title: Is clopidogrel better than aspirin following breakthrough strokes while on aspirin? A retrospective cohort study.
abstract: OBJECTIVE
  There is insufficient evidence on which to base a recommendation for optimal antiplatelet therapy following a stroke while on aspirin. The objective was to compare clopidogrel initiation vs aspirin reinitiation for vascular risk reduction among patients with ischaemic stroke on aspirin at the time of their index stroke.
  
  
  METHODS
  Retrospective.
  
  
  METHODS
  We conducted a nationwide cohort study by retrieving all hospitalised patients (≥18 years) with a primary diagnosis of ischaemic stroke between 2003 and 2009 from Taiwan National Health Insurance Research Database.
  
  
  METHODS
  Among 3862 patients receiving aspirin before the index ischaemic stroke and receiving either aspirin or clopidogrel after index stroke during follow-up period, 1623 were excluded due to a medication possession ratio <80%. Also, 355 were excluded due to history of atrial fibrillation, valvular heart disease or coagulopathy. Therefore, 1884 patients were included in our final analysis.
  
  
  METHODS
  Patients were categorised into two groups based on whether clopidogrel or aspirin was prescribed during the follow-up period. Follow-up was from time of the index stroke to admission for recurrent stroke or myocardial infarction, death or the end of 2010.
  
  
  METHODS
  The primary end point was hospitalisation due to a new-onset major adverse cardiovascular event (MACE: composite of any stroke or myocardial infarction). The leading secondary end point was any recurrent stroke.
  
  
  RESULTS
  Compared to aspirin, clopidogrel was associated with a lower occurrence of future MACE (HR=0.54, 95% CI 0.43 to 0.68, p<0.001, number needed to treat: 8) and recurrent stroke (HR=0.54, 95% CI 0.42 to 0.69, p<0.001, number needed to treat: 9) after adjustment of relevant covariates.
  
  
  CONCLUSIONS
  Among patients with an ischaemic stroke while taking aspirin, clopidogrel initiation was associated with fewer recurrent vascular events than aspirin reinitiation.
authors.affiliation: Department of Neurology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Chiayi Branch, Puzi, Taiwan.
authors.forename: Meng
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department of Neurology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Chiayi Branch, Puzi, Taiwan.
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Wu
authors.affiliation: Department of Neurology, Stroke Center, Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Saver
authors.affiliation: Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Hsuei-Chen
authors.initials: HC
authors.lastname: Lee
authors.affiliation: Department of Neurology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Chiayi Branch, Puzi, Taiwan.
authors.forename: Jiann-Der
authors.initials: JD
authors.lastname: Lee
authors.affiliation: Department of Neurology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Kaohsiung Branch, Kaohsiung, Taiwan.
authors.forename: Ku-Chou
authors.initials: KC
authors.lastname: Chang
authors.affiliation: Department of Neurology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Chiayi Branch, Puzi, Taiwan.
authors.forename: Chih-Ying
authors.initials: CY
authors.lastname: Wu
authors.affiliation: Department of Neurology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Linkou Branch, Taoyuan, Taiwan.
authors.forename: Tsong-Hai
authors.initials: TH
authors.lastname: Lee
authors.affiliation: Department of Healthcare Management, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Hui-Hsuan
authors.initials: HH
authors.lastname: Wang
authors.affiliation: Department of Neurology, Stroke Center, Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: Neal M
authors.initials: NM
authors.lastname: Rao
authors.affiliation: Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Ovbiagele
mesh_terms: D000368:Aged; D001241:Aspirin / Q000627:therapeutic use*; D002545:Brain Ischemia / Q000453:epidemiology / Q000517:prevention & control*; D000077144:Clopidogrel; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000639:trends; D006801:Humans; D015994:Incidence; D008297:Male; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D012008:Recurrence; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013624:Taiwan / Q000453:epidemiology; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin
keywords: CLINICAL PHARMACOLOGY; EPIDEMIOLOGY