Clinical Question

Is low-dose aspirin effective for the primary prevention of cardiovascular disease in moderate-risk patients?

Bottom Line

In this study, after five years of treatment, patients at a moderate risk of heart disease who took low-dose aspirin did not show a decrease in coronary events and all-cause mortality and had slightly more gastrointestinal bleeding. If you are confused by all the aspirin-related folderol of late, join the club. Using aspirin for primary prevention of cardiovascular disease is not a one-size-fits-all proposition. We need to risk-stratify patients according to benefits and harms and engage in shared decision-making with each patient. (Level of Evidence = 1b)

Synopsis

Low-dose aspirin for secondary prevention and in the face of acute coronary events is pretty much a slam dunk. Despite years of research, several meta-analyses, and numerous guidelines, its use for primary prevention still seems to be controversial. The researchers point out that most of the recommendations are largely for patients whose 10-year risk of a coronary event exceeds 20% and the role of aspirin in patients of intermediate risk is less clear. They conducted a double-blind randomized trial of aspirin, 100 mg daily (n = 6,270), or placebo (n = 6,276) in patients at a moderate risk of coronary artery disease. The study participants were men at least 55 years of age or women at least 60 years of age with a 10% to 20% 10-year risk based on age, sex, smoking status, blood pressure, lipid concentrations, and family history. They excluded patients with diabetes mellitus and those at high risk for bleeding complications. Using intention-to-treat analysis, after five years the rate of events (a composite of myocardial infarction, stroke, cardiovascular death, unstable angina, or transient ischemic attack) was similar between the treatment groups (4.3% vs. 4.5%, respectively). The overall death rate was the same (2.6%) in each group. The aspirin-treated patients had more bleeding events (1% vs. 0.5%), although few had moderate or severe gastrointestinal bleeding. The graphs in the paper demonstrate nearly a linear relationship in outcomes over time, so the projected 10-year outcomes indicate that 9% of the placebo-treated patients would have had a coronary event. Recall another study that suggested aspirin's effect was potentially influenced by weight and sex (Lancet. 2018;392[10145]:387–399).

Study design: Randomized controlled trial (double-blinded)

Funding source: Industry

Allocation: Concealed

Setting: Outpatient (any)

Reference: Gaziano JM, Brotons C, Coppolecchia R, et al.; ARRIVE Executive Committee. Use of aspirin to reduce risk of initial vascular events in patients at moderate risk of cardiovascular disease (ARRIVE): a randomised, double-blind, placebo-controlled trial. Lancet. 2018;392(10152):1036–1046.