Day-to-day reliability, agreement and discriminative validity of measuring walking-related performance fatigability in persons with Multiple Sclerosis

Abstract

Background: Day-to-day reliability and cut-off values to detect abnormal walking fatigability (WF) remain to be investigated in persons with multiple sclerosis (pwMS). Methods: In all, 49 pwMS (mean Expanded Disability Status Scale (EDSS) ± standard deviation (SD): 3.3 ± 1.9) and 28 matched healthy controls (HC) performed the six-minute walking test (6MWT) on two different days to determine day-to-day reliability (intraclass correlation coefficient (ICC)) and limits of agreement (LOA) for five different equations of WF. Objective: To examine day-to-day reliability, agreement and discriminative validity for measuring WF. Results and conclusion: WF expressed as the ratio between the first and sixth minute had the best day-to-day reliability (ICC’s range of 0.76–0.95 and 0.60–0.86, respectively) in both pwMS and HC, while LOA were 15% and 7%, respectively. Ecological validity and clinical importance should be further investigated.