A calculator used to predict heart disease risk for millions of Americans could be overestimating risk by 500%, according to a Kaiser Permanente study published today in Journal of the American College of Cardiology.
The calculator, released by the American Heart Association in 2013, evaluates a variety of factors, like blood pressure and smoking status, to determine patients’ risk of heart attack or stroke in the next 10 years. Those with a risk of 7.5% or more are advised to take a statin, and those with a risk of 5% or more are encouraged to consider taking a statin.
Using Epic data, Kaiser Permanente conducted a five-year study of 307,591 patients that compared their predicted risk, according to the calculator, to the actual incidence of heart attack and stroke. At the end of the five years, there had been 2,061 such events—compared to the calculator’s prediction of 10,151. Further analysis showed that the risk of heart attack or stroke, as predicted by the calculator, was as much as five to six times higher than the observed incidence.
If physicians use the calculator to identify patients who should be taking statins, as the American College of Cardiology recommends, they could be prescribing statins based on an inflated estimated risk—leading many Americans to take statins unnecessarily.
While the reason for the overestimation is unclear, study authors and other researchers say the calculator is based on data from the 1990s, when treatments were less advanced and studies targeted patient populations that were older and white. In contrast, authors of Kaiser’s study say it’s more ethnically diverse and more representative of the broader population.
Kaiser’s findings are similar to those from previous studies, but Kaiser’s study is much larger in scale and excludes patients taking statins to avoid skewing results.
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