title: Predictors of Functional Decline in Early Parkinson's Disease: NET-PD LS1 Cohort.
abstract: BACKGROUND
  Data on predictors of decline in PD are largely based on de-novo populations and limited to the use of motor outcomes that fail to capture the full scope of disease.
  
  
  OBJECTIVE
  Determine the clinical predictors of decline in early treated PD using a novel multi-domain measure.
  
  
  METHODS
  Data from NINDS Exploratory Trials in PD Long-Term Study 1 (NET-PD LS1), a multicenter Phase 3 study of creatine in early treated PD, were analyzed. Functional decline was defined by a global outcome metric (GO) that consisted of: Schwab and England ADL scale, PD 39-item Questionnaire, Unified PD Rating Scale, Ambulatory Capacity Score, Symbol Digit Modalities Test, and Modified Rankin Scale. Univariate and multivariate models were used to test the association of predictors of interest with a standardized rank-sum of the GO.
  
  
  RESULTS
  765 of 1741 participants completed five-year assessments and were included. Older age at disease onset (p <  0.0001), higher baseline levodopa equivalent dose (p = 0.01), and worse Scales for Outcomes of Parkinson's Disease Cognition score (p = 0.001) at baseline were the strongest predictors of functional decline in multivariate analysis. PD symptom subtype was not a significant predictor of outcome (p = 0.42). The full model was only a modest predictor of change in GO (R2 = 0.186).
  
  
  CONCLUSIONS
  This is the largest study to systematically assess predictors of functional decline in early treated PD over several years, and the first to use a multi-domain outcome measure of decline. Older age at disease onset and worse cognition, and not PD subtype, were predictors of decline.
authors.affiliation: Northwestern University, Chicago, IL, USA.
authors.forename: Danny
authors.initials: D
authors.lastname: Bega
authors.affiliation: University of Texas Health Science Center, Houston, TX, USA.
authors.forename: Soeun
authors.initials: S
authors.lastname: Kim
authors.affiliation: University of Texas Health Science Center, Houston, TX, USA.
authors.forename: Yunxi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Jordan
authors.initials: J
authors.lastname: Elm
authors.affiliation: Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Schneider
authors.affiliation: University of South Florida, Tampa, FL, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Hauser
authors.affiliation: Oregon Health Sciences University, Portland, OR, USA.
authors.forename: Andy
authors.initials: A
authors.lastname: Fraser
authors.affiliation: Northwestern University, Chicago, IL, USA.
authors.forename: Tanya
authors.initials: T
authors.lastname: Simuni
mesh_terms: D000203:Activities of Daily Living; D017668:Age of Onset; D000368:Aged; D000978:Antiparkinson Agents / Q000008:administration & dosage*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D055825:National Institute of Neurological Disorders and Stroke (U.S.); D017063:Outcome Assessment, Health Care / Q000379:methods*; D010300:Parkinson Disease / Q000175:diagnosis* / Q000188:drug therapy; D011379:Prognosis; D012720:Severity of Illness Index; D014481:United States
chemical_list: D000978:Antiparkinson Agents
keywords: NET-PD; Parkinson’s disease