesticides and growing concerns about the possible health effects of agricultural pesticides, we investigated the effect of exposure to pistachio pesticides on stillbirth in pregnant mothers. This case-control study was conducted in Rafsanjan, Iran from 2011 to 2012. A total of 125 females who had a recent stillbirth were included as the case group, and 250 controls were selected from females who had a recent live birth. For each case, two controls with the nearest propensity score to the case were selected. Data were collected using a protocol developed by the researcher that involved interviewing respondents and reviewing their medical records. Conditional multivariate and univariate logistic regression analysis were performed and odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. The ORs of stillbirth in mothers living in pistachio gardens and those who were exposed to sprayed pesticides, in comparison to the controls, were 14.1 (95% CI, 3.3 to 63.4) and 5.0 (95% CI, 1.2 to 28.6), respectively. No significant differences were found in stillbirth rates according to the distance between the mother's residence and a pistachio garden or involvement in agricultural activities. The results of our study showed that exposure to pistachio pesticides during pregnancy may increase the likelihood of stillbirth in mothers.

Childhood leukaemia and distance from power lines in California: a population-based case-control study.

PubMed

Crespi, Catherine M; Vergara, Ximena P; Hooper, Chris; Oksuzyan, Sona; Wu, Sheng; Cockburn, Myles; Kheifets, Leeka

2016-06-28

Studies have reported an increased risk of childhood leukaemia associated with living near high-voltage electric power transmission lines that extend to distances at which magnetic fields from lines are negligible. We conducted a large records-based case-control study of childhood leukaemia risk in the population living near power lines in California. The study included 5788 childhood leukaemia and 3308 central nervous system (CNS) cancer cases (for comparison) born in and diagnosed in California (1986-2008), and matched to population-based controls by age and sex. We geocoded birth address and estimated the distance from residence to transmission lines using geographic information systems, aerial imagery, and, for some residences, site visits. For leukaemia, there was a slight excess of cases within 50 m of a transmission line over 200 kV (odds ratio 1.4, 95% confidence interval 0.7-2.7). There was no evidence of increased risk for distances beyond 50 m, for lower-voltage lines, or for CNS cancers. Our findings did not clearly support an increased childhood leukaemia risk associated with close proximity (<50 m) to higher voltage lines, but could be consistent with a small increased risk. Reports of increased risk for distances beyond 50 m were not replicated.

Reusable experiment controllers, case studies

NASA Astrophysics Data System (ADS)

Buckley, Brian A.; Gaasbeck, Jim Van

1996-03-01

Congress has given NASA and the science community a reality check. The tight and ever shrinking budgets are trimming the fat from many space science programs. No longer can a Principal Investigator (PI) afford to waste development dollars on re-inventing spacecraft controllers, experiment/payload controllers, ground control systems, or test sets. Inheritance of the Ground Support Equipment (GSE) from one program to another is not a significant re-use of technology to develop a science mission in these times. Reduction of operational staff and highly autonomous experiments are needed to reduce the sustaining cost of a mission. The re-use of an infrastructure from one program to another is needed to truly attain the cost and time savings required. Interface and Control Systems, Inc. (ICS) has a long history of re-usable software. Navy, Air Force, and NASA programs have benefited from the re-use of a common control system from program to program. Several standardization efforts in the AIAA have adopted the Spacecraft Command Language (SCL) architecture as a point solution to satisfy requirements for re-use and autonomy. The Environmental Research Institute of Michigan (ERIM) has been a long-standing customer of ICS and are working on their 4th generation system using SCL. Much of the hardware and software infrastructure has been re-used from mission to mission with little cost for re-hosting a new experiment. The same software infrastructure has successfully been used on Clementine, and an end-to-end system is being deployed for the Far Ultraviolet Spectroscopic Explorer (FUSE) for Johns Hopkins University. A case study of the ERIM programs, Clementine and FUSE will be detailed in this paper.

Risk factors for measles among adults in Tianjin, China: Who should be controls in a case-control study?

PubMed

Wagner, Abram L; Boulton, Matthew L; Gillespie, Brenda W; Zhang, Ying; Ding, Yaxing; Carlson, Bradley F; Luo, Xiaoyan; Montgomery, JoLynn P; Wang, Xiexiu

2017-01-01

Control groups in previous case-control studies of vaccine-preventable diseases have included people immune to disease. This study examines risk factors for measles acquisition among adults 20 to 49 years of age in Tianjin, China, and compares findings using measles IgG antibody-negative controls to all controls, both IgG-negative and IgG-positive. Measles cases were sampled from a disease registry, and controls were enrolled from community registries in Tianjin, China, 2011-2015. Through a best subsets selection procedure, we compared which variables were selected at different model sizes when using IgG-negative controls or all controls. We entered risk factors for measles in two separate logistic regression models: one with measles IgG-negative controls and the other with all controls. The study included 384 measles cases and 1,596 community controls (194 IgG-negative). Visiting a hospital was an important risk factor. For specialty hospitals, the odds ratio (OR) was 4.53 (95% confidence interval (CI): 1.28, 16.03) using IgG-negative controls, and OR = 5.27 (95% CI: 2.73, 10.18) using all controls. Variables, such as age or length of time in Tianjin, were differentially selected depending on the control group. Individuals living in Tianjin ≤3 years had 2.87 (95% CI: 1.46, 5.66) times greater odds of measles case status compared to all controls, but this relationship was not apparent for IgG-negative controls. We recommend that case-control studies examining risk factors for infectious diseases, particularly in the context of transmission dynamics, consider antibody-negative controls as the gold standard.

Cerebral malaria and sequelar epilepsy: first matched case-control study in Gabon.

PubMed

Ngoungou, Edgard Brice; Koko, Jean; Druet-Cabanac, Michel; Assengone-Zeh-Nguema, Yvonne; Launay, Marylène Ndong; Engohang, Edouard; Moubeka-Mounguengui, Martine; Kouna-Ndouongo, Philomène; Loembe, Paul-Marie; Preux, Pierre-Marie; Kombila, Maryvonne

2006-12-01

Cerebral malaria (CM) is suspected to be a potential cause of epilepsy in tropical areas. The purpose of this article was to evaluate the relationship between CM and epilepsy in Gabon. A matched case-control study was carried out on a sample of subjects aged six months to 25 years and hospitalized between 1990 and 2004 in three hospitals in Libreville, Gabon. Cases were defined as patients suffering from epilepsy and confirmed by a neurologist. Controls were defined as patients without epilepsy. The exposure of interest was CM according to WHO criteria. In total, 296 cases and 296 controls were included. Of these, 36 (26 cases and 10 controls) had a CM history. The adjusted odds ratio (aOR) to develop epilepsy after CM was 3.9 [95% CI: 1.7-8.9], p<0.001. Additional risk factors were identified: family history of epilepsy: aOR=6.0 [95% CI: 2.6-14.1], p<0.0001, and febrile convulsions: aOR=9.2 [95% CI 4.0-21.1], p<0.0001. This first case-control study on that issue suggests that epilepsy-related CM is an underrecognized problem. It emphasizes the need for further studies to better evaluate the role of convulsions during CM.

A Data Management System for Multi-Phase Case-Control Studies

PubMed Central

Gibeau, Joanne M.; Steinfeldt, Lois C.; Stine, Mark J.; Tullis, Katherine V.; Lynch, H. Keith

1983-01-01

The design of a computerized system for the management of data in multi-phase epidemiologic case-control studies is described. Typical study phases include case-control selection, abstracting of data from medical records, and interview of study subjects or next of kin. In consultation with project personnel, requirements for the system were established: integration of data from all study phases into one data base, accurate follow-up of subjects through the study, sophisticated data editing capabilities, ready accessibility of specified programs to project personnel, and generation of current status and exception reports for project managment. SIR (Scientific Information Retrieval), a commercially available data base management system, was selected as the foundation of this system. The system forms a comprehensive data management system applicable to many types of public health research studies.

[Application of nested case-control study on safe evaluation of post-marketing traditional Chinese medicine injection].

PubMed

Xiao, Ying; Zhao, Yubin; Xie, Yanming

2011-10-01

The nested case-control study design (or the case-control in a cohort study) is described here as a new study design used in safe evaluation of post-marketing traditional Chinese medicine injection. In the nested case-control study, cases of a disease that occur in a defined cohort are identified and, for each, a specified number of matched controls is selected from among those in the cohort who have not developed the disease by the time of disease occurrence in the case. For many research questions, the nested case-control design potentially offers impressive reductions in costs and efforts of data collection and analysis compared with the full cohort approach, with relatively minor loss in statistical efficiency. The nested case-control design is particularly advantageous for studies in safe evaluation of post-marketing traditional Chinese medicine injection. Some examples of the application of nested case-control study were given.

Leptospira Exposure and Gardeners: A Case-Control Seroprevalence Study

PubMed Central

Alvarado-Esquivel, Cosme; Hernandez-Tinoco, Jesus; Sanchez-Anguiano, Luis Francisco; Ramos-Nevarez, Agar; Cerrillo-Soto, Sandra Margarita; Guido-Arreola, Carlos Alberto

2016-01-01

Background Leptospira can be found in soil. However, it is unclear whether occupational exposure to soil may represent a risk for Leptospira infection in humans. Therefore, we sought to determine the association of Leptospira IgG seroprevalence with the occupation of gardener, and to determine the epidemiological characteristics of gardeners associated with Leptospira exposure. Methods We performed a case-control study in 168 gardeners and 168 age- and gender-matched control subjects without gardening occupation in Durango City, Mexico. The seroprevalence of anti-Leptospira IgG antibodies in cases and controls was determined using an enzyme immunoassay. Bivariate and multivariate analyses were used to assess the association of Leptospira exposure and the characteristics of the gardeners. Results Anti-Leptospira IgG antibodies were found in 10 (6%) of 168 gardeners and in 15 (8.9%) of 168 control subjects (odds ratio (OR): 0.64; 95% confidence interval (CI): 0.28 - 1.48; P = 0.40). Multivariate analysis showed that Leptospira seropositivity was positively associated with female gender (OR: 5.82; 95% CI: 1.11 - 30.46; P = 0.03), and negatively associated with eating while working (OR: 0.21; 95% CI: 0.05 - 0.87; P = 0.03). In addition, multivariate analysis showed that high anti-Leptospira levels were associated with consumption of boar meat (OR: 28.00; 95% CI: 1.20 - 648.80; P = 0.03). Conclusions This is the first case-control study of Leptospira exposure in gardeners. Results do not support an association of Leptospira exposure with the occupation of gardener. However, further studies to confirm the lack of this association are needed. The potential role of consumption of boar meat in Leptospira infection deserves further investigation. PMID:26668679

The lack of selection bias in a snowball sampled case-control study on drug abuse.

PubMed

Lopes, C S; Rodrigues, L C; Sichieri, R

1996-12-01

Friend controls in matched case-control studies can be a potential source of bias based on the assumption that friends are more likely to share exposure factors. This study evaluates the role of selection bias in a case-control study that used the snowball sampling method based on friendship for the selection of cases and controls. The cases selected fro the study were drug abusers located in the community. Exposure was defined by the presence of at least one psychiatric diagnosis. Psychiatric and drug abuse/dependence diagnoses were made according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Cases and controls were matched on sex, age and friendship. The measurement of selection bias was made through the comparison of the proportion of exposed controls selected by exposed cases (p1) with the proportion of exposed controls selected by unexposed cases (p2). If p1 = p2 then, selection bias should not occur. The observed distribution of the 185 matched pairs having at least one psychiatric disorder showed a p1 value of 0.52 and a p2 value of 0.51, indicating no selection bias in this study. Our findings support the idea that the use of friend controls can produce a valid basis for a case-control study.

Higher sweat chloride levels in patients with asthma: a case-control study.

PubMed

Awasthi, Shally; Dixit, Pratibha; Maurya, Nutan

2015-02-01

To screen asthmatic patients by sweat chloride test to identify proportion with Cystic Fibrosis (CF); (Sweat chloride level >60 mmol/L). Also, to compare sweat chloride levels between cases of bronchial asthma and age and sex matched healthy children aged 5 mo-15 y. The present case-control study was conducted in a tertiary care hospital in India. Cases of bronchial asthma, diagnosed by GINA guideline 2008, and age matched healthy controls were included. Case to control ratio was 2:1. Sweat Chloride test was done by Pilocarpine Iontophoresis method. From April 2010 through May 2012, 216 asthmatics and 112 controls were recruited. Among asthmatics, there was no case of Cystic Fibrosis. Mean sweat chloride levels in asthmatics was 22.39 ± 8.45 mmol/L (inter-quartile range - 15-28 mmol/L) and in controls 19.55 ± 7.04 mmol/L (inter-quartile range - 15-23.5 mmol/L) (p value = 0.048). No Cystic Fibrosis case was identified among asthmatics. Mean sweat chloride levels were higher in asthmatics as compared to controls.

Association between diabetes and tuberculosis: case-control study.

PubMed

Pereira, Susan Martins; Araújo, Gleide Santos de; Santos, Carlos Antônio de Souza Teles; Oliveira, Maeli Gomes de; Barreto, Maurício Lima

2016-12-22

To test the association between diabetes and tuberculosis. It is a case-control study, matched by age and sex. We included 323 new cases of tuberculosis with positive results for bacilloscopy. The controls were 323 respiratory symptomatic patients with negative bacilloscopy, from the same health services, such as: ambulatory cases from three referral hospitals and six basic health units responsible for the notifications of new cases of tuberculosis in Salvador, Bahia. Data collection occurred between 2008 and 2010. The instruments used were structured interview, including clinical data, capillary blood glucose (during fasting or postprandial), and the CAGE questionnaire for screening of abusive consumption of alcohol. Descriptive, exploratory, and multivariate analysis was performed using conditional logistic regression. The average age of the cases was 38.5 (SD = 14.2) years and of the controls, 38.5 (SD = 14.3) years. Among cases and controls, most subjects (61%) were male. In univariate analysis we found association between the occurrence of diabetes and tuberculosis (OR = 2.37; 95%CI 1.04-5.42), which remained statistically significant after adjustment for potential confounders (OR = 3.12; 95%CI 1.12-7.94). The association between diabetes and tuberculosis can hinder the control of tuberculosis, contributing to the maintainance of the disease burden. The situation demands increasing early detection of diabetes among people with tuberculosis, in an attempt to improve disease control strategies. Testar a associação entre diabetes e tuberculose. Trata-se de estudo caso-controle, pareado por idade e sexo. Foram incluídos 323 casos novos de tuberculose com resultados positivos à baciloscopia. Os controles foram 323 sintomáticos respiratórios com baciloscopia negativa, oriundos dos mesmos serviços de saúde dos casos: ambulatórios de três hospitais de referência e seis unidades básicas de saúde responsáveis pelas notificações dos casos novos de

Homocysteine and Coronary Heart Disease: Meta-analysis of MTHFR Case-Control Studies, Avoiding Publication Bias

PubMed Central

Verhoef, Petra; Dötsch-Klerk, Mariska; Lathrop, Mark; Xu, Peng; Nordestgaard, Børge G.; Holm, Hilma; Hopewell, Jemma C.; Saleheen, Danish; Tanaka, Toshihiro; Anand, Sonia S.; Chambers, John C.; Kleber, Marcus E.; Ouwehand, Willem H.; Yamada, Yoshiji; Elbers, Clara; Peters, Bas; Stewart, Alexandre F. R.; Reilly, Muredach M.; Thorand, Barbara; Yusuf, Salim; Engert, James C.; Assimes, Themistocles L.; Kooner, Jaspal; Danesh, John; Watkins, Hugh; Samani, Nilesh J.

2012-01-01

Background Moderately elevated blood levels of homocysteine are weakly correlated with coronary heart disease (CHD) risk, but causality remains uncertain. When folate levels are low, the TT genotype of the common C677T polymorphism (rs1801133) of the methylene tetrahydrofolate reductase gene (MTHFR) appreciably increases homocysteine levels, so “Mendelian randomization” studies using this variant as an instrumental variable could help test causality. Methods and Findings Nineteen unpublished datasets were obtained (total 48,175 CHD cases and 67,961 controls) in which multiple genetic variants had been measured, including MTHFR C677T. These datasets did not include measurements of blood homocysteine, but homocysteine levels would be expected to be about 20% higher with TT than with CC genotype in the populations studied. In meta-analyses of these unpublished datasets, the case-control CHD odds ratio (OR) and 95% CI comparing TT versus CC homozygotes was 1.02 (0.98–1.07; p = 0.28) overall, and 1.01 (0.95–1.07) in unsupplemented low-folate populations. By contrast, in a slightly updated meta-analysis of the 86 published studies (28,617 CHD cases and 41,857 controls), the OR was 1.15 (1.09–1.21), significantly discrepant (p = 0.001) with the OR in the unpublished datasets. Within the meta-analysis of published studies, the OR was 1.12 (1.04–1.21) in the 14 larger studies (those with variance of log OR<0.05; total 13,119 cases) and 1.18 (1.09–1.28) in the 72 smaller ones (total 15,498 cases). Conclusions The CI for the overall result from large unpublished datasets shows lifelong moderate homocysteine elevation has little or no effect on CHD. The discrepant overall result from previously published studies reflects publication bias or methodological problems. Please see later in the article for the Editors' Summary PMID:22363213

Pretreatment serum concentrations of 25-hydroxyvitamin D and breast cancer prognostic characteristics: a case-control and a case-series study.

PubMed

Yao, Song; Sucheston, Lara E; Millen, Amy E; Johnson, Candace S; Trump, Donald L; Nesline, Mary K; Davis, Warren; Hong, Chi-Chen; McCann, Susan E; Hwang, Helena; Kulkarni, Swati; Edge, Stephen B; O'Connor, Tracey L; Ambrosone, Christine B

2011-02-28

Results from epidemiologic studies on the relationship between vitamin D and breast cancer risk are inconclusive. It is possible that vitamin D may be effective in reducing risk only of specific subtypes due to disease heterogeneity. In case-control and case-series analyses, we examined serum concentrations of 25-hydroxyvitamin D (25OHD) in relation to breast cancer prognostic characteristics, including histologic grade, estrogen receptor (ER), and molecular subtypes defined by ER, progesterone receptor (PR) and HER2, among 579 women with incident breast cancer and 574 controls matched on age and time of blood draw enrolled in the Roswell Park Cancer Institute from 2003 to 2008. We found that breast cancer cases had significantly lower 25OHD concentrations than controls (adjusted mean, 22.8 versus 26.2 ng/mL, p<0.001). Among premenopausal women, 25OHD concentrations were lower in those with high- versus low-grade tumors, and ER negative versus ER positive tumors (p≤0.03). Levels were lowest among women with triple-negative cancer (17.5 ng/mL), significantly different from those with luminal A cancer (24.5 ng/mL, p = 0.002). In case-control analyses, premenopausal women with 25OHD concentrations above the median had significantly lower odds of having triple-negative cancer (OR = 0.21, 95% CI = 0.08-0.53) than those with levels below the median; and every 10 ng/mL increase in serum 25OHD concentrations was associated with a 64% lower odds of having triple-negative cancer (OR = 0.36, 95% CI = 0.22-0.56). The differential associations by tumor subtypes among premenopausal women were confirmed in case-series analyses. In our analyses, higher serum levels of 25OHD were associated with reduced risk of breast cancer, with associations strongest for high grade, ER negative or triple negative cancers in premenopausal women. With further confirmation in large prospective studies, these findings could warrant vitamin D supplementation for reducing breast

A case-control study: occupational cooking and the risk of uveal melanoma

PubMed Central

2010-01-01

Background A European-wide population based case-control study (European rare cancer study) undertaken in nine European countries examined risk factors for uveal melanoma. They found a positive association between cooks and the risk of uveal melanoma. In our study we examine whether cooks or people who worked in cook related jobs have an increased uveal melanoma risk. Methods We conducted a case-control study during 2002 and 2005. Overall, 1653 eligible subjects (age range: 20-74 years, living in Germany) participated. Interviews were conducted with 459 incident uveal melanoma cases, 827 population controls, 180 ophthalmologist controls and 187 sibling controls. Data on occupational exposure were obtained from a self-administered postal questionnaire and a computer-assisted telephone interview. We used conditional logistic regression to estimate odds ratios adjusting for the matching factors. Results Overall, we did not observe an increased risk of uveal melanoma among people who worked as cooks or who worked in cook related jobs. When we restricted the source population of our study to the population of the Federal State of Northrhine-Westphalia, we observed an increased risk among subjects who were categorized as cooks in the cases-control analysis. Conclusion Our results are in conflict with former results of the European rare cancer study. Considering the rarity of the disease laboratory in vitro studies of human uveal melanoma cell lines should be done to analyze potential exposure risk factors like radiation from microwaves, strong light from incandescent ovens, or infrared radiation. PMID:20969762

Maternal sepsis: a Scottish population-based case-control study.

PubMed

Acosta, C D; Bhattacharya, S; Tuffnell, D; Kurinczuk, J J; Knight, M

2012-03-01

To describe the risk of maternal sepsis associated with obesity and other understudied risk factors such as operative vaginal delivery. Population-based, case-control study. North NHS region of Scotland. All cases of pregnant, intrapartum and postpartum women with International Classification of Disease-9 codes for sepsis or severe sepsis recorded in the Aberdeen Maternal and Neonatal Databank (AMND) from 1986 to 2009. Four controls per case selected from the AMND were frequency matched on year-of-delivery. Cases and controls were compared; significant variables from univariable regression were adjusted in a multivariable logistic regression model. Dependent variables were uncomplicated sepsis or severe ('near-miss') sepsis. Independent variables were demographic, medical and clinical delivery characteristics. Unadjusted and adjusted odds ratios (OR) with 95% confidence intervals (95% CI) are reported. Controlling for mode of delivery and demographic and clinical factors, obese women had twice the odds of uncomplicated sepsis (OR 2.12; 95% CI 1.14-3.89) compared with women of normal weight. Age <25 years (OR 5.15; 95% CI 2.43-10.90) and operative vaginal delivery (OR 2.20; 95% CI 1.02-4.87) were also significant predictors of sepsis. Known risk factors for maternal sepsis were also significant in this study (OR for uncomplicated and severe sepsis respectively): multiparity (OR 6.29, 12.04), anaemia (OR 3.43, 18.49), labour induction (OR 3.92 severe only), caesarean section (OR 3.23, 13.35), and preterm birth (OR 2.46 uncomplicated only). Obesity, operative vaginal delivery and age <25 years are significant risk factors for sepsis and should be considered in clinical obstetric care. © 2012 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2012 RCOG.

Use of Organic Nitrates and the Risk of Hip Fracture: A Population-Based Case-Control Study

PubMed Central

Pouwels, Sander; Lalmohamed, Arief; van Staa, Tjeerd; Cooper, Cyrus; Souverein, Patrick; Leufkens, Hubertus G.; Rejnmark, Lars; de Boer, Anthonius; Vestergaard, Peter; de Vries, Frank

2010-01-01

Context: Use of organic nitrates has been associated with increased bone mineral density. Moreover, a large Danish case-control study reported a decreased fracture risk. However, the association with duration of nitrate use, dose frequency, and impact of discontinuation has not been extensively studied. Objective: Our objective was to evaluate the association between organic nitrates and hip fracture risk. Methods: A case-control study was conducted using the Dutch PHARMO Record Linkage System (1991–2002, n = 6,763 hip fracture cases and 26,341 controls). Cases had their first admission for hip fracture, whereas controls had not sustained any fracture after enrollment. Current users of organic nitrates were patients who had received a prescription within 90 d before the index date. The analyses were adjusted for disease and drug history. Results: Current use of nitrates was not associated with a decreased risk of hip fracture [adjusted odds ratio (OR) = 0.93; 95% confidence interval (CI) = 0.83–1.04]. Those who used as-needed medication only had a lower risk of hip fracture (adjusted OR = 0.83; 95% CI = 0.63–1.08) compared with users of maintenance medication only (adjusted OR = 1.17; 95% CI = 0.97–1.40). No association was found between duration of nitrate use and fracture risk. Conclusions: Our overall analyses showed that risk of a hip fracture was significantly lower among users of as-needed organic nitrates, when compared with users of maintenance medication. Our analyses of hip fracture risks with duration of use did not further support a beneficial effect of organic nitrates on hip fracture, although residual confounding may have masked beneficial effects. PMID:20130070

Use of organic nitrates and the risk of hip fracture: a population-based case-control study.

PubMed

Pouwels, Sander; Lalmohamed, Arief; van Staa, Tjeerd; Cooper, Cyrus; Souverein, Patrick; Leufkens, Hubertus G; Rejnmark, Lars; de Boer, Anthonius; Vestergaard, Peter; de Vries, Frank

2010-04-01

Use of organic nitrates has been associated with increased bone mineral density. Moreover, a large Danish case-control study reported a decreased fracture risk. However, the association with duration of nitrate use, dose frequency, and impact of discontinuation has not been extensively studied. Our objective was to evaluate the association between organic nitrates and hip fracture risk. A case-control study was conducted using the Dutch PHARMO Record Linkage System (1991-2002, n = 6,763 hip fracture cases and 26,341 controls). Cases had their first admission for hip fracture, whereas controls had not sustained any fracture after enrollment. Current users of organic nitrates were patients who had received a prescription within 90 d before the index date. The analyses were adjusted for disease and drug history. Current use of nitrates was not associated with a decreased risk of hip fracture [adjusted odds ratio (OR) = 0.93; 95% confidence interval (CI) = 0.83-1.04]. Those who used as-needed medication only had a lower risk of hip fracture (adjusted OR = 0.83; 95% CI = 0.63-1.08) compared with users of maintenance medication only (adjusted OR = 1.17; 95% CI = 0.97-1.40). No association was found between duration of nitrate use and fracture risk. Our overall analyses showed that risk of a hip fracture was significantly lower among users of as-needed organic nitrates, when compared with users of maintenance medication. Our analyses of hip fracture risks with duration of use did not further support a beneficial effect of organic nitrates on hip fracture, although residual confounding may have masked beneficial effects.

Validation of self-reported start year of mobile phone use in a Swedish case-control study on radiofrequency fields and acoustic neuroma risk.

PubMed

Pettersson, David; Bottai, Matteo; Mathiesen, Tiit; Prochazka, Michaela; Feychting, Maria

2015-01-01

The possible effect of radiofrequency exposure from mobile phones on tumor risk has been studied since the late 1990s. Yet, empirical information about recall of the start of mobile phone use among adult cases and controls has never been reported. Limited knowledge about recall errors hampers interpretations of the epidemiological evidence. We used network operator data to validate the self-reported start year of mobile phone use in a case-control study of mobile phone use and acoustic neuroma risk. The answers of 96 (29%) cases and 111 (22%) controls could be included in the validation. The larger proportion of cases reflects a more complete and detailed reporting of subscription history. Misclassification was substantial, with large random errors, small systematic errors, and no significant differences between cases and controls. The average difference between self-reported and operator start year was -0.62 (95% confidence interval: -1.42, 0.17) years for cases and -0.71 (-1.50, 0.07) years for controls, standard deviations were 3.92 and 4.17 years, respectively. Agreement between self-reported and operator-recorded data categorized into short, intermediate and long-term use was moderate (kappa statistic: 0.42). Should an association exist, dilution of risk estimates and distortion of exposure-response patterns for time since first mobile phone use could result from the large random errors in self-reported start year. Retrospective collection of operator data likely leads to a selection of "good reporters", with a higher proportion of cases. Thus, differential recall cannot be entirely excluded.

Healthy control subjects are poorly defined in case-control studies of irritable bowel syndrome

PubMed Central

Ghorbani, Shireen; Nejad, Amir; Law, David; Chua, Kathleen S.; Amichai, Meridythe M.; Pimentel, Mark

2015-01-01

Background Case-control studies are vital for understanding the pathophysiology of gastrointestinal disease. While the definition of disease is clear, the definition of healthy control is not. This is particularly relevant for functional bowel diseases such as irritable bowel syndrome (IBS). In this study, a systematic review formed the basis for a prospective study evaluating the effectiveness of commonly used techniques for defining healthy controls in IBS. Methods A systematic review of the literature was conducted to identify case-control studies involving functional gastrointestinal disorders. “Lack of Rome criteria”, self-description as “healthy” and the bowel disease questionnaire (BDQ) were common methods for identifying healthy controls. These 3 methods were then applied to a cohort of 53 non-patient subjects to determine their validity compared to objective outcome measures (7-day stool diary). Results “Lack of Rome criteria” and “healthy” self-description were the most common methods for identifying healthy control subjects, but many studies failed to describe the methods used. In the prospective study, more subjects were identified as non-healthy using the BDQ than using either lack of Rome criteria (P=0.01) or “healthy” self-description (P=0.026). Furthermore, stool diaries identified several subjects with abnormal stool form and/or frequency which were not identified using lack of Rome criteria or the “healthy” question. Comparisons revealed no agreement (κ) between the different methods for defining healthy controls. Conclusions The definitions of healthy controls in studies of functional bowel diseases such as IBS are inconsistent. Since functional symptoms are common, a strict definition of “normal” is needed in this area of research. PMID:25609236

Risk factors for neural tube defects in Riyadh City, Saudi Arabia: Case-control study.

PubMed

Salih, Mustafa A M; Murshid, Waleed R; Mohamed, Ashry Gad; Ignacio, Lena C; de Jesus, Julie E; Baabbad, Rubana; El Bushra, Hassan M

2014-01-01

Both genetic and non-genetic environmental factors are involved in the etiology of neural tube defects (NTD) which affect 0.5-2/1000 pregnancies worldwide. This study aimed to explore the risk factors for the development of NTD in Saudi population, and highlight identifiable and preventable causes. Similar studies are scarce in similar populations ofthe Arabian Peninsula and North Africa. This is an unmatched concurrent case-control study including NTD cases born at King Khalid University Hospital, Riyadh during a 4-year period (2002-2006). The case-control study included 25 cases and 125 controls (case: control ratio of 1:5). Years of formal education, employment, household environment (including availability of air conditioning) and rate of parental consanguinity did not differ between mothers of cases and controls. Significantly higher proportion of mothers of cases had history of stillbirth compared to control mothers (16% vs 4.1%, P=0.02). Also family history of hydrocephalus and congenital anomalies were more prevalent in cases than controls (P values=0.0000 and 0.003, respectively). There was significant protective effect of periconceptional folic acid consumption both prior to conception (OR 0.02, 95% CI 0.00-0.07) and during the first 6 weeks of conception (OR 0.13, 95% CI 0.04-0.39). Further research, including a larger cohort, is required to enable ascertainment of gene-nutrient and gene environment interactions associated with NTD in Saudi Arabia.

Simple F Test Reveals Gene-Gene Interactions in Case-Control Studies

PubMed Central

Chen, Guanjie; Yuan, Ao; Zhou, Jie; Bentley, Amy R.; Adeyemo, Adebowale; Rotimi, Charles N.

