Who gets a kidney transplant? International differences in kidney transplant waitlisting, transplantation and mortality in the US, UK and Australia

Introduction: The purpose of this study was to compare access to and predictors of waitlisting and kidney transplantation in the United Kingdom (UK), the United States (US) and Australia (AU).
Methods: We included incident adult patients commencing kidney replacement therapy (KRT) between 2010-2020 recorded in the UK Renal Registry, Australia and New Zealand Dialysis and Transplant Registry, and US Renal Data Service. The primary outcome was kidney transplant waitlist addition with competing risks of living donor kidney transplantation (LDKT) or death. Secondary analysis included deceased donor kidney transplantation (DDKT) with competing events of LDKT or death. The cumulative incidence of the first observed outcome was recorded for each country. Multivariable competing risk Fine & Gray time-to-event models were used to compare predictors of waitlisting/LDKT.
Results: There were 24,678, 54,031 & 1,035,156 patients from AU, the UK, and the US. Baseline characteristics were similar across the three countries. Half of UK KRT patients (27,171, 50.2%) were waitlisted or received a LDKT compared to one-third of AU patients (8,874, 36.0%), and a quarter of US patients (254,961, 24.6%), Figure 1A. More KRT patients in the UK were active on the waiting list at start of KRT compared to the US and AU, Figure 1A. Waitlisting/LDKT events varied by age across the three countries and the competing risk of mortality was highest in the US. In a secondary analysis of transplant outcomes from KRT initiation, more UK patients received a LDKT or DDKT post-KRT start compared to AU and the US, Figure 1B.
In an adjusted analysis, women had a lower likelihood of waitlisting/LDKT than men across all countries (sub-distribution hazard ratios (sHR) AU 0.79 (95%CI 0.75-0.82), US 0.83 (0.83-0.84), UK 0.92 (0.9-0.94)). A socio-economic gradient was observed in all countries but was more pronounced in the US, where sHR for the likelihood of waitlisting/LDKT was lower among the most disadvantaged quintile (AU sHR0.8(95%CI 0.75-0.85), US 0.73(0.72-0.74), UK 0.78(0.75-0.81)) and higher among the least disadvantaged quintile (AU sHR1.3(95%CI 1.22-1.39), US 1.47(1.45-1.49), UK 1.26(1.21-1.3)) compared to AU and the UK. Non-metropolitan patients in Australia & the US had lower likelihood of waitlisting/LDKT. No geographical effect was observed in the UK. The effect of age, primary kidney disease, and co-morbid medical conditions on the likelihood of waitlisting/LDKT was similar across countries.  
Conclusion: Patients initiating KRT in the UK were waitlisted earlier and more frequently than those in the US or AU, and a greater proportion ultimately received a kidney transplant. Mortality occurred more often among US patients, and socioeconomic disparities in transplant access were more pronounced. These findings suggest that policies prioritising early waitlisting and timely deceased donor transplantation may substantially influence access to kidney transplantation.