Complete resolution of nonalcoholic fatty liver disease (NAFLD) is highly likely to occur following sustained weight loss in obese patients who have undergone bariatric surgery, although there are still some who may develop new or worsened features of NAFLD, a study has shown.

Researchers performed a systematic review and meta-analysis of studies evaluating liver biopsy results before vs after bariatric surgery in obese patients. Primary endpoints included biopsy-confirmed resolution of NAFLD and NAFLD activity score (NAS). Secondary outcomes were worsening of NAFLD after surgery and liver volume.

Pooled data from 32 cohort studies involving 3,093 biopsies revealed that bariatric surgery led to a biopsy-confirmed resolution of steatosis in 66 percent of patients (95 percent CI, 56–75), inflammation in 50 percent (35–64), ballooning degeneration in 76 percent (64–86) and fibrosis in 40 percent (29–51).

Furthermore, mean NAS substantially dropped after bariatric surgery (mean difference, 2.39; 1.58–3.20; p<0.001).

Interestingly, bariatric surgery resulted in new or worsening NAFLD features, such as fibrosis, in 12 percent (5–20) of patients.

Overall quality of evidence, evaluated using the GRADE approach, was very low.

Although the present data yielded positive results, researchers emphasized the need to further investigate the therapeutic benefits of bariatric surgery for patients with NAFLD.

In a previous study investigating potential predictors of resolution of NAFLD after bariatric surgery, weight loss was associated with decreased alanine aminotransferase (ALT) levels by 6 months postsurgery. Other factors independently associated with ALT decline were improved fasting glycaemia, insulin resistance and dyslipidaemia indices. ALT was used as a surrogate marker of NAFLD. [Diabetes 2018;doi:10.2337/db18-341-OR]