Associations between novel myosteatosis indices measured by computed tomography and muscle strength in patients undergoing hemodialysis.

BACKGROUND: Novel myosteatosis indices that measure intra- and inter-muscular fat content in abdominal muscles using computed tomography (CT) have been recently introduced. Therefore, we evaluated their usefulness in diagnosing low muscle strength in patients undergoing hemodialysis. METHODS: This study included 114 patients on maintenance hemodialysis who underwent CT and handgrip strength assessments. Skeletal muscle density , total abdominal muscle area, normal-attenuation muscle area , low-attenuation muscle area, and intermuscular adipose tissue area at the third lumbar vertebral level were measured. Additionally, novel myosteatosis indices (normal-attenuation muscle area/total abdominal muscle area, low-attenuation muscle area/height2, and intermuscular adipose tissue area/total abdominal muscle area) were calculated. The relationship between myosteatosis indices and handgrip strength was examined. RESULTS: Skeletal muscle density, normal-attenuation muscle area/total abdominal muscle area index, low-attenuation muscle area/height2, and intermuscular adipose tissue area/total abdominal muscle area index were 34.4 ± 9.0 Hounsfield Unit (HU), 58.2 ± 17.0%, 14.3 ± 5.7 cm2/m2, and 7.2 (3.9-12.8)%, respectively. The normal-attenuation muscle area/total abdominal muscle area index (r = 0.987), low-attenuation muscle area/height2 (r = 0.853), and log-transformed intermuscular adipose tissue area/total abdominal muscle area index (r = 0.843) were significantly correlated with skeletal muscle density (all P < .0001). Additionally, skeletal muscle density (β = 0.305), normal-attenuation muscle area/total abdominal muscle area index (β = 0.297), low-attenuation muscle area/height2 (β = -310), and intermuscular adipose tissue area/total abdominal muscle area index (β = -0.321) were independently linked to handgrip strength. The diagnostic value of the new myosteatosis index was similar to that of skeletal muscle density: age-sex-adjusted C-statistics (0.810): normal-attenuation muscle area/total abdominal muscle area index (0.809, P = .84), low-attenuation muscle area/height2 (0.810, P = .98), and intermuscular adipose tissue area/total abdominal muscle area index (0.810, P = .97). Increase in normal-attenuation muscle area/total abdominal muscle area index, but not in skeletal muscle density, was independently associated with reduced risk of low handgrip strength. Increase in intermuscular adipose tissue area/total abdominal muscle area index, but not low-attenuation muscle area/height2, was independently associated with greater risk of low handgrip strength. CONCLUSIONS: Novel myosteatosis indices were independently associated with handgrip strength in patients undergoing hemodialysis and demonstrated diagnostic usefulness, were clinically acceptable, and comparable to that of skeletal muscle density.