title: Reduced Risk of Parkinson Disease in Patients With Rheumatoid Arthritis: A Nationwide Population-Based Study.
abstract: OBJECTIVE
  To investigate the association between rheumatoid arthritis (RA) and the risk of developing Parkinson disease (PD).
  
  
  METHODS
  This retrospective cohort study was conducted from January 1, 1998, through December 31, 2010, using data from the Taiwan National Health Insurance Research Database. We identified 33,221 patients with newly diagnosed RA and 132,884 randomly selected age- and sex-matched patients without RA. A multivariable Cox proportional hazards regression model was used to evaluate the risk of developing PD in the RA cohort.
  
  
  RESULTS
  The multivariable Cox proportional hazards regression analysis revealed an adjusted hazard ratio of 0.65 (95% CI, 0.58-0.73) for the development of PD in the RA cohort relative to the non-RA cohort. The cumulative incidence of PD was 2.42% lower in the RA cohort than in the non-RA cohort. The risk reduction of PD development in patients affected with RA was independent of treatment with disease-modifying antirheumatic drugs (DMARDs); subgroup analysis of patients treated with biologic DMARDs revealed further risk reduction (adjusted hazard ratio, 0.57; 95% CI, 0.41-0.79).
  
  
  CONCLUSIONS
  Patients with RA have a reduced risk of developing PD. This risk reduction was independent of treatment with DMARDs; however, biologic DMARDs appear to further reduce this risk. Further research is necessary to explore the underlying mechanism.
authors.affiliation: Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yueh-Feng
authors.initials: YF
authors.lastname: Sung
authors.affiliation: Rheumatology/Immunology and Allergy, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Feng-Cheng
authors.initials: FC
authors.lastname: Liu
authors.affiliation: Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chun-Chieh
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Jiunn-Tay
authors.initials: JT
authors.lastname: Lee
authors.affiliation: Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Fu-Chi
authors.initials: FC
authors.lastname: Yang
authors.affiliation: School of Public Health, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Chou
authors.affiliation: School of Medicine, Graduate Institute of Clinical Medical Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan; Department of Nuclear Medicine and PET Center, China Medical University, Taichung, Taiwan; Department of Bioinformatics and Medical Engineering, Asia 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: Department of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Clinical Medicine Science and School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Kao
authors.affiliation: Graduate Institute of Chinese Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Lo
authors.affiliation: Molecular and Genomic Epidemiology Center, and Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, Taiwan. Electronic address: yang_t_y@yahoo.com.tw.
authors.forename: Tse-Yen
authors.initials: TY
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012042:Registries; D012189:Retrospective Studies; D012306:Risk; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents