Differential Effects of Stroke Stage and Age on Sarcopenia in Stroke Patients: A Cross-Sectional Study

Sarcopenia is highly prevalent among stroke patients and is associated with poor functional outcomes; however, differences across stroke stages and age groups remain unclear. This cross-sectional study enrolled 80 stroke patients from a regional teaching hospital in Taiwan, categorized into chronic (n = 40) and post-acute care (PAC) groups (n = 40), and further stratified into younger (40–64 years, n = 44) and older (≥65 years, n = 36) groups. Assessments included body composition, muscle strength, ultrasound-measured muscle thickness, gait speed, calf circumference, sarcopenia screening (SARC-F), nutritional status, and health-related quality of life. No significant differences were observed in muscle mass, muscle strength, or ultrasound-derived muscle thickness between the chronic and PAC groups. However, the PAC group demonstrated poorer functional outcomes and health-related quality of life, including lower gait speed (p = 0.018), and lower EQ-5D index and visual analogue scale scores (p = 0.006 and p = 0.002, respectively). In contrast, the chronic group showed a higher prevalence of sarcopenia (p < 0.001), a higher mean SARC-F scores (p = 0.004), a greater proportion of low appendicular skeletal muscle mass index (ASMMI, p = 0.025), and reduced calf circumference (p < 0.001). Age-stratified analysis revealed that older patients had lower muscle mass and structural parameters, including ASMMI (p < 0.001), fat-free mass (p < 0.001), quadriceps thickness (p < 0.001), and calf circumference (p = 0.002), along with a higher prevalence of sarcopenia (p < 0.001). These findings indicate that stroke stage is more closely associated with functional impairment, whereas aging predominantly affects muscle mass and sarcopenia severity.