Cost of medical care in an experimental study of prepaid group and fee for service practice.

Enrollees in an experimental prepaid group practice did use fewer hospital days and more ambulatory services than did control enrollees. In spite of this, however, savings generated from this reduction in hospital utilization were not enough to pay for the increased ambulatory services provided. Mechanisms for cost control must be sought in areas in addition to hospital savings. Two such areas are preventive services of unproved value, and physicians' services costs.