A prospective 5-year study on the use of transient elastography to monitor the improvement of non-alcoholic fatty liver disease following bariatric surgery

Liver stiffness measurement (LSM) by transient elastography (TE) is a non-invasive assessment for diagnosing and staging liver fibrosis in non-alcoholic fatty liver disease (NAFLD). Evidence on its role as a longitudinal monitoring tool is lacking. This study aims to evaluate the role of TE in monitoring NAFLD improvement following bariatric surgery. This study prospectively recruited 101 morbidly obese patients undergoing laparoscopic bariatric surgery for intraoperative liver biopsy. Thirty-seven patients of the cohort received perioperative TE. Postoperative anthropometric, biochemical and LSM data were collected annually for 5 years. In 101 patients receiving liver biopsy (mean age 40.0 ± 10.3 years, mean body-mass-index (BMI) 40.0 ± 5.7 kg/m(2)), NASH and liver fibrosis were diagnosed in 42 (41.6%) and 48 (47.5%) patients respectively. There were 29 (28.7%) stage 1, 11 (10.9%) stage 2, 7 (6.9%) stage 3, and 1 (1.0%) stage 4 fibrosis. In 37 patients receiving TE (mean age 38.9 ± 10.8 years, mean BMI 41.1 ± 5.6 kg/m(2)), the percentages of total weight loss were 21.1 ± 7.6% at 1 year, 19.7 ± 8.3% at 3 years, and 17.1 ± 7.0% at 5 years after surgery. The mean LSM reduced significantly from 9.8 ± 4.6 kPa at baseline to 6.9 ± 3.4 kPa at 1 year, 7.3 ± 3.0 kPa at 3 years, and 6.8 ± 2.6 kPa at 5 years (P = 0.002). Using pre-defined LSM cut-offs, the rates of significant fibrosis, advanced fibrosis and cirrhosis being ruled out at 5 years improved from baseline values of 43.7 to 87.5% (P < 0.001), 56.8 to 91.7% (P < 0.001), and 64.9 to 91.7% (P < 0.001), respectively. TE was a useful monitoring tool in demonstrating the improvement of liver fibrosis following bariatric surgery.