Farm Exposure as a Differential Risk Factor in ANCA-Associated Vasculitis

ObjectiveTo investigate the association of farm exposure and the development of ANCA-associated vasculitis (AAV).MethodsOne hundred eighty-nine well defined patients with AAV (n = 119 with granulomatosis with polyangiitis [GPA], n = 48 with microscopic polyangiitis [MPA], n = 22 patients with eosinophilic granulomatosis with polyangiitis [EGPA]) and 190 controls (n = 119 patients with rheumatoid arthritis, n = 71 with large vessel vasculitis) were interrogated using a structured questionnaire. Factors investigated were occupation, farm exposure, contact to different livestock, participation in harvesting, residence next to a farm, MRSA status, and contact to domestic pets at disease onset or ever before. The odds ratio (OR) and 95% confidence interval [95%CI] were calculated for each item.ResultsUnivariate analysis revealed a strong association of AAV with regular farm exposure; OR 3.44 [95%CI 1.43–8.27]. AAV was also associated with regular contact to cattle 4.30 (1.43–8.27), pigs 2.75 (1.12–6.75) and MRSA carriage 3.38 (1.11–10.3). This association was stronger in the subgroup of GPA patients. OR in this group for farm exposure was 4.97; [2.02–12.2], for cattle 6.71 [95% CI 2.19–20.7], for pigs 4.34 [1.75–10.9], and MRSA carriage 5.06 [1.62–15.8]). There was no significant association of MPA or EGPA with these parameters.ConclusionA significant association between farm exposure or farm animal exposure and AAV especially in the subgroup of patients with GPA has been identified. This suggests that these entities are distinct and have different triggers for the immune process.研究目的：探讨农田暴露与抗中性粒细胞胞浆抗体相关性血管炎（ANCA-associated vasculitis, AAV）发病的关联。 研究方法：本研究纳入189例确诊AAV患者（其中119例肉芽肿性多血管炎（granulomatosis with polyangiitis, GPA）、48例显微镜下多血管炎（microscopic polyangiitis, MPA）、22例嗜酸性肉芽肿性多血管炎（eosinophilic granulomatosis with polyangiitis, EGPA））以及190例对照者（119例类风湿关节炎患者、71例大血管炎患者），采用结构化问卷开展调查。调研因素涵盖职业、农田暴露史、接触不同家畜、参与收割作业、居所毗邻农场、耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus, MRSA）定植状态，以及发病时或此前曾接触家养宠物的情况。针对每一项因素计算比值比（odds ratio, OR）与95%置信区间（95% confidence interval, 95%CI）。 研究结果：单因素分析显示，AAV与规律农田暴露存在显著关联（OR=3.44，95%CI：1.43~8.27）。AAV同时与规律接触牛（OR=4.30，95%CI：1.43~8.27）、猪（OR=2.75，95%CI：1.12~6.75）以及MRSA定植（OR=3.38，95%CI：1.11~10.3）相关。上述关联在GPA患者亚组中更为显著：该亚组内农田暴露的OR为4.97（95%CI：2.02~12.2），接触牛的OR为6.71（95%CI：2.19~20.7），接触猪的OR为4.34（95%CI：1.75~10.9），MRSA定植的OR为5.06（95%CI：1.62~15.8）。而MPA或EGPA与上述参数均无显著关联。 研究结论：本研究证实农田暴露或农场动物暴露与AAV存在显著关联，尤其在GPA患者亚组中表现突出。这提示不同AAV亚型具有异质性，其免疫致病过程的触发因素亦存在差异。