We found that racial differences in crude rates of aspirin and cardiac procedure use in Medicare patients hospitalized with myocardial infarction varied by region, whereas differences in beta-blocker prescription were comparable across all regions. Although some of these differences were attenuated after multivariable adjustment, regional variations in racial differences persisted for aspirin used on admission, use of any coronary revascularization, and coronary artery bypass graft surgery. These interactions reflected a general pattern of smaller or no racial differences in the Northeast and, in some cases, larger racial differences in the South. These differences, moreover, persisted after accounting for differences in physician or hospital characteristics, suggesting that racial differences in treatment typically assessed at the national level may possibly mask important region-specific practice patterns.
Our findings are similar to those of previous studies that used administrative data (10
). Racial differences in the use of coronary artery bypass graft surgery, although observed nationwide, were more than twice as large in the seven contiguous states of Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, and South Carolina as compared with any other region in an evaluation of 1986 Medicare data (11
). Similarly, racial differences in the use of cardiac catheterization, percutaneous coronary intervention, and coronary artery bypass graft surgery were greatest in the South within the Veterans Affairs health care system (12
) and later Medicare cohorts (10
). Larger racial differences in treatment in the South have also been observed for noncardiac services (10
). Use of the CCP database provides a methodological advancement over previous studies through the use of detailed clinical data. Moreover, our evaluation of four medical treatments in ideal cohorts permitted characterization of treatment differences as shortfalls in appropriate clinical care. Although our analysis was limited to selected therapies and procedures, our data suggest that, in at least some instances, racial variations in treatment vary by region. These results and those of prior investigators (10
) suggest that national evaluations of racial patterns of care offer an artificial representation of practices that may instead reflect region-specific phenomena.
The presence of smaller or no racial differences in the Northeast may offer important insights into the causes of and remedies for racial variations in treatment. As previous studies have reported, patients hospitalized for myocardial infarction in the Northeast— in particular, New England— have generally higher rates of aspirin and beta-blocker use. If these rates reflect a specific regional culture of evidence-based practice (24
), then such an orientation may explain why black patients received similar quality of care as did white patients. Similarly, smaller racial differences in cardiovascular procedure use may be a manifestation of the historically lower rates of cardiovascular procedure use in the Northeast (25
). If physicians in the Northeast are more selective in their use of coronary interventions, this may result in their being more likely to avoid overuse of cardiac procedures in white patients. Alternatively, smaller racial differences in the Northeast may reflect ‘structural’ characteristics of the region that were unmeasured in our analysis, such as easier access to hospitals.
Greater differences in treatment in the South may be attributable to factors other than race. One study demonstrated that black patients hospitalized with myocardial infarction in the South reported different symptoms than patients in other regions, suggesting that there may be region-specific cultural differences in patients’ perceptions of symptoms (26
). Such racial differences in symptom reporting, if greater in the South, may explain the larger racial differences in some of the treatments assessed. Lower rates of arteriographic evidence of coronary artery disease (27
) and myocardial infarction among black patients presenting with chest pain (28
) may decrease physicians’ suspicions of recurrent cardiac ischemia among black patients postdischarge and thus decrease the use of cardiac procedures. This phenomenon may be more pronounced in the South because of its larger population of black patients.
Distinctive regional characteristics of the South may also explain the larger racial differences in treatment. According to the 2000 U.S. Census, black patients in the South continue to cluster in counties where they comprise near majorities of the population (30
). Residence in these areas may exert an ‘environmental’ influence on treatment patterns not accounted for in our evaluation of racial confounding by hospitals. Black patients in the South reside predominantly in rural areas, and minorities in rural areas have historically poorer quality health care than rural white patients or minorities in urban areas (31
), although our analysis accounted for treatment in a rural hospital. Racial differences in distrust of the health care system are also higher in the South (32
), although it is unclear how issues of trust would influence the use of aspirin and beta-blockers. Racial differences in access to a usual source of care are greatest in the South as well, with black patients reporting higher rates of no usual source of care compared with black patients in the rest of the country (33
). Alternatively, if racial differences in acute myocardial infarction therapy reflect provider bias, then the larger racial disparities in care observed in the South may be an artifact of historically segregated health care (8
) or the greater prevalence of prejudicial attitudes toward minority groups in the region (34
This study has several limitations. First, we used census regions and did not explore variations in treatment in smaller geographic units. Our purpose, however, was not to assess small area variations, but rather to assess whether regional differences in practice patterns may modify racial differences in treatment. There is undoubtedly variation in racial differences in treatment within each of the census regions, but the general absence or smaller size of differences in the Northeast, and larger differences in the use of some treatments in the South, suggest that there are meaningful regional variations that merit further examination. Second, we based our analysis on Medicare fee-for-service beneficiaries hospitalized between 1994 and 1996, and thus our findings may not be generalizable to patients younger than 65 years or those enrolled in Medicare managed care plans, or may not reflect contemporary practice patterns. Third, we did not have access to patient-level socioeconomic data and thus cannot preclude the possibility that racial differences may represent effects attributable to income, education, occupation, or other social status measures. Fourth, we lacked data on supplemental Medicare insurance and thus cannot preclude the possibility that racial differences in treatment reflect variations in insurance, although such differences would also have to vary by region to modify the regional variations in racial differences observed in our study. Finally, because the CCP database does not contain coronary angiography data, we were not able to assess the appropriateness of revascularization based on coronary anatomy. Thus, differences in coronary revascularization use may reflect overtreatment of white patients, under-treatment of black patients, appropriate treatment, or some combination of these processes.
In conclusion, racial differences in crude rates of aspirin and cardiac procedure use among Medicare beneficiaries hospitalized with myocardial infarction varied by U.S. Census region. Although some regional variations in disparate treatment reflected confounding by regional differences in patient and provider characteristics, a general pattern of smaller differences in the Northeast and larger differences in the South were observed for some therapies. These patterns suggest that racial differences in treatment may reflect, in part, region-specific phenomena. Although this hypothesis merits further exploration, our findings indicate that national evaluations of racial differences in treatment may obscure meaningful geographic variations in racially disparate treatment, and thus support the adoption of region-specific analyses.