Two studies released Tuesday support a new approach to deciding who should receive cholesterol-lowering statin drugs, concluding that the more expansive guidelines issued in 2013 may avert tens of thousands of heart attacks, strokes and deaths and that they are cost-effective.

Published in the Journal of the American Medical Association, the research supports the guidelines issued by the American Heart Association and the American College of Cardiology that called for a sea change in the way doctors determine who should be put on the highly effective heart drugs.

Instead of focusing on the level of a person's low-density lipoproteins -- the so-called "bad" cholesterol -- the groups proposed a formula that considers age, weight, blood pressure and other factors, such as whether patients smoke or have diabetes, to predict whether they have at least a 7.5 percent chance of having a heart attack or stroke in the next decade.

That approach would put 8 to 12 million more people on statins, depending on the estimate, and drew criticism from experts who argued that it overestimated risk, needlessly exposing people to unnecessary costs and some side-effects of the drugs. Roughly a quarter of Americans aged 45 and older already take statins, which include familiar brands such as Lipitor and Zocor.

The studies released Tuesday counter the critics' arguments. In an accompanying editorial that assessed the research, two other physicians wrote that the "available evidence indicates that statins are both effective and cost-effective for primary prevention, even among low-risk individuals."

To determine the effectiveness of the new approach, researchers from Massachusetts General Hospital and elsewhere looked at offspring of the famous Framingham Heart Study. (One drawback of that approach is that it limits their conclusions to whites, according to Udo Hoffmann, a physician in MGH's cardiology division and one of the researchers.)

They determined that people who would be newly eligible for statins under the 2013 guidelines had a similar risk of a heart attack, stroke or death as those receiving them under the old guidelines. By expanding statin use, they wrote, 41,000 to 63,000 such incidents could be prevented in the U.S. population over a 10-year period.

The new guidelines "were associated with greater accuracy and efficiency in identifying increased risk" of those incidents when compared with the older approach, which was issued in 2004, the researchers wrote.

In a separate paper, researchers from Harvard's T.H. Chan School of Public Health and elsewhere concluded that the 7.5 percent risk for cardiovascular events is a cost-effective threshold using standard cost and longevity measures. In fact, they argued, it could be too conservative; people with even a 3 percent or 4 percent risk of suffering heart attacks or strokes could be put on statins cost-effectively.

"Our paper is very important for the individual patient," Hoffman said in an interview. "The cost-effectiveness analysis is very important for the policymakers."