Mortality in Behçet's Syndrome in a non-endemic population: a 25-year cohort study.

Mortality in Behçet's syndrome (BS) has been consistently associated with neurological and vascular involvement in studies from endemic regions. However, data from non-endemic countries remain limited. This study aimed to evaluate long-term mortality and identify factors associated with mortality in a large Brazilian cohort of patients with BS. We conducted a retrospective cohort study including 303 adult patients diagnosed with BS and followed at a tertiary referral center in São Paulo, Brazil, between January 2000 and December 2024. Demographic, clinical, comorbidity, and treatment data were collected. Mortality rates were assessed, and factors associated with mortality were analyzed using unadjusted Cox proportional hazards models, with hazard ratios (HRs) and 95% confidence intervals (CIs). Among the 303 patients included, 61.6% were female, with a median follow-up of 117 months (IQR 55-184). A total of 162 patients (53.4%) were lost to follow-up. Eight deaths (2.6%) occurred during the study period. Given the limited number of events, only exploratory, unadjusted analyses were performed. Pulmonary artery aneurysm (HR 28.44, 95% CI 3.32-243.52; p = 0.002), central nervous system (CNS) parenchymal involvement (HR 6.81, 95% CI 1.65-28.06; p = 0.008), diabetes mellitus (HR 6.72, 95% CI 1.67-27.03; p = 0.007), and malignancy (HR 8.81, 95% CI 2.02-38.50; p = 0.004) were associated with increased mortality. Our exploratory analyses suggest that vascular and neurological involvement, particularly pulmonary artery aneurysm and CNS parenchymal disease, may be associated with increased mortality in our population.