Accelerating kidney allocation: Simultaneously expiring offers

Rescue Allocation Modes in Eurotransplant Kidney Transplantation: Recipient Oriented Extended Allocation Versus Competitive Rescue Allocation-A Retrospective Multicenter Outcome Analysis

BACKGROUND

Whenever the kidney standard allocation (SA) algorithms according to the Eurotransplant (ET) Kidney Allocation System or the Eurotransplant Senior Program fail, rescue allocation (RA) is initiated. There are 2 procedurally different modes of RA: recipient oriented extended allocation (REAL) and competitive rescue allocation (CRA). The objective of this study was to evaluate the association of patient survival and graft failure with RA mode and whether or not it varied across the different ET countries.

METHODS

The ET database was retrospectively analyzed for donor and recipient clinical and demographic characteristics in association with graft outcomes of deceased donor renal transplantation (DDRT) across all ET countries and centers from 2014 to 2021 using Cox proportional hazards methods.

RESULTS

Seventeen thousand six hundred seventy-nine renal transplantations were included (SA 15 658 [89%], REAL 860 [4.9%], and CRA 1161 [6.6%]). In CRA, donors were older, cold ischemia times were longer, and HLA matches were worse in comparison with REAL and especially SA. Multivariable analyses showed comparable graft and recipient survival between SA and REAL; however, CRA was associated with shorter graft survival. Germany performed 76% of all DDRTs after REAL and CRA and the latter mode reduced waiting times by up to 2.9 y.

CONCLUSIONS

REAL and CRA are used differently in the ET countries according to national donor rates. Both RA schemes optimize graft utilization, lead to acceptable outcomes, and help to stabilize national DDRT programs, especially in Germany.

Evaluation of Opening Offers Early for Deceased Donor Kidneys at Risk of Nonutilization

BACKGROUND

Reducing nonutilization of kidneys recovered from deceased donors is a current policy concern for kidney allocation in the United States. The likelihood of nonutilization is greater with a higher kidney donor risk index (KDRI) offer. We examine how opening offers for organs with KDRI >1.75 to the broader waitlist at varying points of time affects usage rates.

METHODS

We simulate kidney allocation using data for January 2018 to June 2019 from Organ Procurement and Transplantation Network. For the simulation experiment, allocation policy is modified so that KDRI >1.75 organs are offered to all local candidates (same donation service area) after a set amount of cold time simultaneously. Open offers to candidates nationally are similarly examined.

RESULTS

Simulation results ( n =50 replications) estimate that opening offers locally for KDRI >1.75 after 10 hours yields a nonutilization rate of 38% (range: 35%-42%), less than the prevailing rate of 55% of KDRI >1.75 kidneys. Opening offers after 5 hours yields 30% (range: 26%-34%), reducing the prevailing nonutilization rate by 45%. Opening offers nationally after 10 and 5 hours yields nonutilization rates of 11% (range: 8%-15%) and 6% (range: 4%-9%) for KDRI >1.75 kidneys, respectively.

CONCLUSIONS

Simulation findings indicate that opening offers and adjusting their timing can significantly reduce nonutilization of high-KDRI kidneys.

Implications of Accumulated Cold Time for US Kidney Transplantation Offer Acceptance

BACKGROUND AND OBJECTIVES

Reducing discard is important for the US transplantation system because nearly 20% of the deceased donor kidneys are discarded. One cause for the discards is the avoidance of protracted cold ischemia times. Extended cold ischemia times at transplant are associated with additional risk of graft failure and patient mortality. A preference for local (within the same donor service area) or low-Kidney Donor Risk Index organs, the endogeneity of cold ischemia time during organ allocation, and the use of provisional offers all complicate the analysis of cold ischemia times' influence on kidney acceptance decision making.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using January 2018 to June 2019 Organ Procurement and Transplantation Network data, we modeled the probability of accepting an offer for a kidney after provisional acceptance. We use logistic regression that includes cold ischemia time, Kidney Donor Risk Index, and other covariates selected from literature. Endogeneity of cold ischemia time was treated by a two-stage instrumental variables approach.

RESULTS

Logistic regression results for 3.33 million provisional acceptances from 12,369 donors and 108,313 candidates quantify trade-offs between cold ischemia time at the time of offer acceptance and donor-recipient characteristics. Overall, each additional 2 hours of cold ischemia time affected acceptance for nonlocal and local recipients (odds ratio, 0.75; 95% confidence interval, 0.73 to 0.77, odds ratio, 0.88; 95% confidence interval, 0.86 to 0.91; P<0.001). For Kidney Donor Risk Index >1.75 (Kidney Donor Profile Index >85) kidneys, an additional 2 hours of cold ischemia time for nonlocal and local recipients was associated with acceptance with odds ratio, 0.58; 95% confidence interval, 0.54 to 0.63 (nonlocal) and odds ratio, 0.65; 95% confidence interval, 0.6 to 0.7 (local); P<0.001. The effect of an additional 2 hours of cold ischemia time on acceptance of kidneys with Kidney Donor Risk Index ≤1.75 (Kidney Donor Profile Index ≤85) was less pronounced for nonlocal offers (odds ratio, 0.82; 95% confidence interval, 0.80 to 0.85; P<0.001) and not significant for local offers.

CONCLUSIONS

The acceptability of marginal organs was higher when placements were nearer to the donor and when cold ischemia time was shorter.

