Trends in kidney transplantation in Australia and New Zealand, 1993-2004

Background. We hypothesize that transplant outcome in Australia and New Zealand has improved despite more unfavorable transplant characteristics. Data from the Australia and New Zealand Dialysis and Transplant registry was used to examine this hypothesis. Methods. All adult kidney-only transplants from January 1993 to December 2004 in Australia or New Zealand were followed-up until death or December 2005. Outcomes were adjusted for covariates in multivariate models, with transplant year modeled as a continuous variable. Results. Altogether 6764 patients were included. There were proportionately more live donor and primary transplants, older donors and recipients, and higher recipient body mass index, waiting time, and human leukocyte antigen mismatch in recent cohorts. Death-censored graft loss decreased (adjusted hazard ratio: 0.92 [0.90-0.95] per year, P < 0.001). This trend was seen at both 0-1 and 1-5 years posttransplant, and was mainly for immune-mediated graft losses. Patient survival improved only in New Zealand, and only for the first posttransplant year (adjusted odds ratio: 0.88 [0.82-0.95] per year, P = 0.001). Cardiovascular deaths decreased while infection or cancer deaths were unchanged. Adjusted delayed graft function rates were unchanged. The acute rejection incidence at 6 months decreased (adjusted odds ratio: 0.88 [0.85-0.90] per year, P < 0.001). One and 3-year graft function significantly improved, even after adjusting for rejection. All outcomes did not vary by expanded donor criteria status. Conclusions. Graft survival and function have improved in recent years, but long-term patient survival remains unchanged. With longer follow-up, the improvement in rejection rates and graft function may lead to further improvements in long-term graft survival and potentially better patient survival.