Agreement between single-frequency bioimpedance analysis and dual energy x-ray absorptiometry varies based on sex and...

Bioimpedance analysis (BIA) and dual energy X-ray absorptiometry (DXA) are commonly utilized for total and segmental body composition assessment, but the agreement between these methods varies. Group (i.e., constant error [CE]) and individual error (i.e., standard error of estimate [SEE] and 95% limits of agreement [LOAs]) of single-frequency BIA were determined in apparently healthy men and women (n = 28 and 45, respectively) when using DXA as a reference method. It was hypothesized that single-frequency BIA would provide lower error for the estimation of total and segmental FFM than FM and BF%. The CE for many of the total and segmental body composition comparisons revealed statistically significant (all P < .05) mean differences (FM_TOTAL, FM_LEGS, FFM_TOTAL, FFM_ARMS, FFM_LEGS, FFM_TRUNK, BF%_TOTAL and BF%_ARMS for both sexes as well as FM_TRUNK and BF%_TRUNK for women and FM_ARMS and FM_LEGS for men). Although there were significant CEs for many comparisons, the individual error (i.e., SEEs and 95% LOAs) for total and segmental FFM were small whereas FM and BF% were large. Furthermore, the individual error tended to be larger for men than women when estimating FM and BF%, which is likely attributed to the larger segmental mass of men. This finding indicates the agreement between single-frequency BIA and DXA varies based on sex and segmental mass. Consequently, single-frequency BIA can be used for total and segmental FFM, but is not recommended for FM and BF%.