Health services clinical trials: design, conduct, and cost methodology.

Randomized clinical trials and their developing methodology have had substantial impact on the advancement of medical practice. With the emergence of managed care and increased emphasis on the reduction of medical care expenditures, cost evaluation is now becoming a part of clinical trial research. The papers by Henderson et al. and Manheim that follow address the evolution of health services research, its application to multicenter clinical trials in a major U.S. health-care system, and methods of assessing costs in health services clinical trials.