Factors associated with improvement in deceased donor renal allograft function in the 1990s

The decade of the 1990s saw an improvement in cadaveric renal graft function and dramatic reduction in the acute rejection (AR) rate. The purpose of this study was to determine whether the reduction in rejection rate was the primary cause of the improvement in graft function seen and whether this improved long-term graft survival. All adult patients who received a cadaver renal transplant between 1991 and 2000 and had graft survival of at least 6 mo and complete data for creatinine at 6 A-OKmo, HLA mismatch, delayed graft function, and acute rejection (AR) were identified in the United Network for Organ Sharing database. A total of 40,164 cases that met the inclusion criteria were identified. The mean Modification of Diet in Renal Disease GFR at 6 mo improved from 49.94 ml/min per 1.73 m² in 1991 to 54.59 ml/min per 1.73 m² in 2000 (P < 0.001). The improvement in GFR was not gradual but occurred over a 4-yr period between 1994 and 1997, coinciding with the introduction of new immunosuppressive agents mycophenolate mofetil and tacrolimus into maintenance immunosuppression regimens. The improvement was seen in all subgroups of patients, even patients without clinical AR or delayed graft function. The magnitude of improvement in patients without clinical AR was similar to that seen in patients with AR. The drop in clinical AR rate accounted for a minority of the improvement in graft function in the 1990s. Other factors, such as reduced drug toxicity and improved control of subclinical rejection, seem to account for the majority of the improvement. This improvement in graft function at 6 mo did not translate into improved long-term graft survival, however.