Study says weight-loss surgery lowers risk of liver disease

One in 4 American adults has fatty liver disease caused by obesity, not drinking, and there is no medical treatment for it. Doctors say the only way to keep it in check is to lose weight and eat a healthier diet.

Now, a new study reports bariatric surgery, in addition to helping with weight loss, can protect the liver. The findings were striking: Of a group of more than 1,100 patients who had an aggressive form of fatty liver disease, those who had weight loss surgery cut their risk of advanced liver disease, liver cancer or related death by almost 90 percent over the next decade.

Only 5 of the 650 patients who had bariatric surgery later developed one of those severe liver outcomes, compared with 40 of 508 patients who did not have the procedure.

The weight loss surgery patients were also at significantly lower risk for cardiovascular disease, a finding that is consistent with earlier research. They were 70 percent less likely to experience a cardiac event, stroke or heart failure, or to die of heart disease, according to the study published Thursday in JAMA.

Dr. Ali Aminian, director of the Cleveland Clinic’s Bariatric and Metabolic Institute and the study’s lead author, said in all likelihood weight loss had stopped the disease in its tracks.

“Obesity is the main driver of the fatty liver; it all starts with obesity,” Aminian said. “When we have excess fat that accumulates in the liver, it causes fatty liver. Then inflammation comes and gets worse, and then scar tissue forms and leads to cirrhosis.

“When a patient loses weight, fat goes away from everywhere, including the liver; inflammation subsides, and some of the scar tissue can reverse and get better,” Aminian continued. “Weight loss is the main factor here.”

The results were remarkable, said Dr. Steven Nissen, chief academic officer of the Heart and Vascular Institute at the Cleveland Clinic and the study’s senior author.

The post-surgical disease result “was the lowest I’ve seen in 30 years of doing studies, an 88 percent reduction in progression to advanced liver disease,” he said.

The observational study reviewing cases at the Cleveland Clinic over 12 years did not establish a causal link to lower risks of severe liver or heart conditions from weight loss procedures, but the findings add to mounting evidence that bariatric surgery can provide health benefits beyond weight loss. About 100 million American adults are dangerously obese; around 250,000 undergo bariatric operations each year.

The surgery carries serious risks, however. Sixty-two of the 650 weight-loss surgery patients in the study group developed serious complications after the operation, and four of them died within a year of having the operation.

The new study is also not definitive. It was a retrospective observational study that compared the long-term outcomes of 650 bariatric surgery patients with 508 closely matched patients who did not have surgery. As such, it was not a randomized controlled trial of the kind considered the gold standard in medicine, which randomly assigns patients with similar characteristics to either an intervention arm or a placebo.

Several of the paper’s 16 authors consult or receive research funding from companies that make devices used in weight loss surgery. They did not receive outside funding for this study, however.