Liver transplant outcomes have continuously improved over the last several decades: 1-year patient survival rates greater than 80% have been achieved, and liver transplantation remains the most efficacious treatment for patients with end-stage liver disease.1, 2 Unfortunately, because of the severe organ shortage in the United States, more than 16,000 patients are currently awaiting liver transplantation.2 Consequently, depending on the donation service area, approximately 10% to 30% of liver transplant candidates are removed from the wait-list before transplantation because of either death or a deteriorating medical condition.3 Improving the supply of organs, which could be accomplished by increasing the donation rate (eg, presumed consent), augmenting the organ yield per donor, lowering the organ quality threshold, or using alternate sources (eg, living donors and donors after cardiac death), would also reduce demand and lead to shorter wait times and lower disease acuity at the time of transplantation, and all of this could improve patient outcomes and reduce dropout.
In 2003, the US Health Resources and Services Administration, the Centers for Medicare and Medicaid Services, and several organ procurement organizations formed a collaborative to formulate strategies for addressing wait-list mortality and expanding the number of organs available for liver transplantation. One strategy offered by the group was to increase the utilization of donation after cardiac death (DCD) organs, and this consequently led to an expansion in the number of DCD liver transplants performed in the United States.4 However, the increased utilization of DCD grafts has well-documented negative medical sequelae, including an increased risk of biliary complications,5-8 greater costs,9 and higher rates of graft failure,10 which have resulted in a flattening of the growth of DCD liver transplantation in the United States since 2006.11 The impact of the integration of the DCD donor pool, however, may have more far-reaching implications.
In this issue of Liver Transplantation, Orman et al.12 detail the trends in liver transplantation since 1988 through an examination of the Organ Procurement and Transplantation Network (OPTN) database. The authors explored the utilization of liver grafts from deceased donors who had at least 1 organ used for transplantation and the factors that led to the discarding of liver grafts. The authors found that the rate of liver discard decreased steadily from 1988 to 2004 and then subsequently increased to 21% of donors in 2010. Using multivariate regression analysis and population attributable risks, the authors then examined the OPTN database from 2004 to 2010 to determine the factors that led to discard. The authors found that several factors contributed to discard, including donor age, body mass index, diabetes, and, most strikingly, DCD. The DCD population attributable risk proportion for nonuse increased dramatically from 8.7% in 2004 to 28.4% in 2010, and this coincided with the change in federal policy encouraging DCD liver transplantation.12 Notably, the overall impact of DCD was small because of the low rates of DCD organ transplantation. However, donor age had a greater impact, presumably because of the broader relevance of this covariate in addition to its strong influence on clinical decision making. The factors found to contribute to discard may partially account for the flattening of the overall liver availability and transplantation rates from 2004 to 2010.
The authors should be commended for thoroughly exploring the trends in liver utilization and factors associated with discard. These findings have significant implications because the US population is aging, becoming more obese, and developing diabetes at an increasing rate.13 If these trends continue, we can expect persistently lower rates of donation in the coming years unless either a lower threshold of organ quality is broadly implemented or other avenues of donor pool expansion are developed. However, the extension of the criteria for suitable organs has had untoward effects, as shown by Orman et al.12 The discarding of livers from DCD donors may reflect poor organ quality and/or the application of more stringent donor selection criteria by transplant centers because of the greater hazard of poor outcomes and a fear of the consequences of regulatory oversight. To preserve DCD liver utilization, the Centers for Medicare and Medicaid Services could consider modifying risk adjustments to exclude DCD liver transplants from punitive action. Moreover, liver allocation policy reforms are necessary to rescue recipients of failing DCD grafts. The other worrisome trend encountered in this study is a decline in donation after brain death liver transplantation. The authors reiterate the concern that a conversion of donation after brain death donors into DCD donors due to provider/family preferences may be partly responsible for this decline; however, this has yet to be substantiated by the available data.
There are several weaknesses of this study that should be noted. The reasons for donor discard are not well captured in the registry; therefore, any associations with nonuse are not causative. The OPTN database includes discarded livers from donors from whom at least 1 organ has been used for transplantation, so DCD donors who either have failed to progress to circulatory death or have not yielded a single organ for transplantation are not available for analysis. Therefore, this study underestimates the magnitude of the negative implications of DCD liver utilization. To capture the full scope of liver discard, data collected by each of the 58 organ procurement organizations should be merged for analysis.
The issues surrounding organ discard in liver transplantation have not been extensively explored in the literature, and this analysis should serve to initiate further inquiry and policy discussion. For example, the implications of reduced liver utilization (despite federal mandates to augment DCD) for overall organ acquisition costs for transplantation should be explored on a national level. In addition, existing protocols that have been shown to maximize donor yields should be studied in a liver transplant setting and implemented if they are effective.14 Finally, the regulatory oversight of DCD liver transplantation should be modified to encourage the utilization of higher risk DCD grafts in recipients for whom these risks are tempered against poor wait-list outcomes.