title: Risk of stroke in patients with idiopathic Parkinson disease.
abstract: OBJECTIVE
  Large population based studies on the association of Parkinson disease (PD) with stroke are scarce. This study aimed to quantify the risk of a first-time diagnosis of idiopathic PD in patients with a history of stroke, and to assess incidence rates for stroke in PD patients.
  
  
  METHODS
  We used the UK-based General Practice Research Database to compare the prevalence of stroke/TIA in newly diagnosed PD patients and in a matched comparison group without PD between 1994 and 2005. We conducted a follow-up study with a nested case-control analysis to quantify the risk of incident stroke/TIA in relation to a previous PD diagnosis.
  
  
  RESULTS
  A history of stroke/TIA was associated with a significantly increased relative risk of being diagnosed with PD compared to patients without such a history (adj. odds ratio [OR] 1.65, 95% confidence intervals [CI] 1.47-2.00). In the cohort study, the crude incidence rate ratios (IRRs) for incident hemorrhagic stroke, ischemic stroke or TIA were 0.66 (95% CI 0.26-1.72), 1.46 (95% CI 1.03-2.07) and 1.86 (95% CI 1.40-2.47), respectively.
  
  
  CONCLUSIONS
  In this large observational study the risk of a PD diagnosis was significantly increased after a previous stroke event, as was the risk of a first-time ischemic stroke in newly diagnosed PD patients compared to persons free of PD.
authors.affiliation: Basel Pharmacoepidemiology Unit, Division of Clinical Pharmacology and Toxicology, University Hospital Basel, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Becker
authors.forename: Susan S
authors.initials: SS
authors.lastname: Jick
authors.forename: Christoph R
authors.initials: CR
authors.lastname: Meier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016001:Confidence Intervals; D016208:Databases, Factual / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010300:Parkinson Disease / Q000150:complications* / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology