title: Natural History of Parkinson's Disease in the Province of Segovia: Disability in a 20 Years Longitudinal Study.
abstract: BACKGROUND
  Parkinson's disease mainly affects the elderly population causing a progressive functional disability with motor, psychic, and cognitive deterioration.
  
  
  OBJECTIVE
  This study was carried out to evaluate disability caused by Parkinson's disease by analyzing the median time to reach Hoehn and Yahr stage III and to investigate predictor variables based on a 20-year longitudinal follow-up study.
  
  
  METHODS
  We examined 273 patients with Parkinson's disease recruited between 1978 and 1998. We performed a survival analysis using the Kaplan-Meier method to determine the time to disability and we used a Cox regression model to adjust prognosis factors.
  
  
  RESULTS
  The median time to reach Hoehn and Yahr stage III was 7.73 years (95% CI: 5.95-8.05). Independent predictors of disability were: age at onset, the hazard ratio (HR) = 1.10, 95% CI: 1.08-1.12; UPDRS II (activities of daily living) HR = 1.08, 95% CI: 1.03-1.14; and akinesia and rigidity at onset HR = 1.55, 95% CI: 1.07-2.24.
  
  
  CONCLUSIONS
  Patients with Parkinson's disease evolve gradually toward disability, and prognostic factors of this evolution were identified.
authors.affiliation: Division of Neurology, General Hospital of Segovia, Segovia, Spain.
authors.forename: Jacinto
authors.initials: J
authors.lastname: Duarte
authors.forename: Luis Miguel
authors.initials: LM
authors.lastname: García Olmos
authors.forename: Amelia
authors.initials: A
authors.lastname: Mendoza
authors.forename: Ángel
authors.initials: Á
authors.lastname: Martínez Pueyo
authors.forename: Luis Erik
authors.initials: LE
authors.lastname: Clavería
mesh_terms: D000368:Aged; D004185:Disability Evaluation; D006233:Persons with Disabilities; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology* / Q000503:physiopathology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology