Reliability of spatial-temporal gait parameters during dual-task interference in people with multiple sclerosis. A cross-sectional study

Purpose: To evaluate the reliability and minimum detectable change (MDC) of spatial-temporal gait parameters in subjects with multiple sclerosis (MS) during dual tasking. Method: This cross-sectional study involved 25 healthy subjects (mean age 49.9±15.8 years) and 25 people with MS (mean age 49.2±11.5 years). Gait under motor-cognitive and motor-motor dual tasking conditions was evaluated in two sessions separated by a one-day interval using the GAITRite® Walkway System. Test-retest reliability was assessed using intraclass correlation coefficients (ICCs), standard errors of measurement (SEM), and coefficients of variation (CV). MDC scores were computed for the velocity, cadence, step and stride length, step and stride time, double support time, the % of gait cycle for single support and stance phase, and base of support. Results: All of the gait parameters reported good to excellent ICCs under both conditions, with healthy subject values of >0.69 and MS subject values of >0.84. SEM values were always below 18% for both groups of subjects. The gait patterns of the people with MS were slightly more variable than those of the normal controls (CVs: 5.88-41.53% vs 2.84-30.48%). Conclusions: The assessment of quantitative gait parameters in healthy subjects and people with MS is highly reliable under both of the investigated dual tasking conditions