American Journal of Kidney Diseases
Volume 56, Issue 1 , Pages 7-9, July 2010

United Network for Organ Sharing (UNOS) Organ Allocation Policy and Kidney Utilization

  • John D. Scandling, MD

      Affiliations

    • Stanford University, Stanford, California
    • Corresponding Author InformationAddress correspondence to John D. Scandling, MD, Adult Kidney and Pancreas Transplant Program, 750 Welch Rd, Ste 200, Palo Alto, CA 94304
    • ,
  • Douglas J. Norman, MD

      Affiliations

    • Oregon Health & Science University, Portland, Oregon

Article Outline

 

Related Article, p. 95

The United Network for Organ Sharing (UNOS) was incorporated as a nonprofit member organization in 1984, the year the US Congress passed the National Organ Transplant Act. It is a public-private partnership that includes representation of all professionals involved in organ donation and transplants. Since 1986 and its receipt of the first government contract to operate the Organ Procurement and Transplantation Network (OPTN), UNOS has been charged with the development of organ transplant policy, organ matching and placement, and data collection about every transplant occurring in the United States. The primary goals of the OPTN and UNOS are to “increase and ensure the effectiveness, efficiency and equity of organ sharing in the national system of organ allocation” and to “increase the supply of donated organs available for transplantation.”1 Policy development is collaborative and hence frequently results in compromise.

Throughout its history, UNOS has made policy aimed to approximate justice in organ allocation when balancing the often competing goals of equity and utility. This has not been easy. The most recent example in kidney transplantation is the attempt to develop a “kidney allocation score” in response to the 1998 US Health and Human Services Administration Final Rule guidelines calling for measurable data in an allocation system.2, 3, 4, 5, 6, 7, 8 The complexity of the recently proposed system and the factoring of life expectancy in its allocation equation led to its demise, although certain elements likely will carry over into the next iteration.9

Reflecting active compromise between equity and utility, the algorithm by which UNOS allocates deceased donor kidneys has been modified repeatedly over time. The algorithm starts with allocation within ABO blood type groups, with occasional exception. In this issue of the American Journal of Kidney Diseases, Kalyer and Segev10 present an analysis of an exception, the practice of transplants of ABO blood group A deceased donor kidneys into ABO blood group AB recipients. During a recent 10-year period, 1995 through 2004, a total of 1,120 type AB candidates received transplants from type A donors (and 180 received kidneys from type B donors). Although this represented just 110 transplants per year on average, it resulted in a 2-fold greater chance of a type AB candidate receiving a transplant than candidates of other blood types and a 1.5-fold greater chance than a blood group type A candidate. This meant a significantly shorter median waiting time to deceased donor transplant; 18 months for type AB candidates compared with 31-58 months for candidates with other blood types. Type AB candidates were significantly less often recipients of either expanded-criteria donor kidneys or, strikingly, living donor kidneys. The investigators posit that this may have been a consequence of the shorter waiting time for a standard deceased donor transplant. Another surprising finding was a significantly higher discard rate for both standard and expanded criteria deceased donor blood group AB kidneys; 1.7-fold greater than in other blood types in each instance. The investigators again hypothesize that this was a consequence of the shorter waiting time to transplant for AB candidates.

Kayler and Segev10 contend that the practice of type A into type AB deceased donor transplants has advantaged type AB recipients, who are already advantaged in living donor transplants because they are universal recipients. They conclude that ending this practice probably would decrease the waiting time disparity between blood groups A and AB, decrease the discard rate of type AB deceased donor kidneys, and increase the rate of living donor transplant in type AB recipients. They call for a revision of the current UNOS policy (Box 1).11

Box 1. UNOS Policy 3.5.2 ABO Blood Type O Kidneys Into Type O Recipients and Type B Kidneys Into Type B Recipients

“Blood type O kidneys must be transplanted only into blood type O candidates except in the case of zero antigen mismatched candidates (as defined in Policy 3.5.3.1) who have a blood type other than O. Additionally, blood type B kidneys must be transplanted only into blood type B candidates except in the case of zero antigen mismatched candidates (as defined in Policy 3.5.3.1) who have a blood type other than B. Therefore, kidneys from a blood type O donor are to be allocated only to blood type O candidates and kidneys from a blood type B donor are to be allocated only to blood type B candidates, with the exception for zero antigen mismatched candidates noted above. This policy, however, does not nullify the physician's responsibility to use appropriate medical judgment in an extreme circumstance.”

