Low HDL cholesterol the biggest modifiable risk for cardiovascular disease in patients with HIV (updated)

Low HDL cholesterol is a bigger risk factor for cardiovascular disease in HIV-positive patients than smoking, total cholesterol, blood pressure or sex, Irish investigators report in the online edition of AIDS.

The researchers found that low HDL (high-density lipoprotein) cholesterol was second only to age as a risk factor for cardiovascular disease (CVD).

“Our data highlight the important contribution of low HDL-c to CVD [risk in HIV-infected patients,” comment the investigators.

HDL cholesterol is often referred to as “healthy cholesterol” and adequate amounts of it have long been associated with a lower risk of cardiovascular disease and other illnesses.

There is a high prevalence of low HDL cholesterol in patients with HIV. The reasons are unclear, but could include the effects of HIV, or the side-effects of some antiretroviral drugs.

Investigators at the Mater Misericordiae University Hospital in Dublin wished to determine the contribution of low HDL-cholesterol to cardiovascular risk in their HIV-positive patients.

They therefore performed a cross-sectional study, monitoring HDL-cholesterol levels and other  established cardiovascular risks in 127 patients who received care at the hospital between 2008 and 2010.

The median age of the patients was 37, two-thirds were men, and 58% were white. The median CD4 cell count was 378 cells/mm³ and 65% of patients were taking antiretroviral therapy, with 83% of these individuals having an undetectable viral load.

Many of the patients had well-known risk factors for cardiovascular disease. Over a third (38%) were smokers, 20% had a family history of cardiovascular disease, and 11% had high blood pressure.

Cholesterol monitoring showed that 3% of individuals had elevated total -cholesterol, 5% had high LDL (low density lipoprotein)-cholesterol - often referred to as “bad” cholesterol -  and 53% had low HDL-cholesterol.

Using the Framingham scale, 110 patients were assessed as having a low ten-year risk of cardiovascular disease, with twelve individuals having a moderate risk, and five a high risk.

The investigators calculated that the biggest single risk factor for cardiovascular disease in their patients was age. This accounted for 41% of the risk.

However, the next most important factor was low HDL cholesterol, which was responsible for 18% of the risk. This far exceeded the risk attributed to smoking (7%), total cholesterol (4%), and gender (2%).

Using a mathematical model, the researchers showed that boosting levels of HDL cholesterol had the potential to lead to health benefits..

An increase in HDL cholesterol levels by 20% would mean that five patients who were previously classified as having a moderate ten-year risk of cardiovascular disease were reclassified as having a low risk, and one patient was moved from the high to moderate risk group.

If HDL cholesterol levels were increased by between 20%-40% then twice as many patients had their risk downgraded.

The investigators calculated that this would have an impact on rates of cardiovascular disease: a 20% increase would mean 1.26 fewer cardiovascular events over ten years, and a 40% increase would prevent 2.41 events over a similar time period.

“In a cohort of HIV-infected patients HDL-c contributed more to CVD risk than smoking, total cholesterol, blood pressure and sex,” comment the investigators.

They acknowledge that a limitation of the study was its small sample size. However, they stress their cohort was “representative of a contemporary HIV-infected population.”

The investigators conclude “further research is warranted, in order to explain why HDL-c is low in HIV-infected patients and to identify potential therapeutic targets.”