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Updated: May 29, 2026
Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy
Published on: January 12, 2019
Development of a functional assessment scale for ambulatory boys with Duchenne muscular dystrophy
Elaine Scott1, Michelle Eagle, Anna Mayhew
1Muscular Dystrophy Campaign, London, UK. elaines@muscular-dystrophy.org
Insights
The North Star Ambulatory Assessment is a reliable and practical clinical scale for measuring functional ability in ambulant boys with Duchenne muscular dystrophy. This assessment tool is quick to perform and suitable for high-functioning individuals.
Area of Science:
- Clinical assessment scale development
- Paediatric neuromuscular physiotherapy
- Duchenne muscular dystrophy research
Background:
- Duchenne muscular dystrophy (DMD) significantly impacts functional ability in ambulant boys.
- A need exists for a reliable clinical assessment scale tailored to this population.
- Multi-centre reliability studies are crucial for validating assessment tools in clinical practice.
Purpose of the Study:
- To develop a clinical assessment scale for functional ability in ambulant boys with Duchenne muscular dystrophy.
- To establish the multi-centre reliability of the developed scale within the UK.
Main Methods:
- Scale content was determined through focus groups and workshops with paediatric neuromuscular physiotherapists.
- A comprehensive manual and video resources were created, accompanied by training sessions.
- Inter-rater reliability was assessed by 17 physiotherapists, and intra-rater reliability by 5, using standardized videos.
Main Results:
- Very good strength of agreement was observed for total subject scores (consistency 0.95, absolute agreement ≥ 0.93).
- High test-retest reliability was demonstrated, with perfect agreement on most scale items between occasions.
- The scale proved practical for use in multiple centres.
Conclusions:
- The North Star Ambulatory Assessment (NSAA) is a practical and reliable clinical tool for Duchenne muscular dystrophy.
- The NSAA efficiently assesses functional ability in 10 minutes, incorporating timed tests and activity levels.
- The scale is suitable for evaluating high-functioning ambulant 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.
