Retrospective study on the epidemiology of antineutrophil cytoplasmic autoantibodies‐associated vasculitis in two Australian health districts

Abstract

Background Antineutrophil cytoplasmic autoantibodies (ANCA)‐associated vasculitis (AAV) is more prevalent in rural Australia compared with metropolitan areas, suggesting a role of environment in disease pathogenesis. However, the prevalence of environmental risk factors in Australian AAV patients has not been described. Aims To compare the incidence of AAV between two health districts (Illawarra Shoalhaven Local Health District (ISLHD), a mixed rural/metropolitan region, and South Eastern Sydney Local Health District (SESLHD), a metropolitan region) in Australia and its relationship to environmental exposures. Methods Cases of AAV from 2002 to 2017 were retrospectively identified from ISLHD and SESLHD using electronic medical records. Eligible participants were invited to complete a standardised questionnaire examining their exposure to silica, solvents, metal, dust, farming, gardening and sunlight. Results One hundred and fifty‐six cases of AAV were identified from 2002 to 2017. A higher cumulative incidence of AAV was observed in the ISLHD (184.2 (95% confidence interval (CI) 143.6–232.7) per million) compared with SESLHD (102.6 (95% CI 82.1–126.8) per million). Over 50% of the cohort had high levels of silica and solvents exposure, based on self‐reported questionnaires. There was no significant relationship between region and exposure to silica (P = 0.96), solvents (P = 0.44), metal (P = 0.33), dust (P = 0.25), farming (P = 0.90), gardening (P = 0.93) or sunlight (P = 0.55). Conclusions We found a higher incidence of AAV in ISLHD compared with SESLHD with high levels of exposure to silica and solvents in both regions based on self‐reported questionnaires. Prospective systematic collection of data, such as a registry of AAV, is warranted to further explore the relationship between environmental exposures and AAV.

Incidence of anti‐neutrophil cytoplasmic antibody‐associated renal vasculitis: a retrospective study in rural and regional Victoria, Australia

“…This study does not clearly suggest that rural and regional Victoria have a greater incidence of AAV than urban Australian areas. Our overall disease incidence was higher than that described in central Sydney (6 per million/year, 95% CI: 1.9–13.9) 5 ; however, it was lower than that reported in Melbourne between 2009 and 2011 (22 per million/year) 9 . Our estimate was similar to the incidence in urban WA (10.1 per million/year, 95% CI: 7.6–13.8) 8 and the ACT (10.5 per million/year) 6 .…”

“…In Australia, a higher incidence of AAV has been reported in rural compared to urban areas. 5,6 Similar findings have also been described internationally in Scotland 10 and Canada. 11 Increased environmental exposure to farming and agents such as silica has been postulated as an explanation for a relationship between rurality and AAV.…”

“…In Australia, a higher incidence of AAV has been reported in rural compared to urban areas 5,6 . Similar findings have also been described internationally in Scotland 10 and Canada 11 .…”

“…3 Local epidemiological data are valuable for AAV as the disease incidence varies worldwide. 4 Prior Australian studies described the incidence of AAV in New South Wales (NSW), 5,6 South Australia (SA), 7 the Australian Capital Territory (ACT) 6 and Western Australia (WA). 8 These articles report an overall incidence of AAV ranging from 6 to 17 cases per million/year.…”

Environmental factors influencing the risk of ANCA-associated vasculitis

“…Studies in Scotland, Germany, and Canada showed that the incidence of AAV in rural areas is higher than that in cities. This may be related to environmental pollutants and pesticide exposure in remote areas (68,72,78,79). Additionally, a large Swedish case-control study (73) found no association between occupation and GPA (Table 1).…”