Key result
Primary prevention aspirin reduces nonfatal MI and ischemic stroke but increases major bleeding ~50%.
Why the study?
The efficacy and safety of aspirin for primary prevention of cardiovascular disease remained debatable following the publication of recent large trials that added over 45,000 individuals.
Does aspirin reduce cardiovascular events in individuals for primary prevention of cardiovascular disease?
Meta-Analysis (n=165,502)
Does aspirin reduce cardiovascular events in individuals for primary prevention of cardiovascular disease?
Aspirin for primary prevention of cardiovascular disease reduces nonfatal ischemic events but significantly increases the risk of major bleeding.
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“We need to stop debating whether aspirin prophylaxis is cardiovascularly beneficial, because it clearly isn't. What we need to do is stop prescribing it to patients and focus on the stuff that matters more.”
“There are now 13 major clinical trials in primary prevention with more than 160,000 participants. The trials continue to show about a 10% reduction in major CVD events, 11% significant reduction in total MI, 9% reduction in total stroke, and 18% reduction in ischemic stroke, but also substantial increase in the risk for bleeding — about a 58% increased risk for GI bleeding, 31% increase in intracranial bleeding, and overall 44% increase in risk for major bleeding.”
“What is critically important is the benefit-risk assessment for the individual patient. It will vary substantially from patient to patient in terms of what their underlying CVD risk is, what their bleeding risk factors are and also their personal preferences regarding use of aspirin.”
Individualized benefit-risk assessment should guide aspirin primary prevention; confirms ~10% CVD event reduction across 13 major trials.
BACKGROUND The efficacy and safety of aspirin for primary prevention of cardiovascular disease (CVD) remain debatable. OBJECTIVES The purpose of this study was to examine the clinical outcomes with aspirin for primary prevention of CVD after the recent publication of large trials adding >45,000 individuals to the published data. METHODS Randomized controlled trials comparing clinical outcomes with aspirin versus control for primary prevention with follow-up duration of ≥1 year were included. Efficacy outcomes included all-cause death, cardiovascular (CV) death, myocardial infarction (MI), stroke, transient ischemic attack (TIA), and major adverse cardiovascular events. Safety outcomes included major bleeding, intracranial bleeding, fatal bleeding, and major gastrointestinal (GI) bleeding. Random effects DerSimonian-Laird risk ratios (RRs) for outcomes were calculated. RESULTS A total of 15 randomized controlled trials including 165,502 participants (aspirin n = 83,529, control n = 81,973) were available for analysis. Compared with control, aspirin was associated with similar all-cause death (RR: 0.97; 95% confidence interval [CI]: 0.93 to 1.01), CV death (RR: 0.93; 95% CI: 0.86 to 1.00), and non-CV death (RR: 0.98; 95% CI: 0.92 to 1.05), but a lower risk of nonfatal MI (RR: 0.82; 95% CI: 0.72 to 0.94), TIA (RR: 0.79; 95% CI: 0.71 to 0.89), and ischemic stroke (RR: 0.87; 95% CI: 0.79 to 0.95). Aspirin was associated with a higher risk of major bleeding (RR: 1.5; 95% CI: 1.33 to 1.69), intracranial bleeding (RR: 1.32; 95% CI: 1.12 to 1.55), and major GI bleeding (RR: 1.52; 95% CI: 1.34 to 1.73), with similar rates of fatal bleeding (RR: 1.09; 95% CI: 0.78 to 1.55) compared with the control subjects. Total cancer and cancer-related deaths were similar in both groups within the follow-up period of the study. CONCLUSIONS Aspirin for primary prevention reduces nonfatal ischemic events but significantly increases nonfatal bleeding events.
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Abdelaziz et al. (2019) conducted a meta-analysis in primary prevention of cardiovascular disease (n=165,502). Aspirin vs. Control was evaluated on all-cause death (RR 0.97, 95% CI 0.93 to 1.01). Aspirin for primary prevention reduced nonfatal MI (RR 0.82; 95% CI 0.72-0.94) and ischemic stroke, but increased major bleeding (RR 1.5; 95% CI 1.33-1.69).
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