2012-01-01

Missing heritability is still a challenge for Genome Wide Association Studies (GWAS). Gene-gene interactions may partially explain this residual genetic influence and contribute broadly to complex disease. To analyze the gene-gene interactions in case-control studies of complex disease, we propose a simple, non-parametric method that utilizes the F-statistic. This approach consists of three steps. First, we examine the joint distribution of a pair of SNPs in cases and controls separately. Second, an F-test is used to evaluate the ratio of dependence in cases to that of controls. Finally, results are adjusted for multiple tests. This method was used to evaluate gene-gene interactions that are associated with risk of Type 2 Diabetes among African Americans in the Howard University Family Study. We identified 18 gene-gene interactions (P < 0.0001). Compared with the commonly-used logistical regression method, we demonstrate that the F-ratio test is an efficient approach to measuring gene-gene interactions, especially for studies with limited sample size. PMID:22837643

Spatial variation in mortality risk for haematological malignancies near a petrochemical refinery: a population-based case-control study

PubMed Central

Di Salvo, Francesca; Meneghini, Elisabetta; Vieira, Veronica; Baili, Paolo; Mariottini, Mauro; Baldini, Marco; Micheli, Andrea; Sant, Milena

2015-01-01

Introduction The study investigated the geographic variation of mortality risk for hematological malignancies (HMs) in order to identify potential high-risk areas near an Italian petrochemical refinery. Material and methods A population-based case-control study was conducted and residential histories for 171 cases and 338 sex- and age-matched controls were collected. Confounding factors were obtained from interviews with consenting relatives for 109 HM deaths and 267 controls. To produce risk mortality maps, two different approaches were applied. We mapped (1) adptive kernel density relative risk estimation (KDE) for case-control studies which estimates a spatial relative risk function using the ratio between cases and controls’ densities, and (2) estimated odds ratios for case-control study data using generalized additive models (GAMs) to smooth the effect of location, a proxy for exposure, while adjusting for confounding variables. Results No high-risk areas for HM mortality were identified among all subjects (men and women combined), by applying both approaches. Using the adaptive KDE approach, we found a significant increase in death risk only among women in a large area 2–6 km southeast of the refinery and the application of GAMs also identified a similarly-located significant high-risk area among women only (global p-value<0.025). Potential confounding risk factors we considered in the GAM did not alter the results. Conclusion Both approaches identified a high-risk area close to the refinery among women only. Those spatial methods are useful tools for public policy management to determine priority areas for intervention. Our findings suggest several directions for further research in order to identify other potential environmental exposures that may be assessed in forthcoming studies based on detailed exposure modeling. PMID:26073202

Effectiveness of reactive oral cholera vaccination in rural Haiti: a case-control study

PubMed Central

Ivers, Louise C; Hilaire, Isabelle J; Teng, Jessica E; Almazor, Charles P; Jerome, J Gregory; Ternier, Ralph; Boncy, Jacques; Buteau, Josiane; Murray, Megan B; Harris, Jason B; Franke, Molly F

2015-01-01

Background Between April and June 2012, a reactive cholera vaccination campaign was conducted in Haiti using an oral inactivated bivalent whole-cell vaccine (BivWC). Methods We conducted a case-control study to estimate field effectiveness of the vaccine. Cases had acute watery diarrhea, sought treatment at one of three participating cholera treatment units from October 24, 2012 through March 9, 2014, and had a stool sample positive for cholera by culture. For each case, four controls (individuals who did not seek treatment for acute watery diarrhea) were matched by location of residence, calendar time, and age. We also conducted a bias-indicator case-control study to assess the likelihood of bias in the vaccine effectiveness (VE) study. Findings During the study period, 114 eligible individuals presented with acute watery diarrhea and were enrolled. 47 were analyzed as cases in the VE case-control study and 42 as cases in the bias-indicator study. In multivariable analyses, VE was 63% [95% confidence interval (CI): 8%–85%] by self-reported vaccination and 58% [95% CI: 13%–80%] for verified vaccination. Neither self-reported nor verified vaccination was significantly associated with non-cholera diarrhea (VE: 18% [95% CI: −208%–−78%] by self-report and −21% [95%CI: −238%–57%] for verified vaccination). Interpretation BivWC oral cholera vaccine was effective in protecting against cholera in Haiti during the study period –from 4 through 24 months after vaccination. Vaccination is an important component of epidemic cholera control efforts. Funding National Institutes of Health, Delivering Oral Vaccines Effectively project, Department of Global Health and Social Medicine at Harvard Medical School. PMID:25701994

Spinal cord injury and women's sexual life: case-control study.

PubMed

Merghati-Khoei, E; Emami-Razavi, S H; Bakhtiyari, M; Lamyian, M; Hajmirzaei, S; Ton-Tab Haghighi, S; Korte, J E; Maasoumi, R

2017-03-01

Study design :This is a case-control study. The objective of this study was to estimate the magnitude of association between spinal cord injury (SCI) and women's quality of sexual life and sexual function. This study was conducted in the Brain and Spinal Cord Injury Research Center, Tehran University of Medical Sciences, Tehran, Iran. From the referral university-based clinics, we used simple random sampling to recruit 62 women: 31 women with SCI and 31 women without SCI. Socio-demographic and reproductive traits questionnaire, Sexual Quality of life-Female (SQOL-F), Female Sexual Function Index (FSFI) and Spinal Cord Independence Measure (SCIM) were completed using telephone and face-to-face interviews in the cases and controls. After univariate analyses, multivariate linear and proportional odds regression models were conducted to investigate the relation between SCI and women's quality of sexual life, as well as sexual function. The mean age of cases and controls was 35.42±6.51 and 33.77±4.02 years. Most women were high school-educated and housewives. Adjusting for probable confounders, the proportional odds regression model showed a significant relationship between the spinal cord injury (AOR=4.2, 95% CI: 1.8-9.2), non-college-educated (AOR=3.1, 95% CI: 1.2-5.9) and employed (AOR=1.8, 95% CI: 1.1-1.8) variables and being in one of the moderate or poor quality of life classes. Scores of SQOL-F and FSFI domains, except satisfaction, were significantly worse in cases versus controls (P<0.001). Although our participants showed low sexual dysfunction, they tended to report moderate to poor quality of sexual life. Our findings support the implication that sexual rehabilitation must be provided for women with SCI soon after injury.

COPD and occupational exposures: a case-control study.

PubMed

Weinmann, Sheila; Vollmer, William M; Breen, Victor; Heumann, Michael; Hnizdo, Eva; Villnave, Jacqueline; Doney, Brent; Graziani, Monica; McBurnie, Mary Ann; Buist, A Sonia

2008-05-01

Evidence demonstrates that occupational exposures are causally linked with chronic obstructive pulmonary disease (COPD). This case-control study evaluated the association between occupational exposures and prevalent COPD based on lifetime occupational history. Cases (n = 388) aged 45 years and older with COPD were compared with controls (n = 356), frequency matched on age, sex, and cigarette smoking history. Odds ratios for exposure to each of eight occupational hazard categories and three composite measures of exposure were computed using logistic regression. RESULTSOccupational exposures most strongly associated with COPD were diesel exhaust, irritant gases and vapors, mineral dust, and metal dust. The composite measures describing aggregate exposure to gases, vapors, solvents, or sensitizers (GVSS) and aggregate exposure to dust, GVSS, or diesel exhaust were also associated with COPD. In the small group of never-smokers, a similar pattern was evident. These population-based findings add to the literature linking occupational exposures to COPD.

Does iodine excess lead to hypothyroidism? Evidence from a case-control study in India.

PubMed

Kotwal, Atul; Kotwal, Jyoti; Prakash, Rajat; Kotwal, Narendra

2015-08-01

Iodine deficiency disorders have been known to mankind since antiquity and various researchers elucidated the role of iodine in its causation. However, recent evidence shows that the entire control program ignored multi-causality and association of increased iodine intake with hypothyroidism. This study was conducted to assess differences of iodine intake as measured by urinary iodine excretion (UIE) between cases of hypothyroidism and healthy controls. A case-control study was conducted with three groups (cases, hospital controls and community controls) in two cities of India. Patients with overt hypothyroidism were cases (n = 150) and were compared with age, sex and socioeconomic status-matched hospital (n = 154) and community (n = 488) controls. Thyroid function tests (T3, T4, TSH) were used as diagnostic and inclusion criteria. TPOAb and UIE estimation were carried out for all study participants. Mean values of TPOAb and UIE were higher in cases as compared to hospital controls as well as community controls (p <0.05). With a cut off of 34 IU/mL for TPOAb, more cases had an anti-TPO level >34 as compared to hospital controls (p <0.001) as well as community controls (p <0.001); OR, 0.06 (95% CI, 0.03, 0.12) and 0.08 (0.05, 0.12), respectively. For UIE cut-off of 300 μg/L, more cases than hospital controls (p = 0.090) and community controls (p = 0.001) had higher levels; OR, 0.671, (0.422, 1.066) and 0.509, (0.348, 0.744), respectively. The study has clearly shown that cases of hypothyroidism are associated with excess iodine intake. Cohort studies to generate further evidence and an eco-social epidemiological approach have been suggested as the way forward. Copyright © 2015 IMSS. Published by Elsevier Inc. All rights reserved.

A case-control study of domestic kitchen microbiology and sporadic Salmonella infection.

PubMed

Parry, S M; Slader, J; Humphrey, T; Holmes, B; Guildea, Z; Palmer, S R

2005-10-01

The microbiology of domestic kitchens in the homes of subjects who had suffered sporadic Salmonella infection (cases) was compared with control domestic kitchens. Case and control dishcloths and refrigerator swabs were examined for the presence of Salmonella spp., total Enterobacteriaceae counts and total aerobic colony counts. Salmonella spp. were isolated from both case and control dishcloths and refrigerators but there were no significant differences between the two groups. Colony counts were similar in case and control dishcloths and refrigerator swabs. There was no relationship between the total counts and presence of Salmonella . There was no evidence that cases of Salmonella infection were more likely to have kitchens which were contaminated with these bacteria or have higher bacterial counts than controls. Total bacterial counts were poor indicators of Salmonella contamination of the domestic kitchen environment. Further factors which could not be identified by a study of this design may increase risk of Salmonella food poisoning. These factors may include individual susceptibility of the patient. Alternatively, sporadic cases of Salmonella food poisoning may arise from food prepared outside the home.

Rethinking sources of representative controls for the conduct of case-control studies in minority populations.

PubMed

Bandera, Elisa V; Chandran, Urmila; Zirpoli, Gary; McCann, Susan E; Ciupak, Gregory; Ambrosone, Christine B

2013-05-31

Recruitment of controls remains a challenge in case-control studies and particularly in studies involving minority populations. We compared characteristics of controls recruited through random digit dialing (RDD) to those of community controls enrolled through churches, health events and other outreach sources among women of African ancestry (AA) participating in the Women's Circle of Health Study, a case-control study of breast cancer. Odds ratios and 95% confidence intervals were also computed using unconditional logistic regression to evaluate the impact of including the community controls for selected variables relevant to breast cancer and for which there were significant differences in distribution between the two control groups. Compared to community controls (n=347), RDD controls (n=207) had more years of education and higher income, lower body mass index, were more likely to have private insurance, and less likely to be single. While the percentage of nulliparous women in the two groups was similar, community controls tended to have more children, have their first child at a younger age, and were less likely to breastfeed their children. Dietary intake was similar in the two groups. Compared to census data, the combination of RDD and community controls seems to be more representative of the general population than RDD controls alone. Furthermore, the inclusion of the community group had little impact on the magnitude of risk estimates for most variables, while enhancing statistical power. Community-based recruitment was found to be an efficient and feasible method to recruit AA controls.

Statin use and fatal prostate cancer: a matched case-control study.

PubMed

Marcella, Stephen W; David, Alice; Ohman-Strickland, Pamela A; Carson, Jeffery; Rhoads, George G

2012-08-15

Statins are some of the most commonly prescribed medications in medical practice, and prostate cancer is the most common malignancy among men. Although there has been no consistent evidence that statins affect cancer incidence, including prostate cancer, several reports suggest they may decrease the rate of advanced prostate cancer. However, no study to date has specifically examined statin use and prostate cancer mortality. The authors conducted this population-based case-control investigation to examine this association. This was a matched case-control study. Cases were residents of New Jersey ages 55 to 79 years who died from prostate cancer between 1997 and 2000. The cases were matched individually to population-based controls by 5-year age group and race. Medication data were obtained identically for cases and controls from blinded medical chart review. Conditional logistic regression was used to adjust for confounders. In total, 718 cases were identified, and cooperation was obtained from 77% of their spouses (N = 553). After a review of medical records, 387 men were eligible, and 380 were matched to a control. The unadjusted odds ratio was 0.49 (95% confidence interval, 0.34-0.70) and decreased to 0.37 (P < .0001) after adjusting for education, waist size, body mass index, comorbidities, and antihypertensive medication. There was little difference between lipophilic and hydrophilic statins, but more risk reduction was noted for high-potency statins (73%; P < .0001) compared with low-potency statins (31%; P = .32). Statin use was associated with substantial protection against prostate cancer death, adding to the epidemiologic evidence for an inhibitory effect on prostate cancer. Copyright © 2011 American Cancer Society.

Patterns of anti-inflammatory drug use and risk of dementia: a matched case-control study.

PubMed

Dregan, A; Chowienczyk, P; Armstrong, D

2015-11-01

There is limited primary-care-based evidence about a potential association between anti-inflammatory therapy and dementia subtypes. The present study addressed this limitation by using electronic health records from a large primary care database. A case-control study was implemented using electronic medical records. Cases had a diagnosis of dementia between 1992 and 2014. Up to four controls matched on age, gender, family practice and index date were selected for each case. Use of non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoid drugs represented the exposure variables. Primary outcome measures included all-cause dementia and main dementia subtypes, including Alzheimer disease (AD), vascular dementia (VaD) and Lewy body dementia (LBD). Data were analysed using conditional logistic regression. The study identified 31,083 patients with AD, 23,465 with VaD and 1694 with LBD. Ever-used NSAIDs were associated with a modest increase in the risk of all-cause dementia (odds ratio 1.04, 95% confidence interval 1.02-1.05, P < 0.006), whilst no association was apparent for ever-used glucocorticoids (0.98, 0.96-1.01, P = 0.152). There was no evidence for an association between NSAIDs and AD (1.03, 0.99-1.06, P = 0.07) or LBD (1.13, 0.99-1.29, P = 0.08). However, a significant increase in the risk for VaD (1.33, 1.29-1.38, P < 0.001) was observed. Similar patterns emerged for glucocorticoid therapy. In a large primary care population, there was no robust evidence for a potential association between anti-inflammatory drugs and risk of AD or LBD. NSAIDs and glucocorticoid drugs were associated with higher risk of VaD. © 2015 EAN.

Social capital and adverse treatment outcomes of tuberculosis: a case-control study.

PubMed

Deshmukh, P R; Mundra, A; Dawale, A

2017-08-01

'Social capital' refers to social norms, relationships, networks and values that affect the functioning and development of society. Social capital influences health positively, but its role in the treatment outcomes of tuberculosis (TB) is not known. To study the role of social capital in determining adverse TB treatment outcomes. Of 516 patients registered under the Revised National Tuberculosis Control Programme in 2014 in Wardha Tuberculosis Unit, Wardha, India, we included 88 patients with adverse treatment outcomes as cases and 187 controls from among those without adverse outcomes. Multiple logistic regression was used to compare standardised Z-scores. A greater proportion of controls than cases belonged to higher quartiles of social capital and its domains than cases, and the mean standardised Z-score was also consistently higher among controls than cases. Respectively 47% and 15% of cases and controls were in the poorest quartile of social capital, whereas respectively 10% and 33% of cases and controls were in the richest quartile. Each unit increase in Z-score of overall social capital reduced the odds of adverse treatment outcomes by 63.1%. Appropriate interventions for building social capital for TB patients and linking them with the programme would improve programme performance.

Alcohol consumption and lung cancer risk in never smokers: a pooled analysis of case-control studies.

PubMed

García Lavandeira, José A; Ruano-Ravina, Alberto; Kelsey, Karl T; Torres-Durán, María; Parente-Lamelas, Isaura; Leiro-Fernández, Virginia; Zapata, Maruxa; Abal-Arca, José; Vidal-García, Iria; Montero-Martínez, Carmen; Amenedo, Margarita; Castro-Añón, Olalla; Golpe-Gómez, Antonio; Guzmán-Taveras, Rosirys; Martínez, Cristina; Provencio, Mariano; Mejuto-Martí, María J; García-García, Silvia; Fernández-Villar, Alberto; Piñeiro, María; Barros-Dios, Juan M

2018-06-01

Lung cancer is the deadliest cancer in developed countries but the etiology of lung cancer risk in never smokers (LCRINS) is largely unknown. We aim to assess the effects of alcohol consumption, in its different forms, on LCRINS. We pooled six multi-center case-control studies developed in the northwest of Spain. Cases and controls groups were composed of never smokers. We selected incident cases with anatomopathologically confirmed lung cancer diagnoses. All participants were personally interviewed. We performed two groups of statistical models, applying unconditional logistic regression with generalized additive models. One considered the effect of alcohol type consumption and the other considered the quantity of each alcoholic beverage consumed. A total of 438 cases and 863 controls were included. Median age was 71 and 66, years, respectively. Adenocarcinoma was the predominant histological type, comprising 66% of all cases. We found that any type of wine consumption posed an OR of 2.20 OR 95%CI 1.12-4.35), and spirits consumption had an OR of 1.90 (95%CI 1.13-3.23). Beer consumption had an OR of 1.33 (95%CI 0.82-2.14). These results were similar when women were analyzed separately, but for men there was no apparent risk for any alcoholic beverage. The dose-response analysis for each alcoholic beverage revealed no clear pattern. Wine and spirits consumption might increase the risk of LCRINSs, particularly in females. These results have to be taken with caution given the limitations of the present study.

Design, methodological issues and participation in a multiple sclerosis case-control study.

PubMed

Williamson, D M; Marrie, R A; Ashley-Koch, A; Schiffer, R; Trottier, J; Wagner, L

2012-09-01

This study was conducted to determine whether the risk of developing multiple sclerosis (MS) was associated with certain environmental exposures or genetic factors previously reported to influence MS risk. This paper describes the methodological issues, study design and characteristics of the study population. Individuals with definite MS were identified from a prevalence study conducted in three geographic areas. The target number of cases was not reached, so an additional study area was added. Identifying clinic controls was inefficient, so controls were recruited using random digit dialing. All study participants completed a detailed questionnaire regarding environmental exposures using computer-assisted telephone interviewing, and blood was collected for genetic analysis. In total, 276 cases and 590 controls participated, but participation rates were low, ranging from 28.4% to 38.9%. Only one-third (33.6%) of individuals identified in the prevalence study agreed to participate in the case-control study. Cases were more likely to be non-Hispanic white and older than their source populations as identified in the preceding prevalence study (P < 0.05). Most participants provided a blood sample for genotyping (91%; n = 789). Epidemiological studies play a key role in identifying genetic and environmental factors that are associated with complex diseases like MS. Methodological issues arise in every study, and investigators need to be able to detect, respond to and correct problems in a timely and scientifically valid manner. © 2011 John Wiley & Sons A/S.

Distribution of maternal age and birth order groups in cases with unclassified multiple congenital abnormalities according to the number of component abnormalities: a national population-based case-control study.

PubMed

Csermely, Gyula; Czeizel, Andrew E; Veszprémi, Béla

2015-02-01

Multiple congenital abnormalities are caused by chromosomal aberrations, mutant major genes and teratogens. A minor proportion of these patients are identified as syndromes but the major part belonging to the group of unclassified multiple CAs (UMCAs). The main objective of this study was to evaluate the maternal age and birth order in pregnant women who had offspring affected with UMCA. The strong association between numerical chromosomal aberrations, e.g., Down syndrome and advanced maternal age is well-known and tested here. The Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980 to 1996, yielded a large population-based national data set with 22,843 malformed newborns or fetuses ("informative cases") included 1349 UMCA cases with their 2407 matched controls. Case-control comparison of maternal age and birth order was made for cases with UMCA, stratified by component numbers and their controls. In addition, 834 cases with Down syndrome were compared to 1432 matched controls. The well-known advanced maternal age with the higher risk for Down syndrome was confirmed. The findings of the study suggest that the young age of mothers associates with the higher risk of UMCA, in addition birth order 4 or more associates with the higher risk for UMCA with 2 and 3 component CAs. This study was the first to analyze the possible maternal and birth order effect for cases with UMCA, and the young age and higher birth order associated with a higher risk for UMCA. © 2014 Wiley Periodicals, Inc.

Investigation of occupational and environmental causes of respiratory cancers (ICARE): a multicenter, population-based case-control study in France.

PubMed

Luce, Danièle; Stücker, Isabelle

2011-12-14

Occupational causes of respiratory cancers need to be further investigated: the role of occupational exposures in the aetiology of head and neck cancers remains largely unknown, and there are still substantial uncertainties for a number of suspected lung carcinogens. The main objective of the study is to examine occupational risk factors for lung and head and neck cancers. ICARE is a multi-center, population-based case-control study, which included a group of 2926 lung cancer cases, a group of 2415 head and neck cancer cases, and a common control group of 3555 subjects. Incident cases were identified in collaboration with cancer registries, in 10 geographical areas. The control group was a random sample of the population of these areas, with a distribution by sex and age comparable to that of the cases, and a distribution by socioeconomic status comparable to that of the population. Subjects were interviewed face to face, using a standardized questionnaire collecting particularly information on tobacco and alcohol consumption, residential history and a detailed description of occupational history. Biological samples were also collected from study subjects. The main occupational exposures of interest are asbestos, man-made mineral fibers, formaldehyde, polycyclic aromatic hydrocarbons, chromium and nickel compounds, arsenic, wood dust, textile dust, solvents, strong acids, cutting fluids, silica, diesel fumes, welding fumes. The complete list of exposures of interest includes more than 60 substances. Occupational exposure assessment will use several complementary methods: case-by-case evaluation of exposure by experts; development and use of algorithms to assess exposure from the questionnaires; application of job-exposure matrices. The large number of subjects should allow to uncover exposures associated with moderate increase in risks, and to evaluate risks associated with infrequent or widely dispersed exposures. It will be possible to study joint effects of

Trachoma and Relative Poverty: A Case-Control Study.

PubMed

Habtamu, Esmael; Wondie, Tariku; Aweke, Sintayehu; Tadesse, Zerihun; Zerihun, Mulat; Zewdie, Zebideru; Callahan, Kelly; Emerson, Paul M; Kuper, Hannah; Bailey, Robin L; Mabey, David C W; Rajak, Saul N; Polack, Sarah; Weiss, Helen A; Burton, Matthew J

2015-11-01

Trachoma is widely considered a disease of poverty. Although there are many epidemiological studies linking trachoma to factors normally associated with poverty, formal quantitative data linking trachoma to household economic poverty within endemic communities is very limited. Two hundred people with trachomatous trichiasis were recruited through community-based screening in Amhara Region, Ethiopia. These were individually matched by age and gender to 200 controls without trichiasis, selected randomly from the same sub-village as the case. Household economic poverty was measured through (a) A broad set of asset-based wealth indicators and relative household economic poverty determined by principal component analysis (PCA, (b) Self-rated wealth, and (c) Peer-rated wealth. Activity participation data were collected using a modified 'Stylised Activity List' developed for the World Bank's Living Standards Measurement Survey. Trichiasis cases were more likely to belong to poorer households by all measures: asset-based analysis (OR = 2.79; 95%CI: 2.06-3.78; p<0.0001), self-rated wealth (OR, 4.41, 95%CI, 2.75-7.07; p<0.0001) and peer-rated wealth (OR, 8.22, 95% CI, 4.59-14.72; p<0.0001). Cases had less access to latrines (57% v 76.5%, p = <0.0001) and higher person-to-room density (4.0 v 3.31; P = 0.0204) than the controls. Compared to controls, cases were significantly less likely to participate in economically productive activities regardless of visual impairment and other health problems, more likely to report difficulty in performing activities and more likely to receive assistance in performing productive activities. This study demonstrated a strong association between trachomatous trichiasis and relative poverty, suggesting a bidirectional causative relationship possibly may exist between poverty and trachoma. Implementation of the full SAFE strategy in the context of general improvements might lead to a virtuous cycle of improving health and wealth. Trachoma is a

[Child abuse in Tlaxcala: a case-control study].

PubMed

Herrada-Huidobro, A; Nazar-Beutelspacher, A; Cassaball-Núñez, M; Vega-Ramos, R; Nava-Cruz, C B

1992-01-01

A longitudinal, retrospective and descriptive study about child abuse was carried out in the Hospitals of the Tlaxcala Secretariat of Health, Mexico. The information was obtained from hospitalized children's charts between January first and November 30, 1991. The charts included were those belonging to zero to 14 year old children with injuries, poisoning, and II-III degrees of malnutrition. Four child-abuse criteria were established: physical, sexual, non organic malnutrition and mixed (physical and non organic malnutrition). Two control groups were defined. Different patterns were observed between accidental and non accidental injuries, malnutrition and poisoning among the case and the control groups. The study provides useful information for the integral diagnosis of child abuse in hospitalized children.

Field-based random sampling without a sampling frame: control selection for a case-control study in rural Africa.

PubMed

Crampin, A C; Mwinuka, V; Malema, S S; Glynn, J R; Fine, P E

2001-01-01

Selection bias, particularly of controls, is common in case-control studies and may materially affect the results. Methods of control selection should be tailored both for the risk factors and disease under investigation and for the population being studied. We present here a control selection method devised for a case-control study of tuberculosis in rural Africa (Karonga, northern Malawi) that selects an age/sex frequency-matched random sample of the population, with a geographical distribution in proportion to the population density. We also present an audit of the selection process, and discuss the potential of this method in other settings.

Risk factors and therapy for goat mastitis in a hospital-based case-control study in Bangladesh.

PubMed

Koop, Gerrit; Islam, Md Nurul; Rahman, Md Mizanur; Khatun, Momena; Ferdous, Jinnat; Sayeed, Md Abu; Islam, Shariful; Ahaduzzaman, Md; Akter, Sazeda; Mannan, Abdul; Hassan, Mohammad Mahmudul; Dissanayake, Ravi; Hoque, Md Ahasanul

2016-02-01

Bangladesh has a large population of goats, which contribute to the income, nutrition and welfare of the households of many families. Mastitis in goats has a low incidence, but is often very severe, making veterinary care necessary. The aim of this study was to identify seasonality and risk factors for goat mastitis in a hospital-based matched case-control study in a teaching veterinary hospital in Chittagong, Bangladesh and to describe the range of antimicrobial treatments applied in this situation. Cases of mastitis and controls were drawn from the hospital patient recording system, along with their risk factor status. Multiple imputation was applied to deal with the missing values in the data analysis. Mastitis occurred somewhat more in the rainy season, and comprised about 3% of all goats admitted to the hospital during January 2011-June 2014. Free-ranging farming system, poor body condition score and non-native goat breeds were significantly associated with case status. Treatment of clinical mastitis was variable and unsystematic, but the use of gentamicin was commonly recorded. The need for more prudent and evidence-based antimicrobial therapies is discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Power and sample size for multivariate logistic modeling of unmatched case-control studies.

PubMed

Gail, Mitchell H; Haneuse, Sebastien

2017-01-01

Sample size calculations are needed to design and assess the feasibility of case-control studies. Although such calculations are readily available for simple case-control designs and univariate analyses, there is limited theory and software for multivariate unconditional logistic analysis of case-control data. Here we outline the theory needed to detect scalar exposure effects or scalar interactions while controlling for other covariates in logistic regression. Both analytical and simulation methods are presented, together with links to the corresponding software.

Effectiveness of pneumococcal vaccination for elderly people in Catalonia, Spain: a case-control study.

PubMed

Dominguez, Angela; Salleras, Lluis; Fedson, David S; Izquierdo, Conchita; Ruiz, Laura; Ciruela, Pilar; Fenoll, Asuncion; Casal, Julio

2005-05-01

Observational studies offer an approach to evaluating the effectiveness of vaccination programs. We evaluated the effectiveness of a 23-valent pneumococcal vaccination program for elderly people in Catalonia, Spain, in a matched-set case-control study. We identified 149 cases of invasive pneumococcal disease among patients aged > or =65 years who were hospitalized in 12 large hospitals in Catalonia during the period of 1 January 2001 through 31 March 2002. We selected 2 hospital control patients and 1 outpatient control subject for each case patient, matching on the basis of age and underlying medical conditions. We obtained their pneumococcal vaccination histories and used conditional logistic regression to determine effectiveness of vaccination. Among all 149 cases of invasive pneumococcal disease, 131 (87.9%) were caused by vaccine or vaccine-related serotypes. In the adjusted analysis, overall effectiveness of vaccination against infections due to all serotypes was 70% (95% confidence interval [CI], 48%-82%). Among immunocompetent subjects with or without high-risk conditions, effectiveness of vaccination was 76% (95% CI, 51%-88%), but among immunocompromised subjects it was 50% (95% CI, -44% to 82%). Among subjects with infections due to vaccine or vaccine-related serotypes, effectiveness of vaccination was 72% (95% CI, 50%-85%) overall and 78% (95% CI, 50%-90%) in those who were immunocompetent, but it was only 46% (95% CI, -54% to 81%) in those who were immunocompromised. Overall effectiveness of vaccination was 65% (95% CI, 35%-81%) during the noninfluenza period. Pneumococcal vaccination was effective in preventing invasive pneumococcal disease among all elderly persons in Catalonia. Effectiveness was greater in immunocompetent persons, most of whom had underlying high-risk conditions. The number of subjects was too small to determine whether vaccination was effective in those who were immunocompromised.

Statin Use and Fatal Prostate Cancer: A Matched Case-Control Study

PubMed Central

Marcella, Stephen W.; David, Alice; Ohman-Strickland, Pamela A.; Carson, Jeffery; Rhoads, George G.

2015-01-01

Background Statins are one of the most commonly prescribed medications in medical practice and prostate cancer is the most common male malignancy. While there has been no consistent evidence that statins affect cancer incidence, including prostate cancer, several reports suggest they may decrease the rate of advanced prostate cancer. However, no study has examined statin use and prostate cancer mortality specifically. We report here a population-based case-control investigation that examines this association. Methods We conducted a matched case-control study. Cases were residents of New Jersey ages 55 – 79 who died from prostate cancer between 1997–2000. We individually matched population-based controls by five-year age-group and race. Medication data were obtained identically for cases and controls from blinded medical chart review. We used conditional logistic regression to adjust for confounders. Results We identified 718 cases and obtained cooperation from 77% of their spouses (N=553). After review of medical records, 387 were eligible and 380 were matched to a control. The unadjusted odds ratio was 0.49 (95% CI, 0.34–0.70) which decreased to 0.37 (p<0.0001) after adjustment for education, waist size, BMI, comorbidities, and anti-hypertensive medication. There was little difference between lipophilic and hydrophilic statins but more risk reduction was noted for hi-potency statins (73%, p<0.0001) as compared to low-potency statins (31%, p=0.32). Conclusion Statin use is associated with substantial protection against prostate cancer death, adding to the epidemiologic evidence for an inhibitory effect on prostate cancer. PMID:22180145

Assessing different measures of population-level vaccine protection using a case-control study.

PubMed

Ali, Mohammad; You, Young Ae; Kanungo, Suman; Manna, Byomkesh; Deen, Jacqueline L; Lopez, Anna Lena; Wierzba, Thomas F; Bhattacharya, Sujit K; Sur, Dipika; Clemens, John D

2015-11-27

Case-control studies have not been examined for their utility in assessing population-level vaccine protection in individually randomized trials. We used the data of a randomized, placebo-controlled trial of a cholera vaccine to compare the results of case-control analyses with those of cohort analyses. Cases of cholera were selected from the trial population followed for three years following dosing. For each case, we selected 4 age-matched controls who had not developed cholera. For each case and control, GIS was used to calculate vaccine coverage of individuals in a surrounding "virtual" cluster. Specific selection strategies were used to evaluate the vaccine protective effects. 66,900 out of 108,389 individuals received two doses of the assigned regimen. For direct protection among subjects in low vaccine coverage clusters, we observed 78% (95% CI: 47-91%) protection in a cohort analysis and 84% (95% CI: 60-94%) in case-control analysis after adjusting for confounding factors. Using our GIS-based approach, estimated indirect protection was 52% (95% CI: 10-74%) in cohort and 76% (95% CI: 47-89%) in case control analysis. Estimates of total and overall effectiveness were similar for cohort and case-control analyses. The findings show that case-control analyses of individually randomized vaccine trials may be used to evaluate direct as well as population-level vaccine protection. Copyright © 2015. Published by Elsevier Ltd.

Occupational risk factors for mycosis fungoides: a European multicenter case-control study.

PubMed

Morales-Suárez-Varela, Maria M; Olsen, Jorn; Johansen, Preben; Kaerlev, Linda; Guénel, Pascal; Arveux, Patrick; Wingren, Gun; Hardell, Lennart; Ahrens, Wolfgang; Stang, Andreas; Llopis, Agustin; Merletti, Franco; Aurrekoetxea, Juan Jose; Masala, Giovanna

2004-03-01

Mycosis fungoides (MF) is a rare disease with an unknown etiology. Its distribution suggests that occupational exposures may play a role. In the present study, we searched for occupational factors associated with MF. A European multicenter case-control study on seven rare cancers, including MF, was conducted from 1995 to 1997. Patients between 35 and 69 years of age diagnosed with MF (n = 134) were identified and their diagnoses were checked by a reference pathologist who classified 83 cases as definitive, 35 cases as possible, and 16 cases as not histologically verified. Of the 118 histologically verified cases, 104 were interviewed, of which 76 were definitive cases. As controls, we selected population controls and colon cancer controls to serve all seven case groups. Altogether, 833 colon cancer controls and 2071 population controls were interviewed. The response rate was 91.5% for cases (76 of the 83 definitive cases), and 66.6% for controls. A high risk of MF for men was observed in the industries of other non-metallic mineral products (Odds Ratio [OR] 5.3, 95% confidence interval [CI] = 1.7-16.2) and of wholesale trade (OR 3.6, 95% CI = 1.3-10.5). A high risk was found for female employees in the sector of pulp paper manufacture (OR 14.4, 95% CI = 2.2-95.1). The male occupations with the highest risks were glass formers, potters, and ceramics workers (OR 17.9, 95% CI = 5.4-59.4) and technical salesmen (OR 8.6, 95% CI = 2.4-30.8). For women, the occupations associated with the highest risks were government executives (OR 4.8, 95% CI = 1.0-22.6) and railway and road vehicles loaders (OR 3.9, 95% CI = 1.0-14.0). The results suggest that some occupational factors are associated with MF. Working as glass formers, pottery, and ceramics workers carried the highest risk, and these findings deserve further attention and replication. Females working in the paper and pulp industries may also be exposed to carcinogens of relevance to MF.

