Correlation between segmental Phase Angles and motor function of DMD children and predictive value of Phase angels for lower limb motor function loss

Abstract

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：we investigated the relationship between Phase Angle (PhA) and motor function in children with DMD. 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 Method: 399 DMD patients were divided into loss of lower limb motor function group (n = 57) and preserve lower limb motor function group (n = 342). 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. Result: TR-PhA reaches its peak at 6 years old, while other PhAs reaches its peak at 5-6years 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). ROC curve was used and showed that PhAs (LA, RA, LL, RL, TR, and whole) can predict the loss of lower limb function in DMD children (AUC from 0.725 to 0.863).The corresponding cut-off PhA values were 2.55°, 2.95°, 2.65°, 2.55°, 4.25°, and 2.85°, respectively. 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: The time of peak of PhAs are earlier than NNSA score (peak at 6-7years old). PhAs in legs demonstrate the strongest correlation and highest predictive value for lower limb motor function loss. PhA could serve as a simple, fast, and non-invasive marker to predict the loss of lower limb motor function in DMD children.