title: Risk of developing Parkinson's disease among patients with asthma: a nationwide longitudinal study.
abstract: BACKGROUND
  A cross-sectional retrospective study suggested a link between allergic diseases and Parkinson's disease. However, the temporal association between asthma and Parkinson's disease remains unknown.
  
  
  METHODS
  From the Taiwan National Health Insurance Research Database, 10 455 patients who were diagnosed with asthma between 1998 and 2008 and aged ≥45 years and 41 820 age- and sex-matched controls were selected for our study and observed until the end of 2011. Those who developed Parkinson's disease during the follow-up period were identified. We also examined the asthma severity, as indicated by the frequency of admission (times per year) for asthma exacerbation, and the risk of subsequent Parkinson's disease.
  
  
  RESULTS
  Patients with asthma had an increased risk of developing Parkinson's disease (hazard ratio [HR]: 3.10, 95% confidence interval [CI]: 2.20-4.36) after we adjusted for demographic data, health system use, medical comorbidities, and medication use. Sensitivity tests yielded consistent findings after we excluded observations on the first year (HR: 2.90, 95% CI: 2.04-4.13) and first 3 years (HR: 2.46, 95% CI: 1.64-3.69). Patients with asthma who had more frequent admissions (times per year) during the follow-up period exhibited a greater risk of subsequent Parkinson's disease (>2: HR: 16.42, 95% CI: 5.88-45.91; 1-2: 12.69, 95% CI: 5.03-31.71; 0-1: HR: 2.92, 95% CI: 1.91-4.49).
  
  
  CONCLUSIONS
  Patients with asthma had an elevated risk of developing Parkinson's disease later in life, and we observed a dose-dependent relationship between greater asthma severity and a higher risk of subsequent Parkinson's disease.
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.
authors: C-M
authors: CM
authors: Cheng
authors: Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan.|Center for Geriatrics and Gerontology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors: Y-H
authors: YH
authors: Wu
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: S-J
authors: SJ
authors: Tsai
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: Y-M
authors: YM
authors: Bai
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: J-W
authors: JW
authors: Hsu
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: K-L
authors: KL
authors: Huang
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: T-P
authors: TP
authors: Su
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: C-T
authors: CT
authors: Li
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: C-F
authors: CF
authors: Tsai
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: A C
authors: AC
authors: Yang
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: W-C
authors: WC
authors: Lin
authors: School of Traditional Chinese Medicine, Chang Gung University, Taoyuan, Taiwan.|Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan.|Division of Hepatology, Department of Gastroenterology and Hepatology, Liver Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors: T-L
authors: TL
authors: Pan
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.
authors: W-H
authors: WH
authors: Chang
authors: Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Institute of Hospital and Health Care Administration, National Yang-Ming University, Taipei, Taiwan.
authors: T-J
authors: TJ
authors: Chen
authors: Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan.|Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors: M-H
authors: MH
authors: Chen
mesh_terms: D000368:Aged; D001249:Asthma / Q000453:epidemiology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Parkinson's disease; allergic diseases; asthma; severity of asthma