Risk factors and outcome of expanded-criteria donor kidney transplants in patients with low immunological risk

QUESTIONS UNDER STUDY: The aim of this study was to evaluate risk factors and outcome of expanded-criteria donor (ECD) kidney transplants in patients with low immunological risk. METHODS: We evaluated graft survival and graft function in 265 recipients with low immunological risk defined as the absence of pretransplant donor-specific HLA antibodies. RESULTS: A total of 112 (42%) kidneys derived from ECD and 153 (58%) from standard-criteria donors (SCDs). Overall, in a multivariate Cox regression, ECD status was the only significant risk factor for graft failure (hazard ratio [HR] 2.31, 95% confidence interval [CI] 1.22-4.37; p = 0.01). In the SCD group there was an increased risk for graft failure with increasing recipient age (HR 1.06 per year, CI 1.01-1.10; p = 0.02) and in the ECD group a trend for risk reduction for recipients treated with tacrolimus (Tac) (HR 0.46, CI 0.20-1.06; p = 0.07). One, three and five-year graft survival of ECD kidneys was significantly better when recipients were treated with Tac (95%, 88% and 72%, respectively) than when they were treated without Tac (73%, 65% and 50%, respectively) (p = 0.008). At three years, ECD kidneys had a lower median estimated creatinine clearance (eCrCl) than SCD kidneys (37 vs 58 ml/min, p < 0.001). Within the ECD group, recipients treated with Tac had a higher median eCrCl than those treated without Tac (41 ml/min vs 33 ml/min, p = 0.004). Graft function from one to three years was preserved in ECD recipients treated with Tac (median change 0.0 ml/min, p = 0.4) compared with those treated without Tac (median change -3.2 ml/min, p = 0.005). CONCLUSION: Tac-based immunosuppression seems to improve graft survival and to preserve graft function in ECD kidneys with low immunological risk.