Development and psychometric properties of the Multiple Sclerosis Knowledge Assessment Scale: Rasch analysis of a novel tool for evaluating MS knowledge.

BACKGROUND: Multiple sclerosis (MS)-related knowledge is an important evaluation metric for health education interventions. However, few MS knowledge assessment tools are currently available for use. OBJECTIVES: This study aims to develop a reliable and valid Multiple Sclerosis Knowledge Assessment Scale (MSKAS) for use in the MS community and the general public. METHODS: The MSKAS was developed using a Delphi study methodology and was administered to participants in the first open enrolment of the Understanding Multiple Sclerosis (UMS) online course. Rasch analysis was used to examine its psychometric properties and develop the final scale. RESULTS: Experts from across the MS community participated in the development of the MSKAS, resulting in an initial scale of 42 items. Five hundred and forty-three UMS participants completed the MSKAS; 89% were female and 30% were people with MS. The final unidimensional 22-item scale has a person separation index of 2.16, a person reliability index of 0.82, an item separation index of 11.19, and a Cronbach's alpha (kr-20) test reliability of 0.87. CONCLUSION: The MSKAS is a unidimensional scale with good construct validity and internal consistency. The MSKAS has the potential to be useful for the assessment of MS knowledge in research and clinical practice.