Better kidney allograft survival despite higher-risk donor and recipient characteristics between 1995 and 2014

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.

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.

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.

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.