As early as November 4, 1987, UNOS policy required the transplant of ABO blood group O donor kidneys only into type O recipients (D. Heiney, UNOS, personal communication, March 26, 2010). This ended the practice of the use of type O donors as universal kidney donors, which had led to a burgeoning list of “orphan” type O patients awaiting transplant. By 1988, UNOS policy also restricted the transplant of type B donor kidneys into type B recipients only. UNOS policy has never explicitly restricted the transplant of type A kidneys into type A recipients only, allowing for transplant of these organs into type AB recipients. The collective memory of the events that led to an exclusion of requiring transplants of type A into only type A is that there was a surfeit of type A donors and the waiting time for type A patients was substantially shorter than that of type O patients due to the prior practice of the use of type O donors as universal donors. Consequently, the current practice of transplants of type A into type AB has been the result of a passive and not an active policy.

How widespread the practice has been is unclear. In the San Francisco Bay area, type A kidneys have not gone into type AB recipients since the approval of an allocation variance by UNOS in 1994 (the primary feature of the variance is that allocation is based on waiting time alone; S. Van Slyck, California Transplant Donor Network, personal communication, March 8, 2010). Therefore, on the basis of at least this 1 organ procurement organization exception, allocation of type A kidneys into type AB recipients has not been a uniform national practice. However, this practice has continued beyond the period studied (1995-2004). There were 180 transplants of deceased donor type A into type AB in 2008, and 214 in 2009 (M.D. Ellison, UNOS, personal communication, March 26, 2010). These represented 5% of transplants from all type A donors and 36% of transplants into type AB recipients (M.D. Ellison, UNOS, personal communication, March 26, 2010), similar to the figures reported by Kayler and Segev.10

Blood group AB candidates represented only 4% of those awaiting transplant during the 10-year study period. A refinement to UNOS Policy 3.5.2, to add the restriction of transplant of blood type A deceased donor kidneys into only blood type A candidates, would immediately directly affect only this small, but advantaged, percentage of transplant candidates. If this action led to a realization of the predictions of decreased discard of type AB deceased donor kidneys and an increase of living donor transplant in type AB recipients, both type AB and A candidates would benefit due to the increase in their respective donor pools. To continue to approximate justice in organ allocation, revising UNOS Policy 3.5.2 to restrict transplant of type A kidneys into type A candidates only would be the right thing to do.

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Acknowledgements 

Financial Disclosure: The authors declare that they have no relevant financial interests.

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References 

  1. The Organ Procurement and Transplantation Network, United Network for Organ Sharing. Who we are: the OPTN. www.unos.org/whoWeAre/theOPTN.aspAccessed April 13, 2010
  2. Murphy B, Vincenti F, Meier-Kriesche H-U. The AST's perspective on the proposed kidney allocation system. Am J Transplant. 2009;9(7):1500
  3. Freeman RB, Matas AT, Henry M, Segev DL, Kaufman DB, Roberts JP. Moving kidney allocation forward: the ASTS perspective. Am J Transplant. 2009;9(7):1501–1506
  4. Hippen B. The kidney allocation score: methodological problems, moral concerns and unintended consequences. Am J Transplant. 2009;9(7):1507–1512
  5. Segev DL. Evaluating options for utility-based kidney allocation. Am J Transplant. 2009;9(7):1513–1518
  6. Stock PG. Balancing multiple and conflicting allocation goals: a logical path forward. Am J Transplant. 2009;9(7):1519–1522
  7. Wolfe RA, McCullough KP, Leichtman AB. Predictability of survival models for waiting list and transplant patients: calculating LYFT. Am J Transplant. 2009;9(7):1523–1527
  8. Stegall MD. Developing a new kidney allocation policy: the rationale for including life years from transplant. Am J Transplant. 2009;9(7):1528–1532
  9. Bromberg J, Gill J. Heavy LYFTing: KASting pearls before swine. Am J Transplant. 2009;9(7):1489–1490
  10. Kayler LK, Segev DL. The impact of nonidentical ABO deceased donor kidney transplant on kidney utilization. Am J Kidney Dis. 2010;56(1):95–101
  11. United Network for Organ Sharing. What we do: policies. http://www.unos.org/policiesandbylaws/policies.aspAccessed April 13, 2010

PII: S0272-6386(10)00720-1

doi:10.1053/j.ajkd.2010.04.004

Refers to article:

  • The Impact of Nonidentical ABO Deceased Donor Kidney Transplant on Kidney Utilization , 29 March 2010

    Liise K. Kayler, Dorry L. Segev
    American Journal of Kidney Diseases July 2010 (Vol. 56, Issue 1, Pages 95-101)

American Journal of Kidney Diseases
Volume 56, Issue 1 , Pages 7-9, July 2010

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