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The Effect of Acuity Circles on Deceased Donor Transplant and Offer Rates Across Model for End-Stage Liver Disease Scores and Exception Statuses

Wey, Andrew; Noreen, Samantha; Gentry, Sommer; Cafarella, Matt; Trotter, James; Salkowski, Nicholas; Segev, Dorry; Israni, Ajay; Kasiske, Bertram; Hirose, Ryutaro; Snyder, Jon
Acuity circles (AC), the new liver allocation system, was implemented on February 4, 2020. Difference-in-differences analyses estimated the effect of AC on adjusted deceased donor transplant and offer rates across Pediatric End-Stage Liver Disease (PELD) and Model for End-Stage Liver Disease (MELD) categories and types of exception statuses. The offer rates were the number of first offers, top 5 offers, and top 10 offers on the match run per person-year. Each analysis adjusted for candidate characteristics and only used active candidate time on the waiting list. The before-AC period was February 4, 2019, to February 3, 2020, and the after-AC period was February 4, 2020, to February 3, 2021. Candidates with PELD/MELD scores 29 to 32 and PELD/MELD scores 33 to 36 had higher transplant rates than candidates with PELD/MELD scores 15 to 28 after AC compared with before AC (transplant rate ratios: PELD/MELD scores 29-32, 2.34 3.324.71 ; PELD/MELD scores 33-36, 1.70 2.513.71 ). Candidates with PELD/MELD scores 29 or higher had higher offer rates than candidates with PELD/MELD scores 15 to 28, and candidates with PELD/MELD scores 29 to 32 had the largest difference (offer rate ratios [ORR]: first offers, 2.77 3.955.63 ; top 5 offers, 3.90 4.394.95 ; top 10 offers, 4.85 5.305.80 ). Candidates with exceptions had lower offer rates than candidates without exceptions for offers in the top 5 (ORR: hepatocellular carcinoma [HCC], 0.68 0.770.88 ; non-HCC, 0.73 0.810.89 ) and top 10 (ORR: HCC, 0.59 0.650.71 ; non-HCC, 0.69 0.750.81 ). Recipients with PELD/MELD scores 15 to 28 and an HCC exception received a larger proportion of donation after circulatory death (DCD) donors after AC than before AC, although the differences in the liver donor risk index were comparatively small. Thus, candidates with PELD/MELD scores 29 to 34 and no exceptions had better access to transplant after AC, and donor quality did not notably change beyond the proportion of DCD donors.
PMID: 34482614
ISSN: 1527-6473
CID: 5127612

Life expectancy without a transplant for status 1A liver transplant candidates

Wood, Nicholas L; VanDerwerken, Douglas N; King, Elizabeth A; Segev, Dorry L; Gentry, Sommer E
Status 1A liver transplant candidates are given the highest medical priority for the allocation of deceased donor livers. Organ Procurement and Transplantation Network (OPTN) policy requires physicians to certify that a candidate has a life expectancy without a transplant of less than 7 days for that candidate to be given status 1A. Additionally, candidates receiving status 1A must have one of six medical conditions listed in policy. Using Scientific Registry of Transplant Recipients data from all prevalent liver transplant candidates from 2010 to 2020, we used a bias-corrected Kaplan-Meier model to calculate the survival of status 1A candidates and to determine their life expectancy without a transplant. We found that status 1A candidates have a life expectancy without a transplant of 24 (95% CI 20-46) days-over three times longer than what policy requires for status 1A designation. We repeated the analysis for subgroups of status 1A candidates based on the medical conditions that grant status 1A. We found that none of these subgroups met the life expectancy requirement. Harmonizing OPTN policy with observed data would sustain the integrity of the allocation process.
PMID: 34487636
ISSN: 1600-6143
CID: 5127622

Designing Continuous Distribution for Liver Allocation [Meeting Abstract]

Mankowski, Michal; Wood, Nicholas; Segev, Dorry; Gentry, Sommer
ISSN: 1600-6135
CID: 5133502

Does MELD-GRAIL-Na Correct Racial Disparities In Survival Without A Liver Transplant? [Meeting Abstract]

VanDerwerken, Doug; Wood, Nicholas; Segev, Dorry; Gentry, Sommer
ISSN: 1600-6135
CID: 5133582

Characterizing the early impact of the Kidney Accelerated Placement Project on hard-to-place kidneys [Meeting Abstract]

Motter, Jennifer; Kernodle, Amber; Gentry, Sommer; Levan, Macey; Wood, Nicholas; Segev, Dorry; Garonzik-Wang, Jacqueline; Massie, Allan
ISSN: 1600-6135
CID: 5133672

Increased Logistical Complexity In Circle-Based Organ Allocation [Meeting Abstract]

Wood, Nicholas; VanDerwerken, Douglas; Segev, Dorry; Gentry, Sommer
ISSN: 1600-6135
CID: 5133692

Opportunities for Improved Efficiency in Kidney Distribution: A Comparison of Center-Specified UNet Donor Criteria to Actual Kidney Acceptance Practices [Meeting Abstract]

Zeiser, Laura; Gentry, Sommer; Segev, Dorry; Massie, Allan
ISSN: 1600-6135
CID: 5133702

