Assessment of Skeletal Muscle Mass in Older People: Comparison Between 2 Anthropometry-Based Methods and Dual-Energy X-ray Absorptiometry

Objectives: Sarcopenia is a common geriatric syndrome, whose diagnosis implies the assessment of muscle mass. Dual-energy x-ray absorptiometry (DXA) is the reference method for clinical practice, but it is not universally available. We compared DXA with 2 anthropometry-based methods to assess muscle mass in older adults. Design: Cross-sectional. Setting: Ambulatory patients. Participants: 148 (87 female and 61 male) white older adults. Measurements: Mid-arm muscle circumference (MAMC), whole skeletal muscle mass estimated by the Lee's formula (eTSMM), and relative skeletal muscle index (RSMI). Results: Men and women did not differ for MAMC and RSMI, whereas eTSMM was higher (P<.001) in men. MAMC and eTSMM correlated with RSMI, in the whole sample as in men and women separately (P<.001). According to the McNemar test, the frequencies of older men and women with low muscle mass identified by eTSMM did not differ from those detected by RSMI (P=.066) at variance with MAMC. Using EWGSOP (European Working Group on Sarcopenia in Older People) criteria for RSMI as standard reference, the receiver operating characteristic (ROC) curves provided redefined cut-offs of reduced muscle mass: 18.6 cm in women and 22.3 cm in men for MAMC, and 17.7 kg in women and 28.3 kg in men for eTSMM. The areas under the ROC curves (AUCs) for MAMC were 0.882 in women (sensitivity 89%, specificity 84%) and 0.826 in men (sensitivity 94%, specificity 67%). The AUCs for eTSMM were 0.8913 in women (sensitivity 95%, specificity 81%) and 0.878 in men (sensitivity 97%, specificity 67%). No significant difference was found between the ROC curves of MAMC and eTSMM in both sexes. Conclusion: Two simple anthropometric methods, possibly used in every clinical setting, could be valuable screening tools for low muscle mass in older subjects. (C) 2018 AMDA - The Society for Post-Acute and Long-Term Care Medicine.