OBJECTIVE: To validate accelerometry based on its correlations with 6-minute walk distance (6MWD) and oxygen cost of walking as objective markers of walking limitations in multiple sclerosis (MS).

DESIGN: Cross-sectional.

SETTING: Laboratory and general community.

PARTICIPANTS: Ambulatory participants with MS (N=26) who resided in the local community.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: Patient Determined Disease Steps (PDDS) scale and Multiple Sclerosis Walking Scale-12 (MSWS-12); 6-minute walk test while wearing a portable metabolic unit for measuring the 6MWD and oxygen cost of walking; accelerometer during the waking hours of a 7-day period.

RESULTS: The average of total daily movement counts from the accelerometer correlated significantly and strongly with MSWS-12 scores (ρ=-.681, P=.001), PDDS scores (ρ=-.609, P=.001), 6MWD (ρ=.519, P=.003), and oxygen cost of walking (ρ=-.541, P=.002).

CONCLUSIONS: We provide evidence that further supports the validity of accelerometry as a measure of walking limitations in ambulatory persons with MS.