When combined with conventional risk factors, hemoglobin A1c modestly aids in prediction of atherosclerotic cardiovascular disease risk, according to a retrospective analysis published online Sept. 8 in Circulation: Cardiovascular Quality and Outcomes.
Conventional risk factors for CVD such as sex, age, blood pressure, smoking, or lipid level are important tools used to aid in clinical decision making. However, there is current debate about whether to include hemoglobin A1c in the algorithms, despite the clear association of CVD with glucose levels, said Jamie A. Jarmul of the University of North Carolina in Chapel Hill, and colleagues.
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They used data from the 2011-2012 National Health and Nutrition Examination Survey (NHANES) to analyze CVD risk factors and HbA1c in 2,000 individuals aged 40-79 years without a history of diabetes or CVD. Utilizing a regression model, the distribution of HbA1c based on patient characteristics was predicted. The impact of the predicted HbA1c on the 10-year atherosclerotic CVD risk was calculated with the use of example clinical scenarios.
Factors considered significant predictors of HbA1c were HDL-cholesterol, total cholesterol, current smoking, sex, age, race/ethnicity, and systolic blood pressure. Further, individuals who were of black, Asian, or Hispanic race/ethnicity were associated with prediction of higher HbA1c.
The investigators noted that by using the final model, they found a modest effect of HbA1c on post-test atherosclerotic CVD risk in participants with intermediate risk. In the example clinical scenarios, an HbA1c of more than 6.5% was associated with increase in posttest atherosclerotic CVD risk by 1.0%-2.5% points. An HbA1c less than 5.7% was associated with a lowering of posttest atherosclerotic CVD risk by 0.4%-2.0% points (Circ Cardiovasc Qual Outcomes. 2015 Sep 8. doi:10.1161/CIRCOUTCOMES.115.001639). The authors note the posttest atherosclerotic CVD risk of having an elevated HbA1c (greater than 6.5%) is similar to being 5 years older.
“The results we have presented here represent a necessary intermediate step before conducting these more comprehensive analyses assessing the utility of HbA1c testing in ASCVD [atherosclerotic cardiovascular disease] primary prevention and the larger question of universal screening for abnormal blood glucose levels,” the authors noted.
The National Institutes of Health supported the study. Dr. Pignone reports being a member of the U.S. Preventive Services Task Force (USPSTF).