Long-term mortality and late sequelae after bacterial meningitis: A matched cohort study with six decades of follow-up

OBJECTIVES: Investigate long-term consequences of bacterial meningitis. METHODS: A matched cohort study linking a clinical database on paediatric and adult patients with bacterial meningitis in Denmark from 1966 to 1977 with national registries until 2025. Patients were matched 1:5 with population controls and included along with sibling controls. Hazard ratios (HR) with 95% confidence intervals (CI) were estimated for mortality from 1 year after admission and for neurological and otological disorders from 20 years after admission. RESULTS: We included 724 patients with a median age of 17 years. Initial disease and treatment characteristics were not associated with long-term mortality. Patients had higher mortality than 3620 population controls (HR 1.33 [95% CI 1.16-1.53]) and 695 siblings of patients had higher mortality than 3313 siblings of population controls (HR 1.42 [95% CI 1.06-1.91]). Patients had an increased risk of cerebrovascular diseases (HR 1.46 [95% CI 1.04-2.04]), migraine and other headache syndromes (HR 1.76 [95% CI 1.11-2.80]), and hearing loss (HR 1.56 [95% CI 1.13-2.17]), whereas the risk of dementia and residence in 24-hour care facilities was comparable to population controls. CONCLUSIONS: Patients with bacterial meningitis had modest long-term excess mortality, potentially attributable to familial factors. We found no association with neurodegenerative diseases occurring late after bacterial meningitis.