A Comparison of Muscle Function, Mass, and Quality in Liver Transplant Candidates: Results From the Functional Assessment in Liver Transplantation Study

Abstract

Background: Sarcopenia and functional impairment are common and lethal extrahepatic manifestations of cirrhosis. We aimed to determine the association between computed tomography (CT)-based measures of muscle mass and quality (sarcopenia) and performance-based measures of muscle function.

Methods: Adults listed for liver transplant underwent testing of muscle function (grip strength, Short Physical Performance Battery [SPPB]) within 3 months of abdominal CT. Muscle mass (cm/m) = total cross-sectional area of psoas, paraspinal, and abdominal wall muscles at L3 on CT, normalized for height. Muscle quality = mean Hounsfield units for total skeletal muscle area at L3.

Results: Among 292 candidates, median grip strength was 31 kg, SPPB score was 11, muscle mass was 49 cm/m, and muscle quality was 35 Hounsfield units. Grip strength weakly correlated with muscle mass (ρ = 0.26, P < 0.001) and quality (ρ = 0.27, P < 0.001) in men, and muscle quality (ρ = 0.23, P = 0.02), but not muscle mass, in women. Short Physical Performance Battery correlated weakly with muscle quality in men (ρ = 0.38, P < 0.001) and women (ρ = 0.25, P = 0.02), however, did not correlate with muscle mass in men or women. After adjustment for sex, model for end-stage liver disease (MELD)-Na, hepatocellular carcinoma, and body mass index, grip strength (hazard ratio [HR], 0.74; 95% confidence interval [95% CI], 0.59-0.92; P = 0.008), SPPB (HR, 0.89; 95% CI, 0.82-0.97; P = 0.01), and muscle quality (HR, 0.77; 95% CI, 0.63-0.95; P = 0.02) were associated with waitlist mortality, but muscle mass was not (HR, 0.91; 95% CI, 0.75-1.11; P = 0.35).

Conclusions: Performance-based tests of muscle function are only modestly associated with CT-based muscle measures. Given that they predict waitlist mortality and can be conducted quickly and economically, tests of muscle function may have greater clinical utility than CT-based measures of sarcopenia.

Figure 1

Scatter plots depicting gender-specific correlations between grip strength with skeletal muscle index (A), muscle attenuation (B), and the Short Physical Performance Battery with skeletal muscle index (C), muscle attenuation (D).