Seasonal influence on development of anti-neutrophil cytoplasmic antibody-associated vasculitis: a retrospective cohort study conducted at multiple institutions in Japan (J-CANVAS).

Abstract

To clarify seasonal and other environmental effects on the onset of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We enrolled patients with new-onset eosinophilic granulomatosis with polyangiitis (EGPA), microscopic polyangiitis (MPA), and granulomatosis with polyangiitis (GPA) registered in the database of a Japanese multicenter cohort study. We investigated the relationship between environmental factors and clinical characteristics. Seasons were divided into four (spring, summer, autumn, and winter), and the seasonal differences in AAV onset were analyzed using Pearson's chi-squared test, with an expected probability of 25% for each season. A total of 454 patients were enrolled, with a mean age of 70.9 years and a female proportion of 55.5%. Overall, 74, 291, and 89 patients were classified as EGPA, MPA, and GPA, respectively. Positivity for myeloperoxidase (MPO)-ANCA and proteinase 3 (PR3)-ANCA was observed in 355 and 46 patients, respectively. Overall, the seasonality of AAV onset significantly deviated from the expected 25% for each season (p=0.001), and its onset was less frequently observed in autumn. In ANCA serotypes, seasonality was significant in patients with MPOANCA (p<0.001), but not in those with PR3-ANCA (p=0.97). Additionally, rural residency of patients with AAV was associated with PR3-ANCA positivity and biopsy-proven pulmonary vasculitis. The onset of AAV was influenced by seasonal variations and was less frequently observed in autumn. In contrast, the occurrence of PR3-ANCA was not triggered by season, but by rural residency.