Purpose: Diabetes is a recognized risk factor for the development of cardiac disease, but its importance as a prognostic factor among patients with known cardiovascular disease is less clear. We evaluated survival in patients with and without diabetes who underwent cardiac catheterization for presumed coronary artery disease.
Subjects and methods: We analyzed data from a prospective cohort study that captures detailed clinical information and longitudinal outcomes for all patients who undergo cardiac catheterization in Alberta, Canada. We studied 11,468 patients, 1959 (17%) of whom had diabetes. Logistic regression was used to model predictors of 1-year mortality, and proportional hazards analysis was used to model predictors of survival up to 3 years after cardiac catheterization.
Results: One-year mortality was 7.6% for patients with diabetes versus 4.1% for those without diabetes (odds ratio = 1.9, 95% confidence interval [CI]: 1.6 to 2.3). After adjusting for other characteristics of the patients, including comorbid conditions, previous cardiac history, coronary anatomy, and renal function, the odds ratio for 1-year mortality was 1.1 (95% CI: 0.8 to 1.3). Similarly, the adjusted hazard ratio for longer term mortality was 1. 2 (95% CI: 1.0 to 1.4, mean follow-up of 702 days).
Conclusions: These results suggest that there is little or no independent association between diabetes and mortality for up to 3 years after cardiac catheterization. Estimates of short- to intermediate-term prognosis for diabetic patients with coronary artery disease should be based on the presence of other prognostic factors associated with diabetes.