Improved noninvasive prediction of liver fibrosis by liver stiffness measurement in patients with nonalcoholic fatty liver disease accounting for controlled attenuation parameter values

Background and aims: Liver stiffness measurement (LSM) frequently overestimates the severity of liver fibrosis In Nonalcoholic Fatty Liver Disease (NAFLD). Controlled Attenuation Parameter (CAP) is a new parameter provided by the same machine used for LSM, and associated with both steatosis and BMI, the two factors mostly affecting LSM peformance in NAFLD. We aimed to determine wheter prediction of liver fibrosis by LSM in NAFLD patients is affected by CAP values. Methods: Patients (n=324) were assessed by clinical and histological (Kleiner score) features. LSM and CAP were performed using the M probe. CAP values were grouped by tertiles (lower from 132 to 298, middle from 299 to 338, higher form 339 to 400 dB/m). Results: Among patients with F0-F2 fibrosis, mean LSM values- expressed in kPa- increased according to CAP tertiles (6.8 vs. 8.6 vs. 9.4; p=0.001), and along this line the AUC of LSM for the diagnosis of F3-F4 fibrosis was progressively reduced from lower to middle and further to higher CAP tertiles (0.915, 0.848-0.982; 0.830, 0.753-0.908; 0.806, 0.723-0.890). As a consequence, in subjects with F0-F2 fibrosis, the rates of false-positive LSM results for F3-F4 fibrosis increased according to CAP tertiles (7.2% in lower vs. 16.6% in middle vs. 18.1% in higher). Consistent with this, a decisional flow-chart for prediciting fibrosis was suggested by combining both LSM and CAP values. Conclusions: In patients with NAFLD, CAP values should always be taken into account in order to avoid overestimations of liver fibrosis assessed by TE. This article is protected by copyright. All rights reserved.