Correcting the sex disparity in MELD-Na

Abstract

MELD-Na appears to disadvantage women awaiting liver transplant by underestimating their mortality rate. Fixing this problem involves: (1) estimating the magnitude of this disadvantage separately for each MELD-Na, (2) designing a correction for each MELD-Na, and (3) evaluating corrections to MELD-Na using simulated allocation. Using Kaplan-Meier modeling, we calculated 90-day without-transplant survival for men and women, separately at each MELD-Na. For most scores between 15 and 35, without-transplant survival was higher for men by 0-5 percentage points. We tested two proposed corrections to MELD-Na (MELD-Na-MDRD and MELD-GRAIL-Na), and one correction we developed (MELD-Na-Shift) to target the differences we quantified in survival across the MELD-Na spectrum. In terms of without-transplant survival, MELD-Na-MDRD overcorrected sex differences while MELD-GRAIL-Na and MELD-Na-Shift eliminated them. Estimating the impact of implementing these corrections with the liver simulated allocation model, we found that MELD-Na-Shift alone eliminated sex disparity in transplant rates (p = 0.4044) and mortality rates (p = 0.7070); transplant rates and mortality rates were overcorrected by MELD-Na-MDRD (p = 0.0025, p = 0.0006) and MELD-GRAIL-Na (p = 0.0079, p = 0.0005). We designed a corrected MELD-Na that eliminates sex disparities in without-transplant survival, but allocation changes directing smaller livers to shorter candidates may also be needed to equalize women's access to liver transplant.

Keywords: classification systems: Model for Endstage Liver Disease (MELD); disparities; ethics and public policy; gender; liver transplantation/hepatology; mathematical model; organ procurement and allocation; simulation; translational research/science.

Figure 1.

90-day without-transplant survival for men and women: (a) by MELD-Na, (b) by MELD-Na for men and MELD-Na-MDRD for women, (c) MELD-GRAIL-Na, and (d) by MELD-Na for men and MELD-Na-Shift for women. Scores below 15 were omitted because those candidates are rarely transplanted and because survival differences were always negligible.

Figure 2.

Difference in 90-day without transplant survival (men – women) with marginal 95% confidence intervals: (a) by MELD-Na, (b) by MELD-Na for men and MELD-Na-MDRD for women, (c) MELD-GRAIL-Na, and (d) by MELD-Na for men and MELD-Na-Shift for women. Scores below 15 were omitted because those candidates are rarely transplanted and because survival differences were always negligible.