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Health Plan Performance as Measured by Health Plan Reporting Tool Found to Vary by Enrollee Ethnicity, Education

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Press Release Date: October 5, 2000

Performance on the standardized measures used by the nation's health insurers when computing their scores through the Health Plan Employer Data Set (HEDIS)—the reporting tool that monitors how well health plans perform essential medical services—is influenced by factors such as enrollee schooling, income and ethnic or racial background, according to a new study published in the October issue of the journal, Medical Care. The Harvard Medical School (HMS)-led study was supported by the U.S. Agency for Healthcare Research and Quality (AHRQ).

"This is the first study to measure how variations in the social and demographic characteristics of the membership of managed care plans affect quality performance," said AHRQ Director John M. Eisenberg, M.D.

Dr. Eisenberg said the new evidence is 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 the HMS 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 care, while enrollees in urban areas and areas with higher educational levels and more Asian-American residents received consistently better care.

Dr. Zaslavsky said, "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." The researcher added that the findings underscore the importance of determining the appropriate role for case-mix adjustment—a methodology for adjusting plan scores which attempts to measure the quality of care that plans provide without being affected by the composition of their enrollees. Dr. Zaslavsky also said that further work with more detailed adjustments which 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 today's study are in "Impact of Sociodemographic Case Mix on the HEDIS Measures of Health Plan Quality," in the October 2000 issue of Medical Care.

Editor's Note: For interviews of Dr. Zaslavsky, call John Lacy at (617) 432-0441.

For more information, contact AHRQ Public Affairs (301) 427-1364: Karen Migdail, (301) 427-1855 (; HMS Public Affairs: John Lacy, (617) 432-0441 (

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