Introduction: Clinical practice guidelines to standardise immunosuppressive regimens in UK paediatric renal transplantation exist1. In our centre we follow the steroid minimisation immunosuppression protocol (basiliximab induction, tacrolimus, mycophenolate mofetil (MMF) and rapid steroid wean) for our standard risk recipients.
MMF has known gastrointestinal (GI) side effects which we postulate may be more commonly experienced by the younger children resulting in them changing immunosuppression within the first-year post transplant.
Aim: Retrospective study to investigate whether younger children are less likely to tolerate MMF within the first year after renal transplant.
Method: Five-year retrospective review of all paediatric renal transplant recipients following the steroid minimisation protocol for their 1st graft and followed up in our centre. Data collected included demographics, HLA mismatch, viral status, eGFR at one year and immunosuppression at one year, documenting the rationale to any changes from their initial immunosuppression protocol.
Results: 48 patients, 24(50%) male included in the study. All had a HLA mismatch of 3 or less. 34(71%) had living donor kidneys. Mean(range) age at time of transplant 8.9(1.8-17.4) years(y).
21(44%) patients remained on the steroid minimisation protocol at 1y post-transplant with mean age of 10.3(range 3.5-16.68)y. eGFR at 1y was 67.8(41-131.9)ml/min/1.73m2 with 1/23 patients having biopsy proven rejection within the 1st year post transplant. 2 patients developed donor specific antibodies (DSAs) within the 1st year.
27(56%) patients deviated from this protocol with mean age of 8(range 1.8-17.4)y. 14 of these 27 patients (52%) with mean age of 8.9(range 2-14.3)y had changes to their immunosuppression regimes due to adverse GI side effects secondary to MMF. The primary reason for changes to immunosuppression in the remaining patients with mean age of 10.7(range 1.8-17.4)y included viraemias (6(EBV 4, BK 1, CMV 1)), rejection (3), neutropenia (2) and difficulty obtaining therapeutic tacrolimus levels (2). eGFR at 1y was 61(30-102.8)ml/min/1.73m2 and 2 recipients developed DSAs. 5/27 patients had biopsy proven rejection in the 1st year of transplant and 2 patients within this group developed post-transplant lymphoproliferative disorder.
Conclusion: Over half the paediatric RTRs started on the steroid minimization protocol had changed from this protocol by 1y post-transplant with the most common reason being due to GI intolerance of MMF. This was experienced more commonly in the younger cohort. Consideration should be given to using the alternative National immunosuppression protocol consisting of basiliximab induction with tacrolimus, azathioprine and steroids in selected recipients who may be less likely to tolerate MMF.

Reference
1) Dudley, J et al. Clinical practice guidelines standardisation of immunosuppressive and anti-infective drug regimens in UK paediatric renal transplantation: the harmonisation programme