Experts Call for Evaluation of Current Criteria for Allocating Organs for Transplantation
New research shows increasing disparity in mortality among candidates
with and without hepatocellular carcinoma (HCC) who are on the waiting
list for liver transplantation. The study available in the April issue
of Liver
Transplantation, a journal published by Wiley-Blackwell on
behalf of the American Association for the Study of Liver Diseases,
found that liver cancer patients are less likely to die on the wait list
than non-HCC candidates, prompting transplantation specialists to
suggest a reevaluation of current allotment criteria for those with HCC.
In 2002, the United Network for Organ Sharing (UNOS) implemented the
Model for End Stage Liver Disease (MELD) scoring system to prioritize
candidates on the waiting list for liver transplantation in the U.S.
While MELD accurately predicts 90-day waitlist mortality, there are some
candidates with extensive disease symptoms, such as those with HCC, who
need additional prioritizing criteria to assess clinical risk. These
candidates receive MELD exception points, of which HCC patients on the
wait list could gain 22 points based on increased mortality risk,
meaning HCC patients may be transplanted before other patients at
greater risk of death.
“With the scarcity of available livers for transplantation, it is vital
that allocation criteria ensure those candidates at greatest mortality
risk are first to receive a life-saving organ,” said Dr. David Goldberg
with the University of Pennsylvania and lead author of the current
study. “Our study investigated appropriate designation of exception
points for transplant candidates with HCC, comparing mortality risk to
those with similar MELD scores, but without liver cancer.”
The team analyzed data from the Organ Procurement and Transplantation
Network (OPTN) UNOS database, including candidates eighteen years of age
and older who were on the waiting list for liver transplantation between
January 2005 and May 2009. The HCC group was comprised of 6,246
candidates who received exception points for stage two (T2) liver
cancer. These candidates were more likely to be older, male and
Caucasian or Asian compared to those without liver cancer. In the
non-HCC cohort, candidates were categorized by MELD score with 2,564
candidates with a score of 21-23; 4,655 with 24-26; and 2,737 with MELD
27-29.
Analysis shows that within 90 days of listing 4.2% of HCC candidates
were removed from the wait list for death or clinical deterioration
compared to 11% of non-HCC candidates with MELD scores 21-23. For HCC
candidates with 25 exception points (3-6 months wait-time) versus
non-HCC candidates with MELD scores 24-26, close to 5% and 17% were
removed from the waiting list, respectively. Of the HCC candidates with
28 exception points (6-9 months wait-time) 3% were removed for death or
clinical deterioration compared to 24% of non-HCC candidates with MELD
scores of 27-29.
Researchers determined that over time the risk of waitlist mortality or
clinical decline was unchanged for HCC candidates, but increased
significantly for non-HCC candidates. Dr. Goldberg concludes, “Our data
suggest HCC candidates have substantially lower odds of waitlist removal
for death or deterioration than non-HCC candidates, and strongly
indicates that exception points currently allotted for HCC should be
lowered.”
In a related editorial also published this month in Liver
Transplantation, Dr. Patrick Northup from the University of Virginia
agrees and writes, “The Goldberg et al. study adds strength to the
argument that the ‘sickest first’ policy may not be well served by the
current allocation methods for HCC under the MELD system.” He proposes
that the transplantation community strive to develop a more fluid
allocation system that is responsive to new medical evidence. “The
allocation system should be managed as a whole, rather than as isolated
pieces, to ensure patients on the waitlist are prioritized based on the
desire to minimize waitlist mortality.”
