Jan 11 (Reuters) - The number of donor livers thrown away in the United States has increased since 2004 due in part to a population growing older and heavier, though changes in medical practice may also make some donor livers less viable, according to a U.S. study.
"The rationale for looking at this question in the first place is that the number of liver transplants done in the U.S. has gone down," said Eric Orman, the study's lead author and a fellow at the University of North Carolina at Chapel Hill.
To identify factors that might explain the trend, Orman and his colleagues used a national database of all organ donations beginning in late 1987 to see how many livers from donors of at least one organ were discarded, and why.
They found that the proportion of unused livers fell dramatically, from 66 percent in 1988 to 15 percent in 2004. But after that, the percentage of unused livers began to rise again, hitting 21 percent in 2010.
Between 1988 and 2010, about 107,000 donated their livers. Nearly 42,000 of these were after 2004. Of those post-2004 donations, about 33,900 livers were used and about 7,600 livers were not.
When the researchers, who published their findings in the journal Liver Transplantation, looked at the differences between the livers that were used and those that weren't, they found a few possible links.
Specifically, livers from older, heavier and sicker patients were more likely to be thrown out between 2004 and 2010.
"That wasn't too surprising because a lot of those donors are more likely to have fatty livers," said Orman. "Those livers are avoided because they can lead to worse outcomes after transplant."
The proportion of older, heavier donors also increased during the study period.
Between 1988 and 2010, the average donor age rose by almost 10 years, and the proportion of donors who were over age 50 grew from 16 percent to 38 percent. The proportion who were obese rose from 15 percent in 1995 to just over 30 percent in 2010.
Donors with diabetes and high blood pressure grew from three percent in 1995 to almost 23 percent in 2010.
The findings suggest that overall population aging and rising obesity led to a decline in the quality of livers being harvested, and ultimately to an increase in the percentage of unused organs, the researchers wrote.
They also found that the number of livers donated after so-called cardiac deaths rose during the study period, and that those livers were more likely not to be used.
In traditional donations after brain death, the body's heart is still pumping and supplying blood to organs because it's attached to life-support machines. After cardiac death, those machines have been disconnected.
Livers donated after cardiac death have sometimes been linked to worse outcomes after transplant, so the fact that more were discarded did not come as a surprise.
The researchers also found that cardiac death livers made up a quarter of all unused livers by 2010, whereas in 1995 they were just one percent. SOURCE: http://bit.ly/VVvzs4I
(Reporting by Elaine Lies)