Comparison of Self-Reported vs Objective Measures of Long-Term Community Ambulation in Lower Limb Prosthesis Users

Abstract

ObjectiveTo determine normal variation in walking metrics in a population of lower limb amputees who use lower limb prostheses over a 6-month period and to provide a means to interpret clinically meaningful change in those community walking metrics. DesignProspective cohort study monitoring walking behavior and subjective and objective measures of activity. SettingVeterans Administration and university amputee clinics. Participants86 individuals with lower limb amputation who use protheses. InterventionsStepWatch activity monitor tracked subjects’ walking for 24 weeks; Global Mobility Change Rating collected weekly. Main Outcome MeasuresAssociation between change in Global Mobility Change Rating and change in any of the walking metrics. ResultsWalking metrics including step count, cadence, cadence variability, and walking distance in a population of lower limb prosthesis users were obtained. There was a high correlation in the walking metrics indicating higher function with higher functional classification level (K-levels) but also substantial overlap in all metrics and a very weak correlation between subject-reported activity level and objective measures of walking performance. ConclusionThe overlap in walking metrics with all K-levels demonstrates that no single metric measured by StepWatch can determine K-level with 100% accuracy. As previously demonstrated in other populations, subjects’ interpretations of their general activity level was inaccurate, regardless of their age or activity level. Objective measures of walking appear to provide a more accurate representation of patients’ activity levels in the community than self-report. Therefore, objective measures of walking are useful in supporting K-level determinations. However, clinicians cannot rely on a single metric to determine K-level.