Access to care in the Indian Health Service.

The Indian Health Service (IHS) is unique among U.S. private and public health programs in that free comprehensive health services are provided to eligible American Indians and Alaska Natives regardless of their ability to pay. However, resource limitations may compel some eligible persons to go outside of the IHS system to receive health care. Although IHS eligibles have comparatively low rates of private or public health care coverage, and much of this population lives in underserved areas, over half of IHS-eligible persons had some type of out-of-plan use in 1987. Furthermore, services received through private providers appear to supplement those received through IHS-sponsored providers. Overall, persons who use both IHS and non-IHS providers have higher levels of health care use than do those who rely exclusively on the IHS.