Risk calculator redux: More evidence suggests recalibrations required

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Another study found the risk prediction tool from the American College of Cardiology (ACC) and the American Heart Association (AHA) and three other Framingham-based calculators significantly overestimate cardiovascular risk.

Researchers put five tools to the test of estimating 10-year cardiovascular risk among the MESA (Multi-Ethnic Study of Atherosclerosis) population: the ACC-AHA Atherosclerotic Cardiovascular Disease (ASCVD) Risk Score, Framingham Risk Score (FRS) – Coronary Heart Disease (CHD), FRS- Cardiovascular Disease (CVD), Adult Treatment Panel III (ATPIII-FRS-CHD) and Reynolds Risk Score (RRS).

The ACC-AHA-ASCVD risk calculator was the most recently released of the five tools. It was issued with guidelines in 2013 and has been the center of some controversy since.

The four Framingham-based risk tools overestimated risk in men by 37 to 154 percent and in women by 8 to 67 percent. The overestimation using the ACC-AHA-ASCVD tool was 86 percent in men and 67 percent in women; the total dissonance of using the ACC-AHA-ASCVD tool was 78 percent.

The tool that most closely estimated risk to the actual findings of MESA was RRS. RRS underestimated a total of 3 percent; for men, it overestimated by 9 percent and for women, it underestimated by 21 percent.

This places some patients in a gray zone. If their risk of cardiovascular disease is low, treating them as though they had a higher risk could mean additional, unnecessary expenses and side-effect risks.

“Accurate estimation of absolute risk underpins the effort by the AHA and ACC to update the prevention guidelines and is required to effectively balance therapeutic risk and benefit of an intervention for an individual patient or entire population,” wrote Andrew P. DeFilippis, MD, MSc, of the University of Louisville in Kentucky, and colleagues. Part of the underlying problem, they added, was that these risk models did not take into account changed relevance of risk factors in modern cohorts.

“Physicians treating patients similar to those in MESA may consider interpreting the absolute risk generated by the new risk score with caution,” wrote DeFilippis et al.

Paul M Ridker, MD, MPH, and Nancy R. Cook, ScD, both of Brigham & Women's Hospital in Boston, emphasized the importance of recalibrating risk tools in an accompanying editorial. However, “Clinicians might recalibrate the algorithm so that it tracks more closely with contemporary evidence, simultaneously calculate multiple risk algorithms as currently done in some Mayo Clinic prevention programs, or elect to ignore the problem and accept that more persons will be treated with a class of drugs proven to reduce vascular event rates,” they wrote.

The study was published Feb. 16 in the Annals of Internal Medicine.