Longitudinal assessment of liver stiffness using ARFI technique does not support increased risk of fibrosis in rheumatoid arthritis patients on methotrexate.

Aims: To assess the liver stiffness in patients with rheumatoid arthritis treated with methotrexate monotherapy using non-invasive, ultrasound-based elastography (acoustic radiation force impulse (ARFI) imaging) in a longitudinal approach.

Methods: In total, 23 MTX-naive patients were longitudinally assessed using acoustic radiation force impulse (ARFI) imaging. Baseline assessments were carried out between July 2018 and April 2019, and the follow-up evaluations took place after an average of 2.6 years. The main outcome variable was the mean shear wave velocity as measured by the ARFI method. It was calculated from 10 valid ARFI measurements for each patient. Inferential statistical analyses (within-group comparisons) were performed using t-tests for dependent samples or suitable nonparametric procedures.

Results: The main finding was that observed ARFI shear wave velocities did not increase during the observation period. In fact, this parameter decreased over time from 1.07 m/s (SD = 0.23) at baseline without MTX exposure to 0.97 m/s (SD = 0.16) at follow-up after a mean of 2.6 years (P = 0.013). Moreover, the magnitude of the change in shear wave velocity could not be predicted by indicators of inflammation or disease activity, BMI, age, sex or NSAR intake (corresponding regression analysis: corrected R = 0.344; P = 0.296).

Conclusions: No increased risk of liver fibrosis was found in RA patients treated with MTX monotherapy during observation period.