Quantifying Sex-Based Disparities in Liver Allocation

Importance: Differences in local organ supply and demand have introduced geographic inequities in the Model for End-stage Liver Disease (MELD) score-based liver allocation system, prompting national debate and patient-initiated lawsuits. No study to our knowledge has quantified the sex disparities in allocation associated with clinical vs geographic characteristics. Objective: To estimate the proportion of sex disparity in wait list mortality and deceased donor liver transplant (DDLT) associated with clinical and geographic characteristics. Design, Setting, and Participants: This retrospective cohort study used adult (age ≥18 years) liver-only transplant listings reported to the Organ Procurement and Transplantation Network from June 18, 2013, through March 1, 2018. Exposure: Liver transplant waiting list. Main Outcomes and Measures: Primary outcomes included wait list mortality and DDLT. Multivariate Cox proportional hazards regression models were constructed, and inverse odds ratio weighting was used to estimate the proportion of disparity across geographic location, MELD score, and candidate anthropometric and liver measurements. Results: Among 81 357 adults wait-listed for liver transplant only, 36.1% were women (mean SD age, 54.7 11.3 years; interquartile range, 49.0-63.0 years) and 63.9% were men (mean SD age, 55.7 10.1 years; interquartile range, 51.0-63.0 years). Compared with men, women were 8.6% more likely to die while on the waiting list (adjusted hazard ratio aHR, 1.11; 95% CI, 1.04-1.18) and were 14.4% less likely to receive a DDLT (aHR, 0.86; 95% CI, 0.84-0.88). In the geographic domain, organ procurement organization was the only variable that was significantly associated with increased disparity between female sex and wait list mortality (22.1% increase; aHR, 1.22; 95% CI, 1.09-1.30); no measure of the geographic domain was associated with DDLT. Laboratory and allocation MELD scores were associated with increases in disparities in wait list mortality: 1.14 (95% CI, 1.09-1.19; 50.1% increase among women) and DDLT: 0.87 (95% CI, 0.86-0.88; 10.3% increase among women). Candidate anthropometric and liver measurements had the strongest association with disparities between men and women in wait list mortality (125.8% increase among women) and DDLT (49.0% increase among women). Conclusions and Relevance: Our findings suggest that addressing geographic disparities alone may not mitigate sex-based disparities, which were associated with the inability of the MELD score to accurately estimate disease severity in women and to account for candidate anthropometric and liver measurements in this study.