title: Natural history and effectiveness of early detection of Parkinson's disease: results from two community-based programmes in Taiwan (KCIS no. 11).
abstract: OBJECTIVE
  The natural course of Parkinson's disease (PD), as measured on the Hoehn-Yahr (H-Y) scale, and the impact that early detection would have on prognosis for those with the disease, has barely been addressed since the introduction of L-dopa. This study aimed to elucidate the natural history of PD and effectiveness of early detection in reducing advanced disability and mortality.
  
  
  METHODS
  A total of 21 362 participants aged 40 years or older were invited to two community-based programmes for the early detection of PD. The step-by-step annual progression rates from H-Y stage I to stage IV or V, and cumulative survival rates, by the H-Y scale, were estimated and applied to simulated data to assess the impact of different screening intervals upon stage at diagnosis and subsequent survival.
  
  
  RESULTS
  The average duration in stages I, II and III was estimated as 2.83, 6.62 and 1.41 years, respectively. The average delay time before deteriorating into H-Y stage III was 9.45 year. Application of these parameters to simulated model predicted a 36% (95% CI: 28-39%), 26% (95% CI: 20-32%) and 19% (95% CI: 13-24%) reduction in death for annual, 5-yearly and 10-yearly screening programmes, respectively.
  
  
  CONCLUSIONS
  The present study recommended a 5-yearly screening programme, with 74% of PD cases prevented from progressing to H-Y stage III or worse within 10 years of diagnosis, and leading to a corresponding 26% reduction in mortality.
authors.affiliation: Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Horng-Huei
authors.initials: HH
authors.lastname: Liou
authors.forename: Chia-Yun
authors.initials: CY
authors.lastname: Wu
authors.forename: Yueh-Hsia
authors.initials: YH
authors.lastname: Chiu
authors.forename: Amy Ming-Fang
authors.initials: AM
authors.lastname: Yen
authors.forename: Rong-Chi
authors.initials: RC
authors.lastname: Chen
authors.forename: Ta-Fu
authors.initials: TF
authors.lastname: Chen
authors.forename: Chih-Chuan
authors.initials: CC
authors.lastname: Chen
authors.forename: Yuarn-Chung
authors.initials: YC
authors.lastname: Hwang
authors.forename: Ying-Rong
authors.initials: YR
authors.lastname: Wen
authors.forename: Tony Hsiu-Hsi
authors.initials: TH
authors.lastname: Chen
mesh_terms: D000328:Adult; D003153:Community Health Services; D003198:Computer Simulation; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology; D015397:Program Evaluation; D013223:Statistics as Topic; D013624:Taiwan