Structural Validity and Inter-rater Reliabitiliy of the Ataxia Trunk, Lower And Upper Extremity Scale (ATLAS)

Ataxia is a neurological disorder affecting coordination, caused by damage to the cerebellum, brainstem, or related pathways. It can be hereditary (e.g., Friedreich's ataxia) or acquired (e.g., multiple sclerosis, stroke). Though rare, ataxia significantly impacts quality of life and independence. Treatments are limited and mainly focus on multidisciplinary rehabilitation. Accurate assessment is essential, yet current tools like Scale for the Assessment and Rating of Ataxia (SARA) have limitations. This study aims to validate a new scale, named the Ataxia Trunk, Lower And upper extremity Scale (ATLAS), through Rasch analysis, to develop a shorter, reliable version. It will assess internal consistency, construct validity, and inter-rater reliability.

For the valitdity part, statistics will be used (1) to see if the different items of the scale are indeed different and complementary to each other, and (2) to compare the results of this scale with other scales already known and valid (SARA, Trunk Impairment Scale (TIS) and Functional Impairment Measurement(FIM)). Secondly, the investigators would like to know whether ATLAS is reliable. In this particular case, the reliability being assessed is inter-rater reliability, i.e. whether all raters give the same score on the items performed by the patient. To carry out such a study, 64 people will be needed to achieve these goals. Each person will complete the 20 items of the ATLAS scale, those of a trunk motor capacity assessment (TIS), and will evaluate his or her functional independence (FIM).