Proposal for new diagnostic criteria for low skeletal muscle mass based on computed tomography imaging in Asian adults

• Low muscle mass is an independent predictor of poor survival in various diseases.
• We investigated the psoas muscle mass index (PMI) using computed tomography imaging in 541 healthy adults in Japan.
• PMI was significantly lower in women and in individuals ≥50 y.
• We established the sex-specific cutoff values of PMI to define low muscle mass.
• This new criterion would be applicable for defining sarcopenia in Asia.

ObjectivesLow skeletal muscle, referred to as sarcopenia, has been shown to be an independent predictor of lower overall survival in various kinds of diseases. Several studies have evaluated the low skeletal muscle mass using computed tomography (CT) imaging. However, the cutoff values based on CT imaging remain undetermined in Asian populations.MethodsPreoperative plain CT imaging at the third lumbar vertebrae level was used to measure the psoas muscle mass index (PMI, cm2/m2) in 541 adult donors for living donor liver transplantation (LDLT). We analyzed PMI distribution according to sex or donor age, and determined the sex-specific cutoff values of PMI to define low skeletal muscle mass.ResultsPMI in men was significantly higher than observed in women (8.85 ± 1.61 cm2/m2 versus 5.77 ± 1.21 cm2/m2; P < 0.001). PMI was significantly lower in individuals ≥50 y than in younger donors in both men and women (P < 0.001 and P < 0.001, respectively). On the basis of the younger donor data, we determined the sex-specific cutoff values for the low skeletal muscle mass were 6.36 cm2/m2 for men and 3.92 cm2/m2 for women (mean − 2 SD).ConclusionData from healthy young Asian adults were used to establish new criteria for low skeletal muscle mass that would be applicable for defining sarcopenia in Asian populations.