Sufficiency of clinical literature on the appropriate uses of six medical and surgical procedures.

We reviewed the English-language clinical literature on carotid endarterectomy, cholecystectomy, upper gastrointestinal endoscopy, colonoscopy, coronary angiography and coronary artery bypass graft procedure to identify the appropriateness of using these procedures in 1981. Most of the 803 relevant articles and textbooks were published after 1975; about 10% of the 571 research studies were randomized, controlled trials, while two thirds were retrospective studies. Incomplete or contradictory information was available on the indications for and efficacy of using the procedures; almost no data were available on costs and use; data on complications failed to specify patients' symptoms or the relationship between complications and reasons for doing the procedure.