Aspirin's benefits and harms are less clear for primary prevention in moderate-risk patients (ARRIVE)

Reference

Gaziano JM, Brotons C, Coppolecchia R, et al, for the 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.

Synopsis

Low-dose aspirin for secondary prevention and in the face of acute coronary events is pretty much a slam dunk. But despite of years of research, several meta-analyses, and numerous guidelines, its use for primary prevention still seems to rile people up. These 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. So, they conducted a double-blind randomized trial of 100 mg aspirin daily (n = 6270) or placebo (n = 6276) in patients at 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 and those at high risk for bleeding complications. Using intention-to-treat analysis, after 5 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 very 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 last month another study that suggested aspirin's effect was potentially influenced by weight and sex (Rothwell et al. Lancet 2018;392(10145):387-399).