Accuracy of segmental multi-frequency bioelectrical impedance analysis for assessing whole-body and appendicular fat mass and lean soft tissue mass in frail women aged 75 years and older

European Journal of Clinical Nutrition (2013) 67, 395–400 & 2013 Macmillan Publishers Limited All rights reserved 0954-3007/13 www.nature.com/ejcn ORIGINAL ARTICLE Accuracy of segmental multi-frequency bioelectrical impedance analysis for assessing whole-body and appendicular fat mass and lean soft tissue mass in frail women aged 75 years and older M Kim and H Kim BACKGROUND/OBJECTIVE: We aimed to examine the accuracy of segmental multi-frequency bioelectrical impedance analysis (SMF-BIA) for the assessment of whole-body and appendicular fat mass (FM) and lean soft tissue mass (LM) in frail older women, using dual-energy X-ray absorptiometry (DXA) as a reference method. SUBJECTS/METHODS: All 129 community-dwelling Japanese frail older women with a mean age of 80.9 years (range, 75–89 years) from the Frailty Intervention Trial were recruited. The agreements between SMF-BIA and DXA for whole-body and appendicular body composition were assessed using simple linear regression and Bland–Altman analysis. RESULTS: High coefficients of determination (R2) for whole-body FM (R2 ¼ 0.94, s.e. of estimate (SEE) ¼ 1.2 kg), whole-body LM (R2 ¼ 0.85, SEE ¼ 1.4 kg), and appendicular FM (R2 ¼ 0.82, SEE ¼ 1.1 kg) were observed between SMF-BIA and DXA. The R2 coefficient for appendicular LM was moderate (R2 ¼ 0.76, SEE ¼ 0.8 kg). Bland–Altman plots demonstrated that there was systematic (constant) bias (that is, DXA minus SMF-BIA) with overestimation of whole-body FM (bias ¼  1.2 kg, 95% confidence interval (CI) ¼  1.5 to  0.1) and underestimation of whole-body LM (bias ¼ 2.1 kg, 95% CI ¼ 1.8–2.3) by SMF-BIA. Similar, the appendicular measurements also demonstrated systematic bias with overestimation of appendicular FM (bias ¼  0.3 kg, 95% CI ¼  0.5 to  0.1) and underestimation of whole-body LM (bias ¼ 1.5 kg, 95% CI ¼ 1.4–1.7) by SMF-BIA. In addition, the individual level accuracy demonstrated a non-proportional bias for whole-body LM (r ¼ 0.08, P ¼ 0.338) and appendicular FM (r ¼ 0.07, P ¼ 0.413). CONCLUSIONS: SMF-BIA had acceptable accuracy for the estimation of whole-body and appendicular FM and LM in frail older women, although SMF-BIA underestimated LM and overestimated FM relative to DXA. European Journal of Clinical Nutrition (2013) 67, 395–400; doi:10.1038/ejcn.2013.9; published online 6 February 2013 Keywords: body composition; bioelectrical impedance analysis; sarcopenia; frailty INTRODUCTION Frailty is an important and common geriatric syndrome that is described as a status of increased vulnerability resulting from the loss of complexity in resting dynamics involving multiple physiological systems with advancing age.1 The prevalence of frailty increases with age, from 3.9% at 65–74 years to 11.6% at 75–84 years and to 25% in people older than 85 years. In addition, frailty is more prevalent in women than in men.1 Sarcopenia is a loss of skeletal muscle mass and size that occurs with aging.2 Although many definitions of sarcopenia have been reported,3–5 current definitions focus on loss of appendicular skeletal muscle mass as well as low muscle strength and low physical performance.6 The European Working Group on Sarcopenia in Older People consensus definition of sarcopenia is based on three stages: the presarcopenia stage involves low muscle mass with normal muscle strength and physical performance; the sarcopenia stage involves low muscle mass and either diminished muscle strength or physical performance; and severe sarcopenia combines all three factors.6 Several pathophysiological overlaps between sarcopenia and frailty have been observed.7 Thus, age-related loss in muscle mass and strength are a major component in the development of frailty in the elderly.8,9 Moreover, frailty is associated with a decline in muscle mass and quality and a parallel increase in fat mass (FM).10 Measurement of body composition, including FM and muscle mass in older populations provide important information about their nutritional status. Therefore, the understanding of the body composition of frail elderly populations is an important part of clinical assessment with a goal of optimal prevention and treatment strategies. Dual-energy X-ray absorptiometry (DXA) is an accepted method for the estimation of whole-body and segmental body fat and fatfree mass (FFM), which includes lean soft tissues and bone minerals.11–13 However, DXA has disadvantages for use in clinical settings, such as the high cost of equipment, risk of radiation exposure and lack of access to instruments. For clinical use, bioelectrical impedance analysis (BIA) has been used as an attractive alternative method.4,14,15 BIA is a portable, noninvasive, easy to use and convenient method for the patient, and it is also relatively inexpensive compared with other methods.16 Of the BIA devices developed over the years, segmental multi-frequency (SMF)-BIA devices have advantages Research Team for Promoting Independence of the Elderly, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan. Correspondence: Dr M Kim, Research Team for Promoting Independence of the Elderly, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan. E-mail: Author contributions: Both authors designed the study together. MK developed the study concept and design, analysed and interpreted the data, and prepared the manuscript. HK recruited subjects, assisted with statistical analysis and reviewed the manuscript for accuracy. Received 17 September 2012; revised 19 December 2012; accepted 21 December 2012; published online 6 February 2013 Body composition estimation in the frail older women M Kim and H Kim 396 over single-frequency BIA devices (50 kHz).17–19 SMF-BIA avoids the problems encountered in single-frequency BIA by employing both low- and high-frequency electric currents.20 In recent years, SMF-BIA has been shown to be valid in the estimation of body composition using DXA as a reference standard.21–23 However, these results were obtained from analysis of healthy populations. To our knowledge, SMF-BIA has not been evaluated in the assessment of total and appendicular body composition in a specifically targeted frail elderly population. Therefore, the aim of this study was to examine the accuracy of SMF-BIA for the assessment of whole-body and appendicular body composition using DXA as a reference method in frail Japanese women aged 75 years and older. MATERIALS AND METHODS Subjects The subjects were 129 community-dwelling Japanese frail older women with a mean age of 80.9 years (range, 75–89 years). The study population was recruited from participants in the Frailty Intervention Trial (clinical trials registry, number: JMA-IIA00069). The baseline assessment was conducted on 1835 women aged 75 and older at the Tokyo Metropolitan Institute of Gerontology. Three hundred thirty-one were defined as frail, according to Fried’s frailty phenotype with the presence of three or more of following criteria: weight loss (...truncated)