Low skeletal muscle mass by computerized tomography is associated with increased mortality risk in end-stage kidney disease patients on hemodialysis.

Background And Aims: Skeletal muscle (SM) area, as measured by abdominal CT at the level of the third lumbar vertebra (L3), has been proposed as a proxy of whole body muscle mass. However, population-specific reference values are lacking. In the present study we aimed at: (1) detecting low SM area on abdominal CT images in patients on hemodialysis by applying cut-offs derived from a group of healthy subjects, and (2) estimating the independent risk of all-cause mortality associated with low SM area.

Methods: We retrospectively enrolled 212 adult patients on hemodialysis, undergoing abdominal CT scan (study group), and 87 healthy kidney donors (reference group). We obtained the gender-specific 5th percentile values of the abdominal SM area distribution from both the whole control group and the subgroup of younger (29-60 years) subjects, which we used as reference cut-offs. Then we applied those cut-offs in the study group to identify patients with low SM area. We used survival and Cox regression analysis to evaluate the risk of all-cause mortality associated with low abdominal SM area.

Results: In the fully adjusted Cox regression analysis, the patients with low abdominal SM area had a higher risk of death than the patients with values above the reference cut-off derived in the subgroup of younger controls (adjHR = 1.79 (1.21; 2.67), P = 0.004).

Conclusions: Abdominal CT imaging can be used to detect low abdominal SM area in patients on hemodialysis by applying cut-offs derived from healthy subjects sharing a similar ethnic background. Low SM area as assessed by CT is independently associated with all-cause mortality in ESKD patients on hemodialysis.