Exception point applications for 15 points: an unintended consequence of the share 15 policy

Creating synthetic populations in transplantation: A Bayesian approach enabling simulation without registry re-sampling

Computer simulation has played a pivotal role in analyzing alternative organ allocation strategies in transplantation. The current approach to producing cohorts of organ donors and candidates for individual-level simulation requires directly re-sampling retrospective data from a transplant registry. This historical data may reflect outmoded policies and practices as well as systemic inequities in candidate listing, limiting contemporary applicability of simulation results. We describe the development of an alternative approach for generating synthetic donors and candidates using hierarchical Bayesian network probability models. We developed two Bayesian networks to model dependencies among 10 donor and 36 candidate characteristics relevant to waitlist survival, donor-candidate matching, and post-transplant survival. We estimated parameters for each model using Scientific Registry of Transplant Recipients (SRTR) data. For 100 donor and 100 candidate synthetic populations generated, proportions for each categorical donor or candidate attribute, respectively, fell within one percentage point of observed values; the interquartile ranges (IQRs) of each continuous variable contained the corresponding SRTR observed median. Comparisons of synthetic to observed stratified distributions demonstrated the ability of the method to capture complex joint variability among multiple characteristics. We also demonstrated how changing two upstream population parameters can exert cascading effects on multiple relevant clinical variables in a synthetic population. Generating synthetic donor and candidate populations in transplant simulation may help overcome critical limitations related to the re-sampling of historical data, allowing developers and decision makers to customize the parameters of these populations to reflect realistic or hypothetical future states.

Current Approaches in the Allocation of Liver Transplantation

In recent decades, important advances have been made in the field of liver transplantation. One of the major problems remaining in this area is the small number of donors. Thus, recent data bring multiple updates of the indications and contraindications of this therapeutic method. The main goal is to increase the number of patients who can benefit from liver transplantation, a therapeutic method that can improve life expectancy and the quality of life of patients with end-stage liver disease. Another goal in the management of these patients is represented by the optimal care of those on the waiting list during that period. A multidisciplinary team approach is necessary to obtain the best results for both the donor and the recipient.

Survival After Liver Transplantation: An International Comparison Between the United States and the United Kingdom in the Years 2008-2016

BACKGROUND

Compared with the United States, risk-adjusted mortality in the United Kingdom has historically been worse in the first 90 d following liver transplantation (LT) and better thereafter. In the last decade, there has been considerable change in the practice of LT internationally, but no contemporary large-scale international comparison of posttransplant outcomes has been conducted. This study aimed to determine disease-specific short- and long-term mortality of LT recipients in the United States and the United Kingdom.

METHODS

This retrospective international multicenter cohort study analyzed adult (≥18 y) first-time LT recipients between January 2, 2008, and December 31, 2016, using the Organ Procurement and Transplantation Network/United Network for Organ Sharing and the UK Transplant Registry databases. Time-dependent Cox regression estimated hazard ratios (HRs) comparing disease-specific risk-adjusted mortality in the first 90 d post-LT, between 90 d and 1 y, and between 1 and 5 y.

RESULTS

Forty-two thousand eight hundred seventy-four US and 4950 UK LT recipients were included. The main LT indications in the United States and the United Kingdom were hepatocellular carcinoma (25.4% and 24.9%, respectively) and alcohol-related liver disease (20.3% and 27.1%, respectively). There were no differences in mortality during the first 90 d post-LT (reference: United States; HR, 0.96; 95% confidence interval [CI], 0.82-1.12). However, between 90 d and 1 y (HR, 0.71; 95% CI, 0.59-0.85) and 1 and 5 y (HR, 0.71; 95% CI, 0.63-0.81]) the United Kingdom had lower mortality. The mortality differences between 1 and 5 y were most marked in hepatocellular carcinoma (HR, 0.71; 95% CI, 0.58-0.88) and alcohol-related liver disease patients (HR, 0.64; 95% CI, 0.45-0.89).

