TO USE OR NOT TO USE THE ODDS RATIO IN EPIDEMIOLOGIC ANALYSES

This paper argues that the use of the odds ratio parameter in epidemio logy needs to be considered with a view to the specific study design a nd the types of exposure and disease data at hand. Frequently, the odd s ratio measure is being used instead of the risk ratio or the inciden ce-proportion ratio in cohort studies or as an estimate for the incide nce-density ratio incase-referent studies. Therefore, the analyses of epidemiologic data have produced biased estimates and the presentation of results has been misleading. However, the odds ratio can be relinq uished as an effect measure for these study designs; and, the applicat ion of the case-base sampling approach permits the incidence ratio and difference measures to be estimated without any untenable assumptions . For the Poisson regression, the odds ratio is not a parameter of int erest; only the risk or rate ratio and difference are relevant. For th e conditional logistic regression in matched case-referent studies, th e odds ratio remains useful, but only when it is interpreted as an est imate of the incidence-density ratio. Thus the odds ratio should, in g eneral, give way to the incidence ratio and difference as the measures of choice for exposure effect in epidemiology.