I actually looked this up earlier, and here's the summary: In 2002, guidelines from some government agency said that people whose risk of heart disease outweigh

I actually looked this up earlier, and here's the summary: In 2002, guidelines from some government agency said that people whose risk of heart disease outweighed their risk of bleeds should take it. Essentially this meant most men over 40. At the time, there was no evidence that daily aspirin decreased total mortality. In 2009, they revised it to exclude a lot more people because of the risk of bleeds. Now maybe they'll exclude even more people. I'm not going to dig the sources up again, but that's what I found. I don't know how long they've been telling people to take it, but I know my dad was taking it in the 80s. His risk factors were being a man in his 40s and mild hypertension. This fits in with a pattern in which doctors jump to conclusions and tell everybody to do something which turns out to be useless or harmful based on scanty evidence.