Diabetes status and racial differences in post-myocardial infarction mortality

Prior studies regarding the effect of racial status on post-myocardial infarction (MI) in subjects with diabetes have yielded conflicting results. We evaluated the effect of diabetes status on racial differences in post-MI mortality and morbidity for a 7-year period, from 1990 through 1997.

All patients discharged with the primary diagnosis of acute MI from any Veterans Affairs Medical Center in the country between October 1990 and September 1997 were identified. Demographic, comorbid conditions, inpatient, outpatient, mortality, and readmission data were extracted. Mortality, revascularization, readmissions, and length of hospital stay for MI were compared for the group with diabetes and that without diabetes. Comparison was made between black and white patients. Independent predictors of survival using a Cox regression model were examined.

We identified 67,889 patients with MI of whom 17,756 (26%) had diabetes. Race status was known for 66,506 subjects of whom 55,731 (84%) were white and 8437 (13%) were black. Regardless of the race, the diabetic patients tended to have higher mortality than nondiabetic patients. The post-MI mortality during the entire follow-up period tended to be similar between blacks and whites for the nondiabetic patients, whereas the mortality tended to be lower in blacks than in whites in diabetic patients.

Mortality from post-MI is significantly lower in blacks with diabetes than in whites with diabetes. In contrast, no racial difference in long-term mortality was seen among subjects without diabetes. Thus, it appears that diabetes status determines racial variation in post-MI mortality. The reasons for better survival post-MI of blacks in general and among subjects with diabetes in particular need to be further investigated.