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.

Impact of early biliary complications on long-term outcomes in adult-to-adult living donor liver transplant recipients

BACKGROUND

An adult-to-adult living donor liver transplant (LDLT) has emerged as a possible option to help alleviate the organ shortage. The aim of this study was to analyze our experience with biliary complications in LDLT recipients and to identify their risk factors for biliary complications. This paper aimed to describe therapeutic interventions and to evaluate the impact of biliary complications on long-term patient and graft survival rates.

METHODS

We evaluated biliary complications in a cohort of 120 LDLT recipients at a single institution and studied the impact on long-term graft and patient survival.

RESULTS

Of the 120 recipients, 26 (21.7%) developed biliary complications. Endoscopy was the initial choice of treatment for recipients with biliary complications. The median time for resolution of bile leaks was 37 days; for resolution of strictures, 82 days. A decreased risk of biliary complications was associated with an interrupted duct-to-duct (versus continuous choledocho-choledochostomy) (hazard ratio [HR]=0.22, P=0.002) and a Roux-en-Y hepaticojejunostomy (HR=0.13, P<0.001). In multivariate analysis of factors associated with graft failure and patient mortality, biliary complications were unrelated to long term (3 and 5 years) graft failure or patient mortality.

CONCLUSIONS

In our study LDLT recipients had a 21.7% incidence of biliary complications, however, with successful endoscopic techniques, long-term patient and graft survival rates were not negatively affected.

Phase II study of avatrombopag in thrombocytopenic patients with cirrhosis undergoing an elective procedure

BACKGROUND & AIMS

This is a phase II multicentre study to investigate the efficacy and safety of avatrombopag (E5501), an investigational second-generation thrombopoietin receptor agonist, administered one week prior to elective procedures in patients with thrombocytopenia secondary to cirrhosis.

METHODS

Adults with cirrhosis and platelet counts ⩾10 to ⩽58×10(9)/L were randomized to placebo or avatrombopag in two sequential cohorts. Cohort A: placebo vs. one of 3 different doses (100mg loading dose followed by 20, 40, or 80 mg/day on days 2-7) of a first-generation avatrombopag formulation. Cohort B: placebo vs. one of 2 different doses (80 mg loading dose followed by 10 mg/day for days 2-7, or 20mg/day for days 2-4) of a second-generation avatrombopag formulation. Primary end point was achievement of a platelet increase of ⩾20×10(9)/L from baseline and >50×10(9)/L at least once during days 4-8.

RESULTS

A total of 130 patients were randomized: 93 patients (51, cohort A; 42, cohort B) to avatrombopag and 37 (16, cohort A; 21 cohort B) to placebo. The primary end point was achieved by 49.0% of treated patients in cohort A and 47.6% in cohort B compared to 6.3% and 9.5% of controls; a dose response was seen. Each avatrombopag regimen had a higher proportion of responders compared with their respective cohort placebo arms (p<0.01), except for the 100/40 mg group in cohort A (p=0.17). The most common adverse events were nausea, fatigue, and headache. One patient in the (100/80) avatrombopag group, without a Doppler assessment at screening was diagnosed with portal vein thrombosis during post-treatment follow-up.

CONCLUSIONS

In this study avatrombopag was generally well-tolerated and increased platelet counts in patients with cirrhosis undergoing elective invasive procedures.

Solid-organ transplantation in older adults: current status and future research

An increasing number of patients older than 65 years are referred for and have access to organ transplantation, and an increasing number of older adults are donating organs. Although short-term outcomes are similar in older versus younger transplant recipients, older donor or recipient age is associated with inferior long-term outcomes. However, age is often a proxy for other factors that might predict poor outcomes more strongly and better identify patients at risk for adverse events. Approaches to transplantation in older adults vary across programs, but despite recent gains in access and the increased use of marginal organs, older patients remain less likely than other groups to receive a transplant, and those who do are highly selected. Moreover, few studies have addressed geriatric issues in transplant patient selection or management, or the implications on health span and disability when patients age to late life with a transplanted organ. This paper summarizes a recent trans-disciplinary workshop held by ASP, in collaboration with NHLBI, NIA, NIAID, NIDDK and AGS, to address issues related to kidney, liver, lung, or heart transplantation in older adults and to propose a research agenda in these areas.

