Abstract

Randomized and double-blind clinical trials are widely regarded as the most reliable way of studying the effects of medical interventions. According to received wisdom, if a new drug or treatment is to be accepted in clinical practice, its safety and efficacy must first be demonstrated in such trials. For ethical and scientific reasons, it is generally considered necessary to monitor a trial in various ways as it proceeds and to analyze data as they accumulate. Monitoring and interim analyses are often conducted by a so-called data monitoring committee (DMC), a group of experts independent of both sponsors and investigators. On the basis of DMC recommendations, sponsors sometimes decide to discontinue trials ..