Temporal changes in the management and outcome of Canadian diabetic patients hospitalized for non-ST-elevation acute coronary syndromes

Background: There are limited data on the contemporary management and outcomes of non-ST-elevation acute coronary syndrome (NSTE-ACS) patients with diabetes in the "real world." We sought to evaluate (1) the temporal changes in the medical and invasive management and (2) in-hospital outcome of NSTE-ACS patients with and without diabetes.

Methods: We included Canadian patients hospitalized for NSTE-ACS enrolled in 4 consecutive, prospective, multicenter registries: Canadian ACS-I (n = 3259; 1999-2001), ACS-II (n = 1,956; 2002-2003), Global Registry of Acute Coronary Events (GRACE/GRACE2 [n = 7,561; 2004-2007]) and Canadian Registry of Acute Coronary Events (n = 1,326; 2008). Participants were stratified by the presence or absence of preexisting diabetes on admission. Temporal changes in patient management and outcomes were evaluated across the 4 registries. Multivariable analyses were performed to determine the independent prognostic significance of diabetes.

Results: Of the 14,102 NSTE-ACS patients, 4,046 (28.7%) had previously diagnosed diabetes. Patients with diabetes were older; were more likely to have prior cardiac history including myocardial infarction, revascularization, and heart failure; and had worse Killip class and higher GRACE risk score (all P < .001). Over time, there were significant increases in the use of in-hospital coronary angiography and revascularization. However, diabetic patients were less likely to undergo coronary angiography (52.5% vs 57%, P < .001) or revascularization (28.4% vs 33.4%, P < .001). The underuse of invasive procedures in diabetic patients was seen in all registries and was persistent over time. Overall, compared with the group without diabetes, diabetic patients had higher unadjusted rates of in-hospital mortality (3.0% vs 1.6%, P < .001). In multivariable analysis adjusting for components of the GRACE risk score, diabetes remained an independent predictor of in-hospital death (adjusted odds ratio 1.66, 95% CI 1.30-2.11, P < .001).

Conclusions: Over the last decade, NSTE-ACS patients with diabetes continue to be treated more conservatively, despite evidence that they would derive similar or even greater benefits from aggressive treatment. This underutilization of evidence-based therapies among diabetic patients with NSTE-ACS in the "real world" may partly explain their worse outcome.