Stanford, CA—Because of improvements to risk calculation for cardiovascular disease, as many as 11 million Americans might need different prescriptions for statins, blood pressure medications, and aspirin, a new study points out.

The changes might especially affect African Americans, according to the article in Annals of Internal Medicine, because older risk calculations from 2013 might have underestimated their risks.

Pooled Cohort Equations (PCEs) were created in 2013 to aid physicians in evaluating patient risk factors and deciding whether to prescribe statins, aspirin, or blood pressure medications to prevent heart attack or stroke.

Since then, questions have been raised about whether PCEs might be putting patients at risk for over- or undertreatment.

Stanford University–led authors of the new study note that one of the main datasets used to derive the original equations had information from people who were 30 to 62 years old in 1948, and now—in all likelihood—would be dead. The old data also underrepresented African Americans.

For example, the study team, which created an updated set of calculations using modern cohorts and current methodologies, found that 2013 PCEs overestimated 10-year risk for atherosclerotic cardiovascular disease by an average of 20% across risk groups.

“We found that there are probably at least two major ways to improve the 2013 equations,” explained senior author Sanjay Basu, MD, PhD, assistant professor of primary care outcomes research at Stanford. “The first was well-known: that the data used to derive the equations could be updated.”

“A lot has changed in terms of diets, environments and medical treatment since the 1940s,” Basu added. “So, relying on our grandparents’ data to make our treatment choices is probably not the best idea.”

In general, the older risk calculator overestimated risk—but not always, he emphasized, pointing out, “So while many Americans were being recommended aggressive treatments that they may not have needed according to current guidelines, some Americans—particularly African-Americans—may have been given false reassurance and probably need to start treatment given our findings.”