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Aspirin “resistance” and risk of cardiovascular morbidity: systematic review and meta-analysis

BMJ 2008; 336 doi: (Published 24 January 2008) Cite this as: BMJ 2008;336:195
  1. George Krasopoulos, cardiovascular surgery fellow1,
  2. Stephanie J Brister, associate professor1,
  3. W Scott Beattie, R Fraser Elliot chair in cardiac anaesthesia2,
  4. Michael R Buchanan, professor3
  1. 1University Health Network, Division of Cardiovascular Surgery, Toronto General Hospital
  2. 2University Health Network, Department of Anaesthesiology, Toronto General Hospital
  3. 3McMaster University, Department of Pathology and Molecular Medicine, Hamilton, ON, Canada L8S 4L8
  1. Correspondence to: M R Buchanan mbuchan{at}
  • Accepted 6 November 2007


Objective To determine if there is a relation between aspirin “resistance” and clinical outcomes in patients with cardiovascular disease.

Design Systematic review and meta-analysis.

Data source Electronic literature search without language restrictions of four databases and hand search of bibliographies for other relevant articles.

Review methods Inclusion criteria included a test for platelet responsiveness and clinical outcomes. Aspirin resistance was assessed, using a variety of platelet function assays.

Results 20 studies totalling 2930 patients with cardiovascular disease were identified. Most studies used aspirin regimens, ranging from 75-325 mg daily, and six studies included adjunct antiplatelet therapy. Compliance was confirmed directly in 14 studies and by telephone or interviews in three. Information was insufficient to assess compliance in three studies. Overall, 810 patients (28%) were classified as aspirin resistant. A cardiovascular related event occurred in 41% of patients (odds ratio 3.85, 95% confidence interval 3.08 to 4.80), death in 5.7% (5.99, 2.28 to 15.72), and an acute coronary syndrome in 39.4% (4.06, 2.96 to 5.56). Aspirin resistant patients did not benefit from other antiplatelet treatment.

Conclusion Patients who are resistant to aspirin are at a greater risk of clinically important cardiovascular morbidity long term than patients who are sensitive to aspirin.


  • We thank M Dang and M Kirchhoff-Dobias for translating the Chinese and Czech papers. This study was supported by discretionary funds of SJB and MRB. The following authors verified our data interpretations: K Andersen (Norway); J Berrouschot, K-H Grotemeyer, and H Topka (Germany); W-H Chen (China); G Hobikoǒlu and MB Yilmaz (Turkey); and R Poston (United States).

  • Contributors: All authors did the literature search; reviewed the abstracts, papers, and data; and reviewed the manuscript and made appropriate amendments. MRB wrote the paper. All authors are guarantors for the paper.

  • Funding: None.

  • Competing interests: None declared.

  • Ethical approval: Not required.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Accepted 6 November 2007
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