Liver Transplantation: MELD Makes a Difference
A new system that prioritizes liver transplant patients based on need instead of time on the waiting list has eliminated racial disparities among candidates waiting for new organs, although inequities associated with gender persist, say researchers at Duke University Medical Center.
Why was this study conducted?
The study is the first comprehensive review of organ allocation following adoption of the MELD (Model for End-Stage Liver Disease) score six years ago. Before MELD, patients on the waiting list who were very sick could be passed over for someone who was not as ill but who had been waiting longer. Historically, blacks have come onto transplant waiting lists sicker, with later stage disease, but were often passed over in favor of white patients, who had gotten on the list earlier and healthier. In 2002, the new MELD system went into effect, and now is used throughout the U.S.
Cynthia Moylan, MD, a fellow in the division of gastroenterology at Duke, led a team of researchers that compared variables among patients registered on the United Network for Organ Sharing liver transplantation lists during two periods, from January 1996 and December 2000 (before MELD) and between February 2002 and March 2006, after MELD was introduced. Investigators studied factors related to death, waiting time and receiving a liver within three years of being listed.
What did the research show?
Blacks represented about 10 percent of the liver transplant population during the study period. Overall, black patients tended to be younger, female and less educated than whites. In the post-MELD years, blacks were also significantly more likely to have additional health problems, like diabetes, high blood pressure and kidney failure.
Adjusting for all factors that could affect outcomes, investigators found that black patients were significantly less likely than whites to receive a new liver within three years of being listed during the pre-MELD years (61.66 percent vs. 66.9 percent, respectively (p =.03), but not after MELD went into effect (47.5 percent vs. 45.4 percent, ( p =.75)
Blacks, compared to whites, also faced significantly greater risk of dying or becoming too sick for a transplant during the pre-MELD era (26.98 percent vs. 21.7 percent, respectively (p = .003), but not after MELD was introduced, 26.5 percent vs. 22 percent (p =.76).
While appearing to resolve racial disparities in liver transplant, the MELD system has been less successful in reducing disparities associated with gender. In a secondary analysis, investigators found that gender was significantly associated with death and liver transplantation after taking into account race, despite the use of the MELD score.
Why are these findings important?
- Before MELD, there was clearly a significant racial disparity in liver transplantation that led to a greater risk of death or ability to undergo transplant among blacks.
- The change in policy with implementation of MELD has quickly helped restore racial parity between blacks and whites in liver transplantation.
- For unknown reasons, MELD is not leveling the playing field in liver transplantation between men and women. A clear bias in favor of men exists in the post-MELD era.
What are the implications of this study?
The most important implication is that policy changes that align organ allocation with objective, laboratory-based variables can, indeed, mediate racial imbalance in liver transplantation.
What do the authors have to say about this study?
"This is the first study to assess how MELD has affected racial and gender disparity in liver transplantation," says Moylan. "It revealed that MELD has done a good job in eliminating some of the bias in liver transplantation, but also points out that there is still work that needs to be done to answer two important questions: First, why do women appear to be disadvantaged in the MELD era, and second, why do black patients continue to be list for liver transplantation with more advanced disease than white patients?"
"It is critical that the public has confidence in our organ allocation system, and I feel that this study sends an important message," says Dr. Andrew Muir, a hepatologist at Duke and the senior author of the study. "MELD has been helpful in easing racial disparities among blacks and whites in liver transplantation, but we are still concerned that African Americans are not listed for liver transplant in the numbers we would expect to see, based upon their prevalence of disease."
Other members of the research team include Carla Brady, Jeffrey Johnson, Alastair Smith and Janet Tuttle-Newhall.