Design, monitoring, and analysis issues relative to adverse events.

In the clinical development of new drugs for market approval, it is frequently impossible to design trials to provide definitive information about safety--particularly about adverse events. It is possible, however, to design most trials to provide definitive information about efficacy. Efficacy trials with new drugs should therefore be monitored for safety, and the safety profile described within and across trials. Confidence intervals are recommended as the appropriate statistical methodology for doing this. Such intervals provide an interval estimate on the unknown incidences of adverse experiences among patients who could be treated with each regimen, as well as permit a conclusion that two regimens are different.