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Published on: July 14, 2023
Body composition characteristics in patients with inflammatory myopathy based on bioelectrical impedance analysis
Zheng Wei1, Guo Yanlin1, Luo Jing1
1Department of Neurology, Chongqing Key Laboratory of Major Neurological and Mental Disorders, Neurology Key Laboratory of Chongqing Education Commission of China, Chongqing Key Laboratory of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing; and Department of Rare Disease, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Objectives:
To investigate body composition features in idiopathic inflammatory myopathy (IIM) using bioelectrical impedance analysis (BIA) and evaluate their clinical, diagnostic and follow-up value.
Methods:
This study included 103 patients with inflammatory myopathy over a 6-year period, excluding 15 cases, resulting in a final cohort of 88 IIM patients. Clinical assessments and BIA were performed. Healthy controls and patients with amyotrophic lateral sclerosis (ALS) were independently recruited as separate comparison groups.
Results:
IIM patients showed reduced muscle mass (SMM: 20.9±4.4 vs. 23.4±4.8, p=0.001), elevated ECW/TBW ratio (ECW/TBW total (ETT): 0.398±0.015 vs. 0.381±0.007, p<0.001), and decreased phase angle (PhARA: 3.50 [2.92, 4.50]° vs. 5.15 [4.50, 5.62]°, p<0.001; PhALA: 3.55 [2.84, 4.43]° vs. 5.03 [4.48, 5.42]°, p<0.001). These features correlated with disease severity, inflammation, and nutritional status. Compared to ALS, IIM patients had more marked ECW retention (ETT: 0.397±0.0145 vs. 0.389±0.0110, p=0.001) and impaired membrane integrity (PhARA: 3.450±0.99° vs. 4.295±1.44°, p=0.014; PhALA: 3.500 [2.850, 4.400]° vs. 4.400 [3.875, 4.925]°, p=0.003). Body composition demonstrated substantial potential for diagnostic application (XGBoost model: specificity 85.00%, sensitivity 88.46%), and more importantly, may serve as a valuable tool for disease management.
Conclusions:
BIA technology provides important novel disease characteristics for IIM patients, which are closely related to traditional clinical features and demonstrate significant diagnostic and management potential.
