Pulmonary Fibrosis in Antineutrophil Cytoplasmic Antibodies (ANCA)-Associated Vasculitis

Pulmonary fibrosis (PF) is an uncommon manifestation observed in patients with antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), particularly microscopic polyangiitis (MPA). While patients with PF associated with AAV seem to have a worse prognosis, these patients have been described only in case reports or small retrospective case series. In this retrospective multicenter study, we report the main features and long-term outcomes of patients with PF associated with AAV, fulfilling the American College of Rheumatology criteria and/or Chapel Hill definitions. Forty-nine patients (30 men [61%]; median age at diagnosis of AAV, 68 [interquartile range, 58-73] years) with PF associated with AAV were identified. Forty (81.6%) patients had MPA and 9 (18.4%) had granulomatosis with polyangiitis. The diagnosis of PF preceded the onset of vasculitis in 22 (45%) patients. Usual interstitial pneumonia was the main radiologic pattern (n = 18, 43%). ANCA were mostly of antimyeloperoxidase specificity (88%). All patients were treated with glucocorticoids as induction therapy, combined with cyclophosphamide (CYC) (n = 36, 73.5%) or rituximab (RTX) (n = 1, 2%). Factors associated with mortality included occurrence of chronic respiratory insufficiency (hazard ratio [HR], 7.44; 95% confidence interval [CI], 1.6-34.5; p = 0.003), induction therapy with glucocorticoids alone (HR, 2.94; CI, 1.05-8.33; p = 0.04), and initial weigh loss (HR, 2.83; CI, 1.05-7.65; p = 0.041). The 3-year survival rate in patients treated with glucocorticoids alone or combined with an immunosuppressant (CYC or RTX) as induction therapy was 64% (95% CI, 41-99) and 94% (95% CI, 86-100), respectively (p = 0.03). After a median follow-up of 48 months [interquartile range, 14-88 mo], 18 (37%) patients died, including 11 related to respiratory insufficiency. PF is a rare manifestation of AAV with a very poor prognosis. Induction therapy with CYC might improve the outcome.