Diagnosis of sarcopenia by evaluating skeletal muscle mass by adjusted bioimpedance analysis validated with dual-energy X-ray absorptiometry.

This study aimed to adjust and cross-validate skeletal muscle mass measurements between bioimpedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) for the screening of sarcopenia in the community and to estimate the prevalence of sarcopenia in Hong Kong. Screening of sarcopenia was provided to community-dwelling older adults. Appendicular skeletal muscle mass (ASM) was evaluated by BIA (InBody 120 or 720) and/or DXA. Handgrip strength and/or gait speed were assessed. Diagnosis of sarcopenia was based on the 2019 revised Asian Working Group for Sarcopenia cut-offs. Agreement analysis was performed to cross-validate ASM measurements by BIA and DXA. Multiple regression was used to explore contribution of measured parameters in predicting DXA ASM from BIA. A total of 1587 participants (age = 72 ± 12 years) were recruited; 1065 participants were screened by BIA (InBody 120) with 18 followed up by DXA, while the remaining 522 participants were assessed by the BIA (InBody 720) and DXA. The appendicular skeletal muscle mass index (ASMI) evaluated by BIA showed a mean difference of 2.89 ± 0.38 kg/m2 (InBody 120) and 2.97 ± 0.45 kg/m2 (InBody 720) against DXA gold standard. A significant overestimation of muscle mass was measured by BIA compared with DXA (P < 0.005). BIA data were adjusted using prediction equation and mean difference reduced to -0.02 ± 0.31 kg/m2 in cross-validation. Prevalence of sarcopenia in older adults ≥65 ranged from 39.4% (based on ASMI by DXA) to 40.8% (based on predicted DXA ASMI from BIA). Low ASMI by DXA was found in 68.5% of the older adults screened. The percentage of older adults exhibited low handgrip strength ranged from 31.3% to 56%, while 49% showed low gait speed. Bioimpedance analysis was found to overestimate skeletal muscle mass compared with DXA. With adjustment equations, BIA can be used as a quick and reliable tool for screening sarcopenia in community and clinical settings with limited access to better options.

Cheng KY ，Chow SK ，Hung VW ，Wong CH ，Wong RM ，Tsang CS ，Kwok T ，Cheung WH ... -  《-》

Which is the best alternative to estimate muscle mass for sarcopenia diagnosis when DXA is unavailable?

Dual x-ray absorptiometry (DXA) is widely adopted to estimate muscle mass for research, but for daily practice is only available in a limited number of facilities. To elucidate if it is anthropometry or bioelectrical impedance analysis (BIA) the method more concordant with DXA in estimating muscle mass for sarcopenia diagnosis among older adults, and to investigate the impact of several cut-off points in sarcopenia frequency. 159 older adults (≥65 years) were included in a cross-sectional analysis. Sarcopenia was identified using the 2018 EWGSOP2 definition, plus previous definitions for muscle mass. Estimation of muscle mass by DXA (appendicular skeletal muscle mass (ASM) and ASM/height2), by BIA (skeletal muscle mass/height2 (SMM/height2) and skeletal muscle mass index (SMI)), and anthropometry (calf and mid-arm muscle circumferences (CC and MAMC, respectively)) was carried out, as well as measurements of handgrip strength and gait speed. Sarcopenia frequency varied from 5.0 to 42.1% depending on the method and cut-off point applied. All surrogate diagnostic criteria had a higher agreement with the DXA defined criterion ASM over ASM/height2. A substantial agreement was also found with BIA SMM/height2 (κ= 0.67), and with BIA SMI (κ= 0.65), and a moderate agreement with MAMC (κ= 0.42), p<0.001. Using the DXA ASM and ASM/height2 criteria as reference, CC showed a specificity of 100% and 94%, respectively. BIA is a suitable method to evaluate muscle mass in sarcopenia diagnosis when DXA is unavailable. Furthermore, CC showed to be a valid indicator to rule in the presence of sarcopenia.

Sousa-Santos AR ，Barros D ，Montanha TL ，Carvalho J ，Amaral TF ... -  《-》

Case finding for sarcopenia in geriatric inpatients: performance of bioimpedance analysis in comparison to dual X-ray absorptiometry.

Reiss J ，Iglseder B ，Kreutzer M ，Weilbuchner I ，Treschnitzer W ，Kässmann H ，Pirich C ，Reiter R ... -  《BMC Geriatrics》

Validating muscle mass cutoffs of four international sarcopenia-working groups in Japanese people using DXA and BIA.

