Predicting future cardiovascular disease: do we need the oral glucose tolerance test?

OBJECTIVE: Our objective was to compare the performance of oral glucose tolerance tests (OGTTs) and multivariate models incorporating commonly available clinical variables in their ability to predict future cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS: We randomly selected 2,662 Mexican-Americans and 1,595 non-Hispanic whites, 25-64 years of age, who were free of both CVD and known diabetes at baseline from several San Antonio census tracts. Medical history, cigarette smoking history, BMI, blood pressure, fasting and 2-h plasma glucose and serum insulin levels, triglyceride level, and fasting serum total, LDL, and HDL cholesterol levels were obtained at baseline. CVD developed in 88 Mexican-Americans and 71 non-Hispanic whites after 7-8 years of follow-up. Stepwise multiple logistic regression models were developed to predict incident CVD. The areas under receiver operator characteristic (ROC) curves were used to assess the predictive power of these models.
RESULTS: The area under the 2-h glucose ROC curve was modestly but not significantly greater than under the fasting glucose curve, but both were relatively weak predictors of CVD. The areas under the ROC curves for the multivariate models incorporating readily available clinical variables other than 2-h glucose were substantially and significantly greater than under the glucose ROC curves. Addition of 2-h glucose to these models did not improve their predicting power.
CONCLUSIONS: Better identification of individuals at high risk for CVD can be achieved with simple predicting models than with OGTTs, and the addition of the latter adds little if anything to the predictive power of the model.