HDL High and Low Levels May Cause Premature Death

High and low levels of high-density lipoprotein (HDL) cholesterol may increase a person's risk of premature death although commonly touted as “good cholesterol” that helps to reduce risk of both stroke and heart attacks.

Cholesterol is a fatty substance found in blood that can narrow and block heart vessels, causing cardiovascular disease and stroke and for years, HDL cholesterol has been credited with helping to remove plaque-building “bad cholesterol” from arteries.

Scientists at the Washington University School of Medicine (St. Louis, MO, USA) studied kidney function and HDL cholesterol levels in a cohort of more than 1.7 million male veterans from October 2003 through September 2004 and then followed participants until September 2013 or until death. They sought to characterize the relationship of HDL cholesterol and risk of death and examine the association by estimated glomerular filtration rate (eGFR) levels.

The team found that patients with low HDL cholesterol and low eGFR had a higher burden of comorbid illnesses. In adjusted survival models, compared with the referent group of patients with low HDL cholesterol (≤25 mg/dL), intermediate HDL cholesterol levels (>25 to <34, ≥34 to ≤42, and >42 to <50 mg/dL) were associated with lower risk of death across all levels of eGFR. The lower risk was partially abrogated in those with high HDL cholesterol (≥50 mg/dL), and the risk of death was similar to the referent category among those with eGFR<30 or ≥90 mL/min per 1.73 m2.

There was a significant interaction between eGFR and HDL cholesterol in that lower eGFR attenuated the salutary association of HDL cholesterol and risk of death. Presence of coronary artery disease attenuated the lower risk of high HDL cholesterol and all-cause mortality in those with eGFR ≥60 mL/min per 1.73 m2.

Ziyad Al-Aly, MD, an assistant professor of medicine and the study's senior author, said, “The findings surprised us. Previously it was thought that raised levels of the good cholesterol were beneficial. The relationship between increased levels of HDL cholesterol and early death is unexpected and not fully clear yet. This will require further study.” The study was published in the August 2016 issue of the Clinical Journal of the American Society of Nephrology.

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