Do HIV+ People Have Higher Stroke Risk?

SUMMARY A Danish study finds HIV positive people have a higher risk for stroke, increasing with injection drug use and lower CD4 cell count but not antiretroviral therapy overall.

By Liz Highleyman

Several observational studies over the course of the epidemic have found that people with HIV/AIDS have an elevated risk for cardiovascular events including heart attacks and strokes, but data on rates and risk factors have been highly variable and sometimes conflicting.

As described in the June 3, 2011, advance online edition of AIDS, Line Rasmussen from Odense University Hospital and colleagues conducted a study to assess the risk of cerebrovascular events, or strokes, in HIV positive individuals and to evaluate the influence of proven and potential risk factors.

The analysis included all HIV positive people in Denmark, which has a centralized health system that enables comprehensive monitoring. The study also looked at a general population comparison cohort and at parents of both the HIV positive and general population groups. None of the participants had pre-existing brain disease.

The researchers calculated incidence rate ratios (IRR) for cerebrovascular events overall and for events with and without proven risk factors. The analysis was stratified according to history of injection drug use, which has been shown to be a risk factor for strokes among HIV positive and negative people in prior studies.

Most HIV positive participants were on highly active antiretroviral therapy (HAART). The study authors looked at the influence of HIV drugs including protease inhibitors as a class, indinavir (Crixivan), didanosine (ddI, Videx), abacavir (Ziagen, also in the Trizivir and Epzicom coformulation), and tenofovir (Viread, also in the Truvada and Atripla coformulations). Some prior research has linked abacavir to heart attacks and other cardiovascular events, but others have found no such association.

Results

	HIV positive people had an increased risk of cerebrovascular events compared with the general population cohort, a difference that was magnified for injection drugs users (IDUs):
	Non-IDU: adjusted IRR 1.60 for HIV positive vs HIV negative individuals, or 60% higher risk; IDUs: adjusted IRR 3.94 for HIV positive vs HIV negative, or nearly 4 times higher risk.
	Stroke risk was higher both among HIV positive people with and those without proven risk factors.
	Significant predictors of increased stroke risk, in addition to injection drug use, included:
	CD4 count < 200 cells/mm3 before starting combination ART (adjusted IRR 2.26); Exposure to abacavir (adjusted IRR 1.66).
	However, use of protease inhibitors as a class, indinavir, didanosine, tenofovir, and HAART overall had no significant association with stroke risk.
	Parents of HIV positive IDUs had a higher rate of strokes, but this was not the case for the non-IDU group.

Based on these findings, the researchers concluded, "HIV-infected individuals have an increased risk of [cerebrovascular events] with and without proven risk factors."

"The risk is associated with [injection drug use], low CD4 count, and exposure to abacavir, but not with HAART," they continued. "An association with family-related risk factors seems vague except for parents of IDUs."

Investigator affiliations: Department of Infectious Diseases, Odense University Hospital, Odense, Denmark; Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Neurology, Copenhagen University Hospital, Bispebjerg, Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre Hospital, Denmark.

6/14/11

Reference
LD Rasmussen, FN Engsig, H Christensen, et al. Risk of cerebrovascular events in persons with and without HIV: A Danish nationwide population-based cohort study. AIDS (abstract). June 3, 2011 (Epub ahead of print).