Beyond randomized clinical trials: applying clinical experience in the treatment of patients with coronary artery disease.

FOUR LARGE randomized controlled trials have compared the results of coronary artery bypass graft surgery (CABG) with medical therapy of coronary artery disease.'4 Although the randomized controlled trial is the most scientifically valid method of comparing therapies, these trials have left unanswered many of the important questions that confront clinicians and patients daily. Furthermore, additional trials will probably not be funded comparing medical and surgical approaches, so that alternative methods must be used to study these therapies. We believe that scrupulous analysis of carefully collected clinical data offers a complementary approach to the randomized controlled trials. Although such trials have generated some consensus about patient management,5'the lessons learned from clinical data bases at Duke, the Seattle Heart Watch,8 the University of Alabama,9 and the Coronary Artery Surgery Study (CASS)10 provide further significant insights into the management of patients with coronary disease. In this essay we will first discuss briefly why randomized controlled trials are not suitable to answer all questions of therapeutic interest. We will then discuss the strengths and limitations of observational approaches. Randomized controlled trials of CABG have four important limitations. First, limited resources have led investigators to focus on particular questions of scientific interest, restricting patient enrollments to relatively small, homogeneous portions of the general population seen in clinical practice. Because of the restricted populations, randomized controlled trials as they have been conducted are limited in their ability to examine

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