Does geographic location affect incidence of ANCA-associated renal vasculitis in northern Saskatchewan, Canada?

Keltie Anderson, Judy Klassen, Samuel A. Stewart, Regina M. Taylor-Gjevre
2013 Rheumatology  
Objectives. 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
more » ... ew 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. Conclusion. 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.
doi:10.1093/rheumatology/ket226 pmid:23838025 fatcat:bx7okfnb2vgapllkompt7zjacu