Development of a functional assessment scale for ambulatory boys with Duchenne muscular dystrophy.

Background And Purpose: The aims of this study were to develop a clinical assessment scale to measure functional ability in ambulant boys with Duchenne muscular dystrophy and to determine the reliability of the scale in multiple centres in the UK.

Methods: Focus groups and workshops were held with experienced paediatric neuromuscular physiotherapists to determine scale content. A manual was prepared with accompanying videos, and training sessions were conducted. A total of 17 physiotherapists from participating centres used the videos to determine inter-rater reliability. Five determined the intra-rater reliability.

Results: Strength of agreement for these groups based on total subject scores was very good (0.95 and ≥ 0.93 for consistency and absolute agreement, respectively). Test-retest ability was high, with perfect agreement between occasions for all but two items of the scale.

Conclusions: Our study indicates that the North Star Ambulatory Assessment is practical and reliable. It takes only 10 minutes to perform and incorporates both universally used timed tests as well as levels of activities, which allow assessment of high-functioning boys with Duchenne muscular dystrophy.