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Aspirin for primary prevention of cardiovascular events in people with diabetes: meta-analysis of randomised controlled trials

BMJ 2009; 339 doi: (Published 06 November 2009) Cite this as: BMJ 2009;339:b4531
  1. Giorgia De Berardis, research officer1,
  2. Michele Sacco, research officer1,
  3. Giovanni F M Strippoli, editor and regional coordinator of the Cochrane Renal Group12,
  4. Fabio Pellegrini, senior biostatistician1,
  5. Giusi Graziano, biostatistician1,
  6. Gianni Tognoni, institute director3,
  7. Antonio Nicolucci, department head1
  1. 1Department of Clinical Pharmacology and Epidemiology, Consorzio Mario Negri Sud, Via Nazionale 8/a, 66030 S. Maria Imbaro, Italy
  2. 2Diaverum Medical Scientific Office, Lund, Sweden, School of Public Health, University of Sydney, Australia, and Cochrane Renal Group, Sydney, Australia
  3. 3Consorzio Mario Negri Sud, S Maria Imbaro, Italy
  1. Correspondence to: A Nicolucci nicolucci{at}
  • Accepted 9 September 2009


Objective To evaluate the benefits and harms of low dose aspirin in people with diabetes and no cardiovascular disease.

Design Meta-analysis of randomised controlled trials.

Data sources Medline (1966-November 2008), the Cochrane central register of controlled trials (Cochrane Library 2008;issue 4), and reference lists of retrieved articles.

Review methods Randomised trials of aspirin compared with placebo or no aspirin in people with diabetes and no pre-existing cardiovascular disease were eligible for inclusion. Data on major cardiovascular events (death from cardiovascular causes, non-fatal myocardial infarction, non-fatal stroke, and all cause mortality) were extracted and pooled with a random effect model. Results are reported as relative risks with 95% confidence intervals.

Results Of 157 studies in the literature searches, six were eligible (10 117 participants). When aspirin was compared with placebo there was no statistically significant reduction in the risk of major cardiovascular events (five studies, 9584 participants; relative risk 0.90, 95% confidence interval 0.81 to 1.00), cardiovascular mortality (four studies, n=8557, 0.94; 0.72 to 1.23), or all cause mortality (four studies, n=8557; 0.93, 0.82 to 1.05). Significant heterogeneity was found in the analysis for myocardial infarction (I2=62.2%; P=0.02) and stroke (I2=52.5%; P=0.08). Aspirin significantly reduced the risk of myocardial infarction in men (0.57, 0.34 to 0.94) but not in women (1.08, 0.71 to 1.65; P for interaction=0.056). Evidence relating to harms was inconsistent.

Conclusions A clear benefit of aspirin in the primary prevention of major cardiovascular events in people with diabetes remains unproved. Sex may be an important effect modifier. Toxicity is to be explored further.


  • Contributors: AN was involved in the concept and design of the review, analysis and interpretation of data, and writing the final manuscript. GDB and MS were equally involved in the quality assessment of studies, data extraction, and writing of the manuscript. FP and GG were involved in data analysis. GS was involved in critical revision for intellectual content and interpretation of data and assisted with writing the final manuscript. GT gave critical revision of the manuscript for important intellectual content. All authors approved the manuscript for publication. AN is the guarantor. All authors had full access to all of the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.

  • Funding: None.

  • Competing interests: None declared.

  • Ethical approval: Not required.

  • Data sharing: No additional data available.

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