title: Does geographic location affect incidence of ANCA-associated renal vasculitis in northern Saskatchewan, Canada?
abstract: OBJECTIVE
  To compare the incidence of renal ANCA-associated vasculitis (AAV) in urban vs more rural populations in northern Saskatchewan, and as a secondary objective to compare time to diagnosis between these geographic areas.
  
  
  METHODS
  Northern Saskatchewan has a population of 562,882 of which approximately 260 600 live in the major urban area. A pathology database search for renal biopsy reports suggestive of AAV between January 2007 and December 2011 and subsequent chart review yielded 33 new diagnoses of granulomatosis polyangiitis (GPA) or microscopic polyangiitis (MPA). Data extraction included demographics, residential data, serological status, recorded symptom onset and estimations of BVAS, five-factor score (FFS) and vasculitis damage index (VDI).
  
  
  RESULTS
  Of 33 renal AAV cases, 24.2 % (n = 8) lived within the city. The incidence rate for urban residents was 6.1 cases/million/year, and for those residing elsewhere, 16.5 cases/million/year. The odds ratio for the more rural population was 2.69 (95% CI 1.3, 7.5). Mean time to diagnosis was 1.33 (s.d. 0.94) months for urban and 3.52 (s.d. 3.83) months for more rural patients (P = 0.002, 95% CI 0.7, 3.9). Secondary analysis supported these observations with higher BVAS, VDI and FFS scores in patients living outside the urban centre.
  
  
  CONCLUSIONS
  The incidence of renal biopsy-proven AAV was higher in patients living in northern Saskatchewan smaller communities and rural settings. A significantly longer time to diagnosis existed for patients outside the urban centre and was associated with poorer BVAS, VDI and FFS scores.
authors.affiliation: Division of Rheumatology, Department of Medicine, University of Saskatchewan, Royal University Hospital, Saskatoon, Saskatchewan, Canada S7N 0W8. r.gjevre@usask.ca.
authors.forename: Keltie
authors.initials: K
authors.lastname: Anderson
authors.forename: Judy
authors.initials: J
authors.lastname: Klassen
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Stewart
authors.forename: Regina M
authors.initials: RM
authors.lastname: Taylor-Gjevre
mesh_terms: D000367:Age Factors; D000368:Aged; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007674:Kidney Diseases / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012423:Rural Health / Q000706:statistics & numerical data*; D012525:Saskatchewan / Q000453:epidemiology; D012737:Sex Factors; D013997:Time Factors; D014504:Urban Health / Q000706:statistics & numerical data*
keywords: ANCA; diagnosis; granulomatosis with polyangiitis; microscopic polyangiitis; rural; urban