Franks AL, May DS, Wenger NK, Blount SB, Eaker ED.
Racial differences in the use of invasive coronary procedures after acute myocardial infarction in Medicare beneficiaries.
Ethn Dis 1993;3(3):213-20.

It has been suggested by other studies that the racial disparities observed in cardiac care could be related to an “unequal access to hospitals equipped to provide invasive coronary procedures, different survival patterns, or different temporal delays in use of invasive procedures.” To address these issues, this study used Medicare enrollment and hospital claims data for the calendar year 1988 to examine racial differences in the use diagnostic procedures (arteriography, cardiac catheterization) and therapeutic procedures (coronary artery bypass grafting (CABG), coronary artery angioplasty (PTCA)) for patients aged 65 years or older hospitalized with acute myocardial infarction. The question of access was addressed by identifying patients in the study population with a first-listed CHD diagnosis in a “providing” hospital (“provision” of coronary procedures was determined based on billing information) and labeling these patients as having “access.”

The findings regarding the differences in cardiac care for black versus white patients supported previous studies. After controlling for possible confounding variables, including Medicaid eligibility as a crude measure of poverty, access to hospitals providing invasive coronary procedures, and adequate survival after AMI to allow for a procedure, the odds ratios for whites versus blacks were as follows: white men were 2.0 times more likely (95% CI: 1.8-2.1) to receive diagnostic procedures than black men and 1.8 times more likely (95% CI: 1.6-2.0) to undergo therapeutic procedures. Interestingly, the authors reported only a small difference between blacks and whites with respect to access to hospitals performing invasive coronary procedures (63.6% of white men versus 62.4% of black men had access to these hospitals).

The investigators conducted additional analyses of the data to examine several possible explanations for the differences observed. They characterized hospitals according to the degree of coronary procedures performed and the racial composition of the population and found that these factors “did not materially alter the racial differences described.” The authors also examined the “possibility that black patients may be more likely to have a medical history with contraindications for invasive coronary procedures or may be more likely to have undergone these procedures in the past.” The “racial differences persisted virtually unchanged after adjustment for these prior diagnoses and procedures.” The authors conclude that the “discrepancies could not be attributed to differences in age, comorbid conditions, geographic region, duration of survival after AMI, poverty status as measured by Medicaid eligibility, or access to hospitals that provide invasive cardiac procedures.”

A possible limitation of this study is that no data were available on supplemental insurance; whites may have more access to supplemental insurance and therefore may be more likely to afford the residual cost of procedures that are not covered by Medicare.