Walking fatigability indices correspond with perception of changes in gait speed and quality during an instrumented 6-minute walking test in people with multiple sclerosis

Background: People with MS (pwMS) present changes in gait speed and quality during a 6-min walking test (6MWT). It is unknown whether these changes are clinically meaningful. Objective: To examine the relationships between pwMS-perceived changes in gait speed and quality with walking fatigability indices. Methods: Forty-five pwMS (EDSS: 4.0; 51 ± 11 years) performed the 6MWT. Sensor-based fatigability indices were calculated by comparing gait quality and the distance walked between the first/last minute of the 6MWT. Perceived changes in speed, smoothness, balance, ankle, knee and hip movement, attention, spasticity and pain were reported after the 6MWT using a questionnaire (Likert-type). The minimal important change (MIC) was calculated using an anchor-based approach. Spearman's rank correlations (pwMS-perceived changes x fatigability indices) were calculated. Results: More than half of pwMS reported changes in speed, smoothness, balance, or ankle position after the 6MWT. Significant MICs were found for most gait quality fatigability indices, as well as significant correlations with perceived changes, particularly for distance, speed, cadence, stride length, double support, step duration variability, and toe-off angle. Conclusion: PwMS perceived changes in gait speed and quality. The MIC values complement existing cut-off scores, facilitating the identification of walking fatigability and its use in clinical trials.