Weitzman S, Cooper L, Chambless L, Rosamond W, Clegg L, Marcucci G, Romm F, White A.
Gender, racial and geographic differences in the performance of cardiac diagnostic and therapeutic procedures for hospitalized acute myocardial infarction in four states.
Am J Cardiol 1997;79(6):722-6.

This study assessed whether procedure rates for coronary angiography, percutaneous transluminal coronary angioplasty (PCTA), coronary artery bypass grafting (CABG), and intravenous thrombolysis differed between blacks and whites and men and women. Data were derived from the Atherosclerosis Risk in Communities (ARIC) Study, which collected data on patients discharged from ARIC community hospitals for acute myocardial infarction (and a sample of other diagnoses). The communities included Forsyth County, North Carolina; the city of Jackson, Mississippi; and 8 suburbs of Minneapolis, Minnesota; and Washington County, Maryland. Since only Forsyth and Jackson had biracial populations, the racial comparisons were limited to these two communities. Patient between 35 and 74 years of age admitted to specified hospitals between 1987 and 1991 were included in the analysis. Repeat admissions and transfers were omitted following a standardized procedure.

During the study period, 66.6% of the hospitalized myocardial infarctions occurred in men and 14.9% in blacks. There were a number of sex and race differences in clinical characteristics: cardiogenic shock was more frequent in whites than blacks; congestive heart failure, diabetes, and hypertension were more frequent in blacks than whites; the percent of episodes of ventricular fibrillation was higher in blacks than whites; and congestive heart failure and diabetes were more frequent in women. The four diagnostic and therapeutic procedures also varied by sex, race, and area.

Overall women had lower rates of coronary angiography than men (p<0.01). (Race comparison for coronary angiography was not presented.) The rates of percutaneous transluminal coronary angioplasty were similar for men and women, with slightly higher rates for men in Jackson and lower for black men in Forsyth. Blacks had significantly lower rates of percutaneous transluminal coronary angioplasty than whites in the two biracial communities (p<0.01). CABG rates were lower in women than men (p<0.01) and blacks compared with whites (p<0.01). Intravenous thrombolytic therapy was given significantly less to blacks than to whites (p<0.01). (Gender comparison for intravenous thrombolytic therapy was not presented.)

Since some of the variation by area was due to the fact that facilities for the diagnostic and therapeutic procedures were not available in all hospitals, analyses were repeated only for hospitals with these facilities. Adjusting for severity of myocardial infarction and presence of comorbid conditions, the odds of having these procedures was higher for younger patients (35-54 years versus 65-74 years). The OR’s ranged from 2.0 to 3.5 for angiography, PTCA and thrombolytic therapy. The odds for CABG were not statistically significant for either teaching or non-teaching hospitals (OR=1.3, 95% confidence interval=0.08 to 2.1 for teaching hospitals and OR=1.4, 95% confidence interval=0.9 to 2.1 for non-teaching hospitals). The odds of coronary angiography, CABG, and thrombolytic therapy (but not PTCA) were lower for women than men (although this was only statistically significant for CABG in nonteaching hospitals OR=0.6, 95% confidence interval=0.4 to 0.8). The odds of all procedures were lower for blacks than whites.

OR’s ranged from 0.3 to 0.5 for PTCA, CABG and thrombolytic therapy. The OR’s were not statistically significant for coronary angiography (OR=0.6, 95% confidence interval=0.4 to 1.0 for teaching hospitals and 0.7, 95% confidence interval=0.5 to 1.1 for non-teaching hospitals). Again, the use of these procedures varied by race, sex, and area.

The authors consider possible explanations for the race and gender variations. They rule out selective admissions to hospitals that differ in their medical care or in their admission policies, as they controlled for severity of myocardial infarction and comorbidity and their results for teaching and non-teaching hospitals were similar. They also rule out the possibility that racial differences were due to differences in health insurance status of blacks compared with whites, since a previous study found similar patterns in a VA population where financial incentives were absent. They could not rule out the possibility that racial differences were due to physician supply or the appropriateness of these procedures for individual patients. (“In our study, it may be that a larger percent of these procedures is unjustified in whites than in blacks, and in men than in women.”) The authors also note that only a relatively small percentage of patients—both blacks and whites--received thrombolytic therapy, possibly because this type of treatment was not yet widely applied.