Probability-based interpretation of liver stiffness measurement in untreated chronic hepatitis B patients

Liver stiffness measurement (LSM) by transient elastography is a popular noninvasive test of fibrosis. Traditional LSM cutoffs dichotomize patients and do not clearly indicate the confidence of diagnosis.

We derived and validated probability functions of fibrosis and cirrhosis based on LSM and determined the effect of alanine aminotransferase (ALT) on the scores.

Consecutive chronic hepatitis B patients who underwent liver function tests, LSM, and liver biopsies at six European and Asian centers (2/3 in the training cohort and 1/3 in the validation cohort) were recruited. Binary logistic regression was performed to predict the probabilities of different fibrosis stages based on LSM and/or ALT.

A total of 1,051 patients were included in the final analysis (53 % with ALT ≥ 60 IU/L, 32 % F2, 20 % F3, and 24 % F4). The probability functions (LiFA-HBV score) with and without ALT adjustment closely mirrored the proportion with different fibrosis stages in both the training and validation cohorts. For a range of up to 300 IU/L, ALT maintained a weak linear relationship with LSM for each fibrosis stage (r (2) = 0.018-0.13). Based on relative integrated discrimination improvement, the addition of ALT to the LiFA-HBV score increased the correct reclassification of F3-4 and F4 by 5 and 17 %, respectively.

ALT increases LSM in a linear fashion in chronic hepatitis B patients at any fibrosis stage. The LiFA-HBV score accurately predicts the probability of fibrosis. ALT adjustment increases the rate of reclassification modestly and is not essential.