Aspirin 50 mg vs. 100 mg in Elderly Cardiovascular Disease Patients

Elderly patients with cardiovascular disease face a high risk of both thrombotic and bleeding events when receiving antithrombotic therapy. The optimal dose of aspirin for secondary prevention in this population remains uncertain, particularly in Chinese elderly individuals. This multicenter, prospective cohort study aims to evaluate the effectiveness and safety of a lower dose of aspirin (50 mg daily) compared with the standard dose (100 mg daily) for secondary prevention of atherosclerotic cardiovascular disease (ASCVD) in Chinese patients aged 60 years and older. The study is an extension of the existing LAPIS cohort (ChiCTR1900021980), which has enrolled 5,448 participants receiving long-term aspirin for secondary prevention. Participants will be followed for an additional 2 years (total follow-up up to approximately 6 years) through telephone, clinic visits, and electronic medical records. The primary effectiveness outcome is the first occurrence of major adverse cardiovascular events (MACE), including non-fatal myocardial infarction, unstable angina, need for revascularization, non-fatal stroke, transient ischemic attack, and cardiovascular death (excluding intracranial bleeding). The primary safety outcome is the first occurrence of bleeding events (classified by BARC criteria). A secondary aim is to develop and validate a risk prediction model (nomogram) for thrombotic and bleeding events specifically for elderly Chinese patients receiving antithrombotic therapy, using LASSO regression and Cox proportional hazards models. The study will provide real-world evidence to guide individualized antithrombotic management in the aging Chinese population.