There is little controversy surrounding
the use of aspirin for the prevention of
cardiovascular events in patients with
established arteriosclerotic disease(secondary prevention).

There has been a controversy and a confusion
with regard to the use of aspirin for primary prevention.
A recent large meta-analysis
(Arch. Intern. Med. Feb 13, 2012)
which analized more than 100,000 patients
for the primary prevention showed a modest reduction
(10%) of non-fatal myocardial infarction and
total CVD events, but no benefits
with regard to fatal MI, stroke or CVD death or cancer
mortality. This modest benefit was offset
by an elevated risk of nontrivial bleed(30% increase).
The number needed to treat with aspirin
to prevent one nonfatal MI was 162,
compared to the number needed to harm for
nontrivial bleed of 73.

The authors conclude by saying that
"Because the modest benefits of aspirin treatment
for primary prevention were accompanied by
a significant increase in risk of bleeding,
further study is needed to identify
subsets of patients with higher-risk for CVD events.
In the absence of such information,
a reappraisal of current guidelines
appears to be warranted."

In patients for low risk, aspirin may
certainly do more harm.
For those in the middle,
a clinical judgement is certainly required
in each individual patient.
Perhaps creative aspirin dosing, such as
every-other-day, could be explored.

ㅡ from AMA News, February 13, 201