Continuous Remote Assessment of Multiple Sclerosis Disability over One Year: The UCSF Fitrims Study
Objectives: To evaluate the feasibility of continuous remote activity monitoring for 1 year in a cohort of patients with multiple sclerosis (MS) and to analyze associations of change in average daily step count (STEPS) with standard clinical and disability metrics.
Methods: The UCSF FITRiMS (Fitbit Remote monitoring in MS) study enrolled 95 adults with relapsing or progressive MS and who were able to walk at least 2 minutes with or without an assistive device. Participants were asked to wear a Fitbit Flex device for 1-year. Clinic-based and patient-reported outcomes were assessed at baseline and 1 year follow-up, including: Expanded disability status scale (EDSS), Timed-25 Foot walk (T25FW) and MSWS-12 (12-Item MS scale).
Results: Overall, 79 (83.2% retention) participants completed the year-long study; 9 withdrew and 7 were lost to follow-up. On average, the Fitbit Flex provided valid step data for 3 weeks per month per individual. Participants with greater disability demonstrated lower STEPS over the year. For the cohort as a whole, there was no significant change in STEPS, longitudinal slope assessed via mixed model linear regression with time as an interaction term, (p=0.117) over the year. In participants with baseline STEPS below 4,766 (cohort median), the odds of disability worsening (clinically meaningful change in EDSS) over 1 year was 6.7x higher (CI: 2.21 – 22.92, p=0.001) if the initial EDSS was >4, and 9.4x higher (CI: 3.18 – 32.41, p<0.001) if the initial EDSS was >6. A decrease in STEPS over 1 year was associated with worsening in clinic-based (T25FW) and patient-reported (MSWS-12) measures of ambulation (p<0.001 for each).
Conclusions: 1) Continuous remote activity monitoring is feasible in people with MS over 1 year, 2) a low baseline STEPS (below 4,766 steps/day) substantially increases risk for clinically meaningful decline 1 year later; and 3) decreased STEPS is associated with worsening on clinic-based and patient-reported walking disability measures.