Is acute rejection the key predictor for long-term outcomes after renal transplantation when comparing calcineurin inhibitors?

In the context of modern immunosuppressive regimens, the overall incidence of acute rejection may no longer be the most accurate surrogate marker for long-term kidney graft survival. The type, severity, timing, and clinical course of acute rejection each influence the impact of a rejection episode, and if renal function recovers fully, there appears to be no survival disadvantage. Randomized clinical trials in renal transplant patients have generally shown that there are fewer acute rejection episodes with tacrolimus compared with cyclosporine, although with contemporary regimens, including mycophenolate acid, this difference is less marked than previously. In randomized trials, kidney graft survival rates with cyclosporine and tacrolimus have proven similar. Large-scale registry analyses have consistently shown no graft survival benefit with tacrolimus vs cyclosporine, and indeed, 2 such analyses have reported significantly higher graft survival with cyclosporine-based immunosuppression compared with tacrolimus in living-donor kidney transplant patients receiving mycophenolate mofetil. There are no reports of improved patient survival with either calcineurin inhibitor after kidney transplantation. In conclusion, the perception of better efficacy with tacrolimus vs cyclosporine based on the incidence of acute rejection is not supported by a difference in graft or patient survival after kidney transplantation.