MELD 3.0: The Model for End-Stage Liver Disease Updated for the Modern Era

Kim, W Ray; Mannalithara, Ajitha; Heimbach, Julie K; Kamath, Patrick S; Asrani, Sumeet K; Biggins, Scott W; Wood, Nicholas L; Gentry, Sommer E; Kwong, Allison J
BACKGROUND & AIMS:The Model for End-Stage Liver Disease (MELD) has been established as a reliable indicator of short-term survival in patients with end-stage liver disease. The current version (MELDNa), consisting of the international normalized ratio and serum bilirubin, creatinine, and sodium, has been used to determine organ allocation priorities for liver transplantation in the United States. The objective was to optimize MELD further by taking into account additional variables and updating coefficients with contemporary data. METHODS:All candidates registered on the liver transplant wait list in the US national registry from January 2016 through December 2018 were included. Uni- and multivariable Cox models were developed to predict survival up to 90 days after wait list registration. Model fit was tested using the concordance statistic (C-statistic) and reclassification, and the Liver Simulated Allocation Model was used to estimate the impact of replacing MELDNa with the new model. RESULTS:The final multivariable model was characterized by (1) additional variables of female sex and serum albumin, (2) interactions between bilirubin and sodium and between albumin and creatinine, and (3) an upper bound for creatinine at 3.0 mg/dL. The final model (MELD 3.0) had better discrimination than MELDNa (C-statistic, 0.869 vs 0.862; P < .01). Importantly, MELD 3.0 correctly reclassified a net of 8.8% of decedents to a higher MELD tier, affording them a meaningfully higher chance of transplantation, particularly in women. In the Liver Simulated Allocation Model analysis, MELD 3.0 resulted in fewer wait list deaths compared to MELDNa (7788 vs 7850; P = .02). CONCLUSION:MELD 3.0 affords more accurate mortality prediction in general than MELDNa and addresses determinants of wait list outcomes, including the sex disparity.
PMID: 34481845
ISSN: 1528-0012
CID: 5139432

Correcting the sex disparity in MELD-Na

Wood, Nicholas L; VanDerwerken, Douglas; Segev, Dorry L; Gentry, Sommer E
MELD-Na appears to disadvantage women awaiting liver transplant by underestimating their mortality rate. Fixing this problem involves: (1) estimating the magnitude of this disadvantage separately for each MELD-Na, (2) designing a correction for each MELD-Na, and (3) evaluating corrections to MELD-Na using simulated allocation. Using Kaplan-Meier modeling, we calculated 90-day without-transplant survival for men and women, separately at each MELD-Na. For most scores between 15 and 35, without-transplant survival was higher for men by 0-5 percentage points. We tested two proposed corrections to MELD-Na (MELD-Na-MDRD and MELD-GRAIL-Na), and one correction we developed (MELD-Na-Shift) to target the differences we quantified in survival across the MELD-Na spectrum. In terms of without-transplant survival, MELD-Na-MDRD overcorrected sex differences while MELD-GRAIL-Na and MELD-Na-Shift eliminated them. Estimating the impact of implementing these corrections with the liver simulated allocation model, we found that MELD-Na-Shift alone eliminated sex disparity in transplant rates (p = 0.4044) and mortality rates (p = 0.7070); transplant rates and mortality rates were overcorrected by MELD-Na-MDRD (p = 0.0025, p = 0.0006) and MELD-GRAIL-Na (p = 0.0079, p = 0.0005). We designed a corrected MELD-Na that eliminates sex disparities in without-transplant survival, but allocation changes directing smaller livers to shorter candidates may also be needed to equalize women's access to liver transplant.
PMID: 34174151
ISSN: 1600-6143
CID: 5127342

MELD is MELD is MELD? Transplant center-level variation in waitlist mortality for candidates with the same biological MELD

Ishaque, Tanveen; Kernodle, Amber B; Motter, Jennifer D; Jackson, Kyle R; Chiang, Teresa P; Getsin, Samantha; Boyarsky, Brian J; Garonzik-Wang, Jacqueline; Gentry, Sommer E; Segev, Dorry L; Massie, Allan B
Recently, model for end-stage liver disease (MELD)-based liver allocation in the United States has been questioned based on concerns that waitlist mortality for a given biologic MELD (bMELD), calculated using laboratory values alone, might be higher at certain centers in certain locations across the country. Therefore, we aimed to quantify the center-level variation in bMELD-predicted mortality risk. Using Scientific Registry of Transplant Recipients (SRTR) data from January 2015 to December 2019, we modeled mortality risk in 33 260 adult, first-time waitlisted candidates from 120 centers using multilevel Poisson regression, adjusting for sex, and time-varying age and bMELD. We calculated a "MELD correction factor" using each center's random intercept and bMELD coefficient. A MELD correction factor of +1 means that center's candidates have a higher-than-average bMELD-predicted mortality risk equivalent to 1 bMELD point. We found that the "MELD correction factor" median (IQR) was 0.03 (-0.47, 0.52), indicating almost no center-level variation. The number of centers with "MELD correction factors" within ±0.5 points, and between ±0.5-± 1, ±1.0-±1.5, and ±1.5-±2.0 points was 62, 41, 13, and 4, respectively. No centers had waitlisted candidates with a higher-than-average bMELD-predicted mortality risk beyond ±2 bMELD points. Given that bMELD similarly predicts waitlist mortality at centers across the country, our results support continued MELD-based prioritization of waitlisted candidates irrespective of center.
PMID: 33870635
ISSN: 1600-6143
CID: 5127132