Coronary artery disease (CAD) is the underlying cause of death in one out of seven deaths in the USA. Aspirin therapy has been proven to decrease mortality and major adverse cardiovascular events in patients with CAD. Despite a plethora of studies showing the benefit of aspirin in secondary prevention of cardiovascular events, debate remains regarding the optimal dose due to relatively small studies that had disparate results when comparing patients taking different aspirin dosages. More recently, aspirin dosing has been thoroughly studied in the CAD population with concomitant therapy (such as P2Y₁₂ inhibitors); however, patients in these studies were not randomized to aspirin dose. No randomized controlled trial has directly measured aspirin dosages in a population of patients with established coronary artery disease. In 2015, the Patient-Centered Outcomes Research Institute (PCORI) developed a network, called PCORnet, that includes patient-powered research networks (PPRN) and clinical data research networks (CDRN). The main objective of PCORnet is to conduct widely generalizable observational studies and clinical trials (including large, pragmatic clinical trials) at a low cost. The first clinical trial, called Aspirin Dosing: A Patient-centric Trial Assessing Benefits and Long-term Effectiveness (ADAPTABLE), will randomly assign 20,000 subjects with established coronary heart disease to either low dose (81 mg) or high dose (325 mg) and should be able to finally answer which dosage of aspirin is best for patients with established cardiovascular disease.