P248 Feasibility, accuracy and reproducibility of the ultrasound measurement of psoas muscle compared to bioelectrical impedance analysis for the evaluation of skeletal muscle mass in patients with IBD

Abstract

Abstract Background Sarcopenia is characterized by the loss of muscle mass and it is a strong predictor of disability and poor outcomes in several chronic gastrointestinal diseases such as inflammatory bowel diseases (IBD). Therefore, it is useful to evaluate muscle mass in patients with chronic gastrointestinal diseases at risk for sarcopenia. Radiological evaluation of muscle mass is obtained with computed tomography (CT), magnetic resonance (MRI) and bioelectrical impedance (BIA). We aimed at assessing the feasibility, reproducibility and diagnostic accuracy of ultrasound (US) measurement of psoas muscle thickness adjusted for body mass index (BMI) compared to skeletal muscle mass (SMM) evaluated with BIA normalized to height2 in the quantification of muscle mass among patients with IBD. Methods We enrolled a total of 86 consecutive patients with IBD (males 68.6%, mean age 50.4 ± 17.6, 7.4% with Crohn’s disease) who underwent US evaluation of psoas muscle thickness and BIA during the same day. US measurement (Philips Epiq, Bothell, USA) was performed by two sonographers, blind to each other. BIA was performed with the Seca mBCA 525 (Hamburg, Germany). A cut-off of 6.68 and 8.97 of SMM normalized to height2 was considered as normal value for women and men respectively. Sensitivity, specificity, positive and negative predictive values(PPV and NPV), positive and negative likelihood ratios (LR+ andLR−) were calculated, all with the respective 95% confidence inter-vals (95% CI). The reproducibility between the US operators was evaluated by intra-class correlation coefficient(ICC) for the quantitative variables of psoas muscle. The study was approved by our local ethics committee and partially funded by the Italian Ministry of Health. Results US psoas muscle thickness measurement was feasible in all the 86 enrolled patients. There was a significant correlation between US measurement and BIA with a Pearson r coefficient of 0.54 (p= <0.0001). Among men a cut off of 108.18 cmxkg/m*2 showed a sensitivity of 93.5% and a specificity of 53,6% in the detection of low SMM at BIA (Figure 1). Among women a cut off of 66.9 cmxkg/m*2 showed a sensitivity of 78.5% and a specificity of 69.2% in the detection of low SMM at BIA (Figure 2). Reproducibility among the operators had an ICC of 0.95 (CI 0.93-0.96). Conclusion Sarcopenia is a prognostic factor of poor outcomes in IBD, therefore it is important to identify patients at risk for it. Nowadays, assessment of muscle mass and eventually sarcopenia relies on radiological techniques (CT/MRI and BIA). At this purpose we propose a simple, non-ionizing, fast and reproducible US technique that compared to BIA showed a high sensitivity and thus can be used in clinical ractice to screen for muscle mass reduction in IBD patients.