A Pitfall in the Current Kidney Allocation Process Using Calculated PRA(CPRA) in Patients Undergoing Desensitization

Abstract

To the Editor: The article by Cecka (1) presents a compelling rationale for the superiority of the new Current Kidney Allocation Process Using Calculated PRA (CPRA) compared to the old system in determining which kidney waitlist candidates are eligible for the four additional points awarded to the highly sensitized subset (CPRA ≥ 80%). There is a consensus that CPRA usage allows a more standardized means of allocating deceased donor kidneys. It remains to be seen if this change will result in any additional benefit for the highly sensitized patients with extremely long waiting times. Transplant centers nationally have attempted to help these patients using desensitization modalities like IVIG, Plasmapheresis, Rituximab and combinations thereof. Our center like many others has successfully used desensitization for patients awaiting a deceased donor kidney with at least 5 years of waiting time. Under the new allocation system, patients who undergo desensitization lose their CPRA points as their avoid antigen list is removed from UNet SM and their CPRA decreases, thus facing an interesting paradox. As they widen their access to deceased donor kidneys, their position on the waitlist goes down. Desensitization is time and labor intensive for both the transplant candidates and their respective centers. Any delay after successful desensitization can be deleterious due to antibody rebound. According to Organ Procurement and Transplantation Network (OPTN) data, the median waiting time for highly sensitized kidney candidates listed in 1999‐2000 was over 10 years, more than double the moderately (PRA = 10‐79%) and nonsensitized (PRA <10%) groups (2). This occurred despite an allocation system with sensitization points designed to assist this group in obtaining fair access to transplantation. In addition, desensitization therapies were in use to also assist this group without loss of sensitization points. This suggests that the current system that does not make allowances for those undergoing desensitization may have a weakness that was not present in the previous system. This concern was scrutinized at the HistocompatibilityCommitteemeetinginNovember2009withtwomain suggestions for improvement of CPRA policy. The first is the retention of any predesensitization CPRA points for 1 year after treatment with an IRB-approved desensitization protocol. The second is implementation of a sliding scale for awarding CPRA points including patients with CPRA <80% (3). Scientific Registry of Transplant Recipients has made recommendations to add desensitization status to OPTN data forms to assist with risk adjustment issues relevant to Centers for Medicare & Medicaid Services because of the added investment these patients require and their high potential for adverse outcomes (4). This increased risk is in part due to prolonged waiting times because of the highly sensitized patients’ restricted access to transplantation. Mechanisms to improve this access are required for fairness and may improve outcomes for this group. We wish to bring these issues to the forefront of the transplant community’s consciousness to assist in decision making when a formal proposal by the UNOS Histocompatibilty Committee is circulated for public comment.