title: Using Commercial Activity Monitors to Measure Gait in Patients with Suspected iNPH: Implications for Ambulatory Monitoring.
abstract: OBJECTIVE
  This study seeks to validate the use of activity monitors to detect and record gait abnormalities, potentially identifying patients with idiopathic normal pressure hydrocephalus (iNPH) prior to the onset of cognitive or urinary symptoms.
  
  
  METHODS
  This study compared the step counts of four common activity monitors (Omron Step Counter HJ-113, New Lifestyles 2000, Nike Fuelband, and Fitbit Ultra) to an observed step count in 17 patients with confirmed iNPH.
  
  
  RESULTS
  Of the four devices, the Fitbit Ultra (Fitbit, Inc., San Francisco, CA) provided the most accurate step count. The correlation with the observed step count was significantly higher (p<0.009) for the Fitbit Ultra than for any of the other three devices.
  
  
  CONCLUSIONS
  These preliminary findings suggest that existing activity monitors have variable efficacy in the iNPH patient population and that the MEMS tri-axial accelerometer and algorithm of the Fitbit Ultra provides the most accurate gait measurements of the four devices tested.
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine.
authors.forename: Shiv
authors.initials: S
authors.lastname: Gaglani
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine.
authors.forename: Jessica
authors.initials: J
authors.lastname: Moore
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine.
authors.forename: M Ryan
authors.initials: MR
authors.lastname: Haynes
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine.
authors.forename: Jamie B
authors.initials: JB
authors.lastname: Hoffberger
authors.affiliation: Department of Neurosurgery, The Johns Hopkins University School of Medicine ; Department of Radiation Oncology, The Johns Hopkins University School of Medicine.
authors.forename: Daniele
authors.initials: D
authors.lastname: Rigamonti
keywords: activity monitor; idiopathic normal pressure hydrocephalus; inph