Comparisons between dual-energy X-ray absorptiometry and bioimpedance devices for appendicular lean mass and muscle...

The purpose of this study was to compare single- and multi-frequency bioimpedance (BIA) devices against dual-energy X-ray absorptiometry (DXA) for appendicular lean mass (ALM) and muscle quality index (MQI) metrics in Hispanic adults. One hundred thirty-one Hispanic adults (18-55 years) participated in this study. ALM was measured with single-frequency bioimpedance analysis (SFBIA), multi-frequency bioimpedance analysis (MFBIA) and DXA. ALM_TOTAL (left arm + right arm + left leg + right leg) and ALM_ARMS (left arm + right arm) were computed for all three devices. Handgrip strength (HGS) was measured using a dynamometer. The average HGS was used for all MQI models (highest left hand + highest right hand)/2. MQI_ARMS was defined as the ratio between HGS and ALM_ARMS. MQI_TOTAL was established as the ratio between HGS and ALM_TOTAL. SFBIA and MFBIA had strong correlations with DXA for all ALM and MQI metrics (Lin's concordance correlation coefficient values ranged from 0·86 (MQI_MFBIA-ARMS) to 0·97 (Arms LM_SFBIA); all P < 0·001). Equivalence testing varied between methods (e.g. SFBIA v. DXA) when examining the different metrics (i.e. ALM_TOTAL, ALM_ARMS, MQI_TOTAL and MQI_ARMS). MQI_ARMS was the only metric that did not differ from the line of identity and had no proportional bias when comparing all the devices against each other. The current study findings demonstrate good overall agreement between SFBIA, MFBIA and DXA for ALM_TOTAL and ALM_ARMS in a Hispanic population. However, SFBIA and MFBIA have better agreement with DXA when used to compute MQI_ARMS than MQI_TOTAL.