Comparison of long-term actual renal allograft survival in mycophenolate mofetil and azathioprine-based triple drug immunosuppression protocols

Introduction. The use of mycophenolate mofetil (MMF) in renal transplantation results in a 50% lower incidence of acute rejection compared to azathioprine (AZA). However, the graft survival reports are conflicting: the European trial and US database analysis suggest better survival with MMF, an observation that was not seen in the US and tricontinental studies. Methods. We retrospectively reviewed our single-center experience (60% African-Americans) comparing the serum creatinine (SCr) values and 3-year actual graft survival with MMF versus AZA-based immunosuppression. Group I included patients transplanted between January 1990 and December 1992 on cyclosporine (CSA), AZA, and steroids; group II subjects, from January 1996 to December 1998 on CSA, MMF, and steroids. We analyzed SCr and all causes of graft losses at 3, 6, 12, 18, 24, and 36 months posttransplantation. Results. The patient demographics were similar in both groups as was the mean SCr values at different times. The time-group interaction for SCr, the Kruskal-Wallis test for SCr for different categories (< 1.5, 1.5 to 2.0, 2.0 to 2.5, and > 2.5 mg/dL) and the all-cause graft loss between the two groups were not significantly different. Conclusion. Our results failed to show better long-term actual graft survival despite the 6-year interval between the two groups. These findings agree with the results of the United States and the tricontinental studies. A lower incidence of acute rejection early after transplantation observed with MMF may not always translate into a long-term benefit, possibly due to the influence of nonimmunological factors, such as hypertension, calcineurin inhibitor toxicity, more frequent cytomegalovirus infections, and increased attempts to withdraw steroids using MMF-based protocols.