Comparison of azathioprine with mycophenolate mofetil in a living donor kidney transplant programme

There are conflicting data regarding the comparative efficacy of mycophenolate mofetil (MMF) versus azathioprine (AZA) as maintenance immunosuppressive agent in kidney transplantation. The data are even less in combination with tacrolimus (TAC) in living donor kidney transplantation. A total of 205 living donor kidney transplants, on TAC-based triple drug immunosuppression were included in the study. A total of 113 patients received AZA and rest 92 were on MMF based protocol. TAC levels were monitored and graft biopsy was done whenever rejection was suspected. The outcomes were evaluated in terms acute rejection (AR) episodes at 1 year, infections, renal function, graft loss, and death between two groups. The study group comprised 163 males (79.5%) and 42 (20.5%) females. The mean age of patients was 42.4±11.8 years in the AZA group and 39.4 ±13.4 in the MMF group (P=0.09). The mean duration of follow-up was 491.7±240.7 and 478.8±334.4 days respectively in the AZA and MMF groups (P=0.75). Thirty-seven of 92 (40.2%) patients in the MMF group and 70/113 (61.9%) patients in the AZA group received IL-2 RAb induction (P=0.002). 32 patients (15.6 %) developed AR within a year. The incidence of AR was similar in patients who received MMF (12/92, 13%) and those who received AZA (20/113, 17.5%), (P=0.36). There was no difference in the incidence of AR in the subgroup of patients who received IL-2 RAb compared to those who did not receive induction in the two groups (5/37 vs. 7/55 in the MMF group and 10/70 vs. 10/43 in the AZA group, P=0.72). The incidence of infections was similar in the two groups (19/92, 20.6% vs. 25/113, 22.1%, P=0.79). Three patients developed CMV disease, of which two were in the MMF group. Graft loss occurred in 7/205 (3.4%) and death in 8/205 (3.9%) patients. Six of eight patients who died had functioning grafts. The rate of graft loss (3/92 vs. 4/113, P=0.97) and death (5/92 vs. 3/113, P=0.27) was similar in two groups. The overall patient survival was 94.5% and death censored graft survival was 97.4%. Cost comparison suggests AZA to be 6-10 times cheaper than MMF. This study suggests that, in tacrolimus-based immunosuppression, azathioprine may be as good as MMF as maintenance immunosuppressive drug in living donor kidney transplantation. It is also a more cost-effective immunosuppression.