The art of quality assessment of RCTs included in systematic reviews

The best evidence on the efficacy of medical interventions is provided by high-quality trials summarized in high-quality systematic reviews or meta-analyses. The methodological quality of studies included in a systematic review can have a substantial impact on the estimates of the treatment effect and therefore on the conclusions of such a review. But what is the empirical evidence to support quality assessment of randomized clinical trials (RCTs)? We elaborate on questions such as: what is the concept of quality of individual studies (RCTs), can quality be measured validly and reliably? Plans for future research on this issue are proposed. (C) 2001 Elsevier Science Inc. All rights reserved.