In diabetes, aspirin may prevent major cardiovascular events

Red blood cells

Aspirin is widely used to prevent cardiovascular events in people with a history of cardiovascular disease (CVD).

Many people believe that it may also prevent CVD in people who have no previous history of CVD, so-called “primary prevention”.  However, the evidence is unclear.

As diabetes is an important risk factor for CVD, a systematic review was carried out to assess the effectiveness of aspirin for primary prevention of CVD in people with diabetes.

Bottom line

In people with diabetes without previous cardiovascular disease, aspirin may prevent major cardiovascular events.  However, it may also cause bleeding and gastrointestinal problems.

About the review

  • Patients:  Diabetes, no previous cardiovascular disease
  • Intervention: Aspirin  (variable dosage)
  • Outcome:  Composite outcome of any major adverse cardiovascular event (MACE:  including myocardial infarction, stroke and cardiovascular death).
  • Study type:  Systematic review of randomised trials, comprising 11,618 patients.

Appraisal tips

Readers of this review are advised to consider the following:

  • The reviewers report that there was no significant statistical heterogeneity between the studies.  However, we would advise readers to consider how possible effects may vary among sub-groups of patients according to type or duration of diabetes, glycemic control, patient age and other risk factors for cardiovascular disease.
  • The reviewers did not find evidence that the dosage of aspirin influenced the amount of benefit.  The individual studies used a wide range of doses.
  • The composite outcome for MACE was only marginally statistically significant. The relative risk was 0.91 (95% confidence intervals, CI, 0.82-1.00).  It is possible that this result could have been seen even if there was no difference between aspirin and placebo.  More data is needed to further specify the benefits.
  • The broad range of confidence intervals, in spite of the large number of individual patients, shows that the outcome event rates were low.  This further indicates the need for more research and continued follow-up of the patients in these trials.

Reference

Butalia S, Leung AA, Ghali WA, Rabi DM.  Aspirin effect on the incidence of major adverse cardiovascular events in patients with diabetes mellitus: a systematic review and meta-analysis.  Cardiovasc Diabetol. 2011; 10: 25.

Full text is available online from the link above.