Association Between Bioelectrical Impedance-Derived Phase Angle and Functional Status in Post-Stroke Patients: A Retrospective Analysis

Background and Objectives: Phase angle (PhA) derived from bioelectrical impedance analysis reflects muscle quality and cellular integrity and has been associated with functional outcomes after stroke. However, its relationship with functional status at hospital admission and potential sex-based differences remains unclear. This study investigated the association between PhA and functional status at admission in post-stroke patients undergoing convalescent rehabilitation. Materials and Methods: This retrospective study included 250 post-stroke patients admitted to a convalescent rehabilitation hospital. PhA was measured at admission and classified into high and low groups using sex-specific cutoffs. Functional status was assessed using the Berg Balance Scale (BBS), Functional Ambulation Category (FAC), and the Korean version of the Modified Barthel Index (K-MBI). Sex-stratified logistic regression analyses were conducted to examine associations between functional variables and low PhA. Results: Patients with low PhA showed significantly poorer balance, ambulation, and activities of daily living (ADL) than those with high PhA. In men, low balance (BBS < 41) and low ambulation ability (FAC < 3) were independently associated with low PhA. In women, low ADL performance (K-MBI < 75) was independently associated with low PhA, while balance and ambulation were not. Conclusions: PhA was significantly associated with functional status at admission in post-stroke patients, with distinct sex-specific patterns. PhA may serve as a simple and non-invasive adjunct indicator of functional vulnerability when interpreted with consideration of sex differences.