Johns Hopkins researchers have developed a more accurate way to calculate the so-called "bad" form of blood fat that can lead to hardening of the arteries and increase the risk of heart attack and stroke.
 

Details about the test, which the scientists said would give patients and their doctors a much more accurate assessment of LDL cholesterol, emerged this week as new questions are being raised about an online calculator designed to help doctors assess heart disease.
 

According to the New York Times, the calculator is flawed and could result in millions of people being prescribed statin drugs who don’t need them. In response to the finding by two Harvard Medical School professors, a past president of the American College of Cardiologists has called for the implementation of the new guidelines announced with the calculator to be stopped and for further study to be conducted.
 

"The standard formula that has been used for decades to calculate LDL cholesterol often underestimates LDL where accuracy matters most — in the range considered desirable for patients at high risk for heart attack and stroke," said Seth S. Martin, M.D., a cardiology fellow at the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease. Martin who helped develop the new test, detailed in the Journal of the American Medical Association.
 

Higher levels of LDL cholesterol have been shown to raise the risk of plaque accumulating in heart arteries. Since 1972, a formula called the Friedewald equation has been used to gauge LDL cholesterol, but it is an estimate and not a direct measurement, and is widely used by physicians to assess their patients' risk and determine treatment.
 

The Friedewald equation estimates LDL cholesterol by calculating total cholesterol minus HDL cholesterol minus triglycerides divided by five. But the Johns Hopkins researchers say that formula applies a one-size-fits-all factor of five to everyone. A more accurate method would take into consideration specific details about a person's cholesterol and triglyceride levels.
 

Using a database of blood lipid samples from more than 1.3 million Americans, the researchers developed an entirely different system and created a chart that uses 180 different factors to more accurately calculate LDL cholesterol and individualize the assessment for patients.
 

"We believe that this new system would provide a more accurate basis for decisions about treatment to prevent heart attack and stroke," said Dr. Martin.