Sex disparity in liver allocation within Eurotransplant

• DOI: 10.1016/j.ajt.2024.06.018
• Publication Date: 2024-07-09T16:06:54Z
• Authors: Hans C. de Ferrante; Marieke De Rosner...; Bart M.L. Smeulders; Serge Vogelaar; Frits C.R. Spieksma
• Keywords: size mismatch; Eurotransplant; allocation; sex disparity; mediation analysis; MELD

In Eurotransplant, relatively more females than males die while waiting for a liver transplantation, and relatively fewer females are transplanted. With adult liver transplantation candidates listed between 2007 and 2019 (n=21,170), we study whether sex disparity is inherent to the Model for End-stage Liver Disease (MELD) scoring system, or the indirect result of a small candidate body size limiting access to transplantation. Cox proportional hazards models are used to quantify the direct effect of sex on waitlist mortality, independent of sex's effect through MELD scores, and the direct effect of sex on the transplantation rate, independent of sex's effect through MELD and candidate body size. Adjusted waitlist mortality hazard ratios for female sex are insignificant (HR: 1.03, 95%-CI: 0.88-1.20). We thus lack evidence that MELD systematically underestimates waitlist mortality rates for females. Transplantation rates are 25% lower for females than males in unadjusted analyses (HR: 0.74, 95%-CI: 0.71-0.77), but hazard ratios become insignificant with adjustment for mediators (HR: 0.98, 95%-CI: 0.93-1.04), most importantly candidate body size. Sex disparity in Eurotransplant thus appears to be largely a consequence of lower transplantation rates for females, which are explained by sex differences in body size.