Projecting the older population of the United States: lessons from the past and prospects for the future.

Projections of future populations are fraught with uncertainties based on past fertility and immigration trends, and assumptions about medical science and lifestyles. The U.S. Census Bureau and the Social Security Administration may be unduly cautious in their assumption that the mortality decline of the past two decades cannot continue; it may be sustained for the next half century. Alternative assumptions about rates of mortality and morbidity all indicate that the needs for health services, institutionalization, and home care of the disabled elderly--especially among the oldest old--will make ever greater relative and absolute demands on the nation's health care resources.