Flow diagram of screening for participants in this study.

<p>The crude number of patients with microscopic polyangiitis was counted on the basis of ICD-10 codes from medical records in our hospital. Each of the patients was diagnosed with MPA based on the CHCC2012 criteria. Drug-induced and recurrent cases were excluded. Abbreviations: ICD, international classification of diseases; RPGN, rapidly progressive glomerulonephritis; GPA, granulomatosis with polyangiitis; EGPA, eosinophilic granulomatosis with polyangiitis, CHCC; Chapel Hill Consensus Conference, MPA; microscopic polyangiitis.