title: Comparison of antiplatelet regimens in secondary stroke prevention: a nationwide cohort study.
abstract: BACKGROUND
  In patients with ischemic stroke of non-cardioembolic origin, acetylsalicylic acid, clopidogrel, or a combination of acetylsalicylic acid and dipyridamole are recommended for the prevention of a recurrent stroke. The purpose of this study was to examine the risk of bleeding or recurrent stroke associated with these three treatments.
  
  
  METHODS
  Patients who were discharged with first-time ischemic stroke from 2007-2010, with no history of atrial fibrillation were identified from Danish nationwide registries. Hazard ratios (HRs) and 1-year risks of recurrent ischemic stroke and bleeding were calculated for each antiplatelet regimen.
  
  
  RESULTS
  Among patients discharged after first-time ischemic stroke, 3043 patients were treated with acetylsalicylic acid, 12,295 with a combination of acetylsalicylic acid and dipyridamole, and 3885 with clopidogrel. Adjusted HRs for clopidogrel versus the combination of acetylsalicylic acid and dipyridamole were 1.02 (95% confidence interval [CI]: 0.89-1.17) for ischemic stroke and 1.06 (95% CI: 0.83-1.35) for bleeding. Adjusted HRs for acetylsalicylic acid versus the combination of acetylsalicylic acid and dipyridamole were 1.48 (95% CI: 1.31-1.67) for stroke and 1.47 (95% CI: 1.18-1.82) for bleeding. Clopidogrel versus acetylsalicylic acid yielded HRs of 0.69 (95% CI: 0.59-0.81) and 0.72 (95% CI: 0.55-0.96) for stroke and bleeding, respectively. The 1-year predicted risks associated with acetylsalicylic acid, the combination of acetylsalicylic acid and dipyridamole, and clopidogrel were 11.1 (95% CI: 10.2-12.2), 7.7 (95% CI: 7.3-8.3), and 8.0 (95% CI: 6.9-8.7) for ischemic stroke, respectively; while, the risks for bleeding were 3.4 (95% CI: 2.8-3.9), 2.4 (95% CI: 2.1-2.7), and 2.4 (95% CI: 1.9-2.9), respectively.
  
  
  CONCLUSIONS
  Clopidogrel and the combination of acetylsalicylic acid and dipyridamole were associated with similar risks for recurrent ischemic stroke and bleeding; whereas acetylsalicylic acid was associated with higher risks for both ischemic stroke and bleeding. The latter finding may partially be explained by selection bias.
authors.affiliation: Aalborg University Hospital, Forskningens Hus, Sdr. Skovvej 15, 9000, Aalborg, Denmark. christinebenn@hotmail.com.|Department of Cardiology, Gentofte Hospital, Gentofte, Denmark. christinebenn@hotmail.com.
authors.forename: Christine Benn
authors.initials: CB
authors.lastname: Christiansen
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.
authors.forename: Jannik
authors.initials: J
authors.lastname: Pallisgaard
authors.affiliation: Department of Public Health, Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Thomas Alexander
authors.initials: TA
authors.lastname: Gerds
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.
authors.forename: Jonas Bjerring
authors.initials: JB
authors.lastname: Olesen
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.
authors.forename: Mads Emil
authors.initials: ME
authors.lastname: Jørgensen
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.
authors.forename: Anna Karin
authors.initials: AK
authors.lastname: Numé
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Carlson
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.
authors.forename: Søren Lund
authors.initials: SL
authors.lastname: Kristensen
authors.affiliation: Department of Cardiology, Gentofte Hospital, Gentofte, Denmark.|National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Gislason
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000009:adverse effects*; D002545:Brain Ischemia / Q000188:drug therapy / Q000453:epidemiology; D002543:Cerebral Hemorrhage / Q000139:chemically induced* / Q000453:epidemiology; D000077144:Clopidogrel; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D004176:Dipyridamole / Q000009:adverse effects*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D012008:Recurrence; D012042:Registries; D055502:Secondary Prevention; D020521:Stroke / Q000453:epidemiology / Q000517:prevention & control*; D013988:Ticlopidine / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D010975:Platelet Aggregation Inhibitors; D004176:Dipyridamole; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin