Are Accelerometers and GPS Devices Valid, Reliable and Feasible Tools for Measurement of Community Ambulation after Stroke?

Abstract

Purpose: To determine validity, reliability and feasibility of accelerometers (ActivPAL™, Sensewear Pro2 Armband) and portable global positioning systems (GPS) (Garmin Forerunner 405CX) for community ambulation measurement after stroke. Methods: Fifteen community-dwelling stroke survivors attended two sessions; completing a 6-minute walk, treadmill walking, and 200-m outdoor circuit. Feasibility was determined by wearing devices over four days. Measures collected included step count, time spent walking, distance, energy expenditure and location. Intra-class correlation coefficients (ICC), Bland-Altman plots and absolute percentage of error (APE) were used to determine validity and reliability. Results: ActivPAL™ had excellent validity and reliability for most measures (ICC: 0.821-0.999, APE: 0%-11.1%), except for good-excellent findings at speeds < 0.42 m/s (ICC: 0.659-0.894, APE: 1.6%-11.1%). Sensewear had missing values for 23% of recordings and high error for all measures. GPS demonstrated excellent validity and reliability for time spent walking and step count (ICC: 0.805-0.999, APE: 0.9%-10%), and 100% accuracy for location. However, it was not valid or reliable for distance (ICC = -0.139, APE = 23.8%). All devices appeared feasible for community ambulation measurement with assistance for setup and data analysis. Conclusions: ActivPAL™ and Garmin GPS appear valid, reliable and feasible tools for community ambulation measurement after stroke, except for distance. Sensewear demonstrated poor validity and reliability when worn on the paretic arm.