medwireNews: US researchers have found that the expansion of liver transplantation criteria to include post-cardiac death donors (DCD) is associated with an increase in the proportion of unused donor livers.
The authors and commentators say that the findings herald a decline in transplant availability in years to come, as donation rates stagnate.
Eric Orman (University of North Carolina, Chapel Hill, USA) and colleagues used data from all organ donors in the USA since 1988, as liver nonuse in this population is likely due to specific issues with the liver.
Between 1988 and 2004, both the number of unused livers and the proportion of donors whose liver was unused declined. However, since 2004, the number of unused livers rose from 841 to 1345 in 2010, and the proportion of donors with unused livers rose from 15% to 21%.
Had the rate of nonuse remained stable after 2004, the authors calculate that 382 more livers would have been transplanted in 2010.
Multivariate analysis showed that DCD was the factor most strongly associated with liver nonuse. The odds of a DCD liver being unused rose nearly fourfold between 2004 and 2010 from 5.53 to 21.31, respectively, relative to donors aged under 30 years. In 2010, DCD accounted for 28.2% of unused livers.
Older donor age, higher body mass index, and diabetes are also independently associated with liver nonuse.
The criteria for liver donation were expanded to include older donors, donors with fatty livers, and DCD donors to increase availability. However, the authors explain that while this may initially have contributed to decreasing liver wastage before 2004, transplant centers' concerns about the quality of these livers appear to have prevailed.
"Tolerance for worse outcomes with extended criteria donor livers has probably reached a limit, and this has led to declining utilization since 2004," they write in Liver Transplantation.
In an accompanying editorial, Neehar Parikh and Anton Skaro of Northwestern University, Chicago, USA, say that changes are needed to prevent future shortages of donor livers.
"If these trends continue, we can expect persistently lower rates of donation in the coming years unless either a lower threshold of organ quality is broadly implemented or other avenues of donor pool expansion are developed."
"The regulatory oversight of DCD liver transplantation should be modified to encourage the utilization of higher risk DCD grafts in recipients for whom these risks are tempered against poor wait-list outcomes," they conclude.
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