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Objective: Silica is an environmental substance strongly linked with autoimmunity. The aim of this study was to assess the prevalence of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and renal limited vasculitis, in a northeastern region of France and to evaluate whether there was a geospatial association between the localization of quarries in the region and the prevalence of these AAVs., Methods: Potential AAV patients were identified using 3 sources: hospital records, immunology laboratories, and the French National Health Insurance System. Patients who resided in the Alsace region of France as of January 1, 2016 and who fulfilled the American College of Rheumatology criteria for GPA or the 2012 Chapel Hill Consensus Conference definitions for GPA or MPA were included. Incomplete case ascertainment was corrected using a capture-recapture analysis. The spatial association between the number of cases and the presence of quarries in each administrative entity was assessed using regression analyses weighted for geographic region., Results: Among 910 potential AAV patients, we identified 185 patients fulfilling inclusion criteria: 120 patients with GPA, 35 patients with MPA, and 30 patients with renal limited vasculitis. The number of cases missed by any source as estimated by capture-recapture analysis was 6.4 (95% confidence interval [95% CI] 3.6-11.5). Accordingly, the estimated prevalence in Alsace in 2016 was 65.5 GPA cases per million inhabitants (95% CI 47.3-93.0), 19.1 MPA cases per million inhabitants (95% CI 11.3-34.3), and 16.8 renal limited vasculitis cases per million inhabitants (95% CI 8.7-35.2). The risk of AAV was significantly increased in communities with quarries (odds ratio 2.51 [95% CI 1.66-3.80]), and geographic-weighted regression analyses revealed a significant spatial association between the proximity to quarries and the number of GPA cases (P = 0.039). In analyses stratifying the AAV patients by ANCA serotype, a significant association between the presence of quarries and positivity for both proteinase 3 ANCAs (P = 0.04) and myeloperoxidase ANCAs (P = 0.03) was observed., Conclusion: In a region with a high density of quarries, the spatial association between the presence of and proximity to quarries and the prevalence of AAVs supports the idea that silica may have a role as a specific environmental factor in this disease., (© 2021, American College of Rheumatology.)

Objective: Alsace is a region in eastern France with a population of ∼2 million. All residents have high access to health care and an accredited referral center for SSc. Seeking care outside of this region is difficult because of the peculiar geography. The aim of this study was to assess the prevalence and spatial variation of systemic sclerosis (SSc) in eastern France., Methods: Data for SSc patients were obtained from 3 sources (all general practitioners and community specialists, capillaroscopy centers, and all public and private hospital records) and were used to estimate the prevalence of SSc. Surviving patients who resided in Alsace on January 1, 2008 and fulfilled the American College of Rheumatology and/or the LeRoy and Medsger criteria were included in this study. The clinical characteristics of the patients were also assessed. Potentially incomplete case ascertainment was corrected by capture-recapture analyses. Geographic disparities were assessed by spatial cluster analysis and by comparing our results with those for other geographic areas in the world for which data derived using similar methodology were available., Results: The review of 499 potential cases identified a total of 244 SSc patients. A trend toward a west-to-east gradient was observed but did not reach statistical significance. According to log-linear modeling, an estimated 83.87 additional cases were missed. Thus, the SSc prevalence was 228.42 cases per million adult inhabitants of Alsace (95% confidence interval 203.70-253.14); this prevalence was significantly higher than that in 2 other regions of France and comparable with the reported prevalence in Detroit, Michigan., Conclusion: The stringent methodology used in the current study is very likely to provide an accurate estimation of the prevalence of SSc. Design similarity with 3 other surveys extends the scope of the results by identifying geographic disparities that were previously indistinguishable due to methodologic differences., (© 2016, American College of Rheumatology.)