No Thumbs Down on Liver Graft for Morbidly Obese


ANN ARBOR, Mich., Dec. 5 -- Severe obesity alone should not rule out a liver transplant, according to researchers here.
Action Points --->
Explain to interested patients in this retrospective study that post-transplant survival for severely obese patients on a liver transplant waiting list was similar to that of normal-weight patients on the list.
Explain that morbid obesity with one or more other serious comorbidities may be a contraindication for receipt of this rare resource.
Compared with patients with a normal BMI on a waiting list, obese patients have a similar risk of death while waiting and similar survival rates after transplantation, Shawn J. Pelletier, M.D., of the University of Michigan, and colleagues reported in the December issue of Liver Transplantation.
However, in an accompanying editorial, Paul J. Thuluvath, M.D., of Johns Hopkins, qualified the recommendation, noting that one or two more serious comorbidities should be a contraindication for a transplant.
With the increase in obesity in the U.S., patients with end-stage liver disease are more likely to be obese and about 20% have a BMI over 40, the researchers wrote. Because previous studies have shown that these patients have a higher risk of morbidity and mortality after transplant, the American Association for the Study of Liver Diseases has recommended that morbid obesity should be a contraindication for transplant.
However, the Michigan investigators said, no studies have considered the survival benefit for patients given a graft compared with those not given one.
They researchers conducted a retrospective cohort study of 25,647 liver transplant candidates who were initially wait-listed from September 2001 through December 2004 and identified in the Scientific Registry of Transplant Recipients database.
Adjusted Cox regression models were fitted to assess the association between BMI and liver transplant survival (post-transplantation versus waiting list mortality). Of the patients on the waiting list, two-thirds were men (mainly age 40 to 59), and 44,488 (17%) received a transplant by Dec. 31, 2004.
The cause of liver disease for these patients included acute hepatic necrosis, cholestatic and noncholestatic cirrhosis, and other conditions, as well as nonalcoholic steatohepatitis.
Patients were classified in six groups on the basis of BMI: underweight (BMI <20 kg/m2), normal weight (20 to <25), overweight (25 to <30), obese (30 to <35), severely obese (35 to <40), and morbidly obese (≥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.
At wait-listing and transplantation, similar proportions were morbidly obese (BMI ≥40, 3.8% versus 3.4%, respectively) and underweight (BMI <20, 4.5% versus 4. respectively).
Underweight patients had a significantly higher covariate-adjusted risk of death while on the waiting list (hazard ratio [HR]: 1.61, P<0.0001) compared with normal-weight candidates. However, after transplantation the underweight recipients had a similar risk of death (HR: 1.28, P=0.15) as normal-weight recipients, the researchers reported.
For candidates who remained on the waiting list throughout the study period, there was also no significant difference in the mortality risk among the BMI groups, except for underweight patients, often malnourished, who were 61% more likely to die compared with those with a normal BMI.
Compared with patients on the waiting list with a similar BMI, all subgroups of liver transplant recipients demonstrated a significant (P<0.0001) survival benefit, including the morbidly obese and underweight recipients. For example, hazard ratios were 0.14 for the underweight group, 0.17 for normal BMI (20 to <25), 0.16 for BMI 35 to <40), and 0.15 for BMI ≥40).
Some study limitations mentioned were the fact that assessing BMI in these patients may not reflect the true extent of obesity, inasmuch as may patients also have peripheral edema or ascites, which could affect weight.
In addition, the study population included only those patients deemed suitable for being wait-listed for transplantation. Thus, some patients with either a high or a low BMI may have been denied access to the waiting list and would not have been included in this analysis because of other unmeasured adverse factors.
In his editorial, Dr. Thuluvath said it is clear that these obese patients benefited from liver transplantation. However, he added, 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 comorbidities, the shortage of organs mandates that these precious resources be used in a more judicious manner.
Thus, he said, morbidly obese patients with one or more serious comorbidities such as uncontrolled hypertension, micro- and macrovascular complications, diffuse coronary artery disease, previous MI or stroke, or significant microalbuminuria should not be offered liver transplantation, he said.
This process, he added, "will allow us to offer liver transplantation in a 'selective' manner to some morbidly obese patients, thereby assuring a low morbidity and a better long-term survival."
Drs. Pelletier and Thuluvath reported no financial conflicts.
The Scientific Registry of Transplant Recipients is funded by the Health Resources and Services Administration, U.S. Department of Health and Human Services. The views expressed herein are those of the authors and not necessarily those of the U.S. government. The statistical analysis was supported by a National Institutes of Health grant to two of the study authors.
Primary source: Liver TransplantationSource reference:Pelletier S, et al "Effect of body mass index on the survival benefit of liver transplantation" Liver Transpl 2007; 13: 1678-1683. Additional source: Liver TransplantationSource reference: Thuluvath PJ, "Morbid obesity with one or more other serious comorbidities should be a contraindication for liver transplantation" Liver Transpl 2007; 13: 1627-1629.