Perioperative mortality in liver transplantation before and after the implementation of the organ allocation policy Share 35.

INTRODUCTION: In 2013, a new liver transplant allocation policy (Share 35) aimed to reduce waitlist-mortality was introduced in the United States. Regional organ sharing for recipients with a MELD score of ≥35 was prioritized over local allocation to those with lower MELD scores. Our aim was to assess the changes in perioperative mortality following the introduction of Share 35 as well as changes in patients' short-term 7-day survival, patients discharged alive and 1-year survival. Analyses were also carried out for the subgroups of patients with MELD scores ≥ and < 35. METHODS: We used data from the Scientific Registry of Transplant Recipients and included liver transplants between March 2002 and December 2018 in this retrospective cohort study. Perioperative mortality was defined as death during and within two days of liver transplant. We used robust interrupted time series analyses to evaluate the impact of Share 35 on mortality. RESULTS: We included 90 002 liver transplants in our analysis and observed a decreasing trend in perioperative mortality over time (-.061 deaths per 1000 cases per month, 95% CI -.084 to -.037, p < .001). Share 35 was not associated with a change in perioperative mortality (p = .33), short-term 7-day survival (p = .48), survival to discharge (p = .56), or 1-year survival (p = .27). CONCLUSIONS: Prioritizing sicker recipients with a MELD score ≥35 for liver transplantation was not associated with a change in postoperative mortality.

Awarding additional MELD points to the shortest waitlist candidates improves sex disparity in access to liver transplant in the United States.

Since the introduction of the MELD-based allocation system, women are now 30% less likely than men to undergo liver transplant (LT) and have 20% higher waitlist mortality. These disparities are in large part due to height differences in men and women though no national policies have been implemented to reduce sex disparities. Patients were identified using the Scientific Registry of Transplant Recipients (SRTR) from 2014 to 2019. Patients were categorized into five groups by first dividing into thirds by height then dividing the shortest third into three groups to capture more granular differences in the most disadvantaged patients (<166 cm). We then used LSAM to model waitlist outcomes in five versions of awarding additional MELD points to shorter candidates compared to current policy. We identified two proposed policy changes LSAM scenarios that resulted in improvement in LT and death percentage for the shortest candidates with the least negative impact on taller candidates. In conclusion, awarding an additional 1-2 MELD points to the shortest 8% of LT candidates would improve waitlist outcomes for women. This strategy should be considered in national policy allocation to address sex-based disparities in LT.

Correcting the sex disparity in MELD-Na.

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.

The decreasing predictive power of MELD in an era of changing etiology of liver disease.

The field of liver transplantation has shifted considerably in the MELD era, including changing allocation, immunosuppression, and liver failure etiologies, as well as better supportive therapies. Our aim was to evaluate the predictive accuracy of the MELD score over time. The United Network for Organ Sharing provided de-identified data on 120 156 patients listed for liver transplant from 2002-2016. The ability of the MELD score to predict 90-day mortality was evaluated by a concordance (C-) statistic and corroborated with competing risk analysis. The MELD score's concordance with 90-day mortality has downtrended from 0.80 in 2003 to 0.70 in 2015. While lab MELD scores at listing and transplant climbed in that interval, score at waitlist death remained steady near 35. Listing age increased from 50 to 54 years. HCV-positive status at listing dropped from 33 to 17%. The concordance of MELD and mortality does not differ with age (>60 = 0.73, <60 = 0.74), but is lower in diseases that are increasing most rapidly-alcoholic liver disease and non-alcoholic fatty liver disease-and higher in those that are declining, particularly in HCV-positive patients (HCV positive = 0.77; negative = 0.73). While MELD still predicts mortality, its accuracy has decreased; changing etiology of disease may contribute.

Mortality Risk Factors Among Patients With Cirrhosis and a Low Model for End-Stage Liver Disease Sodium Score (≤15): An Analysis of Liver Transplant Allocation Policy Using Aggregated Electronic Health Record Data.

Although the Model for End-Stage Liver Disease sodium (MELD Na) score is now used for liver transplant allocation in the United States, mortality prediction may be underestimated by the score. Using aggregated electronic health record data from 7834 adult patients with cirrhosis, we determined whether the cause of cirrhosis or cirrhosis complications was associated with an increased risk of death among patients with a MELD Na score ≤15 and whether patients with the greatest risk of death could benefit from liver transplantation (LT). Over median follow-up of 2.3 years, 3715 patients had a maximum MELD Na score ≤15. Overall, 3.4% were waitlisted for LT. Severe hypoalbuminemia, hepatorenal syndrome, and hepatic hydrothorax conferred the greatest risk of death independent of MELD Na score with 1-year predicted mortality >14%. Approximately 10% possessed these risk factors. Of these high-risk patients, only 4% were waitlisted for LT, despite no difference in nonliver comorbidities between waitlisted patients and those not listed. In addition, risk factors for death among waitlisted patients were the same as those for patients not waitlisted, although the effect of malnutrition was significantly greater for waitlisted patients (hazard ratio 8.65 [95% CI 2.57-29.11] vs. 1.47 [95% CI 1.08-1.98]). Using the MELD Na score for allocation may continue to limit access to LT.

National Outcomes of Liver Transplantation for Model for End-Stage Liver Disease Score ≥40: The Impact of Share 35.

In certain regions of the United States in which organ donor shortages are persistent and competition is high, recipients wait longer and are critically ill with Model for End-Stage Liver Disease (MELD) scores ≥40 when they undergo liver transplantation. Recent implementation of Share 35 has increased the percentage of recipients transplanted at these higher MELD scores. The purpose of our study was to examine national data of liver transplant recipients with MELD scores ≥40 and to identify risk factors that affect graft and recipient survival. During the 12-year study period, 5002 adult recipients underwent deceased donor whole-liver transplantation. The 1-, 3-, 5- and 10-year graft survival rates were 77%, 69%, 64% and 50%, respectively. The 1-, 3-, 5- and 10-year patient survival rates were 80%, 72%, 67% and 53%, respectively. Multivariable analysis identified previous transplant, ventilator dependence, diabetes, hepatitis C virus, age >60 years and prolonged hospitalization prior to transplant as recipient factors increasing the risk of graft failure and death. Donor age >30 years was associated with an incrementally increased risk of graft failure and death. Recipients after implementation of Share 35 had shorter waiting times and higher graft and patient survival compared with pre-Share 35 recipients, demonstrating that some risk factors can be mitigated by policy changes that increase organ accessibility.