Bariatric Surgery Improves Nonalcoholic Fatty Liver Disease

Caroline Helwick

May 04, 2014

CHICAGO — Bariatric surgery may not only lead to weight loss and better metabolic profiles, it can also improve nonalcoholic fatty liver disease (NAFLD), according to the results of a new study.

"What we found surprised us," said senior author Michel Murr, MD, professor of surgery and director of Tampa General Hospital and University of South Florida Health Bariatric Center.

"Bariatric surgery reduced fat deposits in the liver, and it also resolved liver inflammation and reversed early-stage liver fibrosis and scarring," he reported.

"These findings suggest that bariatric surgery should be considered a treatment of choice for NAFLD patients with a body mass index (BMI) more than 35 kg/m² and obesity-related comorbidities, or a BMI more than 40 kg/m²," said Dr. Murr.

The results of the study were presented here at Digestive Disease Week (DDW) 2014.

In a press briefing prior to DDW 2014, Dr. Murr called attention to the current obesity epidemic. One in 3 Americans ie obese, he said.

"Bariatric surgery has become lifesaving for many, as this procedure is linked to improvements in obesity-related conditions. We were building on that trend by looking at bariatric surgery's effect on NAFLD," said Dr. Murr.

The study compared paired biopsy specimens for 152 patients (82% women; mean age, 46 years) taken before surgery and an average of 29 months after surgery. The mean preoperative BMI was 52 kg/m², and the mean excess body weight loss was 62% at the time of subsequent biopsy. The type of surgery was gastric bypass for the majority.

A blinded pathology review identified patients with cellular-level manifestations of NAFLD — fat deposits and inflammation of the liver — on preoperative biopsy.

Table: Improvements After Bariatric Surgery

Preoperative Condition Resolved Improved Remained Stable
Steatosis (n = 118) 70%    
Lobular inflammation (n = 62) 74%    
Chronic portal inflammation (n = 99) 32%    
Steatohepatitis (n = 50) 88%    
Grade 2 fibrosis (n = 52) 31% 31% 29%
Grade 3 bridging fibrosis (n = 10) 10% 70%  
Cirrhosis (n = 3)   33%  


The reversal of fibrosis applied only to early-stage, not late-stage, fibrosis.

Study researchers believe that the underlying mechanism for these improvements is related to the weight loss the patients achieved.

"We have a lot of laboratory research about fatty liver, weight loss, and surgical weight loss in small animals, and what appears critical is the intervention to reduce the inflammation in the liver, which can happen from weight loss. More important, we found that the liver goes from an organ that stores fat to one that burns fat after bariatric surgery," explained Dr. Murr.

We think that with bariatric surgery, we can impact the prognosis of NAFLD and its natural history. Dr. Michel Murr

"The findings of our study are especially relevant for patients who have a low success rate with traditional interventions, such as medication and dieting," he added. "We think that with bariatric surgery, we can impact the prognosis of NAFLD and its natural history."

Future research will involve molecular "fingerprinting," said Dr. Murr. "We have a few genes of interest, and we want to drill down and understand which are turned off or on, specifically those affecting the progression of liver fibrosis." Such knowledge could inform drug discovery.

Ibrahim Hanouneh, MD, a hepatologist at the Cleveland Clinic, commented on the findings for Medscape Medical News.

"The current best treatment of NAFLD and nonalchoholic steatohepatitis is weight reduction. Lifestyle modifications through appropriate nutrition and increased physical activity, with or without pharmaceuticals, have been disappointing. Bariatric surgery is accepted as a treatment for obesity and results in better control of metabolic factors, including diabetes, than does medical therapy alone," he said.

"Adding to its advantages, the current study showed that bariatric surgery improves liver histology in severely obese patients and is associated with resolution of steatosis or steatohepatitis in the majority of patients. Interestingly, advance hepatic fibrosis resolved or improved in 65% of patients," he emphasized.

"These are exciting results. In my opinion, bariatric surgery should be considered as a treatment for nonalchoholic steatohepatitis in severely obese patients."

Dr. Taitano, Dr. Murr, and Dr. Hanouneh have disclosed no relevant financial relationships.

Digestive Disease Week (DDW) 2014. Abstract 233. Presented May 4, 2014.


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