Thursday, May 24, 2012

DDW-Many Livers 'Too Fat' For Transplant

• Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
• Increases in factors associated with fatty liver disease may be leading clinicians to discard more donated livers.
• Point out that over the past few years there's been a decline in the number of liver transplants done, but that decline isn't explained by flat donation rates alone.

In an analysis of data from the United Organ Sharing Network (UNOS), age, obesity, diabetes, and hypertension were associated with an increased risk of a liver being discarded, Eric Orman, MD, of the University of North Carolina at Chapel Hill, and colleagues reported during a press briefing at Digestive Disease Week here.

"We're actually throwing out livers that in the past may have been able to be used ... [because] of all these factors associated with fatty liver disease," Orman explained.

Orman said that over the past few years, there's been a decline in the number of liver transplants done, but that drop isn't explained by flat donation rates alone.

"Although donation rates have decreased overall, they haven't decreased to the same extent as the decline in the number of livers transplanted," he said, adding that one explanation may be an increase in discard rates due to poor quality of organs.

So he and colleagues conducted a retrospective study of data from UNOS between 1994 and 2010 totaling 93,232 organ donors. Living donors, split livers, and donors with a body mass index of less than 14 or more than 50 kg/m were excluded.

Among the nearly 94,000 donors, 75% of livers were transplanted and a quarter of livers were not used.

They found that the number of discarded organs was stable until 2003 (with a total of 1,058 organs discarded in that last year), and then rose to 1,828 by 2010.

In a bivariate analysis, they found that discarded livers more often came from donors who were older (median 49 versus 43 years), obese (35% verses 22% of non-obese donors), diabetic (35% versus 24% of nondiabetics), and hypertensive (31% versus 22% of normotensive patients).

Discard rates were also higher in donation after cardiac death, which is different from standard procurement. In the latter, a patient is declared brain dead but kept on a ventilator to keep the organs perfused (65% versus 22%). In donation after cardiac death, perfusion of blood to the organs is disrupted.

In multivariate analysis, the researchers found that all of the previous factors were associated with a liver being discarded:

  • Age (OR 1.03 for each year increase, 95% CI 1.03­ to 1.04)
  • Obesity (OR 1.92, 95% CI 1.82 to ­2.03)
  • Diabetes (OR 1.42, 95% CI 1.32 to ­1.53)
  • Hypertension (OR 1.15, 95% CI 1.08­ to 1.22)
  • Donation after cardiac death (OR 12.3, 95% CI 11.3 to ­13.4)

The researchers also saw significant increases in median donor age (40 to 46) and the prevalence of obesity (13% to 31%) during the study period, along with significant increases in diabetes (3% to 13%), hypertension (22% to 39%), and donation after cardiac death (2% to 12%).

They estimated that in 2010, 44% of discards were due to increased age, 9% to obesity, 5% to diabetes, and 5% to hypertension. These proportions were stable over time, they said.

On the other hand, the proportion of livers discarded due to donation after cardiac death rose from 0.2% in 2000 to 26% in 2010, suggesting an increasing reluctance to use these grafts, they reported.

Orman said that, overall, the findings are important "because if these trends continue, we're going to see further declines in liver transplant."

Kenneth Andreoni, MD, a UNOS committee member, said the increasing prevalence of comorbidities in donors is a "double-edged sword" because it reflects the fact that public health messages about safety are getting through to younger people, even though that may mean fewer quality donors.

"We're seeing fewer young people dying in traumas, but we're getting less high-quality, excellent organs," Andreoni told MedPage Today. "The question is, how can we make the best use of more middle-age and older donors?"

When it comes to organs with fatty liver disease, some researchers have been trying to better quantify the type of fat in the liver so that surgeons can have a better idea of what's usable and what's not, said Andreoni, who is from Ohio State University in Columbus.

Improvements on the pathology side may also be needed, he said. For instance, pathologists may need to offer a more specific range in terms of the percentage of fat in the organ, so clinicians can more easily recognize if an organ needs to be discarded or not.

Other work has focused on whether there are better ways to protect a fatty liver so it has a better chance of working after it's transplanted. "Is there something you can put in during reperfusion, like an antioxidant, that will lead to better outcomes?" Andreoni said.

A co-author reported a relationship with Salix Pharmaceuticals

Primary source: Digestive Disease Week
Source reference:
Orman ES, et al "The number of grafts available for liver transplantation is decreasing as a result of increasing age, metabolic syndrome, and donation after cardiac death" DDW 2012; Abstract 841.

Kristina Fiore
Staff Writer
Kristina Fiore joined MedPage Today after earning a degree in science, health, and environmental reporting from NYU. She’s had bylines in newspapers and trade and consumer magazines including Newsday, ABC News, New Jersey Monthly, and Earth Magazine. At MedPage Today, she reports with a focus on diabetes, nutrition, and addiction medicine

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