Validation of Segmental Multi-frequency Bioelectrical Impedance Analysis in Older Women with Characteristics of Sarcopenia

Abstract

Segmental multi-frequency bioelectrical impedance analysis (SMF-BIA) has been shown to be a valid, more portable, and less expensive alternative to dual energy x-ray absorptiometry (DXA) for the measurement of appendicular lean mass (ALM) in several populations. However, few studies have examined the validity of SMF-BIA specifically among populations of older women who are sarcopenic or dynapenic. PURPOSE: To investigate the accuracy of SMF-BIA for the measurement of ALM among sarcopenic and/or dynapenic older women. METHODS: Physical function, ALM, strength and anthropometric tests were performed to determine the presence of sarcopenia and/or dynapenia in a sample of older (72.3±4.6 years) women (n=25) using established sarcopenia classification criteria. Estimation of ALM using SMF-BIA and DXA were performed under standardized testing conditions. Both techniques were administered within the same hour with participants adequately hydrated, fasted, following urine elimination, and while wearing hospital scrubs. A Pearson correlation coefficient was used to determine a relationship between the two methods for ALM and agreement between the two techniques was assessed using a Bland-Altman plot method. RESULTS: A significant and strong correlation was observed between the two techniques with a Pearson’s correlation coefficient of 0.88 (95%CI: 0.75 to 0.95; P<0.001). The Bland Altman plot showed a mean difference of 0.5 kg and an indication of overall agreement between techniques. However, SMF-BIA overestimated ALM for one participant (-2.9kg, 95%CI -3.76 to -2.03) and underestimated ALM for another participant (1.8kg, 95%CI 0.98-2.71) compared to DXA. CONCLUSION: The findings indicate overall agreement between SMF-BIA and DXA for the estimation of ALM among older women with characteristics of sarcopenia, but SMF-BIA may overestimate or underestimate ALM in some individuals. These data suggest that SMF-BIA may be an acceptable alternative for the assessment of ALM in older women who have sarcopenia or dynapenia.