A study supported by the National Institutes of Health found that high-density lipoprotein (HDL) cholesterol, often called “good cholesterol,” may not be as effective as scientists once thought at uniformly predicting the risk of cardiovascular disease among adults of different racial and ethnic origins.
A study published in Journal of the American College of Cardiology, found that while low HDL cholesterol predicted an increased risk of heart attacks or related deaths for white adults—a long-recognized association—the same was not true for black adults. In addition, higher HDL cholesterol was not associated with a reduced risk of cardiovascular disease in either group.
“The goal was to understand this long-established association that marks HDL as good cholesterol, and if that holds true across ethnic groups,” said Natalie Pamir, Ph.D., senior author of the study and associate professor of medicine at the Cardiovascular Institute. Knight at Oregon Health & Science University, Portland. “It has been recognized that low HDL cholesterol is harmful, regardless of race. Our study tested these assumptions.’
To do this, Pamir and her colleagues reviewed data from 23,901 US adults who participated in the Reasons for Geographic and Racial Disparities in Stroke (REGARDS) study. The previous studies that shaped the notion of “good” cholesterol levels and heart health were conducted in the 1970s through studies involving mostly white adult study participants. In the current study, researchers were able to look at how cholesterol levels in middle-aged black and white adults without heart disease who lived across the country correlated with future cardiovascular events.
Study participants who participated in REGARDS from 2003 to 2007 analyzed information collected over 10 to 11 years. Black and white study participants had similar characteristics, such as age, cholesterol levels and major risk factors for heart disease, including diabetes, high blood pressure or smoking. During that time, 664 black adults and 951 white adults experienced a heart attack or heart attack-related death. Adults with elevated LDL cholesterol and triglycerides had a modestly increased risk of cardiovascular disease, consistent with findings from previous studies.
However, the study was the first to find that lower HDL cholesterol only predicted an increased risk of cardiovascular disease for white adults. It also expands on findings from other studies showing that high HDL cholesterol levels are not always associated with reduced cardiovascular events. The REGARDS analysis was the largest US study to show that this was true in both black and white adults, suggesting that higher-than-optimal amounts of “good” cholesterol may not have cardiovascular benefits in either group.
“What I hope this type of research shows is the need to rethink the algorithm for predicting cardiovascular disease risk,” Pamir said. “This could mean that in the future, our doctors won’t be patting us on the back for having higher HDL cholesterol.”
Pamir explained that researchers are studying the role of HDL cholesterol in supporting heart health and exploring different theories. One is quality over quantity. That is, rather than having more HDL, the quality of HDL’s function — in collecting and transporting excess cholesterol from the body — may be more important for maintaining cardiovascular health.
They also take a microscopic look at the properties of HDL cholesterol, including analyzing hundreds of proteins involved in cholesterol transport and how different associations based on a single protein or groups of proteins can improve cardiovascular health predictions.
“HDL cholesterol has long been an enigmatic risk factor for cardiovascular disease,” explained Sean Coady, deputy chief of epidemiology in the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI). “These findings suggest that further investigation into the epidemiology of lipid metabolism is warranted, particularly in terms of how race may modify or mediate this relationship.”
The authors conclude that in addition to supporting current and future studies with different populations to examine these associations, the results indicate that CVD risk calculators using HDL cholesterol may lead to inaccurate predictions for black adults.
“When it comes to heart disease risk factors, they can’t be limited to one race or ethnicity,” Pamir said. “They should be applied to everyone.”
The REGARDS study is jointly funded by the National Institute of Neurological Disorders and Stroke and the National Institute on Aging and has received additional support from the NHLBI.