Prevalence of anti-neutrophil cytoplasmic antibody-associated vasculitis in the south of France, using the capture-recapture method.

Objectives: This study aimed to estimate the prevalence of ANCA-associated vasculitis (AAV). That is, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA), in Southern France in 2018, and evaluate differences among Europeans and non-Europeans.
Methods: This population-based, cross-sectional study used four sources (hospitals, community-based physicians, laboratories, National Health Insurance) to identify adults ≥15 years diagnosed with GPA, MPA or EGPA, living in Hérault and Gard in 2018. Cases were defined using the ACR/EULAR classification criteria, and if necessary, the European Medicines Agency algorithm. Prevalence estimates were standardised to the world population and capture-recapture analysis was used to assess the comprehensiveness of the estimation. The influence of geographical origin was evaluated.
Results: A total of 202 patients were selected, with 86 cases of GPA (42.6%), 85 cases of MPA (42.1%) and 31 cases of EGPA (15.3%). The standardised prevalence estimates per million inhabitants for 2018 were: 103 (95%CI 84-125) for AAV, 48 (95%CI 35-64) for GPA, 39 (95%CI 28-53) for MPA and 16 (95%CI 9-26) for EGPA, 36 (95%CI 25-50) for anti-PR3 positive AAV, 46 (95%CI 34-61) for anti-MPO positive AAV, and 16 (95%CI 9-26) for ANCA-negative AAV. The global estimation of comprehensiveness by capture-recapture analysis was 80.5%. The number of AAV cases was higher for non-European residents (P = 0.001), particularly for MPA (P < 0.0001).
Conclusion: We provide a new estimate of AAV prevalence in France and show a higher prevalence of MPA in non-European patients.
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