Background: Late introduction of mycophenolate mofetil (MMF) is used in renal transplant patients to allow calcineurin inhibitor (CNI) withdrawal. This change in treatment may alter the immunosuppressive load predisposing patients to infections. To assess this we have analysed infection rates in 30 consecutive patients with chronic allograft nephropathy commenced on MMF for CNI withdrawal. Methods and results. The study period was from 12 months pre-commencement to 12 months post-commencement. At commencement, patient mean age was 51.2 +/- 12.9 years and mean time post-transplant was 3170 +/- 2130 days. Estimated glomerular filtration rate (eGFR) at the start of the study period and at conversion was 30.7 +/- 12.1 ml/min and 23.1 +/- 9.9 ml/min, respectively. The mean dose of MMF post-conversion was 1575 +/- 428 mg/day. Estimated GFR had stabilized at 12 months post-conversion to 25.3 +/- 12.2 ml/min. There was a significant increase in infections following conversion: pre-conversion, 26.7% (8/30); post-conversion, 66.6% (20/30) (chi(2) = 24.5, P < 0.0005). There was an inverse correlation between eGFR at conversion and infection rates post-conversion (r = -0.379, P = 0.039). There were no hospitalizations for infection pre-conversion and 6 patients (20%) were hospitalized post-conversion, for a total of 285 days (7-107).
Conclusion: There is significant morbidity associated with an increased incidence of infection after late introduction of MMF at standard doses in renal transplant recipients. This risk may be related to GFR at the time of conversion.