Clinical

Extreme BMI ups mortality risk in liver recipients

Last Updated: 2009-08-14 13:05:18 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Liver transplantation "holds increased risk" for adults at the extremes of body mass index (BMI), according to findings published in the August issue of Liver Transplantation.

"Patients undergoing liver transplantation who are underweight or very severely obese experience significantly higher rates of morbidity and mortality in comparison with patients in the middle BMI categories," Dr. Andre A. S. Dick, of the University of Washington Medical Center, Seattle, and colleagues write.

The research team investigated the impact of pre-transplant BMI on patient survival by reviewing data from the United Network for Organ Sharing on 71,446 liver transplants performed in adults from 1987 through 2007.

Patient survival was analyzed for three eras: 1987-1992, 1993 to February 2002 (10 years before use of the MELD donor liver allocation system), and March 2002 to 2007 (after institution of MELD).

Patients with BMI < 18.5 kg/m2 were classified as underweight, patients with BMI of 40 or greater were classified as very severely obese, and everyone in between served as controls. The number of transplants performed in each group was 1827, 1447, and 68,172, respectively.

In each of the three eras, "multivariable analysis showed that underweight and very severe obesity were significant predictors of death," Dr. Dick and colleagues note.

Underweight patients were more likely to die from hemorrhagic complications or cerebrovascular accidents, compared to the control group.

The very severely obese group had higher rates of death from infectious complications and cancer.

The authors point out that patients at the extremes of BMI had costlier care, with more ICU services and longer hospital stays. They add, "A transplant program taking care of these patients must be aware of the increased cost."

Also, they point out, if very severely obese patients are required to lose weight before transplantation, the time necessary for this process can result in higher MELD scores. Instead, they suggest, "it might be better to perform transplantation with a higher BMI but a lower MELD score....the very severely obese patients in our study....had significantly better survival rates when transplanted at a lower MELD score."

For critically ill underweight patients, on the other hand, "radically new developments are needed to improve survival."

"Further research in the areas of obesity, bariatric surgery, nutrition, and immunosuppressive management will hopefully bring further insights into the transplant care of these difficult-to-manage patients," the researchers conclude.

Liver Transpl 2009;15:968-977.