The association of airway comorbidities with the clinical phenotypes and outcomes of patients with antineutrophil cytoplasmic autoantibody–associated vasculitis

Objective. We investigated the association of airway comorbidities with the clinical phenotypes and outcomes of myeloperoxidase (MPO)–antineutrophil cytoplasmic antibodies (ANCA)–positive ANCA-associated vasculitis (AAV). Methods. An AAV patient multicenter cohort trial was established in 13 hospitals in western Japan between 2012 and 2018. We examined 143 of the new-onset MPO-ANCA–positive AAV patients. Their clinical characteristics and comorbidities at disease onset were compared based on clinical phenotypes. Multivariate analysis was performed to identify factors predictive of remission and death. Results. Twenty-seven cases with granulomatosis with polyangiitis (GPA), 10 with eosinophilic GPA (EGPA), 81 with microscopic polyangiitis (MPA), and 25 with unclassified AAV were identified. The average age of MPO-ANCA–positive patients was 71.4 years. Comorbidity (87.4%) and airway comorbidity (70.6%) were frequently observed in these patients. Examination of the clinical phenotypes revealed that the cases of GPA were frequently accompanied by infectious airway comorbidity (upper airway disease, bronchiectasis, pulmonary infections), and most of the cases of MPA and unclassified AAV were accompanied by fibrotic interstitial lung disease (fILD) or emphysema. Among MPO-ANCA–positive patients, infectious airway comorbidity was predictive of both remission (HR 1.58, P = 0.03) and mortality (HR 2.64, P = 0.04), and fILD was predictive of mortality (HR 7.55, P = 0.008). The combination of infectious airway comorbidities and fILD caused the worst survival outcomes in patients. Conclusion. MPO-ANCA–positive AAV was frequently accompanied by airway comorbidities. In addition to fILD, infectious airway comorbidities were closely associated with those clinical phenotypes and outcomes.