SOCIO-GEOGRAPHIC DIFFERENCES IN CKD MORTALITY IN AUSTRALIA

In Australia, chronic kidney disease (CKD) incidence is increasing, contributing to 11% of deaths, and is a key factor in 18% of all hospitalisations.  Globally, social deprivation and increasing rurality are associated with a higher incidence and rate of progression of chronic kidney disease (CKD) which, in turn, is associated with increased morbidity, mortality and health resource utilisation. The impact of socio-geographical differences on CKD outcomes is important when designing healthcare delivery systems to ensure the entire population receives equal benefit from scientific progress.  This retrospective cohort study explores the impact of socioeconomic disadvantage and rurality on CKD outcomes in Australia. 

Data was prospectively collected for all patients with CKD managed by the Canberra Region Renal Services (CRRS) between 1st of November 2012 and 30th of November 2022. The CRRS covers 30,000 Km2 with a population of almost 700,000 people, spanning all deciles of the index of relative socio-economic advantage and disadvantage 2021 (IRSAD) and all rurality classes defined by the Modified Monash Model 2019 (MMM) except the level defined as very remote. Post codes were used to measure MMM classification and IRSAD decile. Patients <18 years old at inclusion and those outside the CRRS catchment area were excluded from the analysis. The aim of this analysis was to explore mortality outcome differences and their relationship to socio-geographical variables. We also assessed baseline demographics, age at referral and comorbidities including hypertension, diabetes mellitus, glomerulonephritis and genetic kidney disease.

During the study period a total of 7,152 patients with CKD stages 3a-5 were reviewed in the CRRS, of which 3,174 (44.4%) were female. The median age at registration was 69 years (IQR 58-77 years) and median follow up was 2.88 years (IQR 0.88-6.23)-years). By MMM classification, 5,070 patients (70%) lived in metropolitan areas with 5-12% of patients residing in each of categories 2-5 (regional centres to small rural towns). The majority of patients resided in the two least deprived IRSAD deciles comprising 59% of the cohort. Each decile had similar age and sex distributions with trends towards older age at inclusion in more rural locations. In the cohort 65.3% of patients had hypertension, 40.5% had diabetes, 12.6% had glomerulonephritis and 2.8% had genetic kidney disease.  There was a similar rate of comorbidities across all MMM and IRSAD strata. During the study period 2,021 patients died, the median age at death for metropolitan residents was 81 years, while in non-metropolitan areas it was 76 years (p <0.001). Those with the highest socioeconomic advantage had better survival with a median age at death of 82 years compared to 78 years in those with lesser advantage (p <0.001). 

Australians living in rural areas of the Canberra region with CKD 3a-5 and those with low socioeconomic advantage experience an up to 5-year reduction in lifespan compared to people in urban areas and those with higher socioeconomic advantage.  Future research needs to explore elements of treatment, such as medication prescribing and health resource utilisation, to further understand elements of care that may contribute to these differences in outcomes.