Liver redistricting: what are the upcoming changes in liver allocation in the United States?

Geographic disparity in liver transplantation is substantial in the United States, and primarily a byproduct of artificially created zones of organ distribution. In 2016, the United Network for Organ Sharing (UNOS) put forward a formal redistricting proposal with the goal of reducing this variability by regrouping the country's 58 donation service areas into eight new districts. This review provides a summary of the redistricting proposal's methodologies, expected results, criticisms and next steps. Previous authors have extensively evaluated the limitations of the current organ allocation and distribution system and how inequities in access to liver transplantation occur. However, few have suggested or simulated new ways to solve or improve this process. The 2016 UNOS redistricting proposal constitutes the first formal evaluation of a novel distribution model. This proposal and its shortcomings have led to multiple discussions throughout the transplant community and encouraged further research in this field. This review provides an updated perspective on the key organ distribution issues facing the US transplant community at large, and how UNOS and other experts suggest the problem of geographic disparity in liver transplantation should be solved

Quantifying the Effect of Transplanting Older Donor Livers Into Younger Recipients: The Need for Donor-recipient Age Matching

Background. Increasing recipient and donor age are independently associated with survival after liver transplantation (LT). Whether donor age differentially impacts post-LToutcomes based on recipient age is unknown. Methods. This was a retrospective cohort study using Organ Procurement and Transplantation Network data. All adult deceased-donor, single organ, primary LTs from 2002 to 2015 were included. Donor and recipient age were categorized as younger than 40 years, 40 to 59 years, and 60 years or older. Mixed-effects survival analysis evaluated the risk of graft failure and death according to the interaction of donor and recipient age categories. Results. Of 63628 LTs, 6.6% were in recipients younger than 40 years, of which 51.4% used an age-matched donor younger than 40 years. There was a significant among-center variability unrelated to United Network for Organ Sharing region in the use of older organs in young recipients, ranging from 0% to 25% or greater (overall center median, 9.7%; interquartile range, 5.4-16.5%). There was a significant interaction between donor and recipient age (P < 0.05) such that the impact of older donor age was more pronounced in younger recipients. Transplanting livers from donors aged 40 to 59 years and 60 years or older was associated with worse graft survival in recipients younger than 40 years, but there was no difference based on donor age in recipients 60 years or older. Conclusions. There is a differential impact of using older donors in younger recipients than that in older recipients. Given their longer expected post-LT survival and the ethical imperative to maximize utilization of the scarce resource of transplantable livers, efforts should be made to allocate the highest-quality organs to those most likely to derive lasting benefit

Best Practices in Large Database Clinical Epidemiology Research in Hepatology: Barriers and Opportunities

With advances in computing and information technology, large health care research databases are becoming increasingly accessible to investigators across the world. These rich, population‐level data sources can serve many purposes, such as to generate “real‐world evidence,” to enhance disease phenotyping, or to identify unmet clinical needs, among others. This is of particular relevance to the study of patients with end‐stage liver disease (ESLD), a socioeconomically and clinically heterogeneous population that is frequently under‐represented in clinical trials. This review describes the recommended “best practices” in the execution, reporting, and interpretation of large database clinical epidemiology research in hepatology. The advantages and limitations of selected data sources are reviewed, as well as important concepts on data linkages. The appropriate classification of exposures and outcomes is addressed, and the strategies needed to overcome limitations of the data and minimize bias are explained as they pertain to patients with ESLD and/or liver transplantation (LT) recipients. Lastly, selected statistical concepts are reviewed, from model building to analytic decision making and hypothesis testing. The purpose of this review is to provide the practical insights and knowledge needed to ensure successful and impactful research using large clinical databases in the modern era and advance the study of ESLD and LT

Recipient and Center Factors Associated With Immunosuppression Practice Beyond the First Year After Liver Transplantation and Impact on Outcomes

Background. Immunosuppression is a critical aspect of post-transplant management, yet practices at intermediate and late time points after liver transplantation (LT) are poorly characterized. Methods. A retrospective cohort of 11326 adult first LT alone recipients between 2007 and 2016 was identified by linking United Network for Organ Sharing transplant data to Medicare administrative claims. The immunosuppression regimen was obtained from Medicare billing claims. Factors associated with calcineurin inhibitor (CNI) monotherapy at 1-, 3-, and 5-y post-LT were investigated using mixed-effects logistic regression. Center practice heterogeneity was evaluated. The association of immunosuppression regimen (time-updating) with patient and graft survival was studied. Results. CNI monotherapy was used in 51.9% at 1-y post-LT and 68.6% at 5-y post-LT. Center-specific rates ranged from 20.0%-79.9% to 15.4%-95.2%, respectively. CNI monotherapy at 1- and 3-y post-LT was less likely among Black recipients (P = 0.027 and P = 0.015 versus White, respectively). CNI plus antimetabolite was associated with improved adjusted patient (hazard ratio, 0.59; P < 0.001) and graft (hazard ratio, 0.62; P < 0.001) survival versus CNI monotherapy. The benefit of CNI plus antimetabolite on patient and graft survival increased with older age.Conclusions. In this first longitudinal analysis of LT immunosuppression practices among Medicare beneficiaries, a CNI plus antimetabolite approach led to improved outcomes. Significant center heterogeneity in practice was observed