Development of the Arm Function in Multiple Sclerosis Questionnaire-Short Form (AMSQ-SF): A static 10-item version

Assessing arm and hand function of multiple sclerosis (MS) patients is important as impaired functioning may impact daily activities and reduce quality of life.

A short-form of the Arm Function in Multiple Sclerosis Questionnaire (AMSQ), a recently developed patient-reported outcome measure containing 31 items, is developed to allow non-adaptive application.

Complete data from 690 patients with MS, recruited via outpatient clinics, a residential center or via a Dutch website aimed at MS patients, were included in the analyses. A graded response model was fit to these data to estimate item response theory (IRT) parameters, which were used to perform post hoc computerized adaptive test (CAT) simulations with a cutoff standard error of measurement (SEM) of 0.32. The optimal test length was determined by the correlation between the static short-form and full-length theta, the mean SEM, and the amount of patients reaching a satisfactory SEM in CAT simulations.

Based on five selection criteria (i.e. discrimination parameters, total information, times selected in CAT simulations, raw item means, and item content), 10 items were selected for inclusion in the short-form. The score on the final 10-item short-form correlated strongly with the full-length AMSQ and provided reliable ability estimations, indicating its usefulness instrument in research and clinical settings.