title: Objective Gait and Balance Impairments Relate to Balance Confidence and Perceived Mobility in People With Parkinson Disease.
abstract: BACKGROUND
  Body-worn, inertial sensors can provide many objective measures of balance and gait. However, the objective measures that best reflect patient perception of mobility disability and clinician assessment of Parkinson disease (PD) are unknown.
  
  
  OBJECTIVE
  The purposes of this study were: (1) to determine which objective measures of balance and gait are most related to patient perception of mobility disability and disease severity in people with PD and (2) to examine the effect of levodopa therapy on these correlates.
  
  
  METHODS
  This was an experimental correlation study.
  
  
  METHODS
  One hundred four people with idiopathic PD performed 3 trials of the Instrumented Stand and Walk Test (ISAW) in the "on" and "off" medication states. The ISAW consists of quiet standing (30 seconds), gait initiation, straight walking (7 m), and turning (180°), yielding 34 objective measures of mobility from body-worn inertial sensors. Patient perception of mobility disability was assessed with the Activities-specific Balance Confidence (ABC) scale and the mobility subscale of the Parkinson's Disease Questionnaire (PDQ-39). Disease severity was assessed with the Unified Parkinson's Disease Rating Scale, part III (motor UPDRS). Spearman correlations were used to relate objective measures of mobility to patient perception and disease severity.
  
  
  RESULTS
  Turning speed, gait speed, and stride length were most highly correlated to severity of disease and patient perception of mobility disability. The objective measures of mobility in the off-medication state were more indicative of patient perception of mobility disability and balance confidence compared with on-medication state measures.
  
  
  CONCLUSIONS
  Causation is an inherent problem of correlation studies.
  
  
  CONCLUSIONS
  Physical therapists should evaluate mobility in people with PD in the off-medication state because the off-medication state is more related to disease severity and patient perception of mobility disability than the on-medication state mobility. Assessment and treatment of mobility in people with PD should target specific measures (ie, turning, gait speed, and stride length) because these measures best reflect patients' quality of life and balance confidence.
authors.affiliation: C. Curtze, PhD, Department of Neurology, School of Medicine, Oregon Health & Science University, 3181 Sam Jackson Park Rd, Portland, OR 97239-3098 (USA). curtze@ohsu.edu.
authors.forename: Carolin
authors.initials: C
authors.lastname: Curtze
authors.affiliation: J.G. Nutt, MD, Department of Neurology, School of Medicine, Oregon Health & Science University.
authors.forename: John G
authors.initials: JG
authors.lastname: Nutt
authors.affiliation: P. Carlson-Kuhta, PhD, Department of Neurology, School of Medicine, Oregon Health & Science University.
authors.forename: Patricia
authors.initials: P
authors.lastname: Carlson-Kuhta
authors.affiliation: M. Mancini, PhD, Department of Neurology, School of Medicine, Oregon Health & Science University.
authors.forename: Martina
authors.initials: M
authors.lastname: Mancini
authors.affiliation: F.B. Horak, PhD, Department of Neurology, School of Medicine, Oregon Health & Science University, and Veterans Affairs Portland Health Care System, Portland, Oregon.
authors.forename: Fay B
authors.initials: FB
authors.lastname: Horak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D015259:Dopamine Agents / Q000627:therapeutic use*; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
chemical_list: D015259:Dopamine Agents; D007980:Levodopa