CONCLUSIONS

Risk-adjusted mortality in the United States and the United Kingdom was similar in the first 90 d post-LT but better in the United Kingdom thereafter. International comparisons of LT may highlight differences in healthcare delivery and help benchmarking by identifying modifiable factors that can facilitate improved global outcomes in LT.

Low Health Literacy Is Associated With Frailty and Reduced Likelihood of Liver Transplant Listing: A Prospective Cohort Study

The effect of low health literacy (HL) on outcomes in end-stage liver disease (ESLD) is largely unknown. The association of low HL on clinical outcomes was investigated in a prospective cohort of outpatients with ESLD undergoing liver transplantation (LT) evaluation. From 2014 to 2017, 276 patients underwent LT evaluation with assessments of liver disease severity, medical and psychosocial comorbidities, physical frailty, and malnutrition. Literacy was measured with the Newest Vital Sign, a brief validated assessment. Multivariate models assessed relationships between HL and clinical outcomes adjusting for clinical and psychosocial variables. The median Model for End-Stage Liver Disease-sodium score of the study sample was 15 (interquartile range, 11-19), 71 (25.7%) of candidates were frail, 117 (42.4%) had malnutrition, 151 (54.7%) had hepatic encephalopathy, 104 (37.7%) had low HL, and 85 (39.2%) had marginal or poor social support. Adjusting for education level, socioeconomic factors, and severity of illness, low HL was independently associated with physical frailty (adjusted odds ratio [aOR], 3.59; 95% confidence interval [CI], 1.50-8.59; P = 0.004) and not being wait-listed (aOR 1.96; 95% CI, 1.03-3.75; P = 0.04). Strong social support attenuated the relationship between low HL and not being wait-listed (aOR, 1.58; 95% CI, 0.74-3.36; P = 0.24). Low HL is common and a largely unrecognized risk factor for poor health outcomes among patients with ESLD. Patient-oriented infrastructure and support are needed at the health system level to ensure all patients can successfully navigate the complex process of LT evaluation and wait-listing.

Liver Transplantation for Hepatic Epithelioid Hemangioendothelioma Is Facilitated by Exception Points With Acceptable Long-term Outcomes

BACKGROUND

Hepatic epithelioid hemangioendothelioma (HEHE) is a rare vascular tumor with a high mortality rate. HEHE is now a formally recognized indication for exception point priority in the United States under the new National Liver Review Board. The role of liver transplantation (LT) and exception point waitlist priority in the United States for patients with HEHE remains understudied.

METHODS

This was a retrospective cohort study using the United Network for Organ Sharing transplant database. From February 27, 2002 to January 31, 2018, 131 adults waitlisted for LT with HEHE were identified by free-text entry.

RESULTS

Exception point applications were submitted for 91.6% (120/131) of patients. All patients with fully reviewed applications received exception points at least once during waitlisting, and 85% (103/120) upon first submission. Among the 88 patients transplanted, median model for end-stage liver disease score at LT was 7 ((interquartile range [IQR]: 6-11) and waiting time 78.5 days (IQR: 29.5-237.5). Unadjusted post-LT survival of HEHE recipients at 1-, 3-, and 5-years from LT was 88.6%, 78.9%, and 77.2%. Unadjusted post-LT patient and graft survival of HEHE patients was not different from patients with hepatocellular carcinoma within Milan receiving exception point priority (P = 0.08). An increased rate of graft failure due to hepatic artery thrombosis ≤14 days from initial LT was observed in HEHE versus non-HEHE patients (4.6% versus 0.5%).

CONCLUSIONS

The majority of HEHE recipients receive exception points at a universal approval rate allowing prompt access to deceased donor LT.

