RESEARCH ARTICLE Development of a Functional Assessment Scale for Ambulatory Boys with Duchenne Muscular Dystrophy Elaine Scott 1 * , Michelle Eagle 2 , Anna Mayhew 2 , Jenny Freeman 3 , Marion Main 4 , Jennie Sheehan 5 , Adnan Manzur 6 , Francesco Muntoni 6 & The North Star Clinical Network for Paediatric Neuromuscular Disease † 1 Muscular Dystrophy Campaign, London, UK 2 Institute of Human Genetics, Newcastle, UK 3 University of Sheffield, Sheffield, UK 4 Great Ormond Street Hospital, London, UK 5 Evelina Children’s Hospital, London, UK 6 Dubowitz Neuromuscular Centre, Institute of Child Health, UCL, London, UK Abstract 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 phy- siotherapists 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 univer- sally used timed tests as well as levels of activities, which allow assessment of high-functioning boys with Duchenne muscular dystrophy. Copyright © 2011 John Wiley & Sons, Ltd. Received 27 January 2011; Revised 21 May 2011; Accepted 26 June 2011 Keywords ambulant; assessment; Duchenne muscular dystrophy *Correspondence Elaine Scott, MPhil, MCSP, c/o Muscular Dystrophy Campaign, 61 Southwark Street, London SE1 0HL, UK. Email: elaines@muscular-dystrophy.org † The North Star Clinical Network for Paediatric Neuromuscular Disease: Collaborators (53): Manzur A.Y., Muntoni F., Robb S., Main M., Kemp J. (Great Ormond Street Hospital, London), Scott E. (Muscular Dystrophy Campaign, London), Bushby K., Straub V., A. Sarkozy, E. Strehle, R. Venkateswaran, Eagle E., Mayhew A. (Institute of Human Genetics, Newcastle), Roper H., McMurchie H., Grace A. (Heartlands Hospital, Birmingham), Spinty S., Peachey G., Shillington S. (Alder Hey Children’s Hospital, Liverpool), Quinlivan R., Groves L. (Robert Jones and Agnes Hunt Royal Orthopaedic Hospital, Oswestry), Wraige E., Jungbluth H., Sheehan J., Spahr R. (Evalina Children's Hospital, London), Hughes I., Bateman E., Cammiss C. (Royal Manchester Children's Hospital), Childs A.M., Pallant L., Psyden K. (Leeds General Infirmary), Baxter P. (Sheffield Children's Hospital), Naismith K., Keddie A. (King's Cross Hospital, Dundee), Horrocks I., McWilliam R., Di Marco M. (Yorkhill Children's Hospital, Glasgow), Hartley L., Sheen B., Fenton-May J. (University Hospital Wales, Cardiff), Jardine P., Majumdar A., Jenkins L. (Frenchay Hospital, Bristol), Chow G., Miah A. (Queen's Medical Centre University Hospital, Nottingham), de Goede C. (Preston Royal Hospital), Thomas N., Geary M., 101 Physiother. Res. Int. 17 (2012) 101–109 © 2011 John Wiley & Sons, Ltd.