Measuring and Monitoring Equity in Access to Deceased Donor Lung Transplants among Waitlisted Candidates

Abstract

In 2016, the Organ Procurement and Transplantation Network (OPTN) developed a methodology to measure equity in access to deceased donor kidney transplantation that has since been applied to liver and, most recently, lung. The holistic approach is designed to measure disparities related to geographic, demographic, clinical, and socioeconomic factors while adjusting for factors used to prioritize candidates for allocation, as well as to quantify system-level equity by a single number that can be tracked over time. For OPTN data on active lung candidates we fit 36 separate Poisson rate models over rolling 6-month periods examined quarterly from 1/2010 to 6/2019, adjusting for 15 candidates covariates. Disparity was quantified as the Winsorized standard deviation (SD) of of predicted transplant rates (on log scale) among lung registrations, after "discounting" for desired, policy-induced disparities such as the lung allocation score by holding these factors constant. Risk-adjusted, factor-specific disparities were calculated as the SD of the log(transplant rate), holding all other factors constant. Despite 3 policy modifications over the time period, the overall disparity metric has remained very stable (fig1). Donation service area (DSA) was the factor most independently associated with disparities in access to lung transplant in each period. Other factors that rose to the top, but well below DSA, include gender, ethnicity, diagnosis group, and age. Even after removing DSA as a unit of allocation for lung in 2017, DSA still is the factor contributing the most to inequities. This methodology will be used for monitoring the impact on equity of future policy changes, such as the anticipated transition to "Continuous Distribution" for lungs.