Outcomes of Liver Transplant Recipients With Model for End-Stage Liver Disease Exception: Single-Center Experience in the Northeast of Brazil

The Model for End-Stage Liver Disease (MELD) exception policy in liver transplantation is based on symptoms and clinical conditions not included in the calculated MELD score. Therefore, patients with chronic liver disease, like refractory ascites, chronic encephalopathy, recurrent cholangitis, and refractory pruritus, may benefit with extra points. The objective of this study was to establish the profile of the patients submitted to liver transplantation with MELD exceptions based on symptoms in the University Hospital Walter Cantídio, Ceara, Brazil, between the years of 2012 and 2015, analyzing donor and recipient data, with special attention to patients with refractory ascites and recurrent encephalopathy, including survival rates. The results demonstrated acceptable survival rates for MELD exception patients (78.4% in 3 years), showing that maybe this allocation criterion should be maintained, or even expanded.

Same policy, different impact: Center-level effects of share 35 liver allocation

Early studies of national data suggest that the Share 35 allocation policy increased liver transplants without compromising posttransplant outcomes. Changes in center-specific volumes and practice patterns in response to the national policy change are not well characterized. Understanding center-level responses to Share 35 is crucial for optimizing the policy and constructing effective future policy revisions. Data from the United Network for Organ Sharing were analyzed to compare center-level volumes of allocation-Model for End-Stage Liver Disease (aMELD) ≥ 35 transplants before and after policy implementation. There was significant center-level variation in the number and proportion of aMELD ≥ 35 transplants performed from the pre- to post-Share 35 period; 8 centers accounted for 33.7% of the total national increase in aMELD ≥ 35 transplants performed in the 2.5-year post-Share 35 period, whereas 25 centers accounted for 65.0% of the national increase. This trend correlated with increased listing at these centers of patients with Model for End-Stage Liver Disease (MELD) ≥ 35 at the time of initial listing. These centers did not overrepresent the total national volume of liver transplants. Comparison of post-Share 35 aMELD to calculated time-of-transplant (TOT) laboratory MELD scores showed that only 69.6% of patients transplanted with aMELD ≥ 35 maintained a calculated laboratory MELD ≥ 35 at the TOT. In conclusion, Share 35 increased transplantation of aMELD ≥ 35 recipients on a national level, but the policy asymmetrically impacted practice patterns and volumes of a subset of centers. Longer-term data are necessary to assess outcomes at centers with markedly increased volumes of high-MELD transplants after Share 35. Liver Transplantation 23 741-750 2017 AASLD.

Current Status of Liver Allocation in the United States

The liver transplant allocation system is currently based upon the Model for End-Stage Liver Disease (MELD) score and allocates organs preferentially to patients with the highest scores (ie, the sickest patients) within a defined geographic unit. In addition, certain patient populations, such as patients with hepatocellular carcinoma and portopulmonary hypertension, receive MELD exception points to account for their increased waitlist mortality, which is not reflected by their MELD score. Significant geographic variation in the access to liver transplantation exists throughout the United States. Both the Organ Procurement and Transplant Network Board of Directors and the Health Resources and Services Administration have determined these geographic disparities to be unacceptable. The liver transplant community has worked to develop methods to reduce these geographic disparities and to reexamine how MELD exception points are granted to certain patient populations. As a result, numerous policy changes have been adopted throughout the years that have broadened the sharing of organs through wider geographic sharing. Despite all of these changes, variation in access to liver transplantation continues to exist, and, thus, the liver transplant community continues to examine new ways to address geographic disparities. This paper reviews several of the key changes to the liver allocation system that have occurred since the implementation of MELD allocation in 2002 and provides an overview of potential changes to the system.

