Prognostic value of the Duke Treadmill Score in diabetic patients

Background The Duke Treadmill Score (DTS) is an established clinical tool for risk stratification of coronary artery disease. We sought to assess the prognostic value of the DTS in diabetics compared with nondiabetics in this study. Methods We studied 100 diabetics and 202 age- and sex-matched nondiabetic controls without known coronary artery disease risk stratified by DTS and followed for a median duration of 6.6 years. The association between DTS and primary, secondary outcomes, composite events, and rate of coronary angiography was tested. Results Survival free from cardiac death, nonfatal myocardial infarction, congestive heart failure, or early and late revascularization was 89%, 54%, and 13%, respectively, in the low-, intermediate-, and high-risk categories of diabetic group (P < .0001), and 91%, 57%, and 17%, respectively, in the low- to high-risk groups of nondiabetics (P < .0001). During follow-up, diabetics had more secondary events (P = .011) and coronary angiography (P < .001) compared with nondiabetics. The DTS was a strong independent predictor of composite events in both diabetics (P < .001) and nondiabetics (P < .001). A significant number of diabetics were classified as intermediate risk and had a significantly higher incidence of coronary angiography (87.5% vs 70.8%, P = .032) and late revascularizations (35.4% vs 15.3%, P = .011) within this risk group compared with nondiabetics. Survival free from major adverse cardiac events differed significantly across the 3 Duke risk groups for diabetics (P = .002) but not for controls (P = .07). Survival free from composite events differed significantly across the 3 Duke risk groups for both diabetics and nondiabetics (P < .0001). Overall, diabetics had higher rates of major adverse cardiac events, composite events (P = .011), and coronary angiography (P < .001) than nondiabetics. The DTS is a strong predictor of survival free of composite events in both groups by multivariate analysis (P < .005). Conclusions The DTS predicted survival free from MACE and composite events equally well in patients with and without diabetes.