Five‐Year CT ‐Based Skeletal Muscle Decline Curves in Cirrhosis According to Liver Functional Reserve and Routinely Available Clinical Factors

ABSTRACT Background Sarcopenia is common in cirrhosis and is associated with poor outcomes. We aimed to identify factors associated with longitudinal skeletal muscle loss and to explore estimation of future L3 skeletal muscle index (L3‐SMI) using routinely available clinical variables. Methods This retrospective longitudinal study included 175 patients with cirrhosis who underwent serial abdominal CT over five annual time points between 2010 and 2022. The primary analysis used a linear mixed‐effects model including annual time point, baseline Child–Pugh class, and their interaction. An exploratory linear regression model estimated Year 5 L3‐SMI. Results In the primary model, L3‐SMI declined by −1.144 cm 2 /m 2 /year in baseline Child–Pugh class A. The time‐by‐class B interaction was not significant ( β = 0.024; 95% CI, −0.250 to 0.298; p = 0.865), whereas class C was associated with an additional annual decline of −1.812 cm 2 /m 2 /year compared with class A (95% CI, −2.735 to −0.890; p = 0.0001). This association remained after adjustment for age, sex, baseline HCC status, and the time‐by‐HCC interaction. In the exploratory Year 5 model, baseline L3‐SMI was the dominant predictor; estimates for class C were interpreted cautiously because only five patients were baseline class C. Conclusions Baseline hepatic functional reserve, particularly Child–Pugh class C, was associated with faster annual CT‐based L3‐SMI decline. The Year 5 prediction model is exploratory and requires external validation. Early sarcopenia assessment may facilitate risk stratification in patients with impaired hepatic reserve. Trial Registration: UMIN Clinical Trials Registry: UMIN000051577.