Analysis of the optimal psoas muscle mass index cut-off values, as measured by computed tomography, for the diagnosis of loss of skeletal muscle mass in Japanese people

This study aimed to determine the optimal psoas muscle mass index (PMI) cut-off values for diagnosis of skeletal muscle mass loss.

Methods: We evaluated PMI in two groups of normal controls: a medical check-up group and a liver donation candidate group. We analyzed two novel PMI cut-off values, one based on the mean - two standard deviations (2SD) and one based on the lower 5%. Skeletal muscle mass index (SMI) evaluations using computed tomography (sliceOmatic; TomoVision) and bioelectrical impedance analysis and PMI evaluation were undertaken simultaneously. We analyzed the correlation between our PMI cut-off values and the Japan Society of Hepatology-defined SMI cut-off values. The prevalence of skeletal muscle mass loss in patients with liver disease was assessed using the novel PMI cut-off values.

Results: In 504 normal controls aged ≤50 years, the PMI cut-off values based on mean -2SD and the lower 5% were set at 3.30 cm² /m² for men and 1.69 cm² /m² for women and 3.74 cm² /m² for men and 2.29 cm² /m² for women, respectively. The PMI cut-off values based on the lower 5% alone showed that skeletal muscle mass loss increased with age. Furthermore, they correlated well with Japan Society of Hepatology-defined SMI (sliceOmatic) cut-off values and showed a significantly higher prevalence of skeletal muscle mass loss in patients with liver cirrhosis than those without liver cirrhosis.

Conclusions: We propose the following PMI cut-off values: 3.74 cm² /m² for male individuals and 2.29 cm² /m² for female individuals. These cut-off values can facilitate accurate diagnosis and management of sarcopenia in patients with chronic liver disease.