Conducting multiple-site clinical trials in medical rehabilitation research.

This article examines the distinctive opportunities and challenges of multiple-site clinical trials, as distinguished from trials conducted by a single program. Among the topics discussed are: the role of clinical trials generally in medical rehabilitation research; definitions of "clinical trials" and "multiple site"; the distinction between exploratory and capstone trials; the potential advantages and disadvantages of multiple-site trials; planning issues in terms of sampling designs, the choice of outcome measures, approaches to dealing with intervention fidelity, organizational structures, authorship, and the conduct of collateral studies; and implementation issues in terms of pilot-testing procedures, handling emerging issues, and optimizing communication.