Controls on Water Use for Thermoelectric Generation: Case Study Texas, U.S.

PubMed Central

2013-01-01

Large-scale U.S. dependence on thermoelectric (steam electric) generation requiring water for cooling underscores the need to understand controls on this water use. The study objective was to quantify water consumption and withdrawal for thermoelectric generation, identifying controls, using Texas as a case study. Water consumption for thermoelectricity in Texas in 2010 totaled ∼0.43 million acre feet (maf; 0.53 km3), accounting for ∼4% of total state water consumption. High water withdrawals (26.2 maf, 32.3 km3) mostly reflect circulation between ponds and power plants, with only two-thirds of this water required for cooling. Controls on water consumption include (1) generator technology/thermal efficiency and (2) cooling system, resulting in statewide consumption intensity for natural gas combined cycle generators with mostly cooling towers (0.19 gal/kWh) being 63% lower than that of traditional coal, nuclear, or natural gas steam turbine generators with mostly cooling ponds (0.52 gal/kWh). The primary control on water withdrawals is cooling system, with ∼2 orders of magnitude lower withdrawals for cooling towers relative to once-through ponds statewide. Increases in natural gas combined cycle plants with cooling towers in response to high production of low-cost natural gas has greatly reduced water demand for thermoelectric cooling since 2000. PMID:23937226

Childhood leukaemia and distance from power lines in California: a population-based case-control study

PubMed Central

Crespi, Catherine M; Vergara, Ximena P; Hooper, Chris; Oksuzyan, Sona; Wu, Sheng; Cockburn, Myles; Kheifets, Leeka

2016-01-01

Background: Studies have reported an increased risk of childhood leukaemia associated with living near high-voltage electric power transmission lines that extend to distances at which magnetic fields from lines are negligible. We conducted a large records-based case-control study of childhood leukaemia risk in the population living near power lines in California. Methods: The study included 5788 childhood leukaemia and 3308 central nervous system (CNS) cancer cases (for comparison) born in and diagnosed in California (1986–2008), and matched to population-based controls by age and sex. We geocoded birth address and estimated the distance from residence to transmission lines using geographic information systems, aerial imagery, and, for some residences, site visits. Results: For leukaemia, there was a slight excess of cases within 50 m of a transmission line over 200 kV (odds ratio 1.4, 95% confidence interval 0.7–2.7). There was no evidence of increased risk for distances beyond 50 m, for lower-voltage lines, or for CNS cancers. Conclusions: Our findings did not clearly support an increased childhood leukaemia risk associated with close proximity (<50 m) to higher voltage lines, but could be consistent with a small increased risk. Reports of increased risk for distances beyond 50 m were not replicated. PMID:27219016

A community-based, case-control study of childhood stroke risk associated with congenital heart disease

PubMed Central

Fox, Christine K.; Sidney, Stephen; Fullerton, Heather J.

2014-01-01

Background and Purpose A better understanding of the stroke risk factors in children with congenital heart disease (CHD) could inform stroke prevention strategies. We analyzed pediatric stroke associated with CHD in a large community-based, case-control study. Methods From 2.5 million children (< 20 years) enrolled in a Northern California integrated healthcare plan, we identified ischemic and hemorrhagic strokes and randomly selected age and facility-matched stroke-free controls (3 per case). We determined exposure to CHD (diagnosed prior to stroke) and used conditional logistic regression to analyze stroke risk. Results CHD was identified in 15/412 cases (4%) versus 7/1,236 controls (0.6%). Children (28 days – 20 years) with CHD had 19-fold (Odds Ratio [OR] 19; 95% Confidence Interval [CI] 4.2, 83) increased stroke risk compared to controls. History of CHD surgery was associated with >30-fold increased risk of stroke (OR 31; CI 4, 241 compared to controls). After excluding peri-operative strokes, a history of CHD surgery still increased childhood stroke risk (OR 13; CI 1.5, 114). The majority of children with stroke and CHD were outpatient at the time of stroke, and almost half the cases who underwent cardiac surgery had their stroke >5 years after the most recent procedure. An estimated 7% of ischemic and 2% of hemorrhagic childhood strokes in the population were attributable to CHD. Conclusions CHD is an important childhood stroke risk factor. Children who undergo CHD surgery remain at elevated risk outside of the peri-operative period, and would benefit from optimized long-term stroke prevention strategies. PMID:25516197

Hygiene behaviour and hospitalized severe childhood diarrhoea: a case-control study.

PubMed

Baltazar, J C; Tiglao, T V; Tempongko, S B

1993-01-01

The relationship between personal and domestic hygiene behaviour and hospitalized childhood diarrhoea was examined in a case-control study of 356 cases and 357 controls from low-income families in metropolitan Manila. Indices of hygiene behaviour were defined for overall cleanliness, kitchen hygiene, and living conditions. Only the indices for overall cleanliness and kitchen hygiene were significantly associated with diarrhoea. An increasing excess risk of hospitalization with severe diarrhoea was noted as the ratings for standards of hygiene became lower, and this excess risk persisted even after controlling for confounding variables. The implications of our findings for the control of diarrhoeal disease are discussed.

Hygiene behaviour and hospitalized severe childhood diarrhoea: a case-control study.

PubMed Central

Baltazar, J. C.; Tiglao, T. V.; Tempongko, S. B.

1993-01-01

The relationship between personal and domestic hygiene behaviour and hospitalized childhood diarrhoea was examined in a case-control study of 356 cases and 357 controls from low-income families in metropolitan Manila. Indices of hygiene behaviour were defined for overall cleanliness, kitchen hygiene, and living conditions. Only the indices for overall cleanliness and kitchen hygiene were significantly associated with diarrhoea. An increasing excess risk of hospitalization with severe diarrhoea was noted as the ratings for standards of hygiene became lower, and this excess risk persisted even after controlling for confounding variables. The implications of our findings for the control of diarrhoeal disease are discussed. PMID:8324851

Senna treatment in pregnant women and congenital abnormalities in their offspring--a population-based case-control study.

PubMed

Acs, Nándor; Bánhidy, Ferenc; Puhó, Erzsébet H; Czeizel, Andrew E

2009-07-01

Previously, the possible teratogenic effect of frequently used laxative drug, senna has not been checked in case-control epidemiological study. Objective of the study was the comparison of cases with congenital abnormalities (CAs) and their matched controls without CAs in the population-based large data set of the Hungarian Case-Control Surveillance System of Congenital Abnormalities. Of 22,843 cases with CA, 506 (2.2%) had mothers with senna treatment, while of 38,151 control newborn infants without CA, 937 (2.5%) were born to mothers with senna treatment (adjusted OR with 95% CI: 1.0, 0.9-1.1), and of 834 malformed controls with Down syndrome, 26 (3.1%) had mothers with the use of senna (OR with 95% CI: 0.7, 0.5-1.1). The range of senna doses was between 10mg and 30 mg, but most pregnant women used 20mg daily. The mothers with senna treatment showed the characteristics of pregnant women with constipation (elder with larger proportion of primiparae). There was no higher risk for 23 different CA groups after the senna treatment during the second and/or third gestational month of 260 mothers, i.e. in the critical period of most major CAs, compared with their 500 matched controls. Gestational age at delivery was somewhat longer (0.2 week) and the rate of preterm birth was lower (6.6% vs. 9.2%) in newborn infants without CA born to mothers with senna treatment compared with babies born to mothers without senna treatment. In conclusion, senna treatment did not associate with a higher risk of CAs in the offspring of pregnant women with constipation.

Medical and drug risk factors associated with neuroblastoma: a case-control study.

PubMed

Kramer, S; Ward, E; Meadows, A T; Malone, K E

1987-05-01

A matched case-control study of prenatal risk factors for neuroblastoma was conducted, including 104 cases diagnosed over the period 1970-79 in the Greater Delaware Valley. Significantly elevated odds ratios (ORs) were associated with maternal use of a neurally active drug during pregnancy (OR = 2.83), sex hormone exposure 3 months prior to or during pregnancy (OR = 2.25), frequent alcohol consumption during pregnancy (OR = 9.0), and maternal use of diuretic drugs during pregnancy (OR = 5.75). Significantly more case mothers than control mothers reported use of hair coloring products during pregnancy (OR = 3.0). No association was found between cigarette smoking, coffee consumption, or medical irradiation and case-control status.

Nutrient intake and gastric cancer risk: a case-control study in Spain.

PubMed

Ramón, J M; Serra-Majem, L; Cerdó, C; Oromí, J

1993-12-01

A case-control study of dietary factors and gastric cancer was conducted between September 1986 and March 1989 in the Barcelona metropolitan area, Spain. In all 117 cases with histologically confirmed diagnosis of gastric adenocarcinoma were matched on sex, age and possession of a telephone to 234 population controls. Of the controls 188 (80.3%) were selected by random digit telephone dialing and 46 (19.7%) by neighbourhood of residence. Information about frequency and amount of consumption of 89 alimentary items was gathered by questionnaire, and cases and controls were interviewed in their homes by trained interviewers. The gastric cancer risk decreased in proportion to vitamin C intake. In multivariate analysis adjusting for major covariables, energy and vitamin A intake, the estimated odds ratio (OR) for the upper quartile of vitamin C intake was 0.3 (95% confidence interval [CI]: 0.1-0.8). After adjustment for major covariables, calories and vitamin C intake, vitamin A did not show significant association with the gastric cancer risk. Our findings are consistent with previous case-control studies and with the hypothesis that vitamin C may inhibit the intragastric nitrosation process.

A concordance index for matched case-control studies with applications in cancer risk.

PubMed

Brentnall, Adam R; Cuzick, Jack; Field, John; Duffy, Stephen W

2015-02-10

In unmatched case-control studies, the area under the receiver operating characteristic (ROC) curve (AUC) may be used to measure how well a variable discriminates between cases and controls. The AUC is sometimes used in matched case-control studies by ignoring matching, but it lacks interpretation because it is not based on an estimate of the ROC for the population of interest. We introduce an alternative measure of discrimination that is the concordance of risk factors conditional on the matching factors. Parametric and non-parametric estimators are given for different matching scenarios, and applied to real data from breast and lung cancer case-control studies. Diagnostic plots to verify the constancy of discrimination over matching factors are demonstrated. The proposed simple measure is easy to use, interpret, more efficient than unmatched AUC statistics and may be applied to compare the conditional discrimination performance of risk factors. Copyright © 2014 John Wiley & Sons, Ltd.

Risk factors for late onset gram-negative infections: a case-control study.

PubMed

Samanta, Srabani; Farrer, Kate; Breathnach, Aodhan; Heath, Paul T

2011-01-01

To determine the incidence, mortality and risk factors for neonatal late onset gram-negative sepsis and meningitis (LOGNS). Retrospective case-control study. Tertiary neonatal unit in London. Consecutive inborn infants with late onset (>48 h of life) invasive gram-negative infections diagnosed between 1999 and 2005. Controls were healthy infants matched for gestation and time of admission to the neonatal unit. Clinical and risk factor data. 73 cases of LOGNS were identified of which 48 were inborn and included in the study (incidence 1.85/1000 live births). Enterobacter spp. (28%), Escherichia coli (27%) and Klebsiella spp. (21%) were the most common pathogens. The majority of infants were of very low birthweight (VLBW; 79%), and cases and controls were well matched (median gestation 26 weeks). Overall case death was 27% in cases versus 13.5% in controls (p=0.08). There was no significant difference between cases and controls regarding maternal risk factors. Mechanical ventilation, total parenteral nutrition (TPN) and its duration, presence of a central venous line and its duration, use of specific antibiotics and the occurrence of necrotising enterocolitis at or before the first positive culture were all significantly associated with case status in univariate analysis. In multivariate logistic regression analysis, only duration of TPN at or before first positive blood culture remained independently associated with LOGNS (p<0.001). LOGNS occurs predominantly in VLBW infants. When the influence of gestational age is accounted for, the only independent risk factor found for late onset gram-negative neonatal infections is the duration of TPN.

Acrylamide Hemoglobin Adduct Levels and Ovarian Cancer Risk: a nested case-control study

PubMed Central

Xie, Jing; Terry, Kathryn L.; Poole, Elizabeth M.; Wilson, Kathryn M.; Rosner, Bernard A.; Willett, Walter C.; Vesper, Hubert W.; Tworoger, Shelley S.

2013-01-01

Background Acrylamide is a probable human carcinogen formed during cooking of starchy foods. Two large prospective cohort studies of dietary acrylamide intake and ovarian cancer risk observed a positive association, although two other studies reported no association. Methods We measured acrylamide exposure using red blood cell acrylamide and glycidamide hemoglobin adducts among women in two large prospective cohorts: the Nurses’ Health Study and Nurses’ Health Study II. Between blood collection and 2010, we identified 263 incident cases of epithelial ovarian cancer, matching two controls per case. We used logistic regression models to examine the association between acrylamide exposure and ovarian cancer risk, adjusting for matching factors, family history of ovarian cancer, tubal ligation, oral contraceptive use, body mass index (BMI), parity, alcohol intake, smoking, physical activity, and caffeine intake. Results The multivariate-adjusted relative risk (RR) of ovarian cancer comparing the highest versus lowest tertile of total acrylamide adducts was 0.79 (95% CI: 0.50–1.24, P trend = 0.08). The comparable RR of ovarian cancer among non-smokers at blood draw was 0.85 (95% CI: 0.57–1.27, P trend =0.14). The association did not differ by tumor histology (serous invasive versus not), P for heterogeneity=0.41. Individual adduct types (acrylamide or glycidamide) were not associated with risk. Conclusions We observed no evidence that acrylamide exposure as measured by adducts to hemoglobin is associated with an increased risk of ovarian cancer. Impact Our finding indicates that acrylamide intake may not increase risk of ovarian cancer. PMID:23417989

UK case control study of brain tumours in children, teenagers and young adults: a pilot study.

PubMed

Feltbower, Richard G; Fleming, Sarah J; Picton, Susan V; Alston, Robert D; Morgan, Diana; Achilles, Janice; McKinney, Patricia A; Birch, Jillian M

2014-01-08

Tumours of the central nervous system are the second most common group of childhood cancers in 0-14 year olds (24% of total cancers) and represent a major diagnostic group in 15-24 year olds. The pilot case-control study aimed to establish methodologies for a future comprehensive aetiological investigation among children and young adults. Eligible cases were newly diagnosed with an intracranial tumour of neuroepithelial tissue aged 0-24 years. The pilot recruited patients through Leeds and Manchester Principal Treatment Centres. Controls were drawn from general practice lists. Controls were frequency matched by age and gender. We interviewed 49 cases and 78 controls comprising 85% of the target sample size. Response rates were 52% for cases and 32% for controls. Completion of the questionnaire was successful, with a very small proportion of missing data being reported (5-10%). The age distribution of cases and controls was similar with around three-quarters of interviewed subjects aged 0-14. Half of cases and almost two-thirds of controls reported using a mobile phone with the majority starting between 10-14 years of age. Prevalence of breastfeeding was lower in cases than controls (Odds Ratio 0.4; 95% CI 0.2-1.2), whilst cases were more likely to be delivered by caesarean section (OR 1.6; 95% CI 0.6-4.4). Cases were significantly more likely to have a birthweight > 3.5 kg compared to controls. Cases were also more likely to come from a family with 3 or more siblings than controls (OR 3.0; 95% CI 0.7-13.6). The majority of participants (>80%) were in favour of taking either blood or saliva to aid molecular epidemiological research. Successful methods were established for identifying and recruiting a high proportion of case subjects, exploiting strong links with the clinical teams at the treatment centres. Control procedures proved more difficult to implement. However, working closely with national clinical and professional research networks will enable improved

Bias due to differential participation in case-control studies and review of available approaches for adjustment.

PubMed

Aigner, Annette; Grittner, Ulrike; Becher, Heiko

2018-01-01

Low response rates in epidemiologic research potentially lead to the recruitment of a non-representative sample of controls in case-control studies. Problems in the unbiased estimation of odds ratios arise when characteristics causing the probability of participation are associated with exposure and outcome. This is a specific setting of selection bias and a realistic hazard in many case-control studies. This paper formally describes the problem and shows its potential extent, reviews existing approaches for bias adjustment applicable under certain conditions, compares and applies them. We focus on two scenarios: a characteristic C causing differential participation of controls is linked to the outcome through its association with risk factor E (scenario I), and C is additionally a genuine risk factor itself (scenario II). We further assume external data sources are available which provide an unbiased estimate of C in the underlying population. Given these scenarios, we (i) review available approaches and their performance in the setting of bias due to differential participation; (ii) describe two existing approaches to correct for the bias in both scenarios in more detail; (iii) present the magnitude of the resulting bias by simulation if the selection of a non-representative sample is ignored; and (iv) demonstrate the approaches' application via data from a case-control study on stroke. The bias of the effect measure for variable E in scenario I and C in scenario II can be large and should therefore be adjusted for in any analysis. It is positively associated with the difference in response rates between groups of the characteristic causing differential participation, and inversely associated with the total response rate in the controls. Adjustment in a standard logistic regression framework is possible in both scenarios if the population distribution of the characteristic causing differential participation is known or can be approximated well.

Cannabis use and risk of lung cancer: a case-control study.

PubMed

Aldington, S; Harwood, M; Cox, B; Weatherall, M; Beckert, L; Hansell, A; Pritchard, A; Robinson, G; Beasley, R

2008-02-01

The aim of the present study was to determine the risk of lung cancer associated with cannabis smoking. A case-control study of lung cancer in adults Cases were identified from the New Zealand Cancer Registry and hospital databases. Controls were randomly selected from the electoral roll, with frequency matching to cases in 5-yr age groups and district health boards. Interviewer-administered questionnaires were used to assess possible risk factors, including cannabis use. The relative risk of lung cancer associated with cannabis smoking was estimated by logistic regression. In total, 79 cases of lung cancer and 324 controls were included in the study. The risk of lung cancer increased 8% (95% confidence interval (CI) 2-15) for each joint-yr of cannabis smoking, after adjustment for confounding variables including cigarette smoking, and 7% (95% CI 5-9) for each pack-yr of cigarette smoking, after adjustment for confounding variables including cannabis smoking. The highest tertile of cannabis use was associated with an increased risk of lung cancer (relative risk 5.7 (95% CI 1.5-21.6)), after adjustment for confounding variables including cigarette smoking. In conclusion, the results of the present study indicate that long-term cannabis use increases the risk of lung cancer in young adults.

Medication exposure and spontaneous abortion: a case-control study using a French medical database.

PubMed

Abadie, D; Hurault-Delarue, C; Damase-Michel, C; Montastruc, J L; Lacroix, I

2015-01-01

Few studies have been conducted to investigate drug effects on spontaneous abortion risk. The objective of the present study was to evaluate the potential association between first trimester drug exposure and spontaneous abortion occurrence. The authors performed a nested case-control study using data from TERAPPEL, a French medical database. Cases were the women who had a spontaneous abortion (before the 22nd week of amenorrhea) and controls were women who gave birth to a child. Analyzed variables were: maternal age, obstetric history, tobacco, and alcohol and drug consumption during the first trimester of pregnancy. For comparison of drug exposures between cases and controls, the authors calculated odds ratios (ORs) by means of multivariate logistic regressions adjusted on age and on other drug exposures. The study included 838 cases and 4,508 controls that were identified in the database. In adjusted analyses, cases were more exposed than controls to "non-selective monoamine reuptake inhibitors" [OR=2.2 (CI 95% 1.5-3.3)], "antiprotozoals" [OR = 1.6 (CI 95% 1.1 - 2.5)] and "centrally acting antiobesity products" [OR = 3.4 (CI 95% 1.9 - 6.2)]. Conversely, controls were more exposed than cases to H1 antihistamines [OR = 0.6 (CI 95% 0.4 - 0.9)]. This exploratory study highlights some potential associations between first trimester drug exposure and risk of spontaneous abortion. Further studies have to be carried out to investigate these findings.

Study design options in evaluating gene-environment interactions: practical considerations for a planned case-control study of pediatric leukemia.

PubMed

Goodman, Michael; Dana Flanders, W

2007-04-01

We compare methodological approaches for evaluating gene-environment interaction using a planned study of pediatric leukemia as a practical example. We considered three design options: a full case-control study (Option I), a case-only study (Option II), and a partial case-control study (Option III), in which information on controls is limited to environmental exposure only. For each design option we determined its ability to measure the main effects of environmental factor E and genetic factor G, and the interaction between E and G. Using the leukemia study example, we calculated sample sizes required to detect and odds ratio (OR) of 2.0 for E alone, an OR of 10 for G alone and an interaction G x E of 3. Option I allows measuring both main effects and interaction, but requires a total sample size of 1,500 cases and 1,500 controls. Option II allows measuring only interaction, but requires just 121 cases. Option III allows calculating the main effect of E, and interaction, but not the main effect of G, and requires a total of 156 cases and 133 controls. In this case, the partial case-control study (Option III) appears to be more efficient with respect to its ability to answer the research questions for the amount of resources required. The design options considered in this example are not limited to observational epidemiology and may be applicable in studies of pharmacogenomics, survivorship, and other areas of pediatric ALL research.

Unmatched Case-Control Study on Late Presentation of HIV Infection in Santiago, Cape Verde (2004-2011).

PubMed

Moreira, António L; Fronteira, Inês; Augusto, Gonçalo Figueiredo; Martins, Maria Rosario O

2016-03-15

Access to free antiretroviral therapy (ART) in Sub-Saharan Africa has been steadily increasing over the past decade. However, the success of large-scale ART programmes depends on timely diagnosis and early initiation of HIV care. This study characterizes late presenters to HIV care in Santiago (Cape Verde) between 2004 and 2011, and identifies factors associated with late presentation for care. We defined late presentation as persons presenting to HIV care with a CD4 count below 350 cells/mm³. An unmatched case-control study was conducted using socio-demographic and behavioural data of 368 individuals (191 cases and 177 controls) collected through an interviewer-administered questionnaire, comparing HIV patients late and early presented to care. Logistic regression was performed to estimate odds ratio and 95% confidence intervals. Results show that 51.9% were late presenters for HIV. No differences were found in gender distribution, marital status, or access to health services between cases and controls. Participants who undertook an HIV test by doctor indication were more likely to present late compared with those who tested for HIV by their own initiative. Also, individuals taking less time to initiate ART are more likely to present late. This study highlights the need to better understand reasons for late presentation to HIV care in Cape Verde. People in older age groups should be targeted in future approaches focused on late presenters to HIV care.

On the Analysis of Case-Control Studies in Cluster-correlated Data Settings.

PubMed

Haneuse, Sebastien; Rivera-Rodriguez, Claudia

2018-01-01

In resource-limited settings, long-term evaluation of national antiretroviral treatment (ART) programs often relies on aggregated data, the analysis of which may be subject to ecological bias. As researchers and policy makers consider evaluating individual-level outcomes such as treatment adherence or mortality, the well-known case-control design is appealing in that it provides efficiency gains over random sampling. In the context that motivates this article, valid estimation and inference requires acknowledging any clustering, although, to our knowledge, no statistical methods have been published for the analysis of case-control data for which the underlying population exhibits clustering. Furthermore, in the specific context of an ongoing collaboration in Malawi, rather than performing case-control sampling across all clinics, case-control sampling within clinics has been suggested as a more practical strategy. To our knowledge, although similar outcome-dependent sampling schemes have been described in the literature, a case-control design specific to correlated data settings is new. In this article, we describe this design, discuss balanced versus unbalanced sampling techniques, and provide a general approach to analyzing case-control studies in cluster-correlated settings based on inverse probability-weighted generalized estimating equations. Inference is based on a robust sandwich estimator with correlation parameters estimated to ensure appropriate accounting of the outcome-dependent sampling scheme. We conduct comprehensive simulations, based in part on real data on a sample of N = 78,155 program registrants in Malawi between 2005 and 2007, to evaluate small-sample operating characteristics and potential trade-offs associated with standard case-control sampling or when case-control sampling is performed within clusters.

Risk Factors Profile of Shoulder Dystocia in Oman: A Case Control Study

PubMed Central

Al-Khaduri, Maha M.; Abudraz, Rania Mohammed; Al-Farsi, Yahya M.

2014-01-01

Objective This study aimed to assess the risk factor profile of shoulder dystocia and associated neonatal complications in Oman, a developing Arab country. Methods A retrospective case-control study was conducted among 111 cases with dystocia and 111 controls, identified during 1994-2006 period in a tertiary care hospital in Oman. Controls were randomly selected among women who did not have dystocia, and were matched to cases on the day of delivery. Data related to potential risk factors, delivery, and obstetric complications were collected. Results Dystocia was significantly associated with older maternal age, higher parity, larger BMI, diabetes, and previous record of dystocia. In addition, dystocia was associated more with vacuum and forceps deliveries. Routine traction (51%) was the most used manoeuvre. Among dystocia cases, 13% were associated with fetal complications of which Erb’s Palsy was the most prevalent (79%). Conclusion Our finding of significant associations with risk factors lays out the ground to develop a predictability index for shoulder dystocia, which would help in making it preventable. Further p rospective studies are required to confirm the obtained results. PMID:25337307

[Lung cancer and smoking in Asturias, Spain. A case-control study].

PubMed

Caicoya, M; Mirón, J A

2003-01-01

Lung cancer in Asturias is 1.4-fold greater than the Spanish average, while the proportion of smokers is similar. The objective of this study was to examine the relationship between lung cancer and smoking in Asturias. We performed a hospital-based, incident case control study. The cases were newly diagnosed lung cancer patients and controls were patients from the surgical wards. Information was sought on smoking, occupational exposures, and demographic variables. The analysis was performed by means of odds ratios (OR). One hundred ninety-seven cases and 196 controls were included in the analysis. The adjusted OR of cigarette smoking was 5.77 (95% CI, 2.96-11.22). The risk increased with the number of cigarettes smoked per day (chi 2 = 56.3), the number of packs/year (chi 2 = 48.4), and the age at which smoking started (chi 2 = 76.5). The OR diminished with the number of years of cessation (chi 2 = 39.9). The relationship between smoking and lung cancer in Asturias is similar to that found in other studies carried out in other parts of the western world. The magnitude of the OR may explain the frequency of lung cancer in Asturias. Greater efforts should be devoted to controlling this problem.

First case-control study of zoonotic brucellosis in Gafsa district, Southwest Tunisia.

PubMed

Khamassi Khbou, Médiha; Htira, Samaher; Harabech, Kaouther; Benzarti, M'hammed

2018-06-01

A case-control study was conducted, aimed to describe the clinical human brucellosis (CHB) pattern during 2015 in the Gafsa region (Southwest Tunisia) and to investigate the main risk factors involved in the disease occurrence. One hundred and four CHB cases were notified in 2015 in Gafsa district. All CHB cases that own ruminants were contacted, but only 32 accepted to participate in a matched case-control study. Thirty-two and thirty-one CHB cases and controls, respectively, were included in the study. The subjects were interviewed using a structured questionnaire. A total of 662 domestic ruminants (cattle, sheep and goats) belonging to cases and controls, were screened using the Rose Bengal Test, as recommended by the World Organisation of Animal Health. During 2015, the incidence of CHB was estimated to 30.8 per 100,000 inhabitants affecting mainly males aged between 30 and 39 years. The overall animal seropositivity to Brucella , was 21 and 1.9% in case and control farms, respectively (p < 0.0001). Only five risk factors were found to be significant: overall animal seropositivity (OR = 65.2; 95%CI: 13.3-318.7); handling aborted females (OR = 43.1; 95%CI: 8.3-222.7); presence of male ruminants in the herds (OR = 18.5; 95%CI: 5.18-66); owning seropositive goats (OR = 18.3; 95%CI: 2.4-137.6), owning seropositive sheep (OR = 9.66; 95%CI: 2.9-31.5) and history of abortion during the previous year in the herd (OR = 4.6; 95%CI: 1.3-12.6). Vaccination of animals against brucellosis was associated with lower odds of human brucellosis (OR = 0.03; 95%CI: 0.004-0.2). Raw milk and derivatives consumption was not a risk factor of human brucellosis. Based on this study, ruminants' vaccination coverage should be increased by enhancing the number of vaccinated animals and systematically including male ruminants in Tunisia. Comprehensive education programmes targeting both farmers and general population should be implemented.

Analysis of single nucleotide polymorphisms in case-control studies.

PubMed

Li, Yonghong; Shiffman, Dov; Oberbauer, Rainer

2011-01-01

Single nucleotide polymorphisms (SNPs) are the most common type of genetic variants in the human genome. SNPs are known to modify susceptibility to complex diseases. We describe and discuss methods used to identify SNPs associated with disease in case-control studies. An outline on study population selection, sample collection and genotyping platforms is presented, complemented by SNP selection, data preprocessing and analysis.

Association between glioma and history of allergies, asthma, and eczema: a case-control study with three groups of controls

PubMed Central

Il’yasova, Dora; McCarthy, Bridget; Marcello, Jennifer; Schildkraut, Joellen M.; Moorman, Patricia G.; Krishnamachari, Bhuma; Ali-Osman, Francis; Bigner, Darell D.; Davis, Faith

2009-01-01

Because glioma etiology is largely unknown, the inverse association of glioma risk with atopic conditions is promising and deserves close scrutiny. We examined the association between a history of allergies, asthma, and eczema and glioma risk using sibling, friend, and clinic-based controls. This analysis included 388 incident glioma cases and 80 sibling, 191 friend, and 177 clinic-based controls. Each subject’s medical history was assessed via a web-based or telephone survey. Odds ratios (ORs) and their 95% confidence intervals for the associations with allergies, asthma, eczema, and the overall number of these conditions were calculated from conditional (for sibling and friend controls) and unconditional (for clinic-based controls) logistic models. Allergies were consistently inversely associated with the glioma: ORs were 0.53 (95% CI, 0.15–1.84), 0.54 (95% CI, 0.28–1.07), and 0.34 (95% CI, 0.23–0.50) with sibling, friend, and clinic-based controls, respectively. Asthma showed an inverse association only in the comparison with sibling controls (OR=0.43; 95% CI, 0.19–1.00). Eczema showed an inverse association only in the comparison with friend controls (OR=0.42; 95% CI, 0.15–1.18). The overall number of these conditions (ordinal score 0, 1, 2, 3) was inversely associated with glioma: The risk decreased 31–45% with each addition of an atopic condition. These estimates were the most stable when different control groups were considered. Comparing the prevalence of these conditions in the three control groups with published data, we note that clinic-based controls generally better approximate the prevalence data for population-based groups. These controls appear to present a reasonable choice for clinic-centered case-control studies. PMID:19336556

Maximum likelihood estimation for Cox's regression model under nested case-control sampling.

PubMed

Scheike, Thomas H; Juul, Anders

2004-04-01

Nested case-control sampling is designed to reduce the costs of large cohort studies. It is important to estimate the parameters of interest as efficiently as possible. We present a new maximum likelihood estimator (MLE) for nested case-control sampling in the context of Cox's proportional hazards model. The MLE is computed by the EM-algorithm, which is easy to implement in the proportional hazards setting. Standard errors are estimated by a numerical profile likelihood approach based on EM aided differentiation. The work was motivated by a nested case-control study that hypothesized that insulin-like growth factor I was associated with ischemic heart disease. The study was based on a population of 3784 Danes and 231 cases of ischemic heart disease where controls were matched on age and gender. We illustrate the use of the MLE for these data and show how the maximum likelihood framework can be used to obtain information additional to the relative risk estimates of covariates.

