Disability outcomes of older medicare HMO enrollees and fee-for-service Medicare beneficiaries

OBJECTIVES: To investigate whether older Medicare beneficiaries enrolled in Medicare risk health maintenance organizations (HMOs) have different rates of disablement than fee-for-service (FFS) beneficiaries. DESIGN: Secondary analysis of annual functional status transitions using the Medicare Current Beneficiary Survey, 1991 to 1996. SETTING: Telephone interviews. PARTICIPANTS: Forty-four thousand seven hundred and sixty-five person-years of annual functional status transitions for noninstitutionalized older Medicare beneficiaries who were either risk HMO enrollees or FFS beneficiaries with or without private supplementary insurance. MEASUREMENTS: Five multinomial legit models were estimated as single-state transition models, with five functional states, death, and censored as outcomes. The probability of being in a certain functional state the following year was specified as a function of individual risk factors and HMO versus FFS supplementary insurance status. RESULTS: Among functionally independent beneficiaries, the odds of becoming disabled in activities of daily living (ADLs) within a year were lower among FFS individuals with supplementary insurance (odds ratios (OR) = 0.67, P < .01) and HMO enrollees (OR = 0.58, P < .01). Among older people who were functionally impaired, neither HMO enrollment nor private supplementary insurance affected the risk of further functional decline or functional improvement. Supplementary insurance, but not HMO enrollment, was associated with lower mortality risk among beneficiaries with functional limitations (OR = 0.65, P < .05) or moderate ADL disability (OR = 0.72, P < .05). CONCLUSION: Medicare risk HMO enrollment and FFS private supplementary insurance convey similar benefits of slowing functional decline and extending life span for nonseverely disabled older people. That no association was found between adverse functional status outcomes and risk HMO enrollment has favorable implications regarding the quality of care of managed care plans.