The role of bypass filters in deceased donor kidney allocation in the United States

Kidney transplant centers set organ offer filters enabling all candidates at their center to be bypassed during allocation of deceased donor kidneys from the UNOS Organ Center. These filters aim to increase allocation efficiency by preemptively screening out offers unlikely to be accepted. National data were used to compare filter settings of 175 centers in 2007 and in 2019. We examined characteristics of centers whose settings became increasingly restrictive over time, and associations between filter settings and organ offer acceptance. Overall, centers became more open to receiving offers over time, from a median 62% of filters open to receiving national offers in 2007 to 73% in 2019. Intravenous drug use filter settings changed most, from 63 to 153 willing centers. Centers with more open filter settings had higher transplant volume and offer acceptance ratios across all risk categories despite preemptively screening out fewer offers compared to centers with less open settings, but similar transplant rates. There was significant geographic heterogeneity in the distribution of centers with more open filter settings. Current center bypass filters may impact patients' access to transplantation without achieving their full potential for improving allocation efficiency.

Early Assessment of National Kidney Allocation Policy Change

BACKGROUND

The new kidney allocation changes with elimination of donor service areas (DSAs) and Organ Procurement and Transplantation Network regions were initiated to improve equity in organ allocation. The aim of this evaluation was to determine the operational, financial, and recipient-related effect of the new allocation system on a large rural transplantation program.

STUDY DESIGN

A retrospective, cross-sectional analysis of organ offers, allograft outcomes, and attributed costs in a comparative time cohort, before (December 16, 2020 to March 14, 2021) and after (March 15, 2021 to June 13, 2021) the allocation change was performed. Outcomes were limited to adult, solitary, deceased donor kidney transplantations.

RESULTS

We received 198,881 organ offers from 3,886 organ donors at our transplantation center from December 16, 2020 to June 31, 2021: 87,643 (1,792 organ donors) before the change and 111,238 (2094 organ donors) after the change, for a difference of +23,595 more offers (+302 organ donors). This resulted in 6.5 more organs transplanted vs a predicted loss of 4.9 per month. Local organ offers dropped from 70% to 23%. There was a statistically significantly increase in donor terminal serum creatinine (1.2 ± 0.86 mg/dL vs 2.2 ± 2.3 mg/dL, p < 0.001), kidney donor profile index (KDPI) (39 ± 20 vs 48 ± 22, p = 0.017), cold ischemia time (16 ± 7 hours vs 21 ± 6 hours, p < 0.001), and delayed graft function rates (23% vs 40%, p = 0.020).

CONCLUSION

The new kidney allocation policy has led to an increase in KDPI of donors with longer cold ischemia time, leading to higher delayed graft function rates. This has resulted in increasing logistical and financial burdens on the system. Implementing large-scale changes in allocation based predominantly on predictive modeling needs to be intensely reassessed during a longer follow up.

Kidney accelerated placement project: Outcomes and lessons learned

Opportunities continue to be lost with a high rate of kidneys recovered for transplant but not utilized, particularly those considered less than ideal quality. The Organ Procurement and Transplantation Network (OPTN) Organ Center is tasked with allocating arguably the most difficult-to-place kidneys, and we hypothesized an accelerated placement pathway would increase utilization of kidneys placed by the Organ Center. The Kidney Accelerated Placement (KAP) project, implemented by the Organ Center from July 18, 2019 to July 15, 2020, aimed to offer kidneys with a high kidney donor profile index to programs that had a history of accepting such organs. We compared OPTN kidney match run, donor, and transplant recipient data during the project period and 1 year prior. There was no statistically significant change in the percentage of KAP-eligible donors accepted during the project period (16.4%) compared to the prior year (17.5%). Conversion from acceptance to transplant was higher under KAP (72.7% vs. 71.2%), though not significant. Waiting to accelerate placement after kidneys have been declined by multiple transplant programs locally and regionally is an intervention that may come too late to effectively increase utilization. Transplant rates of nationally shared and marginal kidneys remain a challenge, and future iterations of this project should be investigated.

Number of Donor Renal Arteries and Early Outcomes after Deceased Donor Kidney Transplantation

Background

Anatomic abnormalities increase the risk of deceased donor kidney discard, but their effect on transplant outcomes is understudied. We sought to determine the effect of multiple donor renal arteries on early outcomes after deceased donor kidney transplantation.

Methods

For this retrospective cohort study, we identified 1443 kidneys from 832 deceased donors with ≥1 kidney transplanted at our center (2006-2016). We compared the odds of delayed graft function and 90-day graft failure using logistic regression. To reduce potential selection bias, we then repeated the analysis using a paired-kidney cohort, including kidney pairs from 162 donors with one single-artery kidney and one multiartery kidney.

Results

Of 1443 kidneys included, 319 (22%) had multiple arteries. Multiartery kidneys experienced longer cold ischemia time, but other characteristics were similar between groups. Delayed graft function (50% multiartery versus 45% one artery, P=0.07) and 90-day graft failure (3% versus 3%, P=0.83) were similar between groups before and after adjusting for donor and recipient characteristics. In the paired kidney analysis, cold ischemia time was significantly longer for multiartery kidneys compared with single-artery kidneys from the same donor (33.5 versus 26.1 hours, P<0.001), but delayed graft function and 90-day graft failure were again similar between groups.

Conclusions

Compared with single-artery deceased donor kidneys, those with multiple renal arteries are harder to place, but experience similar delayed graft function and early graft failure.