ABSTRACT
Disability measures in multiple sclerosis (MS) rely heavily on ambulatory function, and current metrics fail to capture potentially important variability in walking behavior. We sought to determine whether remote step count monitoring using a consumer-friendly accelerometer (Fitbit Flex) can enhance MS disability assessment. 99 adults with relapsing or progressive MS able to walk ≥2-min were prospectively recruited. At 4 weeks, study retention was 97% and median Fitbit use was 97% of days. Substudy validation resulted in high interclass correlations between Fitbit, ActiGraph and manual step count tally during a 2-minute walk test, and between Fitbit and ActiGraph (ICC = 0.76) during 7-day home monitoring. Over 4 weeks of continuous monitoring, daily steps were lower in progressive versus relapsing MS (mean difference 2546 steps, p < 0.01). Lower average daily step count was associated with greater disability on the Expanded Disability Status Scale (EDSS) (p < 0.001). Within each EDSS category, substantial variability in step count was apparent (i.e., EDSS = 6.0 range 1097-7152). Step count demonstrated moderate-strong correlations with other walking measures. Lower average daily step count is associated with greater MS disability and captures important variability in real-world walking activity otherwise masked by standard disability scales, including the EDSS. These results support remote step count monitoring as an exploratory outcome in MS trials.
Subject(s)
Accelerometry/methods , Disability Evaluation , Multiple Sclerosis, Chronic Progressive/diagnosis , Multiple Sclerosis, Relapsing-Remitting/diagnosis , Telemedicine/methods , Walking , Biomechanical Phenomena , Female , Humans , Male , Middle Aged , Monitoring, Ambulatory/methods , Multiple Sclerosis, Chronic Progressive/physiopathology , Multiple Sclerosis, Relapsing-Remitting/physiopathology , Prospective Studies , Reproducibility of Results , Walking/physiologyABSTRACT
BACKGROUND AND PURPOSE: The clinical predictors of health-related quality of life (HRQoL) in multiple sclerosis (MS) have mainly been studied in patients with long-standing disease. The objective of this study was to investigate the longitudinal association among HRQoL and clinical characteristics in early MS. METHODS: Relapsing MS patients within 12 months of clinical onset were enrolled in a neuroprotection trial of riluzole versus placebo as an add-on to weekly interferon with up to 36 months of follow-up. Serial clinical measures included Short Form-36 (SF-36) as the measure of HRQoL, MS Functional Composite (as a measure of disability), Modified Fatigue Impact Scale, Patient Health Questionnaire-9 (as a measure of depression) and a cognitive battery. Multivariable linear regression analyses assessed cross-sectional associations. Mixed model regressions with mutual adjustments were used to assess the longitudinal association of HRQoL components and clinical, cognitive and demographic variables. RESULTS: Forty-three patients were enrolled within 7.5 ± 4.9 months of clinical onset (72% female, mean age 36 years). The baseline severity of fatigue and depression predicted subsequent changes in SF-36 Physical Component Summary (PCS) (P values of 0.001 and 0.021, respectively). In longitudinal analyses, changes in disability and depression were associated with changes in SF-36 PCS (P values of 0.002 and 0.009, respectively), whereas changes in cognitive function and fatigue were associated with changes in SF-36 Mental Component Summary (P values of 0.037 and 0.001, respectively). A 1-unit increase in MS Functional Composite was associated with a 7.1-point increase in SF-36 PCS (95% CI, 2.6-11.6). CONCLUSIONS: Fatigue, depression, cognition and disability are independently associated with HRQoL in early MS.
