Background: Prior to 2009, assessment and allocation of expanded criteria donor kidneys (ECD) in Singapore for kidney transplantation was based on clinical criteria. However, from 2009 onwards, explant biopsies were performed to assess suitability of ECD kidneys for transplantation as well as to determine allocation as single or dual kidney transplants. This study examines the outcomes of ECD kidney transplants before and after the implementation of explant biopsy assessment. It also examine whether outcomes of ECD kidney transplants compared to standard criteria donor (SCD) kidney transplants has improved following explant biopsy assessment.
Methods: This was a single-centre retrospective cohort study, where we examined post-transplant outcomes of recipients of ECD and SCD kidney transplants. All deceased donor kidney transplant recipients during the period of 1st November 2005 to 31st October 2017 were included in the study, except for 6 cases that were excluded from analysis as they had died or lost their graft due to a hepatitis C outbreak in 2015. Patients were stratified based on date of transplant; those with transplants done before 1st December 2009 were grouped into Era 1 while those done after into Era 2. Outcomes of ECD kidney transplant recipients in Era 1 and 2 were compared to each other, and to SCD kidney transplant recipients from the same era. Of note, all patients received antibody induction in Era 2.
Results: The study population comprised a total of 276 kidney transplant recipients (142 in Era 1, 134 in Era 2). ECD kidney transplants were performed in 28.9% (n=41) in Era 1 versus 38.8% (n=52) in Era 2. Among ECD kidney transplants between Era 1 and Era 2, 5-year graft survival (70.7% vs. 81.6%; p=0.132) and 5-year patient survival (87.8% vs. 94.7%; p=0.111) were higher in Era 2 but not statistically different. Between SCD and ECD kidney transplants, 5-year graft survival of ECD kidney transplants was worst than SCD among in Era 1 (70.7% vs. 87.1%; p=0.028) but comparable to SCD in Era 2 (81.6% vs. 82.1%; p=1.000). Compared to Era 1 ECD kidney transplants, Era 2 ECD kidney transplants experience lower early rejection rates  (9.6% vs. 31.7%; p=0.009) and shorter length of transplant surgery stay  (13 days vs. 19 days; p=0.018). But on 5-year follow-up, there was no significant differences in renal function or rejection rates.
Conclusion: The introduction of explant biopsies to assess and allocate ECD kidneys has improved graft and patient survival of ECD kidney transplants. Furthermore, in the era of explant biospies, graft survival of ECD kidney transplants are comparable to their SCD coutnerparts. The introduction of antibody induction has also improved rejection rates among ECD kidney transplants, shortening stays in hospital.