title: Automated gait and balance parameters diagnose and correlate with severity in Parkinson disease.
abstract: OBJECTIVE
  To assess the suitability of instrumented gait and balance measures for diagnosis and estimation of disease severity in PD.
  
  
  METHODS
  Each subject performed iTUG (instrumented Timed-Up-and-Go) and iSway (instrumented Sway) using the APDM(®) Mobility Lab. MDS-UPDRS parts II and III, a postural instability and gait disorder (PIGD) score, the mobility subscale of the PDQ-39, and Hoehn & Yahr stage were measured in the PD cohort. Two sets of gait and balance variables were defined by high correlation with diagnosis or disease severity and were evaluated using multiple linear and logistic regressions, ROC analyses, and t-tests.
  
  
  RESULTS
  135 PD subjects and 66 age-matched controls were evaluated in this prospective cohort study. We found that both iTUG and iSway variables differentiated PD subjects from controls (area under the ROC curve was 0.82 and 0.75 respectively) and correlated with all PD severity measures (R(2) ranging from 0.18 to 0.61). Objective exam-based scores correlated more strongly with iTUG than iSway. The chosen set of iTUG variables was abnormal in very mild disease. Age and gender influenced gait and balance parameters and were therefore controlled in all analyses.
  
  
  CONCLUSIONS
  Our study identified sets of iTUG and iSway variables which correlate with PD severity measures and differentiate PD subjects from controls. These gait and balance measures could potentially serve as markers of PD progression and are under evaluation for this purpose in the ongoing NIH Parkinson Disease Biomarker Program.
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center, United States.
authors.forename: D Campbell
authors.initials: DC
authors.lastname: Dewey
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center, United States.
authors.forename: Svjetlana
authors.initials: S
authors.lastname: Miocinovic
authors.affiliation: Department of Clinical Sciences, University of Texas Southwestern Medical Center, United States.
authors.forename: Ira
authors.initials: I
authors.lastname: Bernstein
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center, United States.
authors.forename: Pravin
authors.initials: P
authors.lastname: Khemani
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center, United States.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Dewey
authors.affiliation: Department of Physical Therapy, University of Texas Southwestern Medical Center, United States.
authors.forename: Ross
authors.initials: R
authors.lastname: Querry
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center, United States.
authors.forename: Shilpa
authors.initials: S
authors.lastname: Chitnis
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center, United States. Electronic address: Richard.dewey@utsouthwestern.edu.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Dewey
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D003936:Diagnosis, Computer-Assisted; D005260:Female; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000175:diagnosis; D004856:Postural Balance / Q000502:physiology*; D011594:Psychometrics; D012372:ROC Curve; D012042:Registries; D012189:Retrospective Studies; D012678:Sensation Disorders / Q000175:diagnosis* / Q000209:etiology*; D011795:Surveys and Questionnaires
keywords: Balance; Diagnosis; Gait; Mobility Lab; Parkinson; Severity
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