Incidence, Prevalence, and Mortality of Eosinophilic Granulomatosis With Polyangiitis in Korea: A Nationwide Population-Based Study.

Purpose: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of vasculitis with multiorgan involvement. The incidence and prevalence of EGPA vary geographically and ethnically. This study investigated the incidence, prevalence, and mortality of EGPA in a nationwide population-based cohort in Korea.

Methods: This retrospective cohort study used data from the National Health Insurance database that covers almost all Korean residents. EGPA was identified using relevant diagnostic codes from 2007 to 2018. Newly diagnosed EGPA cases since 2007 and patients who visited outpatient clinics for EGPA at least three times were included. Age- and sex-adjusted standardized incidence and prevalence rates were analyzed.

Results: A total of 843 patients with EGPA were identified. The mean annual standardized incidence between 2007 and 2018 was 1.2 (per 1,000,000 individuals). The incidence of EGPA has increased from 1.1 (per 1,000,000 individuals) in 2007 to 1.6 (per 1,000,000 individuals) in 2017. The standardized prevalence of EGPA has increased from 1.1(per 1,000,000 individuals) in 2007 to 11.2 (per 1,000,000 individuals) in 2018. The incidence and prevalence of EGPA were higher in women than in men. The standardized mortality rate was 1.61 (95% confidence interval [CI], 1.34-1.93) in total population, 1.59 (95% CI, 1.23-2.02) in males, and 1.63 (95% CI, 1.22-2.13) in females.

Conclusions: The incidence of EGPA has increased over the past decade. Incidence and prevalence rates were higher in females than in males. The overall mortality rate associated with EGPA was higher than that in the general population.