Background: There are wide disparities between blacks and whites in the use of many Medicare services. We studied the effects of race and income on mortality and use of services.
Methods: We linked 1990 census data on median income according to ZIP Code with 1993 Medicare administrative data for 26.3 million beneficiaries 65 years of age or older (24.2 million whites and 2.1 million blacks). We calculated age-adjusted mortality rates and age- and sex-adjusted rates of various diagnoses and procedures according to race and income and computed black:white ratios. The 1993 Medicare Current Beneficiary Survey was used to validate the results and determine rates of immunization against influenza.
Results: For mortality, the black:white ratios were 1.19 for men and 1.16 for women (P<0.001 for both). For hospital discharges, the ratio was 1.14 (P<0.001), and for visits to physicians for ambulatory care it was 0.89 (P<0.001). For every 100 women, there were 26.0 mammograms among whites and 17.1 mammograms among blacks. As compared with mammography rates in the respective most affluent group, rates in the least affluent group were 33 percent lower among whites and 22 percent lower among blacks. The black:white rate ratio was 2.45 for bilateral orchiectomy and 3.64 for amputations of all or part of the lower limb (P<0.001 for both). For every 1000 beneficiaries, there were 515 influenza immunizations among whites and 313 among blacks. As compared with immunization rates in the respective most affluent group, rates in the least affluent group were 26 percent lower among whites and 39 percent lower among blacks. Adjusting the mortality and utilization rates for differences in income generally reduced the racial differences, but the effect was relatively small.
Conclusions: Race and income have substantial effects on mortality and use of services among Medicare beneficiaries. Providing health insurance is not enough to ensure that the program is used effectively and equitably by all beneficiaries.