Background: The introduction of cyclosporine (CsA) in kidney transplantation has improved early graft survival. However, its long-term use is associated with impairment of renal function and increased cardiovascular risk factors. To avoid CsA-related long-term adverse effects, patients were converted to either azathioprine (AZA) or mycophenolate mofetil (MMF) 1 year after transplantation.
Methods: Between September 1995 and January 1997, 64 stable renal transplant recipients on CsA and prednisone treatment were included in a prospective, randomized study. Patients were randomized for conversion of CsA to 2 mg/kg AZA (n=30) or 1 g of MMF twice daily (n=34). All patients remained on low-dose steroids. To decrease the total immunosuppressive load, a dose reduction in MMF and AZA was performed at 4 and again at 8 months after conversion. Mycophenolic acid trough levels were measured at regular intervals.
Results: After conversion, a decrease in serum creatinine was found for both groups: for MMF, 132 to 109 micromol/L (P=0.016); and for AZA, 123 to 112 micromol/L (P<0.0001). After conversion, more acute rejections occurred in the AZA group (11/30) compared to the MMF group (4/34) (P=0.04). Dose reduction of MMF to 500 mg twice daily and of AZA to 1.0 mg/kg elicited three rejections in both groups. The incidence of side effects and infections were similar.
Conclusion: Discontinuation of CsA spared renal function. In patients converted to MMF significantly less rejections occurred compared to patients converted to AZA. Furthermore, dose reduction of both AZA and MMF is possible in the majority (72%) of the patients.