Antineutrophil cytoplasmic antibody-associated vasculitis in Taiwan: A hospital-based study with reference to the population-based National Health Insurance database

BackgroundAntineutrophil cytoplasmic antibody-associated vasculitis (AAV), including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and Churg–Strauss syndrome (CSS), comprises a group of diseases with significant morbidity and mortality. The incidence and relative frequency of GPA/MPA/CSS are different all over the world. The epidemiology of AAV in Taiwan is still not clear.MethodsThe current study aimed to provide a population-based estimate of the annual incidence of GPA using the Taiwan National Health Insurance (NHI) research database and a single hospital-based estimate of the relative frequency of AAV in Taiwan.ResultsThe annual incidence of GPA in Taiwan was 0.37 per million patient-years (95% Poisson rate confidence interval: 0.30–0.45) from 1997 to 2008, according to the NHI database. In our hospital, 24 patients were newly diagnosed with AAV between 2003 and 2011, including eight patients with GPA, 14 with MPA, and two with CSS. The ratio of the number of patients with GPA to that of MPA was 0.57.ConclusionThe current results provide an estimate of the annual incidence of GPA and the relative frequency of AAV in the Chinese Han community in Taiwan. Such geoepidemiology information may help illuminate the interaction between ethnic background and environment in these autoimmune diseases.