Geographic remoteness and chronic kidney disease outcomes: a population-based cohort study using linked pathology data

Evidence on inequities in long-term chronic kidney disease (CKD) outcomes from population-based cohorts is limited, and geographic inequities across the full spectrum of CKD in Australia remain under-examined. We investigated how clinical outcomes and healthcare utilisation vary by geographic remoteness in Western Australia (WA), leveraging a state-wide linked pathology dataset spanning over 15 years. A cohort study in WA of adults (≥ 18 years) with incident CKD (2010–2017) identified from pathology data linked to hospital, emergency department (ED), and death records. CKD was defined by two estimated glomerular filtration rate (eGFR) measurements, 3–12 months apart, within the same CKD stage (3a: 45–59, 3b: 30–44, or 4: 15–29 mL/min/1.73 m²). Clinical outcomes included early CKD presentation (stage 3a), CKD progression (to a higher CKD stage or kidney failure based on eGFR), kidney replacement therapy (KRT), and all-cause mortality. Healthcare utilisation outcomes included 3-year frequency of hospital separations (completed admitted hospital stays), ED presentations, and serum creatinine testing. Associations with geographic remoteness were examined using multivariable logistic, Cox proportional hazards, and negative binomial regression, adjusting for age, sex, comorbidities, and CKD stage at cohort entry. Among 78,244 individuals (58,845 major city; 15,990 regional; 3,409 remote), remote residents had lower odds of early presentation (adjusted odds ratio aOR, 0.87; 95% confidence interval CI, 0.79–0.95) and higher hazards of progression (adjusted hazard ratio aHR, 1.15; 95% CI, 1.09–1.22), KRT (aHR, 1.94; 95% CI, 1.71–2.20), and mortality (aHR, 1.12; 95% CI, 1.06–1.19) compared with major city residents. Differences were most pronounced among those aged 18–60 years (early presentation: aOR, 0.76; 95% CI, 0.64–0.89; mortality: aHR, 1.31; 95% CI, 1.15–1.49), and 18–60 years with diabetes (progression: aHR, 1.88; 95% CI, 1.70–2.09; KRT: aHR, 2.67; 95% CI, 2.27–3.14). Healthcare utilisation was particularly elevated in the remote 18–60-year group with diabetes (ED presentations: adjusted incidence rate ratio aIRR, 3.01; 95% CI, 2.73–3.31; hospitalisations: aIRR, 2.29; 95% CI, 2.10–2.50; serum creatinine testing: aIRR, 1.16; 95% CI, 1.07–1.26). Regional residents had comparable clinical outcomes to major city residents. Population-level data from WA shows significant geographic disparities in CKD outcomes. Determining and addressing drivers of these disparities, especially among remote adults aged 18–60 years with diabetes, should be a priority for equitable kidney health policy and service planning.