Effect of the immunosuppressive treatment on long-term renal graft survival

Background. Although new immunosuppressive agents have improved the results of renal transplants (RTs), long-term graft loss remains high. We evaluated the impact of different immunosuppressive regimens on patient and graft survival. Methods. Data from 3365 patients receiving cadaver RTs in Spain during the years 1990, 1994 and 1998 were retrospectively analysed. All data were entered into a specially designed database. Graft and patient survival rates were estimated by the Cox regression method and results expressed as percentage survival. A maximum-likelihood estimate of the projected graft half-life (median value) was calculated by Weibull regression. Results. In 1990 graft and patient survival differed significantly from the other treatment years (P = 0.0006 and P = 0.0101, respectively). The risk of graft loss was significantly higher for cyclosporine (CsA), prednisone (P) and azathioprine (Az) than for CsA+P, which in turn was higher than for CsA+P plus polyclonal antibodies [antilymphocyte globulin (ALG)/antithymocyte globulin (ATG)]. Risk of patient death was also significantly higher for CsA + P + Az than for CsA + P. No significant differences between treatment groups were found in graft and patient survival for 1994 and 1998. The projected median graft life for patients with the most used immunosuppressive regimen for each year was 12.9 years for CsA + P + Az and 15.6 years for CsA + P plus mycophenolate mofetil (MMF). Conclusions. Triple therapy with Az in 1990 and 1994 and with MMF in 1998 were the most frequently used immunosuppressive regimens in the Spanish kidney transplant population. The best results were seen after induction therapy with polyclonal antibodies.