The Asian Working Group for Sarcopenia (AWGS) 2019 recommended the use of dual-energy X-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA) to assess appendicular lean mass (ALM). AWGS, European Working Group on Sarcopenia in Older People 2 (EWGSOP2), Foundation for the National Institutes of Health Sarcopenia Project (FNIH), and International Working Group on Sarcopenia (IWGS) reported different cutoff values for sarcopenia. We aimed to validate these cutoff values in a Japanese population using DXA and two different devices of segmental multi-frequency BIA (MF-BIA). We examined the data of Japanese individuals aged 18-86 years using the DXA (n = 756) and two 8-electrode MF-BIA devices (InBody and TANITA MC) (n = 1884). To validate these cutoff values, we used a population aged 18-40 years, and calculated the 95% confidence intervals (CIs) of [mean-2SD]. In DXA, the 95%CIs of [mean-2SD] for ALM/Ht2 were 5.2-5.8 and 6.6-7.3 kg/m2 in women and men, respectively. The AWGS (<5.4 in women and <7.0 in men), and IWGS (≤5.67 in women and ≤7.23 in men) cutoffs were acceptable. Regarding TANITA MC, the 95%CIs of [mean-2SD] for ALM/Ht2 were 5.6-6.0 and 6.9-7.4 kg/m2 in women and men, respectively. The AWGS (<5.7 in women and <7.0 in men), EWGSOP2 (<6.0 in women and <7.0 in men), and IWGS cutoffs were acceptable. Regarding InBody, the 95%CIs of [mean-2SD] for ALM/Ht2 were 4.8-5.2 and 6.4-6.8 kg/m2 in young women and men, respectively. All cutoff values were too high compared to those measured by InBody. InBody and TANITA MC were highly correlated (P < 0.001), but the values by InBody were significantly lower than those by TANITA MC or DXA. Using Yamada's equation for InBody raw data, the AWGS, EWGSOP2, or IWGS cutoffs were acceptable. The BMI-adjusted muscle mass cutoff values were <0.60 and <0.82 m2 in women and men, respectively. We also obtained the 20th percentile in older adult population (ALM/Ht2 , <6.2 in women and <7.5 in men for TANITA MC; <5.4 in women and <7.0 in men for InBody). The AWGS and IWGS cutoffs were valid for DXA, and the AWGS, IWGS, and EWGSOP2 cutoffs were valid for TANITA MC in Japanese population. Because the prevalence of sarcopenia is too low particularly in women when using those criteria, the 20th percentile might be a good alternative criteria. If the ALM original InBody values are used, the cutoffs should be <5.0 kg/m2 in women and <6.6 kg/m2 in men.

Yamada Y ，Yamada M ，Yoshida T ，Miyachi M ，Arai H ... -  《-》

Two-megahertz impedance index prediction equation for appendicular lean mass in Korean older people.

Whole-body bioelectrical impedance analysis (BIA) has been accepted as an indirect method to estimate appendicular lean mass (ALM) comparable to dual-energy X-ray absorptiometry (DXA). However, single or limited frequencies currently used for these estimates may over or under-estimate ALM. Accordingly, there is a need to measure the impedance parameter with appendicular lean-specific across multiple frequencies to more accurately estimate ALM. We aimed to validate muscle-specific frequency BIA equation for ALM using multifrequency BIA (MF-BIA) with DXA as the reference. 195 community-dwelling Korean older people (94 men and 101 women) aged 70 ~ 92y participated in this study. ALM was measured by DXA and bioimpedance measures at frequencies of 5 kHz ~ 3 MHz were assessed for independent predictive variables. Regression analyses were used to find limb-specific frequencies of bioimpedance, to develop the ALM equations and to conduct the internal cross-validation. The six published equations and the final equation of MF-BIA were externally cross-validated. 195 participants completed the measurements of MF-BIA and DXA. Using bivariate regression analysis, the 2 MHz impedance index explained R2 = 91.5% of variability (P < 0.001) in ALM and predictive accuracy of standard error of estimate (SEE) was 1.0822 kg ALM (P < 0.001). Multiple stepwise regression analysis obtained in the development group had an adjusted R2 of 9.28% (P < 0.001) and a SEE of 0.97 kg ALM. The cross-validation group had no significant difference between the measured ALM and the predicted ALM (17.8 ± 3.9 kg vs. 17.7 ± 3.8 kg, P = .486) with 93.1% of R2 (P < 0.001) and 1.00 kg ALM of total error. The final regression equation was as follows: ALM = 0.247ZI@2 MHz + 1.254SEXM1F0 + 0.067Xc@5 kHz + 1.739 with 93% of R2 (P < 0.001), 0.97 kg ALM of SEE (Subjective Rating as "excellent" for men and "very good" for women). In the analysis of the diagnostic level for sarcopenia of the final regression, the overall agreement was 94.9% (k = 0.779, P < 0.001) with 71.4% of sensitivity, 98.8% of specificity, 91.3 of positive prediction value and 95.3% of negative prediction value. The newly developed appendicular lean-specific high-frequency BIA prediction equation has a high predictive accuracy, sensitivity, specificity, and agreement for both individual and group measurements. Thus, the high-frequency BIA prediction equation is suitable not only for epidemiological studies, but also for the diagnosis of sarcopenia in clinical settings.

Kim H ，Song KH ，Ambegaonkar JP ，Chung S ，Jeon K ，Jiang FL ，Eom JJ ，Kim CH ... -  《BMC Geriatrics》