Pretransplant biopsy in expanded criteria donors: do we really need it?

Renal Resistance Trend During Hypothermic Machine Perfusion Correlates With Preimplantation Biopsy Score in Transplantation of Kidneys From Extended Criteria Donors

BACKGROUND

Graft quality from extended criteria donors (ECDs) is extremely wide, and a reliable evaluation parameter is required. So far, biopsy is widely used to evaluate ECD organs and to decide whether double (DKT) or single (SKT) kidney transplantation should be performed. The aim of this study is to compare renal resistance (RR) trend during hypothermic machine perfusion (HMP) with a preimplantation biopsy score.

METHODS

From December 2014 to April 2020, HMP has been systematically applied to all organs from ECDs for at least 3 hours. All grafts underwent a preimplantation biopsy histologic assessment with Karpinski's score. SKTs or DKTs were performed accordingly. RR trend during the first 180 minutes of HMP was compared with the biopsy score.

RESULTS

Eighty-three kidneys were used to perform 57 transplantations (31 SKTs and 26 DKTs). A biopsy confirmed suitability for transplantation in all cases, and the median score was 4 (range, 2-7). Kidneys with a score of 5 to 7 had significantly higher RR value than kidneys with a score of 0 to 4 at basal time (3.35 vs 2.71; P = .074), at 60 minutes (1.24 vs 0.94; P = .031), at 120 minutes (1.10 vs 0.81; P = .010), and at 180 minutes (1.00 vs 0.77; P = .022). A cutoff value of RR ≥0.88 at 120 minutes of perfusion had the best sensibility and specificity (0.71 and 0.75, respectively) to discriminate kidneys with a score of 5 to 7 from kidneys with a score of 0 to 4. No differences were found in postoperative outcomes between SKT and DKT recipients.

CONCLUSIONS

RR trend during HMP correlates with the histologic score in ECD kidneys and can be used as a reliable parameter to evaluate graft quality.

Strategies for an Expanded Use of Kidneys From Elderly Donors

The old-for-old allocation policy used for kidney transplantation (KT) has confirmed the survival benefit compared to remaining listed on dialysis. Shortage of standard donors has stimulated the development of strategies aimed to expand acceptance criteria, particularly of kidneys from elderly donors. We have systematically reviewed the literature on those different strategies. In addition to the review of outcomes of expanded criteria donor or advanced age kidneys, we assessed the value of the Kidney Donor Profile Index policy, preimplantation biopsy, dual KT, machine perfusion and special immunosuppressive protocols. Survival and functional outcomes achieved with expanded criteria donor, high Kidney Donor Profile Index or advanced age kidneys are poorer than those with standard ones. Outcomes using advanced age brain-dead or cardiac-dead donor kidneys are similar. Preimplantation biopsies and related scores have been useful to predict function, but their applicability to transplant or refuse a kidney graft has probably been overestimated. Machine perfusion techniques have decreased delayed graft function and could improve graft survival. Investing 2 kidneys in 1 recipient does not make sense when a single KT would be enough, particularly in elderly recipients. Tailored immunosuppression when transplanting an old kidney may be useful, but no formal trials are available.Old donors constitute an enormous source of useful kidneys, but their retrieval in many countries is infrequent. The assumption of limited but precious functional expectancy for an old kidney and substantial reduction of discard rates should be generalized to mitigate these limitations.