Liver Damage Attenuated by Bariatric Surgery: New Treatment of Choice?

Thirty percent of Americans currently meet obesity criteria, and potentially qualify for bariatric surgery. These were among the opening facts on the obesity epidemic offered by University of South Florida bariatric surgeon Michael Murr, MD, as he began his discussion at Digestive Disease Week 2014. We often hear the negatives about bariatric surgery: it’s expensive, and some patients have had serious side effects, especially in the early years of the procedure. Dr. Murr’s perspective is different-his starting point in this study is that obese individuals are at risk for fatty liver disease and subsequent hepatic fibrosis, in addition to the metabolic and cardiovascular complications more commonly studied. Is there anything to do about it? Specifically, does bariatric surgery have an impact?

This study is the first to suggest the value of bariatric surgery in reversing non-alcoholic fatty liver disease (NAFLD) and fibrosis in obese persons-so for the first time, we have evidence that this procedure may help prevent chronic liver disease.

In this retrospective study, a blinded pathologist reviewed paired liver biopsies of 152 patients (82% women) who underwent bariatric surgery and had subsequent abdominal surgery between 1998 and 2013. The baseline biopsy had been taken intra-operatively during the bariatric procedure, and the post-procedure biopsy was taken in patients who underwent subsequent abdominal surgery sometime during the study period. The average post-surgical duration before biopsy was 29 months.

The biopsies revealed that steatosis (fatty deposition) resolved in 70% (82/118); lobular inflammation resolved in 74% (46/62); chronic portal inflammation resolved in 32% (32/99) and steatohepatitis resolved in 88% (44/50). Fibrosis of any grade resolved in 21% and improved in another 23% of patients. Specifically, Grade 2 fibrosis was present in 52 patients pre-op; 16 (31%) resolved, 16 (31%) improved, and 15 (29%) did not worsen post-op. Of the 10 patients with bridging fibrosis (Grade 3), one resolved and seven improved. In total, Grade 2 or 3 fibrosis improved in 65% of all patients who had it. Cirrhosis improved in one of three patients who had it before surgery.

The study’s primary limitation is its retrospective nature and the fact that patients were selected for inclusion and follow-up liver biopsy only if they had indications for a second abdominal surgery, which introduces selection bias that cannot be corrected for. Still, the authors are confident enough of their results to suggest that bariatric surgery should be considered the treatment of choice for non-alcoholic fatty liver disease in obese patients. If adopted, that would mean a shift in current guidelines, which recommend bariatric surgery for all persons with a BMI of 40 or greater, and for those with a BMI of 35 or greater in the setting of obesity comorbidities. Dr. Murr is unequivocal: he suggests that NAFLD be added to the list of obesity comorbidities that would justify performance of the procedure at the lower BMI threshold. “We are in the midst of an obesity epidemic that could lead to an epidemic of nonalcoholic fatty liver disease,” said Dr. Murr.