Hereditary haemorrhagic telangiectasia and pulmonary arteriovenous malformations in brain abscess patients: a nationwide, population-based matched cohort study.

OBJECTIVES: The extent of hereditary haemorrhagic telangiectasia (HHT) and pulmonary arteriovenous malformations (PAVMs) as a risk factor for brain abscess is unknown. METHODS: Nationwide and population-based registries were used to identify persons with first-time hospitalization for brain abscess (index date) and population controls matched by age, sex and residence (1:10). Accounting for competing risks, cumulative incidence curves of new diagnosis of HHT/PAVM after brain abscess were constructed. Next, Cox regression was used for computation of cause-specific hazard rate ratios (HRRs) adjusted for severe liver disease and congenital heart disease as potential confounders. RESULTS: HHT/PAVM was prevalent before the index date in 2/1384 (0.1%; 95% CI 0.02-0.52) brain abscess patients and 6/13 838 (0.04%; 95% CI 0.02-0.09) matched population controls. After the index date, a new diagnosis of hereditary haemorrhagic telangiectasia or pulmonary arteriovenous malformations was made in 15/1384 brain abscess patients (range 0 days to 17 years) compared with 7/13 812 population controls yielding an adjusted hazard rate ratio of 31.4 (95% CI 9.95-98.9). Cumulative incidence was 1.5% for brain abscess patients and 0.1% for population controls. DISCUSSION: HHT/PAVM should be considered in patients with cryptogenic brain abscess, although absolute risk is low.