Validation and psychometric properties of the Multiple Sclerosis Autonomy Score (MSAS) in a French cohort: The FOCAL-MS 2 study

BACKGROUND: Multiple sclerosis (MS) is a leading cause of non-traumatic neurological disability in young adults, with profound implications for personal autonomy, mental health, and social participation. As no Patient-Reported Outcome Measure adequately captures patient autonomy, we developed the Multiple Sclerosis Autonomy Scale (MSAS). The FOCAL-MS 2 study aims to confirm the psychometric properties of the MSAS score. METHODS: Patients included between 01/02/2024 and 19/04/2024 were routinely followed for 12 months throughout France. Health Care Professionals (HCPs) sent patients the 36-item MSAS questionnaire to complete before out-patient visits. Patients also completed the MSAS upon inclusion, 15 (D15), 30 (D30), and 360 (D360) days later. Validation included internal consistency, reliability, unidimensionality, multidimensionality, and construct validity. RESULTS: A total of 199 patients (74.4% females; age 49.7 years) were included. The MSAS presented good internal consistency at inclusion (Cronbach's alpha = 0.845) and good test-retest reliability (intra-class correlation coefficient = 0.72 at D15 and 0.75 at D30). As each dimension was required to maintain consistency, one item was removed to improve the instrument's properties. CONCLUSION: The 35-question MSAS is a valid, consistent, and reliable tool to assess patient autonomy in MS and satisfies patients' and HCPs' needs.