OBJECTIVES: This study aimed at evaluating the psychometric properties of a PROM dedicated at identifying the social disabilities / autonomy of patients with MS, questionnaire has been developed in collaboration with MS patient associations.

METHODS: The psychometric validation of the questionnaire evaluating patient autonomy in multiple sclerosis (MS) has been performed by empirically validating the initial theoretical conceptual model composed of 131 questions clustered in 13 dimensions targeting a 36-items short form. Varimax principal component analysis was performed. Cronbach alpha curves and Rasch models were used to determine internal validity, and item reduction Multitrait analysis was conducted.

External validity of the reduced questionnaire has been evaluated using ANOVA with class on disease severity proxy estimated using the SymptoMScreen questionnaire.

RESULTS: 715 patients were included in the study from July 2022 to December 2022 and 653 questionnaires were analyzable for the validation, 83.6% of patients were women, 31.6% had been diagnosed with MS for less than 5 years, and 63.2% had a SymptoMScreen score <30.

Floor effects (<10%) were marginally present. Because of too few patients, the Student dimension was removed. Confirmatory factor analysis supported a 10-domain structure; item-scale Spearman’s correlations ranged between 0.30-0.65 (convergent validity), and all items correlated highest with their intended scale, except one item for which correlation of the intended scale was very close.

Internal consistency reliability was good for all domains, Cronbach's alpha ranging from 0.77 to 0.85.

Correlations between PROM domains and external SymptoMScreen measures that were expected to correlate were moderate-strong for all domains (known groups validity).

CONCLUSIONS: Results support the use of the PROM to evaluate the autonomy of patients suffering from MS. A confirmatory study, using the validated questionnaire, will be initiated soon.