Financial Impact of Liver Sharing and Organ Procurement Organizations' Experience With Share 35: Implications for National Broader Sharing

The Share 35 policy for organ allocation, which was adopted in June 2013, allocates livers regionally for candidates with Model for End-Stage Liver Disease scores of 35 or greater. The authors analyzed the costs resulting from the increased movement of allografts related to this new policy. Using a sample of nine organ procurement organizations, representing 17% of the US population and 19% of the deceased donors in 2013, data were obtained on import and export costs before Share 35 implementation (June 15, 2012, to June 14, 2013) and after Share 35 implementation (June 15, 2013, to June 14, 2014). Results showed that liver import rates increased 42%, with an increased cost of 51%, while export rates increased 112%, with an increased cost of 127%. When the costs of importing and exporting allografts were combined, the total change in costs for all nine organ procurement organizations was $11 011 321 after Share 35 implementation. Extrapolating these costs nationally resulted in an increased yearly cost of $68 820 756 by population or $55 056 605 by number of organ donors. Any alternative allocation proposal needs to account for the financial implications to the transplant infrastructure.

Early changes in liver distribution following implementation of Share 35

In June 2013, a change to the liver waitlist priority algorithm was implemented. Under Share 35, regional candidates with MELD ≥ 35 receive higher priority than local candidates with MELD < 35. We compared liver distribution and mortality in the first 12 months of Share 35 to an equivalent time period before. Under Share 35, new listings with MELD ≥ 35 increased slightly from 752 (9.2% of listings) to 820 (9.7%, p = 0.3), but the proportion of deceased-donor liver transplants (DDLTs) allocated to recipients with MELD ≥ 35 increased from 23.1% to 30.1% (p < 0.001). The proportion of regional shares increased from 18.9% to 30.4% (p < 0.001). Sharing of exports was less clustered among a handful of centers (Gini coefficient decreased from 0.49 to 0.34), but there was no evidence of change in CIT (p = 0.8). Total adult DDLT volume increased from 4133 to 4369, and adjusted odds of discard decreased by 14% (p = 0.03). Waitlist mortality decreased by 30% among patients with baseline MELD > 30 (SHR = 0.70, p < 0.001) with no change for patients with lower baseline MELD (p = 0.9). Posttransplant length-of-stay (p = 0.2) and posttransplant mortality (p = 0.9) remained unchanged. In the first 12 months, Share 35 was associated with more transplants, fewer discards, and lower waitlist mortality, but not at the expense of CIT or early posttransplant outcomes.

Standardizing MELD Exceptions: Current Challenges and Future Directions

Since MELD-based allocation was implemented in 2002, a system of exception points has been in place in order to award increased waitlist priority to those patients whose severity of illness or risk of complications are not captured by the MELD score. These exceptions, categorized as standardized and non-standardized, have been used with increasing frequency over time. Several challenges to the exception point system have emerged, including lack of standardization in the criteria used to approve such exceptions, geographic variability in the use and approval of such exceptions, and limited evidence base to support certain exceptions. Herein, we summarize the current implementation of exception points, the challenges facing the transplant community, and suggestions for improving and standardizing the current exception point system.

Evolving trends in liver transplantation: listing and liver donor allocation

The success of liver transplantation in the past three decades as a life-saving procedure for patients with end-stage liver disease has led to the ever-increasing disparity between the demands for liver transplantation and the supply of donor liver organs. Donor allocation and distribution remains a challenge and a moral issue as to how these organs can be equitably distributed. This article reviews the evolution of the liver allocation policy and discusses in detail the challenges clinicians face today in this area of medicine.

Association of distance from a transplant center with access to waitlist placement, receipt of liver transplantation, and survival among US veterans

IMPORTANCE

Centralization of specialized health care services such as organ transplantation and bariatric surgery is advocated to improve quality, increase efficiency, and reduce cost. The effect of increased travel on access and outcomes from these services is not fully understood.

OBJECTIVE

To evaluate the association between distance from a Veterans Affairs (VA) transplant center (VATC) and access to being waitlisted for liver transplantation, actually having a liver transplant, and mortality.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective study of veterans meeting liver transplantation eligibility criteria from January 1, 2003, until December 31, 2010, using data from the Veterans Health Administration's integrated, national, electronic medical record linked to Organ Procurement and Transplantation Network data.

