title: Increased risk of Parkinson's disease in cataract patients: a population-based cohort study.
abstract: BACKGROUND
  The purpose of this study was to investigate whether there is an association between cataracts and Parkinson's disease in Taiwan.
  
  
  METHODS
  A retrospective cohort study was conducted to analyze the database of the Taiwan National Health Insurance Program from 1999 to 2002. This study consisted of 26,031 individuals aged 40-84 years with newly diagnosed cataracts as the cataract group and 25,937 randomly selected individuals without cataracts as the non-cataract group. Both groups were matched for sex, age and index year of diagnosing cataracts. The incidence of Parkinson's disease by the end of 2011 and the association of Parkinson's disease with cataracts and other comorbidities were measured.
  
  
  RESULTS
  The overall incidence of Parkinson's disease was 1.48-fold higher in the cataract group than the non-cataract group (3.18 vs. 2.15 per 1000 person-years, crude HR 1.48, 95% CI 1.32, 1.66). After adjusting for confounding factors, the adjusted HR of Parkinson's disease was 1.26 (95% CI 1.12, 1.42) for the cataract group, when compared with the non-cataract group. Dementia (HR 2.72, 95% CI 1.92, 3.84), depression (HR 2.09, 95% CI 1.63, 2.66), hypertension (HR 1.42, 95% CI 1.26, 1.61), cerebrovascular disease (HR 1.32, 95% CI 1.07, 1.63) and age (every one year, HR 1.08, 95% CI 1.07, 1.09) were other factors significantly related to Parkinson's disease.
  
  
  CONCLUSIONS
  Overall, this study discloses a 26% increased hazard of Parkinson's disease in cataract patients. Further studies are required to investigate whether cataracts are one of non-motor manifestations of Parkinson's disease.
authors.affiliation: School of Medicine, China Medical University, Taichung, Taiwan; Department of Family Medicine, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Shih-Wei
authors.initials: SW
authors.lastname: Lai
authors.affiliation: Department of Public Health, China Medical University, Taichung, Taiwan; Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Cheng-Li
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan; Department of Internal Medicine, Taichung Tzu Chi General Hospital, Taichung, Taiwan. Electronic address: kuanfuliao@yahoo.com.tw.
authors.forename: Kuan-Fu
authors.initials: KF
authors.lastname: Liao
authors.affiliation: Department of Internal Medicine, Taichung Tzu Chi General Hospital, Taichung, Taiwan.
authors.forename: Kao-Chi
authors.initials: KC
authors.lastname: Chang-Ou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000150:complications / Q000453:epidemiology*; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data; D010300:Parkinson Disease / Q000150:complications / Q000453:epidemiology*; D013624:Taiwan / Q000453:epidemiology
keywords: Cataracts; Mitochondrial dysfunction; Parkinson's disease