Monica Ng

Background and hypothesis Advances in organ procurement, surgical techniques, immunosuppression regimens and prophylactic antibiotic therapies have dramatically improved short term kidney transplant graft failure. It is unclear how these interventions have affected longer term graft failure. It is hypothesised that graft failure has improved over the last 20 years. Methods Data on all first kidney transplants from 1995–2014 were extracted from the Australia and New Zealand Dialysis and Transplant Registry with follow-up as of 31 December, 2021. Primary exposure was transplant era, classified into 5-year intervals. Primary outcome was all-cause 5-year graft failure. Secondary outcomes included all-cause 10-year graft failure and cause-specific graft failure. Kaplan Meier curves and multivariable Cox Proportional Hazards Regression models were used to assess trends in all-cause graft failure. Fine-Gray subdistribution hazard models verified that changes in death rates were not biasing the Cox Proportional Hazards Regression models. Cumulative incidence functions were used to assess temporal trends in cause-specific graft failure. Results Across 10 871 kidney transplants, there was a shift towards transplanting more recipients aged over 45 years old, with more comorbidities, longer dialysis vintage, body mass index greater than 30 kg/m2 and greater human leukocyte antigen mismatches. Donor age has increased but no clear shift in donor source was observed. Compared to 1995–1999 (reference), the adjusted hazard ratio for 5-year graft failure was 0.78 (95% CI 0.67–0.91), 0.70 (95% CI 0.59–0.83) and 0.60 (95% CI 0.50–0.73) for 2000–2004, 2005–2009, and 2010–2014, respectively. Ten-year graft failure similarly reduced from 0.83 (95% CI 0.74–0.93) for 2000–04 to 0.78 (95% CI 0.68–0.89) for 2010–14, compared to 1995–99. Conclusion Medium and long term all-cause graft failure has improved steadily since 1995–99. Significant reductions in graft failure due to rejection and vascular causes were observed at 5 years, and due to rejection, vascular causes, death and glomerular disease at 10 years.