Tacrolimus/Sirolimus Versus Tacrolimus/Mycophenolate in Kidney Transplantation: Improved 3-Year Graft and Patient Survival in Recent Era

BACKGROUND: Registry analyses suggest that tacrolimus (TAC)/mycophenolate (MPA) immunosuppression is associated with superior kidney graft survival versus TAC/sirolimus (SRL). Large single-center experience can assist in clarifying these findings, by examining outcomes related to specific utilization practice. METHODS: We retrospectively examined the outcomes of 518 consecutive first renal transplants at a single center treated with TAC/SRL (n=307) or TAC/MPA (n=211) with prednisone. Graft and patient survival, acute rejection, and 1-year glomerular filtration rate (GFR) were analyzed by era of transplant (2000-2002 vs. 2003-2006). Changes in TAC/SRL utilization between eras included elimination of the SRL loading dose and a reduction in TAC target trough concentrations. RESULTS: Three-year graft survival with TAC/SRL was lower when first used (2000-2002) because of a higher incidence of patient death, primarily due to cardiovascular causes. Survival improved from 85.3% to 95.9% between 2000 to 2002 and 2003 to 2006 (P=0.001), with comparable graft and patient survival between TAC/SRL and TAC/MPA cohorts, confirmed following multivariable analysis controlling for donor and recipient factors. Rates of BK virus and acute rejection were comparable, but a higher incidence of hyperlipidemia, anemia, posttransplant diabetes, and a lower 1-year GFR (57.6 vs. 63.1 mL/min, P=0.008) was noted in the TAC/SRL cohort. CONCLUSIONS: These data, as the largest long-term single-center report comparing TAC/SRL with TAC/MPA in kidney transplantation, demonstrate worse patient survival initially with TAC/SRL, with improved outcomes in a later era that were temporally associated with reduced TAC exposure. Differences in cardiovascular risk factors and 1-year GFR highlight the need for further investigation of the optimal utilization of SRL in kidney transplantation.