Site-specific skeletal muscle mass and functional prognosis in geriatric stroke patients

Evidence is scarce regarding prognostic value of site-specific muscle mass in geriatric stroke survivors. We aim to assess the association between four measures of muscle mass, namely the skeletal muscle mass index of the limbs (SMI), upper limb SMI (USMI), lower limb SMI (LSMI), and trunk muscle mass index (TMI), and the functional prognosis in stroke patients.

This study conducted a retrospective cohort analysis involving post-acute stroke inpatients. Muscle mass data were obtained through bioelectrical impedance analysis and computed by dividing each muscle mass by the square of the height. The study outcomes included the Functional Independence Measure (FIM) motor at discharge and FIM-motor gain. Multiple regression analysis was conducted to assess the association between SMI, USMI, LSMI, and TMI with outcomes, while adjusting for confounding factors.

A total of 701 patients (mean age 72.8 years, 374 males) were analyzed. As a result, LSMI (β = 0.089, P = 0.003) and SMI (β = 0.083, P = 0.008) were significantly associated in the FIM-motor at discharge, with LSMI showing a stronger association. USMI (β = 0.019, P = 0.521) and TMI (β = 0.035, P = 0.231) showed no significant association. LSMI (β = 0.124, P = 0.003) and SMI (β = 0.116, P = 0.008) were significantly associated with FIM-motor gain; however, USMI (β = 0.027, P = 0.521) and TMI (β = 0.049, P = 0.231) showed no significant association with FIM-motor gain.

Differential associations were observed between site-specific muscle mass and functional prognosis in post-stroke patients. Among these, lower limb muscle mass was most strongly associated with activities of daily living (ADL) recovery.