A case-control study of hormonal exposures as etiologic factors for ALS in women: Euro-MOTOR.

PubMed

Rooney, James P K; Visser, Anne E; D'Ovidio, Fabrizio; Vermeulen, Roel; Beghi, Ettore; Chio, Adriano; Veldink, Jan H; Logroscino, Giancarlo; van den Berg, Leonard H; Hardiman, Orla

2017-09-19

To investigate the role of hormonal risk factors for amyotrophic lateral sclerosis (ALS) among women from 3 European countries. ALS cases and matched controls were recruited over 4 years in Ireland, Italy, and the Netherlands. Hormonal exposures, including reproductive history, breastfeeding, contraceptive use, hormonal replacement therapy, and gynecologic surgical history, were recorded with a validated questionnaire. Logistic regression models adjusted for age, education, study site, smoking, alcohol, and physical activity were used to determine the association between female hormones and ALS risk. We included 653 patients and 1,217 controls. Oral contraceptive use was higher among controls (odds ratio [OR] 0.65, 95% confidence interval [CI] 0.51-0.84), and a dose-response effect was apparent. Hormone replacement therapy (HRT) was associated with a reduced risk of ALS only in the Netherlands (OR = 0.57, 95% CI 0.37-0.85). These findings were robust to sensitivity analysis, but there was some heterogeneity across study sites. This large case-control study across 3 different countries has demonstrated an association between exogenous estrogens and progestogens and reduced odds of ALS in women. These results are at variance with previous findings, which may be partly explained by differential regulatory, social, and cultural attitudes toward pregnancy, birth control, and HRT across the countries included. Our results indicate that hormonal factors may be important etiologic factors in ALS; however, a full understanding requires further investigation. © 2017 American Academy of Neurology.

Snippets from the past: is Flint, Michigan, the birthplace of the case-control study?

PubMed

Morabia, Alfredo

2013-12-15

In the summer of 1924, an outbreak of scarlet fever occurred in Flint, Michigan. Unable to trace it to the usual causes, particularly fresh milk, the Michigan Department of Health used a novel approach to disentangle the enigma: The 116 cases of scarlet fever were compared with 117 "controls" selected from neighbors of the quarantined cases and from patients at the City Health Center who had been treated for ailments unrelated to scarlet fever. The extraordinary culprit was ice cream, which had a frequent/occasional/none consumption prevalence of 60%, 34%, and 6% among the cases and 24%, 51%, and 25% among the controls, respectively. The 1925 report reads, "Detailed epidemiological investigation, by means of case histories and control histories on well persons, confirmed early suspicions and established the fact that the epidemic was spread by ice cream" (Am J Hyg. 1925;5(5):669-681). This forgotten epidemiologic study is the oldest study using the case-control design to have been resurrected thus far. The case-control study design may have been conceived simultaneously, but independently and for different purposes, in England (Janet Lane-Claypon's 1926 report on the determinants of breast cancer) and the United States.

Role of survivor bias in pancreatic cancer case-control studies.

PubMed

Hu, Zhen-Huan; Connett, John E; Yuan, Jian-Min; Anderson, Kristin E

2016-01-01

The purpose of this study was to evaluate the impact of survivor bias on pancreatic cancer case-control studies. The authors constructed five case-loss scenarios based on the Iowa Women's Health Study cohort to reflect how case recruitment in population-based studies varies by case survival time. Risk factors for disease incidence included smoking, body mass index (BMI), waist circumference, diabetes, and alcohol consumption. Odds ratios (ORs) were estimated by conditional logistic regression and quantitatively compared by the interactions between risk factors and 3-month survival time. Additionally, Kaplan-Meier estimates for overall survival were compared within the subset cohort of pancreatic cancer cases. BMI and waist circumference showed a significant inverse relationship with survival time. Decreasing trends in ORs for BMI and waist circumference were observed with increasing case survival time. The interaction between BMI and survival time based on a cutpoint of 3 months was significant (P < .01) as was the interaction between waist circumference and survival time (P < .01). The findings suggested that case losses could result in survivor bias causing underestimated odds ratios for both BMI and waist circumference, whereas other risk factors were not significantly affected by case losses. Copyright © 2016 Elsevier Inc. All rights reserved.

History of chickenpox in glioma risk: a report from the glioma international case-control study (GICC).

PubMed

Amirian, E Susan; Scheurer, Michael E; Zhou, Renke; Wrensch, Margaret R; Armstrong, Georgina N; Lachance, Daniel; Olson, Sara H; Lau, Ching C; Claus, Elizabeth B; Barnholtz-Sloan, Jill S; Il'yasova, Dora; Schildkraut, Joellen; Ali-Osman, Francis; Sadetzki, Siegal; Jenkins, Robert B; Bernstein, Jonine L; Merrell, Ryan T; Davis, Faith G; Lai, Rose; Shete, Sanjay; Amos, Christopher I; Melin, Beatrice S; Bondy, Melissa L

2016-06-01

Varicella zoster virus (VZV) is a neurotropic α-herpesvirus that causes chickenpox and establishes life-long latency in the cranial nerve and dorsal root ganglia of the host. To date, VZV is the only virus consistently reported to have an inverse association with glioma. The Glioma International Case-Control Study (GICC) is a large, multisite consortium with data on 4533 cases and 4171 controls collected across five countries. Here, we utilized the GICC data to confirm the previously reported associations between history of chickenpox and glioma risk in one of the largest studies to date on this topic. Using two-stage random-effects restricted maximum likelihood modeling, we found that a positive history of chickenpox was associated with a 21% lower glioma risk, adjusting for age and sex (95% confidence intervals (CI): 0.65-0.96). Furthermore, the protective effect of chickenpox was stronger for high-grade gliomas. Our study provides additional evidence that the observed protective effect of chickenpox against glioma is unlikely to be coincidental. Future studies, including meta-analyses of the literature and investigations of the potential biological mechanism, are warranted. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Social and economic impact of diabetics in Bangladesh: protocol for a case-control study.

PubMed

Shariful Islam, Sheikh Mohammed; Lechner, Andreas; Ferrari, Uta; Froeschl, Guenter; Niessen, Louis W; Seissler, Jochen; Alam, Dewan Shamsul

2013-12-21

Diabetes affects both individuals and their families and has an impact on economic and social development of a country. Information on the availability, cost, and quality of medical care for diabetes is mostly not available for many low- and middle-income countries including Bangladesh. Complications from diabetes, which can be devastating, could largely be prevented by wider use of several inexpensive generic medicines, simple tests and monitoring and can be a cost saving intervention. This study will provide an in-depth and comprehensive picture of social and economic impacts of diabetes in Bangladesh and propose clear recommendations for improving prevention and management of diabetes. The objectives of the study are: 1) To study the association between diabetes and other health problems and its social impacts. 2) To estimate the economic impact of diabetes including total direct and indirect costs. 3) To measure the impact of diabetes on quality of life among diabetes patients in Bangladesh. 4) To study the impact of diabetes on the health care system This is a case-control study comparing cases with type 2 diabetes to controls without diabetes matched on age, sex and place of residence. 564 cases and 564 controls will be selected from the outpatient department of a tertiary hospital in Dhaka, Bangladesh. Data on socioeconomic status, health utility index, direct and indirect costs for diabetes, medication adherence, quality of life, treatment satisfaction, diet, physical activity, mental state examination, weight, height, hip and waist circumference, blood pressure, pulse, medication history, laboratory data and physical examination will be conducted. The primary outcome measures will be association between diabetes and other health problems, cost of diabetes, impact of diabetes on quality of life and secondary outcome measures are impact of diabetes on healthcare systems in Bangladesh. This study will provide an in-depth and comprehensive picture of social

Lifestyle factors and risk of leukemia and non-Hodgkin's lymphoma: a case-control study.

PubMed

Parodi, Stefano; Santi, Irene; Marani, Enza; Casella, Claudia; Puppo, Antonella; Garrone, Elsa; Fontana, Vincenzo; Stagnaro, Emanuele

2016-03-01

Risk factors for leukemia and lymphomas in adults are largely unknown. This study was aimed at evaluating the association between lifestyle factors and the risk of hematological malignancies in an adult population. Data were drawn from a population-based case-control study carried out in Italy and included 294 cases (199 lymphoid and 95 myeloid) and 279 controls. Analyses were performed using standard multivariable logistic regression. Hair dye use for at least 15 years was associated with a higher risk of lymphoid malignancies among females (OR 2.3, 95 % CI 1.0-4.9, p = 0.036, test for trend). Furthermore, a protective effect of a moderate to heavy tea consumption on the risk of myeloid malignancies was observed (OR 0.4, 95 % CI 0.2-0.9, p = 0.017). No association was found for the use of alcoholic beverages and tobacco smoking. Our results confirm the potential carcinogenic effect of prolonged hair dye use observed in previous investigations. The excess risk could be explained by exposure to a higher concentration of toxic compounds in hair products used in the past. The protective effect of regular tea consumption observed in an area with a very high prevalence of black tea consumers deserves further investigation.

Genotyping and inflated type I error rate in genome-wide association case/control studies

PubMed Central

Sampson, Joshua N; Zhao, Hongyu

2009-01-01

Background One common goal of a case/control genome wide association study (GWAS) is to find SNPs associated with a disease. Traditionally, the first step in such studies is to assign a genotype to each SNP in each subject, based on a statistic summarizing fluorescence measurements. When the distributions of the summary statistics are not well separated by genotype, the act of genotype assignment can lead to more potential problems than acknowledged by the literature. Results Specifically, we show that the proportions of each called genotype need not equal the true proportions in the population, even as the number of subjects grows infinitely large. The called genotypes for two subjects need not be independent, even when their true genotypes are independent. Consequently, p-values from tests of association can be anti-conservative, even when the distributions of the summary statistic for the cases and controls are identical. To address these problems, we propose two new tests designed to reduce the inflation in the type I error rate caused by these problems. The first algorithm, logiCALL, measures call quality by fully exploring the likelihood profile of intensity measurements, and the second algorithm avoids genotyping by using a likelihood ratio statistic. Conclusion Genotyping can introduce avoidable false positives in GWAS. PMID:19236714

Toxoplasma gondii exposure and Parkinson's disease: a case-control study.

PubMed

Alvarado-Esquivel, Cosme; Méndez-Hernández, Edna Madai; Salas-Pacheco, José Manuel; Ruano-Calderón, Luis Ángel; Hernández-Tinoco, Jesús; Arias-Carrión, Oscar; Sánchez-Anguiano, Luis Francisco; Castellanos-Juárez, Francisco Xavier; Sandoval-Carrillo, Ada Agustina; Liesenfeld, Oliver; Ramos-Nevárez, Agar

2017-02-13

To determine the association between Toxoplasma gondii infection and Parkinson's disease and to investigate whether T. gondii seropositivity is associated with the general characteristics of patients with Parkinson's disease. Case-control study. Cases and controls were enrolled in Durango City, Mexico. 65 patients with Parkinson's disease and 195 age- and gender-matched control subjects without Parkinson's disease. Serum samples of participants were analysed for anti- T. gondii IgG and IgM antibodies by commercially available enzyme-linked immunoassays. Prevalence of T. gondii DNA was determined in seropositive subjects using PCR. The association between clinical data and infection was examined by bivariate analysis. Anti- T. gondii IgG antibodies were found in 6/65 cases (9.2%) and in 21/195 controls (10.8%) (OR 0.84; 95% CI 0.32 to 2.18; p=0.81). The frequency of high (>150 IU/mL) antibody levels was similar among cases and controls (p=0.34). None of the anti- T. gondii IgG positive cases and four of the anti- T. gondii IgG positive controls had anti- T. gondii IgM antibodies (p=0.54). The prevalence of T. gondii DNA was comparable in seropositive cases and controls (16.7% and 25%, respectively; p=1.0). Seroprevalence of T. gondii infection was associated with a young age onset of disease (p=0.03), high Unified Parkinson Disease Rating Scale scores (p=0.04) and depression (p=0.02). Seropositivity to T. gondii infection was lower in patients treated with pramipexole than in patients without this treatment (p=0.01). However, none of the associations remained significant after Bonferroni correction. The results do not support an association between T. gondii infection and Parkinson's disease. However, T. gondii infection might have an influence on certain symptoms of Parkinson's disease. Further research to elucidate the role of T. gondii exposure on Parkinson's disease is warranted. Published by the BMJ Publishing Group Limited. For permission to use (where not

Pretreatment Serum Concentrations of 25-Hydroxyvitamin D and Breast Cancer Prognostic Characteristics: A Case-Control and a Case-Series Study

PubMed Central

Yao, Song; Sucheston, Lara E.; Millen, Amy E.; Johnson, Candace S.; Trump, Donald L.; Nesline, Mary K.; Davis, Warren; Hong, Chi-Chen; McCann, Susan E.; Hwang, Helena; Kulkarni, Swati; Edge, Stephen B.; O'Connor, Tracey L.; Ambrosone, Christine B.

2011-01-01

Background Results from epidemiologic studies on the relationship between vitamin D and breast cancer risk are inconclusive. It is possible that vitamin D may be effective in reducing risk only of specific subtypes due to disease heterogeneity. Methods and Findings In case-control and case-series analyses, we examined serum concentrations of 25-hydroxyvitamin D (25OHD) in relation to breast cancer prognostic characteristics, including histologic grade, estrogen receptor (ER), and molecular subtypes defined by ER, progesterone receptor (PR) and HER2, among 579 women with incident breast cancer and 574 controls matched on age and time of blood draw enrolled in the Roswell Park Cancer Institute from 2003 to 2008. We found that breast cancer cases had significantly lower 25OHD concentrations than controls (adjusted mean, 22.8 versus 26.2 ng/mL, p<0.001). Among premenopausal women, 25OHD concentrations were lower in those with high- versus low-grade tumors, and ER negative versus ER positive tumors (p≤0.03). Levels were lowest among women with triple-negative cancer (17.5 ng/mL), significantly different from those with luminal A cancer (24.5 ng/mL, p = 0.002). In case-control analyses, premenopausal women with 25OHD concentrations above the median had significantly lower odds of having triple-negative cancer (OR = 0.21, 95% CI = 0.08–0.53) than those with levels below the median; and every 10 ng/mL increase in serum 25OHD concentrations was associated with a 64% lower odds of having triple-negative cancer (OR = 0.36, 95% CI = 0.22–0.56). The differential associations by tumor subtypes among premenopausal women were confirmed in case-series analyses. Conclusion In our analyses, higher serum levels of 25OHD were associated with reduced risk of breast cancer, with associations strongest for high grade, ER negative or triple negative cancers in premenopausal women. With further confirmation in large prospective studies, these findings could warrant

Effectiveness of monovalent rotavirus vaccine in Bolivia: case-control study.

PubMed

Patel, Manish M; Patzi, Maritza; Pastor, Desiree; Nina, Aleida; Roca, Yelin; Alvarez, Leovigildo; Iniguez, Volga; Rivera, Rosario; Tam, Ka Ian; Quaye, Osbourne; Bowen, Michael; Parashar, Umesh; De Oliveira, Lucia Helena

2013-06-19

To evaluate the effectiveness of two doses of a monovalent rotavirus vaccine (RV1) against hospital admission for rotavirus in Bolivia. Case-control study. Six hospitals in Bolivia, between March 2010 and June 2011. 400 hospital admissions for rotavirus, 1200 non-diarrhea hospital controls, and 718 rotavirus negative hospital controls. Odds of antecedent vaccination between case patients and controls; effectiveness of vaccination ((1-adjusted odds ratio)×100), adjusted for age and other confounders; and stratified effectiveness by dose, disease severity, age group, and serotype. In comparison with non-diarrhea controls, case patients were more likely to be male and attend day care but less likely to have chronic underlying illness, higher level maternal education, and telephones and computers in their home. Rotavirus negative controls were somewhat more similar to case patients but also were more likely to be male and attend day care and less likely to have higher level maternal education and computers in their homes. The adjusted effectiveness of RV1 against hospital admission for rotavirus was 69% (95% confidence interval 54% to 79%) with rotavirus negative controls and 77% (65% to 84%) with non-diarrhea controls. The effectiveness of one dose of RV1 was 36% and 56%, respectively. With both control groups, protection was sustained through two years of life, with similar efficacy against hospital admission among children under 1 year (64% and 77%) and over 1 year of age (72% and 76%). RV1 provided significant protection against diverse serotypes, partially and fully heterotypic to the G1P[8] vaccine. Effectiveness using the two control groups was 80% and 85% against G9P[8], 74% and 93%% against G3P[8], 59% and 69% against G2P[4], and 80% and 87% against G9P[6] strains. The monovalent rotavirus vaccine conferred high protection against hospital admission for diarrhea due to rotavirus in Bolivian children. Protection was sustained through two years of life against

Case-control study on the prevention of occupational eye injuries.

PubMed

Ho, Chi-Kung; Yen, Ya-Lin; Chang, Cheng-Hsien; Chiang, Hung-Che; Shen, Ying-Ying; Chang, Po-Ya

2008-01-01

The risk factors for occupational eye injuries have never been published in Taiwan. We conducted a case-control study to analyze the differences among workers on their knowledge, attitude to and practice (KAP) of occupational accident prevention. In the study, a statistical model was also set up for predicting the occupational problem. Subjects, including 31 cases of work-related eye injuries and 62 controls, completed a structured questionnaire on KAP, which revealed that 80.6% and 62.7% of workers in the case and control groups, respectively, did not wear eye protection during work. Furthermore, we found that temporary employment (OR, 10.7; 95% CI, 3.03-36.16) and fewer than 10 years of education (OR, 4.44; 95% CI, 1.73-11.44) were the major risk factors for occupational eye injuries. In addition, we developed a logistic regression model with four predictors (temporary employment, education years less than 10, poor management of industrial health and safety in the workplace, and poor attitude towards accident prevention) for the occurrence of occupational eye injuries. In conclusion, in Taiwan, compulsory regulation of wearing eye protection during work, good education, management of work safety and hygiene and employee (especially temporary worker) commitment to safety and health are strongly recommended prevention strategies.

Case studies of power and control related to tobacco use during pregnancy.

PubMed

Greaves, Lorraine; Kalaw, Cecilia; Bottorff, Joan L

2007-01-01

The objective was to identify and describe elements of power and control evident in couple tobacco-related interaction patterns during pregnancy. Using a case study approach, elements of the Duluth Abuse Intervention Project Power and Control Wheel were used to examine women's experiences of tobacco reduction during pregnancy and post partum. Three cases were selected from a larger qualitative sample, using a maximum variation sampling approach. Although no direct evidence of partner abuse or violence accompanying partner efforts to influence women's smoking was described, most of the elements of power and control were present in the case study, and appeared to cause an emotional toll and a negative impact on women's ability to freely express their views about their own tobacco use. Elements of power and control, however subtle, are potentially important and unrecognized dimensions of women's tobacco reduction experiences. Additional care and attention should be taken in designing tobacco reduction interventions and policies directed at pregnant and post partum women and their partners to reduce the possibility that these interventions may contribute to the use of power and control.

The Consequences of Metric Production for Small Manufacturers. Volume II. Case Studies of Large Business-Small Business Interaction,

DTIC Science & Technology

1982-02-08

II 00 CASE STUDIES OF LARGE BUSINESS - SMALL BUSINESS INTERACTION ’C- DTIC. Henry H1. Hitchcock dlELECTE7 Joseph F. Coates Marcy M. Canavan AUGG261982...J wis&omWWS1ARET N W WASIINGTOW. OC NO$I THE CONSEQUENCES OF METRIC PRODUCTION FOR SMALL MANUFACTURERS Volume 11 CASE STUDIES OF LARGE BUSINESS ... SMALL BUSINESS INTERACTION Accesqi~r, For NTIS GRA&t DTIC TAB Unannoun~ced J’htiI’ctof _ Henry H. Hitchcock vi 1ribr i t o aes Joseph F. Coates Avail arid

Adaptation of Chain Event Graphs for use with Case-Control Studies in Epidemiology.

PubMed

Keeble, Claire; Thwaites, Peter Adam; Barber, Stuart; Law, Graham Richard; Baxter, Paul David

2017-09-26

Case-control studies are used in epidemiology to try to uncover the causes of diseases, but are a retrospective study design known to suffer from non-participation and recall bias, which may explain their decreased popularity in recent years. Traditional analyses report usually only the odds ratio for given exposures and the binary disease status. Chain event graphs are a graphical representation of a statistical model derived from event trees which have been developed in artificial intelligence and statistics, and only recently introduced to the epidemiology literature. They are a modern Bayesian technique which enable prior knowledge to be incorporated into the data analysis using the agglomerative hierarchical clustering algorithm, used to form a suitable chain event graph. Additionally, they can account for missing data and be used to explore missingness mechanisms. Here we adapt the chain event graph framework to suit scenarios often encountered in case-control studies, to strengthen this study design which is time and financially efficient. We demonstrate eight adaptations to the graphs, which consist of two suitable for full case-control study analysis, four which can be used in interim analyses to explore biases, and two which aim to improve the ease and accuracy of analyses. The adaptations are illustrated with complete, reproducible, fully-interpreted examples, including the event tree and chain event graph. Chain event graphs are used here for the first time to summarise non-participation, data collection techniques, data reliability, and disease severity in case-control studies. We demonstrate how these features of a case-control study can be incorporated into the analysis to provide further insight, which can help to identify potential biases and lead to more accurate study results.

Case-control study of childhood acute lymphoblastic leukemia and residential radon exposure.

PubMed

Lubin, J H; Linet, M S; Boice, J D; Buckley, J; Conrath, S M; Hatch, E E; Kleinerman, R A; Tarone, R E; Wacholder, S; Robison, L L

1998-02-18

Several ecologic analyses have shown significant positive associations between mean indoor radon concentrations and risk of leukemia at all ages (acute myeloid leukemia and chronic lymphocytic leukemia) and for children (all leukemia, acute myeloid leukemia, and acute lymphoblastic leukemia [ALL]). As part of an age-matched, case-control study of childhood ALL in the United States, we investigated the association between the incidence of ALL in children under age 15 years and indoor radon exposure. Radon detectors were placed in current and previous homes of subjects where they resided for 6 months or longer. Children were included in analyses if radon measurements covered 70% or more of the 5-year period prior to diagnosis for case subjects (or from birth for case subjects under age 5 years) and the corresponding reference dates for control subjects. Radon levels could be estimated for 97% of the exposure period for the eligible 505 case subjects and 443 control subjects. Mean radon concentration was lower for case subjects (65.4 becquerels per cubic meter [Bqm(-3)]) than for control subjects (79.1 Bqm(-3)). For categories less than 37, 37-73, 74-147, and 148 or more Bqm(-3) of radon exposure, relative risks based on matched case-control pairs were 1.00, 1.22, 0.82, and 1.02, respectively, and were similar to results from an unmatched analysis. There was no association between ALL and radon exposure within subgroups defined by categories of age, income, birth order, birth weight, sex, type of residence, magnetic field exposure, parental age at the subject's birth, parental occupation, or parental smoking habits. In contrast to prior ecologic studies, the results from this analytic study provide no evidence for an association between indoor radon exposure and childhood ALL.

Leucocytes telomere length and breast cancer risk/ susceptibility: A case-control study.

PubMed

Pavanello, Sofia; Varesco, Liliana; Gismondi, Viviana; Bruzzi, Paolo; Bolognesi, Claudia

2018-01-01

Telomere length in peripheral blood leukocytes (PBL-TL) was proposed as a biomarker of cancer risk. Recent scientific evidence suggested PBL-TL plays a diverse role in different cancers. Inconsistent results were obtained on PBL-TL in relation to breast cancer risk and specifically to the presence of BRCA1 and BRCA2 mutations. The aim of the present case-control study was to analyse the correlation between family history of breast cancer or presence of a BRCA mutation and PBL-TL in the hypothesis that TL is a modifier of cancer risk. PBL-TL was measured using the real-time quantitative PCR method in DNA for 142 cases and 239 controls. All the women enrolled were characterized for cancer family history. A subgroup of 48 women were classified for the presence of a BRCA mutation. PBL-TL were summarized as means and standard deviations, and compared by standard analysis of variance. A multivariable Generalised Linear Model was fitted to the data with PBL-TL as the dependent variable, case/control status and presence of a BRCA/VUS mutation as factors, and age in 4 strata as a covariate. Age was significantly associated with decreasing PBL-TL in controls (p = 0.01), but not in BC cases. The telomere length is shorter in cases than in controls after adjusting for age. No effect on PBL-TL of BMI, smoke nor of the most common risk factors for breast cancer was observed. No association between PBL-TL and family history was detected both in BC cases and controls. In the multivariate model, no association was observed between BRCA mutation and decreased PBL-TL. A statistically significant interaction (p = 0.031) between case-control status and a BRCA-mutation/VUS was observed, but no effect was detected for the interaction of cancer status and BRCA or VUS. Our study fails to provide support to the hypothesis that PBL-TL is associated with the risk of hereditary BC, or that is a marker of inherited mutations in BRCA genes.

Leucocytes telomere length and breast cancer risk/ susceptibility: A case-control study

PubMed Central

Pavanello, Sofia; Varesco, Liliana; Gismondi, Viviana; Bruzzi, Paolo

2018-01-01

Background Telomere length in peripheral blood leukocytes (PBL-TL) was proposed as a biomarker of cancer risk. Recent scientific evidence suggested PBL-TL plays a diverse role in different cancers. Inconsistent results were obtained on PBL-TL in relation to breast cancer risk and specifically to the presence of BRCA1 and BRCA2 mutations. The aim of the present case-control study was to analyse the correlation between family history of breast cancer or presence of a BRCA mutation and PBL-TL in the hypothesis that TL is a modifier of cancer risk. Methods PBL-TL was measured using the real-time quantitative PCR method in DNA for 142 cases and 239 controls. All the women enrolled were characterized for cancer family history. A subgroup of 48 women were classified for the presence of a BRCA mutation. PBL-TL were summarized as means and standard deviations, and compared by standard analysis of variance. A multivariable Generalised Linear Model was fitted to the data with PBL-TL as the dependent variable, case/control status and presence of a BRCA/VUS mutation as factors, and age in 4 strata as a covariate. Results Age was significantly associated with decreasing PBL-TL in controls (p = 0.01), but not in BC cases. The telomere length is shorter in cases than in controls after adjusting for age. No effect on PBL-TL of BMI, smoke nor of the most common risk factors for breast cancer was observed. No association between PBL-TL and family history was detected both in BC cases and controls. In the multivariate model, no association was observed between BRCA mutation and decreased PBL-TL. A statistically significant interaction (p = 0.031) between case-control status and a BRCA-mutation/VUS was observed, but no effect was detected for the interaction of cancer status and BRCA or VUS. Conclusion Our study fails to provide support to the hypothesis that PBL-TL is associated with the risk of hereditary BC, or that is a marker of inherited mutations in BRCA genes. PMID:29782524

Occupation and malignant lymphoma: a population based case control study in Germany

PubMed Central

Mester, B; Nieters, A; Deeg, E; Elsner, G; Becker, N; Seidler, A

2006-01-01

Aims To identify occupations suspected to be associated with malignant lymphoma and to generate new hypotheses about occupational risks in a multicentre, population based case control study. Methods Male and female patients with malignant lymphoma (n = 710) aged 18–80 years of age were prospectively recruited in six study regions in Germany. For each newly recruited lymphoma case, a sex, region, and age matched control was drawn from the population registers. Odds ratios and 95% confidence intervals for major occupations and industries were calculated using conditional logistic regression analysis, adjusted for smoking (in pack‐years) and alcohol consumption. Patients with specific lymphoma subentities were additionally compared with the entire control group using unconditional logistic regression analysis. Results The following economic/industrial sectors were positively associated with lymphoma: food products, beverages, tobacco; paper products, publishing and printing; and metals. Chemicals; real estate, renting, and business activities were negatively associated with lymphoma diagnosis. The authors observed an increased overall lymphoma risk among architects; maids; farmers; glass formers; and construction workers. Shoemaking and leather goods making was negatively associated with the lymphoma diagnosis (although based on small numbers). In the occupational group analysis of lymphoma subentities, Hodgkin's lymphoma was significantly associated only with rubber and plastic products making; diffuse large B cell lymphoma risk was considerably increased among metal processors; follicular lymphoma showed highly significant risk increases for several occupational groups (medical, dental, and veterinary workers; sales workers; machinery fitters; and electrical fitters); and multiple myeloma showed a particularly pronounced risk increase for farmers as well as for agriculture and animal husbandry workers. Conclusions The results partly confirm previously

Reengagement in PTSD psychotherapy: A case-control study.

PubMed

Buchholz, Katherine R; Bohnert, Kipling M; Pfeiffer, Paul N; Valenstein, Marcia; Ganoczy, Dara; Anderson, RaeAnn E; Sripada, Rebecca K

2017-09-01

This study sought to identify patient characteristics and care processes related to reengagement in VA psychotherapy. Using national VA data, a retrospective cohort was constructed (N=24,492) of veterans who received a new PTSD diagnosis in FY08/FY09 and attended only one to five PTSD psychotherapy sessions. A nested case-control study was conducted comparing veterans who reengaged in psychotherapy (n=9649) in a 1:5 ratio with those who did not reengage by the end of FY12. Conditional logistic regression models were run to examine differences in sociodemographic, mental health, and service utilization factors between cases and controls. Among veterans in the study cohort, 39.4% reengaged in psychotherapy. In adjusted analyses, all measured types of health system encounters (primary care [OR=1.61], primary care mental health [OR=1.61], non-PTSD psychotherapy [OR=1.76], other non-PTSD mental health care [OR=1.43], other non-psychotherapy PTSD care [OR=3.31], emergency room [OR=1.14], and psychiatric hospitalization [OR=1.56]) were related to greater odds of reengagement in PTSD psychotherapy. Veterans' receipt of a broad range of care services may play an important role in reengagement in PCT psychotherapy, suggesting providers across care settings should be knowledgeable in how to support a Veteran's return to psychotherapy for PTSD. Published by Elsevier Inc.

Trachoma and Relative Poverty: A Case-Control Study

PubMed Central

Habtamu, Esmael; Wondie, Tariku; Aweke, Sintayehu; Tadesse, Zerihun; Zerihun, Mulat; Zewdie, Zebideru; Callahan, Kelly; Emerson, Paul M.; Kuper, Hannah; Bailey, Robin L.; Mabey, David C. W.; Rajak, Saul N.; Polack, Sarah; Weiss, Helen A.; Burton, Matthew J.

2015-01-01

Background Trachoma is widely considered a disease of poverty. Although there are many epidemiological studies linking trachoma to factors normally associated with poverty, formal quantitative data linking trachoma to household economic poverty within endemic communities is very limited. Methodology/Principal Findings Two hundred people with trachomatous trichiasis were recruited through community-based screening in Amhara Region, Ethiopia. These were individually matched by age and gender to 200 controls without trichiasis, selected randomly from the same sub-village as the case. Household economic poverty was measured through (a) A broad set of asset-based wealth indicators and relative household economic poverty determined by principal component analysis (PCA, (b) Self-rated wealth, and (c) Peer-rated wealth. Activity participation data were collected using a modified ‘Stylised Activity List’ developed for the World Bank’s Living Standards Measurement Survey. Trichiasis cases were more likely to belong to poorer households by all measures: asset-based analysis (OR = 2.79; 95%CI: 2.06–3.78; p<0.0001), self-rated wealth (OR, 4.41, 95%CI, 2.75–7.07; p<0.0001) and peer-rated wealth (OR, 8.22, 95% CI, 4.59–14.72; p<0.0001). Cases had less access to latrines (57% v 76.5%, p = <0.0001) and higher person-to-room density (4.0 v 3.31; P = 0.0204) than the controls. Compared to controls, cases were significantly less likely to participate in economically productive activities regardless of visual impairment and other health problems, more likely to report difficulty in performing activities and more likely to receive assistance in performing productive activities. Conclusions/Significance This study demonstrated a strong association between trachomatous trichiasis and relative poverty, suggesting a bidirectional causative relationship possibly may exist between poverty and trachoma. Implementation of the full SAFE strategy in the context of general improvements

Investigation of established genetic risk variants for glioma in prediagnostic samples from a population-based nested case-control study.

