Case-Control Studies = Odds Ratios

Estimating crude or common odds ratios in case-control studies with informatively missing exposure data.

In case-control studies, the crude odds ratio derived from a 2 x 2 table and the common odds ratio adjusted for stratification variables are staple measures of exposure-disease association. While missing exposure data are encountered in the majority of such studies, formal attempts to deal with them are rare, and a complete-case analysis is the norm. Furthermore, the probability that exposure i...

Making sense of odds and odds ratios.

Odds and odds ratios are hard for many clinicians to understand. Odds are the probability of an event occurring divided by the probability of the event not occurring. An odds ratio is the odds of the event in one group, for example, those exposed to a drug, divided by the odds in another group not exposed. Odds ratios always exaggerate the true relative risk to some degree. When the probability...

Mischievous Odds Ratios

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

OBJECTIVE 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 ...

Estimation of cumulative odds ratios.

PURPOSE Standard estimation of ordered odds ratios requires the constraint that the etiologic effects of exposure are homogenous across thresholds of the ordered response. We present a method to relax this often-unrealistic constraint. METHODS The kernel of the proposed method is the expansion of observed data into "person-thresholds." Using standard statistical software, for each subject we ...