Temporal muscle thickness is associated with clinical frailty in patients with severe acute brain injury.

Background/Objective: Frailty predicts adverse outcomes in critically ill patients. Characterizing and measuring frailty in the intensive care unit is challenging since most frailty scales are created for the outpatient population. Temporalis muscle thickness (TMT), measured on head imaging, decreases in patients with sarcopenia and may offer an objective index of frailty among patients with SABI. The objective of this study was to test the relationship between TMT and the Clinical Frailty Scale (CFS) in this population. Methods: In this prospective, single-center, observational cohort study, we enrolled subjects with SABI who had routine head computed tomography within 48 h of hospital admission. We calculated Spearman and Pearson correlation coefficients between CFS, TMT, and age. We also tested the relationship between CFS and TMT using multivariable ordinal regression. Finally, we compared the values of TMT and CFS in this cohort with those observed in a post-cardiac arrest cohort. Results: In 51 enrolled patients, TMT was negatively correlated with CFS (ρ = -0.32, p = 0.02) and age (r = -0.45, p = 0.001), while CFS was positively correlated with age (ρ = 0.31, p = 0.03). The relationship between TMT and CFS remained significant when adjusted for albumin level and body mass index (OR 0.63, 95%CI 0.40-0.98). Median TMT and CFS values did not differ between the SABI and post-arrest cohorts, though the shapes of their distributions did. Conclusions: TMT demonstrated a moderate correlation with pre-morbid CFS in patients with SABI, suggesting it might aid in characterizing frailty in this population.