Introduction
Sarcopenia defined as having low muscle mass, muscle strength and if combined with low performance indicate severe sarcopenia1. It is associated with adverse outcomes in cirrhosis, including hepatic encephalopathy, ascites, infection, and increased hospitalisation. Sarcopenia is measured using cross-sectional CT scanning. Thigh ultrasound (TUS) may be a low-cost tool to identify sarcopenia in cirrhosis.
Aims & Methods
We aim to validate TUS for measurement of total-muscle-thickness (TMT) and superficial fat thickness (SF) in cirrhosis using bioelectrical impedance analysis (BIA) as a standard. Cirrhotic patients were recruited from a tertiary-hepatology-clinic for this prospective cross-sectional study. Using TUS at right thigh, average readings on B-mode at one-half of the total distance from the top-of-the-patella to the iliac crest were recorded. BIA was performed as the validation standard (SECA mBCA 525) using Sergi-sarcopenia-equation2. Validated functional muscle metrics (gait speed, handgrip, and sit-to-stand) and liver-frailty-index (LFI)3 were recorded. Statistical analysis was performed using Stata version 17.0.
Results
Total of 124 individuals were recruited. 80 patients {56% (n=45) alcohol-liver-disease, 19% (n=15) non-alcoholic steatohepatitis, 5% (n=4) viral, 4% (n=3) autoimmune, 12% (n=10) combination of above and 4% (n=3) other aetiologies} were included. 44 healthy controls (HC) were included. Most patients were male (n=45, 56%), with mean age 59 years old (SD=10), mean Child-Pugh score 6 (IQR=5-7) and MELD 11 (IQR=7-12). 14 patients (18%) had clinical ascites and 27% (n=19) were actively drinking alcohol. Of cirrhotic, 15 (33%) male and 2 (6%) female were sarcopenic.
Using TUS, TMT was lower in cirrhotic cohort vs HC (female: 17.9 vs 29 mm and male: 32 vs 43.7 mm, SD 7 and 9 respectively, p < 0.001). BIA height adjusted appendiceal muscle mass (ASMI) correlates strongly with TMT (r=0.46, P <0.001). BIA height-adjusted skeletal muscle mass (SMI) also strongly correlated with TUS-measured TMT (male r=0.71 and female r=0.43, P<0.001). it was found that TMT significantly predicted SMI both in male and female patient ( β= 0.39 vs 0.2 with P <0.001 and P=0.02 respectively).
TMT ≥ 3.66 cm in men would exclude sarcopenia (sensitivity=71%, specificity=82%) with likelihood ratio of 3.92 and AUROC 0.85. Intra-rater and Inter-rater reliability for TMT was good (p<0.001). SF measured through TUS strongly correlated with height-adjusted fat mass via BIA (r = 0.58, P< 0.001).
Using functional testing, HCs were walking faster (3.11 vs 4.25 secs, p <0.001). Sit-to-stand time was lower in HCs (8.94 vs 13.4 secs, p =0.001) and hand-grip strength higher in HC (p< 0.001). 13% (n=6) of male and 26% (n=9) of female were frail and frailty scores negatively correlated with TMT (r=-0.3, p=0.005).
Conclusion
TUS is a rapid, valid point-of-care test which can identify high-risk patients with systemic sarcopenia in cirrhosis. Furthermore, lower TMT is associated with increased frailty and reduced muscle function in cirrhosis. Further prospective studies are required to determine if this can be used with other biomarkers to identify patients who would benefit from intensive nutrition intervention.
References
1. Alfonso J Cruz-Jentoft et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing 2019 Jan 1;48(1):16-31
2. Giuseppe Sergi et al. Assessing appendicular skeletal muscle mass with bioelectrical impedance analysis in free-living Caucasian older adults. Clin Nutr. 2015 Aug; 34(4):667-73
3.Jennifer C Lai et al. Development of a novel frailty index to predict mortality in patients with end-stage liver disease Hepatology 2017 Aug;66(2): 564-574
