Utility of bioelectrical impedance vector analysis for assessing body composition and its association with ambulatory recovery after hip fracture

Abstract

Background: Functional recovery after hip fracture is often complicated by interrelated geriatric syndromes such as malnutrition, sarcopenia, and cognitive impairment, which alter body composition and worsen outcomes. Bioelectrical impedance vector analysis (BIVA) is a promising tool for evaluating body composition; however, its clinical relevance in post-fracture rehabilitation remains insufficiently explored. This study examined whether BIVA is associated with these conditions and functional recovery.

Methods: In this prospective observational study, 99 adults aged ≥65 years who underwent hip fracture surgery and initiated inpatient rehabilitation were evaluated. Ambulation was assessed over 12 months. Bioelectrical impedance vectors were compared among groups stratified by nutritional, sarcopenic, cognitive, and functional status. Functional recovery trajectories were plotted on reference tolerance ellipses, and prognostic value was analyzed.

Results: BIVA demonstrated significant vector shifts across nutritional, sarcopenic, cognitive, and functional categories, with poorer status associated with rightward or downward displacement. Poor ambulators frequently showed vectors outside the 95% tolerance ellipse at baseline, and these patients had lower cumulative recovery of independent ambulation. In multivariable Cox analysis, vectors outside the 95% tolerance ellipse were associated with lower likelihood of recovery at 3 months (hazard ratio [HR] 0.458; 95% confidence interval [CI] 0.262-0.800; p = 0.006), 6 months (HR 0.525; 95% CI 0.302-0.914; p = 0.023) and 12 months (HR 0.510, 95% CI: 0.297-0.877, p = 0.015).

Conclusions: BIVA is a feasible and informative tool for identifying body composition impairment in older adults undergoing rehabilitation after hip fracture. BIVA measurements were associated with functional recovery differences and may provide complementary information for risk stratification during pre-rehabilitation assessment.