BACKGROUND AND PURPOSE:

• There is evidence that low-dose aspirin is beneficial to those individuals who have acute coronary syndromes or previous myocardial infarction, stroke or TIA
• The use of low-dose aspirin in those at moderate risk to prevent a first cardiovascular event is controversial
• There is evidence that aspirin may prevent colon cancer
• Gaziano et al. (The Lancet, 2018) assessed the efficacy and safety of aspirin in patients with moderate estimated risk of a first cardiovascular event

METHODS:

• Randomized, double-blind, placebo-controlled, multicenter study (RCT)
  • Patients at moderate risk of cardiovascular disease (CD)
  • Moderate risk: 10-year risk of coronary heart disease of 10-20%
• Risk Factors
  • High cholesterol
    • Men: Total cholesterol >200 mg/dL (5.180 mmol/L) or LDL >130 mg/dL (3.367 mmol/L)
    • Women: Total cholesterol >240 mg/dL (6.126 mmol/L) or LDL >160 mg/dL (4.144 mmol/L)
  • Current smoking: Any cigarette smoking in the past 12 months
  • Low HDL cholesterol: <40 mg/dL
  • High blood pressure: Systolic BP >140 mm Hg
  • Receiving medication to treat high blood pressure
  • Positive family history of CVD
• Patients
  • Men: ≥55 years | 2 to 4 risk factors
  • Women: ≥60 years | ≥3 risk factors
• Patients were randomly assigned to receive either
  • Enteric-coated aspirin tablets (100 mg)
  • Placebo tablets
• Median follow up was 60 months
• Primary outcome: Composite outcome of
  • Time to first occurrence of cardiovascular death | Myocardial infarction | Unstable angina | Stroke | TIA
• Safety endpoints
  • Hemorrhagic events
  • Incidence of other adverse events

RESULTS:

• 12,546 patients were enrolled and randomized
  • Aspirin 6270 | Placebo 6276
• Fatal or non-fatal myocardial infarction was similar between groups (p=0.2325)
  • 1.52% patients in the aspirin group
  • 1.78% patients in the placebo group
  • Hazard ratio (HR) 0.85; 95% CI, 0.64–1.11
• Composite cardiovascular outcome was similar between the 2 groups (p=0·6038)
  • 269 (4.29%) patients in the aspirin group
  • 281 (4.48%) patients in the placebo group
  • HR 0.96; 95% CI, 0.81–1.13
• There was no significant difference in myocardial infarction in the intention-to-treat group, although this was significant in the ‘in-protocol’ group
• Gastrointestinal bleeding events (mostly mild) occurred more commonly in the aspirin group (p=0·0007)
  • 61 (0.97%) patients in the aspirin group
  • 29 (0.46%) in the placebo group
  • HR 2.11; 95% CI, 1.36–3.28
• The overall incidence of adverse events was similar in both treatment groups
• Overall incidence of treatment-related adverse events was more common in the aspirin group (p<0.0001)
  • 16.75% patients in the aspirin group
  • 13.54% in the placebo group
• There were 321 documented deaths and were similar in both groups
  • 2.55% in the aspirin group vs 2.57% in the placebo group

CONCLUSION:

• The event rate was lower than predicted and therefore reflects a low-risk rather than moderate-risk population (reflective of improved medical management)
• The study, therefore, does not address moderate-risk individuals
• In low risk patients, there needs to be a balance between low prevention impact and high bleeding risk of low-risk aspirin for those at low-risk CD populations

Learn More – Primary Sources:

Use of aspirin to reduce risk of initial vascular events in patients at moderate risk of cardiovascular disease: a randomized, double-blind, placebo-controlled trial

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