Results of the Minnesota randomized prospective trial of cyclosporine versus azathioprine-antilymphocyte globulin for immunosuppression in renal allograft recipients

Between September 26, 1980 and June 8, 1984, 246 splenectomized, transfused renal allograft recipients were randomized to treatment with either cyclosporine (CsA)-prednisone (n = 131) or azathioprine (Aza)-prednisone-antilymphocyte globulin (n = 115). On December 31, 1984, actuarial patient survival rates at three years were 89% in the CsA group and 90% in the Aza group, and the corresponding graft survival rates were 82% and 79% (statistically insignificant differences). The results were also compared separately in diabetic and nondiabetic patients and in recipients of related and cadaver donor grafts; only in the subgroup of diabetic recipients of cadaver kidneys were the differences in graft survival rates significantly different between CsA- and Aza-treated patients. The incidence of posttransplant acute tubular necrosis was similar in CsA- and Aza-treated patients (33% v 27%), but the duration was significantly longer in CsA- than in Aza-treated recipients (15.7 +/- 18.4 v 7.7 +/- 3.0 days). Rejection episodes and infections (particularly CMV) occurred significantly less frequently in CsA- than in Aza-treated patients. Mean serum creatinine levels were significantly higher in CsA- than in Aza-treated recipients (2.0 +/- 0.6 v 1.5 +/- 0.5 mg/dl). Treatment of hypertension and hyperkalemia was required significantly more frequently in the CsA-treated patients than in the Aza-treated patients. Initial mean hospitalization time was significantly shorter in the CsA group than in the Aza group (15.6 +/- 9.5 v 19.8 +/- 10.7 days). In the CsA group, 19% of the patients were switched to Aza and 35% had Aza added to their regimen with a concomitant lowering of the CsA dose because of nephrotoxicity. The results of our randomized trial are at variance with those of others in that the graft survival rates in our trial were not different between CsA and Aza-treated patients, primarily because our conventionally-treated patients had a higher graft survival rate than in the other trials. The advantages of CsA (fewer rejection episodes, fewer infections, shorter hospitalization) outweigh the disadvantages (higher serum creatinine, more hypertension), and thus we believe it should be used in most renal allograft recipients, perhaps in combination with Aza so that a lower dose of CsA can be used and the side effects minimized--a regimen that we are currently evaluating.