Background: Sarcopenia, or severe loss of muscle mass, is common in cirrhotics and adversely affects quality of life and transplant outcomes. Obese liver transplant(LT) candidates are a subgroup in whom the diagnosis of sarcopenia remains poorly characterized. We compared computed tomography(CT)-based measures of muscle mass and quality with performance-based measures of physical function in obese vs. non-obese LT candidates.

Methods: Included were adults listed for LT with an abdominal CT within 3 months of physical function tests using grip strength and the Short Physical Performance Battery(SPPB=chair stands, gait speed, and balance). Muscle mass=total abdominal skeletal muscle area at L3 / height²(cm²/m²). Muscle quality=mean Hounsfield units(HU) for total skeletal muscle area at L3. Sarcopenia was defined by sex- and BMI-specific cutoffs of muscle mass. Linear regression, adjusted for MELDNa and sex, assessed the relationship between muscle function and mass.

Results: Of 292 patients(pts), 96(33%) were obese(BMI≥30kg/m²). Obese vs. non-obese pts were more likely to have NASH (16 vs. 4%; p<0.01), but were similar by %female (29 vs. 36%), %ascites (29 vs. 33%), median age (61 vs. 61) and MELDNa (18 vs. 17) [p>0.05 for each]. Median muscle mass was higher (53 vs. 47cm²/m²; p<0.01) in obese vs. non-obese pts, but median muscle quality was lower (33 vs. 37HU; p<0.01). While obese (vs. non-obese) pts had lower rates of sarcopenia (30 vs. 42%; p=0.045), they were more impaired by chair stands time (p=0.02), grip strength (p=0.04), and composite SPPB (p=0.03). Gait speed and balance were similar between these groups. The relationship between muscle mass and SPPB varies by BMI (interaction p=0.02) but not grip strength (p=0.69). In non-obese pts, muscle mass was strongly associated with both grip strength (coef=0.31; p<0.01) and SPPB (coef=0.06; p=0.01), even after adjustment for MELDNa and sex. However, in obese pts, muscle mass was associated with neither grip strength (coef=0.16; p=0.10) nor SPPB (coef=0.01; p=0.77).

Conclusion: Obese, compared to non-obese, LT candidates have lower rates of sarcopenia by CT-based measures, but are more impaired by performance-based measures of physical function. Physical function is correlated with muscle mass in non-obese but not in obese LT candidates. Further investigation to better define sarcopenia in obese LT candidates using objective metrics incorporating physical function rather than simply quantifying muscle mass is warranted.

CITATION INFORMATION: Wang C, Lobach I, Lai J. Muscle Function, Mass, and Quality in Obese Liver Transplant Candidates: Results from the Functional Assessment in Liver Transplantation (FrAILT) Study. Am J Transplant. 2016;16 (suppl 3).

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