Association of Transit Time With Cold Ischemic Time in Kidney Transplantation

This cross-sectional study examines the association between transit time and cold ischemic time for adult, deceased kidney transplant donors.


Introduction
The Organ Procurement and Transplant Network (OPTN) is developing an organ allocation framework called Continuous Distribution. This proposed allocation system would incorporate medical urgency, posttransplant survival, biological factors, access, and placement efficiency. 1 It would derive a candidate's score by weighting the scores of each subcomponent.
There are concerns about how to balance placement efficiency via cold ischemic time (CIT), defined as the time between cross-clamp and anastomosis, with other allocation goals. 2 Placement efficiency is difficult to assess in kidney allocation because of the lack of organ transit data. 3,4 Hence, understanding the association between organ transit time and CIT is important.

Methods
In this cross-sectional study, we used data from the OPTN, which collects data on donors, wait-listed candidates, and transplant recipients in the US. The data reported were supplied by the United Network for Organ Sharing as the contractor for the OPTN. We identified 950 adult, deceased kidney transplant donors between August 2, 2019, and August 1, 2020, from whom kidneys were procured by LifeGift and LifeShare of Oklahoma.
We obtained institutional review board approval from Advarra, which declared the study exempt from the requirement for informed consent because the data were deidentified, in accordance with 45 CFR 46.104(d) (4). This study adheres to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cross-sectional observational studies.

The Health Resources and Services Administration, US Department of Health and Human
Services, provides oversight to the activities of the OPTN contractor. We received transportation details (ie, order details, pickup time, delivery time, and method of transportation) from the transportation vendor identified by both organ procurement organizations as their primary vendor.
We performed a geospatial linkage, on the basis of the latitude and longitude of the vendor's delivery address and the transplant center's address, because the addresses did not exactly match. We We performed a subanalysis on 246 driven and 66 flown organs. We also examined a more restrictive geospatial link (1 mile) to test the robustness of our results. We performed our analyses in R statistical software, version 4.0.5 (R Project for Statistical Computing). Data were analyzed from October 2020 to September 2021. Table 1 describes our data set, which included 316 adult, deceased kidney transplant donors.

Results
Although flown organs have higher CIT than driven organs, Table 2 illustrates that the correlation coefficient between transit time and CIT was low (ρ = 0.20; P < .001); in addition, our subanalysis of flown organs also demonstrated that the association between transit time and CIT was not significant (ρ = 0.16; P = .18). The correlation coefficient between distance and CIT (ρ = 0.21; P < .001) was higher than that between transit time and CIT. The correlation coefficient between distance and transit time was high (ρ = 0.67; P < .001). Both postprocurement time and transplant time were associated with CIT (postprocurement time: ρ = 0.63; P < .001; transplant time: ρ = 0.54; P < .001).
Sensitivity analyses indicated our results were robust to our linkage definition.

Discussion
To our knowledge, this cross-sectional study was the first to quantify the subcomponents of CIT and aligned with previous research on CIT and distance. 5 Our data suggested that transit time had a low correlation with CIT, but transplant and postprocurement time were moderately correlated with CIT.
A limitation of our study was that we obtained transit data on adult kidney transplants from 2 organ procurement organizations. The association between transit time and CIT may have varied by both geographical region and the organ in question. These findings are important given the impact of transit and CIT on organ allocation. 6 Efforts to ensure low CIT should focus on identifying and reducing practices associated with increased postprocurement and transplant time.