Reliability of liver stiffness measurement in non-alcoholic fatty liver disease: the effects of body mass index

Abstract

International audienceBackground: Liver stiffness measurement (LSM) by transient elastography (TE) is used to stage fibrosis in patients with liver disease, but its diagnostic reliability and the factors affecting its performance in patients with non-alcoholic fatty liver disease (NAFLD) are incompletely understood. Methods: Consecutive NAFLD patients (n=169), assessed by liver biopsy (Kleiner score), anthropometric, biochemical and metabolic features, underwent LSM by TE with standard M probe. Results: LSM was not reliable in 23 patients (13.6%), due to obesity. Among patients with a reliable TE, a LSM value >7.25 KPa was the best cut-off for predicting significant fibrosis at biopsy (AUC 0.794), yet this cut-off still failed to rule out F2-F4 fibrosis in 30.8% (false-negative rate) or rule in F3-F4 in 29.4% (false-positive rate). Similarly a LSM value >8.75 KPa was the best cut-off for severe fibrosis (F3-F4) (AUC 0.870), with a rate of false-negatives of 24.2% and of false-positives of 2.1%. Body mass index was the major determinant of these diagnostic errors in predicting significant and severe fibrosis both by overestimating or underestimating the stage of fibrosis. Conclusions: In NAFLD patients, even when LSM is feasible, high BMI values affect negatively the diagnostic reliability. Improved performance of TE could be obtained using specifically designed probes