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Chronic HIV and HCV Swell Stroke Risk in Veterans Aging Cohort
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17th Conference on Retroviruses and Opportunistic Infections, February 16-19, 2010, San Francisco
Mark Mascolini
HIV infection with or without hepatitis C virus (HCV) infection raised the risk of stroke in the Veterans Aging Cohort [1]. "This association may have been underappreciated" earlier, the VA team suggested, "because of excessive risk of death in this patient population."
Previous research associated HIV infection with an elevated risk of hemorrhagic stroke [2], but the threat of stroke in people with long-term infection remains poorly understood. HCV also contributes to cardiovascular risk in people with HIV [3].
To gauge the impact of ongoing HIV and HCV infection on stroke, Jason Sico and VA coworkers assessed 8579 men in the Veterans Affairs Aging Cohort Virtual Cohort (VACS-VC), 738 coinfected with HIV and HCV, 1687 infected only with HIV, 701 infected only with HCV, and 5453 with neither virus.
Median follow-up measured 7.3 years, during which 160 men had strokes and 1181 died. Mortality adjusted for age and race measured 60.6 per 1000 person-years in HIV/HCV-coinfected men, 39.0 in HIV-monoinfected men, 20.5 in HCV-monoinfected men, and 12.9 in men with neither infection. Stroke incidence per 1000 person-years, also adjusted for age and race, was also highest in coinfected men:
· HIV and HCV: 6.99 (95% confidence interval [CI] 6.88 to 7.30)
· HIV only: 2.93 (95% CI 2.79 to 3.07)
· HCV only: 4.13 (95% CI 3.96 to 4.29)
· Neither virus: 2.38 (95% CI 2.33 to 2.44)
The investigators devised two models to calculate hazard ratios for stroke. Model 1 factored in age, race, education, body mass index, hypertension, diabetes, smoking, hypercholesterolemia, alcohol abuse, cocaine abuse and dependence, and congestive heart failure in the follow-up period before stroke, with death as a censoring event. Model 2 considered death as a competing risk and adjusted for all variables listed for model 1.
Compared with uninfected men, HIV alone independently doubled the risk of stroke in model 2 but not model 1 (HR 2.13, 95% CI 1.65 to 2.75), while the association between HCV and stroke was strong but not independent in model 2 (HR 1.44, 95% CI 0.99 to 2.11). HIV/HCV coinfection independently doubled the stroke risk in both model 1 (HR 2.08, 95% CI 1.31 to 3.31) and model 2 (HR 2.21, 95% CI 1.62 to 3.02).
The VA team did not spell out demographic and behavioral variables of their population, but VACS cohorts generally include a high proportion of blacks and a share of alcohol and drug abusers. Without further detail, it is risky to apply these results to other HIV populations.
References
1. Sico J, Chang J, Freiberg M, et al. HIV Infection, hepatitis C infection, and the risk of stroke in the Veterans Aging Cohort Study Virtual Cohort. 17th Conference on Retroviruses and Opportunistic Infections. February 16-19, 2010. San Francisco. Abstract 668.
2. Freiberg MS, Cheng DM, Kraemer KL, et al. The association between hepatitis C infection and prevalent cardiovascular disease among HIV-infected individuals. AIDS. 2007;21:193-197.
3. Justice AC, Zingmond DS, Gordon KS, et al. Drug toxicity, HIV progression, or comorbidity of aging: does tipranavir use increase the risk of intracranial hemorrhage? Clin Infect Dis. 2008;47:1226-1230.
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