Impact of Medicare coverage on basic clinical services for previously uninsured adults.

CONTEXT Uninsured adults receive less appropriate care and have more adverse health consequences than insured adults. Longitudinal studies would help to more clearly define the effects of health insurance on health care and health. OBJECTIVE To assess the differential effects of gaining Medicare coverage on use of basic clinical services and medications by previously insured and uninsured adults. DESIGN AND SETTING Household survey data from the nationally representative Health and Retirement Study were used to analyze differences in receipt of basic clinical services by adults in 1996 and 2000, before and after becoming eligible for Medicare at age 65 years. PARTICIPANTS A total of 2203 adults aged 60 to 64 years in 1996 who were classified as continuously uninsured (n = 167), intermittently uninsured (n = 216), or continuously insured (n = 1820) in 1994 and 1996, prior to Medicare eligibility. MAIN OUTCOME MEASURES Individuals' reports of receiving cholesterol testing, mammography (in women), prostate examination (in men), and treatment of arthritis and hypertension in the prior 2 years. RESULTS The difference in cholesterol testing between continuously insured and continuously uninsured adults was significantly reduced after Medicare eligibility (35.4% vs 17.7%; change of -17.7% [95% CI, -29.3% to -6.2%]; P =.003), and the reduction was substantially greater among those with hypertension or diabetes than among other adults (29.2% vs 7.7%; difference of 21.5% [95% CI, 0.2% to 42.9%]; P =.048). Differences in use were similarly reduced after Medicare eligibility for mammography in women (30.3% vs 15.0%; change of -15.3% [95% CI, -29.9% to -0.7%]; P =.04) and prostate examination in men (45.2% vs 20.0%; change of -25.2% [95% CI, -45.4% to -5.1%]; P =.01). Continuously uninsured adults with arthritis reported significantly greater increases in arthritis-related medical visits and limitations of activity than continuously insured adults after Medicare eligibility, but not greater increases in arthritis treatments. Among adults with hypertension, differences in use of antihypertensive medications between continuously uninsured and insured adults were essentially unchanged after Medicare coverage. CONCLUSIONS Previously uninsured adults substantially increased their use of covered basic clinical services but not medications after gaining Medicare coverage. An affordable option through which near-elderly uninsured adults could purchase Medicare coverage might have similar effects.