Appendix (Figure 1). Analytic framework: aspirin to prevent cardiovascular events. CHD = coronary heart disease; CVD = cardiovascular disease; KQ = key question. KQ 1: Does aspirin chemoprevention in patients without known cardiovascular disease reduce the risk for myocardial infarction, stroke, and death? KQ 2: Does aspirin chemoprevention increase major gastrointestinal bleeding, hemorrhagic strokes, or both? KQ 3: What is the balance of benefits and harms for aspirin therapy in patients with different levels of cardiovascular risk?