Island medicine: using data linkage to establish the kidney health of the population of Tasmania, Australia.

Objective: To report (using linked laboratory data) the incidence, prevalence and geographic variation of chronic kidney disease (CKD) across the whole island population of Tasmania, Australia.

Methods: A retrospective cohort study (the Tasmanian Chronic Kidney Disease study (CKD.TASlink)) using linked data from five health and two pathology datasets from the island state of Tasmania, Australia between 1/1/2004 and 31/12/2017. We used data on 460,737 Tasmanian adults (aged 18 years and older, representing 86.8% of the state's population) who had a serum creatinine measured during the study period. We defined CKD as per Kidney Disease Outcomes Quality Initiative, requiring two measures of estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m, at least three months apart. Kidney replacement therapy (KRT) included dialysis or kidney transplantation.

Results: We identified 56,438 Tasmanians with CKD during the study period, equating to an age-standardised annual incidence of 1.0% and a prevalence of 6.5%. These figures were higher in women, older Tasmanians and people living in the North-West region of Tasmania. Testing for urinary albumin:creatinine ratio is increasing, with 28.5% of women and 30.8% of men with stage 3 CKD having both an eGFR and uACR in 2017. Use of KRT was consistently seen in >65% of Tasmanians with eGFR <15 mL/min/1.73m.

Conclusion: There is geographic and gender variation in the incidence and prevalence of CKD, but it is reassuring to see that the majority of people with end-stage kidney failure are actually receiving treatment with dialysis or transplantation.