Non-obese patients with nonalcoholic fatty liver disease may use a lower liver stiffness cut-off to assess fibrosis stages

Objective We aimed to estimate the optimal cut-off values of liver stiffness measurement (LSM) for diagnosing and staging fibrosis in non-obese and obese patients with nonalcoholic fatty liver disease (NAFLD). Methods NAFLD patients diagnosed by liver biopsy according to the Nonalcoholic Steatohepatitis Clinical Research Network scoring system were enrolled in this study. Non-obesity was defined as a body mass index (BMI) less than 25 kg/m2 . LSM was performed by experienced physicians within 2 weeks before or after liver biopsy. Results A total of 158 patients were included. Average BMI of the non-obese (n = 68) and obese (n = 90) groups was 23.2 ± 1.6 and 27.9 ± 2.5 kg/m2 , respectively. After adjusted for age, fibrosis stage, steatosis grade and type 2 diabetes mellitus, the obese group had a LSM of 3.522 kPa higher than the non-obese patients (P = 0.003). LSM values of the non-obese patients had a lower trend when stratified by fibrosis stage, especially in cirrhosis (F4; P = 0.021). Applying separate cut-off values for patients with NAFLD in individual fibrosis stage, 5.8 vs 7.5 kPa (≥ F1), 7.6 vs 8.5 kPa (≥ F2), 9.1 vs 11.2 kPa (≥ F3), and 12.5 vs 14.3 kPa (F4), improved their diagnostic odds ratios compared with overall cut-off values. In the non-obese NAFLD group, using a separate cut-off avoided underestimating 9.1% of patients with cirrhosis. Conclusions Non-obese NAFLD group had lower LSM than the obese group. Different cut-off values should be used to measure liver fibrosis stage in non-obese and obese NAFLD patients.