Overview of clinical trials in medical rehabilitation: impetuses, challenges, and needed future directions.

The goal of clinical trials is to provide the strongest possible basis for inferring that the observed results of a health-oriented intervention are attributable to that intervention and not to other factors. Particularly strong causal inferences can be drawn from the randomized clinical trial in which participants are assigned on a random basis to either the intervention of interest or to a comparison condition. This article explains the reasons for that contention and explores its implications for medical rehabilitation research. Among the topics discussed are: the role of evidence-based practice in fostering interest in randomized clinical trials; a contextual view of randomized clinical trials that emphasizes strategies of investigation and the goals of particular studies; two key distinctions, efficacy-oriented vs. effectiveness-oriented clinical trials and pragmatic vs. explanatory clinical trials; the sequencing of different study designs, including randomized clinical trials; and needed advances in treatment theory, treatment fidelity, and adherence.