We read with interest the study by Brietzke et al. titled “Predictors of Skeletal Muscle Index for Patients Treated With Hemodialysis,” published in the journal.1 The study is a secondary analysis of cross-sectional data from a database of 178 hemodialysis patients aiming to evaluate predictors of skeletal muscle mass (SMM) index in hemodialysis patients. Among several selected candidate variables, the authors found that urea reduction ratio (URR) was the only variable significantly associated with the SMM index in both univariate and multiple linear regression models.