Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness - ADAPTABLE

Contribution To Literature:

The ADAPTABLE trial failed to show that aspirin 325 mg was superior to 81 mg in ASCVD patients.


The goal of the trial was to evaluate aspirin 81 mg compared with 325 mg among patients with established atherosclerotic cardiovascular disease (ASCVD).

Study Design

  • Randomized
  • Parallel
  • Open-label

Patients with ASCVD were randomized to aspirin 81 mg (n = 7,540) versus aspirin 325 mg (n = 7,536).

  • Total number of enrollees: 15,076
  • Duration of follow-up: 26.2 months
  • Mean patient age: 68 years
  • Percentage female: 31%
  • Percentage with diabetes: 38%

Inclusion criteria:

  • Patients with CVD, defined as: 1) prior myocardial infarction (MI), 2) prior coronary revascularization, 3) prior coronary angiogram with ≥75% coronary stenosis, or 4) history of chronic ischemic heart disease, coronary artery disease (CAD), or ASCVD.
  • At least one additional enrichment factor:
  • Age ≥65 years
  • Creatinine ≥1.5 mg/dl
  • Diabetes mellitus
  • Known three-vessel CAD
  • Cerebrovascular disease
  • Peripheral artery disease
  • Current smoker
  • Known left ventricular ejection fraction <50%
  • Chronic systolic or diastolic heart failure
  • Systolic blood pressure ≥140 mm Hg within the last year
  • Low-density lipoprotein cholesterol ≥130 mg/dl within the last year

Exclusion criteria:

  • Significant allergy to aspirin
  • Gastrointestinal bleeding within the last 12 months
  • Bleeding disorder that precluded aspirin
  • Current or planned use of an oral anticoagulant or ticagrelor
  • Female patients who are pregnant or nursing

Other salient features/characteristics:

  • Aspirin use before the study: 81 mg in 85%, 162 mg in 2.5%, and 325 mg in 12.3%

Principal Findings:

  • The primary effectiveness outcome of all-cause death, MI, or stroke at 12 months occurred in 7.3% of the aspirin 81 mg group compared with 7.5% of the aspirin 325 mg group (p = 0.75).
  • The primary safety outcome of major bleeding requiring blood transfusion at 12 months occurred in 0.6% of the aspirin 81 mg group compared with 0.6% of the aspirin 325 mg group (p = 0.41).
  • The secondary outcome of dose switching occurred in 7.1% in the aspirin 81 mg group compared with 41.6% of the aspirin 325 mg group.


Among patients with ASCVD, aspirin 325 mg was not superior compared with 81 mg. Aspirin 325 mg was not associated with a reduction in all-cause death, MI, or stroke compared with 81 mg daily. Major bleeding requiring transfusion was similar between treatment groups. Patients assigned to aspirin 325 mg were more likely to switch to a lower dose than vice versa. In 2014, results from the National Cardiovascular Data Registry revealed that 60% of patients with acute MI were discharged on a dose of 325 mg. However, prior to randomization in ADAPTABLE, 85% of patients were treated with 81 mg, reflecting a change in practice pattern. For most patients with established ASCVD, aspirin 81 mg likely remains preferential due to enhanced adherence.


Jones WS, Mulder H, Wruck LM, et al., on behalf of the ADAPTABLE Team. Comparative Effectiveness of Aspirin Dosing in Cardiovascular Disease. N Engl J Med 2021;384:1981-90.

Editorial: Baigent C. Pragmatic Trials — Need for ADAPTABLE Design. N Engl J Med 2021;384:2065-6.

Presented by Dr. William Schuyler Jones at the American College of Cardiology Virtual Annual Scientific Session (ACC 2021), May 15, 2021.

Clinical Topics: Anticoagulation Management, Cardiac Surgery, Dyslipidemia, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Prevention, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Cardiac Surgery and SIHD, Lipid Metabolism, Nonstatins, Acute Heart Failure, Interventions and Coronary Artery Disease, Interventions and Imaging, Interventions and Vascular Medicine, Angiography, Nuclear Imaging, Smoking

Keywords: ACC21, ACC Annual Scientific Session, Angina Pectoris, Angiography, Anticoagulants, Aspirin, Atherosclerosis, Blood Pressure, Cholesterol, LDL, Coronary Artery Disease, Coronary Stenosis, Creatinine, Diabetes Mellitus, Heart Failure, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Peripheral Arterial Disease, Secondary Prevention, Smoking, Stroke, Vascular Diseases

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