title: Objective measurement of functional upper-extremity movement using accelerometer recordings transformed with a threshold filter.
abstract: OBJECTIVE
  The consensus is that the most important outcome for rehabilitation is functional activity in the life situation. Constraint-Induced Movement Therapy, a new treatment that transfers in-clinic gains to the life situation, demands objective measurement of real-world movement. However, direct, objective, and accurate measures of arm use in the real world are not available. Previous attempts to use accelerometry to measure extremity movement have failed because of unacceptable variability. This problem has been addressed here by use of a threshold filter.
  
  
  METHODS
  Nine stroke patients and 1 healthy individual wearing accelerometers were videotaped while they carried out their usual activities at home or in the clinic; the duration of their arm, torso, and ambulatory movements was judged by 2 observation teams. In addition, 11 college students performed 5 standardized activities of daily living for varying durations in the laboratory. The accelerometer data were transformed; the raw value recorded for a given epoch was set to a constant if it exceeded a low threshold.
  
  
  RESULTS
  The threshold-filtered recordings measured the duration of movement accurately and with very little variability. Correlations between the threshold-filtered recordings and the observer ratings of the duration of arm, torso, and ambulatory movements were 0.93, 0.93 and 0.99, respectively; the corresponding correlations for the raw values were -0.17, 0.34, and 0.85.
  
  
  CONCLUSIONS
  These results present initial evidence for the validity of threshold-filtered accelerometer recordings for objectively measuring the amount of real-world upper-extremity movement as an index of treatment outcome for rehabilitation patients.
authors.affiliation: Department of Psychology, University of Alabama at Birmingham, 35294-1170, USA. guswatte@uab.edu
authors.forename: G
authors.initials: G
authors.lastname: Uswatte
authors.forename: W H
authors.initials: WH
authors.lastname: Miltner
authors.forename: B
authors.initials: B
authors.lastname: Foo
authors.forename: M
authors.initials: M
authors.lastname: Varma
authors.forename: S
authors.initials: S
authors.lastname: Moran
authors.forename: E
authors.initials: E
authors.lastname: Taub
mesh_terms: D000328:Adult; D001132:Arm / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement; D017063:Outcome Assessment, Health Care; D012016:Reference Values; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D013997:Time Factors; D014743:Videotape Recording