Daily step patterns may help track disability in progressive MS and provide a fuller picture of disability than occasional clinic assessments, a study found.
Researchers analysing more than two years of data from 529 people found that those with greater disability or walking impairment generally took fewer daily steps.
The differences were most pronounced during the late morning and afternoon. Daily step patterns were also closely associated with clinic-based measures of MS disability.
The University of California, San Francisco team studied adults aged 18 to 65 with primary or secondary progressive MS who had taken part in the Phase 3 SPI2 trial.
Participants wore wrist-worn Fitbit devices that continuously recorded their steps during the 27-month study, while neurological assessments were carried out every three months.
The original trial tested whether high-dose biotin could ease disability or improve walking speed compared with a placebo in progressive MS, but did not meet its main goal.
For the new analysis, researchers examined participants’ step counts minute by minute and accounted for periods when the devices were likely not being worn.
They compared the data with the Expanded Disability Status Scale, or EDSS, which assesses walking, balance and other areas of neurological function affected by MS.
They also used the Timed 25-Foot Walk, or T25FW, which measures mobility by recording how long someone takes to walk 25 feet.
Higher EDSS scores, indicating greater disability, and longer T25FW times, indicating slower walking, were consistently associated with fewer steps, particularly during the late morning and afternoon.
Compared with people with EDSS scores of 3 to 3.5, which indicate disability without the need for walking aids, midday step counts were around 50 per cent lower among those with an EDSS score of 6.
Midday steps were around 70 per cent lower among those with an EDSS score of 6.5. Scores of 6 or 6.5 indicate a level of disability requiring at least one walking aid, such as a cane or crutches.
People who took at least eight seconds to complete the T25FW also recorded around 50 per cent fewer midday steps than those who completed it in less than six seconds.
EDSS scores were more strongly associated with daily step patterns than T25FW results, although combining both measures provided the most information for predicting variations in step counts throughout the day.
Researchers suggested this could be because EDSS captures several aspects of neurological function, while the T25FW focuses specifically on walking speed.
Of the neurological functions assessed through EDSS, walking ability, motor function and coordination explained the greatest variation in daily step patterns, with walking ability showing the strongest association.
The findings suggest continuous step-count profiles from wearable devices could complement clinic-based measures by providing information about how mobility varies during everyday life.
Researchers said the approach could potentially help identify when mobility differences are most apparent and inform the timing of mobility-focused interventions.
