Some Interim Results from a Controlled Trial of Cost Sharing in Health Insurance

A total of 7706 persons are participating in a controlled trial of alternative health-insurance policies. Interim results indicate that persons fully covered for medical services spend about 50 per cent more than do similar persons with income-related catastrophe insurance. Full coverage leads to more people using services and to more services per user. Both ambulatory services and hospital admissions increase. Once patients are admitted to the hospital, however, expenditures per admission do not differ significantly among the experimental insurance plans. In addition, hospital admissions for children do not vary by plan. The income-related cost sharing in the experimental plans affects expenditure by different income groups similarly, but adults' total expenditure varies more than children's. Sufficient data are not available on whether higher use by persons with free care reflects overuse, or whether lower use by those with income-related catastrophe coverage reflects underuse. Both may well be true. (N Engl J Med. 1981; 305:1501–7.) CONTROVERSY over the desirability of cost sharing in health-insurance policies has simmered for decades and has occasionally boiled over, in part because of the meager quantitative evidence about the effects of cost sharing on the demand for services and on patients' health status. The limited information available prompted the federal government to sponsor a controlled trial, which will end in early 1982. Results concerning the effects on health are not yet available; only interim results about the use of services are available. However, in the light of the ongoing debate over the appropriate role — if any — of cost.