Performance of the Upper Limb Module—A Reliable and Valid Evaluation for Chinese Patients with Duchenne Muscular Dystrophy

Background Duchenne muscular dystrophy is a genetic disease leading to progressive muscle weakness and degeneration. Effective assessment tool is needed to allow monitoring of progress to guide the management. This study assessed the reliability and validity of the Performance of Upper Limb (PUL) Module when used in patients with Duchenne Muscular Dystrophy (DMD). MethodsTotal thirty-three Chinese DMD patients were included. Twenty-five video-recorded PUL Module version 1.3 assessments were performed for the recruited patients with three raters evaluated the same recorded video for inter-rater reliability and evaluated the same performance one month later for intra-rater reliability. Construct validity was assessed correlating the PUL Module scores with the patients’ age, their forced vital capacity (N=25) and their Hammersmith motor scale scores (N=25) performed on the same day. ResultsThe intra-rater and inter-rater reliability (ICC 0.92 - 0.99), internal consistency (Cronbach’s alpha 0.97 - 0.99) and known groups validity (AUC 0.97) of PUL module were excellent. PUL was negatively correlated with age (r = -0.912), and positively correlated with the forced vital capacity (r = 0.87) and the Hammersmith motor scale (r = 0.84). The findings confirm the high reliability and validity of PUL module, and its high clinical relevancy in monitoring the deteriorating upper limb motor performance that strongly correlated with the lung function and generalized motor performance as age increased in DMD. ConclusionThis first study of PUL module in Chinese patients with DMD confirmed that it is a reliable valid tool to monitor clinical progress and outcome for DMD.