Cross-sectional and longitudinal correlations between the Arm Function in Multiple Sclerosis Questionnaire (AMSQ) and other outcome measures in multiple sclerosis

•The arm function in multiple sclerosis questionnaire (AMSQ) shows moderate correlations with established physician- and performance based outcome measures in multiple sclerosis (MS).•Strongest correlations were found between the AMSQ and the expanded disability status scale (EDSS), the 9-Hole peg test (9-HPT), the cerebellar functional system (FS) and the pyramidal FS.•Correlations were more pronounced in the cross-sectional cohort, compared to the longitudinal cohort. The Arm Function in Multiple Sclerosis Questionnaire (AMSQ) is the first validated disease specific patient-reported outcome measure (PROM) designed to assess upper extremity function in patients with multiple sclerosis (MS). To determine correlations between the AMSQ and established physician- and performance based outcome measures. In a cross-sectional cohort of 533 patients correlations between the AMSQ and the Expanded Disability Status Scale (EDSS), its functional systems, the 9-Hole Peg Test (9-HPT) and the Timed-25 Foot Walk (T25FW) were determined. Subgroup analyses were performed as well. Also, correlations were determined in 110 of 533 patients with available longitudinal data. Strongest correlations were found in the cross-sectional cohort between the AMSQ and the EDSS (β 0.60, p