V KHELGI1, 2, A GUPTA1, 2, S VENUTHURAPALLI1 2, A LEE1, S GOVINDARAJULU1, 2
1Renal service, Darling Downs Hospital and Health Service, Toowoomba, Queensland; 2Rural School of Medicine, University of Queensland Toowoomba, Queensland
Aim: Audit of prevalence of ANCA vasculitis and its association with farm exposure and seasonal variation.
Background: DDHHS caters to a geographic area of 90,000 sq km with a population of over 300,000 of which 40% belong to farming community. Genetic and environmental factors like silica exposure have been associated in the pathogenesis of AAV apart from the traditional immune factors. An audit was undertaken to investigate the prevalence of AAV in our farming community with seasonal variation as a additional associating factor.
Methods: We undertook a retrospective analysis of kidney biopsies performed at DDHHS over a 10-year period from 2006 to 2016. Biopsy proven AAV patients were identified and history of farm exposure was enquired through a structured questionnaire via telephone interview. The seasonal association was noted through the month at the time of the biopsy.
Results: Of 216 biopsies performed at DDHHS twenty-nine (n=29) were diagnosed as AAV. The mean age of patients was 66.4 years (16-86) with higher prevalence of the disease in females than males (Females 18, Males 11) and a higher prevalence of Myeloperoxidase AAV (MPO n=19) compared to proteinase 3 AAV(PR3 n=9). One case was drug induced AAV with double positivity for MPO and PR3. 16 AAV were diagnosed in spring, 6 in summer, 4 in autumn and 3 in winter months. 16 out of 29 patients (55%) had direct exposure to farm, harvesting, fertilizers and farm animals
Conclusions: Our audit revealed a significant association between farm exposure and development of AAV. An increased prevalence of MPO AAV in spring months in patients with farm exposure was noted. Further studies are warranted to determine the pathogenesis underlying this association.