Trends in Medicare health maintenance organization enrollment: 1986-93.

This study examines Medicare health maintenance organization (HMO) enrollment under the Tax Equity and Fiscal Responsibility Act (TEFRA) of 1982 (Public Law 97-248) from 1986 to 1993. It shows that there was moderate growth in the number of Medicare beneficiaries participating in the TEFRA risk program, reaching 1 in 20 beneficiaries in 1993. Medicare HMO enrollment is heavily concentrated in a few large plans, resulting in heavy concentrations geographically. California and Florida accounted for over one-third of Medicare HMO enrollees. One-half of the States have no Medicare HMO enrollment and one-fifth of the States have fewer than 15,000 Medicare HMO enrollees.