Review: In adults with diabetes, aspirin does not prevent CV events compared with placebo
A review published prior to the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes trial found that aspirin only reduced cardiovascular events in diabetes patients with pre-existing cardiovascular disease.
Aspirin was overall associated with reduced cardiovascular events in patients with diabetes, according to a recent review, but the effect appeared to be isolated to patients with pre-existing cardiovascular disease (CVD). The authors concluded that guidelines encouraging the use of aspirin for primary prevention of CVD in patients with diabetes are not supported by current evidence. The review included 10 randomized controlled trials (RCTs) comparing aspirin to placebo or no treatment, and it was published prior to the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes trial.
The study was published by Diabetic Medicine on May 22. The following commentary by Harvey J. Murff, MD, MPH, was published in the ACP Journal Club section of the Nov. 15 Annals of Internal Medicine.
Aspirin has been recommended for primary prevention of CVD based on RCTs that showed reduced risk for nonfatal [myocardial infarction]. The effect of aspirin on CVD is modest, and the decision to initiate aspirin therapy should be individualized to optimize overall benefit. Diabetes is a risk factor for CVD, so aspirin might be effective in preventing CVD in patients with diabetes. However, the updated meta-analysis by Kunutsor and colleagues confirms earlier reviews indicating that the effects of aspirin are, at best, limited in reducing the risk for overall CVD in diabetes patients without known CVD.
Aspirin for primary prevention of CVD in patients without diabetes has the most favorable benefit-to-risk ratio in patients with increased risk for CVD and lower risk for gastrointestinal complications. Subgroup analyses by Kunutsor and colleagues suggested that patients with lower risk for CVD might derive greater benefit from aspirin than patients with higher risk for CVD, but the difference was not statistically significant. This conclusion is counter to most recommendations and, as a secondary analysis, should be cautiously interpreted. Currently, the largest clinical trial with targeted enrollment of patients with diabetes (n >15,000) is ongoing and might clarify the benefits and risks of aspirin therapy for primary CVD prevention and which subgroups benefit most.
Given the current lack of conclusive evidence supporting the use of aspirin for primary prevention of CVD in patients with diabetes, how can clinicians best minimize CVD risks? With the notable exception of lipid-lowering therapy, most clinical trials have not shown a benefit of lifestyle interventions, weight loss, or blood pressure control on primary CVD prevention in patients with diabetes. Nevertheless, these interventions can be justified due to their beneficial effects on glycemic control and microvascular disease along with an exceptional safety profile.