To determine how BMI influences the survival benefits from liver transplantation, researchers – led by Shawn J. Pelletier, M.D., assistant professor in the Department of Surgery at the University of Michigan Medical School – conducted a retrospective study of all 25,647 adult patients listed for liver transplantation in the U.S. between Sept. 1, 2001 and Dec. 31, 2004.

The patients were classified by BMI in the following way: underweight (BMI<20); non-obese (BMI 20<25); overweight (BMI 25<30); obese (BMI 30<35); severely obese (BMI 35<40) and morbidly obese (BMI>40). The researchers compared outcomes for patients within these groups after adjusting for age, gender, race, ascites status, diagnosis and Model of End-Stage Liver Disease (MELD) score.

“Our study demonstrates a clear survival benefit for liver transplant recipients when compared to their counterparts on the waiting list, regardless of BMI,” the authors report.

Furthermore, no group showed a significant difference in post-transplant mortality risk compared to the group with a normal BMI, in contrast to the findings of previous studies.

For candidates who remained on the waiting list throughout the study period, there was also no significant difference in mortality risk among the BMI groups, except for underweight patients, who were 61 percent more likely to die, compared to those with a normal BMI.

“Our study found that obese patients, when compared to patients with normal BMI have a similar risk of death while on the liver transplant waiting list, have similar survival rates following liver transplantation, and have a similar reduction in the risk of death,” say the authors, who suggest that the AASLD recommendation regarding morbidly obese patients be reconsidered.

“Unlike previous studies, this study did not identify an increase in mortality for obese patients undergoing liver transplant, including morbidly obese patients. In contrast, underweight liver transplant recipients were identified to be at an increased risk of death. However, all categories of BMI demonstrated a significant survival benefit when compared to their counterparts on the waiting list. Therefore, BMI alone should not necessarily exclude patients with end-stage liver disease from access to liver transplantation,” the authors conclude.

An accompanying editorial by Paul Thuluvuth confirms that “it is clear from this study that morbidly obese patients benefited from liver transplantation.” However, he says, the shortage of organs mandates that these precious resources be used in a more judicious manner.

Because many other studies indicate that obese patients do not fare as well after transplantation, and because morbid obesity is a surrogate marker of other serious co-morbidities like vascular disease, diabetes, hyperlipidemia, he concludes that “morbidly obese patients with one or more other serious co-morbidities should not be offered liver transplantation. This process will allow us to offer liver transplant in a ‘selective’ manner to some morbidly obese patients, and thereby assuring a low morbidity and better long-term survival. That should be our goal,” he says.

Article: “Effect of body mass index on the survival benefit of liver transplantation.” Pelletier, Shawn; Schaubel, Douglas; Wei, Guanghui; Englesbe, Michael; Punch, Jeffrey; Wolfe, Robert; Port, Friedrich; Merion, Robert. Liver Transplantation; December 2007; (DOI: 10/1002/lt.21183).

Editorial: “Morbid obesity with one or more other serious comorbidities should be a contraindication for liver transplantation.” Thuluvath, Paul. Liver Transplantation; December 2007; (DOI: 10.1002/lt.21211).