ILTS 2012 Report – Risk-assessment scoring system may be helpful in predicting success in cardiac-death donor cases

by  Thomas R. Collins – A recently unveiled scoring system for evaluating the likelihood of post-liver transplant survival is useful in predicting success in transplants from donors with cardiac deaths, a Swiss researcher said here at the 18^th International Congress of the International Liver Transplantation Society.

The Balance of Risk, or BAR, score was unveiled last year and found that the six strongest predictors of post-transplant survival were the recipients MELD (model for end-stage liver disease) score, cold ischaemia time, recipient age, donor age, previous transplant and life support dependence.¹

The BAR score range is 0 to 27, and it was found that the threshold of increasing mortality after transplantation was a score of 18, after which there was a sharp spike in deaths after a year. That finding was later validated in an evaluation of nearly 12,000 cases, for which results are scheduled to be published later this year.

“Below BAR 18, mortality remained at or below 20 percent,” said Phillip Dutkowski, PhD, of the Department of Visceral and Transplantation Surgery at University Hospital Zurich. “But it exponentially increased above BAR 18.” In other risk-scoring systems, mortality tends to increase in a linear fashion as the scores rise, he noted.

Researchers also found that morbidity, measured by number of days in the hospital, increased markedly with a BAR score of 9. So they established three risk classes: low-risk (BAR of 0 to 9); intermediate risk (BAR of greater than 9 but less than or equal to 18); and high-risk (BAR of higher than 18).

In the original BAR study, cases of donation after cardiac death were excluded, along with living donor cases, and partial or combined donation cases.

The researchers have now turned to trying to use BAR scores to predict success in cases with additional risk factors, including cases of a graft from a cardiac death donor and donors with macrosteatosis, a condition involving fat in the liver.

They determined that in cases with those additional risk factors, transplants should only be done in a low-risk situation, with BAR scores of 0 to 9.

In the low-risk BAR class, after five years, transplants from brain-death donors had a cumulative survival rate of 70 percent. Those from cardiac-death donors (with a median warm ischaemia time of 14 minutes) had a rate of 58 percent.

But in the intermediate BAR class, brain-death donor transplants had a cumulative survival rate of 63 percent, compared to just 45 percent for those in the cardiac-death group.

Results were even worse in the high-risk BAR class, with cardiac-death donor cases having a cumulative survival rate of about 40 percent after 2 years.

Similar results were seen in cases involving donors with macrosteatosis, researchers found.

Researchers also suggested that there may be treatment options available for the cases involving that extra risk. In cases of cardiac-death donors, they suggested machine perfusion of livers with extended warm ischaemia time.

“Liver grafts with additional risk factors, for example DCD grafts or more than 30 percent macrosteatic livers,” Dr Dutkowski said, “should be implanted, therefore, in low-risk situations.”

 

Reference:

1. Dutkowski et al. Ann Surg 2011; 254 (5)