Clinical characteristics and predictors of in-hospital mortality in patients with ANCA-associated vasculitis complicated by diffuse alveolar hemorrhage: a retrospective cohort study.

Background: Diffuse alveolar hemorrhage (DAH) is a life-threatening manifestation of ANCA-associated vasculitis (AAV). Data regarding the determinants of in-hospital mortality, particularly the role of specific opportunistic pathogens, remain limited. Study design and methods: This retrospective cohort study included patients with AAV complicated by DAH admitted to Peking University First Hospital between January 2015 and December 2025. Clinical characteristics, bronchoalveolar lavage fluid (BALF) profiles, microbiological findings, and therapeutic interventions were compared between survivors and non-survivors. Candidate predictors were selected Results: A total of 58 patients were enrolled, of whom 13 (22.4%) died during hospitalization. Infection-related septic shock was the predominant cause of death, accounting for 76.9% of fatalities. Pulmonary infection occurred in 60.3% of the cohort and was significantly more frequent among non-survivors (92.3% vs. 51.1%; Conclusion: Among patients with AAV complicated by DAH, in-hospital mortality remains substantial and is predominantly attributable to infection-related septic shock. Higher baseline aCCI and the need for early mechanical ventilation are independent predictors of in-hospital death. The high incidence of IPA may be associated with mortality and underscores the need for heightened clinical vigilance and proactive screening in this profoundly immunocompromised population.