Kidney Week

Abstract: SA-PO637

Proximity of Residence to Silica Mines as a Risk Factor for Anti-Neutrophil Cytoplasmic Antibody-Associated (ANCA) Vasculitis

Session Information

• Glomerular Diseases: ANCA, Anti-GBM, Kidney Biopsy
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

• Hepburn, Kirsten S., Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia

Kirsten S. Hepburn,

• Pastore, Gianna, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia

Gianna Pastore,

• Jegatheesan, Dev Krish, Princess Alexandra Hospital, Brisbane, Queensland, Australia

Dev Krish Jegatheesan,

• Ranganathan, Dwarakanathan, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia

Dwarakanathan Ranganathan,

Background

Anti-neutrophil cytoplasmic antibody-associated (ANCA) vasculitis is a rare necrotizing vasculitis affecting small to medium-sized vessels, with renal involvement usually presenting with a rapidly progressive glomerulonephritis. There is evidence to suggest that silica exposure is associated with the development of ANCA vasculitis. The incidence of ANCA vasculitis in Queensland, Australia was 0.47 per 100,000 people/year from 2002 to 2011; and there is a high density of silica mines, with approximately 2 per 1,000,000 population in 2011. The aim of the study was to examine whether residing close to silica mines is associated with development of ANCA vasculitis.

Methods

This retrospective cohort study compared patients with a biopsy-proven diagnosis of ANCA vasculitis and a control cohort of IgA nephropathy (IgAN) from 2009 to 2011. IgAN was selected as there is no known association between silica exposure and its development. A pathology database of renal biopsies was used to identify cases of ANCA vasculitis and IgAN. Age, gender, postcode and suburb of the patient at the time of biopsy were obtained. The distance between the suburb and closest silica mine in Queensland was calculated using Quantum GIS 3.4 software. Distance to silica mines was categorised into ≤50km, 51-99km and ≥ 100km. SPSS was used, with a X² test for independence to determine association between distance to silica mines and ANCA vasculitis.

Results

135 patients were identified, with a mean age of 48 years and 60% were male. There were 44 cases of ANCA vasculitis and 91 cases of IgAN. Patients diagnosed with ANCA vasculitis were significantly older (63.5 years v 40.9 years, p<0.05). 50% of ANCA vasculitis patients resided within 50km of a silica mine, compared to 44% of patients with IgAN. 20.5% and 29.5% of ANCA vasculitis patients resided 51-99km and ≥ 100km respectively; compared to 22% and 34.1% of patients with IgAN respectively. There was no evidence of association between distance from suburb to silica mine and ANCA vasculitis (X²_(2,135)=0.45, p=0.8).

Conclusion

There was no evidence that proximity of residence to silica mines was associated with ANCA vasculitis compared to IgAN in this cohort of patients. Limitations include small sample size and inability to account for patient relocation prior to biopsy.