Timed Up-and-Go and 2-Minute Walk Test in patients with multiple sclerosis with mild disability: reliability, responsiveness and link with perceived fatigue

BACKGROUND: Mobility limitations are frequent in patients with multiple sclerosis (MS), and could already be present in patients with so-called mild neurological disability (Expanded Disability Status Scale≤4). Assessing mobility in these patients is therefore of paramount importance. Timed Up-and-Go Test (TUG) and 2-Minute Walk Test (2MWT) are two clinically feasible tests which reliability and responsiveness are unknown among these patients. Whether fatigue, which is the number one symptom among these patients, is linked to these limitations remains unknown. AIM: The aim of this study was to explore the intrarater reliability and minimal detectable change (MDC95), as an index of responsiveness, of TUG and 2MWT. To explore their link with perceived fatigue among patients with MS. DESIGN: Cross-sectional observational study, including two measures. SETTING: Two university hospital outpatient centers. POPULATION: Patients (N.=63, 49 seen twice) with MS with mild disability (Expanded Disability Status Scale≤4). METHODS: 2MWT and TUG were performed twice in one occasion, and repeated 2 weeks later. Modified fatigue impact scale (MFIS) was used to assess fatigue. Intraclass coefficient correlations were calculated for immediate and 2-week reliability. MDC95 were computed. Correlations between mobility indices and fatigue were explored using Spearman's ρ. RESULTS: Mobility was impaired in comparison to normative values (2MWT: -4.9% from normative distance; TUG: +32% from normative time). The immediate reliability was excellent for both the 2MWT (ICC=0.98) and TUG (ICC=0.98). Reliability at 2 weeks was excellent for 2MWT (ICC=0.95) and very good for TUG (ICC=0.90). MDC95 were respectively 20m (2MWT) and 1.3s (TUG). Both measures were significantly weakly correlated to total MFIS (ρ=-0.37 and 0.39, respectively; P<0.01). CONCLUSIONS: The 2MWT and TUG are highly reliable and responsive in the assessment of respectively the walking capacity and general mobility of patients with MS with mild disability. Mobility impairments are linked to perceived fatigue among these patients. CLINICAL REHABILITATION IMPACT: TUG and 2MWT are easy to administer and could be reliably used in so called mildly disabled patients with MS to assess mobility limitation.