Integrating research on racial and ethnic disparities in health care over place and time.

Black Americans have substantially higher rates of cardiovascular mortality than other racial and ethnic groups in the United States, and they have experienced much less improvement in this important outcome than white Americans over the past 15 years. Racial disparities in cardiovascular treatment contributing to this mortality gap have been extensively documented. Numerous deficiencies, however, limit the usefulness of prior studies of racial and ethnic disparities in health care to guide policy and improve clinical practice and outcomes. Even studies with national scope have rarely assessed the extent to which variations among regions, local health markets, or hospitals might mediate observed racial disparities in care. Cross-sectional studies provide little information on changes over time. Furthermore, many studies have focused solely on black and white patients, providing little understanding of treatments and outcomes for other major racial and ethnic groups, including Latinos, Asian Americans, Pacific Islanders, and American Indians. Three new studies in this issue of Medical Care consider racial and ethnic differences in cardiovascular care across providers, over time, and across multiple groups. Each study contributes to our understanding of specific aspects of disparities in care. Using data from the Cooperative Cardiovascular Project (CCP) for nearly 140,000 elderly Medicare beneficiaries treated in the mid-1990s at approximately 4700 hospitals, Barnato and colleagues analyzed the relative contributions of within-hospital and between-hospital effects to disparities between black and white patients in medical therapies, coronary procedures, and risk-adjusted mortality after myocardial infarction. They concluded that black patients more often were treated in hospitals where effective medical therapies were less often prescribed, coronary procedures were more often used, and 30-day mortality rates were worse; thus, hospital assignment was an important mediator of disparities. These findings complement another recent study by Rathore et al from the CCP that attributed similar racial differences to regional variations in care, with black patients disproportionately treated in the Southeast where beta blockers are less often prescribed, coronary angioplasty is more common, and risk-adjusted mortality rates are higher than in the Northeast. These 2 studies both may be correct in attributing a part of racial disparities to variations in quality across hospitals or regions, respectively, but because each study assessed only 1 of these factors, the relative importance of hospital and regional effects cannot be determined. Furthermore, only very limited data were available