The implications of bioelectrical impedance vector analysis in older adults with hip fractures

Objectives

This study used bioelectrical impedance vector analysis to assess body composition in older adults with hip fractures, comparing results with reference populations.

Study design

This cross-sectional study included patients aged 65 years or more who had undergone surgery for hip fracture and baseline bioelectrical impedance analysis at 50 kHz. Using raw impedance data, bioelectrical impedance vector analysis was conducted, calculating phase angle and analyzing resistance (R) and reactance (Xc) relative to height (R/H and Xc/H) on RXc graphs.

Main outcome measures

Men and women were compared with reference populations using confidence ellipses. Individual vectors were plotted against 50 %, 75 %, and 95 % tolerance ellipses and compared with international references matched for age and body mass index and a young adult group, further differentiated by sarcopenia status.

Results

Among 103 patients with hip fracture (24 men, 79 women), confidence ellipses showed significant differences from reference populations (P < 0.001), with reduced Xc and lower phase angle (men: 4.3 ± 1.5°; women: 3.8 ± 1.0°), consistent with higher R/H and lower Xc/H. Most vectors lay outside the 75 % and 95 % tolerance ellipses, primarily in the lower-right and upper-right quadrants, indicating body cell mass loss and water imbalance. Only 8.3 % of men and 12.7 % of women fell within the 75 % tolerance ellipse of community-dwelling older adults. Sarcopenic patients showed greater rightward displacement, indicating more severe muscle wasting and dehydration.

Conclusions

Older hip fracture patients showed a distinct pattern on bioelectrical impedance vector analysis indicating frailty and malnutrition. Bioelectrical impedance vector analysis may effectively screen for body composition changes and nutritional status, supporting timely, multidisciplinary interventions.