Insights into Geographic Patterns, Urban-Rural Contrasts, and Health Care Disparities in Glomerular Disease Incidence...

Glomerular diseases (GDs) are a group of immune-mediated or genetic diseases that involve the filtering units of the kidneys, or glomeruli. Using centralized provincial kidney pathology records and census data, we aimed to examine the incidence and temporal trend of GDs in Saskatchewan, Canada and understand rural/urban differences in GD distribution.

Population-based epidemiologic study.

All adult patients who underwent kidney biopsies in Saskatchewan, Canada, from 2002-2018.

Biopsy diagnosis, 3-digit postal codes, laboratory parameters, dialysis initiation dates, and mortality data.

Incidence of primary GD, dialysis initiation, and all-cause mortality.

Regional variations in GD were analyzed using SaTScan v10.1.3 software. Incidence trends, rural/urban differences, and geospatial clustering were evaluated. Ethics approval was obtained from the provincial research and ethics board.

A total of 1,372 of 3,509 kidney biopsies met the inclusion criteria. GD incidence increased from 4.6 to 13.6 per 100,000 persons from 2002 to 2018 (P < 0.001). GD incidence was higher in rural areas than in urban areas (10.73 vs 8.92 per 100,000 per year, P < 0.001). Significantly higher dialysis progression rates were seen for rural and remote areas (P < 0.001). A geospatial cluster of 345.7 km² was identified for lupus nephropathy, with an incidence rate ratio of 1.73, a relative risk of 2.7, and a log likelihood ratio of 13.87.

Biopsies were dependent on the threshold of the ordering physician. Likely, frail and elderly patients and patients with early onset glomerulonephritis, late presentations, and higher bleeding risk were not biopsied, which led to an underrepresentation of these groups.

The incidence and relative burden of GDs have increased over time in Saskatchewan, with notable rural/urban differences. We identified a geographic cluster for lupus nephropathy encompassing rural and urban areas. Patients in rural and remote areas had higher dialysis transition rates, and mortality rates were relatively higher in urban areas. Addressing and understanding the multifaceted factors driving these disparities are essential steps toward easing the burden of GDs on impacted communities.