Trends in the Quality of Care and Racial Disparities in Medicare Managed Care.

BACKGROUND: Since 1997, all managed-care plans administered by Medicare have reported on quality-of-care measures from the Health Plan Employer Data and Information Set (HEDIS). Studies of early data found that blacks received care that was of lower quality than that received by whites. In this study, we assessed changes over time in the overall quality of care and in the magnitude of racial disparities in nine measures of clinical performance. METHODS: In order to compare the quality of care for elderly white and black beneficiaries enrolled in Medicare managed-care plans who were eligible for at least one of nine HEDIS measures, we analyzed 1.8 million individual-level observations from 183 health plans from 1997 to 2003. For each measure, we assessed whether the magnitude of the racial disparity had changed over time with the use of multivariable models that adjusted for the age, sex, health plan, Medicaid eligibility, and socioeconomic position of beneficiaries on the basis of their area of residence. RESULTS: During the seven-year study period, clinical performance improved on all measures for both white enrollees and black enrollees (P<0.001). The gap between white beneficiaries and black beneficiaries narrowed for seven HEDIS measures (P<0.01). However, racial disparities did not decrease for glucose control among patients with diabetes (increasing from 4 percent to 7 percent, P