Medicare home health agency utilization, 1984-1994.

: This study analyzes the determinants of Medicare home health agency (HHA) use in 1984, 1989, and 1994. We estimated a two-part model, modified to adjust for heteroskedasticity, using data from the National Long-Term Care Surveys and the sample members' Medicare claim files. We found an evolving pattern of determinants of Medicare HHA utilization. The rapid increase in use after HHA guideline revisions in 1989 was associated closely with rising importance of limitations in activities of daily living and instrumental activities of daily living as determinants of expected utilization. Our results show little evidence that Medicare home health services substitute for informal home care, though they may reduce the use of skilled nursing facility care.