Evidence of Construct Validity for the Modified Mental Fatigue Scale When Used in Persons with Cerebral Palsy.

Introduction: Fatigue impacts negatively on everyday activities in individuals with cerebral palsy (CP). More knowledge is needed about how mental fatigue is manifested in this target group. The purpose of this study was to gather evidence about the validity of the modified Mental Fatigue Scale (m-MFS) in adults with CP. Methods: Mixed sequential exploratory design. The respondents were ten persons aged 22-56 with CP (MACS I-II). Results: The respondents perceived the m-MFS as easy to read and understand. Its structure was characterised as straightforward and the text of the rating options was deemed to assist identification with life situations. Very good agreement was seen between the respondents' and the instrument designers' intended meaning for the items in the m-MFS; the weighted kappa was 0.92. Conclusion: This study showed evidence of construct validity, based on response processes and content, for use of the modified MFS in adults with CP.