Outcomes of patients who participate in randomised controlled trials compared to similar patients receiving similar interventions who do not participate

This review assessed whether there are harmful or beneficial effects from participating in randomised controlled trials (RCTs). The outcomes of patients who participated in RCTs were compared with outcomes of patients who were eligible for the trial and received similar clinical interventions, but did not participate. On average, the outcomes of patients participating and not participating in RCTs were similar, suggesting that participation in RCTs, independent of the effects of the clinical interventions being compared, is unlikely to be harmful. In addition, these results challenge the assertion that the results of RCTs are not applicable to usual clinical practice.