New REGARDS data show heart attack, stroke risk equations are accurate despite initial criticisms

Since their release in November 2013, cholesterol treatment guidelines from the American Heart Association and the American College of Cardiology have drawn concern from the medical community. One of the issues raised was with risk equations to predict heart attack and stroke, but new findings from the University of Alabama at Birmingham published in the Journal of the American Medical Association support the accuracy of the equations.

A commentary published in The Lancet following the guidelines’ release suggested that the new formulas predicted that too many people would have a heart attack or stroke. According to the guidelines, it was recommended that doctors prescribe the cholesterol-lowering therapy statins to all patients who were considered high-risk by the AHA/ACC risk equations.

If the equations were overestimating risk, patients could be put on statins when they do not need to be treated, costing them money and exposure to potential side effects. Additionally, since they are not high-risk, they would not have an offsetting risk reduction of heart attack and stroke.

Using data from the Reasons for Geographic And Racial Differences in Stroke, or REGARDS, study, 10,997 people who were not taking statins, did not have a history of heart attack or stroke, and did not have diabetes, were studied to validate the formula. At baseline in 2003-2007, participants underwent a physical examination that allowed investigators to use the AHA/ACC formulas to estimate each person’s risk for having a heart attack in the next 10 years.

Participants in REGARDS have been followed for heart attacks and strokes. Using the data collected, researchers compared heart attack and stroke rates observed in the REGARDS study participants to those predicted by the formulas.

Participants in REGARDS have been followed for heart attacks and strokes. Using the data collected, researchers compared heart attack and stroke rates observed in the REGARDS study participants to those predicted by the formulas.

“The formulas worked very well — the rates of heart attack and stroke observed were very similar to those predicted by the formulas,” said Paul Muntner, Ph.D., professor in the UAB Department of Epidemiology and lead study author. “Additionally, participants who were predicted to have high risk were the ones most likely to have heart attacks and strokes, while those who were predicted to have a low risk had very low incidence of heart attacks or strokes.”   

Muntner says these findings demonstrate that the risk equations published by the AHA/ACC are accurate and can be used by physicians to determine whether their patients should start taking statins.   

“We think this is very important because there are millions of patients who may benefit from taking statins, and doctors need to identify these patients while not prescribing treatment for patients who may receive little benefit,” Muntner said.

Because the formulas were designed to help doctors identify which patients to treat and which patients may not benefit much from treatment, Muntner hopes their findings will provide physicians confidence that these equations can be used to provide valid information.

“We hope that showing that the formula works in a large nationwide group of adults will lead doctors to use it,” Muntner said. “In turn, this could lead to higher rates of appropriate use of statins and reduction in heart attack and stroke risk.”

While the REGARDS study is ongoing, Muntner says follow-up at the time of their analyses was limited to five years. They plan to perform additional analyses once longer follow-up of participants becomes available.