Managed care plan performance since 1980. A literature analysis

Objective. —To compare the health care utilization, expenditure, quality of care, and satisfaction since 1980 of enrollees in managed care and indemnity plans. Data Sources and Study Selection. —Studies selected met the following criteria: data from 1980 forward, private insurance or Medicare enrollees, a comparison group, a reasonable attempt at statistical adjustment for noncomparable managed care and indemnity plan enrollees, and peer-reviewed findings (with two exceptions). Few studies on preferred provider organization plan performance met the selection criteria. Data Synthesis. —Compared with indemnity plans, health maintenance organization plans had somewhat lower hospital admission rates, 1% to 20% shorter hospital length of stay, the same or more physician office visits per enrollee, less use of expensive procedures and tests, greater use of preventive services, mixed results on outcomes, and somewhat lower enrollee satisfaction with services but higher satisfaction with costs. The evidence does not support the hypothesis that prepaid group practice or staff model health maintenance organizations are more effective than individual practice association or network model health maintenance organizations. Conclusions. —Although this literature analysis found several clear patterns of results, several factors, including unmeasured selection bias, diverse and rapidly changing health plans and local market conditions, and relatively few research results, suggest that generalizations must be made with caution. (JAMA. 1994;271:1512-1519)