Tacrolimus therapeutic drug monitoring and pediatric renal transplant graft outcomes

Predose monitoring of tacrolimus levels is standard practice in the care of pediatric renal transplant patients. This is despite a paucity of data investigating the ideal target range in children, and controversy as to whether tacrolimus levels correlate with renal transplant outcomes. We performed a retrospective cohort analysis of 48 renal transplant patients at a single Canadian pediatric transplant center following the initiation of a tacrolimus-mycophenolate-prednisone-based IS protocol. We analyzed the relationship of graft function, as defined by GFR up to fiveyr post-transplant, to the preceding mean tacrolimus level. There was no significant correlation between absolute GFR and mean tacrolimus levels (r=0.206, p=0.38). However, a higher mean tacrolimus level, particularly 10ng/mL in the first threemonths after transplantation, was associated with a slower rate of decline in GFR with time (r=0.608, p=0.004) and with a less likelihood of developing CKD fiveyr after transplant. We suggest that the optimal target range for tacrolimus levels may be at the upper end of what is currently practiced and that further research to validate these findings would be useful.