Excess HDL Cholesterol May Increase Mortality Risk

Findings from a new study published by the European Heart Journal suggest that high levels of high-density lipoprotein (HDL)—also known as good cholesterol—may increase the risk of mortality.

The authors found that those with extremely high levels of HDL may have a 65% increased mortality rate among those with normal HDL levels. These results suggest that the way HDL cholesterol is perceived may need to be explored further.

For men with extremely high HDL cholesterol levels, the authors found that their risk of mortality was 106% higher compared with patients who have normal cholesterol levels. Similarly, women with high HDL levels had a 68% increased risk of mortality, according to the study.

“These results radically change the way we understand ‘good’ cholesterol,” said study author Børge Nordestgaard, MD, DMSc. “Doctors like myself have been used to congratulating patients who had a very high level of HDL in their blood. But we should no longer do so, as this study shows a dramatically higher mortality rate.”

Included in the study were data for 116,000 patients and mortality data from the Danish Civil Registry System. Participants were followed for an average of 6 years, in which more than 10,500 deaths occurred.

The authors evaluated mortality rate based on deaths and medical data, according to the study. Of these patients, 0.4% of men and 0.3% of women had extremely high levels of HDL, and 1.9% of men had very high levels.

While patients with extremely high HDL cholesterol levels were found to have the most significantly increased mortality risk, the authors also found that men with very high levels had a 36% increased risk of mortality.

Notably, the researchers found that those with extremely low levels of HDL had an increased risk of mortality.

The group with medium levels of HDL was observed to have the lowest risk of mortality. This level was 1.9-mmol/L in men and 2.4-mmol/L in women, according to the study.

Previous studies have found a link between HDL cholesterol and excessive mortality in certain individuals. The new study is the first to establish this link to the general population.

The authors hope that the findings alter the perception of HDL, according to the study. However, the findings do not explain why individuals with extremely high or low levels of HDL have increased mortality.

“It appears that we need to remove the focus from HDL as an important health indicator in research, at hospitals and at the general practitioner,” Dr Nordestgaard said. “These are the smallest lipoproteins in the blood, and perhaps we ought to examine some of the larger ones instead. For example, looking at blood levels of triglyceride and LDL, the ‘bad’ cholesterol, are probably better health indicators.”