Young RF, Waller JB Jr, Kahana E.
Racial and socioeconomic aspects of myocardial infarction recovery: studying confounds.
Am J Prev Med 1991;7(6):438-44.

The purpose of this study was to simultaneously assess both race and socioeconomic status effects on survival after myocardial infarction (MI). The study sample was recruited from the coronary care registries of seven hospitals in a large urban area of the United States (data collection period not reported). Participants were followed at six-weeks and one year after being discharged. Of 246 patients initially recruited, 166 were re-interviewed at the one year point, and data on 36 patients who had died were also collected at the one year point.

At the one year follow-up point, black patients had greater impairment of physical functioning and more cardiac symptoms than white patients. Blacks were more likely to experience cardiac morbidity than whites (although the differences did not reach statistical significance) and blacks were 20% more likely to die by the one year point (95% confidence interval, 0.66 to 2.32). With regard to service utilization, black patients had less chance of receiving both state of the art and standard preventive health services than white patients (including cardiac rehabilitation programs, scheduling for diagnostic coronary catheterization, having a cardiologist, being enrolled in patient education programs, and receiving smoking and exercise information).

At the one-year follow-up point, low SES patients (measured by education) also had poorer physical health and more cardiac symptoms. Low SES patients, again, were more likely to experience cardiac morbidity than whites, but there was no difference in morbidity. Finally, low SES patients were less likely to receive coronary catheterization, coronary artery bypass surgery, care by a cardiologist, and cardiac risk reduction advice.

In order to assess interaction effects, the authors estimated the rank of each of the four race-SES categories with regard to health status measures, secondary prevention measures, tertiary prevention measures, and overall average rank. White high SES patients ranked best in each category. In the health status category, high SES was more important than white race in ranking. In secondary prevention, white race was more important than high SES in ranking. In tertiary prevention, the black low SES category unexpectedly achieved a higher rank than either white low SES or black high SES. Finally, the overall average rank was white high SES, white low SES, black high SES, and black low SES.

The authors also conducted a multiple regression analysis that included an interaction term for race-SES and found that this term was statistically significant for physical functioning (black-low SES patients did worse) and for cardiac change (white-high SES patients improved most).

The authors conclude that this study demonstrates serious racial and socioeconomic gaps that involve mortality, morbidity and preventive health care. Furthermore, the post-MI outcomes were significantly predicted by the joint effects of race-SES variables. "The abundant white/black comparisons that appear in the literature could be more enlightening if they controlled for variables such as SES that represent heterogeneity with racial groups. We should not be concluding that the black health gap is due to poverty...Neither can we attribute the differences to genetics..."

The authors suggest possible explanations that include demographic patterns, structural variables (including the availability of medial services and provision of adequate care), and the health beliefs and practices of individuals. Finally, they add that, "these data suggest that if physician management practice were to be altered, less educated black health patients might share in some of the survival gains that the population at large is enjoying."