title: Factors predictive of the need for levodopa therapy in early, untreated Parkinson's disease. The Parkinson Study Group.
abstract: OBJECTIVE
  To identify characteristics of patients with early, untreated Parkinson's disease that are the most important predictors of rapid functional decline.
  
  
  METHODS
  Prospective observational study of a cohort of 800 patients with early, untreated Parkinson's disease who were involved in a multicenter, randomized, double-blind, controlled clinical trial of selegiline hydrochloride (L-deprenyl) and vitamin E (alpha-tocopherol).
  
  
  METHODS
  Time from randomization to the onset of disability that necessitated levodopa therapy (end point), as judged by the enrolling investigator.
  
  
  METHODS
  Stepwise Cox regression was used in combination with clinical judgment to identify the most important independent baseline predictors of the primary end point among a host of variables, including treatment with selegiline and vitamin E, global and specific clinical measures of disease severity, demographic variables, and neuropsychological test results.
  
  
  RESULTS
  In addition to selegiline treatment and global disease severity measures, such as the stage according to the criteria of Hoehn and Yahr, impaired domestic capacity, and the activities of daily living score, the complex of postural instability/gait difficulty and bradykinesia were found to be the factors that were most highly associated with the risk of reaching the end point.
  
  
  CONCLUSIONS
  The findings suggest that patients with Parkinson's disease whose early clinical presentation includes either postural instability/gait difficulty or bradykinesia are at high risk for rapid functional decline.
authors.affiliation: Department of Biostatistics, University of Rochester Medical Center, NY 14642, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: McDermott
authors.forename: J
authors.initials: J
authors.lastname: Jankovic
authors.forename: J
authors.initials: J
authors.lastname: Carter
authors.forename: S
authors.initials: S
authors.lastname: Fahn
authors.forename: S
authors.initials: S
authors.lastname: Gauthier
authors.forename: C G
authors.initials: CG
authors.lastname: Goetz
authors.forename: L I
authors.initials: LI
authors.lastname: Golbe
authors.forename: W
authors.initials: W
authors.lastname: Koller
authors.forename: A E
authors.initials: AE
authors.lastname: Lang
authors.forename: C W
authors.initials: CW
authors.lastname: Olanow
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000188:drug therapy* / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D012642:Selegiline / Q000008:administration & dosage*; D012737:Sex Factors; D014810:Vitamin E / Q000008:administration & dosage*
chemical_list: D014810:Vitamin E; D012642:Selegiline; D007980:Levodopa