This study utilized data from the National Hospital Discharge Survey for the years 1988-1990 to compare rates of cardiac catheterization, percutaneous transluminal coronary angioplasty (PCTA) and coronary-artery bypass surgery (CABG) by race and sex. Those selected for the present analysis from this nationally representative sample of hospital discharges were people at least 35 years of age assigned a diagnosis of acute myocardial infarction.

Age was inversely related to the use of catheterization and PTCA. After adjusting for age, the rates of cardiac catheterization, PTCA, and CABG differed substantially by race and sex. The rates were generally highest for white men, followed by white women, then black men, and were lowest for black women.

The authors stratified the analysis by insurance type (in addition to adjusting for age) in order to examine whether insurance coverage explained part of the race and sex patterns. For cardiac catheterization, there were no race differences among patients with private or Blue Cross health insurance; however, there were differences among patients with Medicare, Medicaid, or no insurance. Thus, insurance coverage may explain some of the variation in catheterization rates by race. Also, the rates for all the procedures for every race/sex group were lowest for those with Medicaid or no insurance, again indicating that health insurance might be responsible for race and gender patterns in access to cardiac procedures.

After adjusting for age, type of health insurance, hospital size and type, region, hospital transfer (yes or no), and in-hospital mortality rate, the odds ratios (OR) for black versus white men undergoing these cardiac procedures were 0.61 (95% confidence interval = 0.41 to 0.91) for catheterization, 0.31 (0.21 to 0.58) for PCTA, and 0.50 (0.44 to 0.50) for CABG. The OR’s for black women versus white men were 0.48 (0.27-0.87) for catheterization, 0.45 (0.19 to 1.03) for PCTA, and 0.26 (0.11 to 0.61) for CABG. The OR’s for white women versus white men were 0.78 (0.67 to 0.92) for catheterization, 0.94 (0.72 to 1.24) for PCTA, and 0.54 (0.41 to 0.70) for CABG. These findings held when the authors matched for hospital of admission and then adjusted for the other factors. Thus, even when patients were admitted to the same hospital, blacks and women were less likely than white men to undergo cardiac procedures.

Since it has been suggested that rates of procedures may vary by race and sex due to access to cardiologists, the authors reassessed only those patients who had undergone cardiac catheterization with regard to the subsequent use of PTCA and CABG. The rates of PTCA did not differ significantly by race and sex, but both black and white women had significantly lower odds of CABG than white men. Although not statistically significant, the overall race and sex patterns remained evident.

In their discussion, the authors consider two possible explanations for these race and sex patterns in use of cardiac procedures that were not specifically tested in this analysis: physician bias and patient preferences. The authors cite the findings from the CASS study (Maynard et al 1986), stating “(the observed racial patterns) suggest that physicians were more aggressive in their therapeutic approach toward white patients” and “(the observed racial patterns) could arise from differing attitudes about risk or confidence in the medical system, or it could relate to factors such as differences in supplemental insurance and income that influence a patient’s ability to afford expensive procedures.” The authors also note that they “could not determine the extent to which these differences represent bias based on race and sex versus the degree to which race and sex reflect other cultural and socioeconomic factors that affect physician and patient behavior.” They do conclude, however, that “the data from this and other studies suggest that rates of invasive cardiac procedures are greatly influenced by the race and sex of the patient.”