Obese Patients With NAFLD May Have Lower Cirrhosis Risk After Bariatric Surgery

By Lisa Rapaport

April 13, 2020

(Reuters Health) - Patients with nonalcoholic fatty liver disease (NAFLD) who undergo bariatric surgery may be less likely to develop cirrhosis than their counterparts who don't get bariatric surgery, a retrospective analysis suggests.

Using a large insurance database, researchers identified 2,942 patients with NAFLD who underwent bariatric surgery and matched them by age, sex, and comorbid conditions with 5,884 NAFLD patients who did not undergo surgery.

Median follow-up was 32.3 months for bariatric surgery patients and 31.3 months for controls. Kaplan-Meier analysis and Cox proportional hazards modeling were used to evaluate differences in progression from NAFLD to cirrhosis.

Bariatric surgery was associated with a 69% lower risk of developing cirrhosis.

A total of 116 patients progressed to cirrhosis during the study period with 101 events (1.7%) in the nonsurgical population and 15 events (0.5%) in the bariatric surgery cohort. The median time to development of cirrhosis was 49.2 months for bariatric surgery patients versus 35.4 months for nonsurgical patients.

Male gender was associated with an increased risk of cirrhosis (hazard ratio 2.07).

"Surgeons have noted for years that NAFLD and NASH tend to disappear after bariatric surgery, so it makes sense that these patients would have a lower rate of progression to cirrhosis," said coauthor Dr. Adam Sheka of the University of Minnesota in Minneapolis.

"However, cirrhosis takes years to develop, so most studies use surrogate markers (changes on liver biopsy, or changes in lab values) to say that interventions, such as medications or bariatric surgery, have enough of an effect on NAFLD or NASH that they likely prevent cirrhosis," Sheka said by email. "Our study used a large database following patients over a long period of time to show that bariatric surgery in patients with NAFLD appears to be associated with reduced rates of cirrhosis long-term."

The diagnosis of obesity was not a statistically significant predictor of cirrhosis (HR 0.58). Coding patterns in administrative data used for the study may explain this finding, which is not consistent with previous epidemiological studies linking obesity to cirrhosis, the researchers note.

Another limitation is that researchers were unable to extract information on the exact histopathology (NAFLD, NASH, fibrosis) for each patient.

In addition, although alcohol use was a preoperative exclusion criterion, bariatric surgery may increase the risk of alcohol abuse, the study team points out. If this occurred in the study, the results may actually underestimate the beneficial effect of bariatric surgery.

The reliance on claims data is the main limitation, said Dr. Michelle Long, an assistant professor in gastroenterology at Boston University School of Medicine and Boston Medical Center who wasn't involved in the study.

"The prevalence of NAFLD, NASH and cirrhosis was low in this study because these conditions can be clinically silent and difficult to diagnosis without invasive testing," Long said by email. "Most patients with NAFLD are completely unaware of any liver problems and, unfortunately, even patients with cirrhosis do not find out they have it until they develop complications, such as liver cancer."

The findings of this study are nonetheless very relevant for patients because it again shows that the most effective therapy for NAFLD is bariatric surgery, and that bariatric surgery effectively prevents the dangerous consequences of NAFLD, said Dr. Beat Müller, deputy director, managing senior attending surgeon and head of minimally invasive and robot-assisted surgery at the University Hospital Heidelberg in Germany.

"This is also very relevant in light of the fact that there is still no approved drug therapy for NAFLD although many drugs are currently in clinical trials," Müller, who wasn't involved in the study, said by email.

"Therefore, in obese patients with a BMI greater than 40, there is no meaningful alternative to bariatric surgery," Müller said.

SOURCE: https://bit.ly/2xmJJQl Annals of Surgery, online March 27, 2020.