Bio-Electrical Impedance Analysis: A Valid Assessment Tool for Diagnosis of Low Appendicular Lean Mass in Older Adults?

Abstract

BackgroundThe diagnosis of sarcopenia is essential for early treatment of sarcopenia in older adults, for which assessment of appendicular lean mass (ALM) is needed. Multi-frequency bio-electrical impedance analysis (MF-BIA) may be a valid assessment tool to assess ALM in older adults, but the evidences are limited. Therefore, we validated the BIA to diagnose low ALM in older adults.MethodsALM was assessed by a standing-posture 8 electrode MF-BIA (Tanita MC-780) in 202 community-dwelling older adults (age ≥ 55 years), and compared with dual-energy X-ray absorptiometry (DXA) (Hologic Inc., Marlborough, MA, United States; DXA). The validity for assessing the absolute values of ALM was evaluated by: (1) bias (mean difference), (2) percentage of accurate predictions (within 5% of DXA values), (3) the mean absolute error (MAE), and (4) limits of agreement (Bland–Altman analysis). The lowest quintile of ALM by DXA was used as proxy for low ALM (< 22.8 kg for men, < 16.1 kg for women). Sensitivity and specificity of diagnosing low ALM by BIA were assessed.ResultsThe mean age of the subjects was 72.1 ± 6.4 years, with a BMI of 25.4 ± 3.6 kg/m2, and 71% were women. BIA slightly underestimated ALM compared to DXA with a mean bias of −0.6 ± 1.2 kg. The percentage of accurate predictions was 54% with a MAE of 1.1 kg, and limits of agreement were −3.0 to + 1.8 kg. The sensitivity for ALM was 80%, indicating that 80% of subjects who were diagnosed as low ALM according to DXA were also diagnosed low ALM by BIA. The specificity was 90%, indicating that 90% of subjects who were diagnosed as normal ALM by DXA were also diagnosed as normal ALM by the BIA.ConclusionThis comparison showed a poor validity of MF-BIA to assess the absolute values of ALM, but a reasonable sensitivity and specificity to recognize the community-dwelling older adults with the lowest muscle mass.

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“…The accelerated aging of the world’s population is estimated as follows: by 2050, 16% of the world’s population will be over 65 years of age and the number of people over 80 years of age will increase by three times [ 31 ]; therefore, the incidence of sarcopenia will also increase. It is considered that more than 50% of people over 80 years of age have sarcopenia [ 36 ].…”

“…To limit these shortcomings, the patients were instructed not to consume large amounts of water and not to exert sustained efforts 2–3 h before the measurements [ 66 ]. Moreover, the skeletal muscle index values that define sarcopenia are different, depending on the device and the gender of the patient (the limit points for men—6.76 kg/m 2 and for women—5.28 kg/m 2 , [ 31 ]). According to Walowski et al [ 67 ], the values are between 7.70 and 9.20 kg/m 2 in men and 5.67–7.40 kg/m 2 in women.…”

“…Appendicular skeletal muscle mass (ASM) and skeletal muscle index (SMI) were determined using the formula of Janssen et al (ASM/height squared) [ 29 ]. Published research claims that the MF-BIA method (also used as diagnostic method for sarcopenia in our study) is a useful tool [ 30 ], with a specificity of 90%, in evaluating elderly adults [ 31 ]. The Asia Working Group on Sarcopenia (2019) suggested that SMI (men, <7.0 kg/m 2 ; women, <5.7 kg/m 2 ) [ 32 ] and sarcopenic obesity were defined as low SMI plus a high percentage of body fat (PBF) (men: low SMI and PBF ≥ 25%; women: low SMI and PBF ≥ 30%) [ 33 , 34 ].…”

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“…BIA is a method that uses electrical conductivity to estimate fat and lean body mass [ 13 , 50 ]. A study comparing BIA and DEXA concluded that BIA had 80% sensitivity and 90% specificity for detecting appendicular lean mass, compared with DEXA [ 54 ], further proving its potential in sarcopenia detection. This method is affordable and easy to use.…”

“…Anthropomorphic measurements can be used as a tool to screen at-risk individuals if other imaging modalities are not available or cost-prohibitive [ 13 , 50 ]. This test can be administered in the clinic by conducting a measurement of the calf circumference or mid-arm muscle circumference, which can be used to grossly assess nutritional status and screen for sarcopenia [ 54 , 55 ].…”