Chronic Kidney Disease in Tasmania: Protocol for a Data Linkage Study

Abstract

Background Chronic kidney disease (CKD) is a significant and growing health burden globally. Tasmania has the highest state prevalence for non-Indigenous Australians and it has consistently had the lowest incidence and prevalence of dialysis in Australia. Objective To examine the gap between the high community prevalence of CKD in Tasmania and the low use of dialysis. Methods This is a retrospective cohort study using linked data from 5 health and 2 pathology data sets from the island state of Tasmania, Australia. The study population consists of any person (all ages including children) who had a blood measurement of creatinine with the included pathology providers between January 1, 2004, and December 31, 2017. This study population (N=460,737) includes within it a CKD cohort, which was detected via pathology or documentation of kidney replacement therapy (KRT; dialysis or kidney transplant). Kidney function (estimated glomerular filtration rate [eGFR]) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. Individuals with 2 measures of eGFR<60 mL/min/1.73 m2, at least 90 days apart, were identified as having CKD and were included in the CKD cohort. Individuals treated with dialysis or transplant were identified from the Australia and New Zealand Dialysis and Transplant Registry. Results The study population consisted of 460,737 people (n=245,573 [53.30%] female, mean age 47.4 years) who were Tasmanian residents aged 18 years and older and were followed for a median of 7.8 years. During the later 5 years of the study period, 86.79% (355,622/409,729) of Tasmanian adults were represented. The CKD cohort consisted of 56,438 people (ie, 12.25% of the study population; 53.87% (30,405/56,438) female, mean age 69.9 years) followed for a median of 10.4 years with 56,039 detected via eGFR and 399 people detected via documentation of KRT. Approximately half (227,433/460,737, 49.36%) of the study population and the majority of the CKD cohort (41,448/56,438, 73.44%) had an admission episode. Of the 55,366 deaths recorded in the study population, 45.10% (24,970/55,366) had CKD. Conclusions Whole-of-population approaches to examine CKD in the community can be achieved by data linkage. Over this 14-year period, CKD affected 12.25% (56,438/460,737) of Tasmanian adult residents and was present in 45.10% (24,970/55,366) of deaths. International Registered Report Identifier (IRRID) DERR1-10.2196/20160

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

“…During the 14-year study period, 460,737 Tasmanian adults had a serum creatinine measured. The CKD Cohort was detected as 56,438 which consisted of those detected by pathology met the international definition of CKD (56,039) or presence on the ANZDATA registry (399) [ 10 ]. There were 1051 individuals treated with KRT over the 14-year period, many subsequent to diagnosis.…”

“…The Tasmanian Chronic Kidney Disease study (CKD.TASlink) was a retrospective cohort study that examined a dataset created by linkage of seven existing local health information datasets. Detailed methods and linked data obtained are available elsewhere [ 10 ]. Briefly, pathology data on 490,012 individuals (from birth) was obtained from community and hospital-based pathology providers between 1/1/2004 to 31/12/2017.…”

“…The estimated Tasmanian resident population (ERP) in 2017 was 522,410 of which 409,729 were aged 18 years and older [ 8 ]. Individuals identified within the dataset comprised 47.6% of the overall adult Tasmanian population when studied over one year, 74.2% over three years and 86.8% over five years in the period 2013 to 2017 [ 10 ]. As this is a pathology dataset based on serum creatinine, annual representation varied with age: for instance, in 2017, 82.5% of Tasmanian 80 to 84-year-olds were represented, but only 7.8% of people under 18 years.…”

“…To understand the relationship between kidney health and disease in the community and access to KRT in specific locations across the island state, we established a linked dataset containing both community and hospital data [ 10 ]. The aim of this present study was to confirm the state incidence and prevalence of CKD and use of KRT in Tasmania.…”

Competing risks of death and kidney failure in a cohort of Australian adults with severe chronic kidney disease

“…The Tasmanian Chronic Kidney Disease study (CKD.TASlink) was a retrospective cohort study that analysed a dataset compiled by linking seven local health information datasets. The methodology has been reported in detail elsewhere 6 . Briefly, pathology data for 490 012 people during the period 1 January 2004 – 31 December 2017 were obtained from four community and hospital‐based pathology providers (Hobart Pathology, Launceston Pathology, North West Pathology, Royal Hobart Hospital Pathology; two smaller pathology providers were not included).…”