Mortality and Kidney Failure: An Epidemiological Enquiry Using Linked Health Data

Abstract

Patients with kidney failure (KF) experience high mortality and morbidity. Treatment options include kidney replacement therapy (KRT) with dialysis or kidney transplantation, or palliation. In 2018, cardiovascular disease and withdrawal from KRT were the most common causes of death in KF in Australia and New Zealand, each accounting for almost 1/3 of deaths. Effective healthcare delivery requires accurate mortality and morbidity data from clinical-quality registers. Data linkage of these registers with administrative datasets can provide insights into disease burden and optimal resource allocation. The first aim of this thesis was to describe deaths from KRT withdrawal and investigate their certified causes of death using data linkage with national administrative registers. Of 60,823 KF patients, there were 8,111 KRT withdrawal deaths. Withdrawal-related mortality doubled from 1995 to 2013, and was higher in females and older age groups. In administrative registers, kidney disease was reported as the underlying cause of death in 20% of withdrawal cases and a contributing cause in 62%, but was omitted in 18%. Reliance on administrative registers for end-of-life care planning may underestimate the true burden of KRT withdrawal. The second aim was to evaluate risk of cardiac/vascular death in KF. Cardiac/vascular deaths were identified from ICD-10-AM codes in national administrative registers. Among 60,823 KF patients, 15.6% died from cardiac/vascular causes within 15 years of KRT initiation. In the first year of dialysis, cardiac/vascular mortality peaked in the second month and showed little improvement over calendar era. Cardiovascular disease was a risk factor for composite graft failure and death post-transplant. Greater focus on prevention strategies may improve outcomes in KF, especially early on in KRT. This thesis illustrates how linked data can provide insights into mortality trends and care burden, particularly in KRT withdrawal and cardiac/vascular deaths. Additional linkage of patients managed in conservative care pathways may further guide healthcare service provision in KF.