Having a high level of HDL cholesterol - the good cholesterol - is more important than having a low level of LDL - the bad cholesterol - in protecting individuals from heart attack, according to a study published in the March issue of American Heart Journal by researchers from the Indiana University School of Medicine and pharmaceutical company GlaxoSmithKline, Inc.
The researchers looked at the history of heart disease, age, sex, race, weight and other heart disease risk factors in almost 7,000 patients. The patients were predominately inner city residents and included a large number of African Americans, women, smokers and overweight people. The researchers found the strongest predictor of future heart attack was previous heart disease; age was the second strongest predictor and the third strongest predictor was HDL level.
"Most of the drugs that lower LDL also tend to raise HDL so until our study, when a person's health improved, you couldn't tell if that was due to lowering of the LDL or raising the HDL level," says study senior author William Tierney, M.D., IU Chancellor's Professor of Medicine and a Regenstrief Institute, Inc. research scientist. "We now know that more good cholesterol is more important than less bad cholesterol.
"Having a high total cholesterol reading may not be bad, in fact it may be good if it's the HDL component which is high. Conversely, a low total cholesterol reading, is not necessarily good because it can hide a low HDL level," said Dr. Tierney.
This study was repeated with stroke as the outcome rather than heart disease, and the same results were the same: HDL cholesterol was a strong predictor of stroke, and the LDL cholesterol was not.
Current guidelines for treating cholesterol focus only on LDL cholesterol. That's not enough: they should focus on both HDL and LDL, according to Dr. Tierney. He calls for guidelines to be revised to encourage physicians and their patients to pay closer attention to HDL cholesterol.