*Purpose: When a transplant program removes a candidate from the waitlist, they must either select a pre-defined removal code or type a response into the “Other, specify” option. The “Other, specify” option for entering a waitlist removal justification allows transplant programs to record a broad range of circumstances that contribute to waitlist removal. These circumstances include factors not captured in the pre-defined removal codes including factors related to non-medical reasons for removal and social determinants of health. However, analyzing the “Other, specify” free-text comments are difficult with traditional analytics. We leverage natural language processing and manual review to characterize common themes for waitlist removal based on the free-text justifications.

*Methods: We collected transplant waitlist records from registrations between 2010 and 2019 from the Organ Procurement and Transplantation Network registries. We manually reviewed a small sample of registrations with “Other, specify” as their removal reason in order to identify an initial list of common themes and keywords associated with each theme. We then applied a topic modelling algorithm to the entire set of “Other, specify” removal justifications in order to identify additional themes and keywords. Each “Other, specify” justification was then categorized into themes based on the keywords previously identified. We used chi-square tests to assess associations between removal themes and demographic factors like race/ethnicity.

*Results: Of 579,783 removals in the cohort, 46,360 (8.0%) removals had “Other, specify” reasons for delisting. We established nine themes among these “Other, specify” reasons including multiple themes reflecting social determinants of health such as financial difficulties (7.60% of “Other, specify” removals) or lack of an adequate support system (4.30%). The most common theme was noncompliance with hospital requirements (26.40%) (Figure 1). White transplant candidates were less likely to be removed for financial reasons (6.0% of white candidate removals) than black (7.6%; χ² = 22.6), Hispanic (14.3%; χ² = 332.9), or all other races/ethnicities (12.0%; χ² = 99.3; p < 0.001 in all tests).

*Conclusions: Although transplant candidates are removed from the waitlist due to various factors including social determinants of health, many of these factors are only apparent in the free-text removal justifications. We present a methodology to quantitatively characterize these non-medical factors influencing access to transplant.

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