This article reviews the relevant published literature in order to ass
ess whether aspirin (acetylsalicylic acid, ASA) is underused in myocar
dial infarction (MI), taking into account: (i) the evidence of efficac
y and safety from clinical trials; (ii) authorirative recommendations
about its use; and (iii) published drug-utilisation studies. The use o
f low-dosage aspirin in the acute phase of MI, and as secondary preven
tion, should be recommended to all patients who do not have contraindi
cations to the drug. This is a solid evidence-based recommendation wit
h potential benefits that are, at least, similar to those obtained wit
h other standard treatments. As this treatment is well tolerated and i
nexpensive, it is also assumed that net savings can be achieved. No co
nventionally used prophylactic aspirin regimen seems to be free from t
he risk of serious gastrointestinal toxicity. This is especially impor
tant in primary prevention, in which the benefits are small; there is.
as yet, no clear evidence that aspirin is indicated for routine use i
n patients ut low risk of occlusive vascular events. We have identifie
d 21 published drug-utilisation studies, and the potential underuse of
aspirin in MI was not properly assessed in most of them. In these stu
dies, fairly high aspirin prescription rates were usually documented.
However. it seems clear that there is room for improvement. and that a
significant proportion of patients who could have benefited from aspi
rin did not receive it or received less well-studied and more costly d
rugs. The prescription rates for other drugs with proven efficacy have
been lower, and the potential underuse greater, than those documented
for aspirin.