Reliability of the North Star Ambulatory Assessment in a multicentric setting

Neuromuscul Disord. 2009 Jul;19(7):458-61. doi: 10.1016/j.nmd.2009.06.368. Epub 2009 Jun 23.


The aim of this study was to investigate the suitability of the North Star Ambulatory Assessment as a possible outcome measure in multicentric clinical trials. More specifically we wished to investigate the level of training needed for achieving a good interobserver reliability in a multicentric setting. The scale was specifically designed for ambulant children with Duchenne Muscular Dystrophy and includes 17 items that are relevant for this cohort. Thirteen Italian centers participated in the study. In the first phase of the study we provided two training videos and an example of the scale performed on a child. After the first session of training, all the 13 examiners were asked to send a video with an assessment performed in their centre and to score all the videos collected. There were no difficulties in performing the items and in obtaining adequate videos with a hand held camera but the results showed a poor interobserver reliability (<.5). After a second training session with review and discussion of the videos previously scored, the same examiners were asked to score three new videos. The results of this session had an excellent interobserver reliability (.995). The level of agreement was maintained even when the same videos were rescored after a month, showing a significant intra-observer reliability (.95). Our results suggest that the NSAA is a test that can be easily performed, completed in 10 min and can be used in a multicentric setting, providing that adequate training is administered.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • Child, Preschool
  • Cohort Studies
  • Data Interpretation, Statistical
  • Disability Evaluation*
  • Exercise Therapy / methods
  • Exercise Tolerance / physiology
  • Humans
  • Italy
  • Leg / physiopathology
  • Male
  • Mobility Limitation*
  • Muscle, Skeletal / physiopathology
  • Muscular Dystrophy, Duchenne / diagnosis*
  • Muscular Dystrophy, Duchenne / rehabilitation*
  • Observer Variation
  • Outcome Assessment, Health Care / methods*
  • Physical Therapy Modalities
  • Predictive Value of Tests
  • Reproducibility of Results
  • Video Recording
  • Walking / physiology*