Case-control studies and their application to endocrinology

The steps for undertaking the case-control approach to studying potential causal factors (i.e., host or environmental factors) related to diseases or conditions of interest are outlined, together with warnings of the potential pitfalls and biases to be avoided. Guidelines are provided for appropriate selection of cases and controls and for ascertaining and valid exposure or host information. In addition, the elements needed to determine the sample size needed for a case-control study, the approach to the analysis of case-control data, and criteria for assessing whether associations observed in epidemiologic studies are actually causal also are provided. Finally, the strengths and limitations of the case-control approach, compared with the cohort approach, are described. Published studies are cited to provide endocrinologic examples of the methodologies and issues raised by the case-control study approach.