Background: Pediatric kidney transplantation has been the gold standard for children with end stage renal disease (ESRD). Changes in pediatric kidney transplant has come a long way in Korea since 1979; from changes in immunosuppressants and induction therapies to indications for transplant in children. This study investigates the long term outcomes of 40 years of pediatric kidney transplantation at a single center in Korea.
Method: Pediatric kidney transplantation performed at a single institution in Korea from 1979 to 2018 was retrospectively reviewed. The patient and graft survivals were analyzed by various patient factors using the Kaplan-meier curve, log rank test, univariate and multivariate Cox-proportion hazard models. Different aspects such as causes of graft failure, recurrence of the primary disease and incidence of malignancy that are unique to pediatric kidney transplant were also analyzed.
Results and Discussion: Total of 402 pediatric patients underwent 414 kidney transplantations from 1979 to 2018 with a mean follow up duration of 150.4 months. The overall death censored graft survival and patient survival at 10 years was 76.0% and 96.7% respectively. There was a significant increase in 5 year graft survival over the four decades from 57.1% to 93.0% (p<0.001). In the multivariate analysis, tacrolimus over cyclosporine (p=0.008, HR=0.290, 95%CI 0.115-0.727), mycophenolate mofetil over azathioprine (p=0.011, HR=0.394, 95%CI 0.192-0.809) and retransplant (p=0.005, HR=3.378, 1.449-7.875) were the only significant risk factors that effected graft survival. The single most common cause of ESRD in pediatric kidney recipients was focal segmental glomerulosclerosis (FSGS, 22.8%) followed by reflux nephropathy (13.4%) and renal congenital anomalies (7.7%). Although not significant, the 10 year graft survival was higher in patients with nephronophthisis (NPHP) compared to patients with congenital anomalies(renal dysplasia, hypoplasia and reflux nephropathy) and the group of patients with FSGS, IgA nephropathy and HUS (91.6% vs 83.4% and 70.9%, p=0.068). Recurrence of the primary disease was a significant risk factor among the recipients with FSGS, IgA nephropathy and HUS (p=0.019, HR=2.172, 95%CI 1.134-4.162) and the 10 year graft survival with or without recurrence was 59.9% and 74.7% respectively. Recurrence of primary disease (14.0%) and noncompliance (8.5%) were the third and fourth cause out of 129 graft failures (31.2%) followed by chronic and acute rejection (46.5%, 15.5%).
Conclusion: Graft survival has improved over the 40 years of pediatric kidney transplantation at our institution due to changes in immunosuppressants from cyclosporine to tacrolimus and from azathioprine to mycophenolate mofetil over time. However, recurrence of FSGS, IgA nephropathy and HUS effects worse graft survival and both recurrence and noncompliance still remain as one of the crucial causes of graft failure in pediatric kidney transplantation.