Glycosylated Hemoglobin A1c as a Marker Predicting the Severity of Coronary Artery Disease and Early Outcome in Patients With Stable Angina

Study Questions:

Does glycosylated hemoglobin A1C (HbA1c) predict the severity and clinical outcomes in patients with stable coronary artery disease (CAD)?

Methods:

A total of 1,433 patients with stable angina who underwent coronary angiography were followed up for an average of 12 months. The patients were classified into three groups by tertiles of baseline HbA1c level (low group <5.7%, n = 483; intermediate group 5.7-6.3%, n = 512; high group >6.3%, n = 438). The relationships between the plasma HbA1c and severity of CAD and early clinical outcomes were evaluated.

Results:

Mean age was 58 years. Those in the high group were older, had more hypertension, diabetes (43.8% vs. 18% in the other two groups), hyperlipidemia, three-vessel CAD, higher C-reactive protein, and more likely on evidence-based CAD treatment. Area under the receiver operating characteristic curve (AUC = 0.67, 95% confidence interval [CI], 0.63-0.71; p < 0.001) and multivariate logistic regression analysis suggested that HbA1C was an independent predictor of severity of CAD (odds ratio, 1.60; 95% CI, 1.29-1.99; p < 0.001) after adjustment. During follow-up, 133 patients underwent prespecified outcomes. After adjusting for multiple variables in the Cox regression model, HbA1C remained an independent predictor of poor prognosis (hazard ratio, 1.28; 95% CI, 1.12-1.45; p < 0.001).

Conclusions:

The authors concluded that a high level of baseline HbA1c appears to be an independent predictor for the severity of CAD and poor outcome in patients with stable CAD.

Perspective:

Diabetic men and women with CAD have a worse outcome than nondiabetics. Similarly, as this study subgroup analysis indicated, the predictive power of plasma HbA1c was only found in patients with stable angina who had a history of diabetes (p < 0.001). However, the findings support clinical trials designed to test whether drugs that affect glycemic control or insulin sensitivity can improve the outcome in nondiabetics with stable CAD.


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