Anthropometric parameters as marker of sarcopenia

Introduction. The rare detection of sarcopenia (SP) in patients with rheumatoid arthritis (RA) is associated with the low informative value of available screening methods and muscle strength assessing, and limited availability of instrumental body composition determination. Therefore, it is necessary to develop affordable screening methods for SP with good sensitivity and specificity. Aim. To establish the sensitivity and specificity of mid-upper arm circumference (MUAC) and calf circumference (CC) measurements as methods for assessing muscle mass in comparison with data obtained using dual-energy X-ray absorptiometry (DXA) for detection of SP in women with RA. Materials and methods. 201 women (mean age 59.3 ± 9.0 years) with confirmed RA were examined by a standard clinical examination, as well as measurement of MUAC and CC. Body composition analysis using DXA was done. The sensitivity and specificity of anthropometric indicators for SP screening were determined using ROC-analysis. Results. The appendicular muscle index (AMI) was determined using DXA. AMI < 5.5 kg/m2 was detected in 37 (18.4%) patients. MUAC and CC had a direct correlation with AMI (r = 0.56 and r = 0.52, respectively, p < 0.001). MUAC ≤ 26.0 cm and CC ≤ 33.8 cm were determined, which had the optimal ratio of sensitivity and specificity for low muscle mass screening (67.6% and 84.2%, respectively, for MUAC; 73.0% and 76.2%, respectively, for CC). The area under the curve (AUC) for the MUAC was 0.822 (95% confidence interval (CI) 0.762–0.873, p < 0.001), and for the CC – 0.789 (95% CI 0.762–0.844, p < 0.001). Simultaneous use of the both indicators had a sensitivity of 62.2% and a specificity of 90.2%. Conclusions. In patients with RA, MUAC or CC had comparable diagnostic significance and can be used for SP screening. Simultaneous use of two measurements did not improve the diagnostic value. Further evaluation of available screening methods is needed.