Mycophenolate Versus Azathioprine for Kidney Transplantation: A 15-Year Follow-Up of a Randomized Trial

The use of mycophenolate mofetil (MMF) is associated with less acute rejection than azathioprine (AZA) early after kidney transplantation. However, the long-term impact of MMF versus AZA is less well studied. The Tricontinental Mycophenolate Mofetil Renal Transplantation Study was a double-blind randomized placebo-controlled trial of MMF versus AZA, together with cyclosporine and steroids, first reported in 1996. We analyzed the long-term outcomes of the Australian cohort of patients enrolled in this study using follow-up data from the Australia and New Zealand Dialysis and Transplant Registry. Patient and graft survival, cancer incidence, and estimated kidney function were compared on an intention-to-treat basis. A total of 133 Australian patients participated in the study: 45 were randomized to AZA, 44 were randomized to MMF 2 g/d, and 44 were randomized to MMF 3 g/d. Baseline characteristics were similar between the groups. Median follow-up was 13.8 years, during which there were 97 graft failures, 75 deaths, and 1 lost to follow-up. There were no statistically significant differences between the groups in long-term patient or graft survival, cancer incidence, or kidney function. Death-censored graft survival was best in the group with 3 g/d MMF and worst in the group with 2 g/d MMF. By 5 years, 42% of the MMF group had switched permanently to AZA, whereas crossover from AZA to MMF was rare. This long-term examination, although limited by small numbers, found little evidence for the superiority of MMF over AZA.