Phase Angle as a predictor of motor function decline in children with Duchenne muscular dystrophy

Abstract

Background: Duchenne muscular dystrophy (DMD) is a prevalent X-linked recessive muscle degeneration disorder that involves the gradual loss of functional muscle mass. The Phase Angle (PhA) can indicate changes in cell membrane integrity and intercellular space. It has been recognized as a valuable tool for assessing disease severity and predicting patient outcomes. However, there is limited research on the application of PhA in children with neuromuscular diseases, including DMD. Objective: More biological indicators are needed to reflect clinical progress in DMD children. We specifically examined the correlation between segmental PhAs and motor function and evaluated the effectiveness of segmental PhAs as a measure for assessing motor function in DMD children Methods:A retrospective longitudinal cohort study of 399 boys with DMD in West China Second University Hospital (2016-2023) was performed. The correlation between PhA and motor function were analyzed through spearman correlation analysis. The predictive value of PhA and PhA combining age for lower limb motor function loss was analyzed by ROC curve. Results: The time of peak of PhAs are earlier than NNSA score (peak at 6-7years old). TR-PhA reaches its peak at 6 years old, while other PhAs reaches its peak at 5-6 years old and subsequently declines over time. There was a significant correlation between PhAs and the NSAA score, with the strongest correlation observed in leg PhA (r=0.753, P<0.001). PhAs in legs demonstrate the strongest correlation and highest predictive value for lower limb motor function loss(AUC from 0.725 to 0.863). Additionally, PhAs combined with age had more excellent predictive ability for lower limb function loss than PhAs((AUC from 0.929 to 0.951). Conclusion: 1）The phase Angle increases first and then decreases with the progression of DMD disease; the phase Angle changes earlier than motor function and presents a good correlation, which is a sensitive index to predict the progression of DMD disease. PhA could serve as a simple, fast, and non-invasive marker to predict the loss of lower limb motor function in DMD children.