HIV infection and incidence of ischemic stroke

Abstract

Objective: To determine the association of HIV infection and immunodeficiency with incidence of ischemic stroke. Design: Cohort study of HIV-positive and matched HIV-negative adult Kaiser Permanente Northern and Southern California (KPNC and KPSC, respectively) members during 1996–2011 (KPNC) or 2000–2011 (KPSC). Methods: We used Poisson models to obtain rate ratios for incident ischemic stroke associated with HIV infection, both overall and stratified by CD4+ cell counts (cells/μl) and HIV RNA copies (copies/ml), with HIV-negative individuals as the reference group. We also obtained rate ratios for risk factors in the HIV-positive subset. Results: Among 24 768 HIV-positive and 257 600 HIV-negative individuals, the ischemic stroke rate per 100 000 person-years was 125 (n = 151 events) for HIV-positive and 74 (n = 1128 events) for HIV-negative individuals, with an adjusted rate ratio of 1.4 [95% confidence interval (CI) 1.2–1.7). Compared with HIV-negative individuals, HIV-positive individuals with recent CD4+ cell counts of 500 cells/μl at least (rate ratio 1.0, 95% CI 0.8–1.4) or recent HIV RNA less than 500 copies/ml (rate ratio 1.1, 95% CI 0.9–1.4) had no excess risk of ischemic stroke, with similar results for HIV-positive individuals with nadir CD4+ cell counts of 500 cells/μl at least (rate ratio 1.4, 95% CI 0.8–2.2) or 200–499 cells/μl (rate ratio 1.2, 95% CI 0.9–1.5). Among HIV-positive individuals only, recent CD4+ cell count less than 200 cells/μl (rate ratio 2.5, 95% CI 1.3–4.6) was associated with an increased risk of ischemic stroke after adjustment for recent HIV RNA and nadir CD4+ cell count, whereas recent HIV RNA and nadir CD4+ were not independent risk factors. Conclusion: Ischemic stroke incidence in HIV-positive individuals with high CD4+ cell count or low HIV RNA is similar to that of HIV-negative individuals.