A Social Determinants of Health Index for Transplant Access

Summary: Social determinants of health (SDOH) are now widely recognized to play a role in many chronic
health conditions. With this recognition, there is a growing body of literature suggesting an important role of
SDOH in access to transplantation services for end stage liver and kidney disease as well. In our own work, we
have demonstrated the presence of unique geographic regions which rank lowest nationally in the rate of
kidney transplantation despite having the highest incident end stage kidney disease rates in the country. These
severely underserved areas were also found to have significantly less favorable social determinants of health
as measured by the Centers for Disease Control (CDC) Social Vulnerability Index (SVI) when compared to
areas with better access to kidney transplantation. We have also demonstrated that regions in which patients
listed for liver transplant with model for end stage liver disease (MELD) exception points have a significant
advantage over patients without exception points are significantly less socially vulnerable as measured by the
SVI compared to regions where MELD exceptions appropriately stratify risk. Others have demonstrated an
association between various other measures and access to transplant such as urbanization, poverty, and
affordable housing. Despite this increasing recognition of the importance of SDOH in transplantation, we still
do not have a robust and widely accepted measure of SDOH relevant for transplant. Instead, we have a body
of literature which has examined individual factors or adapted composite measures such as the SVI which
were designed to capture outcomes other than transplantation. This lack of appropriate measures of SDOH
relevant to transplant has been cited by the Organ Procurement and Transplantation Network (OPTN) liver and
intestine committee as a reason why SDOH will not be incorporated in the next iteration of liver allocation
policy, while at the same time the committee called for development of such measures to allow for data
collection to inform later policies. I propose to fill this knowledge gap through the creation of a robust index of
social determinants of health specifically designed to correlation with access to liver and kidney transplant
services. I will examine a wide variety of measures of SDOH drawn from sources such as the American
Communities Survey and existing indices such as the SVI to determine which specific factors are significantly
associated with access to the kidney and liver transplant waitlists, respectively on a county level, and then
incorporate these factors into indices using multivariable spatial Poisson regression. These measures will in
turn form the basis for futures studies into how SDOH can best be incorporated into more equitable transplant
policies. More specifically, the results of the research proposed in this R03 will provide important preliminary
data on which to base a planned R01 submission aimed at creation of an equitable liver allocation policy which
incorporates SDOH as I transition to an independent research career.

Grant Number: 1R03DK139236-01A1
NIH Institute/Center: NIH
Principal Investigator: Robert Cannon