Fatigue and gait speed in multiple sclerosis: Assessment and relationship

Abstract

Fatigue and gait impairment are two of the most common and disabling symptoms in patients with multiple sclerosis (PwMS). If on one side, the gait evaluation of PwMS is well established, on the other side, there is no consensus about which instrument is the most pertinent and reproducible to evaluate fatigue in PwMS [1] . The objectives of this study were: – to determine which fatigue scales is the most reproducible and; – to establish the associations between fatigue scales and the gait of PwMS. 59 PwMS with an EDSS score between 4 and 7 participated in this study. The fatigue was assessed with 2 main specific scales for PwMS: FSS and EMIF-SEP (separated in four subscales [physical, cognitive, social and psychological]). The gait was evaluated at a fast condition as described in previous study [2] . Two identical measures were conducted at one-week interval without therapeutic intervention. For the reproducibility evaluations a student t -test (for systematic error), intra-class correlation coefficients (ICC) and minimum detectable change (MDC95) were calculated. Finally, to evaluate the contribution of fatigue to PwMS’ gait velocity, a multi-linear regression model (stepwise-forward) was used. No systematic error was found for both fatigue scales. EMIF-SEP (ICC > 0.76) showed a better reliability than FSS (ICC = 0.69). In terms of agreement, the MDC95 score of the EMIF-SEP (MDC95: 17.86–22.09 point of percentage) was less than those founded for FSS (33.33 point of percentage). No correlation was found between fatigue scales including the EMIF-SEP subscales and the gait velocity. The EMIF-SEP and its subscales had better reproducibility scores than the FSS, suggesting that it is most adapted to test the effect of therapeutic interventions in PwMS’ fatigue. The fatigue assessed with questionnaires seems not to be associated with gait impairment. This result suggested that an independent approach should be taken into account to relief these two main symptoms of MS.