Aspirin for 1o Prevention: To Take or Not To Take

It's amazing that a byproduct of the bark of the willow tree can do so much good and yet generate so much controversy.  By now, the general consensus based upon randomized controlled trials is that aspirin is beneficial in 2o prevention of heart disease in men.  It turns out that aspirin doesn't prevent as much heart disease in women as it does stroke, but again, we're discussing 2o prevention.  In other words, the patient already has the disease and we're trying to prevent remanifestation.  This is in contrast to 1o prevention in which we're trying to prevent incident or first manifestation.

So while the waters have been muddied of late such that we've started considering putting aspirin in the water figuratively speaking (think of the polypill), a meta-analysis of six primary prevention trials involving close to 95,000 low risk individuals followed for 6+years demonstrated no net benefit as published in Lancet almost 3 years ago.  More recently, the folks at www.theNNT.com restated the outcomes in numbers we can hopefully understand:  1,667 would have to take aspirin daily to benefit one person in preventing some cardiovascular problem.  No deaths would be averted/prevented.  2,000 would have to take aspirin daily to prevent one non-fatal heart attack while 10,000 would have to take aspirin daily to prevent a non-fatal stroke.  More importantly, 1 in 3,333 taking aspirin daily would be harmed by a major bleeding event requiring hospitalization & transfusion.

On the other side of the fence, a meta-analysis published last summer in the American Journal of Medicine found daily aspirin decreased all-cause mortality in patients without known cardiac disease.  The authors analyzed 9 studies of over 100,000 individuals followed for 3-10yrs taking mostly 75-100mg of aspirin daily (two studies used >300mg/d) in order to arrive at their conclusion.

Which brings me to the latest salvo published last week in the Archives of Internal Medicine in which a meta-analysis of 9 randomized placebo-controlled trials involving more than 100,000 individuals avg 57yo followed for 6 years noted a decrease in nonfatal myocardial infarction but not in cardiovascular or cancer deaths.  Furthermore, the benefit gained was offset by an increase risk of nontrivial bleeding.

So while I'd like to be able to give you a clear cut answer, I'm afraid we're stuck with an I3 rather than an IF diamond.  Rather than make blanket statements & recommendations, we need to discuss individual risk vs benefit calculations with our thus far cardiovascular disease-free patients.

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