title: Determinants of objectively measured physical functional performance in early to mid-stage Parkinson disease.
abstract: BACKGROUND
  Parkinson disease (PD) may lead to functional limitations through both motor and nonmotor symptoms. Although patients with advanced disease have well-documented and profound functional limitations, less is known about the determinants of function in early to mid-stage disease where interventions may be more likely to benefit and preserve function.
  
  
  OBJECTIVE
  The objective of the current study was to identify motor, cognitive, and gait determinants of physical functional performance in patients with early to mid-stage PD.
  
  
  METHODS
  This was a secondary analysis of cross-sectional baseline data from a randomized clinical trial of exercise.
  
  
  METHODS
  The study was performed at a tertiary academic medical center.
  
  
  METHODS
  The study included 121 patients with early to mid-stage PD.
  
  
  METHODS
  Our functional performance outcomes included the following: the Continuous Scale Physical Functional Performance Test (CS-PFP; primary outcome); the Timed Up and Go test (TUG); and Section 2 (Activities of Daily Living) of the Unified Parkinson's Disease Rating Scale (UPDRS). Explanatory variables included measures of disease severity, motor function, cognitive function, balance, and gait. Stepwise linear regression models were used to determine correlations between explanatory variables and outcome measures.
  
  
  RESULTS
  In our regression models, the CS-PFP significantly correlated with walking endurance (Six-Minute Walk Test; r(2) = 0.12, P < .0001), turning ability (360° Turn Test; r(2) = 0.03, P = .002), attention (Brief Test of Attention; r(2) = 0.01, P = .03), overall cognitive status (Mini-Mental State Examination; r(2) = 0.01, P = .04), and bradykinesia (timed tapping; r(2) = 0.02, P = .02). The TUG significantly correlated with walking speed (5-Meter Walk Test; r(2) = 0.33, P < .0001), stride length (r(2) = 0.25, P < .0001), turning ability (360° turn, r(2) = 0.05, P = .0003), and attention (r(2) = 0.016, P = .03). Section 2 of the UPDRS was significantly correlated with endurance (r(2) = 0.09, P < .0001), turning ability (r(2) = 0.03, P = .001), and attention (r(2) = 0.01, P = .03).
  
  
  CONCLUSIONS
  Gait, motor, and cognitive function all contribute to objectively measured global functional ability in mild to moderate PD. Subjectively measured functional activity outcomes may underestimate the impact of both motor and nonmotor symptoms.
authors.affiliation: Department of Neurology, Academic Office 1, Mailstop B185, PO Box 6511, Aurora, CO 80045∗. Electronic address: benzi.kluger@ucdenver.edu.
authors.forename: Benzi M
authors.initials: BM
authors.lastname: Kluger
authors.affiliation: Department of Neurology, School of Medicine, University of Colorado, Aurora, CO(†).
authors.forename: R Preston
authors.initials: RP
authors.lastname: Brown
authors.affiliation: Department of Neurology, School of Medicine, University of Colorado, Aurora, CO(‡).
authors.forename: Shanae
authors.initials: S
authors.lastname: Aerts
authors.affiliation: Department of Physical Medicine and Rehabilitation, Program in Physical Therapy, School of Medicine, University of Colorado, Aurora, CO(§).
authors.forename: Margaret
authors.initials: M
authors.lastname: Schenkman
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology / Q000534:rehabilitation*; D026741:Physical Therapy Modalities