Role of pre-stroke immunity in ischemic stroke mechanism among patients with HIV.

Individuals with HIV are at a higher risk of stroke compared to uninfected populations. The role of HIV-related immunosuppression in stroke mechanism is uncertain. Our aim is to test the hypothesis that stroke mechanisms among HIV+ individuals vary according to preceding CD4 counts. We carried out a retrospective chart review of inpatient admissions for ICD-9 defined ischemic events (TIA or stroke) in HIV+ individuals from 2002 to 2016 at a tertiary care center. Stroke mechanisms were ascertained based on radiographic and clinical presentation, and adjudicated by the treating team and confirmed separately by a vascular neurologist. Vascular risk factors, use of antiretroviral drugs (ARVs), nadir CD4 and current CD4 counts (cells/mm3) were captured to build logistic regressions and generalized linear models to calculate the odds ratios (OR) and beta estimates with their respective 95% confidence intervals. We found that among 115 cases (median age 52, 64% men), stroke mechanisms were 22% due to large artery atherosclerosis (LAA), 17% small artery disease, 16% infectious, 8% cardioembolic, 21% cryptogenic, and 16% other etiologies. The median nadir CD4-count was 153 (IQR 22-274), and 312 (IQR 88-518) at the time of stroke, and 53% were on ARVs. LAA was more common with longer HIV infection (OR 1.1 per year, 1.0-1.2) and nadir CD4 counts <200 (OR 6.7, 1.4-31.9). Stroke due to LAA was associated with higher CD4 count the year prior to stroke (B = 0.009, P = 0.06 for the interaction) independent of CD4 nadir <200 (B = 1.88, P = 0.035). We concluded that in this sample, LAA was the most frequent stroke mechanism among HIV+ individuals with nadir CD4 < 200 but higher CD4 counts near the time of stroke. Determining the association between pre-stroke immune status and stroke mechanisms may allow a targeted approach to stroke prevention.