Geography remains primary influence in kidney donor allocation post KAS
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Despite recent changes in the national organ allocation system aimed at getting donor kidneys to individuals who would have the best long-term benefit, geography – where a potential recipient lives – still has a major influence in how organs are distributed, according to a new study.
“The Kidney Allocation System fundamentally altered kidney allocation, causing a substantial increase in regional and national sharing that we hypothesized might impact geographic disparities,” Sheng Zhou, MD, and colleagues from Johns Hopkins School of Medicine and School of Health wrote in an article published in the American Journal of Transplantation.
The researchers looked at the deceased donor kidney transplant (DDKT) rate under the Kidney Allocation System (KAS) from June 2015 to December 2016, and compared that with a pre-KAS period (June 2013-December 2014) using records for over 120,000 adult and pediatric patients in the Scientific Registry of Transplant Recipients (SRTR). They developed a measurement tool called the median incidence rate ratio (MIRR) to determine the influence of a potential kidney recipient’s donor service area (DSA) on receiving a donated kidney.
“In other words, if we consider two random candidates with similar allocation points from two different DSAs and compare the candidate in the DSA with greater access to transplantation to the candidate in the DSA with less access, we get an incidence rate ratio (IRR) for the DDKT rates for this pair of DSAs,” the investigators wrote. “We then calculated the IRRs of all DSA pairs, comparing the higher DDKT rate to the lower DDKT rate. MIRR is the median ratio of DDKT rates over all pairs of DSAs.”
Zhou and colleagues found that the geographic disparities – as measured by the MIRR – “remains severe overall” under the KAS. “Geographic location has a larger impact on DDKT rate than (estimated post-transplant survey scores) at or below the 20th percentile, or 3-year waiting time. This seems to contradict ‘the Final Rule,’ which states that neither place of residence nor place of listing should be a major determinant of access to a transplant,” they wrote.
The KAS uses a scoring system that considers improved longevity of the recipient post-transplant to distribute decreased donor kidneys and was developed in part to provide greater access to candidates with B type blood, the investigators noted. Under KAS, the points a recipient receives while waitlisted are influenced by the Estimated Post Transplant Survival score, waiting time, candidate age, calculated panel reactive antibody score, blood type, and whether the candidate is a prior living donor. “These changes have been accompanied by broader sharing for sensitized candidates, broader sharing for (Kidney Donor Profile Index) over 85, and elimination of local policy variances,” and it has helped to reduce geographic influence, the investigators acknowledged, even though KAS was not designed for that purpose.
Despite that improvement, the researchers say geographic influence is still a major determinant in where and how kidney organs are distributed. “The impact of geography was greater than the impact of factors emphasized by KAS” in the study, they noted. “Despite extensive changes to kidney allocation under KAS, geography remains a primary determinant of access to DDKT.” – by Mark E. Neumann
Disclosure: The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases, Grant/Award Number 1R01DK111233-01. The authors list no relevant financial disclosures.