Correcting the Sex Disparity in MELD-na

Nicholas L. Wood; Douglas VanDerwerken; Dorry L. Segev; Sommer E. Gentry

Disclosures

American Journal of Transplantation. 2021;21(10):3296-3304. 

In This Article

Results

Study Population

Our study population consisted of 73 846 men and 45 478 women. Table 1 shows demographic data comparing the men and women in our cohort. Women had lower serum creatinine and lower MELD-Na at listing, and women were also less likely to be listed with hepatitis C, alcoholic cirrhosis, and alcoholic cirrhosis with hepatitis C, and more likely to be listed with NASH. Table 2 shows the distribution of MELD-Na (or MELD-Na correction) scores in our study population, stratified according to the acuity circles allocation system.

Survival Analysis by MELD-Na and MELD-Na Corrections

MELD-Na. The 90-day without-transplant survival for men is higher than survival for women at most MELD-Na scores between 15 and 35, although the difference is small, at most about 5 percentage points (Figure 1A and 2A).

Figure 1.

Ninety-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 [Color figure can be viewed at wileyonlinelibrary.com]

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

MELD-Na-MDRD. The MELD-Na-MDRD correction increases female MELD-Na from 0 to 3 points depending on her serum creatinine, bilirubin, INR, and serum sodium. Under this correction, survival for women tends to be higher than survival for men at most MELD-Na/MELD-Na-MDRD scores. For most scores between 15 and 35, women had significantly higher 90-day without-transplant survival than men, although again the difference is small (Figure 1B and 2B). This indicates that using the MELD-Na-MDRD correction for women would be an overcorrection.

MELD-GRAIL-Na. Using MELD-GRAIL-Na, men do not consistently have higher 90-day without-transplant survival compared to women, nor vice versa. MELD-GRAIL-Na seems to correct the without-transplant survival differences between men and women seen in MELD-Na (Figure 1C and 2C).

MELD-Na-Shift. To equalize the 90-day without-transplant survival rate based on our 3.2.1 above, women had their MELD-Na score shifted according to Table 3. There are some scores for women under MELD-Na-Shift which cannot be obtained, because after shifting there are no longer any women at that MELD-Na score (e.g., 16). Without-transplant survival and differences for those scores are interpolated from survival of the neighboring scores (e.g., 15 and 17).

With MELD-Na-Shift, men do not consistently have higher 90-day without-transplant survival compared to women, nor vice versa. MELD-Na-Shift seems to correct the without-transplant survival differences between men and women seen in MELD-Na (Figure 1D and 2D).

Simulation Study

To test the impact of the above approaches in the real world, we simulated using each of the three corrections to MELD-Na for allocation in LSAM under the acuity circle allocation system. All proposed corrections would increase the number of transplants and decrease the number of waitlist deaths for women, and consequently would decrease the number of transplants and increase the number of waitlist deaths for men (Table 4).

Transplant rates for men and women using MELD-Na and each MELD-Na correction are recorded in Table 5. Using MELD-Na, women were transplanted at 94.50% of the rate of men (37.27 vs. 35.22 transplants per 100 patient-years, p < 0.0001). Using the corrections, MELD-Na-MDRD resulted in women being transplanted at 108.11% of the rate of men (35.51 vs. 38.35 transplants per 100 patient-years, p = 0.0025), MELD-GRAIL-Na resulted in women being transplanted at 105.25% of the rate of men (35.71 vs. 37.57 transplants per 100 patient-years, p = 0.0079), and MELD-Na-Shift resulted in women being transplanted at 99.44% of the rate of men (36.61 vs. 36.40 transplants per 100 patient-years, p = 0.4044). MELD-Na-MDRD and MELD-GRAIL-Na overcorrected the difference in transplant rates between men and women, whereas MELD-Na-Shift eliminated the difference.

Mortality rates for men and women using MELD-Na and each MELD-Na correction are recorded in Table 6. Using MELD-Na, women died on the waitlist at 101.80% of the rate of men (17.24 vs. 17.55 deaths per 100 patient-years, p = 0.0255). Using the corrections, MELD-Na-MDRD resulted in women dying on the waitlist at 96.90% of the rate of men (17.42 vs. 16.88 deaths per 100 patient-years, p = 0.0006), MELD-GRAIL-Na resulted in women dying on the waitlist at 97.28% of the rate of men (17.31 vs. 16.84 deaths per 100 patient-years, p = 0.0005), and MELD-Na-Shift resulted in women dying on the waitlist at 99.71% of the rate of men (17.32 vs. 17.27 deaths per 100 patient-years, p = 0.7070). MELD-Na-MDRD and MELD-GRAIL-Na overcorrected the difference in mortality rates between men and women, whereas MELD-Na-Shift eliminated the difference.

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