Reliability and validity of an activity monitor (IDEEA) in the determination of temporal-spatial gait parameters in individuals with cerebral palsy.

This study evaluated within- and between-session reliability and validity of temporal-spatial gait parameters derived from the intelligent device for energy expenditure and activity (IDEEA) activity monitor (Minisun, Fresno, CA) in subjects with cerebral palsy, using three-dimensional gait analysis (3-DGA) as the criterion standard. Twenty-five subjects with cerebral palsy (mean age 14.1 years, range 8-23) and 30 control subjects (mean age 14.2 years, range 7-24) completed two 3-DGA, 1 week apart with simultaneous IDEEA data collection. The IDEEA had lower within-session reliability than the 3-DGA for both groups, indicated by greater measurement errors and wider repeatability values for all temporal-spatial parameters. Between-session reliability of 3-DGA was high for both groups with intra-class correlation coefficients (ICC) >0.80. The IDEEA monitor showed high between-session reliability for control subjects (ICC 0.71-0.89), but lower reliability in subjects with cerebral palsy, particularly for walking velocity and stride length (ICC 0.53 and 0.62, respectively). Validity comparison between IDEEA and 3-DGA measures using Bland Altman 95% limits of agreement showed a measurement bias, with the IDEEA over-estimating step and stride length and underestimating cadence in both subject groups compared to 3-DGA. The 95% limits of agreement were smaller in controls (step +/-0.20 m; stride +/-0.27 m; walking velocity +/-0.28 m/s) than in subjects with cerebral palsy (step +/-0.36 m; stride +/-0.37 m; velocity +/-0.58 m/s). Modifications may be necessary to improve the reliability and validity of the IDEEA in children, particularly for use in neurological conditions.