PubMed

Wibom, Carl; Späth, Florentin; Dahlin, Anna M; Langseth, Hilde; Hovig, Eivind; Rajaraman, Preetha; Johannesen, Tom Børge; Andersson, Ulrika; Melin, Beatrice

2015-05-01

Although glioma etiology is poorly understood in general, growing evidence indicates a genetic component. Four large genome-wide association studies (GWAS) have linked common genetic variants with an increased glioma risk. However, to date, these studies are based largely on a case-control design, where cases have been recruited at the time of or after diagnosis. They may therefore suffer from a degree of survival bias, introduced when rapidly fatal cases are not included. To confirm glioma risk variants in a prospective setting, we have analyzed 11 previously identified risk variants in a set of prediagnostic serum samples with 598 cases and 595 matched controls. Serum samples were acquired from The Janus Serum Bank, a Norwegian population-based biobank reserved for cancer research. We confirmed the association with glioma risk for variants within five genomic regions: 8q24.21 (CCDC26), 9p21.3 (CDKN2B-AS1), 11q23.3 (PHLDB1), 17p13.1 (TP53), and 20q13.33 (RTEL1). However, previously identified risk variants within the 7p11.2 (EGFR) region were not confirmed by this study. Our results indicate that the risk variants that were confirmed by this study are truly associated with glioma risk and may, consequently, affect gliomagenesis. Though the lack of positive confirmation of EGFR risk variants may be attributable to relatively limited statistical power, it nevertheless raises the question whether they truly are risk variants or markers for glioma prognosis. Our findings indicate the need for further studies to clarify the role of glioma risk loci with respect to prolonged survival versus etiology. ©2015 American Association for Cancer Research.

Comparison of two control groups for estimation of oral cholera vaccine effectiveness using a case-control study design.

PubMed

Franke, Molly F; Jerome, J Gregory; Matias, Wilfredo R; Ternier, Ralph; Hilaire, Isabelle J; Harris, Jason B; Ivers, Louise C

2017-10-13

Case-control studies to quantify oral cholera vaccine effectiveness (VE) often rely on neighbors without diarrhea as community controls. Test-negative controls can be easily recruited and may minimize bias due to differential health-seeking behavior and recall. We compared VE estimates derived from community and test-negative controls and conducted bias-indicator analyses to assess potential bias with community controls. From October 2012 through November 2016, patients with acute watery diarrhea were recruited from cholera treatment centers in rural Haiti. Cholera cases had a positive stool culture. Non-cholera diarrhea cases (test-negative controls and non-cholera diarrhea cases for bias-indicator analyses) had a negative culture and rapid test. Up to four community controls were matched to diarrhea cases by age group, time, and neighborhood. Primary analyses included 181 cholera cases, 157 non-cholera diarrhea cases, 716 VE community controls and 625 bias-indicator community controls. VE for self-reported vaccination with two doses was consistent across the two control groups, with statistically significant VE estimates ranging from 72 to 74%. Sensitivity analyses revealed similar, though somewhat attenuated estimates for self-reported two dose VE. Bias-indicator estimates were consistently less than one, with VE estimates ranging from 19 to 43%, some of which were statistically significant. OCV estimates from case-control analyses using community and test-negative controls were similar. While bias-indicator analyses suggested possible over-estimation of VE estimates using community controls, test-negative analyses suggested this bias, if present, was minimal. Test-negative controls can be a valid low-cost and time-efficient alternative to community controls for OCV effectiveness estimation and may be especially relevant in emergency situations. Copyright © 2017. Published by Elsevier Ltd.

Diarrheagenic Escherichia coli and Acute Gastroenteritis in Children in Davidson County, Tennessee, United States: A Case-control Study.

PubMed

Imdad, Aamer; Foster, Monique A; Iqbal, Junaid; Fonnesbeck, Christopher; Payne, Daniel C; Zhang, Chengxian; Chappell, James D; Halasa, Natasha; Gómez-Duarte, Oscar G

2018-06-01

Diarrheagenic Escherichia coli (DEC) is an important cause of acute gastroenteritis in children; however, there is limited information available on the epidemiology, phylogenetics, serotyping and antibiotic susceptibility of DEC in children in the United States. The aim of this study was to determine the molecular epidemiology of DEC among children with and without acute gastroenteritis in Davidson County, Tennessee. This prospective, frequency matched, case-control study recruited subjects 15 days to 17 years of age and detected DEC with polymerase chain reaction from stool samples. Additional testing was done to define phylogenetics and antibiotics resistance. Among 1267 participants, 857 cases and 410 controls, 5.5% were positive for at least one subtype of DEC. Enteroaggregative E. coli [n = 32 (45%)] was the most common subtype followed by enteropathogenic E. coli (EPEC) [n = 30 (43%)], Shiga toxin-producing E. coli [n = 4 (6%)] and diffusely adherent E. coli [n = 4 (6%)]. No significant difference in prevalence of DEC was found between cases (5%) and controls (7%) [odds ratio: 0.66 (95% confidence interval: 0.4-1.07)], and results were similar when data were stratified by subtypes and adjusted for age, sex, race and ethnicity. Substantial diversity was found among DEC isolates in terms of phylotypes and serotypes, and a large proportion was resistant to, at least, one antibiotic. Enteroaggregative E. coli and enteropathogenic E. coli were frequently found in both cases and controls in this study population. DNA-based methods for detection of these subtypes need further investigation to help differentiate between pathogenic and colonizing strains.

A case control study of senile cataract in a hospital based population.

PubMed

Badrinath, S S; Sharma, T; Biswas, J; Srinivas, V

1996-12-01

A case-control study (244 cases and 264 controls) was done during 1986-89 on a hospital based population to evaluate the risk factors associated with the etiology of senile cataract. Patient with age between 40-60 years, visual acuity of 6/9 or less, and presence of lenticular opacity of senile origin were included as cases. Age matched individuals with absence of lenticular opacity made up the controls. Multivariate logistic regression analysis revealed that higher systolic BP and number of meals were significantly (P < or = 0.05) associated with presence of senile cataract; whereas higher weight, education and income, and utilization of cooking water had a significant protective effect against senile cataract. The present study helps the clinician to understand the possible risk factors associated with the development of senile cataract and could be helpful in designing a intervention strategy in future.

Association between statin therapy and tendon rupture: a case-control study.

PubMed

Beri, Abhimanyu; Dwamena, Francesca C; Dwamena, Ben A

2009-05-01

Although case reports of a possible association between statin therapy and tendon rupture have been published, no analytical studies exploring this relationship have been reported. We conducted a case-control study using the electronic medical records at Michigan State University from 2002 to 2007 to assess whether statin use is a risk factor for tendon rupture. We compared exposure to statins in 93 cases of tendon rupture with similar exposure in 279 sex- and age-matched controls. Exposure to statins was defined as documentation in the electronic medical record of statin use in the 12 months preceding tendon rupture. For controls, the exposure period was defined as 1 year preceding the last office visit. We used a multivariate logistic regression model, controlling for diabetes, renal disease, rheumatologic disease, and steroid use, to calculate the adjusted odds ratios (ORs). There was no significant difference between cases and controls in the rates of statin use, with either univariate [OR = 1.0, 95% confidence interval (CI) 0.54-1.84] or multivariate analyses (OR = 1.10, 95% CI 0.57-2.13). Based on predetermined subgroup analyses, statin exposure was found to be a significant risk factor for tendon rupture in women (adjusted OR = 3.76, 95% CI 1.11-12.75) but not in men (adjusted OR = 0.66, 95% CI 0.29-1.51). In conclusion, we found no overall association between statin use and tendon rupture, but subgroup analysis suggested that women with tendon rupture were more likely to be on statins.

Tooth eruption sequence and dental crowding: a case-control study

PubMed Central

Moshkelgosha, Vahid; Khosravifard, Negar; Golkari, Ali

2014-01-01

When cases of dental crowding are identified and diagnosed promptly, interceptive orthodontics is particularly successful. Aim: To assess the differences in the eruption sequence of the mandibular canine and first premolar teeth in children with and without dental crowding. Materials and Methods: Children who attended the Shiraz Dental School's orthodontic clinic (Iran) from September to December 2012 were enrolled in this case-control study. Tooth size arch length discrepancy (TSALD) of all 8-10 year olds was calculated from patients’ dental models. Thirty-six children were randomly selected from those with TSALD of equal or less than 4mm (those with crowding). Each selected case was matched for sex and age with another child (as control) with TSALD>−4mm attending the same clinic, in the same time period. The existing panoramic radiographs were traced and the eruption percentages were measured for mandibular canine and first premolar teeth. The mean difference between canine and first premolar eruption percentages was compared between the case and control groups using the SPSS (version PASW 18) software and a paired sample t-test. Results: Canine and first premolar eruption percentages in the case group were 65.82±13.00 and 78.92±10.15 percent, respectively. The mean eruption percentages for canines and first premolars of the control group were 74.12±14.55 and 75.47±11.60 percent, respectively. There was a significant difference in pre-eruptive positions of canine and first premolar teeth in those with moderate to severe crowding when compared to the control group (p<0.001). Conclusion: These findings may improve the early diagnosis of children with high risk of developing moderate to severe crowding during mixed dentition. PMID:25110582

High risk human papillomavirus in the periodontium : A case control study.

PubMed

Shipilova, Anna; Dayakar, Manjunath Mundoor; Gupta, Dinesh

2017-01-01

Human papilloma viruses (HPVs) are small DNA viruses that have been identified in periodontal pocket as well as gingival sulcus. High risk HPVs are also associated with a subset of head and neck carcinomas. It is thought that the periodontium could be a reservoir for HPV. 1. Detection of Human Papilloma virus (HPV) in periodontal pocket as well as gingival of patients having localized chronic periodontitis and gingival sulcus of periodontally healthy subjects. 2. Quantitative estimation of E6 and E7 mRNA in subjects showing presence of HPV3. To assess whether periodontal pocket is a reservoir for HPV. This case-control study included 30 subjects with localized chronic Periodontitis (cases) and 30 periodontally healthy subjects (controls). Two samples were taken from cases, one from periodontal pocket and one from gingival sulcus and one sample was taken from controls. Samples were collected in the form of pocket scrapings and gingival sulcus scrapings from cases and controls respectively. These samples were sent in storage media for identification and estimation of E6/E7 mRNA of HPV using in situ hybridization and flow cytometry. Statistical analysis was done by using, mean, percentage and Chi Square test. A statistical package SPSS version 13.0 was used to analyze the data. P value < 0.05 was considered as statistically significant. pocket samples as well as sulcus samples for both cases and controls were found to contain HPV E6/E7 mRNAInterpretation and. Presence of HPV E6/E7 mRNA in periodontium supports the hypothesis that periodontal tissues serve as a reservoir for latent HPV and there may be a synergy between oral cancer, periodontitis and HPV. However prospective studies are required to further explore this link.

Sphingolipid metabolism potential in fecal microbiome and bronchiolitis in infants: a case-control study.

PubMed

Hasegawa, Kohei; Stewart, Christopher J; Mansbach, Jonathan M; Linnemann, Rachel W; Ajami, Nadim J; Petrosino, Joseph F; Camargo, Carlos A

2017-07-26

Emerging evidence demonstrated that the structure of fecal microbiome is associated with the likelihood of bronchiolitis in infants. However, no study has examined functional profiles of fecal microbiome in infants with bronchiolitis. In this context, we conducted a case-control study. As a part of multicenter prospective study, we collected stool samples from 40 infants hospitalized with bronchiolitis (cases). We concurrently enrolled 115 age-matched healthy controls. First, by applying 16S rRNA gene sequencing to these 155 fecal samples, we identified the taxonomic profiles of fecal microbiome. Next, based on the taxonomy data, we inferred the functional capabilities of fecal microbiome and tested for differences in the functional capabilities between cases and controls. Overall, the median age was 3 months and 45% were female. Among 274 metabolic pathways surveyed, there were significant differences between bronchiolitis cases and healthy controls for 37 pathways, including lipid metabolic pathways (false discovery rate [FDR] <0.05). Particularly, the fecal microbiome of bronchiolitis cases had consistently higher abundances of gene function related to the sphingolipid metabolic pathways compared to that of controls (FDR <0.05). These pathways were more abundant in infants with Bacteroides-dominant microbiome profile compared to the others (FDR <0.001). On the basis of the predicted metagenome in this case-control study, we found significant differences in the functional potential of fecal microbiome between infants with bronchiolitis and healthy controls. Although causal inferences remain premature, our data suggest a potential link between the bacteria-derived metabolites, modulations of host immune response, and development of bronchiolitis.

Exposure to genocide and risk of suicide in Rwanda: a population-based case-control study.

PubMed

Rubanzana, Wilson; Hedt-Gauthier, Bethany L; Ntaganira, Joseph; Freeman, Michael D

2015-02-01

In Rwanda, an estimated one million people were killed during the 1994 genocide, leaving the country shattered and social fabric destroyed. Large-scale traumatic events such as wars and genocides have been linked to endemic post-traumatic stress disorder, depression and suicidality. The study objective was to investigate whether the 1994 genocide exposure is associated with suicide in Rwanda. We conducted a population-based case-control study. Suicide victims were matched to three living controls for sex, age and residential location. Exposure was defined as being a genocide survivor, having suffered physical/sexual abuse in the genocide, losing a first-degree relative in the genocide, having been convicted for genocide crimes or having a first-degree relative convicted for genocide. From May 2011 to May 2013, 162 cases and 486 controls were enrolled countrywide. Information was collected from the police, local village administrators and family members. After adjusting for potential confounders, having been convicted for genocide crimes was a significant predictor for suicide (OR=17.3, 95% CI 3.4 to 88.1). Being a survivor, having been physically or sexually abused during the genocide, and having lost a first-degree family member to genocide were not significantly associated with suicide. These findings demonstrate that individuals convicted for genocide crimes are experiencing continued psychological disturbances that affect their social reintegration into the community even 20 years after the event. Given the large number of genocide perpetrators reintegrated after criminal courts and Gacaca traditional reconciling trials, suicide could become a serious public health burden if preventive remedial action is not identified. 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.

Space-Time Analysis of Testicular Cancer Clusters Using Residential Histories: A Case-Control Study in Denmark

PubMed Central

Sloan, Chantel D.; Nordsborg, Rikke B.; Jacquez, Geoffrey M.; Raaschou-Nielsen, Ole; Meliker, Jaymie R.

2015-01-01

Though the etiology is largely unknown, testicular cancer incidence has seen recent significant increases in northern Europe and throughout many Western regions. The most common cancer in males under age 40, age period cohort models have posited exposures in the in utero environment or in early childhood as possible causes of increased risk of testicular cancer. Some of these factors may be tied to geography through being associated with behavioral, cultural, sociodemographic or built environment characteristics. If so, this could result in detectable geographic clusters of cases that could lead to hypotheses regarding environmental targets for intervention. Given a latency period between exposure to an environmental carcinogen and testicular cancer diagnosis, mobility histories are beneficial for spatial cluster analyses. Nearest-neighbor based Q-statistics allow for the incorporation of changes in residency in spatial disease cluster detection. Using these methods, a space-time cluster analysis was conducted on a population-wide case-control population selected from the Danish Cancer Registry with mobility histories since 1971 extracted from the Danish Civil Registration System. Cases (N=3297) were diagnosed between 1991 and 2003, and two sets of controls (N=3297 for each set) matched on sex and date of birth were included in the study. We also examined spatial patterns in maternal residential history for those cases and controls born in 1971 or later (N= 589 case-control pairs). Several small clusters were detected when aligning individuals by year prior to diagnosis, age at diagnosis and calendar year of diagnosis. However, the largest of these clusters contained only 2 statistically significant individuals at their center, and were not replicated in SaTScan spatial-only analyses which are less susceptible to multiple testing bias. We found little evidence of local clusters in residential histories of testicular cancer cases in this Danish population. PMID

Space-time analysis of testicular cancer clusters using residential histories: a case-control study in Denmark.

PubMed

Sloan, Chantel D; Nordsborg, Rikke B; Jacquez, Geoffrey M; Raaschou-Nielsen, Ole; Meliker, Jaymie R

2015-01-01

Though the etiology is largely unknown, testicular cancer incidence has seen recent significant increases in northern Europe and throughout many Western regions. The most common cancer in males under age 40, age period cohort models have posited exposures in the in utero environment or in early childhood as possible causes of increased risk of testicular cancer. Some of these factors may be tied to geography through being associated with behavioral, cultural, sociodemographic or built environment characteristics. If so, this could result in detectable geographic clusters of cases that could lead to hypotheses regarding environmental targets for intervention. Given a latency period between exposure to an environmental carcinogen and testicular cancer diagnosis, mobility histories are beneficial for spatial cluster analyses. Nearest-neighbor based Q-statistics allow for the incorporation of changes in residency in spatial disease cluster detection. Using these methods, a space-time cluster analysis was conducted on a population-wide case-control population selected from the Danish Cancer Registry with mobility histories since 1971 extracted from the Danish Civil Registration System. Cases (N=3297) were diagnosed between 1991 and 2003, and two sets of controls (N=3297 for each set) matched on sex and date of birth were included in the study. We also examined spatial patterns in maternal residential history for those cases and controls born in 1971 or later (N= 589 case-control pairs). Several small clusters were detected when aligning individuals by year prior to diagnosis, age at diagnosis and calendar year of diagnosis. However, the largest of these clusters contained only 2 statistically significant individuals at their center, and were not replicated in SaTScan spatial-only analyses which are less susceptible to multiple testing bias. We found little evidence of local clusters in residential histories of testicular cancer cases in this Danish population.

Co-Prevalence of Tremor with Spasmodic Dysphonia: A Case-Control Study

PubMed Central

White, Laura; Klein, Adam; Hapner, Edie; Delgaudio, John; Hanfelt, John; Jinnah, H. A.; Johns, Michael

2011-01-01

OBJECTIVES/HYPOTHESIS The aim of this study was to define the co-prevalence of tremor with spasmodic dysphonia (SD). STUDY DESIGN A single institution prospective, case-control study was performed from May 2010 to July 2010. METHODS Consecutive patients with SD (cases) and other voice disorders (controls) were enrolled prospectively. Each participant underwent a voice evaluation and an evaluation for tremor. RESULTS 146 voice disorder controls and 128 patients with SD were enrolled. 26% of patients with SD had vocal tremor, 21% had non-vocal tremor. Patients with SD were 2.8 times more likely to have co-prevalent tremor than the control group (OR = 2.81; 95% CI, 1.55 to 5.08) and only 35% of patients with SD had been seen by a neurologist for the evaluation of dystonia and tremor. CONCLUSIONS Tremor is highly prevalent in patients with SD. It is important for each patient diagnosed with SD to undergo an evaluation for tremor, this is especially important in patients diagnosed with vocal tremor. Level of evidence 3b. PMID:21792965

Maté drinking and esophageal squamous cell carcinoma in South America: pooled results from two large multicenter case-control studies.

PubMed

Lubin, Jay H; De Stefani, Eduardo; Abnet, Christian C; Acosta, Gisele; Boffetta, Paolo; Victora, Cesar; Graubard, Barry I; Muñoz, Nubia; Deneo-Pellegrini, Hugo; Franceschi, Silvia; Castellsagué, Xavier; Ronco, Alvaro L; Dawsey, Sanford M

2014-01-01

Maté tea is a nonalcoholic infusion widely consumed in southern South America, and may increase risk of esophageal squamous cell carcinoma (ESCC) and other cancers due to polycyclic aromatic hydrocarbons (PAH) and/or thermal injury. We pooled two case-control studies: a 1988 to 2005 Uruguay study and a 1986 to 1992 multinational study in Argentina, Brazil, Paraguay, and Uruguay, including 1,400 cases and 3,229 controls. We computed ORs and fitted a linear excess OR (EOR) model for cumulative maté consumption in liters/day-year (LPDY). The adjusted OR for ESCC with 95% confidence interval (CI) by ever compared with never use of maté was 1.60 (1.2-2.2). ORs increased linearly with LPDY (test of nonlinearity; P = 0.69). The estimate of slope (EOR/LPDY) was 0.009 (0.005-0.014) and did not vary with daily intake, indicating maté intensity did not influence the strength of association. EOR/LPDY estimates for consumption at warm, hot, and very hot beverage temperatures were 0.004 (-0.002-0.013), 0.007 (0.003-0.013), and 0.016 (0.009-0.027), respectively, and differed significantly (P < 0.01). EOR/LPDY estimates were increased in younger (<65) individuals and never alcohol drinkers, but these evaluations were post hoc, and were homogeneous by sex. ORs for ESCC increased linearly with cumulative maté consumption and were unrelated to intensity, so greater daily consumption for shorter duration or lesser daily consumption for longer duration resulted in comparable ORs. The strength of association increased with higher maté temperatures. Increased understanding of cancer risks with maté consumption enhances the understanding of the public health consequences given its purported health benefits.

Can iridology detect susceptibility to cancer? A prospective case-controlled study.

PubMed

Münstedt, Karsten; El-Safadi, Samer; Brück, Friedel; Zygmunt, Marek; Hackethal, Andreas; Tinneberg, Hans-Rudolf

2005-06-01

This prospective case-control study aimed to investigate the value of iridology as a diagnostic tool in detecting some common cancers. One hundred ten (110) subjects were enrolled in the study: 68 subjects had histologically proven cancers of the breast, ovary, uterus, prostate, or colorectum, and 42 were control subjects. All subjects were examined by an experienced practitioner of iridology, who was unaware of their gender or medical details. He was allowed to suggest up to five diagnoses for each subject and his results were then compared with each subject's medical diagnosis to determine the accuracy of iridology in detecting malignancy. Iridology identified the correct diagnosis in only 3 cases (sensitivity, 0.04). Iridology was of no value in diagnosing the cancers investigated in this study.

The Upper Midwest Health Study: industry and occupation of glioma cases and controls.

PubMed

Ruder, Avima M; Waters, Martha A; Carreón, Tania; Butler, Mary A; Calvert, Geoffrey M; Davis-King, Karen E; Waters, Kathleen M; Schulte, Paul A; Mandel, Jack S; Morton, Roscoe F; Reding, Douglas J; Rosenman, Kenneth D

2012-09-01

Understanding glioma etiology requires determining which environmental factors are associated with glioma. Upper Midwest Health Study case-control participant work histories collected 1995-1998 were evaluated for occupational associations with glioma. "Exposures of interest" from our study protocol comprise our a priori hypotheses. Year-long or longer jobs for 1,973 participants were assigned Standard Occupational Classifications (SOC) and Standard Industrial Classifications (SIC). The analysis file includes 8,078 SIC- and SOC-coded jobs. For each individual, SAS 9.2 programs collated employment with identical SIC-SOC coding. Distributions of longest "total employment duration" (total years worked in jobs with identical industry and occupation codes, including multiple jobs, and non-consecutive jobs) were compared between cases and controls, using an industrial hygiene algorithm to group occupations. Longest employment duration was calculated for 780 cases and 1,156 controls. More case than control longest total employment duration was in the "engineer, architect" occupational group [16 cases, 10 controls, odds ratio (OR) 2.50, adjusted for age group, sex, age and education, 95% confidence interval (CI) 1.12-5.60]. Employment as a food processing worker [mostly butchers and meat cutters] was of borderline significance (27 cases, 21 controls, adjusted OR: 1.78, CI: 0.99-3.18). Among our exposures of interest work as engineers or as butchers and meat cutters was associated with increased glioma risk. Significant associations could be due to chance, because of multiple comparisons, but similar findings have been reported for other glioma studies. Our results suggest some possible associations but by themselves could not provide conclusive evidence. Copyright © 2012 Wiley Periodicals, Inc.

Fructose malabsorption in people with and without gout: A case-control study.

PubMed

Batt, Caitlin; Fanning, Niamh; Drake, Jill; Frampton, Christopher; Gearry, Richard B; Stamp, Lisa K

2017-10-01

Higher fructose intake has been associated with hyperuricaemia and gout. Some individuals malabsorb fructose in the small intestine. The aims of this study were to determine the rate of fructose malabsorption and the effects of gout and fructose malabsorption on serum urate in people with and without gout. A total of 100 people with gout (cases) were age and gender matched with one control without gout. After a low fructose diet, fructose malabsorption was measured using a hydrogen and methane breath test with a 35g fructose load. In a subgroup of 35 cases and 35 controls, serum urate response to the fructose load over 240 minutes was measured. There was no significant difference in the rate of fructose malabsorption between cases and controls (48% vs. 52%; p = 0.67). Cases had a significantly lower mean (SEM) serum urate cumulative incremental concentration from baseline-240 minutes (iAUC 0-240 ) compared to controls 0.97 (0.56) vs. 4.78 (0.55); p < 0.001. C max was significantly lower in cases compared to controls [0.38 (0.003) vs. 0.40 (0.003); p < 0.001]. 95% of cases were receiving allopurinol. There was no significant difference between iAUC 0-240 or C max for malabsorbers compared to normal absorbers irrespective of case-control status. The mean (SEM) increase in serum urate between baseline and 30 minutes was 0.04 (0.004)mmol/l in the controls compared to 0.009 (0.002) in the cases (p < 0.001). The rates of fructose malabsorption are similar in people with and without gout. Allopurinol inhibits the increase in serum urate induced by a fructose load suggesting that people with gout receiving allopurinol may not need to restrict dietary intake of fructose. Copyright © 2017 Elsevier Inc. All rights reserved.

Quieting Weinberg 5C: a case study in hospital noise control.

PubMed

MacLeod, Mark; Dunn, Jeffrey; Busch-Vishniac, Ilene J; West, James E; Reedy, Anita

2007-06-01

Weinberg 5C of Johns Hopkins Hospital is a very noisy hematological cancer unit in a relatively new building of a large medical campus. Because of the requirements for dealing with immuno-suppressed patients, options for introducing sound absorbing materials are limited. In this article, a case study of noise control in a hospital, the sound environment in the unit before treatment is described, the chosen noise control approach of adding custom-made sound absorbing panels is presented, and the impact of the noise control installation is discussed. The treatment of Weinberg 5C involved creating sound absorbing panels of 2-in.-thick fiberglass wrapped in an anti-bacterial fabric. Wallpaper paste was used to hold the fabric to the backing of the fiberglass. Installation of these panels on the ceiling and high on corridor walls had a dramatic effect. The noise on the unit (as measured by the equivalent sound pressure level) was immediately reduced by 5 dB(A) and the reverberation time dropped by a factor of over 2. Further, this drop in background noise and reverberation time understates the dramatic impact of the change. Surveys of staff and patients before and after the treatment indicated a change from viewing the unit as very noisy to a view of the unit as relatively quiet.

Modified metabolic syndrome and second cancers in women: A case control study.

PubMed

Ortiz-Mendoza, Carlos-Manuel; Pérez-Chávez, Ernesto; Fuente-Vera, Tania-Angélica De-la

2016-01-01

According to some studies, the metabolic syndrome causes diverse primary cancers; however, there is no evidence about metabolic syndrome impact on second cancers development in women. To find out the implication of the modified metabolic syndrome in women with second cancers. This was a case-control study, at a general hospital in Mexico City, in women with second cancers (cases) and age-matched women with only one neoplasm (controls). The analysis comprised: Tumor (s), anthropometric features, and body mass index (BMI); moreover, presence of diabetes mellitus, hypertension, and fasting serum levels of total cholesterol, triglycerides and glucose. The sample was of nine cases and 27 controls. In cases, the metabolic syndrome (diabetes mellitus or glucose > 99 mg/dL + hypertension or blood pressure ≥ 135/85 mm Hg + triglycerides > 149 mg/dL or BMI ≥ 30 kg/m 2 ) was more frequent (odds ratio 20.8, 95% confidence interval: 1.9-227.1). Our results suggest that in women, the modified metabolic syndrome may be a risk factor for second cancers.

[Risk factors associated with trigger finger. Case-control study].

PubMed

De la Parra-Márquez, Miguel Leonardo; Tamez-Cavazos, Roberto; Zertuche-Cedillo, Luis; Martínez-Pérez, Juan José; Velasco-Rodríguez, Víctor; Cisneros-Pérez, Vicente

2008-01-01

We undertook this study to identify risk factors in our population associated with trigger finger. The study was conducted at the Instituto Mexicano del Seguro Social, UMAE 21, Monterrey, Nuevo Leon, Mexico. This was a case-control, retrospective, and observational study. There were 250 patients in each group. For cases, patients who were operated on for trigger finger from March 2006 to August 2006 were included. Controls included patients admitted to the Emergency Department with hand injuries that fulfilled the selection criteria. Risk factors analyzed were diabetes, hypertension, smoking, sex, age, weight, and 19 different occupations. Mean age of the cases was 52 years (SE +/- 14.19 years) with a median and mode of 53 years. The right hand was the most common with the middle, thumb, ring, index and little fingers, respectively. A significant statistical relationship was found: females (OR 7.57, 95% CI 5.07-11.31); diabetes (OR 3.72, 95% CI 2.43-5.70); obesity (OR 1.49, 95% CI 1.02-2.19). With regard to occupation, a statistical relationship was found: homemaker (OR 2.44, 95% CI 1.62-3.69); seamstress (OR 4.8, 95% CI 1.3-21.6); and secretary (OR 2.74, 95% CI 1.38-5.52). Trigger finger is a common pathology in our population and is more frequent in women >53 years old. It may be related to diabetes, body mass index (obesity) and certain occupations such as secretary, seamstress and homemaker.

Survey on large scale system control methods

NASA Technical Reports Server (NTRS)

Mercadal, Mathieu

1987-01-01

The problem inherent to large scale systems such as power network, communication network and economic or ecological systems were studied. The increase in size and flexibility of future spacecraft has put those dynamical systems into the category of large scale systems, and tools specific to the class of large systems are being sought to design control systems that can guarantee more stability and better performance. Among several survey papers, reference was found to a thorough investigation on decentralized control methods. Especially helpful was the classification made of the different existing approaches to deal with large scale systems. A very similar classification is used, even though the papers surveyed are somehow different from the ones reviewed in other papers. Special attention is brought to the applicability of the existing methods to controlling large mechanical systems like large space structures. Some recent developments are added to this survey.

A case-control study of Yersinia enterocolitica infections in Auckland.

PubMed

Satterthwaite, P; Pritchard, K; Floyd, D; Law, B

1999-10-01

To identify major risk factors for Yersinia enterocolitica (YE) and identify measures to reduce YE infections. A prospective case control study, group age matched, using 186 cases of YE identified by community pathology laboratories and 379 randomly selected controls. Conducted between April 1995 and June 1996 in Auckland, New Zealand. Face-to-face interviews used a standardised questionnaire examining exposures to factors potentially associated with YE infections including untreated water, unreticulated sewerage, consumption of selected foods, selected food handling practices and socio-demographic factors. Multivariate logistic regression was used to calculate adjusted odds ratios for the potential risk factors. Population attributable risk (PAR) was calculated for significant exposures. Having more than two people living in the home was more common among cases than controls (OR = 2.2). Town supply water (OR = 0.2), reticulated sewerage (OR = 0.34) and looking after a young child (OR = 0.51) were significantly less common. Of the meats, only pork (OR = 1.34) had a higher consumption rate, while bacon (OR = 0.75) and smallgoods (OR = 0.73) were consumed less frequently by cases than controls. Eating food from a sandwich bar was more frequent among cases (OR = 1.18). Fruit and vegetable consumption was marginally less (OR = 0.98). The population attributable risk of these factors was 0.89, implying that 89% of YE would be eliminated if adverse exposures were removed. The risk of YE illness is increased by contact with untreated water, unreticulated sewerage and consumption of pork. Investigation of non-town water supply, informal sewerage systems and methods of preparation and consumption of pork are recommended to determine how YE enters the human food chain.

A case-control study of airways obstruction among construction workers.

PubMed

Dement, John; Welch, Laura; Ringen, Knut; Quinn, Patricia; Chen, Anna; Haas, Scott

2015-10-01

While smoking is the major cause of chronic obstructive pulmonary disease (COPD), occupational exposures to vapors, gases, dusts, and fumes (VGDF) increase COPD risk. This case-control study estimated the risk of COPD attributable to occupational exposures among construction workers. The study population included 834 cases and 1243 controls participating in a national medical screening program for older construction workers between 1997 and 2013. Qualitative exposure indices were developed based on lifetime work and exposure histories. Approximately 18% (95% CI = 2-24%) of COPD risk can be attributed to construction-related exposures, which are additive to the risk contributed by smoking. A measure of all VGDF exposures combined was a strong predictor of COPD risk. Construction workers are at increased risk of COPD as a result of broad and complex effects of many exposures acting independently or interactively. Control methods should be implemented to prevent worker exposures, and smoking cessation should be promoted. © 2015 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.

