It's those scientists and clinicians who develop therapies based upon mechanistic biological medical science who drive medical innovation. Conversely, ‘outcomes’ statisticians take large databases (e.g. the Medicare database) and use them to ‘answer’ questions they ask about whether therapies are effective. For reasons that I'd be more than happy to enumerate and discuss, querying large databases such as the Medicare database is just as likely to yield to erroneous conclusions as it is to lead to meaningful clinically applicable conclusions.
In that context, aspirin is helpful to prevent strokes and myocardial infarctions (heart attacks) because it inhibits the action of platelets. Platelets circulate in the bloodstream, and participate in thrombosis/clot formation. The mechanism of most ‘heart attacks’ is the formation of a clot/thrombus in a coronary artery that already has an atherosclerotic ‘blockage’. The clot/thrombus leads to total occlusion (closure) of the artery - and death of the heart muscle that relies on that artery for delivery of oxygen and nutrients. Taking aspirin makes it less likely that your platelets will participate in forming this thrombus/clot. A similar principle explains why aspirin can help prevent strokes.
One big ‘downside’ of taking aspirin is that is can cause gastritis (erosion of the stomach lining) and predispose to ulcers and bleeding from the GI track. Most people do not have this side-effect, but some do - and this is one of the factors that has lead some outcomes analysts to recommend against taking daily aspirin.
Of course, if you are a thinking physician, you will prescribe daily aspirin to those who are most likely to benefit from it, and not to those who are low risk for thrombus/clot - based events.
The problem with a study like this, that provides no substantive new information, but is sensationalistic and highly visible, is that it can lead to the avoidance of aspirin therapy (or other effective therapies) in those who would benefit from them.
As was hinted to earlier, when it comes to strokes it depends on whether you're at risk for ischemic or hemorrhagic stroke. With the latter, an aspirin regimen will shorten your journey to the afterlife.