Reasons for dose reduction of mycophenolate mofetil during the first year after renal transplantation and its impact on graft outcome

Summary Mycophenolate mofetil (MMF) decreases the risk of acute rejection and is associated with improved graft survival in renal transplant recipients. However, MMF-related side effects often necessitate dose reduction, which may expose patients to a higher risk of acute rejection and graft loss. This study's aim was to examine the reasons for MMF dose reduction during the first post-transplant year and its impact on acute rejection, overall and death-censored graft loss. Methods: Single-center retrospective analysis of 749 renal transplant recipients treated with MMF in their initial maintenance immunosuppressive protocol. Results: In 365 patients (48.7%) a total of 530 MMF dose reductions were done. Reasons for reduction were hematologic toxicity (46.5%), infection (16.1%), gastrointestinal side effects (12.3%), malignancy (2.1%), study protocol (14.6%), and unknown (13.5%). MMF dose reduction as such was not an independent predictor of acute rejection or graft survival, although reductions in ≥50% of initial dose were significantly associated with acute rejection. Conclusions: In this retrospective cohort, by far the most important reason for MMF dose reduction during the first post-transplantation year was hematologic. MMF dose reductions in ≥50% increased the risk of acute rejection but did not compromise graft survival.