Admission Systemic Immune-Inflammation Index Is Associated with Cognitive Performance and Handgrip Strength Three Months After First-Ever Acute Ischaemic Stroke: A Prospective Cohort Study.

BACKGROUND/OBJECTIVES: Admission systemic immune-inflammation index (SII) has been associated with post-stroke cognition, but its concurrent relationships with cognitive and physical performance remain less clear. We examined admission SII in relation to three-month Montreal Cognitive Assessment (MoCA) scores and handgrip strength after first-ever acute ischaemic stroke. METHODS: This single-centre prospective cohort enrolled 185 patients; 149 completed both three-month assessments and were analysed. Continuous MoCA was the primary outcome, and handgrip strength the secondary outcome. Associations were examined with hierarchical linear models, HC3 robust standard errors, and restricted cubic splines. RESULTS: SII correlated inversely with MoCA (ρ = -0.668; p < 0.001) and handgrip strength (ρ = -0.481; p < 0.001). After accounting for measured covariates, a twofold increase in SII was associated, on average, across the observed distribution, with a 2.69-point-lower MoCA score (95% CI: -3.52 to -1.86) and 2.20 kgf lower handgrip strength (95% CI: -3.40 to -1.01). Adding ln(SII) to the clinical model increased unadjusted R2 by 0.209. The adjusted SII-MoCA association was monotonic, inverse, and nonlinear (p = 0.002). CONCLUSIONS: Higher admission SII was associated with lower three-month cognitive and physical performance in this selected cohort. External validation is required before clinical use.