Variation, precision and validity of 1-year survival estimates for lung, breast, colon and prostate cancer in South East England primary care trusts

BACKGROUND

English cancer policy has encouraged primary care trusts (PCTs) to consider their 1-year cancer survival estimates. This study quantifies variation in these estimates across 39 PCTs in the London and South East Coast strategic health authorities, and explores their precision, possible confounding by age and bias due to death certificate only (DCO) registrations.

STUDY DESIGN

Retrospective observational study.

METHODS

One-year relative survival estimates and data on DCO registrations for patients diagnosed with lung, colorectal, breast and prostate cancers between 2002 and 2006 were extracted from the UK Cancer Information Service. Direct age standardization was performed with weightings derived from the standard cancer patient population for Europe. Pearson correlation coefficients between survival estimates and DCO proportions were calculated.

RESULTS

Mean 1-year PCT survival estimates ranged from 6.9 to 19.4 percentage points, and the precision of individual estimates ranged from ±0.9 to ±6.5 percentage points (at 95% confidence level). Age standardization significantly changed the estimates of nine PCTs for breast cancer, five PCTs for lung cancer and three PCTs for colorectal cancer. None of the prostate cancer estimates were affected significantly. DCO proportions were positively associated with lung cancer survival and negatively associated with colorectal and breast cancer survival.

CONCLUSIONS

PCT 1-year cancer survival estimates may be informative, but caveats relating to data quality and hence the validity of the estimates means that they require careful investigation before naïve use, as random variation, confounding due to age and bias due to DCO registrations may be significant.

Piezoelectric Materials and Devices for Wind Energy Harvesting

We present materials development in fabricating thin film devices for the conversion of wind energy as a sustainable energy source. We demonstrate the feasibility of piezoelectric polymer thin film devices to harvest wind energy in a miniature wind tunnel. Using an example of prototype device based on polyvinylidene fluoride (PVDF) thin film devices, we are able to obtain electrical power from the wind’s energy through the mechanical deformation of PVDF, such as that obtained from the films flapping in the wind. We have obtained a preliminary result of 1 mW power (at 15 mph wind) with a single layer of PVDF of 4 x 2 inches and 50 μm in thickness sandwiched between two thin gold electrode films. Additionally, the fracturing of metallic electrodes over time from the induced strain of this application lead to the significance of examining carbon nanotubes as compliant electrodes offering better mechanical properties while maintaining necessary electrical properties.

Report of a national conference on liver allocation in patients with hepatocellular carcinoma in the United States

A national conference was held to better characterize the long-term outcomes of liver transplantation (LT) for patients with hepatocellular carcinoma (HCC) and to assess whether it is justified to continue the policy of assigning increased priority for candidates with early-stage HCC on the transplant waiting list in the United States. The objectives of the conference were to address specific HCC issues as they relate to liver allocation, develop a standardized pathology report form for the assessment of the explanted liver, develop more specific imaging criteria for HCC designed to qualify LT candidates for automatic Model for End-Stage Liver Disease (MELD) exception points without the need for biopsy, and develop a standardized pretransplant imaging report form for the assessment of patients with liver lesions. At the completion of the meeting, there was agreement that the allocation policy should result in similar risks of removal from the waiting list and similar transplant rates for HCC and non-HCC candidates. In addition, the allocation policy should select HCC candidates so that there are similar posttransplant outcomes for HCC and non-HCC recipients. There was a general consensus for the development of a calculated continuous HCC priority score for ranking HCC candidates on the list that would incorporate the calculated MELD score, alpha-fetoprotein, tumor size, and rate of tumor growth. Only candidates with at least stage T2 tumors would receive additional HCC priority points.

Graft weight/recipient weight ratio: how well does it predict outcome after partial liver transplants?

