Epidemiology of granulomatosis with polyangiitis and microscopic polyangiitis in adults in France

Abstract

Background.Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are rare systemic necrotizing vasculitis. The national incidence and prevalence of GPA/MPA and patient mortality remain unknown in France. A real-life study using retrospective data from the French National Health Data System was set up to describe the epidemiology and demographic characteristics of hospitalized GPA and MPA patients, overall and by disease.Methods.All adult patients (≥18 years of age) hospitalized for GPA (ICD-10 M31.3) or MPA (ICD-10 M31.7) between 01 and 01–2010 and 31-12-2017 and affiliated to the General health insurance Scheme (covering 76% of the French population) were included in this national retrospective observational study. Descriptive analyses, univariate and multivariable logistic models, Kaplan-Meier survival analysis, and Cox models were performed.Results.The study involved 4445 prevalent GPA patients (including 1578 incident patients) and 1833 prevalent MPA patients (878 incident patients). Distinction between GPA and MPA diagnosis could not be made for 303 patients (149 incident patients). In people aged over 20 years, the age-standardized incidence rates of GPA and MPA were 0.5 and 0.3/100,000 person-years, respectively and the age-standardized prevalence rates were 10 and 4/100,000 person-years, respectively. The standardized mortality ratios in GPA and MPA patients aged over 20 years were 2.0 and 2.7, respectively, and remained constant. Renal failure, pulmonary and urinary tract infections, as well as coronary disease were more frequent among MPA than GPA patients. One-year survival rates among GPA and MPA patients were 96% (95%CI 94%–97%) and 94% (92%–95%), respectively. Five-year survival rates among GPA and MPA patients were 81% (95% CI 79%–83%) and 72% (68%–75%), respectively. After adjusting for comorbidities, the risk of death was still higher in MPA (hazard ratio 1.26 [95%CI 1.06–1.50]) than in GPA patients.Conclusions.Despite advances in the therapeutic management of patients, mortality rates are still high and stable over time, highlighting the need for improved management.