From the AGA Journals

Liver transplant exceptions deserve fresh look

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Many criteria are not strictly followed

This study is an important reminder of the need for ongoing evidence-based revision of the MELD-based liver allocation system. It has been clear since the adoption of MELD for the purpose of organ allocation that there are patients for whom the laboratory components of the MELD score do not accurately portray their disease-associated risk of death. Thus, there is widespread petitioning for MELD exception points for a number of conditions, including hepatopulmonary syndrome (HPS). While criteria for some such conditions are clearly defined, most prominently including hepatocellular carcinoma, for most other conditions practices vary by region and criteria are not always strictly adhered to.

The initial number of points granted for most conditions, including HPS, is arbitrary rather than based on objective analysis. This study suggests that while posttransplant outcomes are similar between patients with HPS exception points and those without points, pretransplant survival is superior in the HPS group, suggesting that perhaps a lower MELD score should be assigned to these patients.

While exceptions are currently a fundamental part of MELD-based liver allocation, greater standardization of MELD exception point criteria is urgently needed. Additional analysis of wait list survival and survival benefit models will be required to ensure that individual groups of patients are not being unjustly overprioritized.

Dr. Elizabeth C. Verna is assistant professor of medicine, Center for Liver Disease and Transplantation, Division of Digestive and Liver Diseases, Columbia University College of Physicians and Surgeons, New York. She disclosed no conflicts of interest.



Room air hypoxemia was associated with greater post–liver transplant mortality in hepatopulmonary syndrome patients, according to Dr. David S. Goldberg and his colleagues.

On the other hand, HPS transplant candidates had overall decreased pretransplantation mortality compared with non-HPS patients, suggesting that "current exception policy might overprioritize waitlisted HPS patients," they wrote.

The report appears in the May 1 issue of Gastroenterology (doi:10.1053/j.gastro.2014.01.005).

Dr. Goldberg of the University of Pennsylvania, Philadelphia, looked at all 973 liver transplant candidates from the United Network for Organ Sharing database who had at least one exception application for HPS approved between Feb. 27, 2002, and Dec. 14, 2012.

For comparison, the authors assessed 59,619 non-HPS adult waitlist candidates who registered for their first liver transplantation on or after Feb. 27, 2002.

Overall, there was a 1-year posttransplant survival rate of 91%, a 3-year survival rate of 81%, and a 5-year rate of 76% among the HPS cohort, the authors wrote. Those rates were comparable with the 1-year, 3-year, and 5-year posttransplant rates for non-HPS patients of 89%, 81%, and 74%.

However, looking at pretransplant survival, the authors found that a significantly greater proportion of non-HPS transplant candidates died on the waitlist, compared with HPS patients (20% vs. 9%; P less than .001). That translated to a hazard ratio of 0.82 among HPS patients for dying on the waitlist, compared with non-HPS patients (95% confidence interval, 0.70-0.96).

Next, the authors assessed the relationship between pretransplant room air oxygenation among HPS patients on posttransplant survival rates. They found that patients with pretransplant PaO2 (partial pressure of oxygen in arterial blood) levels of less than 50 mm Hg had a significantly higher posttransplant mortality, compared with patients with PaO2 levels between 50 and 59 mm Hg (HR = 1.56; 95% CI, 1.02-2.38).

Similarly, in a cubic spline model, transplant recipients with a PaO2 of less than 44.0 mm Hg had significantly increased posttransplantation mortality compared with recipients with a PaO2 of 44.1-54.0 mm Hg (HR = 1.58; 95% CI, 1.15-2.18).

"These data must be taken in context, as the 5-year posttransplantation patient survival in HPS patients with the lowest values of PaO2 is still at or above a threshold many would consider acceptable for a transplant recipient," the authors cautioned. "Therefore, the transplant community must decide what degree of hypoxemia makes a patient too high risk," they added.

The authors conceded several limitations. "First, we were unable to employ the strict criteria defining HPS used in prospective multicenter studies," they wrote.

"However, we are confident that most, if not all, of the patients had HPS based on the data documenting hypoxemia and shunting in nearly 90% of patients."

Nevertheless, "excellent posttransplantation outcomes in those with less severe hypoxemia suggest that it might be possible to optimize posttransplantation outcomes for patients with HPS without disadvantaging the broader transplant population," they wrote.

This could be accomplished by a review of current exception algorithms, and "by decreasing the initial number of exception points for HPS patients, while offering additional priority to those whose PaO2 values decline toward higher-risk values," they wrote.

Given the fact that this would increase the overall waitlist time, "an increase rather than decrease in data collected regarding these patients is needed to guide policy," they concluded.

The authors disclosed no conflicts of interest. Dr. Goldberg reported receiving funding from the National Institutes of Health, and the study was partially supported by the Health Resources and Services Administration.

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