Partial graft liver recipients with graft weight/recipient weight (GW/RW) ratios < 0.8% are thought to have a higher incidence of postoperative complications, including small-for-size syndrome (SFSS). We analyzed a cohort of such recipients and compared those with GW/RW < 0.8% to those with GW/RW >or= 0.8%. Between 1999 and 2008, 107 adult patients underwent partial graft liver transplants: 76 from live donors [living donor liver transplantation (LDLT)] and 31 from deceased donors [split liver transplantation (SLT)]. Of these, 22 had GW/RW < 0.8% (12 with LDLT and 10 with SLT), and 85 had GW/RW >or= 0.8% (64 with LDLT and 21 with SLT). The baseline demographics and median length of follow-up were similar. SFSS developed in 3 recipients with GW/RW < 0.8% (13.6%) and in 8 recipients with GW/RW >or= 0.8% (9.4%; P = not significant). Other early complications were similar between the 2 groups. Inflow modification with splenic artery occlusion was performed in 13 recipients: 7 with GW/RW < 0.8% and 6 with GW/RW >or= 0.8%. Graft survival at 1 year post-transplant did not differ (91% versus 92%; P = not significant). In conclusion, GW/RW did not appear to be the only determinant of outcome after partial liver transplantation. Using techniques such as inflow modification may help to prevent some of the problems seen with smaller grafts.

Delayed splenic artery occlusion for treatment of established small-for-size syndrome after partial liver transplantation

We looked at the impact of delayed splenic artery occlusion (SAO) on recipients with established small-for-size syndrome (SFSS) after partial graft liver transplantation [either from a living donor (LD) or split from a deceased donor (DD)]. Between 1999 and 2007 we performed a total of 100 partial liver transplantations in adult recipients: 66 LD transplantations and 34 DD split transplantations. Of these, 7 (7%) developed SFSS, diagnosed by the clinical features of cholestasis, coagulopathy, and ascites. Mean graft weight/recipient weight (GW/RW) ratio in these 7 recipients was 0.94%. Five of these 7 recipients underwent relaparotomy at a mean of 10 days post-transplantation to rule out a technical complication, and then intraoperative splenic artery ligation was performed. The other 2 recipients were treated radiologically by splenic artery coiling-at 9 and 13 days post-transplantation. Median serum bilirubin at the time of the splenic artery procedure was 20 mg/dL; by 3 weeks postprocedure this had decreased to 2.5 mg/dL. Of the 7 recipients with SFSS, 6 improved and eventually obtained normal graft function; 1 recipient did not improve and ultimately underwent retransplantation because of persistent cholestasis and failure to thrive. Delayed SAO represents a potential option for the treatment of recipients with established SFSS after partial liver transplantation.

Prediction of clinical outcomes in primary biliary cirrhosis by serum enhanced liver fibrosis assay

Primary biliary cirrhosis (PBC) is sometimes diagnosed based on a positive antimitochondrial antibody in the appropriate clinical setting without a liver biopsy. Although a liver biopsy can assess the extent of liver fibrosis and provide prognostic information, serum fibrosis markers avoid biopsy complications and sampling error and provide results as a continuous variable, which may be more precise than categorical histological stages. The current study was undertaken to evaluate serum fibrosis markers as predictors of clinical progression in a large cohort of PBC patients. Serial liver biopsy specimens and serum samples were collected every 2 years in 161 PBC subjects for a median of 7.3 years. Clinical progression was defined as development of one or more of the following events: varices, variceal bleed, ascites, encephalopathy, liver transplantation, or liver-related death. Serum hyaluronic acid, tissue inhibitor of metalloproteinase 1, and procollagen III aminopeptide were measured and entered into the previously validated enhanced liver fibrosis (ELF) algorithm. The ability of ELF, histological fibrosis, bilirubin, Model for End-Stage Liver Disease (MELD), and Mayo Risk Score to differentiate between individuals who would experience a clinical event from those who would not was evaluated at different time points. Event-free survival was significantly lower in those with high baseline ELF. Each 1-point increase in ELF was associated with a threefold increase in future complications. The prognostic performance of all tests was similar when performed close to the time of the first event. However, at earlier times in the disease process (4 and 6 years before the first event), the prognostic performance of ELF was significantly better than MELD or Mayo R score.

CONCLUSION

The ELF algorithm is a highly accurate noninvasive measure of PBC disease severity that provides useful long-term prognostic information.