Impact of extending health care coverage to the uninsured.

Changes in use of health services by the uninsured, when covered after health reform, are a key to the costs of reform. From data on persons under age sixty-five in the 1989 National Health Interview Survey, we estimated their expected use of hospitals (excluding obstetric deliveries) and doctor visits, adjusting for age, sex, and self-reported health status. If uninsured persons obtained private coverage distributed by the plan type of other persons in their home regions, nonobstetric hospital days for the formerly uninsured would increase 28 percent, and their visits to physicians' offices would increase 52 percent. If instead the uninsured enrolled entirely in group- or staff-model health maintenance organizations (HMOs) in their home regions, their nonobstetric hospital days would actually decrease 17 percent, and their visits to physicians' offices would increase 60 percent.