Differences among Three Skeletal Muscle Mass Indices in Predicting Non-Alcoholic Fatty Liver Disease: Korean Nationwide Population-Based Study

Muscle Fat Content Is Associated with Nonalcoholic Fatty Liver Disease and Liver Fibrosis in Chinese Adults

OBJECTIVES

Several studies have linked myosteatosis with nonalcoholic fatty liver disease (NAFLD) in individuals with obesity. The clinical significance of myosteatosis in individuals with NAFLD in the general population has not been well investigated. Here, we wanted to explore and compare the associations of NAFLD and liver fibrosis with muscle fat content and skeletal muscle mass (SMM) in a relatively large general population in China.

METHODS

We retrospectively included all participants who underwent abdominal CT scans in our health promotion center between April 2021 and October 2021. Muscle fat content was assessed by abdomen quantitative computed tomography (QCT) scans, and SMM was evaluated by bioelectrical impedance. NAFLD was assessed by ultrasonography. The NAFLD fibrosis score (NFS) and Fibrosis-4 Index (FIB-4) score were calculated to assess liver fibrosis.

RESULTS

Compared with participants without NAFLD, patients with NAFLD showed significantly increased intermuscular adipose tissue (IMAT%) (7.40±3.37% vs. 6.76±2.66%, P <0.01). According to a multiple logistic regression model, IMAT% (OR=1.091, 95% CI 1.030-1.155, P=0.003) was only independently correlated with NAFLD in obese participants. Mediation analysis showed that BMI mediated the association between IMAT% and NAFLD. In participants with NAFLD, increased IMAT% was independently associated with an increased intermediate to high risk of advanced fibrosis assessed by the NFS or FIB-4 score after adjusting for multiple potential confounders. However, SMM was only independently correlated with an intermediate to high risk for advanced fibrosis evaluated by the NFS and not by the FIB-4 score.

CONCLUSION

Increased muscle fat content is positively correlated with NAFLD and intermediate to high risk for advanced fibrosis in the general Chinese population.

Cutoff Points of Waist Circumference for Predicting Incident Non-Alcoholic Fatty Liver Disease in Middle-Aged and Older Korean Adults

This study aimed to determine the optimal cutoff value of waist circumference (WC) for predicting incident NAFLD. In this community-based prospective cohort study, we analyzed data from 5400 participants without NAFLD at baseline aged 40−69 years. NAFLD was defined as a NAFLD-liver fat score >−0.640. A Cox proportional hazards regression model was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for an association between body composition and NAFLD incidence. The predictive power of each body composition indicator was assessed by Harrell’s concordance index for Cox models. During a mean follow-up period of 12 years, there were 2366 new-onset NAFLD events. Compared with men with WC < 81 cm, the adjusted HR (95% CI) for incident NAFLD in those with WC ≥ 81 cm was 2.44 (2.23−2.67). Compared with women with WC < 78.5 cm, the adjusted HR (95% CI) for incident NAFLD in those with WC ≥ 78.5 cm was 2.54 (2.25−2.87). WC was the most significant risk factor for predicting incident NAFLD among body composition indicators in middle-aged and older Korean adults. The optimal WC cutoff point for predicting incident NALFD was 81 cm in men and 78.5 cm in women, which might assist in the early detection and prevention of NAFLD.

Ultrasound Measurements of Rectus Femoris and Locomotor Outcomes in Patients with Spinal Cord Injury

Patients with incomplete spinal cord injury have decreased mobility, and many do not recover walking ability. The purpose of this study was to investigate rectus femoris muscle thickness and echo intensity on ultrasound and functional outcomes in these patients. This was a prospective cohort study in an inpatient rehabilitation center, which recruited 40 consecutive patients with incomplete spinal cord injury. The patients underwent an ultrasound assessment at 6 weeks post-injury. Ultrasound measurements were performed using B-mode ultrasound scanning and standardized protocols. Functional outcomes on discharge, including Lower Extremity Muscle Score (LEMS), Functional Independence Measure (FIM), and Walking Index for Spinal Cord Injury II (WISCI II), were measured. Rectus femoris muscle thickness was significantly correlated with discharge LEMS (Spearman’s rho = 0.448; p = 0.004), FIM motor subscale (Spearman’s rho = 0.595; p < 0.001), FIM walk subscale (Spearman’s rho = 0.621; p < 0.001) and WISCI II (Spearman’s rho = 0.531; p < 0.001). The rectus femoris echo intensity was also significantly correlated with discharge LEMS (Spearman’s rho = −0.345; p = 0.029), FIM motor subscale (Spearman’s rho = −0.413; p = 0.008), FIM walk subscale (Spearman’s rho = −0.352; p = 0.026), and WISCI II (Spearman’s rho = −0.355; p = 0.025). We report that a relationship exists between rectus femoris muscle ultrasonographic characteristics and muscle function and ambulatory outcomes after inpatient rehabilitation. Ultrasound muscle measurements are potentially useful in assessing muscle wasting and function in patients with spinal cord injury.