Coverage, care, cost, and outcome

The study by Manning et al¹in this issue ofThe Journalreports findings from the Rand Corporation Health Insurance Experiment, a carefully designed study in which families enrolled at six sites across the country were randomly assigned different cost-sharing insurance plans to cover their health care during a two-year period. The study explored the effects of varying insurance coverages on ambulatory health and mental health care utilization and costs. The study found an inverse relationship between coinsurance level and both any and total use of outpatient mental health care. Subjects with a 95% out-of-pocket coinsurance payment per visit had less than half the probability of using any ambulatory mental health services than those covered for free (no coinsurance) care, and the former averaged less than 43% of the latter's total outpatient mental health expenditures. More surprising is that those subjects who had to pay 95% of their health care