Bipolar disorder in people with HIV: A nationwide, population-based matched case-control and matched cohort study

OBJECTIVES: To assess whether bipolar disorders are associated with the risk of HIV infection and whether the risk of bipolar disorders is increased among people with HIV (PWH) and their siblings.

DESIGN: Nationwide, population-based, combined matched nested case-control and cohort study of PWH of Danish origin (1995-2021), a comparison cohort from the background population, matched on date of birth and sex, and sibling cohorts.

METHODS: Conditional logistic regression and Cox regression was used to calculate adjusted odds ratios (aORs) for HIV infection and hazard ratios among PWH for bipolar disorder and receipt of lithium.

RESULTS: We included 5322 PWH and 53 220 comparison cohort members. In the case-control study, bipolar disorder was associated with an increased risk of HIV infection [aOR: 1.9, 95% confidence interval (CI): 1.2-3.0], especially when injection drug use was the route of infection (aOR: 7.6, 95% CI: 2.0-28.9). In the cohort study, we observed an increased risk of bipolar disorders among PWH, especially in the first 2 years of observation (hazard ratio: 4.2, 95% CI: 2.4-7.4), whereas the risk of receipt of lithium was lower and the CI crossed 1. The 20-year risk of bipolar disorders for PWH was approximately 1%. Siblings of PWH also had an increased risk of bipolar disorder but not to the same degree as PWH and not of receipt of lithium.

CONCLUSION: Bipolar disorders are associated with the risk of HIV infection, and PWH have increased risk of bipolar disorder and receipt of lithium beyond what familial factors could explain.