A Conceptual Model for Sources of Selection Bias in Lung Transplant Allocation

Abstract

<h3>Purpose</h3> In the U.S., donor lungs are allocated to transplant candidates based on the lung allocation score (LAS). However, additional factors beyond the LAS can impact who is transplanted, including referral, listing, and donor organ acceptance practices. These factors can undermine the fairness of lung allocation, but they have not been systematically studied using formal qualitative methods. <h3>Methods</h3> We conducted a semi-structured qualitative interview study of lung transplant surgeons and pulmonologists in the U.S. between June 2019 and June 2020 to understand the role that the LAS plays in clinical decision making, how transplant clinicians think about selection and survivor bias in lung allocation, and whether they feel the LAS should be modified to account for such biases. <h3>Results</h3> Our 51 respondents (30 transplant surgeons and 21 pulmonologists) identified many sources of selection/survivor bias arising at several points along the pathway from referral to transplantation. We developed a conceptual model synthesizing these sources of selection/survivor bias into five factors: 1) transplant center's level of risk tolerance and accountability, 2) successfulness and fairness of the LAS in mitigating selection bias, 3) donor organ availability and regional competition, 4) patient health versus program health, and 5) access to care versus responsible stewardship of organs. <h3>Conclusion</h3> Our proposed conceptual model demonstrates how selection bias can arise throughout lung transplantation and can facilitate further study of such bias. As the transplant community continues to develop and implement new allocation models for lung and other organs, the sources of selection bias described here should be considered carefully to ensure that the resulting allocation scheme is truly more equitable.