An Alternative Kidney Allocation Algorithm: Is It Better, and by What Yardstick?
Version of Record online: 27 JUL 2012
© Copyright 2012 The American Society of Transplantation and the American Society of Transplant Surgeons
American Journal of Transplantation
Volume 12, Issue 8, pages 1973–1974, August 2012
How to Cite
Gill, J. S. (2012), An Alternative Kidney Allocation Algorithm: Is It Better, and by What Yardstick?. American Journal of Transplantation, 12: 1973–1974. doi: 10.1111/j.1600-6143.2012.04137.x
- Issue online: 27 JUL 2012
- Version of Record online: 27 JUL 2012
- Received 02 April 2012, revised 23 April 2012 and accepted for publication 25 April 2012
In this issue of the American Journal of Transplantation, Ross and colleagues reinvigorate the debate regarding changes to kidney allocation in the United States by proposing an alternative to the “80/20” algorithm currently under UNOS review (1).
The proposed “80/20” algorithm, would use a new continuous scale to rank the quality of deceased donor kidneys (The Kidney Donor Profile Index), and allocate the top 20% of all deceased donor kidneys to candidates with the best estimated posttransplant survival (2). The remaining 80% of kidneys would be allocated to candidates who are within 15 years of the donor's age. Criticisms of the 80/20 algorithm include ageism, a possible decrease in living donation among younger patients who will be prioritized to receive the best deceased donor kidneys, and concerns regarding the ability to identify the top 20% of kidneys and patients using models derived from registry data, which were never designed to inform decision making for individual patients and therefore inherently prone to error leading to inequitable allocation (3).
Ross and colleagues argue that their alternative algorithm, Equal Opportunity Supplemented by Fair Innings (EOFI) better achieves NOTAs criteria of balancing efficiency and equity than either the current system or algorithms based on age matching, including the “80/20” algorithm. EOFI is described as a two-step process: The first step (Equal Opportunity) maintains that wait-listed candidates of all ages have an equal chance of transplantation in a given year. This is achieved by ensuring an equal proportion of wait-listed patients are transplanted within predefined age groups. The second step (Fair Innings) maintains that those developing ESRD at a younger age are worse off than those developing ESRD at an older age because they have had fewer healthy life years, and would direct the better quality deceased donor kidneys (measured by donor age) to younger wait-list candidates regardless of comorbidities.
The authors present convincing arguments that the EOFI algorithm is more equitable than either the current system or algorithms based on age matching. However, acceptance of these arguments relies on how fairness is defined. Under the proposed EOFI algorithm, older transplant candidates will wait the same amount of time as younger candidates, making it more equitable than the proposed “80/20” algorithm. However, despite waiting just as long as younger candidates, older candidates would receive inferior quality kidneys. Arguably, it is unfair for older candidates, who have an increased risk of death on the waiting list and a shorter life expectancy, to wait as long as younger candidates. By not providing a mechanism for more rapid transplantation of older patients or others who tolerate dialysis poorly, EOFI probably will not decrease deaths on the waiting list. Similarly, it is not clear why age was chosen as the primary determinant of equity when other objective factors such as race or place of residence might be proposed as equally important factors contributing to disparities in organ allocation.
Ross and colleagues rely on the familiar fair innings argument to justify the allocation of poorer quality kidneys to older candidates. This argument maintains that for healthcare resources to be distributed fairly, every person should receive sufficient healthcare to provide them with the opportunity to live in good health for a normal span of years. There are a number of criticisms of the fair innings argument including the fact that it only considers duration and not quality of life. Similarly, the use of lifespan as the only expression of what is fair in the context of organ allocation is open to criticism. For example, it might be considered unfair that a young nonadherent candidate for repeat transplantation is allocated a better quality kidney than an older first transplant candidate. Finally, fair innings implies that patients will achieve a normal lifespan if they receive the needed treatment (i.e. a transplant). End-stage renal disease (ESRD) patients infrequently achieve a normal lifespan even if successfully transplanted, and the likelihood of reaching a normal lifespan is lower for younger ESRD patients. Because in ESRD the disconnect between chronological age and physiological age is often greatest among younger patients, the use of the fair innings argument to justify the use of age as a basis for healthcare resource allocation may be particularly problematic.
Although EOFI is a preliminary proposal, there are a number of inequities with the current system that are not well addressed by EOFI including race, and geography-related disparities in access to transplantation. Furthermore, some inequities may be exaggerated by EOFI. For example, because EOFI would transplant a similar proportion of wait-listed candidates in different age groups every year, existing age-related inequities in access to the waiting list would be magnified. Increased resources might be required to minimize inequities in access to the waiting list, and wait-list management costs would likely increase if there was an influx of older patients onto the wait list. The potential impact of EOFI on deceased organ donation and utilization is also not directly considered by the authors. Increased utilization of expanded criteria donor is among the most feasible strategies to increase the number of deceased donor kidneys available for transplantation. Under EOFI, transplantation of a fixed proportion of wait-list candidates in each age group could inadvertently limit use of kidneys from older donors, especially if proportional increases in the number of young deceased donor kidneys cannot be attained.
The above considerations are not intended to be critical of Ross and colleagues but rather to highlight the importance of clearly defining the objectives of a new kidney allocation algorithm, so that various alternatives can be reasonably compared. The concepts of efficiency and equity are nebulous constructs that require consensus definitions in the context of organ allocation before development of successful strategies to balance them can be devised. Most of the criticisms of the proposed changes to the existing organ allocation algorithm have understandably focused on the subjective interpretation of equity. However, there has been relatively limited discussion on a comprehensive assessment of the impact on efficiency, including potential impact on living donation, preemptive transplantation, nonprocurement of organs and organ discard, medical management of wait-listed patients and referral patterns for transplantation. Given that the effort to revise kidney allocation in the United States is now into its 7th year, finding the necessary energy, commitment and resources to improve the current system must be acknowledged as a significant threat to the process. The EOFI proposal may or may not be part of the solution, but by presenting a new perspective and drawing comparisons with other strategies under consideration, the authors have made a strong case to continue the kidney allocation debate. Given the number of stakeholders and the shortage of transplantable kidneys, any alternative to the current system will be subject to criticism. It may be impossible to simultaneously maximize utility and equity. Clarity on definitions and what tradeoffs are acceptable is a prerequisite to evaluating the “80/20” proposal and alternatives such as EOFI.
The author of this manuscript has no conflicts of interest to disclose as described by the American Journal of Transplantation.
- 2(OPTN). UNfOSUOPaTN. Concepts for Kidney Allocation.2011 Available at: http://optn.transplant.hrsa.gov/SharedContent-Documents/KidneyConceptDocument.PDF. Accessed March 27, 2012.