A collection of 56 topics with contradictory results in case-control research

This research was done to learn more about the frequency and characteristics of conflicting research in case-control studies. In a survey of the epidemiological and medical literature, we found 56 topics in which the results of a case-control study were in conflict with the results from other studies of the same relationship. Cancer was the associated disease for 30 of the controversial topics. We suggest that much of the disagreement may occur because a set of rigorous scientific principles has not yet been accepted to guide the design or interpretation of case-control research. Consequently, the investigator's 'judgement' is the main precaution against scientific hazards and distortions in the validity of evidence. To correct this deficiency, we propose using the principles of an experimental trial to develop the scientific standards for case-control research.