The Surprising Relationship Between BMI and Liver Transplantation Mortality

Many transplant programs decline liver transplantation (LT) to obese candidates because they have a higher risk of surgical complications and death than do non-obese candidates. In addition, obese candidates have longer waiting times for LT. However, studies examining the association of a recipient’s body mass index (BMI) and post LT-mortality have not produced consistent results.

In a recent study by Washington University researchers, re-examination of the relationship between BMI and post LT-mortality revealed what is termed an obesity paradox: a group of obese patients had the best survival outcome after transplantation.

Su-Hsin Chang, PhD

Assistant Professor Su-Hsin Chang, PhD, Division of Public Health Sciences, Department of Surgery and Assistant Professor of Medicine, Tarek Alhamad, MD, Division of Nephrology, in collaboration with other Washington University researchers and transplant surgeons, looked at mortality after LT in 48,226 patients undergoing LT between 2002 and 2013 (Organ Procurement and Transplantation Network database). The study was the first to analyze such data after the institution of the MELD (Model for End-Stage Liver Disease) system, which helps determine the severity and extent of liver disease. Higher MELD scores reflect more severe liver disease.

Tarek Alhamad, MD

The study found that patients with a BMI of within the range of 28–37 (average of about 34), with lower MELD scores, had the best survival outcome after transplantation. A person with a BMI > 30 is considered to be obese.

This obesity paradox in which obesity is associated with lower overall mortality has also been found in older people or in people with other severe health conditions such as hemodialysis, heart failure and cancer survivors. This paradox is attributed to the fact that weight loss is associated with disease progression and that people with higher BMI tend to have better tolerance to treatment, thus survival is improved.

The researchers stress that their conclusions are not intended to encourage obesity. After all, obese patients after LT do have a higher chance of death from multi-system organ failure and cardiovascular events. However, their findings suggest that once obese people develop liver disease, progress to a more advanced liver disease, and become wait-listed for LT, maintaining a high BMI may be beneficial to their overall survival after LT.

This finding has the potential to affect current practices and policies of many transplant programs, which refuse to transplant a patient with obesity. This is particularly consequential considering that in the United States, more than 1 in 3 adults are considered to be obese.

The article Re-examining the Association of Body Mass Index With Overall Survival Outcomes After Liver Transplantation, published in the journal Transplantation Direct, can be read in full here.
Authors: Su-Hsin Chang, PhD, Xiaoyan Liu, MS, Nils P. Carlsson, BS, Yikyung Park, ScD, Graham A. Colditz, PhD, Jacqueline M. Garonzik-Wang, MD, William C. Chapman, MD, Jason R. Wellen, MD, Maria B. Doyle, MD, and Tarek Alhamad, MD.