Breast cancer risk and genetic ancestry: a case-control study in Uruguay.

PubMed

Bonilla, Carolina; Bertoni, Bernardo; Hidalgo, Pedro C; Artagaveytia, Nora; Ackermann, Elizabeth; Barreto, Isabel; Cancela, Paula; Cappetta, Mónica; Egaña, Ana; Figueiro, Gonzalo; Heinzen, Silvina; Hooker, Stanley; Román, Estela; Sans, Mónica; Kittles, Rick A

2015-01-01

Uruguay exhibits one of the highest rates of breast cancer in Latin America, similar to those of developed nations, the reasons for which are not completely understood. In this study we investigated the effect that ancestral background has on breast cancer susceptibility among Uruguayan women. We carried out a case-control study of 328 (164 cases, 164 controls) women enrolled in public hospitals and private clinics across the country. We estimated ancestral proportions using a panel of nuclear and mitochondrial ancestry informative markers (AIMs) and tested their association with breast cancer risk. Nuclear individual ancestry in cases was (mean ± SD) 9.8 ± 7.6% African, 13.2 ± 10.2% Native American and 77.1 ± 13.1% European, and in controls 9.1 ± 7.5% African, 14.7 ± 11.2% Native American and 76.2 ± 14.2% European. There was no evidence of a difference in nuclear or mitochondrial ancestry between cases and controls. However, European mitochondrial haplogroup H was associated with breast cancer (OR = 2.0; 95% CI 1.1, 3.5). We have not found evidence that overall genetic ancestry differs between breast cancer patients and controls in Uruguay but we detected an association of the disease with a European mitochondrial lineage, which warrants further investigation.

On estimation of time-dependent attributable fraction from population-based case-control studies.

PubMed

Zhao, Wei; Chen, Ying Qing; Hsu, Li

2017-09-01

Population attributable fraction (PAF) is widely used to quantify the disease burden associated with a modifiable exposure in a population. It has been extended to a time-varying measure that provides additional information on when and how the exposure's impact varies over time for cohort studies. However, there is no estimation procedure for PAF using data that are collected from population-based case-control studies, which, because of time and cost efficiency, are commonly used for studying genetic and environmental risk factors of disease incidences. In this article, we show that time-varying PAF is identifiable from a case-control study and develop a novel estimator of PAF. Our estimator combines odds ratio estimates from logistic regression models and density estimates of the risk factor distribution conditional on failure times in cases from a kernel smoother. The proposed estimator is shown to be consistent and asymptotically normal with asymptotic variance that can be estimated empirically from the data. Simulation studies demonstrate that the proposed estimator performs well in finite sample sizes. Finally, the method is illustrated by a population-based case-control study of colorectal cancer. © 2017, The International Biometric Society.

Extravasation of contrast medium during CT examination: an observational case-control study.

PubMed

Alami, Zayneb; Nasri, Siham; Ahid, Samir; Kacem, Hanane Hadj

2015-01-01

Extravasation is an adverse reaction to intravenous injection of contrast medium (CM) during CT examination. The objectives of this study are to determine the frequency, management and outcomes of extravasations and to assess risk factors for extravasation. Every incident of extravasation which occurred between March 2012 and March 31, 2013 was recorded in an extravasation form. Ethics Committee approval was obtained and the patients gave their consent to participate in the study. Data collected in the form included patients' age, sex, comorbidities, symptoms, CM used, injection mode, site and rate, extravasated volume, location of extravasation, severity of injury, treatment and patient outcome. Each case was matched with 4 controls of the same age ± 5 years and the same gender when possible. Extravasation occurred in 18 (7 women, 11 men) out of 2,000 injections of CM (0.9%) with a median age of 53 (10-78) years. Automated injection was performed in all cases with a mean rate of 1.7 ml/s. Large extravasated volumes (≥50 ml) were more observed in patients undergoing CT angiography (28.6% vs. 6.6%, although not significant P=0.112). Multivariate analysis revealed a significant association between patients with cardiac diseases and extravasation (OR: 7.3, 95% CI (1.09-49.05), P=0.04) whereas the injection rate is a protective factor from extravasation (P=0.002). Extravasation of CM results in mild to moderate adverse effects in all cases. Our study suggests that patients with cardiac disease are more predisposed to contrast extravasation than others. Further and larger studies are needed to confirm this trend.

Extravasation of contrast medium during CT examination: an observational case-control study

PubMed Central

Alami, Zayneb; Nasri, Siham; Ahid, Samir; Kacem, Hanane Hadj

2015-01-01

Introduction Extravasation is an adverse reaction to intravenous injection of contrast medium (CM) during CT examination. The objectives of this study are to determine the frequency, management and outcomes of extravasations and to assess risk factors for extravasation. Methods Every incident of extravasation which occurred between March 2012 and March 31, 2013 was recorded in an extravasation form. Ethics Committee approval was obtained and the patients gave their consent to participate in the study. Data collected in the form included patients’ age, sex, comorbidities, symptoms, CM used, injection mode, site and rate, extravasated volume, location of extravasation, severity of injury, treatment and patient outcome. Each case was matched with 4 controls of the same age ± 5 years and the same gender when possible. Results Extravasation occurred in 18 (7 women, 11 men) out of 2,000 injections of CM (0.9%) with a median age of 53 (10-78) years. Automated injection was performed in all cases with a mean rate of 1.7ml/s. Large extravasated volumes (≥ 50ml) were more observed in patients undergoing CT angiography (28.6% vs. 6.6%, although not significant P=0.112). Multivariate analysis revealed a significant association between patients with cardiac diseases and extravasation (OR: 7.3, 95% CI (1.09-49.05), P=0.04) whereas the injection rate is a protective factor from extravasation (P=0.002). Conclusion Extravasation of CM results in mild to moderate adverse effects in all cases. Our study suggests that patients with cardiac disease are more predisposed to contrast extravasation than others. Further and larger studies are needed to confirm this trend. PMID:26090047

Mental illness, poverty and stigma in India: a case-control study.

PubMed

Trani, Jean-Francois; Bakhshi, Parul; Kuhlberg, Jill; Narayanan, Sreelatha S; Venkataraman, Hemalatha; Mishra, Nagendra N; Groce, Nora E; Jadhav, Sushrut; Deshpande, Smita

2015-02-23

To assess the effect of experienced stigma on depth of multidimensional poverty of persons with severe mental illness (PSMI) in Delhi, India, controlling for gender, age and caste. Matching case (hospital)-control (population) study. University Hospital (cases) and National Capital Region (controls), India. A case-control study was conducted from November 2011 to June 2012. 647 cases diagnosed with schizophrenia or affective disorders were recruited and 647 individuals of same age, sex and location of residence were matched as controls at a ratio of 1:2:1. Individuals who refused consent or provided incomplete interview were excluded. Higher risk of poverty due to stigma among PSMI. 38.5% of PSMI compared with 22.2% of controls were found poor on six dimensions or more. The difference in multidimensional poverty index was 69% between groups with employment and income of the main contributors. Multidimensional poverty was strongly associated with stigma (OR 2.60, 95% CI 1.27 to 5.31), scheduled castes/scheduled tribes/other backward castes (2.39, 1.39 to 4.08), mental illness (2.07, 1.25 to 3.41) and female gender (1.87, 1.36 to 2.58). A significant interaction between stigma, mental illness and gender or caste indicates female PSMI or PSMI from 'lower castes' were more likely to be poor due to stigma than male controls (p<0.001) or controls from other castes (p<0.001). Public stigma and multidimensional poverty linked to SMI are pervasive and intertwined. In particular for low caste and women, it is a strong predictor of poverty. Exclusion from employment linked to negative attitudes and lack of income are the highest contributors to multidimensional poverty, increasing the burden for the family. Mental health professionals need to be aware of and address these issues. 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.

Risk factors for idiopathic intracranial hypertension in men: a case-control study

PubMed Central

Fraser, J. Alexander; Bruce, Beau B.; Rucker, Janet; Fraser, Lisa-Ann; Atkins, Edward J.; Newman, Nancy J.; Biousse, Valérie

2009-01-01

Objective To identify risk factors for idiopathic intracranial hypertension (IIH) in men Design Case-control study. A 96-item telephone questionnaire, answered retrospectively, with cases recalling at the age of their diagnosis and controls recalling at the age of their corresponding case's diagnosis. Setting Outpatient clinics in two US tertiary care centers Participants The characteristics of 24 men with IIH were compared to those of 48 controls matched for sex, age, race, and World Health Organization body mass index (BMI) category. Main Outcome Measures Two previously validated questionnaires: the ADAM (Androgen Deficiency in Aging Males) questionnaire for testosterone deficiency and the Berlin questionnaire for obstructive sleep apnea (OSA), embedded within the telephone questionnaire. Analysis with Mantel-Haenszel odds ratios and mixed-effects logistic regression models accounted for matching. Results Cases and controls had similar enrollment matching characteristics. Although matching was successful by BMI category, there was a small difference between BMI values of cases and controls (cases: median 31.7, controls: median 29.9; p=0.03). After adjustment by BMI value, men with IIH were significantly more likely than controls to have a positive ADAM questionnaire for testosterone deficiency (OR: 17.4, 95% CI: 5.6-54.5; p<0.001) and significantly more likely to have either a positive Berlin questionnaire for OSA or history of diagnosed OSA (OR: 4.4, 95% CI: 1.5-12.9; p=0.03). Conclusions Men with IIH are more likely than controls to have symptoms associated with testosterone deficiency and OSA. These associations suggest a possible role for sex hormones and OSA in the pathogenesis of IIH in men. PMID:19945715

Identifiability of large-scale non-linear dynamic network models applied to the ADM1-case study.

PubMed

Nimmegeers, Philippe; Lauwers, Joost; Telen, Dries; Logist, Filip; Impe, Jan Van

2017-06-01

In this work, both the structural and practical identifiability of the Anaerobic Digestion Model no. 1 (ADM1) is investigated, which serves as a relevant case study of large non-linear dynamic network models. The structural identifiability is investigated using the probabilistic algorithm, adapted to deal with the specifics of the case study (i.e., a large-scale non-linear dynamic system of differential and algebraic equations). The practical identifiability is analyzed using a Monte Carlo parameter estimation procedure for a 'non-informative' and 'informative' experiment, which are heuristically designed. The model structure of ADM1 has been modified by replacing parameters by parameter combinations, to provide a generally locally structurally identifiable version of ADM1. This means that in an idealized theoretical situation, the parameters can be estimated accurately. Furthermore, the generally positive structural identifiability results can be explained from the large number of interconnections between the states in the network structure. This interconnectivity, however, is also observed in the parameter estimates, making uncorrelated parameter estimations in practice difficult. Copyright © 2017. Published by Elsevier Inc.

IgM-monoclonal gammopathy neuropathy and tremor: A first epidemiologic case control study

PubMed Central

Ahlskog, Matthew C.; Kumar, Neeraj; Mauermann, Michelle L.; Klein, Christopher J.

2012-01-01

Introduction Small case series suggest tremor occurs frequently in IgM-monoclonal gammopathy of undetermined significance (IgM-MGUS) neuropathy. Epidemiologic study to confirm this association is lacking. Whether the neuropathy or another remote IgM-effect is causal remains unsettled. Materials and methods An IgM-MGUS neuropathy case cohort (n=207) was compared to age, gender, and neuropathy impairment score (NIS) matched, other-cause neuropathy controls (n=414). Tremor details were extracted from structured neurologic evaluation. All patients underwent nerve conductions. Results Tremor occurrence was significantly higher in IgM-MGUS case cohort (29%) than in control cohort (9.2%) (p=0.001). In IgM-MGUS cases, tremor was associated with worse NIS (p=0.025) and demyelinating nerve conductions (p=0.020), but 11 of 60 (18%) IgM-MGUS cases with tremor had axonal neuropathy. In other-cause neuropathy controls, tremor was associated with axonal nerve conductions (p=0.03) but not with NIS severity (p=0.57). Tremor occurrence associated with older age in controls, (p=0.004) but not in IgM-MGUS cases (p=0.272). Most IgM-MGUS tremor cases (49/60) had a postural-kinetic tremor, 8 had rest tremor, 3 had mixed rest-action. Alternative causes of tremor was identified in 42% of IgM-MGUS cases, the most common type is inherited essential tremor 6/60 (p=0.04). Conclusions This first epidemiologic case-control study validates association between IgM-MGUS neuropathy and tremor. Among IgM-MGUS neuropathy cases, severity as well as type of neuropathy (demyelinating over axonal) correlated with tremor occurrence. IgM-MGUS paraproteinemia may increase tremor expression in persons recognized with common other risk factors for tremor. PMID:22475624

Optimal control of energy extraction in LES of large wind farms

NASA Astrophysics Data System (ADS)

Meyers, Johan; Goit, Jay; Munters, Wim

2014-11-01

We investigate the use of optimal control combined with Large-Eddy Simulations (LES) of wind-farm boundary layer interaction for the increase of total energy extraction in very large ``infinite'' wind farms and in finite farms. We consider the individual wind turbines as flow actuators, whose energy extraction can be dynamically regulated in time so as to optimally influence the turbulent flow field, maximizing the wind farm power. For the simulation of wind-farm boundary layers we use large-eddy simulations in combination with an actuator-disk representation of wind turbines. Simulations are performed in our in-house pseudo-spectral code SP-Wind. For the optimal control study, we consider the dynamic control of turbine-thrust coefficients in the actuator-disk model. They represent the effect of turbine blades that can actively pitch in time, changing the lift- and drag coefficients of the turbine blades. In a first infinite wind-farm case, we find that farm power is increases by approximately 16% over one hour of operation. This comes at the cost of a deceleration of the outer layer of the boundary layer. A detailed analysis of energy balances is presented, and a comparison is made between infinite and finite farm cases, for which boundary layer entrainment plays an import role. The authors acknowledge support from the European Research Council (FP7-Ideas, Grant No. 306471). Simulations were performed on the computing infrastructure of the VSC Flemish Supercomputer Center, funded by the Hercules Foundation and the Flemish Govern.

Unmatched Case-Control Study on Late Presentation of HIV Infection in Santiago, Cape Verde (2004–2011)

PubMed Central

Moreira, António L.; Fronteira, Inês; Augusto, Gonçalo Figueiredo; Martins, Maria Rosario O.

2016-01-01

Access to free antiretroviral therapy (ART) in Sub-Saharan Africa has been steadily increasing over the past decade. However, the success of large-scale ART programmes depends on timely diagnosis and early initiation of HIV care. This study characterizes late presenters to HIV care in Santiago (Cape Verde) between 2004 and 2011, and identifies factors associated with late presentation for care. We defined late presentation as persons presenting to HIV care with a CD4 count below 350 cells/mm3. An unmatched case-control study was conducted using socio-demographic and behavioural data of 368 individuals (191 cases and 177 controls) collected through an interviewer-administered questionnaire, comparing HIV patients late and early presented to care. Logistic regression was performed to estimate odds ratio and 95% confidence intervals. Results show that 51.9% were late presenters for HIV. No differences were found in gender distribution, marital status, or access to health services between cases and controls. Participants who undertook an HIV test by doctor indication were more likely to present late compared with those who tested for HIV by their own initiative. Also, individuals taking less time to initiate ART are more likely to present late. This study highlights the need to better understand reasons for late presentation to HIV care in Cape Verde. People in older age groups should be targeted in future approaches focused on late presenters to HIV care. PMID:26999167

Gender Differences in Hiccup Patients: Analysis of Published Case Reports and Case-Control Studies.

PubMed

Lee, Gyeong-Won; Kim, Rock Bum; Go, Se Il; Cho, Hyun Seop; Lee, Seung Jun; Hui, David; Bruera, Eduardo; Kang, Jung Hun

2016-02-01

Although sporadic male predominance in hiccup patients has been reported, the association between gender differences and triggering factors has rarely been evaluated in patients with hiccups. The aim of this study was to investigate whether gender differences exist in hiccup patients by analyzing all previously published hiccup literature containing gender and etiology information. Published literature on this topic was identified using a standardized search strategy in the PubMed, SCOPUS, and CINAHL electronic databases. The literature search included studies published from January 1990 to December 2013. Searches were limited to English-language publications. Of 476 identified studies, 318 studies were eligible including eight case-control studies that contained nonhiccup control groups. Triggering factors for hiccups were categorized into two types: central nervous system (CNS) and non-CNS causes. Odds ratios (ORs) were calculated for the eight case-control studies and event rates for the other studies by meta-analysis. In addition, gender differences and mean ages were analyzed for the case studies. Pooled OR was 2.42 (95% confidence interval [CI] 1.40-4.17) with inclination for male predominance. Subgroup analysis by cause showed clear male predominance in the non-CNS type with OR of 11.72 (95% CI 3.16-43.50), whereas indistinct in the CNS type with OR of 1.74 (95% CI 0.95-3.16). Of the remaining 310 studies with 864 patients, previous findings were consistent. Male predominance was consistent in non-CNS (85.1%, 95% CI 78.2-90.2) and unknown origin (82.2%, 95% CI 75.8-87.2) patients, whereas mitigating the sex discrepancy in those with CNS origin (65.8%, 95% CI 53.1-76.5). We demonstrated male predominance in hiccup patients. This gender difference for hiccups was more pronounced in patients with non-CNS causes, whereas indistinct in patients with CNS causes. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All

NFKB1 -94insertion/deletion ATTG polymorphism and cancer risk: Evidence from 50 case-control studies.

PubMed

Fu, Wen; Zhuo, Zhen-Jian; Chen, Yung-Chang; Zhu, Jinhong; Zhao, Zhang; Jia, Wei; Hu, Jin-Hua; Fu, Kai; Zhu, Shi-Bo; He, Jing; Liu, Guo-Chang

2017-02-07

Nuclear factor-kappa B1 (NF-κB1) is a pleiotropic transcription factor and key contributor to tumorigenesis in many types of cancer. Numerous studies have addressed the association of a functional insertion (I)/deletion (D) polymorphism (-94ins/delATTG, rs28362491) in the promoter region of NFKB1 gene with the risk of various types of cancer; however, their conclusions have been inconsistent. We therefore conducted a meta-analysis to reevaluate this association. PubMed, EMBASE, China National Knowledge infrastructure (CNKI), and WANFANG databases were searched through July 2016 to retrieve relevant studies. After careful assessment, 50 case-control studies, comprising 18,299 cases and 23,484 controls were selected. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were used to determine the strength of the association. The NFKB1 -94ins/delATTG polymorphism was associated with a decreased risk of overall cancer in the homozygote model (DD vs. II): OR = 0.75, 95% CI = 0.64-0.87); heterozygote model (ID vs. II): OR = 0.91, 95% CI = 0.83-0.99; recessive model (DD vs. ID/II): OR = 0.81, 95% CI = 0.71-0.91; dominant model (ID/DD vs. II): OR = 0.86, 95% CI = 0.78-0.95; and allele contrast model (D vs. I): OR = 0.88, 95% CI = 0.81-0.95). Subgroup and stratified analyses revealed decreased risks for lung cancer, nasopharyngeal carcinoma, prostate cancer, ovarian cancer, and oral squamous cell carcinoma, and this association held true also for Asians (especially Chinese subjects) in hospital-based studies, and in studies with quality scores less than nine. Well-designed, large-scale case-control studies are needed to confirm these results.

Individual Correlates of Podoconiosis in Areas of Varying Endemicity: A Case-Control Study

PubMed Central

Molla, Yordanos B.; Le Blond, Jennifer S.; Wardrop, Nicola; Baxter, Peter; Atkinson, Peter M.; Newport, Melanie J.; Davey, Gail

2013-01-01

Background Podoconiosis is a non-filarial form of elephantiasis resulting in lymphedema of the lower legs. Previous studies have suggested that podoconiosis arises from the interplay of individual and environmental factors. Here, our aim was to understand the individual-level correlates of podoconiosis by comparing 460 podoconiosis-affected individuals and 707 unaffected controls. Methods/principal findings This was a case-control study carried out in six kebeles (the lowest governmental administrative unit) in northern Ethiopia. Each kebele was classified into one of three endemicity levels: ‘low’ (prevalence <1%), ‘medium’ (1–5%) and ‘high’ (>5%). A total of 142 (30.7%) households had two or more cases of podoconiosis. Compared to controls, the majority of the cases, especially women, were less educated (OR = 1.7, 95% CI = 1.3 to 2.2), were unmarried (OR = 3.4, 95% CI = 2.6–4.6) and had lower income (t = −4.4, p<0.0001). On average, cases started wearing shoes ten years later than controls. Among cases, age of first wearing shoes was positively correlated with age of onset of podoconiosis (r = 0.6, t = 12.5, p<0.0001). Among all study participants average duration of shoe wearing was less than 30 years. Between both cases and controls, people in ‘high’ and ‘medium’ endemicity kebeles were less likely than people in ‘low’ endemicity areas to ‘ever’ have owned shoes (OR = 0.5, 95% CI = 0.4–0.7). Conclusions Late use of shoes, usually after the onset of podoconiosis, and inequalities in education, income and marriage were found among cases, particularly among females. There were clustering of cases within households, thus interventions against podoconiosis will benefit from household-targeted case tracing. Most importantly, we identified a secular increase in shoe-wearing over recent years, which may give opportunities to promote shoe-wearing without increasing stigma among those at high risk of

Identification and medical utilization of incident cases of alcohol dependence: A population-based case-control study.

PubMed

Pan, Chun-Hung; Li, Min-Shan; Yang, Tien-Wey; Huang, Ming-Chyi; Su, Sheng-Shiang; Hung, Yen-Ni; Chen, Chiao-Chicy; Kuo, Chian-Jue

2018-05-05

Patients with alcohol dependence (AD) often seek help from medical professionals due to alcohol-related diseases, but the overall distribution of medical specialties identifying new AD cases is unclear. We investigated how such cases were identified and how medical resources were utilized before the identification of AD in a nationwide cohort. We enrolled a population-based cohort (N = 1,000,000) using the National Health Insurance Research Database of Taiwan; 8181 cases with incident AD were retrieved between January 1, 2000, and December 31, 2010. For this nested case-control study, four controls were matched for age and sex with each case based on risk-set sampling. We measured various dimensions of medical utilization before AD was diagnosed, including department visited, physical comorbidity, and medication used. Conditional logistic regression was used for estimating the variables associated with AD. Patients living in less urbanized areas who were unemployed were more likely to develop AD. The highest proportions (34.2%) of AD cases were identified in the internal medicine department, followed by the emergency (22.3%) and psychiatry (18.7%) departments. AD patients had a higher risk of comorbid chronic hepatic disease (adjusted RR = 2.72, p < 0.001) before identification of AD than controls. AD patients also had greater numbers of hospital admissions than controls, including non-psychiatric and psychiatric hospitalizations. Outpatient visit numbers were similar for AD patients and controls. The findings indicate that clinicians providing care in diverse medical settings should be prepared to screen for unhealthy alcohol use and to mitigate its detrimental effects. Copyright © 2018 Elsevier B.V. All rights reserved.

Epidemiological risk factors in microscopic colitis: a prospective case-control study.

PubMed

Fernández-Bañares, Fernando; de Sousa, Monia R; Salas, Antonio; Beltrán, Belén; Piqueras, Marta; Iglesias, Eva; Gisbert, Javier P; Lobo, Beatriz; Puig-Diví, Valentí; García-Planella, Esther; Ordás, Ingrid; Andreu, Montserrat; Calvo, Marta; Montoro, Miguel; Esteve, Maria; Viver, Josep M

2013-02-01

The cause of collagenous colitis (CC) and lymphocytic colitis (LC) is unknown and epidemiological risk factors for CC and LC are not well studied. The aim was to evaluate in a case-control study epidemiological risk factors for CC and LC. In all, 120 patients with CC, 70 with CL, and 128 controls were included. For all cases and controls information was prospectively recorded. A binary logistic regression analysis was performed separately for CC and LC. Independent associations observed with the diagnosis of CC were: current smoking (odds ratio [OR], 2.4), history of polyarthritis (OR, 20.8), and consumption of lansoprazole (OR, 6.4), low-dose aspirin (OR, 3.8), beta-blockers (OR, 3.6), and angiotensin II receptor antagonists (OR 0.20). In the case of LC they were: current smoking (OR, 3.8), associated autoimmune diseases (OR, 8), and consumption of sertraline (OR, 17.5), omeprazole (OR 2.7), low-dose aspirin (OR, 4.7), and oral antidiabetic drugs (OR, 0.14). The consumption of drugs, current smoking, and associated autoimmune diseases were independently associated with the risk of microscopic colitis.

Preeclampsia and toxic metals: a case-control study in Kinshasa, DR Congo.

PubMed

Elongi Moyene, Jean-Pierre; Scheers, Hans; Tandu-Umba, Barthélémy; Haufroid, Vincent; Buassa-Bu-Tsumbu, Baudouin; Verdonck, Fons; Spitz, Bernard; Nemery, Benoit

2016-04-05

Preeclampsia is frequent in Kinshasa (Democratic Republic of Congo), especially during the dry season. We tested whether preeclampsia was associated with exposure to environmental metals. Using a case-control design, 88 women hospitalized with preeclampsia (cases) and 88 healthy pregnant women from the antenatal clinic (controls) were included in the study; 67 and 109 women were enrolled during the rainy and dry season, respectively. The concentrations of 24 elements were quantified by inductively coupled plasma mass spectrometry (ICP-MS) in 24-h urine collections. Differences in the urinary excretion of metals were investigated between cases and controls, and the interaction with season was assessed. Cases and controls were well matched regarding age, parity and duration of pregnancy. In controls, the urinary concentrations of most elements were substantially higher than reference values for adults from industrially developed countries, e.g. for lead: geometric mean (GM) 8.0 μg/L [25(th)-75(th) percentile 3.1-13.8]. The daily urinary excretions of 14 metals were significantly higher in women with preeclampsia than in control women, e.g. for lead: GM 61 μg/day (25(th)-75(th) percentile 8-345) in women with preeclampsia vs 9 μg/day (25(th)-75(th) percentile 3-21) in controls (p < 0.001). A significant interaction was found between season and preeclampsia for several elements, with higher urinary excretions in preeclamptic women than controls during the dry season, but not during the rainy season. This study revealed not only that women with preeclampsia excrete higher amounts of several toxic metals, especially lead, than control women, but also that this excretion exhibits seasonal variation, thus possibly explaining the high incidence and seasonal variation of preeclampsia in Kinshasa. Although the exact sources of this exposure are unknown, these findings underscore the need for preventing environmental exposures to lead and other toxic metals.

Cannabis use and cancer of the head and neck: case-control study.

PubMed

Aldington, Sarah; Harwood, Matire; Cox, Brian; Weatherall, Mark; Beckert, Lutz; Hansell, Anna; Pritchard, Alison; Robinson, Geoffrey; Beasley, Richard

2008-03-01

To investigate whether cannabis smoking increases the risk of head and neck cancer. Case-control study. Cases of head and neck cancer < or =55 years identified from hospital databases and the Cancer Registry, and controls randomly selected from the electoral roll completed interviewer-administered questionnaires. Logistic regression was used to estimate the relative risk of head and neck cancer. There were 75 cases and 319 controls. An increased risk of cancer was found with increasing tobacco use, alcohol consumption, and decreased income but not increasing cannabis use. The highest tertile of cannabis use (>8.3 joint years) was associated with a nonsignificant increased risk of cancer (relative risk = 1.6, 95% confidence interval, 0.5-5.2) after adjustment for confounding variables. Cannabis use did not increase the risk of head and neck cancer; however, because of the limited power and duration of use studied, a small or longer-term effect cannot be excluded.

Fibromyalgia: epidemiology and risk factors, a population-based case-control study in Lebanon.

PubMed

Moukaddem, Afaf; Chaaya, Monique; Slim, Zeinab F N; Jaffa, Miran; Sibai, Abla Mehio; Uthman, Imad

2017-02-01

To investigate the epidemiology of fibromyalgia (FM) and assess its risk factors. Using data from the 2009 Community Oriented Program for Control of Rheumatic Diseases (COPCORD) study conducted in Lebanon, a population-based case control study was performed. The sample included 34 FM patients, frequency matched with 136 controls free from any musculoskeletal complaints and randomly sampled from the population. The controls were frequency matched with cases by age and gender. The 34 female FM cases were prevalent cases which existed for a long period of time and all those who consulted a doctor were previously misdiagnosed. Family history of joint problems (OR = 4.93, 95% CI: 1.56-15.58) and working status (OR = 2.69, 95% CI: 1.04-6.93) were significant risk factors for FM, after adjusting for body mass index, distress level, smoking status and residence location. This was the first study to address the epidemiology of FM in Lebanon and the region. The chronic nature of FM that is characterized by frequent bouts of intense disabling pain and symptoms constitutes a significant health and economic burden. Clustering of cases in coastal areas was partially explained by other factors such as body mass index, distress level, smoking and work status. The high burden of FM found in our study calls for further investigation of potential risk factors of this condition. © 2015 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

A retrospective likelihood approach for efficient integration of multiple omics factors in case-control association studies.

PubMed

Balliu, Brunilda; Tsonaka, Roula; Boehringer, Stefan; Houwing-Duistermaat, Jeanine

2015-03-01

Integrative omics, the joint analysis of outcome and multiple types of omics data, such as genomics, epigenomics, and transcriptomics data, constitute a promising approach for powerful and biologically relevant association studies. These studies often employ a case-control design, and often include nonomics covariates, such as age and gender, that may modify the underlying omics risk factors. An open question is how to best integrate multiple omics and nonomics information to maximize statistical power in case-control studies that ascertain individuals based on the phenotype. Recent work on integrative omics have used prospective approaches, modeling case-control status conditional on omics, and nonomics risk factors. Compared to univariate approaches, jointly analyzing multiple risk factors with a prospective approach increases power in nonascertained cohorts. However, these prospective approaches often lose power in case-control studies. In this article, we propose a novel statistical method for integrating multiple omics and nonomics factors in case-control association studies. Our method is based on a retrospective likelihood function that models the joint distribution of omics and nonomics factors conditional on case-control status. The new method provides accurate control of Type I error rate and has increased efficiency over prospective approaches in both simulated and real data. © 2015 Wiley Periodicals, Inc.

Protective effect of intradermal BCG against leprosy; a case-control study in central Brazil.

PubMed

Rodrigues, M L; Silva, S A; Neto, J C; de Andrade, A L; Martelli, C M; Zicker, F

1992-09-01

A case-control study was undertaken to evaluate the protective efficacy of intradermal BCG against leprosy in a high-endemic area of leprosy in central Brazil. Sixty-two cases and 186 controls were included in the study. Cases were all newly diagnosed leprosy patients under 16 years of age attending an outpatient health service, and all of them were schoolchildren. Three controls under 16 years old, frequency matched by sex and age group, were selected from schools geographically located in the area from which the cases came. The presence of BCG was negatively associated with leprosy, indicating a 5.3 risk of leprosy for those nonvaccinated and protective efficacy of 81%. Paucibacillary patients were more likely to have a BCG scar than multibacillary patients.

National Case-Control Study of Homicide Offending and Methamphetamine Use

ERIC Educational Resources Information Center

Stretesky, Paul B.

2009-01-01

The purpose of this study is to examine the relationship between methamphetamine use and homicide. To carry out this study, data from the National Household Survey on Drug Abuse and Survey of Inmates in State and Federal Correctional Facilities were combined to create a case-control design. The main exposure measure is methamphetamine use and the…

Metformin for Primary Colorectal Cancer Prevention in Diabetic Patients: A Case-Control Study in a US Population

PubMed Central

Sehdev, Amikar; Shih, Ya-Chen T.; Vekhter, Benjamin; Bissonnette, Marc; Olopade, Olufunmilayo I.; Polite, Blase

2016-01-01

Background Emerging evidence from observational studies suggests that metformin may be beneficial in the primary prevention of colorectal cancer (CRC). However, none of these were conducted in a US population. Since environmental factors, such as Western diet and obesity, are implicated in the causation of CRC, we conducted a large case control study to assess the effects of metformin on CRC incidence in a US population. Methods MarketScan® databases were used to identify diabetic patients with CRC. A case was defined as having an incident diagnosis of CRC. Up to two controls matched for age, sex and geographical region, were selected for each case. Metformin exposure was assessed by prescription tracking in the 12 months period prior to the index date. Conditional logistic regression was used to adjust for multiple potential confounders and to calculate adjusted odds ratios (AOR). Results The mean age of participants was 55 and 57 years in the control and case group, respectively (p=1.0). Sixty percent of the study participants were males and 40% were females in each group. In the multivariable model, any metformin use was associated with 15% reduced odds of CRC (AOR, 0.85, 95% confidence interval (CI), 0.76–0.95, p<0.007). After adjusting for health-care utilization the beneficial effect of metformin was reduced to 12% (AOR, 0.88, 95% CI, 0.77–1.00, p=0.05). The dose-response analyses showed no significant association with metformin dose, duration or total exposure. Conclusions Metformin use is associated with reduced risk of developing CRC among diabetic patients in the US population. PMID:25424411

Risk of Psoriasis Following Terbinafine or Itraconazole Treatment for Onychomycosis: A Population-Based Case-Control Comparative Study.

