Characterizing Young Patients With Diabetes and Non–ST-Segment Elevation Acute Coronary Syndromes

RESEARCH DESIGN AND METHODS—

The details of the CRUSADE Initiative have been previously published (4–6). In brief, patients included in the CRUSADE Quality Improvement Initiative were admitted to 498 participating U.S. hospitals with ischemic symptoms at rest within 24 h before presentation and high-risk features including ST-segment depression, transient ST-segment elevation, and/or positive cardiac markers (elevated troponin I or T and/or creatine kinase-MB more than the upper limit of normal for participating institutions). For this study, we analyzed data from 9,643 patients aged ≤45 years out of a total of 138,719 NSTE ACS patients enrolled in the CRUSADE Quality Improvement Initiative between January 2001 and March 2005. Hospitals participating in the CRUSADE Quality Improvement Initiative anonymously collect detailed demographics, clinical and laboratory features, process of care, and in-hospital outcomes data through retrospective chart review. Patients were categorized into two groups: those with and without history of known diabetes as noted on the case-report forms.

Statistical analysis

Quality-of-care indicators for both acute care and discharge care were compared for patients with class IA or IB indication and without any contraindications to such treatments (7). Care patterns and in-hospital events were adjusted for a broad range of patient and hospital characteristics using multivariate logistic regression analysis.

RESULTS—

Among patients aged ≤45 years, 18.8% (n = 1,808) had diabetes. In contrast, 34% of patients aged >45 years had diabetes. Furthermore, younger patients with diabetes comprised 1.3% of overall and 4% of all patients with diabetes in the CRUSADE Quality Improvement Initiative. Young diabetic patients were slightly older and more likely to be female (Table 1). Obesity was more prevalent in diabetic patients, as were most comorbid conditions such as hypertension; dyslipidemia; prior myocardial infarction, revascularization, heart failure, or stroke; peripheral arterial disease; and renal insufficiency. Presenting heart rate and systolic blood pressure were higher and signs of heart failure less frequent in patients with diabetes. Serum triglyceride and LDL were higher in patients with diabetes. The use of all evidence-based therapies (adjusted for confounding factors) were similar in the two groups with the exception of discharge aspirin, clopidogrel, ACE inhibitor, dietary counseling, and referral for cardiac rehabilitation—all of which were significantly higher in patients with diabetes.

After adjusting for confounding, no differences were noted in the incidence of in-hospital mortality (1.4 vs. 1.0%, odds ratio [OR] 0.62 [95% CI 0.31–1.23]), death or re-infarction (3.4 vs. 2.6%, 0.90 [0.61–1.33]), heart failure (4.6 vs. 2.0%, 1.21 [0.86–1.70]), or shock (1.2 vs. 1.3%). However, patients with diabetes were more likely to receive a blood transfusion (9.4 vs. 4.7%, 1.35 [1.07–1.69]).

CONCLUSIONS—

Our data suggest that the presence of diabetes among young NSTE ACS patients is common. We have demonstrated (8) that diabetes was more prevalent among female patients and African Americans with NSTE ACS, and patients with diabetes more commonly had other comorbid medical conditions and high-risk features such as multivessel coronary disease. Most striking was the fact that ∼60% of young patients with diabetes were morbidly obese (BMI >30 kg/m²). Additionally, even among young NSTE ACS patients without diabetes, 40% were obese. Obesity is commonly recognized to be interrelated with glucose intolerance and insulin resistance, among other factors, as a component of metabolic syndrome (9).

We found no difference in the use of acute medications during hospitalization. More impressive was the somewhat better adherence to discharge medications and lifestyle modification strategies in younger patients with diabetes compared with those without diabetes. While overall revascularization rates were similar in the two groups, the choice of revascularization strategy was somewhat different; more patients with diabetes underwent coronary artery bypass surgery, and more nondiabetic patients were treated with percutaneous coronary interventions. This may have been a result of higher prevalence of multivessel coronary disease and more left ventricular systolic dysfunction among patients with diabetes, as well as better survival reported with bypass surgery compared with percutaneous coronary interventions among those with diabetes and multivessel disease (10).

Finally, in-hospital outcomes, particularly mortality, were not significantly different between the two groups. This is in contrast with previously published studies (11,12) (predominantly consisting of middle-aged or older patients) that found diabetes to be an important predictor of increased mortality and myocardial infarction among patients presenting with NSTE ACS. Only the risk of blood transfusion was increased by twofold among young patients with diabetes and remained significantly higher despite adjustments for confounding clinical variables. This increased risk of bleeding is somewhat counterintuitive, as diabetes has long been recognized as a prothrombotic state (9) and requires future investigations.

In conclusion, our findings indicate that, despite a higher prevalence of comorbid conditions among young NSTE ACS patients with diabetes compared with those without diabetes, adherence to guideline-based therapies and in-hospital mortality are similar among these two groups. Future studies are needed to address the influence of diabetes on long-term outcomes in young patients with NSTE ACS and to decrease the alarming rates of obesity among this population.