Transient elastography reliably estimates liver fibrosis in autoimmune hepatitis

Aim of the study
Autoimmune hepatitis (AIH) may result in liver fibrosis and cirrhosis. While the gold standard for staging fibrosis is biopsy, transient elastography (TE) represents a non-invasive alternative. TE has been validated in several chronic liver diseases, but no data exist to establish an association between histologic fibrosis on biopsy and TE liver stiffness measurements among a United States cohort of AIH patients.

Material and methods
We conducted a retrospective cohort study of 53 AIH patients who received TE assessment and liver biopsy. Histologic fibrosis was classified as advanced (F3-F4) or mild/moderate (F0-F2). Liver stiffness by TE was measured in kilopascals (kPa). We performed a score test for trend to test the association between histologic fibrosis stage and increasing TE kPa categories. Analyses incorporated probe type (medium or extra-large) and body mass index (BMI). Linear regression was used to generate predicted associations between median kPa and histologic fibrosis score with the medium probe.

Results
The cohort was primarily female (83%) with median age 56.3 years. Increasing kPa category was associated with worsening fibrosis stage when using the medium probe (p = 0.04), but not the extra-large probe (p = 0.40). BMI, however, differed between these groups (median 25.8 vs. 33.1, respectively, p < 0.001). In adjusted linear regression, increasing median kPa corresponded well to worsening fibrosis stage (p = 0.003).

Conclusions
In a United States AIH cohort, increasing TE kPa measurements are associated with worsening histologic fibrosis staging. While medium probe performance was superior to the extra-large probe, significant variation in BMI between groups may explain this difference.