For decades, high-density lipoprotein (HDL) cholesterol has been dubbed “good cholesterol” because of its role in moving fats and other cholesterol molecules out of artery walls.
People with higher HDL cholesterol levels tend to have lower rates of cardiovascular disease, studies have shown.
In a new study, researchers analyzed data on more than 15,000 people to better understand the association between HDL cholesterol, heart attacks, and strokes in diverse populations.
They found that the number of HDL particles, a little-used measurement of HDL, is a more reliable predictor of heart attack and stroke risk than the standard HDL cholesterol metric.
The research was conducted by UT Southwestern scientists.
According to the Centers for Disease Control and Prevention, heart disease is the leading cause of death in the U.S.
More than 12% of adults in the U.S. have high total cholesterol levels, and more than 18% have what’s currently considered low levels of HDL cholesterol.
Cholesterol is a waxy substance that is used by the body to make hormones and keep cells functioning properly.
But when low-density lipoprotein (LDL) cholesterol levels are too high, cholesterol can accumulate inside blood vessels, forming deposits called plaques.
These plaques can eventually lead to blood vessel blockages that cause heart attacks or strokes.
HDL cholesterol helps remove cholesterol from blood vessels. But recent studies have come to mixed conclusions about the association between HDL cholesterol levels and health outcomes.
Previous studies have looked at HDL levels in the population as a whole.
In the study, the team examined information on people who had participated in four large, nationwide studies.
In all, the studies included 15,784 people followed over an average of 8 to 12 years. Their average age was 56 years.
The data included two different measurements of HDL: HDL-P levels tally how many particles of HDL are circulating in the blood.
HDL-C levels, the standard test, instead quantify how much total HDL cholesterol is inside those particles.
Since the number of HDL particles may vary with regards to how much cholesterol they contain, the two measurements can be quite different and are only moderately correlated.
The team found people with the highest HDL-P levels, above 37 mmol/L, had a 37% lower risk of heart attack and a 34% lower risk of stroke than those who had the lowest HDL-P levels.
In women, this association was stronger – those with the highest HDL-P levels had a 49% reduction in heart attacks and a 46% reduction in stroke.
While HDL-C predicted heart attack risk in the overall pool of people as well as in women, it was not linked to stroke.
When the researchers homed in on black participants, the results were different – neither HDL-C nor HDL-P was linked to a black person’s risk of a heart attack.
A better understanding of how HDL can help predict disease, and how that association varies among populations, is vital to lower rates of cardiovascular disease, the researchers say.
One author of the study is Anand Rohatgi, M.D., an associate professor of internal medicine at UTSW.
The study is published in the journal Circulation.
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