Minimal sizes of cases with a susceptible genotype and minimal odds ratios among susceptible individuals in case-control studies.

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dc.contributor.authorHamajima, Nobuyukien_US
dc.contributor.authorMutoh, Hironorien_US
dc.contributor.authorEguchi, Hidetakaen_US
dc.contributor.authorHonda, Hiroyukien_US
dc.date.accessioned2009-05-27T17:33:26Z
dc.date.available2009-05-27T17:33:26Z
dc.date.issued2005-04-17en_US
dc.descriptionAsian Pacific Journal of Cancer Prevention.en_US
dc.description.abstractOBJECTIVE: Disease risk elevation due to an environmental factor only for individuals with a susceptible genotype is a typical example of gene-environment interaction. In order to identify risk factors interacting with susceptible genotypes in case-control studies, presumptions on minimal size of cases with the susceptible genotype (S (min)) and odds ratio (OR) among the susceptible individuals (OR(susceptible)) are useful. MODEL: Proportion of exposed cases (P(1)) and OR for whole cases (OR(whole)) statistically detectable in a case-control study can be calculated in a conventional method. P(1) was assumed to be a weighted sum of the exposed among cases with the genotype (P(x)) and cases without the genotype (equal to proportion of the exposed among controls, P(0)), i.e., S P(x) + (1 - S) P0, where S is the size (proportion) of cases with the genotype. For each calculated P(1), S became the minimum (S(min)) in case of P(x) = 1. OR(susceptible) was calculated by {P(x) (1 - P(0))} / {(1 - P(x)) P(0)}. RESULTS: S(min) and OR(susceptible) were listed for the combinations of the above components. For example, a detectable P(1) was 0.638 for P(0)=0.5 in a case-control study with 200 cases (N(1)) and 200 controls (N(0)), when a error of a two-sided test was 0.05 with an 80% of power. In case of P(1)=0.638, OR(whole) was 1.77, producing S(min) = 0.277 for infinite OR(susceptible). It indicates that an environmental factor cannot be detected in case that a high-risk genotype frequency is less than 0.277. INTERPRETATION: If the size of cases with a susceptible genotype is expected to be less than S(min), case-control studies are unlikely to detect a significant OR of the environmental factor.en_US
dc.description.affiliationDepartment of Preventive Medicine / Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan. nhamajim@med.nagoya-u.ac.jpen_US
dc.identifier.citationHamajima N, Mutoh H, Eguchi H, Honda H. Minimal sizes of cases with a susceptible genotype and minimal odds ratios among susceptible individuals in case-control studies. Asian Pacific Journal of Cancer Prevention. 2005 Apr-Jun; 6(2): 165-9en_US
dc.identifier.urihttps://imsear.searo.who.int/handle/123456789/37398
dc.language.isoengen_US
dc.source.urihttps://www.apocp.orgen_US
dc.subject.meshCase-Control Studiesen_US
dc.subject.meshEnvironmenten_US
dc.subject.meshGenetic Markersen_US
dc.subject.meshGenotypeen_US
dc.subject.meshHumansen_US
dc.subject.meshModels, Statisticalen_US
dc.subject.meshOdds Ratioen_US
dc.subject.meshPolymorphism, Geneticen_US
dc.subject.meshResearch Designen_US
dc.subject.meshRisken_US
dc.subject.meshSample Sizeen_US
dc.titleMinimal sizes of cases with a susceptible genotype and minimal odds ratios among susceptible individuals in case-control studies.en_US
dc.typeJournal Articleen_US
dc.typeResearch Support, Non-U.S. Gov'ten_US
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