Muscle fat infiltration in obese patients is associated with NAFLD related fibrosis severity - results from a prospective imaging study

Lanthier, Nicolas [UCL] Hiel, Sophie [UCL] Nachit, Maxime Younes [UCL] Rodriguez, Julie [UCL] Thissen, Jean-Paul [UCL] Trefois, Pierre [UCL] Delzenne, Nathalie M. [UCL]

Background and aims: The association between NAFLD and visceral adipose tissue or sarcopenia has been reported, although results are discordant. The goal of this study is to analyze the spectrum of NAFLD among obese patients recruited prospectively and to detect clinical, biological and imaging data associated with steatosis or fibrosis. Methods: Baseline data of obese patients (BMI ≥ 30) randomized in a single center (Food4Gut study) were recorded. Transient elastography (TE) was done to quantify both liver steatosis by controlled attenuation parameter (CAP) measurement and liver fibrosis by liver stiffness measurement (LSM). Body composition was evaluated using bioelectrical impedance analysis. Subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), muscle areas and muscle fat infiltration (MFI) were measured on CT-scan images at the third lumbar level. Results Fifty-two Caucasian patients (mean age: 50 years, 50 % male, mean BMI 35.8) were included. TE was successful in 49 patients (94%). XL probe was used in 20 patients (38%). Mean LSM was low (6.5 kPa). Mean CAP result was high (324 dB/m) with the majority of the patients (73%) presenting severe steatosis (CAP ≥ 296 dB/m). 12 patients (24%) had advanced fibrosis defined by LSM ≥ 7.8 kPa (M probe) or ≥ 6.4 kPa (XL probe). Factors associated with severe steatosis and advanced fibrosis are summarized in the table. Interestingly, severe steatosis was associated with higher muscle quantity and severe fibrosis with a lower muscle density index, compatible with MFI. In a multivariate logistic regression analysis, MFI was the strongest predictor of advanced liver fibrosis. Conclusion In summary, among obese patients, a high proportion of severe steatosis was diagnosed and advanced liver fibrosis was suspected in 24% of the patients. MFI provides a robust, skeletal muscle-specific characteristic linked to advanced fibrosis in NAFLD, suggesting a muscle-liver axis in the pathogenesis of NAFLD complications.