Incidence of autoimmune diseases in people living with HIV compared to a matched population: a cohort study.

The objective of this paper is to estimate incidence and relative risk of autoimmune conditions in patients living with HIV compared to an HIV-negative matched population. We conducted a retrospective study in the medico-administrative database of the province of Québec, Canada. All HIV-positive patients treated with antiretrovirals were matched to up to 4 HIV-negative controls for age, sex, and period of follow-up. The following autoimmune conditions were identified using medical billing codes: vasculitis, hematological (immune thrombocytopenic purpura and immune hemolytic anemia), ankylosing spondylitis, psoriasis and psoriatic arthritis, inflammatory bowel disease and associated arthritis, connectivitis, and systemic lupus erythematosus. Incidence rates and adjusted hazard ratios (aHR) were obtained using survival models. A total of 4245 HIV-positive patients were matched to 16493 HIV-negative patients. Autoimmune diseases were diagnosed in 407 (9.6%) HIV-positive and 508 (3%) HIV-negative patients. The aHR for autoimmune diseases associated to HIV was 2.40 95% CI [2.10-2.75]. The strongest associations were seen for hematological disorders (aHR 8.34 95% CI [6.13-11.36]), followed by ankylosing spondylitis (1.82 95% CI [1.03-3.21]), inflammatory bowel disease and associated arthritis (1.80 95% CI [1.37-2.35]), psoriasis and associated arthritis (1.69 95% CI [1.23-2.33]), and rheumatoid arthritis (1.51 95% CI [1.08-2.11]).We found no association between HIV and the incidence of vasculitis, connectivitis, and systemic lupus erythematosus, but the number of cases for these diseases were few. Autoimmune diseases are more frequent among people living with HIV than age and sex-matched population-based controls. Key Points • Strength: The major strength of this study is its large sample size of 4200 people treated as HIV infection, matched to 16000 HIV negative for sex and age. • Novelty: We found that people living with HIV were more than twice as likely to suffer from auto-immune diseases than their matched counterparts.