Nontraditional risk factors like coronary artery calcium (CAC), ankle-brachial index (ABI), and family history may help predict atherosclerotic cardiovascular disease (ASCVD) events, according to research recently published in the Journal of the American College of Cardiology.

The American College of Cardiology and American Heart Association (ACC/AHA) updated their cholesterol guidelines in 2013, which included updated ASCVD risk estimates that improved discrimination with added nontraditional cardiovascular risk factors. However, the ACC/AHA guidelines did not provide evidence concerning the benefits of the additional risk factors on ASCVD risk assessment.

Researchers conducted the study to analyze the accuracy and improvement in ASCVD risk reclassification when CAC, ABI, family history, and high-sensitivity C-reactive protein (hsCRP) levels are added to the pooled cohort equation (PCE).


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Cox proportional hazards survival model, Harrell’s C statistics, and net reclassification improvement (NRI) were used to analyze the new PCE.

Of the 5185 patients analyzed in the study, 9.8% had diabetes and 13.6% were current smokers. The mean age was 61 years and 53.1% were women. After a 10-year follow-up period, the researchers recorded 320 (6.2%) ASCVD events, including myocardial infarction (43.4%), fatal or nonfatal strikes (41.3%), and CHD-related death (15.3%)

The CAC score improved the Harrell’s C statistic (0.74 vs 0.76, P=.04), while ABI, hsCRP levels, and family history showed no improvement when added to the PCE.

The event NRI when CAC scores were added was 0.178 (95% confidence interval [CI]: 0.080-0.256) compared with the nonevent NRI of -0.059 (95% CI: -0.075 to -0.030). ABI had the highest nonevent NRI (0.004; 95% CI: -0.004 to 0.011), but showed significant improvement (event NRI 0.013; 95% CI: -0.034 to 0.051).

“The addition of the CAC score resulted in a larger improvement in the classification of risk than the other additional risk markers but was limited to an improvement in classification of events,” the authors noted.

CAC score, ABI, and family history were independently associated with incident ASCVD, but these factors resulted in varying improvement in reclassification. Further research should be conducted to verify the results in other patient cohorts.

Reference

Yeboah J, Young R, McClelland R, et al. Utility of Nontraditional Risk Markers in Atherosclerotic Cardiovascular Disease Risk Assessment. J Am Coll Cardiol. 2016; 67(2):139-147. doi:10.1016/j.jacc.2015.10.058.