Objective: To determine whether the quality of care for common ambulatory conditions is adversely affected when physicians are provided with incentives to limit the use of health services.
Design: Retrospective cohort study over a 2-year period.
Setting: Four group practices that cared for both fee-for-service patients and prepaid patients within a network model health maintenance organization (HMO).
Patients: Equal numbers of prepaid (HMO) and fee-for-service patients were selected by randomly choosing medical records from each group practice: 246 patients with chronic uncomplicated hypertension and 250 women without chronic diseases who received preventive care.
Main outcome measures: Adequate hypertension control was defined as a mean blood pressure of less than 150/90. Adequate preventive care was defined as the provision of blood pressure screening, colon cancer screening, breast cancer screening, and cervical cancer screening within guidelines recommended by the 1989 U.S. Preventive Services Task Force. Resource use was measured by the annual number of visits and tests.
Main results: The adjusted relative odds of HMO patients having controlled hypertension, compared with fee-for-service patients, were 1.82 (95% CI, 1.02 to 3.27). The relative risks of HMO patients receiving preventive care within established guidelines were 1.19 (CI, 0.93 to 1.51) for colon cancer screening, 1.78 (CI, 1.11 to 2.84) for annual breast examinations, 1.75 (CI, 1.08 to 2.84) for biannual mammography, and 1.35 (CI, 1.13 to 1.60) for Papanicolaou smears every 3 years. Prepaid patients had visit rates that were 18% to 22% higher than those of fee-for-service patients.
Conclusions: In the type of network model HMO we studied, the quality and quantity of ambulatory care for HMO patients was equal to or better than that for fee-for-service patients. In this setting, the incentives for physicians to limit resource use may be offset by lack of disincentives for HMO patients to seek care.