Role of phase IV trials in determining the safety and efficacy of oral contraceptives. Guidelines for evaluation.

The continued evaluation of a new drug after it reaches the general marketplace is of ever-increasing concern for pharmaceutical manufacturers and regulatory agencies. This interest in performance after the drug has come to market has spawned a new type of research, "postmarketing surveillance," or phase IV research. Often when a new drug comes to market, a phase IV trial is implemented to reevaluate the results of previously performed controlled clinical trials. While the primary strength of a phase IV trial is that it gathers a large amount of prospective data on many patients in a short time, this type of study is limited in design as compared to the rigorous, randomized clinical trial required to "prove" efficacy. This paper offers the obstetrician-gynecologist and clinical epidemiologist a 10-point checklist to employ when evaluating phase IV trials involving an oral contraceptive.