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Rare variant association on unrelated individuals in case-control studies using aggregation tests Vrije Universiteit Brussel

Simon Boutry, Raphaël Helaers, Tom Lenaerts, Miikka Vikkula

Over the past years, progress made in next-generation sequencing technologies and bioinformatics have sparked a surge in association studies. Especially, genome-wide association studies (GWASs) have demonstrated their effectiveness in identifying disease associations with common genetic variants. Yet, rare variants can contribute to additional disease risk or trait heterogeneity. Because GWASs are underpowered for detecting association with ...

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

Fabiola LA GAMBA, Giovanni Corrao, Silvana Romio, Miriam Sturkenboom, Gianluca Trifiro, Tania Schink, Maria de Ridder
PurposeClustering of patients in databases is usually ignored in one-stage meta-analysis of multi-database studies using matched case-control data. The aim of this study was to compare bias and efficiency of such a one-stage meta-analysis with a two-stage meta-analysis. MethodsFirst, we compared the approaches by generating matched case-control data under 5 simulated scenarios, built by varying: (1) the exposure-outcome association; (2) its ...

Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies KU Leuven

Mike McNamee
OBJECTIVE: Concern exists about possible problems with later-in-life brain health, such as cognitive impairment, mental health problems and neurological diseases, in former athletes. We examined the future risk for adverse health effects associated with sport-related concussion, or exposure to repetitive head impacts, in former athletes. DESIGN: Systematic review. DATA SOURCES: Search of MEDLINE, Embase, Cochrane, CINAHL Plus and SPORTDiscus in ...

Toward the most ideal case-control design with related and unrelated dogs in whole-exome sequencing studies Universiteit Gent

Bart Broeckx, Frank Coopman, Geert Verhoeven, Sarah De Keulenaer, Ellen De Meester, Valérie Bavegems, Pascale Smets, Bernadette Van Ryssen, Filip Van Nieuwerburgh, Dieter Deforce, et al.
With the recent development of whole-exome sequencing enrichment designs for the dog, a novel tool for disease-association studies became available. The aim of disease-association studies is to identify one or a very limited number of putative causal variants or genes from the large pool of genetic variation. To maximize the efficiency of these studies and to provide some directions of what to expect, we evaluated the effect on variant reduction ...

Investigating Hardy-Weinberg equilibrium in case-control or cohort studies or meta-analysis Universiteit Gent KU Leuven

A Ziegler, Kristel Van Steen, S Wellek
Yu et al. (Breast Cancer Res Treat 117:675-677, 2009) recently stated that testing for deviation from Hardy-Weinberg equilibrium (HWE) is necessary to identify systematic genotyping errors in case-control studies. They criticized a meta-analytic study for the deviation from HWE in the case group of one study. The aim of this article is twofold. First, we derive recommendations on how to test for deviations from HWE in different study designs. ...

A web application for sample size and power calculation in case-control microbiome studies KU Leuven Universiteit Gent

Karoline Faust, Jeroen Raes
: When designing a case-control study to investigate differences in microbial composition, it is fundamental to assess the sample sizes needed to detect an hypothesized difference with sufficient statistical power. Our application includes power calculation for (i) a recoded version of the two-sample generalized Wald test of the 'HMP' R-package for comparing community composition, and (ii) the Wilcoxon-Mann-Whitney test for comparing operational ...

Modeling the Complex Exposure History of Smoking in Predicting Bladder Cancer A Pooled Analysis of 15 Case-Control Studies KU Leuven

Eliane Kellen
BACKGROUND: Few studies have modeled smoking histories by combining smoking intensity and duration to show what profile of smoking behavior is associated with highest risk of bladder cancer. This study aims to provide insight into the association between smoking exposure history and bladder cancer risk by modeling both smoking intensity and duration in a pooled analysis. METHODS: We used data from 15 case-control studies included in the bladder ...

Associating sporadic, foodborne illness caused by Shiga toxin-producing Escherichia coli with specific foods : a systematic review and meta-analysis of case-control studies Universiteit Gent

Brecht Devleesschauwer, Sara Monteiro Pires, Ian Young, Alex Gill, Shannon E Majowicz
Shiga toxin-producing Escherichia coli (STEC) infections are a significant public health issue, with foodborne transmission causing >1 million illnesses worldwide each year. We conducted a systematic review and meta-analysis (PROSPERO registry # CRD42017074239), to determine the relative association of different food types with sporadic illnesses caused by STEC. Searches were conducted from 01 August to 30 September 2017, using bibliographic ...

Estimating direct effects in cohort and case-control studies Universiteit Gent

Stijn Vansteelandt
Estimating the effect of an exposure on an outcome, other than through some given mediator, requires adjustment for all risk factors of the mediator that are also associated with the outcome. When these risk factors are themselves affected by the exposure, then standard regression methods do not apply. In this article, I review methods for accommodating this and discuss their limitations for estimating the controlled direct effect (ie, the ...