Patterns of stability and change in health use among elderly people. Do service systems leave an imprint on behavior?

Stability and change in patterns of health service use over a 3-year period were determined for a sample of elderly people in an urban area who claimed one of five types of health service provider as a primary source of health care--a hospital, a private physician, a network model health maintenance organization (HMO), a hospital-based group practice program (G-HMO), or a preferred provider organization (PPO). Despite certain differences in use rates for individual services, the total volume of ambulatory service use was equivalent for all five groups as was the relative rank order of use of specific ambulatory services for four of the five groups. People who claimed a hospital as their primary care source had the most unique use patterns over a full range of health care services, characterized by extremely low rates of physician visits and the highest rates of visits to hospital outpatient clinics across three time periods. G-HMO members used health-related services more frequently than did all others. PPO members, at baseline, had lower rates of total and mean hospital days than other source group members except hospital users. People who changed principal source of care during the study period were most likely to report a hospital as their care source initially. Although there is much consistency in hospital and ambulatory use across groups, the persistence of certain use patterns for members of some groups suggests that health care systems can leave an imprint on the health service use of people for whom they provide regular care.