Gender disparity in liver transplant waiting-list mortality: the importance of kidney function

Abstract

Previous studies of men and women on the liver transplantation (LT) waiting list, without taking transplantation rates into account, have suggested a higher risk of mortality for women on the waiting list. The objective of this study was to compare men and women with respect to dying within 3 years of registration on the LT waiting list and to take into account both the immediate mortality risks and the transplantation rates. The analysis was based on Organ Procurement and Transplantation Network data for patients with end-stage liver disease (ESLD) on the waiting list who were registered between February 2002 and August 2009. Competing risk survival analysis was performed to assess the gender disparity in waiting-list mortality; 42,322 patients and 610,762 person-months of waiting-list experience were included in the analysis. The risk of dying within 3 years of listing was 19% and 17% in women and men, respectively (P < 0.0001). Among patients with kidney disease and especially those not on dialysis with an estimated glomerular filtration rate (eGFR) ≥15 and <30 mL/minute/1.73 m(2), women had a substantially higher risk of dying on the waiting list within 3 years of registration versus men (26% versus 20%, P = 0.001). This disparity was related to lower transplantation rates in women (transplantation rate ratio = 0.68, P < 0.0001). Controlling for eGFR and other variables related to mortality risk, we found that the overall female-male disparity disappeared. In conclusion, among patients with ESLD and kidney dysfunction who are not on dialysis, there is a substantial gender disparity in LT waiting-list mortality. Our analysis suggests as an explanation the fact that women have lower transplantation rates than men in this group. The lower transplantation rates can be explained in part by the fact that Model for End-Stage Liver Disease scores tend to be lower for women versus men because they are based on serum creatinine rather than the glomerular filtration rate.

Figure 1

Cumulative incidence of death, LT, and removal from the LT waiting list due to deterioration (A,C,E) in the entire cohort (controlled for age, ethnicity, etiology, region, blood type, diabetes, dialysis, and MELD score) and (B,D,F) in the subgroup of patients not on dialysis with eGFR values ≥15 and <30 mL/minute/1.73 m² (stage 4 kidney disease) (controlled for age, ethnicity, etiology, region, blood type, diabetes, and MELD score). These risk estimates apply specifically to those with mean or mode values of the predictors (ie, age of 54 years, hepatitis C infection, blood type O, white ethnicity, no diabetes, and region 5). The MELD score was set to 20 to obtain moderate estimates of death and transplantation.

Figure 2

Liver transplantation rates (per person-year) in women and men by MELD score.