MAIN OUTCOMES AND MEASURES

The primary outcome was being waitlisted for transplantation at a VATC. Secondary outcomes included being waitlisted at any transplant center, undergoing a transplantation, and survival.

RESULTS

From 2003-2010, 50,637 veterans were classified as potentially eligible for transplant; 2895 (6%) were waitlisted and 1418 of those were waitlisted (49%) at 1 of the 5 VATCs. Of 3417 veterans receiving care at a VA hospital located within 100 miles from a VATC, 244 (7.1%) were waitlisted at a VATC and 372 (10.9%) at any transplant center (VATC and non-VATCs). Of 47,219 veterans receiving care at a VA hospital located more than 100 miles from a VATC, 1174 (2.5%) were waitlisted at a VATC and 2523 (5.3%) at any transplant center (VATC and non-VATCs). In multivariable models, increasing distance to closest VATC was associated with significantly lower odds of being waitlisted at a VATC (odds ratio [OR], 0.91 [95% CI, 0.89-0.93] for each doubling in distance) or any transplant center (OR, 0.94 [95% CI, 0.92-0.96] for each doubling in distance). For example, a veteran living 25 miles from a VATC would have a 7.4% (95% CI, 6.6%-8.1%) adjusted probability of being waitlisted, whereas a veteran 100 miles from a VATC would have a 6.2% (95% CI, 5.7%-6.6%) adjusted probability. In adjusted models, increasing distance from a VATC was associated with significantly lower transplantation rates (subhazard ratio, 0.97; 95% CI, 0.95-0.98 for each doubling in distance). There was significantly increased mortality among waitlisted veterans from the time of first hepatic decompensation event in multivariable survival models (hazard ratio, 1.03; 95% CI, 1.01-1.04 for each doubling in distance). For example, a waitlisted veteran living 25 miles from a VATC would have a 62.9% (95% CI, 59.1%-66.1%) 5-year adjusted probability of survival from first hepatic decompensation event compared with a 59.8% (95% CI, 56.3%-63.1%) 5-year adjusted probability of survival for a veteran living 100 miles from a VATC.

CONCLUSIONS AND RELEVANCE

Among VA patients meeting eligibility criteria for liver transplantation, greater distance from a VATC or any transplant center was associated with lower likelihood of being waitlisted, receiving a liver transplant, and greater likelihood of death. The relationship between these findings and centralizing specialized care deserves further investigation.

Center variation in the use of nonstandardized model for end-stage liver disease exception points

The Model for End-Stage Liver Disease (MELD) score is an imperfect prognosticator of waitlist dropout, so transplant centers may apply for exception points to increase a waitlist candidate's priority on the waitlist. Exception applications are categorized as recognized exceptional diagnoses (REDs; eg, hepatocellular carcinoma) and non-REDs (eg, cholangitis). Although prior work has demonstrated regional variation in the use of exceptions, no work has examined the between-center variability. We analyzed all new waitlist candidates from February 27, 2002 to June 3, 2011 to explore variations in the use of non-REDs, for which no strict exception criteria exist. There were 58,641 new waitlist candidates, and 4356 (7.4%) applied for a non-RED exception. The number of applications increased steadily over time, as did the approval rates for such applications: from <50% in 2002 to nearly 75% in 2010. When we adjusted for patient factors, there was significant variability (P < 0.001) in the use of non-RED exceptions in 8 of 11 United Network for Organ Sharing (UNOS) regions and in the approval of these exceptions in 6 of 11 UNOS regions. The variability in the use and approval of non-REDs was clinically significant: waitlist candidates with approved exceptions were significantly more likely to undergo transplantation (68.3% versus 53.4%, P < 0.001) and were less likely to be removed for death or clinical deterioration (10.4% versus 16.2%, P < 0.001). Increased median MELD score at transplantation within a donor service area was the only center factor associated with increased odds of applying for exceptions, while no center factors were associated with having non-RED exceptions approved. Further work is needed to identify other sources of variation to ensure the appropriate and equitable use of non-RED exceptions.