HMO Use of Diagnostic Tests: A Review of the Evidence

This article reviews twenty-four studies that compare health maintenance organization (HMO) use ofdiagnostic testing services tofee-for-service(FFS) use. Diagnosticservices contribute to both the high level and the growth of health care costs. This review of a series of studies is important because any single study is commonly limited to a small set of diagnostic tests and generally provides analysis restricted to one, or afew, HMOs. Combining evidence from each of the studies yields thefollowing conclusions. Relative to FFS enrollees, HMO enrollees receive fewer inpatient diagnostic tests. Evidence concerning HMO utilization of outpatient testing relative to FFS plans, though mixed, tends to suggest that HMOs do not perform more ofthese services and may performfewer for patients with chronic illnesses. Quality of care does not appear to suffer in HMOs despite lower testing rates, suggesting HMOs reduce testing in situations in which the incremental value is small.