Diagnostic test use in different practice settings. A controlled comparison.

Health maintenance organizations (HMOs) have lower than average medical care costs, but the reasons remain controversial. The diagnostic practices of cardiologists from an HMO, a university, and a community were therefore surveyed. First, cardiologists defined indications for coronary bypass surgery and then evaluated randomly selected case summaries of patients with chest pain. After review, the cardiologist rated the need for an exercise thallium scintiscan and for a coronary angiogram in each case. Community cardiologists had the broadest indications for bypass surgery. The HMO cardiologists chose thallium scintigraphy significantly less often than the other two types of cardiologists did. The HMO and university cardiologists both rated the need for coronary angiography significantly lower than did community cardiologists. Physicians in different practice settings therefore recommend costly diagnostic and therapeutic methods differently, even for identical patients.