Assessment of the Utility of Kidney Histology as a Basis for Discarding Organs in the United States: A Comparison of International Transplant Practices and Outcomes

Abstract

Background: Many kidneys donated for transplant in the United States are discarded because of abnormal histology. Whether histology adds incremental value beyond usual donor attributes in assessing allograft quality is unknown.

Methods: This population-based study included patients who received a deceased donor kidney that had been biopsied before implantation according to a prespecified protocol in France and Belgium, where preimplantation biopsy findings are generally not used for decision making in the allocation process. We also studied kidneys that had been acquired from deceased United States donors for transplantation that were biopsied during allocation and discarded because of low organ quality. Using donor and recipient characteristics, we fit multivariable Cox models for death-censored graft failure and examined whether predictive accuracy (C index) improved after adding donor histology. We matched the discarded United States kidneys to similar kidneys transplanted in Europe and calculated predicted allograft survival.

Results: In the development cohort of 1629 kidney recipients at two French centers, adding donor histology to the model did not significantly improve prediction of long-term allograft failure. Analyses using an external validation cohort from two Belgian centers confirmed the lack of improved accuracy from adding histology. About 45% of 1103 United States kidneys discarded because of histologic findings could be accurately matched to very similar kidneys that had been transplanted in France; these discarded kidneys would be expected to have allograft survival of 93.1% at 1 year, 80.7% at 5 years, and 68.9% at 10 years.

Conclusions: In this multicenter study, donor kidney histology assessment during allocation did not provide substantial incremental value in ascertaining organ quality. Many kidneys discarded on the basis of biopsy findings would likely benefit United States patients who are wait listed.

Keywords: epidemiology and outcomes; kidney biopsy; kidney transplantation; pathology; transplant outcomes.

Graphical abstract

Figure 1.

After matching, the kidneys were highly similar in terms of KDRI and histological features of glomerulosclerosis, interstitial fibrosis/tubular atrophy (IFTA), and arteriosclerosis (CV). The figure shows the distributional balance of the KDRI score and kidney histology before and after matching kidneys discarded in the United States to similar kidneys transplanted in the French derivation cohort. Overall, a total of 493 (45%) United States kidneys discarded due to histology were matched to kidneys transplanted in France.

Figure 2.

Kidneys transplanted in France matched to discarded US kidneys had survival similar to French expanded criteria donor kidneys. The figure shows Kaplan–Meier curves of allograft survival rates for kidneys transplanted in France matched and unmatched to United States discarded kidneys. (A) The allograft survival probability of the kidneys transplanted matched to United States discarded kidneys (red curve) to the rest of the population (unmatched kidneys; black curve). (B) The allograft survival probability of the matched kidneys (red curve) to the rest of the population according to the expanded criteria donor (ECD) status (kidneys transplanted with standard criteria donor [SCD], solid black curve; kidneys transplanted with ECD, dashed black curve). Among the recipients of the matched kidneys transplanted in France, 284 (57.61%) were men, 58 (11.76%) had diabetes, 39 (7.94%) were pre-emptive transplantations, 75 (15.21) had a prior kidney transplant, 107 (21.70%) had a DSA at the time of transplantation, the mean cold ischemia time was 18.99±7.64 hours, and 163 (33.75%) had delayed graft function.