Incidence of poststreptococcal glomerulonephritis in northwestern Ontario: Cross-sectional study at a tertiary care centre.

Abstract

To measure the incidence of poststreptococcal glomerulonephritis (PSGN) and resulting complications in northwestern Ontario, including among Indigenous and rural populations. Cross-sectional study. As the only tertiary care hospital in northwestern Ontario, Thunder Bay Regional Health Sciences Centre (TBRHSC) functions as the primary referral centre for most of the region. The catchment population has substantial Indigenous (21.5%) and rural (34.2%) populations. All cases of PSGN managed at TBRHSC over an 8-year period from January 1, 2010, to December 31, 2017. Cases were classified as confirmed, probable, or possible based on the type of evidence available. Patients' rurality and Indigenous status were recorded. Incidence rates and incidence rate ratios of all, pediatric (<18 years), and adult PSGN cases were calculated, as were incidence rates and incidence rate ratios of those requiring dialysis. Linear interpolation and extrapolation were used to estimate the population in non-census years. Over the 8-year study period, 33 cases of PSGN were observed with annual incidence rates of 0.0 to 4.8 per 100,000 person-years and a mean annual incidence rate of 1.8 (95% CI 1.2 to 2.5) per 100,000 person-years. Of these 33 cases, 28 were confirmed with renal biopsy or clinical and laboratory data. Indigenous patients accounted for 61% (n=17) of confirmed cases and were 6.0 (95% CI 2.8 to 13, P<.001) times as likely to have PSGN and 9.6 (95% CI 3.0 to 31, P<.001) times as likely to require dialysis compared with non-Indigenous patients. Patients living in rural areas accounted for 71% (n=20) of confirmed cases and were 3.2 (95% CI 1.4 to 7.3, P=.006) times as likely to have PSGN and 3.9 (95% CI 1.0 to 10, P=.02) times as likely to require dialysis compared with patients in urban areas. The main burden of PSGN in northwestern Ontario occurs among Indigenous and rural populations. Additional research is required to investigate the true overall burden of PSGN in the region. In collaboration with regional Indigenous groups, advocacy is needed for PSGN to be made reportable and public health action must be taken to address these pronounced disparities.