Better Kidney Allograft Survival Despite Higher-risk Donor and Recipient Characteristics Between 1995 and 2014

Background And Hypothesis: Advances in organ procurement, surgical techniques, immunosuppression regimens, and prophylactic antibiotic therapies have dramatically improved kidney transplant graft failure. It is unclear how these interventions have affected longer-term graft failure. It is hypothesized that graft failure has improved over the last 20 years.

Methods: Data on all first kidney transplants from 1995 to 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 >45 years old, with more comorbidities, longer dialysis vintage, body mass index >30 kg/m2, and greater human leukocyte antigen mismatches. Donor age has increased but no clear shift in donor source was observed. Compared to 1995-99 (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 2000-04, 2005-09, and 2010-14, 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.