Ultrasound liver elastography for the detection of liver fibrosis in patients with psoriasis and reactive arthritis on long-term methotrexate therapy: A cross-sectional study.

Background: Long-term low-dose methotrexate therapy is associated with liver fibrosis. Although liver biopsy is the gold standard for detecting fibrosis, it is an invasive procedure associated with morbidity and mortality risks. Hence noninvasive imaging techniques such as transient elastography (TE) and shear wave elastography (SWE) have been studied to measure liver stiffness.

Aims: To assess the utility of TE and SWE in detecting fibrosis in patients with psoriasis and reactive arthritis on long-term methotrexate therapy.

Methods: A cross-sectional prospective study was undertaken on 54 patients with psoriasis and reactive arthritis who had received ≥1.5 g of methotrexate. Various clinical and biochemical [fibrosis 4 index (FIB4), aspartate-transaminase-to-platelet ratio index (APRI)] parameters were calculated and liver stiffness measurement (LSM) was done with TE and SWE. The degree of steatosis was measured using controlled attenuation parameter (CAP). Liver biopsy was done when indicated and was interpreted by a pathologist blinded to clinical and imaging results.

Results: Fifty four patients with a mean age of 40.3 years and a male-to-female ratio of 5:1 were included. The mean cumulative methotrexate dose was 3.04 g. The median FIB4, APRI, and gamma-glutamyl transpeptidase-to-platelet ratio values were 0.75, 0.23, and 0.15, respectively. The median LSM for TE and SWE was 5.3 and 7.32 kPa, respectively. SWE and TE showed a weak positive correlation (r = 0.26, P = 0.053). The mean CAP was 217 dB/m (area under the receiver operating characteristic = 0.70). In the 19 of 26 cases whose liver biopsies could be assessed, only 4 (21%) showed F1 fibrosis (Ishak staging). The median LSM on SWE was significantly higher in patients with a cumulative methotrexate dose ≥ 4 g when compared with those with a dose <4 g (9.85 vs 7.1, P = 0.02). Other parameters did not correlate with TE and SWE.

Limitations: The small sample size and the low number of cases with significant fibrosis on histopathology were the major limitations of this study.

Conclusion: Histologically detectable LF is uncommon in patients with psoriasis and reactive arthritis on long-term methotrexate therapy. Both TE and SWE are good at detecting the absence of fibrosis in these patients. In our study, SWE and TE values did not correlate with clinical, biochemical, or histopathological parameters.