Risk of Multiple Sclerosis in People Living with HIV: An International Cohort Study

Abstract

ObjectiveThere has been interest in a possible negative association between HIV and multiple sclerosis (MS). We aimed to compare the risk of MS in a cohort of individuals living with HIV to that in the general population.MethodsPopulation‐based health data were accessed for 2 cohorts of HIV‐positive persons from Sweden and British Columbia, Canada. Incident MS was identified using MS registries or a validated algorithm applied to administrative data. Individuals with HIV were followed from 1 year after the first clinical evidence of HIV or the first date of complete administrative health data (Canada = April 1, 1992 and Sweden = January 1, 2001) until the earliest of incident MS, emigration, death, or study end (Canada = March 31, 2020 and Sweden = December 31, 2018). The observed MS incidence rate in the HIV‐positive cohort was compared to the expected age‐, sex‐, calendar year‐, income‐specific, and region of birth‐specific rates in a randomly selected sample of >20% of each general population. The standardized incidence ratio (SIR) for MS following the first antiretroviral therapy exposure (“ART‐exposed”) was also calculated.ResultsThe combined Sweden‐Canada cohort included 29,163 (75% men) HIV‐positive persons. During 242,248 person‐years of follow‐up, 14 incident MS cases were observed in the HIV‐positive cohort, whereas 26.19 cases were expected. The SIR for MS in the HIV‐positive population was 0.53 (95% confidence interval [CI] = 0.32–0.90). The SIR for MS following the first ART exposure was 0.55 (95% CI = 0.31–0.96).InterpretationThis international population‐based study demonstrated a lower risk of MS among HIV‐positive individuals, and HIV‐positive ART‐exposed individuals. These findings provide support for further exploration into the relationship among HIV, ART, and MS. ANN NEUROL 2023