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Depending on how it's measured, health plan performance may vary by enrollee ethnicity, education, and income

Performance on the standardized measures used by the Nation's health insurers when computing their scores through the Health Plan Employer Data Set (HEDIS) is influenced by factors such as enrollee schooling, income, and ethnic or racial background, according to a recent study. HEDIS is a reporting tool that monitors how well health plans perform essential medical services. The study was led by researchers at Harvard Medical School and supported by the Agency for Healthcare Research and Quality (HS09473).

These findings are particularly important because health insurance contracting decisions by large employers and other health plan purchasers and plan selection by individual consumers can be influenced by how well a health plan performs on HEDIS measures. The tool, which was developed and is administered by the National Committee for Quality Assurance (NCQA), is commonly used by managed care plans throughout the United States.

Lead author Alan M. Zaslavsky, Ph.D., an Associate Professor in Harvard Medical School's Department of Health Care Policy, and fellow researchers from Harvard, NCQA, and other institutions sought to determine whether the quality of care delivered by health plans varies across different populations. To do this, the researchers looked at how the characteristics of enrollees' neighborhoods were related to outcomes on the HEDIS quality measures.

The investigators found that within each health plan, certain populations from areas with relatively high percentages of residents on welfare or who were black or Hispanic received generally poorer quality of care, while enrollees in urban areas and areas with higher educational levels and more Asian-American residents received consistently better care. Although previous studies have found that minority, low-income, and poorly educated patients under-use essential medical services, what's striking about these findings is that they represent differences among commercially insured patients within the same health plans, according to Dr. Zaslavsky. He also noted that the findings underscore the importance of determining the appropriate role for case-mix adjustment—a method used to make adjustments for the composition of a plan's enrollees to permit a more accurate assessment of quality of care provided by the plan. Dr. Zaslavsky pointed out that further work with more detailed adjustments that go beyond geographic proxies for the characteristics of enrollees will be needed to determine the underlying causes of the variations observed in this study.

The findings are based on data from 112,397 enrollees of 10 managed care plans in different parts of the United States. The study resulted from an AHRQ-funded project—the ongoing development and evaluation of HEDIS measures—led by Harvard's Arnold M. Epstein, M.D., and Paul D. Cleary, Ph.D. The project is part of an AHRQ program to strengthen the science base of quality measurement while expanding the scope and availability of validated, ready-to-use measures.

Details of the study summarized here are in "Impact of sociodemographic case mix on the HEDIS measures of health plan quality," in the October 2000 Medical Care, 38(10), pp. 981-992.

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