title: Detection of gait and postures using a miniaturized triaxial accelerometer-based system: accuracy in patients with mild to moderate Parkinson's disease.
abstract: OBJECTIVE
  To examine whether gait and postures can accurately be detected with a single small body-fixed device in patients with mild to moderate Parkinson's disease (PD).
  
  
  METHODS
  Results of a triaxial accelerometer-based method were evaluated against video observation scores (criterion measure). Study 1: Subjects performed basic mobility-related activities (walking, lying, sitting, standing) in a fixed and free sequence. Study 2: Subjects were monitored while doing similar activities as in study 1 and while doing usual domestic activities.
  
  
  METHODS
  Study 1: Standardized set-up in a movement laboratory. Study 2: Home environment.
  
  
  METHODS
  (N=37) Study 1: Patients with PD (n=32; mean age +/- SD, 67.3+/-6.6y; mean disease duration +/- SD, 6.1+/-3.4y). Study 2: Patients with PD (n=5; mean age +/- SD, 76.0+/-7.3y; mean disease duration +/- SD, 3.8+/-4.7y).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The degree of correspondence between the monitor and the video observation for the duration of each activity. Overall agreement, sensitivity, specificity, and positive predictive values were calculated.
  
  
  RESULTS
  Study 1: Overall agreement ranged between 69.8% and 90.8% (fixed sequence) and 57.5% and 96.9% (free sequence). Study 2: Overall agreement ranged between 60.0% and 89.2%. Lying, sitting (home), and walking were detected most accurately with mean sensitivity varying from 81.7% to 99.9%. Lower values were found for sitting (laboratory), standing, and shuffling.
  
  
  CONCLUSIONS
  This triaxial monitor system is a practical and valuable tool for objective, continuous evaluation of walking and postures in patients with mild to moderate PD. Detection of sitting and standing requires further fine-tuning.
authors.affiliation: University Medical Center Groningen, University of Groningen, The Netherlands. baukdijkstra@hotmail.com
authors.forename: Baukje
authors.initials: B
authors.lastname: Dijkstra
authors.forename: Ype P
authors.initials: YP
authors.lastname: Kamsma
authors.forename: Wiebren
authors.initials: W
authors.lastname: Zijlstra
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D020734:Parkinsonian Disorders / Q000175:diagnosis* / Q000503:physiopathology; D026741:Physical Therapy Modalities; D011187:Posture; D015203:Reproducibility of Results