The Arm Function in Multiple Sclerosis Questionnaire (AMSQ): development and validation of a new tool using IRT methods.

Purpose: We developed the Arm Function in Multiple Sclerosis Questionnaire (AMSQ) to measure arm and hand function in MS, based on existing scales. We aimed at developing a unidimensional scale containing enough items to be used as an itembank. In this study, we investigated reliability and differential item functioning of the Dutch version.