SUMMARY: HIV positive veterans had about twice the risk of having a stroke as their HIV negative counterparts, and being coinfected with hepatitis C virus (HCV) further elevated the risk, but hepatitis C alone conferred an insignificant increase, according to a poster presented at the 17th Conference on Retroviruses & Opportunistic Infections (CROI 2010) last month in San Francisco. The researchers suggested stroke death may have been underestimated in the past.

By Liz Highleyman

Numerous prior studies have found associations between cardiovascular disease in both people with HIV and those with chronic hepatitis C, but most of this research has focused on heart outcomes such as myocardial infarction rather than strokes. Less research has looked at cardiovascular outcomes in HIV/HCV coinfected people.

Jason Sico and fellow investigators with the Veterans Aging Cohort Study (VACS) analyzed data from 8579 participants (all men) in the VACS Virtual Cohort who took part in the 1999 Large Health Study of Veteran Enrollees. Within this group, 1687 (20%) had HIV alone, 701 (8%) had HCV alone, 738 (9%) were HIV/HCV coinfected, and 5453 (64%) had neither virus. None of the participants had cardiovascular diseases or cancer at baseline.

The researchers analyzed data on HIV and HCV status, stroke risk factors, incidence of stroke, and mortality collected from January 2000 to July 2007. The median follow-up period was 7.3 years. Diagnosis of stroke was based on inpatient and outpatient ICD-9 codes.

Results

	A total of 160 strokes were reported during the follow-up period:
	HIV+/HCV+: 29 (18.1% of all strokes); adjusted incidence rate 6.99 per 1000 person-years; HIV+/HCV-: 28 (17.5%); 2.93 per 1000 person-years; HCV+/HIV-: 19 (11.9%), 4.13 per 1000 person-years; HIV-/HCV-: 84 (52.5%), 2.38 per 1000 person-years.
	A total of 1181 deaths were reported:
	HIV+/HCV+: 252 (21.3% of all deaths); adjusted mortality rate 60.6 per 1000 person-years; HIV+/HCV-: 380 (32.2%); 39.0 per 1000 person-years; HCV+/HIV-: 94 (8.0%); 20.5 per 1000 person-years; HIV-/HCV-: 455 (38.5%); 12.9 per 1000 person-years.
	In a model adjusting for potential confounding factors including demographics, cardiovascular risk factors, and substance use, the hazard ratios (HR) for strokes were:
	HIV+/HCV+: HR 2.08; HIV+/HCV-: HR 1.34; HCV+/HIV-: HR 1.36; HIV-/HCV-: HR 1.0 (comparison group).
	In a second model adjusting for the same factors but treating death as a competing risk, the hazard ratios were:
	HIV+/HCV+: HR 2.21; HIV+/HCV-: HR 2.13; HCV+/HIV-: HR 1.44; HIV-/HCV-: HR 1.0 (comparison group).
	HIV infection alone was associated with a 2-fold risk of stroke in the second model, though it did not reach statistical significance in the first.
	HCV alone increased the stroke risk more in the second model than the first, but neither reached significance.
	HIV/HCV coinfection more than doubled the stroke risk in both models.

These findings led the investigators to conclude, "Chronic HIV infection with and without hepatitis C coinfection is associated with an increased risk of stroke."

"The risk of stroke in HIV and HIV/HCV infected people may be under-appreciated due to the excess competing risk of death," they continued. "If confirmed in other studies, these findings have important implications for clinical management of those aging with HIV infection.

Yale Sch of Med, New Haven, CT; VA Connecticut Healthcare System, West Haven VAMC, CT; Univ of Pittsburgh Sch of Med, Pittsburgh, PA; Boston Med Ctr, Boston, MA; George Washington Univ Sch of Med and Washington DC VAMC, Washington, DC; David Geffen Sch of Med, Univ of California, Los Angeles and the VA Greater Los Angeles Health Care System, Los Angeles, CA; Emory Univ Sch of Med and Atlanta VAMC, Atlanta, GA; Univ of Pittsburgh, Grad Sch of Public Health, Pittsburgh, PA.

3/5/10

Reference
J Sico, J Chang, M Freiberg, and others. HIV Infection, Hepatitis C Infection, and the Risk of Stroke in the Veterans Aging Cohort Study Virtual Cohort (VACS-VC). 17th Conference on Retroviruses & Opportunistic Infections (CROI 2010). San Francisco. February 16-19, 2010. (Abstract 668).