March 26, 2013

Commonly used cholesterol calculation underestimates the heart disease danger for many at high risk




Researchers suggest a different method of assessing risk after examining data on 1.3 million Americans

In what promises to be an eye-opener for many doctors and patients who routinely depend on cholesterol testing, a study led by researchers at the Johns Hopkins University School of Medicine found that the standard formula used for decades to calculate low-density lipoprotein (LDL) cholesterol levels is often inaccurate. Of most concern, the researchers say, is their finding that the widely used formula underestimates LDL where accuracy matters most — in the range considered desirable for high-risk patients. Results of the study are published in an online article, ahead of print, in the Journal of the American College of Cardiology.

LDL is known as the "bad' cholesterol, with higher numbers signaling greater risk of plaque accumulating in heart arteries and having a heart attack. Since 1972, a formula called the Friedewald equation has been used to gauge LDL cholesterol. It is an estimate rather than an exact measurement. However, physicians use the number to assess their patients’ risk and determine the best course of treatment.