Impact of estimated liver volume and liver weight on gender disparity in liver transplantation.

Although lower Model for End-Stage Liver Disease (MELD) scores due to lower levels of serum creatinine in women might account for some of the gender disparity in liver transplantation (LT) rates, even within MELD scores, women undergo transplantation at lower rates than men. It is unclear what causes this disparity, but transplant candidate/donor liver size mismatch may be a factor. We analyzed Organ Procurement and Transplantation Network data for patients with end-stage liver disease on the waiting list. A pooled conditional logistic regression analysis was used to assess the association between gender and LT and to determine the degree to which this association was explained by lower MELD scores or liver size. In all, 28,866 patients and 424,001 person-months were included in the analysis. The median estimated liver volume (eLV) and the median estimated liver weight (eLW) were significantly lower for women versus men on the LT waiting list (P < 0.001). When we controlled for the region and the blood type, women were 25% less likely to undergo LT in a given month in comparison with men (P < 0.001). When the MELD score was included in the model, the odds ratio (OR) for gender increased to 0.84, and this suggested that 9 percentage points of the 25% gender disparity were due to the MELD score. When eLV was added to the model, there was an additional 3% increase in the OR for gender, and this suggested that transplant candidate/donor liver size mismatch was an underlying factor for the lower LT rates in women versus men (OR = 0.87, P < 0.001). In conclusion, lower LT rates among women on the waiting list can be explained in part by lower MELD scores, eLVs, and eLWs in comparison with men. However, at least half of the gender disparity still remains unexplained.