The Organ Procurement and Transplantation Network implemented Share 35 on June 18, 2013, to broaden deceased donor liver sharing within regional boundaries. We investigated whether increased sharing under Share 35 impacted geographic disparity in deceased donor liver transplantation (DDLT) across donation service areas (DSAs).
Using Scientific Registry of Transplant Recipients June 2009 to June 2017, we identified 86 083 adult liver transplant candidates and retrospectively estimated Model for End-Stage Liver Disease (MELD)-adjusted DDLT rates using nested multilevel Poisson regression with random intercepts for DSA and transplant program. From the variance in DDLT rates across 49 DSAs and 102 programs, we derived the DSA-level median incidence rate ratio (MIRR) of DDLT rates. MIRR is a robust metric of heterogeneity across each hierarchical level; larger MIRR indicates greater disparity.
MIRR was 2.18 pre-Share 35 and 2.16 post-Share 35. Thus, 2 candidates with the same MELD in 2 different DSAs were expected to have a 2.2-fold difference in DDLT rate driven by geography alone. After accounting for program-level heterogeneity, MIRR was attenuated to 2.10 pre-Share 35 and 1.96 post-Share 35. For candidates with MELD 15–34, MIRR decreased from 2.51 pre- to 2.27 post-Share 35, and for candidates with MELD 35–40, MIRR increased from 1.46 pre- to 1.51 post-Share 35, independent of program-level heterogeneity in DDLT. DSA-level heterogeneity in DDLT rates was greater than program-level heterogeneity pre- and post-Share 35.
Geographic disparity substantially impacted DDLT rates before and after Share 35, independent of program-level heterogeneity and particularly for candidates with MELD 35–40. Despite broader sharing, geography remains a major determinant of access to DDLT.
1 Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD.
2 Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, MD.
3 Scientific Registry of Transplant Recipients, Minneapolis, MN.
4 Department of Mathematics, United States Naval Academy, Baltimore, MD.
Received 25 June 2018. Revision received 16 November 2018.
Accepted 16 December 2018.
M.G.B. participated in research design, data analysis, and writing of the paper. S.Z. and E.C. provided analytical support and participated in data analysis. A.B.M. participated in research design and provided analytical support. D.L.S. and S.E.G. participated in research design, writing of the paper, and contributing new analytical tools.
The authors declare no conflicts of interest. The data reported here have been supplied by the Hennepin Healthcare Research Institute as the contractor for the Scientific Registry of Transplant Recipients (SRTR). The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy of or interpretation by the SRTR, UNOS/OPTN, or the US Government.
This work was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases, R01DK111233 on reducing geographic disparities in kidney and liver allocation. D.L.S. and A.B.M. are supported by grant numbers K24DK101828 and K01DK101677 from the National Institute of Diabetes and Digestive and Kidney Diseases, respectively.
Correspondence: Sommer E. Gentry, PhD, Department of Mathematics, 572-C Holloway Rd, United States Naval Academy, Mailstop 9E, Annapolis, MD 21402. (email@example.com).