PubMed

Chiu, Hsien-Yi; Chang, Wei-Lun; Tsai, Tsen-Fang; Tsai, Yi-Wen; Shiu, Ming-Neng

2018-03-01

Several case studies have reported an association between antifungal drug use and psoriasis risk. The objective of this study was to investigate the association between terbinafine/itraconazole exposure and psoriasis incidence. Among patients with onychomycosis in the Taiwan National Health Insurance Research Database, 3831 incident psoriasis cases were identified during 2004-2010 and compared with 3831 age- and sex-matched controls with the same look-back period. Multivariate conditional logistic regression was used for the analysis. The psoriasis cases were significantly more likely than matched controls to have used terbinafine or itraconazole (59.85 vs. 42.70%, respectively; p < 0.0001). After adjusting for potential confounders and cumulative duration of antifungal drug prescription, terbinafine/itraconazole use was associated with an increased psoriasis risk (adjusted odds ratio 1.33, 95% confidence interval 1.15-1.54). The association was stronger for more recent drug exposure (adjusted odds ratio 2.96, 95% confidence interval 2.25-3.90 for ≤ 90 days before the sampling date; adjusted odds ratio 1.04, 95% confidence interval 0.89-1.22 for > 360 days). In a comparison of patients receiving terbinafine or itraconazole only, psoriasis risk was higher for itraconazole (adjusted odds ratio 1.21, 95% confidence interval 1.05-1.40). This large population-based case-control analysis showed that exposure to terbinafine or itraconazole is associated with an increased risk of incident psoriasis. The finding of an increased psoriasis risk for antifungal drug users, particularly for itraconazole, deserves attention in clinical practice although further prospective studies are necessary to confirm our findings and clarify the biological mechanisms that underlie these associations.

Occupation and bladder cancer: a population-based, case-control study in Iowa.

PubMed

Zheng, Tongzhang; Cantor, Kenneth P; Zhang, Yawei; Lynch, Charles F

2002-07-01

While considerable efforts have been made to investigate the role of occupation and industry in the risk of bladder cancer, many reported associations have not been consistent, and strong evidence of increased risk is apparent for few occupational groups. To further examine the issue, a large, population-based, case-control study was conducted in the state of Iowa among both men and women. A total of 1452 incident bladder cancer cases and 2434 controls were included in the study. Occupational history was collected from respondents for each job held for 5 years or longer since age 16. Among men, excess risk was observed for industries including plumbing, heating, and air conditioning (odds ratio [OR], = 2.2; 95% confidence interval [CI], 1.0 to 5.0); rubber and plastic products (OR = 3.1; 95% CI, 1.2 to 8.5), motor vehicle parts and supplies (OR = 4.5; 95% CI, 1.2 to 16.5), and occupations including supervisors for transportation and material moving (OR = 6.5; 95% CI, 1.4 to 29.9), material-moving-equipment operators (OR = 1.9; 95% CI, 1.0 to 3.6), automobile mechanics (OR = 1.6; 95% CI, 1.0 to 2.6), painters (OR = 2.7; 95% CI, 1.0 to 7.7), and metal- and plastic-working machine operators (OR = 2.0; 95% CI, 1.1 to 3.4). Among women, significant excess risk was observed for secondary school teachers and record clerks. Housekeepers and butlers and workers in laundering and dry cleaning were also at increased risk. In conclusion, these results suggest that occupational exposures may play a significant role in the risk of bladder cancer.

Snippets From the Past: Is Flint, Michigan, the Birthplace of the Case-Control Study?

PubMed Central

Morabia, Alfredo

2013-01-01

In the summer of 1924, an outbreak of scarlet fever occurred in Flint, Michigan. Unable to trace it to the usual causes, particularly fresh milk, the Michigan Department of Health used a novel approach to disentangle the enigma: The 116 cases of scarlet fever were compared with 117 “controls” selected from neighbors of the quarantined cases and from patients at the City Health Center who had been treated for ailments unrelated to scarlet fever. The extraordinary culprit was ice cream, which had a frequent/occasional/none consumption prevalence of 60%, 34%, and 6% among the cases and 24%, 51%, and 25% among the controls, respectively. The 1925 report reads, “Detailed epidemiological investigation, by means of case histories and control histories on well persons, confirmed early suspicions and established the fact that the epidemic was spread by ice cream” (Am J Hyg. 1925;5(5):669–681). This forgotten epidemiologic study is the oldest study using the case-control design to have been resurrected thus far. The case-control study design may have been conceived simultaneously, but independently and for different purposes, in England (Janet Lane-Claypon's 1926 report on the determinants of breast cancer) and the United States. PMID:24064743

The Upper Midwest Health Study: Industry and Occupation of Glioma Cases and Controls

PubMed Central

Ruder, Avima M.; Waters, Martha A.; Carreón, Tania; Butler, Mary A.; Calvert, Geoffrey M.; Davis-King, Karen E.; Waters, Kathleen M.; Schulte, Paul A.; Mandel, Jack S.; Morton, Roscoe F.; Reding, Douglas J.; Rosenman, Kenneth D.

2015-01-01

Background Understanding glioma etiology requires determining which environmental factors are associated with glioma. Upper Midwest Health Study case–control participant work histories collected 1995–1998 were evaluated for occupational associations with glioma. “Exposures of interest” from our study protocol comprise our a priori hypotheses. Materials and Methods Year-long or longer jobs for 1,973 participants were assigned Standard Occupational Classifications (SOC) and Standard Industrial Classifications (SIC). The analysis file includes 8,078 SIC- and SOC-coded jobs. For each individual, SAS 9.2 programs collated employment with identical SIC-SOC coding. Distributions of longest “total employment duration” (total years worked in jobs with identical industry and occupation codes, including multiple jobs, and non-consecutive jobs) were compared between cases and controls, using an industrial hygiene algorithm to group occupations. Results Longest employment duration was calculated for 780 cases and 1,156 controls. More case than control longest total employment duration was in the “engineer, architect” occupational group [16 cases, 10 controls, odds ratio (OR) 2.50, adjusted for age group, sex, age and education, 95% confidence interval (CI) 1.12–5.60]. Employment as a food processing worker [mostly butchers and meat cutters] was of borderline significance (27 cases, 21 controls, adjusted OR: 1.78, CI: 0.99–3.18). Conclusions Among our exposures of interest work as engineers or as butchers and meat cutters was associated with increased glioma risk. Significant associations could be due to chance, because of multiple comparisons, but similar findings have been reported for other glioma studies. Our results suggest some possible associations but by themselves could not provide conclusive evidence. PMID:22715102

Dentine sensitivity risk factors: A case-control study.

PubMed

Mafla, Ana Cristina; Lopez-Moncayo, Luis Fernando

2016-01-01

To identify the clinical and psychological risk factors associated with dentine hypersensitivity (DH) in order to provide an early diagnosis and preventive therapy. A nested case-control study was design between 2011 and 2012. A total of 61 DH cases and 122 controls participated in this investigation. Cases and controls were matched for sex, group of age and socioeconomic status in a ratio of 1:2. DH to different stimuli such as cold, heat, acid, and sweet was asked in patient interviews, and dental examinations were used to detect DH. Clinical and psychological risk factors such as dental hygiene, periodontal disease, acid diet, alcohol consumption, psychological stress, and psychopathological symptoms were inquired. Psychological stress was measured through the PSS-10 and psychopathological symptoms were evaluated by SCL-90-R in Spanish. Descriptive and univariate binary logistic regression analysis were performed to estimate the association between clinical and psychological risk factors and the presence of DH. Toothpaste abrasivity (odds ratio [OR] 1.881, 95% confidence interval [CI] 1.010-3.502, P = 0.045), gingival recession (OR 2.196, 95% CI 1.020-4.728, P = 0.041), and periodontal therapy (OR 5.357, 95% CI 2.051-13.993, P < 0.001) were associated with DH. Subjects with perceived stress (OR 1.211, 95%, CI 0.518-2.833, P = 0.658), obsessive-compulsive (OR 1.266, 95%, CI 0.494-3.240, P = 0.623) and hostility (OR 1.235, 95%, CI 0.507-3.007, P = 0.642) symptoms had a clinical greater odd of DH. Oral hygiene products and periodontal conditions are important risk factors for DH. Individuals with perceived stress, obsessive-compulsive, and hostility symptoms may increase a clinical risk for this entity. Targeting to dental counseling focused on oral hygiene products, periodontal therapy and a psychological evaluation may be promising in DH prevention.

Risk factors associated with deforming oral habits in children aged 5 to 11: a case-control study.

PubMed

Reyes Romagosa, Daniel Enrique; Paneque Gamboa, María Rosa; Almeida Muñiz, Yamilka; Quesada Oliva, Leticia María; Escalona Oliva, Damiana; Torres Naranjo, Sonia

2014-03-31

Dental and maxillofacial anomalies have multiple and complex causes. Most frequent among these are poor oral habits. A large number of children present with oral malocclusions, most of which are caused by deforming oral habits. It is important to learn about risk factors for this condition in order to institute preventive measures, early detection and treatment, and identification of low- and high-risk groups. To identify risk factors associated with deforming oral habits, which, if maintained over time, are responsible for occlusion defects, speech disorders, and can affect physical and emotional child development. A case-control study of children presenting with deforming oral habits in the municipality of Manzanillo in Granma province was conducted between January and August 2013. 540 children aged 5 to 11 were included of which 180 had deforming oral habits and were asked to fill out a survey to identify specific type of habits leading to malocclusion. The case group was composed of children with deforming habits, and the remaining 360 children without poor oral habits were the control group. Each case was randomly matched to two control cases. The children mothers were also surveyed to gather supplemental information. Children with deforming oral habits were mostly female. At age 10, onychophagia was the predominant oral deforming habit. Risk factors detected for these habits were sociobiological maternal and child variables such as low and high birth weight, maternal breastfeeding inexperience, and discord in the family. The study identified likely risk factors associated with deforming oral habits. These are discord in the family, birth weight, and lack of breastfeeding experience.

Urine output on an intensive care unit: case-control study

PubMed Central

Kirwan, Christopher J; Alexander, Neal D E; Nimako, Kofi; Jurukov, Angela; Forth, Rebecca J; Rahman, Tony M

2010-01-01

Objective To compare urine output between junior doctors in an intensive care unit and the patients for whom they are responsible. Design Case-control study. Setting General intensive care unit in a tertiary referral hospital. Participants 18 junior doctors responsible for clerking patients on weekday day shifts in the unit from 23 March to 23 April 2009 volunteered as “cases.” Controls were the patients in the unit clerked by those doctors. Exclusion criteria (for both groups) were pregnancy, baseline estimated glomerular filtration rate <15 ml/min/1.73 m2, and renal replacement therapy. Main outcome measures Oliguria (defined as mean urine output <0.5 ml/kg/hour over six or more hours of measurement) and urine output (in ml/kg/hour) as a continuous variable. Results Doctors were classed as oliguric and “at risk” of acute kidney injury on 19 (22%) of 87 shifts in which urine output was measured, and oliguric to the point of being “in injury” on one (1%) further shift. Data were available for 208 of 209 controls matched to cases in the data collection period; 13 of these were excluded because the control was receiving renal replacement therapy. Doctors were more likely to be oliguric than their patients (odds ratio 1.99, 95% confidence interval 1.08 to 3.68, P=0.03). For each additional 1 ml/kg/hour mean urine output, the odds ratio for being a case rather than a control was 0.27 (0.12 to 0.58, P=0.001). Mortality among doctors was astonishingly low, at 0% (0% to 18%). Conclusions Managing our own fluid balance is more difficult than managing it in our patients. We should drink more water. Modifications to the criteria for acute kidney injury could be needed for the assessment of junior doctors in an intensive care unit. PMID:21156738

Urine output on an intensive care unit: case-control study.

PubMed

Solomon, Anthony W; Kirwan, Christopher J; Alexander, Neal D E; Nimako, Kofi; Jurukov, Angela; Forth, Rebecca J; Rahman, Tony M

2010-12-14

To compare urine output between junior doctors in an intensive care unit and the patients for whom they are responsible. Case-control study. General intensive care unit in a tertiary referral hospital. 18 junior doctors responsible for clerking patients on weekday day shifts in the unit from 23 March to 23 April 2009 volunteered as "cases." Controls were the patients in the unit clerked by those doctors. Exclusion criteria (for both groups) were pregnancy, baseline estimated glomerular filtration rate <15 ml/min/1.73 m(2), and renal replacement therapy. Oliguria (defined as mean urine output <0.5 ml/kg/hour over six or more hours of measurement) and urine output (in ml/kg/hour) as a continuous variable. Doctors were classed as oliguric and "at risk" of acute kidney injury on 19 (22%) of 87 shifts in which urine output was measured, and oliguric to the point of being "in injury" on one (1%) further shift. Data were available for 208 of 209 controls matched to cases in the data collection period; 13 of these were excluded because the control was receiving renal replacement therapy. Doctors were more likely to be oliguric than their patients (odds ratio 1.99, 95% confidence interval 1.08 to 3.68, P=0.03). For each additional 1 ml/kg/hour mean urine output, the odds ratio for being a case rather than a control was 0.27 (0.12 to 0.58, P=0.001). Mortality among doctors was astonishingly low, at 0% (0% to 18%). Managing our own fluid balance is more difficult than managing it in our patients. We should drink more water. Modifications to the criteria for acute kidney injury could be needed for the assessment of junior doctors in an intensive care unit.

Consanguinity and epilepsy in Oran, Algeria: A case-control study.

PubMed

Chentouf, Amina; Talhi, Randa; Dahdouh, Aicha; Benbihi, Latifa; Benilha, Soumia; Oubaiche, Mohand Laid; Chaouch, Malika

2015-03-01

The goal of this case-control study was to identify the significance of consanguinity and other risk factors for epilepsy in Oran, Algeria. Unrelated epileptic patients upwards of 16 years, who attended the Neurology Department between October 2013 and March 2014 were included in the study. Controls, matched for age and sex, were selected among non-epileptic patients attending the same department during the same period. The risk factors evaluated were: consanguinity, family history of epilepsy, perinatal complications, infection of the central nervous system, mental retardation, neurological impairment, history of febrile seizures, severe head trauma, cerebrovascular diseases, and addiction. 101 cases and 202 controls participated in the study. Multivariate logistic regression identified five factors significantly associated with epilepsy: first-degree of consanguinity (odds ratio (OR)=2.15), history of epilepsy in first-degree relatives (OR=4.03), antecedent of febrile seizures (OR=5.38), severe head injury (OR=2.94) and mental retardation (OR=9.32). Consanguinity, family history of epilepsy, history of febrile seizures, severe head trauma and mental retardation are risk factors for epilepsy. The implementation of a strategy for prevention and awareness of the impact of consanguineous marriages as well as genetic counseling for couples with a family history of epilepsy are needed. Copyright © 2015 Elsevier B.V. All rights reserved.

[Lung cancer and vegetable consumption in Asturias, Spain. A case control study].

PubMed

Caicoya, Martín

2002-07-13

Lung cancer in Asturias (Northern Spain) exceeds the Spanish average by 1.4 times. While the proportion of smokers is similar, consumption of vegetables is the lowest of Spain. The objective of the study was to examine the relationship between lung cancer and vegetable consumption in Asturias. This was an incident, hospital-based, case-control study. Cases were newly diagnosed lung cancer patients and controls were patients from surgical wards. Diet habits were obtained by means of a food frequency questionnaire with one year recall time. Information was also sought on smoking, occupational exposure and demographic variables. 197 cases and 196 controls were included in the study. Those at the 80th percentile of cruciferous (e.g, cabbage, broccoli) consumption had half the risk of lung cancer, other than adenocarcinoma, as compared to those at the 20th percentile [OR = 0.47; 95% CI, 0.23-0.95 in the crude analysis]. However, when adjusting for smoking and social class, the association was no longer significant, possibly due to a low power of the study. A high vegetable, vitamin A or betacarotene consumption was not associated with a lower risk of lung cancer. This study points towards a protective effect of cruciferous vegetables in lung cancer, other than adenocarcinoma. However, even in the case such a vegetable were protective, it could not explain by itself the existing differences in lung cancer rates between Asturias and the the rest of Spain.

Design and validity of a clinic-based case-control study on the molecular epidemiology of lymphoma

PubMed Central

Cerhan, James R; Fredericksen, Zachary S; Wang, Alice H; Habermann, Thomas M; Kay, Neil E; Macon, William R; Cunningham, Julie M; Shanafelt, Tait D; Ansell, Stephen M; Call, Timothy G; Witzig, Thomas E; Slager, Susan L; Liebow, Mark

2011-01-01

We present the design features and implementation of a clinic-based case-control study on the molecular epidemiology of lymphoma conducted at the Mayo Clinic (Rochester, Minnesota, USA), and then assess the internal and external validity of the study. Cases were newly diagnosed lymphoma patients from Minnesota, Iowa and Wisconsin seen at Mayo and controls were patients from the same region without lymphoma who had a pre-scheduled general medical examination, frequency matched on age, sex and residence. Overall response rates were 67% for cases and 70% for controls; response rates were lower for cases and controls over age 70 years, cases with more aggressive disease, and controls from the local area, although absolute differences were modest. Cases and controls were well-balanced on age, sex, and residence characteristics. Demographic and disease characteristics of NHL cases were similar to population-based cancer registry data. Control distributions were similar to population-based data on lifestyle factors and minor allele frequencies of over 500 SNPs, although smoking rates were slightly lower. Associations with NHL in the Mayo study for smoking, alcohol use, family history of lymphoma, autoimmune disease, asthma, eczema, body mass index, and single nucleotide polymorphisms in TNF (rs1800629), LTA (rs909253), and IL10 (rs1800896) were at a magnitude consistent with estimates from pooled studies in InterLymph, with history of any allergy the only directly discordant result in the Mayo study. These data suggest that this study should have strong internal and external validity. This framework may be useful to others who are designing a similar study. PMID:21686124

OPTIMIZED REAL-TIME CONTROL OF COMBINED SEWERAGE SYSTEMS: TWO CASE STUDIES

EPA Science Inventory

The paper presents results of two case studies of Real-Time Control (RTC) alternatives evaluations that were conducted on portions of sewerage systems near Paris, France and in Quebec City, Canada, respectively. The studies were performed at real-scale demonstration sites. RTC ...

Control of large space structures

NASA Technical Reports Server (NTRS)

Gran, R.; Rossi, M.; Moyer, H. G.; Austin, F.

1979-01-01

The control of large space structures was studied to determine what, if any, limitations are imposed on the size of spacecraft which may be controlled using current control system design technology. Using a typical structure in the 35 to 70 meter size category, a control system design that used actuators that are currently available was designed. The amount of control power required to maintain the vehicle in a stabilized gravity gradient pointing orientation that also damped various structural motions was determined. The moment of inertia and mass properties of this structure were varied to verify that stability and performance were maintained. The study concludes that the structure's size is required to change by at least a factor of two before any stability problems arise. The stability margin that is lost is due to the scaling of the gravity gradient torques (the rigid body control) and as such can easily be corrected by changing the control gains associated with the rigid body control. A secondary conclusion from the study is that the control design that accommodates the structural motions (to damp them) is a little more sensitive than the design that works on attitude control of the rigid body only.

Demographic risk factors of self-immolation: a case-control study.

PubMed

Ahmadi, Alireza; Mohammadi, Reza; Schwebel, David C; Khazaie, Habibolah; Yeganeh, Naser; Almasi, Afshin

2009-06-01

To investigate demographic risk factors for self-immolation patients. In a case-control study, 30 consecutive cases of deliberate self-inflicted burns admitted to the regional Burn centre (Imam Khomeini hospital in Kermanshah province, Iran) were compared with 30 controls who were selected from the community and matched by gender, age, and living area. All cases and controls were reviewed for demographic variables, including: age, gender, living area, family size, marital status, bearing and number of children, Body Mass Index (BMI), birth order, employment state, educational status, early school drop-out, and parent/guardian employment status. Two variables emerged as related to risk of self-immolation. Being the first or last child in family birth order was associated with increased risk of self-immolation. Moreover, among the married participants, having children was associated with decreased risk of self-immolation. The comparisons of other variables were not statistically significant. In multivariate analyses, none of the variables predicted risk for self-immolation. This study suggests that being the first or last child of a family might be a risk factor for self-immolation. For married persons, having children might serve as a protective factor from self-immolation. Other variables such as family size, marital status, number of children, BMI, employment state, educational status, early school drop-out, and parent/guardian employment status did not play a role as individually protective or risk factors for self-immolation.

Case control study of neuroblastoma in west-Germany after the Chernobyl accident.

PubMed

Michaelis, J; Haaf, H G; Zöllner, J; Kaatsch, P; Krummenauer, F; Berthold, F

1996-01-01

To explore possible causes of a 1988 incidence peak of infant neuroblastoma in west German regions which were contaminated with more than 6000 Bq/m2 Cs137 from the Chernobyl accident. The primary working hypothesis was that parents of the diseased children had been contaminated by an excessive intake of locally produced food, especially mushrooms or deer. Case control study with 1:2 (cases:controls) matching. Data were collected from the children's parents by questionnaires and telephone interviews. Nation-wide study (former FRG) based on the German Childhood Cancer Registry. Cases born in 1988 and reported with a neuroblastoma to the registry until March 1992. Population-based healthy controls, matched for age, sex and residence at time of diagnosis. The working hypothesis could not be confirmed by the study, because the parents of cases tended to eat less locally grown food than the parents of controls (RR = 0.63, 95% CI:0.20-1.97). Possible influence factors which previously have been described to be associated with neuroblastoma incidence could not be confirmed by the study. Parental exposure to herbicides and pesticides was associated with the occurrence of neuroblastoma (RR = 4.2, 95% CI:1.4-12.9). Neuroblastoma stage distribution in the contaminated regions was shifted towards lower stages as compared to the less contaminated regions and previous age cohorts. The study does not show additional evidence that the observed increase in neuroblastoma incidence might have been caused by exposure to fallout from the Chernobyl accident. The observed shift towards lower clinical stages may rather indicate increased diagnostic awareness. The association between neuroblastoma and parental exposure with herbicides and pesticides resulted from an extensive exploratory data analysis and needs to be confirmed in further studies.

Selection bias in population-based cancer case-control studies due to incomplete sampling frame coverage.

PubMed

Walsh, Matthew C; Trentham-Dietz, Amy; Gangnon, Ronald E; Nieto, F Javier; Newcomb, Polly A; Palta, Mari

2012-06-01

Increasing numbers of individuals are choosing to opt out of population-based sampling frames due to privacy concerns. This is especially a problem in the selection of controls for case-control studies, as the cases often arise from relatively complete population-based registries, whereas control selection requires a sampling frame. If opt out is also related to risk factors, bias can arise. We linked breast cancer cases who reported having a valid driver's license from the 2004-2008 Wisconsin women's health study (N = 2,988) with a master list of licensed drivers from the Wisconsin Department of Transportation (WDOT). This master list excludes Wisconsin drivers that requested their information not be sold by the state. Multivariate-adjusted selection probability ratios (SPR) were calculated to estimate potential bias when using this driver's license sampling frame to select controls. A total of 962 cases (32%) had opted out of the WDOT sampling frame. Cases age <40 (SPR = 0.90), income either unreported (SPR = 0.89) or greater than $50,000 (SPR = 0.94), lower parity (SPR = 0.96 per one-child decrease), and hormone use (SPR = 0.93) were significantly less likely to be covered by the WDOT sampling frame (α = 0.05 level). Our results indicate the potential for selection bias due to differential opt out between various demographic and behavioral subgroups of controls. As selection bias may differ by exposure and study base, the assessment of potential bias needs to be ongoing. SPRs can be used to predict the direction of bias when cases and controls stem from different sampling frames in population-based case-control studies.

Air Pollution and Pulmonary Tuberculosis: A Nested Case-Control Study among Members of a Northern California Health Plan.

PubMed

Smith, Geneé S; Van Den Eeden, Stephen K; Garcia, Cynthia; Shan, Jun; Baxter, Roger; Herring, Amy H; Richardson, David B; Van Rie, Annelies; Emch, Michael; Gammon, Marilie D

2016-06-01

Ecologic analyses, case-case comparisons, and animal experiments suggest positive associations between air pollution and tuberculosis. We evaluated this hypothesis in a large sample, which yielded results that are applicable to the general population. We conducted a case-control study nested within a cohort of Kaiser Permanente of Northern California members. All active pulmonary tuberculosis (TB) cases newly diagnosed between 1996 and 2010 (n = 2,309) were matched to two controls (n = 4,604) by age, sex, and race/ethnicity on the index date corresponding with the case diagnosis date. Average individual-level concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5) and 10 μm (PM10) for 2 years before diagnosis/entry into the study were estimated using measurements from the California Air Resources Board monitor closest to the participant's residence. In single-pollutant adjusted conditional logistic regression models, the pulmonary TB odds ratios (95% confidence intervals) for the highest quintile (vs. lowest) were 1.50 (95% CI: 1.15, 1.95) for CO and 1.42 (95% CI: 1.10, 1.84) for NO2. Corresponding estimates were higher among never [1.68 (95% CI: 1.26, 2.24)] than ever [1.19 (95% CI: 0.74, 1.92)] smokers for CO. In contrast, for NO2, estimates were higher among ever [1.81 (95% CI: 1.13, 2.91)] than never [1.29 (95% CI: 0.97, 1.71)] smokers. O3 was inversely associated for smokers [0.66 (95% CI: 0.43, 1.02)] and never smokers [0.65 (95% CI: 0.52, 0.81)]. No other consistent patterns were observed. In this first, to our knowledge, U.S. nested case-control study on air pollution and pulmonary TB, we observed positive associations with ambient CO and NO2, which require confirmation. Smith GS, Van Den Eeden SK, Garcia C, Shan J, Baxter R, Herring AH, Richardson DB, Van Rie A, Emch M, Gammon MD. 2016. Air pollution and pulmonary tuberculosis: a nested case-control

An alternative experimental case-control design for genetic association studies on bovine mastitis.

PubMed

Biffani, S; Del Corvo, M; Capoferri, R; Pedretti, A; Luini, M; Williams, J L; Pagnacco, G; Minvielle, F; Minozzi, G

2017-04-01

The possibility of using genetic control strategies to increase disease resistance to infectious diseases relies on the identification of markers to include in the breeding plans. Possible incomplete exposure of mastitis-free (control) animals, however, is a major issue to find relevant markers in genetic association studies for infectious diseases. Usually, designs based on elite dairy sires are used in association studies, but an epidemiological case-control strategy, based on cows repeatedly field-tested could be an alternative for disease traits. To test this hypothesis, genetic association results obtained in the present work from a cohort of Italian Holstein cows tested for mastitis over time were compared with those from a previous genome-wide scan on Italian Holstein sires genotyped with 50k single nucleotide polymorphisms for de-regressed estimated breeding values for somatic cell counts (SCCs) on Bos taurus autosome (BTA6) and BTA14. A total of 1121 cows were selected for the case-control approach (cases=550, controls=571), on a combination of herd level of SCC incidence and of within herd individual level of SCC. The association study was conducted on nine previously identified markers, six on BTA6 and four on BTA14, using the R statistical environment with the 'qtscore' function of the GenABEL package, on high/low adjusted linear score as a binomial trait. The results obtained in the cow cohort selected on epidemiological information were in agreement with those obtained from the previous sire genome-wide association study (GWAS). Six out of the nine markers showed significant association, four on BTA14 (rs109146371, rs109234250, rs109421300, rs109162116) and two on BTA6 (rs110527224 and rs42766480). Most importantly, using mastitis as a case study, the current work further validated the alternative use of historical field disease data in case-control designs for genetic analysis of infectious diseases in livestock.

Functional Impairment in Adult Sleepwalkers: A Case-Control Study

PubMed Central

Lopez, Regis; Jaussent, Isabelle; Scholz, Sabine; Bayard, Sophie; Montplaisir, Jacques; Dauvilliers, Yves

2013-01-01

Study Objectives: To investigate the restorative quality of sleep and daytime functioning in sleepwalking adult patients in comparison with controls. Design: Prospective case-control study. Setting: Data were collected at the Sleep Disorders Center, Hôpital-Gui-de Chauliac, Montpellier, France between June 2007 and January 2011. Participants: There were 140 adult sleepwalkers (100 (median age 30 y, 55% male) in whom primary SW was diagnosed) who underwent 1 night of video polysomnography. All patients participated in a standardized clinical interview and completed a battery of questionnaires to assess clinical characteristics of parasomnia, daytime sleepiness, fatigue, insomnia, depressive and anxiety symptoms, and health-related quality of life. Results were compared with those of 100 sex- and age-matched normal controls. Interventions: N/A. Measurements and Results: Of the sleepwalkers, 22.3% presented with daily episodes and 43.5% presented with weekly episodes. Median age at sleepwalking onset was 9 y. Familial history of sleepwalking was reported in 56.6% of sleepwalkers and violent sleep related behaviors in 57.9%, including injuries requiring medical care for at least one episode in 17%. Significant associations were found between sleepwalking and daytime sleepiness, fatigue, insomnia, depressive and anxiety symptoms, and altered quality of life. Early-onset sleepwalkers had higher frequency of violent behaviors and injuries. Sleepwalkers with violent behaviors had higher frequency of sleep terrors and triggering factors, with greater alteration in health-related quality of life. Conclusion: Adult sleepwalking is a potentially serious condition that may induce violent behaviors, self-injury or injury to bed partners, sleep disruption, excessive daytime sleepiness, fatigue, and psychological distress, all of which affect health-related quality of life. Citation: Lopez R; Jaussent I; Scholz S; Bayard S; Montplaisir J; Dauvilliers Y. Functional impairment in

Estimating risk and rate levels, ratios and differences in case-control studies.

PubMed

King, Gary; Zeng, Langche

2002-05-30

Classic (or 'cumulative') case-control sampling designs do not admit inferences about quantities of interest other than risk ratios, and then only by making the rare events assumption. Probabilities, risk differences and other quantities cannot be computed without knowledge of the population incidence fraction. Similarly, density (or 'risk set') case-control sampling designs do not allow inferences about quantities other than the rate ratio. Rates, rate differences, cumulative rates, risks, and other quantities cannot be estimated unless auxiliary information about the underlying cohort such as the number of controls in each full risk set is available. Most scholars who have considered the issue recommend reporting more than just risk and rate ratios, but auxiliary population information needed to do this is not usually available. We address this problem by developing methods that allow valid inferences about all relevant quantities of interest from either type of case-control study when completely ignorant of or only partially knowledgeable about relevant auxiliary population information.

Internet-based control recruitment for a case-control study of major risk factors for stroke in Korea: lessons from the experience.

PubMed

Park, Jong-Moo; Cho, Yong-Jin; Lee, Kyung Bok; Park, Tai Hwan; Lee, Soo Joo; Han, Moon-Ku; Ko, Youngchai; Lee, Jun; Cha, Jae-Kwan; Lee, Byung-Chul; Yu, Kyung-Ho; Oh, Mi-Sun; Lee, Ji Sung; Lee, Juneyoung; Bae, Hee-Joon

2014-01-01

This study aimed to estimate the population-attributable risks (PARs) of 9 major risk factors for stroke in Korea through a case-control study and to test the feasibility and validity of internet-based control recruitment. From April 2008 to September 2009, controls were enrolled via internet after providing consent for participation through a web-based survey. The cases included patients who were admitted to the participating centers due to acute stroke or transient ischemic attack within 7 days of onset during the study period. Each control was age- and sex-matched with 2 cases. Adjusted odd ratios, age-standardized prevalence, and PARs were estimated for the 9 major risk factors using the prevalence of risk factors in the control group and the age and sex characteristics from Korea's national census data. In total, 1041 controls were matched to 2082 stroke cases. Because of a shortage of elderly controls in the internet-based recruitment, 248 controls were recruited off-line. The PARs were 23.44%, 10.95%, 51.32%, and 6.35% for hypertension, diabetes, smoking, and stroke history, respectively. Hypercholesterolemia, atrial fibrillation, obesity, coronary heart disease, and a family history of stroke were not associated with stroke. Comparison with education and religion of the control group with that mentioned in the national census data showed a notable difference. The study results imply that internet-based control recruitment for a case-control study requires careful selection of risk factors with high self-awareness and effective strategies to facilitate the recruitment of elderly participants. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Tumor-based case-control studies of infection and cancer: muddling the when and where of molecular epidemiology.

