Assessment of total and regional bone mineral density using bioelectrical impedance vector analysis in elderly population

This study aimed to investigate the relationship between bone mineral density (BMD) and height-adjusted resistance (R/H), reactance (Xc/H) and phase angle (PhA). A total of 61 male and 64 female subjects aged over 60 years were recruited from middle Taiwan. The R and Xc were measured using Bodystat Quadscan 4000 at a frequency of 50 kHz. BMD at the whole body, L2-L4 spine, and dual femur neck (DFN), denoted as BMDTotal, BMDL2-L4, and BMDDFN, were calculated using a Hologic DXA scanner. The R-Xc graph was used to assess vector shift among different levels of BMD. BMD was positively correlated with Xc/H and negatively correlated with R/H (p<0.001). The General Linear Model (GLM) regression results were as follows: BMDTotal=1.473-0.002 R/H+0.007 Xc/H, r=0.684; BMDL2-L4=1.526-0.002 R/H+0.012 Xc/H, r=0.655; BMDDFN=1.304-0.002 R/H+Xc/H, r=0.680; p<0.0001. Distribution of vector in the R-Xc graph was significantly different for different levels of BMDTotal, BMDL2-L4 and BMDDFN. R/H and Xc/H were correlated with BMD in the elderly. The linear combination of R/H and Xc/H can effectively predict the BMD of the whole body, spine and proximal femur, indicating that BIVA may be used in clinical and home-use monitoring tool for screening BMD in the elderly in the future.