Diffuse Alveolar Hemorrhage Secondary to Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: Predictors of Respiratory Failure and Clinical Outcomes

Objective To identify predictors of respiratory failure and to evaluate the therapeutic efficacy of plasma exchange (PE) and of rituximab versus cyclophosphamide in a cohort of patients with diffuse alveolar hemorrhage (DAH) secondary to antineutrophil cytoplasmic antibody-associated vasculitis (AAV) with or without respiratory failure. Methods We performed a single-center historical cohort study of all consecutive patients with AAV-associated DAH who were evaluated over a 16-year period. Logistic regression models were developed to examine the predictive role of the baseline clinical characteristics for the development of respiratory failure, and for the effect of PE and remission induction therapy on the main outcome (complete remission at 6 months). Results Seventy-three patients with DAH were identified, and 34 of them experienced respiratory failure. The degree of hypoxemia upon initial presentation, a higher percentage of neutrophils in the bronchoalveolar lavage fluid cell count, and higher C-reactive protein levels were independently associated with the development of respiratory failure. PE was not associated with achieving complete remission at 6 months, with an odds ratio (OR) of 0.49 (95% confidence interval [95% CI] 0.12-1.95) (P = 0.32). Rituximab treatment was independently associated with achieving complete remission at 6 months (OR 6.45 [95% CI 1.78-29], P = 0.003). Conclusion Our findings indicate that the most important predictor of respiratory failure in patients with DAH secondary to AAV is the degree of hypoxemia upon presentation. No clear benefit of the addition of PE to standard remission induction therapy was demonstrated. Complete remission by 6 months was achieved at a higher rate with rituximab than with cyclophosphamide in patients with DAH secondary to AAV, including those needing mechanical ventilation.