ILTS 2016: Risk of living donor transplants can be mitigated: Dr Leslie Lilly (Transplant Hepatologist, UHN Toronto General Hospital, ON, Canada). Also included associated article.

Risk of living donor transplants can be mitigated

by Thomas R. Collins

Making living donor transplants less risky through new and innovative approaches is the best way to deal with the risk that comes with trying to expand the donor pool in this way.

Chung-Mao Lo, MD, PhD, Head of the Department of Surgery and Chair of Hepatobiliary Surgery at the University of Hong Kong, gave a vivid example of how it might be possible to greatly reduce risk with advancements in knowledge and expertise.
A generally accepted rule is that a liver graft should have a volume that is at least 40% of the standard liver volume for a given recipient’s size. Using this 40% guideline, researchers at his centre found, about 6% of live donors could donate their left lobe — a goal because using the smaller left lobe involves five times less risk of donor mortality than using the larger right lobe.
In a study at his centre, grafts that were 35% of this standard volume, considered “small” grafts, had a survival rate that was not statistically different from larger grafts.
Using that guideline for graft volume, researchers there also found, the percentage of left lobes that could be used increases to 12.5% — more than doubling the availability of left lobes.
If, through innovation and refinement of transplantation techniques, that number could go down to 30% of the standard liver volume, then it would more than double again, to 29% of left lobes able to be used.

“If we can come down to 25%, in fact,” Dr. Lo said, “our data show that perhaps even 60% of living donor transplants can be performed using a left liver graft.”
At a recipient survival rate of 90%, 180 recipient lives would be saved for every donor death using right lobes.
But, Dr. Lo said, “if you are using a left liver, one donor death will actually save 900 recipients. That’s a much better risk-benefit analysis.”
Assessing the risk of living donation and deciding what is acceptable is a complicated process that is specific to individual countries. In Japan, Hong Kong, South Korea and India, the great majority of liver transplants are done using live donors, although the number of deceased donor transplantations is increasing.
But in Europe and the U.S., living donations make up less than 5% of transplants, because the quality of living donor grafts is seen as marginal and because of different MELD priorities in the West.
Because of the number of deceased donor liver donations in the West, there is less need for living donations. But Dr. Lo offered a reminder that, in cases where there is tremendous need, not accepting more risk can be the worst option.

 

“If we avoid every potential risk, then there is the risk of doing nothing,”he said. “And in this situation, it’s the death of our patients who are waiting for transplantation.”
At his centre, improvements have been seen over time. With their first 50 living donor transplants of the right lobe, the major complication rate was 14%, compared to 6% for the next 50. Minor complications dropped from a rate of 26% to 8% from the first 50 to the next 50. Two-year graft survival improved from about 70% to about 90%.

 

“The learning curve is very important,” Dr. Lo said. “You have to continuously improve your skill.”
Lowering the risk might be possible, but the level that’s acceptable to a given person or centre is still not a straightforward question, he said.

 

“We have a lot of variations in trying to define the acceptable risk for our living donors and liver transplantation,” he said. “Obviously it varies between countries, between centres, and actually between clinicians. But of course even though we try to define these acceptable criteria, eventually there are the donors and the recipients who decide whether to accept it.”

 

“In terms of risk management,” he said, “risk mitigation is definitely better and we should do the mitigation by innovation.”

 

References

 

Chan SC, Fan ST, Chok KS, et al. Increasing the recipient benefit/donor risk ratio by lowering the graft size requirement for living donor livertransplantation. Liver Transpl. 2012 Sep;18(9):1078-82.

Lo CM, Fan ST, Yong BH, et al. Lessons learned from one hundred right lobe living donor liver transplants. Ann Surg. 2004 Jul;240(1):151-8.