Ultrasound measurement of rectus femoris muscle thickness as a quick screening test for sarcopenia assessment

Introduction: Sarcopenia is a geriatric syndrome related to loss of muscle mass and function, leading to disability, frailty and higher mortality. According to European Working Group on Sarcopenia in Older People (EWGSOP) the diagnosis of sarcopenia requires the assessment of muscle mass, muscle force and function, that is time-consuming and not easily at hand in everyday clinical practice. We propose the B-mode ultrasound measurement of muscle thickness as a quick screening test to assess the presence of sarcopenia. Methods: A cross-sectional study was realized, 119 patients (average age 82 years, 50.4% females) from the Department of Internal Medicine of the University Hospital of Siena (Italy) were enrolled. The diagnosis of sarcopenia was assessed according to EWGSOP criteria. Rectus femoris muscle (RFM) thickness (in cm) was measured by ultrasound B-mode scanning. Sensibility and specificity of the test was evaluated and Receiver Operating Analysis (ROC) was performed to assess the accuracy of the test. Results: Average RFM thickness was 0.78 ± 0.26, significantly lower in sarcopenic patients (0.55 ± 0.2 vs. 0.9 ± 0.3; Mann-Whitney; p < 0.001) and females (0.7 ± 0.3 vs 0.86 ± 0.3; Mann-Whitney; p < 0.001). The cut-off point of 0.7 cm for females and 0.9 cm for males was established as a threshold to assess the presence of sarcopenia by ultrasound. Sensibility of ultrasound measurement of RFM thickness was 100%, specificity 64%, positive predictive value (PPV) 64.3% and negative predictive value (NPV) 100%. ROC analysis was performed in order to quantify how accurately RFM thickness can discriminate between sarcopenia and non-sarcopenia state. AUC for all patients was 0.9 and after a comparative analysis for gender higher values for males (0.94 vs. 0.92) were observed. Conclusion: We suggest a screening test for sarcopenia based on the ultrasound measurement of RFM thickness, as a not invasive and easy to perform method even in elderly patients with functional or cognitive impairment.