MELD Eliminated Racial Disparities in Liver Transplantation, but Women Are Still at a Disadvantage

By Liz Highleyman

Over years or decades, people with chronic liver disease -- including hepatitis B or C -- may develop advanced liver damage including cirrhosis or hepatocellular carcinoma. Liver transplantation is the only treatment for end-stage liver disease, but there is a severe shortage of suitable donor organs.

In February 2002, the United Network for Organ Sharing (UNOS) adopted a new allocation scheme for liver transplants. The MELD (Model for End-Stage Liver Disease) system estimates the risk of death within 3 months based on measurement of bilirubin, creatinine, and prothrombin time (a measure of blood clotting). The goal is to prioritize patients who have the greatest need for a new liver, but not those who are too sick to undergo the procedure.

According to a report in the November 26, 2008 Journal of the American Medical Association, the MELD scheme reduced previous racial disparities among transplant recipients, but women are still less likely than men to get new livers.

Cynthia Moylan from Duke University Medical Center and colleagues assessed the association between race, sex, and outcomes of deceased donor liver transplantation outcomes following adoption of MELD system in a retrospective cohort of 21,895 adult patients on the UNOS liver transplant waiting list between January 1996 and December 2000 (pre-MELD) and 23,793 patients added between February 2002 and March 2006 (post-MELD).

Separate multivariate analyses were performed for each period to identify predictors of time to death and the odds of dying or receiving a liver transplant within 3 years of listing. Patients with hepatocellular carcinoma were analyzed separately.

Results

Overall, black patients were significantly younger and sicker than white patients on the waiting list during both periods:

mean age 49.2 vs 52.4 years, respectively;

median MELD score at the time of listing 16 vs 14, respectively.

In the pre-MELD cohort, black patients were more likely than whites to die or become too sick for liver transplantation within 3 years of joining the waiting list (27.0% vs 21.7%; odds ratio [OR] 1.51; P = 0.003).

In the post-MELD cohort, black race was no longer associated with increased likelihood of death or becoming too sick for transplantation (26.5% vs 22.0%; OR, 0.96; P = 0.76, non-significant).

During the pre-MELD period, black patients were also significantly less likely than whites to receive a liver transplant within 3 years of joining the waiting list (61.6% vs 66.9%; OR 0.75; P = 0.03).

During the post-MELD period -- though the likelihood decreased overall -- blacks were no longer significantly less likely than whites to receive a transplant (47.5% vs 45.5%; OR 1.04; P = 0.75).

Women were more likely than men to die or become too sick for liver transplantation both pre-MELD (22.4% vs 21.9%; OR 1.08; P = 0.37) and post-MELD (23.7% vs 21.4%; OR 1.30; P = 0.003).

Similarly, women were less likely than men to receive a transplant within 3 years of listing both pre-MELD (64.8% vs 67.6%; OR 0.80; P = 0.002) and post-MELD (39.9% vs 48.7%; OR 0.70; P < 0.001).

Based on these findings, the study authors concluded, "Following introduction of the MELD score to the liver transplantation allocation system, race was no longer associated with receipt of a liver transplant or death on the waiting list, but disparities based on sex remain."

To explain these results, they noted that the MELD score accounts for the severity of disease when a patient is put on the waiting list, and since blacks are sicker on average, they are more likely to receive a donor liver under the new system.

Women may be less likely to receive a transplant due to their smaller average body size, since small donor livers may be given to children and large patients, but small patients may not be able to receive large livers.

In an accompanying editorial, David Axelrod of Dartmouth-Hitchcock Medical Center and Elizabeth Pomfret of the Lahey Clinic Medical Center wrote, "When compared with the system before 2002, the current MELD system is clearly a step toward achieving the goal of an equitable, efficient, and transparent organ allocation system."

"The MELD system appears to have reduced, but likely not eliminated, differential access based on race and ethnicity," they continued. "However, modest differences based on sex persist, but could be addressed by revisions in the organ allocation policy to ensure that MELD scores are comparable across sexes."

Division of Gastroenterology, Duke University Medical Center, Durham, NC.

1/16/09

References
CA Moylan, CW Brady, JL Johnson, and others. Disparities in liver transplantation before and after introduction of the MELD score. Journal of the American Medical Association 300(20): 2371-2318. November 26, 2008. (Abstract and full text).

DA Axelrod and EA Pomfret. Race and Sex Disparities in Liver Transplantation: Progress Toward Achieving Equal Access? Journal of the American Medical Association 300(20): 2425-2426. November 26, 2008.

Other source
JAMA. Under New Liver Transplantation Allocation System, Improvement Seen Regarding Disparities For Black Patients, But Not for Women. Media Advisory. November 25, 2008.