title: Time trends in the prevalence and incidence of Parkinson's disease in Taiwan: A nationwide, population-based study.
abstract: OBJECTIVE
  Identifying trends in the prevalence and incidence of Parkinson's disease (PD) may yield information that supports public health goals. Our aim was to evaluate time-trend changes in the prevalence and incidence of PD in Taiwan between 2004 and 2011.
  
  
  METHODS
  This retrospective, nationwide, longitudinal study used the Taiwan National Health Insurance Research Database to identify patients with PD from 2004 to 2011 based on having ICD-9-CM diagnostic codes, which were assigned by neurologists, and being prescribed PD medication. Annual incidence and prevalence were calculated, and time-trend analyses were estimated assuming a Poisson distribution.
  
  
  RESULTS
  Over the study period, 19,302 patients in 2004 and 41,606 patients in 2011 fulfilling the study criteria for PD were included in the analysis. The average age-standardized prevalence of PD per 100,000 of population was 84.8 in 2004 and 147.7 in 2011, with a 7.9% yearly increase. Increasing prevalence trends of PD were statistically significant (p < 0.001) in all age groups, with the steepest rate among those aged ≥ 80 years. In contrast, the average age-standardized incidence of PD decreased steadily from 35.3 per 100,000 in 2005 to 28.8 per 100,000 in 2011. The incidence rate was higher in men than in women, and increased with age.
  
  
  CONCLUSIONS
  We identified an increasing trend in the annual prevalence rates of PD from 2004 to 2011; however, the substantial decline in the incidence of PD suggests that some major environmental risk factors for PD were removed from this population during this time period.
authors.affiliation: Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Weng-Ming
authors.initials: WM
authors.lastname: Liu
authors.affiliation: Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Ruey-Meei
authors.initials: RM
authors.lastname: Wu
authors.affiliation: Department of Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan; Cardiovascular Center, National Taiwan University Hospital Yun-Lin Branch, Dou-Liou City, Yun-Lin County, Taiwan.
authors.forename: Jou-Wei
authors.initials: JW
authors.lastname: Lin
authors.affiliation: Institute of Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Liu
authors.affiliation: Department of Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan. Electronic address: chiahsuin123@yahoo.com.tw.
authors.forename: Chia-Hsuin
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: chlin@ntu.edu.tw.
authors.forename: Chin-Hsien
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D016208:Databases, Factual; D005260:Female; D006801:Humans; D015994:Incidence; D038801:International Classification of Diseases; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009313:National Health Programs; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology*; D015995:Prevalence; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors
keywords: Parkinson's disease; incidence; population study; prevalence; time trend