How do they know 40mg of aspirin daily instead of 81 isn't just as effective for protection of stable cad patients w/ a lower risk of side effects?

Stable Angina Tx: 44 year old gentleman with a question about aspirin dose in CAD. The American College of Cardiology/American Heart Association guidelines for the management of patients with chronic stable angina give a dosing range of 75-162mg of aspirin per day unless contraindicated to decrease fatal MI, stroke, vascular deaths. A later meta analysis showed similar benefit at 50mg. Trust your MD to set dose.