PubMed

Engels, Eric A; Wacholder, Sholom; Katki, Hormuzd A; Chaturvedi, Anil K

2014-10-01

We describe the "tumor-based case-control" study as a type of epidemiologic study used to evaluate associations between infectious agents and cancer. These studies assess exposure using diseased tissues from affected individuals (i.e., evaluating tumor tissue for cancer cases), but they must utilize nondiseased tissues to assess control subjects, who do not have the disease of interest. This approach can lead to exposure misclassification in two ways. First, concerning the "when" of exposure assessment, retrospective assessment of tissues may not accurately measure exposure at the key earlier time point (i.e., during the etiologic window). Second, concerning the "where" of exposure assessment, use of different tissues in cases and controls can have different accuracy for detecting the exposure (i.e., differential exposure misclassification). We present an example concerning the association of human papillomavirus with various cancers, where tumor-based case-control studies likely overestimate risk associated with infection. In another example, we illustrate how tumor-based case-control studies of Helicobacter pylori and gastric cancer underestimate risk. Tumor-based case-control studies can demonstrate infection within tumor cells, providing qualitative information about disease etiology. However, measures of association calculated in tumor-based case-control studies are prone to over- or underestimating the relationship between infections and subsequent cancer risk. ©2014 American Association for Cancer Research.

Premalignant gastric lesions in patients with gastric mucosa-associated lymphoid tissue lymphoma and metachronous gastric adenocarcinoma: a case-control study.

PubMed

Capelle, Lisette G; den Hoed, Caroline M; de Vries, Annemarie C; Biermann, Katharina; Casparie, Mariel K; Meijer, Gerrit A; Kuipers, Ernst J

2012-01-01

Patients with gastric mucosa-associated lymphoid tissue lymphoma or diffuse large B-cell lymphoma have an increased risk of developing gastric carcinoma (GC). Identifying patients at high GC risk may lead to improved survival and prognosis. The aim of this case-control study was to evaluate whether premalignant gastric lesions are more prevalent and severe in gastric lymphoma (GL) patients with a subsequent diagnosis of GC than in those without GC. Patients with a first GL diagnosis from 1991-2008 were identified in the Dutch histopathology registry (PALGA). Cases were patients with a diagnosis of GL and a subsequent diagnosis of GC. Controls were patients with a diagnosis of GL without GC development. In total, eight cases (mean follow-up 5.5 years) and 31 controls (mean follow-up 5.3 years) were included (mean age 60 years). At lymphoma diagnosis, six (75%) cases were diagnosed with premalignant lesions, whereas in the control group, 21 (68%) had histological evidence for premalignant lesions (P=0.69). At GC diagnosis, five (63%) cases showed intestinal metaplasia in the surrounding gastric mucosa. In 22 (71%) controls premalignant lesions were present at the end of follow-up (P=0.47). No differences were demonstrated in the prevalence of premalignant lesions of cases and controls at GL diagnosis or the end of follow-up. As the prevalence of premalignant lesions is substantial in both the groups of patients, careful endoscopic surveillance of GL patients is warranted not only for recurrence of lymphoma, but also for progression to adenocarcinoma.

Antioxidants and breast cancer risk- a population-based case-control study in Canada

PubMed Central

2011-01-01

Background The effect of antioxidants on breast cancer is still controversial. Our objective was to assess the association between antioxidants and breast cancer risk in a large population-based case-control study. Methods The study population included 2,362 cases with pathologically confirmed incident breast cancer (866 premenopausal and 1,496 postmenopausal) and 2,462 controls in Canada. Intakes of antioxidants from diet and from supplementation as well as other potential risk factors for breast cancer were collected by a self-reported questionnaire. Results Compared with subjects with no supplementation, 10 years or longer supplementation of zinc had multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI) of 0.46 (0.25-0.85) for premenopausal women, while supplementation of 10 years or longer of multiple vitamin, beta-carotene, vitamin C, vitamin E and zinc had multivariable-adjusted ORs (95% CIs) of 0.74 (0.59, 0.92), 0.58 (0.36, 0.95), 0.79 (0.63-0.99), 0.75 (0.58, 0.97), and 0.47 (0.28-0.78), respectively, for postmenopausal women. No significant effect of antioxidants from dietary sources (including beta-carotene, alpha-carotene, lycopene, lutein and zeaxanthin, vitamin C, vitamin E, selenium and zinc) or from supplementation less than 10 years was observed. Conclusions This study suggests that supplementation of zinc in premenopausal women, and supplementation of multiple vitamin, beta-carotene, vitamin C, vitamin E and zinc in postmenopausal women for 10 or more years may protect women from developing breast cancer. However, we were unable to determine the overall effect of total dose or intake from both diet and supplement. PMID:21864361

Stability analysis via the concept of Lyapunov exponents: a case study in optimal controlled biped standing

NASA Astrophysics Data System (ADS)

Sun, Yuming; Wu, Christine Qiong

2012-12-01

Balancing control is important for biped standing. In spite of large efforts, it is very difficult to design balancing control strategies satisfying three requirements simultaneously: maintaining postural stability, improving energy efficiency and satisfying the constraints between the biped feet and the ground. In this article, a proportional-derivative (PD) controller is proposed for a standing biped, which is simplified as a two-link inverted pendulum with one additional rigid foot-link. The genetic algorithm (GA) is used to search for the control gain meeting all three requirements. The stability analysis of such a deterministic biped control system is carried out using the concept of Lyapunov exponents (LEs), based on which, the system stability, where the disturbance comes from the initial states, and the structural stability, where the disturbance comes from the PD gains, are examined quantitively in terms of stability region. This article contributes to the biped balancing control, more significantly, the method shown in the studied case of biped provides a general framework of systematic stability analysis for certain deterministic nonlinear dynamical systems.

Vitamin C Intake and Pancreatic Cancer Risk: A Meta-Analysis of Published Case-Control and Cohort Studies.

PubMed

Hua, Yong-Fei; Wang, Gao-Qing; Jiang, Wei; Huang, Jing; Chen, Guo-Chong; Lu, Cai-De

2016-01-01

Observational studies inconsistently reported the relationship between vitamin C intake and risk of pancreatic cancer. We conducted a meta-analysis of published case-control and cohort studies to quantify the association. Potentially eligible studies were found on PubMed and EMBASE databases through May 31, 2015. A random-effects model was assigned to compute summary point estimates with corresponding 95% confidence intervals (CIs). Subgroup and meta-regression analyses were also performed to explore sources of heterogeneity. Our final analyses included 20 observational studies comprising nearly 5 thousand cases of pancreatic cancer. When comparing the highest with the lowest categories of vitamin C intake, the summary odds ratio/relative risk for case-control studies (14 studies), cohort studies (6 studies) and all studies combined was 0.58 (95% CI: 0.52-0.66), 0.93 (95% CI: 0.78-1.11) and 0.66 (95% CI: 0.58-0.75), respectively. The difference in the findings between case-control and cohort studies was statistically significant (P < .001). Possible publication bias was shown in the meta-analysis of case-control studies. There is insufficient evidence to conclude any relationship between vitamin C intake and risk of pancreatic cancer. The strong inverse association observed in case-control studies may be affected by biases (eg, recall and selection biases) that particularly affect case-control studies and/or potential publication bias. Future prospective studies of vitamin C intake and pancreatic cancer are needed.

Recall bias in melanoma risk factors and measurement error effects: a nested case-control study within the Norwegian Women and Cancer Study.

PubMed

Parr, Christine L; Hjartåker, Anette; Laake, Petter; Lund, Eiliv; Veierød, Marit B

2009-02-01

Case-control studies of melanoma have the potential for recall bias after much public information about the relation with ultraviolet radiation. Recall bias has been investigated in few studies and only for some risk factors. A nested case-control study of recall bias was conducted in 2004 within the Norwegian Women and Cancer Study: 208 melanoma cases and 2,080 matched controls were invited. Data were analyzed for 162 cases (response, 78%) and 1,242 controls (response, 77%). Questionnaire responses to several host factors and ultraviolet exposures collected at enrollment in 1991-1997 and in 2004 were compared stratified on case-control status. Shifts in responses were observed among both cases and controls, but a shift in cases was observed only for skin color after chronic sun exposure, and a larger shift in cases was observed for nevi. Weighted kappa was lower for cases than for controls for most age intervals of sunburn, sunbathing vacations, and solarium use. Differences in odds ratio estimates of melanoma based on prospective and retrospective measurements indicate measurement error that is difficult to characterize. The authors conclude that indications of recall bias were found in this sample of Norwegian women, but that the results were inconsistent for the different exposures.

Epstein-Barr Virus and Gastric Cancer Risk: A Meta-analysis With Meta-regression of Case-control Studies.

PubMed

Bae, Jong-Myon; Kim, Eun Hee

2016-03-01

Research on how the risk of gastric cancer increases with Epstein-Barr virus (EBV) infection is lacking. In a systematic review that investigated studies published until September 2014, the authors did not calculate the summary odds ratio (SOR) due to heterogeneity across studies. Therefore, we include here additional studies published until October 2015 and conduct a meta-analysis with meta-regression that controls for the heterogeneity among studies. Using the studies selected in the previously published systematic review, we formulated lists of references, cited articles, and related articles provided by PubMed. From the lists, only case-control studies that detected EBV in tissue samples were selected. In order to control for the heterogeneity among studies, subgroup analysis and meta-regression were performed. In the 33 case-control results with adjacent non-cancer tissue, the total number of test samples in the case and control groups was 5280 and 4962, respectively. In the 14 case-control results with normal tissue, the total number of test samples in case and control groups was 1393 and 945, respectively. Upon meta-regression, the type of control tissue was found to be a statistically significant variable with regard to heterogeneity. When the control tissue was normal tissue of healthy individuals, the SOR was 3.41 (95% CI, 1.78 to 6.51; I-squared, 65.5%). The results of the present study support the argument that EBV infection increases the risk of gastric cancer. In the future, age-matched and sex-matched case-control studies should be conducted.

Comorbidities in rotator cuff disease: a case-control study.

PubMed

Titchener, Andrew G; White, Jonathan J E; Hinchliffe, Sally R; Tambe, Amol A; Hubbard, Richard B; Clark, David I

2014-09-01

Rotator cuff disease is a common condition in the general population, but relatively little is known about its associated risk factors. We have undertaken a large case-control study using The Health Improvement Network database to assess and to quantify the relative contributions of some constitutional and environmental risk factors for rotator cuff disease in the community. Our data set included 5000 patients with rotator cuff disease who were individually matched with a single control by age, sex, and general practice (primary care practice). The median age at diagnosis was 55 years (interquartile range, 44-65 years). Multivariate analysis showed that the risk factors associated with rotator cuff disease were Achilles tendinitis (odds ratio [OR] = 1.78), trigger finger (OR = 1.99), lateral epicondylitis (OR = 1.71), and carpal tunnel syndrome (OR = 1.55). Oral corticosteroid therapy (OR = 2.03), oral antidiabetic use (OR = 1.66), insulin use (OR = 1.77), and "overweight" body mass index of 25.1 to 30 (OR = 1.15) were also significantly associated. Current or previous smoking history, body mass index of greater than 30, any alcohol intake, medial epicondylitis, de Quervain syndrome, cubital tunnel syndrome, and rheumatoid arthritis were not found to be associated with rotator cuff disease. We have identified a number of comorbidities and risk factors for rotator cuff disease. These include lateral epicondylitis, carpal tunnel syndrome, trigger finger, Achilles tendinitis, oral corticosteroid use, and diabetes mellitus. The findings should alert the clinician to comorbid pathologic processes and guide future research into the etiology of this condition. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Shape control of large space structures

NASA Technical Reports Server (NTRS)

Hagan, M. T.

1982-01-01

A survey has been conducted to determine the types of control strategies which have been proposed for controlling the vibrations in large space structures. From this survey several representative control strategies were singled out for detailed analyses. The application of these strategies to a simplified model of a large space structure has been simulated. These simulations demonstrate the implementation of the control algorithms and provide a basis for a preliminary comparison of their suitability for large space structure control.

Intrahousehold resource allocation and child growth in Mozambique: an ethnographic case-control study.

PubMed

Pfeiffer, J; Gloyd, S; Ramirez Li, L

2001-07-01

This study examines the effect of intrahousehold cash income control and decision-making patterns on child growth in the rural town of Sussundenga in Manica Province, Mozambique. A case-control study design was used to examine the influence of men's and women's disaggregated cash incomes on child growth. The research tested whether greater maternal share of household cash income was associated with (1) increased maternal decision-making and bargaining power in the household, and (2) better child growth. Fifty case households, with children 1-4 years old exhibiting poor growth, were matched with 50 control households of similar socioeconomic status in which all children under five demonstrated healthy growth. Data were gathered on gender-specific income generation and expenditure, specific intrahousehold allocation processes, diet, and sociodemographic variables using a formal survey. Key informant interviews, focus groups, and observation over one year provided ethnographic context for the case-control findings. Case-control differences were analyzed using McNemar's test, paired t-test, and conditional logistic regression. In spite of matching households for socioeconomic status, control household incomes were still slightly greater than cases. Male spouse income was also higher among controls while maternal income, and maternal proportion of household income, were not significantly different. Household meat, fish and poultry consumption, and maternal education were significantly greater among control households than cases. Greater maternal share of household income was not associated with greater maternal decision-making around cash. However, mothers must spend what little cash they earn on daily food supplies and usually request additional cash from spouses to cover these costs. There is evidence that if mothers earn enough to cover these socially prescribed costs, they can spend cash for other needs. Above this threshold, women's earnings may confer more

Zinc Intake and Risk of Prostate Cancer: Case-Control Study and Meta-Analysis.

PubMed

Mahmoud, Abeer M; Al-Alem, Umaima; Dabbous, Firas; Ali, Mohamed M; Batai, Ken; Shah, Ebony; Kittles, Rick A

2016-01-01

Zinc is an essential dietary element that has been implicated in the pathogenesis of prostate cancer, a cancer that disproportionately affects men of African descent. Studies assessing the association of zinc intake and prostate cancer have yielded inconsistent results. Furthermore, very little is known about the relationship between zinc intake and prostate cancer among African Americans. We examined the association between self-reported zinc intake and prostate cancer in a hospital-based case-control study of African Americans. We then compared our results with previous studies by performing a meta-analysis to summarize the evidence regarding the association between zinc and prostate cancer. Newly diagnosed African American men with histologically confirmed prostate cancer (n = 127) and controls (n = 81) were recruited from an urban academic urology clinic in Washington, DC. Controls had higher zinc intake, with a mean of 14 mg/day versus 11 mg/day for cases. We observed a non-significant, non-linear increase in prostate cancer when comparing tertiles of zinc intake (OR <6.5 vs 6.5-12.5mg/day 1.8, 95% CI: 0.6,5.6; OR <6.5 vs >12.5mg/day 1.3, 95% CI: 0.2,6.5). The pooled estimate from 17 studies (including 3 cohorts, 2 nested case-control, 11 case-control studies, and 1 randomized clinical trial, with a total of 111,199 participants and 11,689 cases of prostate cancer) was 1.07hi vs lo 95% CI: 0.98-1.16. Using a dose-response meta-analysis, we observed a non-linear trend in the relationship between zinc intake and prostate cancer (p for nonlinearity = 0.0022). This is the first study to examine the relationship between zinc intake in black men and risk of prostate cancer and systematically evaluate available epidemiologic evidence about the magnitude of the relationship between zinc intake and prostate cancer. Despite of the lower intake of zinc by prostate cancer patients, our meta-analysis indicated that there is no evidence for an association between zinc

Risk factors for syphilis in women: case-control study

PubMed Central

de Macêdo, Vilma Costa; de Lira, Pedro Israel Cabral; de Frias, Paulo Germano; Romaguera, Luciana Maria Delgado; Caires, Silvana de Fátima Ferreira; Ximenes, Ricardo Arraes de Alencar

2017-01-01

ABSTRACT OBJECTIVE To determine the sociodemographic, behavioral, and health care factors related to the occurrence of syphilis in women treated at public maternity hospitals. METHODS This is a case-control study (239 cases and 322 controls) with women admitted to seven maternity hospitals in the municipality of Recife, Brazil, from July 2013 to July 2014. Eligible women were recruited after the result of the VDRL (Venereal Disease Research Laboratory) under any titration. The selection of cases and controls was based on the result of the serology for syphilis using ELISA (enzyme-linked immunosorbent assay). The independent variables were grouped into: sociodemographic, behavioral, clinical and obstetric history, and health care in prenatal care and maternity hospital. Information was obtained by interview, during hospitalization, with the application of a questionnaire. Odds ratios and 95% confidence intervals were estimated using logistic regression to identify the predicting factors of the variable to be explained. RESULTS The logistic regression analysis identified as determinant factors for gestational syphilis: education level of incomplete basic education or illiterate (OR = 2.02), lack of access to telephone (OR = 2.4), catholic religion (OR = 1.70 ), four or more pregnancies (OR = 2.2), three or more sexual partners in the last year (OR = 3.1), use of illicit drugs before the age of 18 (OR = 3.0), and use of illicit drugs by the current partner (OR = 1.7). Only one to three prenatal appointments (OR = 3.5) and a previous history of sexually transmitted infection (OR = 9.7) were also identified as determinant factors. CONCLUSIONS Sociodemographic, behavioral, and health care factors are associated with the occurrence of syphilis in women and should be taken into account in the elaboration of universal strategies aimed at the prevention and control of syphilis, but with a focus on situations of greater vulnerability. PMID:28832758

Control selection and confounding factors: A lesson from a Japanese case-control study to examine acellular pertussis vaccine effectiveness.

PubMed

Ohfuji, Satoko; Okada, Kenji; Nakano, Takashi; Ito, Hiroaki; Hara, Megumi; Kuroki, Haruo; Hirota, Yoshio

2017-08-24

When using a case-control study design to examine vaccine effectiveness, both the selection of control subjects and the consideration of potential confounders must be the important issues to ensure accurate results. In this report, we described our experience from a case-control study conducted to evaluate the effectiveness of acellular pertussis vaccine combined with diphtheria-tetanus toxoids (DTaP vaccine). Newly diagnosed pertussis cases and age- and sex-matched friend-controls were enrolled, and the history of DTaP vaccination was compared between groups. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) of vaccination for development of pertussis. After adjustment for potential confounders, four doses of DTaP vaccination showed a lower OR for pediatrician-diagnosed pertussis (OR=0.11, 95% CI, 0.01-0.99). In addition, the decreasing OR of four doses vaccination was more pronounced for laboratory-confirmed pertussis (OR=0.07, 95%CI, 0.01-0.82). Besides, positive association with pertussis was observed in subjects with a history of steroid treatment (OR=5.67) and those with a recent contact with a lasting cough (OR=4.12). When using a case-control study to evaluate the effectiveness of vaccines, particularly those for uncommon infectious diseases such as pertussis, the use of friend-controls may be optimal due to the fact that they shared a similar experience for exposure to the pathogen as the cases. In addition, to assess vaccine effectiveness as accurately as possible, the effects of confounding should be adequately controlled with a matching or analysis technique. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Cutaneous sarcoidosis: A retrospective case series and a hospital-based case-control study in Taiwan.

PubMed

Liu, Kwei-Lan; Tsai, Wen-Chien; Lee, Chih-Hung

2017-10-01

Sarcoidosis is a systemic granulomatous disorder of unknown etiology often involving skin. Studies on cutaneous sarcoidosis and comorbidities are limited. This study is aimed to describe the clinical features of cutaneous sarcoidosis diagnosed in our hospital and to determine the relationships between cutaneous sarcoidosis and comorbidities.This retrospective study evaluates patients with cutaneous sarcoidosis in a tertiary center in Taiwan from 1996 to 2015. The records of 38 patients with cutaneous sarcoidosis were reviewed for clinical characteristics and evaluated by analysis of variance. A 1:4 case-control analysis was conducted with 152 age- and sex-matched controls who underwent biopsy for other benign skin tumors.The male to female ratio was 1:4.4. The average age at diagnosis was 51.7 years. Female patients were on average 13.9 years older than male patients. The correlation of age with gender was statistically significant (P = .037). The most common cutaneous lesions were plaques (47.4%) and confined to the face (71.1%). Of the 38 patients, 26.3% had diabetes mellitus. Age over 40 (P = .014) and female (P = .014) were associated with facial involvement. In the case-control study, a higher percentage of patients with cutaneous sarcoidosis than of control subjects had diabetes mellitus (P = .001), hearing loss (P = .031) and eye diseases (P = .047).The present study demonstrates a striking female predominance and high proportions of facial involvement. Diabetes mellitus, hearing loss, and eye diseases may be associated with Taiwanese patients with cutaneous sarcoidosis.

Birth outcomes of cases with isolated atrial septal defect type II--a population-based case-control study.

PubMed

Vereczkey, Attila; Kósa, Zsolt; Csáky-Szunyogh, Melinda; Urbán, Róbert; Czeizel, Andrew E

2013-07-01

In general, epidemiological studies have evaluated cases with congenital cardiovascular abnormalities together. The aim of this study is to describe the birth outcomes of cases with isolated/single atrial septal defect type II (ASD-II, i.e. only a fossa ovalis defect) after surgical correction or lethal outcome in the light of maternal sociodemographic data. Comparison of birth outcomes and maternal characteristics of cases with ASD-II and controls without defect. The population-based Hungarian Case-Control Surveillance of Congenital Abnormalities. Hungarian newborn infants with or without ASD-II. Medically recorded birth outcomes, maternal age and birth order were evaluated. Marital and employment status was based on maternal information. The lifestyle factors were analyzed in a subsample of mothers visited at home based on a personal interview with mothers and their close relatives, and the family consensus was accepted. Mean gestational age at delivery and birthweight, rate of preterm birth and low birthweight, maternal age, birth order, marital and employment status. The evaluation of 471 cases with ASD-II and 38,151 controls without any defects showed a female excess in cases with ASD-II, having shorter gestational age and lower mean birthweight, and thus a higher rate of preterm births and low birthweight. Intrauterine growth restriction and shorter gestational age were found in cases with ASD-II, particularly in female children. These factors may have a general developmental process in which there was not closure of the foramen ovale, thus echocardiographic screening of these babies might be of value. © 2012 The Authors Acta Obstetricia et Gynecologica Scandinavica © 2012 Nordic Federation of Societies of Obstetrics and Gynecology.

Effectiveness of inactivated quadrivalent influenza vaccine in the 2015/2016 season as assessed in both a test-negative case-control study design and a traditional case-control study design.

PubMed

Kimiya, Takahisa; Shinjoh, Masayoshi; Anzo, Makoto; Takahashi, Hiroki; Sekiguchi, Shinichiro; Sugaya, Norio; Takahashi, Takao

2018-04-21

Both traditional case-control studies (TCCSs) and test-negative case-control studies (TNCCSs) are commonly used to assess influenza vaccine effectiveness (VE). To compensate for the fact that observational studies are susceptible to bias, we combined both methods to assess VE in one geographical area during the 2015/2016 season, when influenza A (H1N1)pdm was dominant. Our TNCCS covered 331 children aged 6 months to 15 years who visited our hospital with fever, including 182 with influenza, and our TCCS covered 812 pediatric outpatients aged 6 months to 15 years, including 214 with influenza. Influenza infection and vaccination history were reviewed, and VE was calculated as (1 - odds ratio) × 100. In the TNCCS, VE against influenza A was 68% (95% CI 47-81) overall, and 70% (48-83) for those given two doses; against influenza B, VE was 37% (- 12-64) overall and 49% (2-74) for two doses. In the TCCS, VE against influenza A was 44% (15-63) overall and 44% (13-64) for two doses, and VE against influenza B was 24% (- 19-52) overall and 41% (3-64) for two doses. Both studies confirmed significant VE against influenza A, significant two-dose VE against influenza B, and better two-dose VE than one-dose VE. What is Known: • Influenza vaccine effectiveness (VE) varies from year to year. • Observational studies are conventionally used for VE assessment. However, they are inherently susceptible to bias and confounding. What is New: • This is the first report of influenza VE assessment using more than one observational study and performed in a specific area during the same season. • VE estimates obtained in our traditional case-control study were lower than those in our test-negative case-control study, but both studies found significant VE against influenza.

The case-control design in veterinary sciences: A survey.

PubMed

Cullen, Jonah N; Sargeant, Jan M; Makielski, Kelly M; O'Connor, Annette M

2016-11-01

The case-control study design is deceptively simple. However, many design considerations influence the estimated effect measure. An investigation of case-control studies in the human health literature suggested that some of these considerations are not described in reports of case-control studies. Our hypothesis was that the majority of veterinary studies labeled as case-controls would be incident density designs, and many would not interpret the effect measure obtained from those studies as the rate ratio rather than the odds ratio. Reference databases were searched for author-designated case-control studies. A survey of 100 randomly selected studies was conducted to examine the different design options described and estimated effect measures. Of the 100 author-identified case-control studies, 83 assessed an exposure-outcome association and, of those, only 54 (65.1%) sampled the study population based on an outcome and would thus be considered case-control designs. Twelve studies were incidence density designs but none used this terminology. Of the studies that reported an odds ratio as the effect measure, none reported on additional considerations that would have enabled a more interpretable result. This survey indicated many case-control-labeled studies were not case-control designs and among case-control studies, key design aspects were not often described. The absence of information about study design elements and underlying assumptions in case-control studies limits the ability to establish the effect measured by the study and the evidentiary value of the study might be underestimated. Copyright © 2016 Elsevier B.V. All rights reserved.

A unified method for evaluating real-time computer controllers: A case study. [aircraft control

NASA Technical Reports Server (NTRS)

Shin, K. G.; Krishna, C. M.; Lee, Y. H.

1982-01-01

A real time control system consists of a synergistic pair, that is, a controlled process and a controller computer. Performance measures for real time controller computers are defined on the basis of the nature of this synergistic pair. A case study of a typical critical controlled process is presented in the context of new performance measures that express the performance of both controlled processes and real time controllers (taken as a unit) on the basis of a single variable: controller response time. Controller response time is a function of current system state, system failure rate, electrical and/or magnetic interference, etc., and is therefore a random variable. Control overhead is expressed as a monotonically nondecreasing function of the response time and the system suffers catastrophic failure, or dynamic failure, if the response time for a control task exceeds the corresponding system hard deadline, if any. A rigorous probabilistic approach is used to estimate the performance measures. The controlled process chosen for study is an aircraft in the final stages of descent, just prior to landing. First, the performance measures for the controller are presented. Secondly, control algorithms for solving the landing problem are discussed and finally the impact of the performance measures on the problem is analyzed.

Case-controlled clinical and histopathological study of conjunctivochalasis.

PubMed

Francis, I C; Chan, D G; Kim, P; Wilcsek, G; Filipic, M; Yong, J; Coroneo, M T

2005-03-01

Conjunctivochalasis, a secondary cause of the watery eye, is frequently seen in the older age group as an elevation of the bulbar conjunctiva lying along the lateral or central lower lid margin. A prospective, interventional, case-controlled clinical and histopathological study was conducted. The relevant features of 18 patients (29 eyes) who had their conjunctivochalasis resected as part of the surgical management of their watery eye syndrome were examined. In the control group, tissue was obtained from an age matched series of 24 normal subjects undergoing routine cataract surgery. 24 controls (24 specimens) and 18 patients (29 specimens) had conjunctival strip biopsies, taken from the usual lid margin level bulbar conjunctiva in line with the inferior limbus (controls), and the clinically apparent conjunctivochalasis (patients). These were submitted for histological study. 23 of 24 control sections demonstrated normal conjunctival variation. Four of 29 patient specimens demonstrated a chronic non-granulomatous conjunctivitis, while three eyes of the patient group (two patients) demonstrated features of elastosis. Of the four patients who had the inflammatory infiltrates, three had functional nasolacrimal duct obstructions (FNLDOs) and one had a primary acquired nasolacrimal duct obstruction (PANDO). Of the two patients who had elastosis, one had an FNLDO and the other had normal lacrimal drainage and was Jones 1 positive. Six of 18 patients--that is, seven of 29 specimens of conjunctivochalasis demonstrated signs of elastosis or of chronic non-granulomatous inflammation. Clinically, patients had a spectrum of aetiologies of their watery eye syndrome.

Integration of DNA sample collection into a multi-site birth defects case-control study.

PubMed

Rasmussen, Sonja A; Lammer, Edward J; Shaw, Gary M; Finnell, Richard H; McGehee, Robert E; Gallagher, Margaret; Romitti, Paul A; Murray, Jeffrey C

2002-10-01

Advances in quantitative analysis and molecular genotyping have provided unprecedented opportunities to add biological sampling and genetic information to epidemiologic studies. The purpose of this article is to describe the incorporation of DNA sample collection into the National Birth Defects Prevention Study (NBDPS), an ongoing case-control study in an eight-state consortium with a primary goal to identify risk factors for birth defects. Babies with birth defects are identified through birth defects surveillance systems in the eight participating centers. Cases are infants with one or more of over 30 major birth defects. Controls are infants without defects from the same geographic area. Epidemiologic information is collected through an hour-long interview with mothers of both cases and controls. We added the collection of buccal cytobrush DNA samples for case-infants, control-infants, and their parents to this study. We describe here the methods by which the samples have been collected and processed, establishment of a centralized resource for DNA banking, and quality control, database management, access, informed consent, and confidentiality issues. Biological sampling and genetic analyses are important components to epidemiologic studies of birth defects aimed at identifying risk factors. The DNA specimens collected in this study can be used for detection of mutations, study of polymorphic variants that confer differential susceptibility to teratogens, and examination of interactions among genetic risk factors. Information on the methods used and issues faced by the NBDPS may be of value to others considering the addition of DNA sampling to epidemiologic studies.

Rubella outbreak investigation, Gokwe North District, Midlands province, Zimbabwe, 2014 - a case control study.

PubMed

Makoni, Annamercy Chenaimoyo; Chemhuru, Milton; Bangure, Donewell; Gombe, Notion Tafara; Tshimanga, Mufuta

2015-01-01

Rubella is a contagious disease, caused by rubella virus and transmitted via the respiratory route. Rubella in pregnancy may cause Congenital Rubella Syndrome (CRS), characterized by multiple defects to the brain, heart, eyes and ears. Gokwe North experienced an increase in rubella cases from 6 cases (24 June 2014) to 374 cases (12 August 2014). The study was conducted to determine risk factors associated with contracting rubella. A 1:1 unmatched case control study was conducted. A case was a child <15 years, resided in Gokwe North, with maculopapular rash and tested positive for rubella specific IgM or was linked epidemiologically to a laboratory confirmed case. Blood was collected for laboratory diagnosis. An interviewer administered questionnaire was used. Epi Info™ was used to analyze data. Eighty eight cases and 88 controls were recruited, median age for cases was 7 years (Q1 = 4, Q3 = 8) and 6 years (Q1 = 3, Q3 = 9) for controls. Independent risk factors for contracting rubella were; classmate contact (AOR 9.44; (95% CI 4.29-20.77)) and having >3 children in a household (AOR 2.59; 95%CI (1.23-5.42)). Only 10.2% and 6.8% of the caregivers' cases and controls respectively, knew rubella is spread through contact with an infected person (p = 0.57). Majority of caregivers (97.8%) reported to the health facility within two days of onset of rash. Outbreak was driven by contact at school and was spread into the community through school children. Screening and isolation of the sick controlled the outbreak. Routine rubella vaccination could be considered to prevent similar outbreaks.

Balance among Cognitive Control Processes: A Case Study of A Gifted Youth

ERIC Educational Resources Information Center

Urben, Sébastien; Camos, Valérie; Habersaat, Stéphanie; Constanty, Lauriane; Stéphan, Philippe

2018-01-01