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

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.

Evolution of therapeutic management of patients with ANCA associated vasculitis in France after licensing Rituximab use.

INTRODUCTION: In 2013, rituximab was approved in France for the treatment of ANCA-associated vasculitis (AAV). The aim of the study was to compare the treatment and health events of adult incident patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), included before rituximab approval (over 2010-2012, Group 1) and those included after rituximab approval (over 2014-2017, Group 2). METHOD: Data were extracted from the French National Health Insurance database (SNDS) including outpatient health care consumption and hospital discharge forms. Comparisons between inclusion periods were performed using Wilcoxon and χ² tests. Kaplan-Meier method was used to model the duration of treatment induction, maintenance, and off-drug periods. Fine and Gray tests were used to compare treatment phase durations. RESULTS: A total of 694 GPA and 283 MPA patients were included in Group 1, while 668 GPA and 463 MPA patients were included in Group 2. Between the two inclusion periods, the proportions of patients treated with rituximab increased in the induction and maintenance phases whereas treatment with azathioprine declined. These proportions remained stable in the case of methotrexate, cyclophosphamide, and glucocorticoid-treated patients. Frequency of first-time hospitalized infections, diabetes and renal failure during the first year after inclusion increased for both groups. LIMITATIONS OF THE STUDY: This is a retrospective study based on claims data including only 76% of people covered by health insurance in France. The period studied includes the learning phase of using rituximab. This study lacks biological data and precise quantitative analysis for the use of steroids, therefore the criteria for establishing diagnosis and therapeutic choice were unknown. CONCLUSIONS: Introduction of rituximab reduced the use of azathioprine without affecting the use of glucocorticoids or cyclophosphamide.