Women die waiting for livers

A 2020 study found women were 8.6 percent more likely than men to die waiting for a liver transplant and 14.4 percent less likely to receive one.

The MELD system ranks transplant candidates

The Model for End-Stage Liver Disease, used since 2002, ranks candidates on the waiting list based on how likely they are to survive without a transplant in the short term.

Creatinine levels create the bias

MELD uses creatinine, a waste product from muscles, to assess kidney function. Women have lower muscle mass than men, so identical kidney dysfunction produces different creatinine levels.

Lower creatinine makes women seem healthier

The original MELD model did not account for sex differences in muscle mass. Lower creatinine in women's blood made them appear healthier than they were, pushing them down the waiting list.

MELD 3.0 adds points for women

In 2023, Dr. Ray Kim, who developed the original system, debuted MELD 3.0. It adds 1.33 points to women's scores to correct for creatinine differences and improve accuracy for all patients.

Early gains were temporary

An analysis of nearly 10 million daily records from over 60,000 candidates found that liver transplant rates for women increased after MELD 3.0 was implemented but the increase was temporary.

Women's gains faded within 15 months

Women's estimated odds of receiving a transplant drifted back to pre-MELD 3.0 levels by the end of the study period, 15 months after the new model was implemented.

The catchup effect explained the surge

The authors believe the early surge was a onetime catchup. MELD 3.0 pushed a group of women stuck on the list over the priority threshold all at once, leading them to receive transplants.

Women got more offers but not livers

Under MELD 3.0, women received more organ offers than before, probably because their more accurate scores better reflected how sick they were. But they are not necessarily receiving those livers.

Body size is the second problem

A transplanted liver must physically fit inside the recipient's body. Women are typically smaller than men, so a very large liver cannot be offered to a small woman.

Smaller patients wait longer

Sommer Gentry, a professor at NYU Grossman School of Medicine, said the smaller you are, the less likely you are to be offered something that will work for you. Women end up waiting longer.

“The smaller you are, the less likely you are to be offered something that's actually going to work for you.”

MELD 3.0 did not address body size

Gentry said that creatinine and body size are the two main problems creating disparity in liver access for women. MELD 3.0 was an attempt to remove the former barrier only.

Revising MELD alone may not be enough

These findings suggest that revising the MELD criteria alone may not be enough to eliminate the sex disparity, especially if the body-size disadvantage is part of the problem.

Sex is a proxy for the real issue

The authors say that a patient's sex is merely a poor proxy for the real issue.

Size matters across organ types

Body-size disparity affects the organ allocation system in general. Similar issues arise with heart and lung transplants too, where the size of the organ relative to body size must be considered.

A size-aware system could help everyone

Gentry said a size-aware organ allocation system would benefit patients on the waiting list across the board. Smaller livers could be offered first to the smallest candidates who are also sickest.

Regulatory approval and research needed

For such a policy to be instituted, the Organ Procurement and Transplantation Network would have to approve it. Before such a system could be presented to the regulatory organization, more research is required.

Medical standards often favour men

It is often the case in medicine that our definition of what counts as a healthy body is measured against the average white male.

Body size is the real bottleneck

While fixing the model to rank women more accurately on the liver waiting list is a start, including body-size considerations in the organ allocation system might be the real bottleneck to address.

“There's no mechanism right now, if a small liver is available, for offering it preferentially to the small women who might not be able to accept lots of other organs that are becoming available.”