Increased Rates of Kidney Discard in the Era of COVID-19 and Recent KAS Policy Implementation : Transplantation

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Increased Rates of Kidney Discard in the Era of COVID-19 and Recent KAS Policy Implementation

Özer, Yunus BSc1; Kaplan, Salim BSc1; Sandikçi, Burhaneddin PhD1; Gupta, Gaurav MD2; Tanriover, Bekir MD, MPH, MBA, FAST3

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doi: 10.1097/TP.0000000000004321

The COVID-19 pandemic has impacted transplant activity negatively across the United States.1,2 The early phase of the pandemic witnessed decreased new waitlist additions and transplant rates and increased waitlist mortality and graft failure.

During the COVID-19 pandemic, the Organ Procurement and Transplantation Network (OPTN) introduced a major change in the kidney allocation system (KAS) policy on March 15, 2021, removing Donation Service Area (DSA) and OPTN region, introducing circles of a radius 250 nautical miles around donor hospitals, and adding allocation proximity points (the KAS-250 policy). The OPTN 6-mo postimplementation report indicated that number of deceased donor kidney transplants increased, whereas waitlist mortality and discard rate both decreased.3

In this retrospective study, we evaluated kidney discard patterns over time and their associations with the COVID-19 pandemic and the KAS-250 policy changes using OPTN data from October 31, 2008, through March 31, 2022, divided into 4 eras: (i) pre-KAS era: October 31, 2008, to December 3, 2014; (ii) KAS era: December 4, 2014, to March 10, 2020; (iii) COVID-19 only era: March 11, 2020, to March 14, 2021, covering the first year of COVID-19 pandemic until the start of the KAS-250 policy; and (iv) KAS-250 era: March 15, 2021, to March 31, 2022, covering the first year of the KAS-250 policy implementation and overlaps with the second year of the COVID-19 pandemic.

The mean monthly discard rate increased significantly across the 4 eras: from 18.47% to 19.66% to 21.81% to 24.78% (P < 0.01 for all pairwise comparisons, Tables S1–S2, SDC, Our trends analysis (Figure 1) revealed that discard rate remained stable around its respective mean values within the pre-KAS and KAS eras (similar to previously reported),4 but it started increasing, albeit slowly, in the COVID-19 only era (trend P value: 0.30), and the increase accelerated in the KAS-250 era (trend P value: 0.01), resulting in a peak rate of 28.34% in November 2021 followed by a downward trend concluding with 23.40% in March 2022. Discard rate, however, was not uniformly distributed across the United States (Figure 2). Although the 30% threshold was exceeded in only 1 DSA (within OPTN Region 2—Northeast), in each of the pre-KAS and KAS eras, it was exceeded in 5 DSAs (within OPTN Regions 3—Southeast,5—Northeast, and 9—West) in the COVID-19 only era and in 10 DSAs (within OPTN Regions 2—Northeast, 3—Southeast, 11—East, 5—West, 6—Northwest, and 10—Midwest) in the KAS-250 era.

Discard rate trends for deceased donor kidneys in the United States by donor recovery year and major events (kidney allocation policy changes and COVID-19 pandemic). DSA, donation service area; KAS, kidney allocation system.
Geographic changes in deceased donor kidney discard rate in the United States and its evolution over 4 eras. Discard rate is calculated for each OPO’s DSA in aggregate. State and county boundaries are indicated in thick and thin white colored lines, respectively. DSA, donation service area; KAS, kidney allocation system; OPO, organ procurement organization.

Across the 4 eras, the proportion of kidneys recovered for transplantation with high Kidney Donor Profile Index (KDPI), namely, KDPI 35% to 85% and KDPI >85%, increased steadily from 47.82% and 13.18% in the pre-KAS era to 51.99% and 16.18%, respectively, in the KAS-250 era (Tables S1–S2, SDC, These trends coupled with rising discard rates for KDPI 35% to 85% and KDPI >85% kidneys (from 19.65% and 56.39% in the pre-KAS era to 23.93% and 66.48%, respectively, in the KAS-250 era) (Figure S1, SDC, mostly accounted for the overall increasing trend observed in the KAS-250 era (Figure 1). “No recipient located—list exhausted” has become an increasingly dominant reason for discards (20.53% in the pre-KAS versus 61.84% in the KAS-250 era) and surpassed abnormal biopsy findings by a factor of 4 in the KAS-250 era (14.50% versus 61.84%). Based on a propensity score (using inverse probability of treatment weighting) adjusted multivariable mixed effect logistic regression (accounting for the random effects of organ procurement organizations [OPOs]), the odds of discard, compared with the pre-KAS era (the control group), increased by 2% (95% confidence interval [CI] for odds ratio: 0.95-1.09) during the KAS era, by 12% (CI: 1.03-1.22) during the COVID-19 only era, and by 24% (CI: 1.13-1.36) during the KAS-250 era (Table S3, SDC,

It is not easy to pin down a single reason for recent increase in discard rates. Potential explanations include (1) the enhanced strive of OPOs to expand the donor pool and to recover more (high KDPI) organs for transplant4,5,6; (2) COVID-19 pandemic-related strain on health care systems (eg, lack of hospital beds, COVID-19–infected providers and candidates, socioeconomical disruptions, insufficient staffing and machines in dialysis units)7,8,9,10,11; (3) increased risk averse behavior of transplant center during the COVID-19 pandemic2,6,12; (4) the impact of KAS-250 policy (difficulties in transporting organs, prolonged cold ischemia, lack of machine perfusion devices sharing between OPOs)13; (5) lack of efficient expedited placement of hard-to-place kidneys)14; and (6) the growing number of potential donors with COVID-19 infection and a lack of high-quality evidence to guide decisions regarding deceased donation.5

Knowing that “No recipient located—list exhausted” has become the major reason for discards in the KAS-250 era, elimination of logistic barriers, refining kidney allocation inefficiencies, and the OPTN’s close monitoring on transplant metrics will be critical in effective handling of discards.


This work was supported in part by Health Resources and Services Administration contract 234-2005-370011C. The content is the responsibility of the authors alone and does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the US Government.


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