Niacin May Improve Blood Vessel Function in People with HIV

		SUMMARY: HIV positive people treated with extended-release niacin for 12 weeks demonstrated improved ability of the endothelial lining of blood vessels to expand and contract, a sign of good function that is lost with the development of atherosclerosis, according to a study described in the April 24, 2010 issue of AIDS.

By Liz Highleyman

Research indicates that people with HIV are more prone to cardiovascular disease, which may be associated with antiretroviral therapy (ART), inflammation due to ongoing viral replication, or other factors that are not yet fully understood. Impaired endothelial function is an early stage in the progression of atherosclerosis, or "hardening of the arteries."

Dominic Chow from the University of Hawaii and colleagues conducted a study to assess the short-term effects of extended-release niacin on endothelial function in HIV positive people with low high-density lipoprotein (HDL) "good" cholesterol levels. HDL removes lipids from blood vessels and therefore has a protective effect, while low-density lipoprotein (LDL) "bad" cholesterol deposits fats on artery walls and increases the risk of heart disease.

This small controlled study included 19 HIV positive participants; most (89%) were men, the median age was 50 years, and about half were white. All were on stable ART, 95% had HIV viral load < 50 copies/mL, and the median CD4 cell count was high at 493 cells/mm3. Participants had HDL < 40 mg/dL and LDL < 130 mg/dL. None were taking lipid-lowering medications.

Patients were randomly assigned to receive or not receive extended-release niacin; there was no placebo arm. Treatment started at 500 mg/night and was titrated up to 1500 mg/night for 12 weeks. The researchers measured flow-mediated vasodilation in the brachial artery of the upper arm, or how much the arteries expand in response to increased blood flow.

Results

	Participants receiving extended-release niacin experienced a median HDL cholesterol increase of +3.0 mg/dL, compared with a loss of -1.0 mg/dL in the control group (P = 0.04).
	The median change in flow-mediated dilation was +0.91% in the extended-release niacin arm versus -0.48% in the control arm, but the difference did not reach statistical significance (P = 0.67).
	At the end of the study period, however, flow-mediated dilation was improved in the niacin arm compared with the control arm after adjusting for baseline differences in flow-mediated dilation and HDL, a difference just meeting the criteria for significance (6.4% vs 2.7%, respectively; P = 0.048).
	The difference in improvement in flow-mediated dilation was more significant for patients with low baseline HDL.

This pilot study, the investigators concluded, demonstrates that short-term niacin therapy "could improve endothelial function in HIV-infected patients with low HDL cholesterol."

"Our study is consistent with recent studies on individuals without HIV infection, showing that interventions targeted at raising HDL cholesterol may have vascular benefits," they elaborated in their discussion. "Our finding supports the paradigm that niacin-induced increases in HDL cholesterol contribute to improvements in endothelial function in participants with low HDL cholesterol."

Hawaii Center for AIDS, University of Hawaii John A. Burns School of Medicine, University of Hawaii, Honolulu, HI; Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, University of Wisconsin, Madison, WI; Public Health Sciences, University of Hawaii, Honolulu, HI.

5/25/10

Reference
DC Chow, JH Stein, TB Seto, and others. Short-term effects of extended-release niacin on endothelial function in HIV-infected patients on stable antiretroviral therapy. AIDS 24(7): 1019-1023 (Abstract). April 24, 2010.