The importance of glycosylated hemoglobin A1c (A1c) control as part of comprehensive risk factor management in patients with stable ischemic heart disease (SIHD) and diabetes mellitus (DM) is controversial.
The purpose of this study was to determine whether a greater number of controlled risk factors at 1 year, including A1c, affects survival in patients with DM and SIHD.
Of 690 patients with DM followed in the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial, 592 (86%) had complete ascertainment of 7 pre-specified risk factors at baseline and after 1 year: systolic blood pressure, low-density lipoprotein cholesterol, nonsmoking, physical activity, diet adherence, body mass index, and A1c. The primary outcome measure was mortality beyond 1 year after randomization.
During a mean follow-up of 7.0 ± 4.2 years beyond 1 year after randomization, 186 subjects died (31.4% overall, 4.5%/year). The greater the number of risk factors controlled at 1 year, the higher the probability of survival (unadjusted log rank p = 0.002). Compared with 0 to 1 controlled risk factors, attaining 3 to 7 goals predicted progressively lower mortality (hazard ratio for control of 6 or 7 risk factors was 0.13; 95% confidence interval: 0.05 to 0.40). Importantly, only 10.3% of subjects achieved control of 6 or 7 risk factors. In multivariate analysis, the strongest predictors of improved survival were no smoking, regular physical activity, dietary adherence, and A1c <7%.
In this high-risk subset of SIHD patients with DM, the number of controlled risk factors, particularly lifestyle behaviors and A1c, were associated with improved survival. (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation; NCT00007657)