(ACE) inhibitors and statins have all been shown to reduce
death and reinfarction among patients who have experienced an
harmacologic therapy is a mainstay in the secondary
prevention of coronary artery disease. Acetylsalicylic
acid (ASA), β-blockers, angiotensin-converting-enzyme
acute myocardial infarction. Although these medications have
been proven effective in reducing mortality among patients
with coronary artery disease, the magnitude of the reduction
varies across the different medication classes. Meta-analyses
have found that, to avoid 1 death, 83 patients need to receive
ASA for a mean duration of 27 months,1and 42 patients need
to receive β-blockers for 2 years.2In comparison, to avoid 1
death among patients with heart failure or left ventricular dys-
function, 15 patients need to receive ACE inhibitors for 2.5
years.3Finally, 61 patients need to receive statins for a mean
duration of 5.4 years to avoid 1 death.4
Between the late 1980s and mid-1990s, several studies
documented the underuse of evidence-based pharmacologic
therapies among patients with myocardial infarction.5–12Less
is known about the recent trends in the use of these therapies.
We examined the trends in the use of evidence-based drug
therapies after discharge in a population-based sample of
elderly patients diagnosed with myocardial infarction. We
also sought to identify physician and hospital characteristics
associated with a more rapid temporal increase in the use of
Study design and population
We performed a cross-sectional study with a retrospective popu-
lation-based cohort. We used data from the Ontario Myocardial
Infarction Database, a population-based database of patients ad-
mitted to hospital with myocardial infarction in Ontario between
Apr.1, 1992, and Mar. 31, 2005. This database was created by
linking together data from several health care administrative
databases. Its creation is described in greater detail elsewhere.13,14
This database contains data from the Ontario Drug Benefit data-
base, which tracks the use of prescription medications by all
Ontario residents aged 65 years and older. Therefore, our study
was restricted to patients aged 65 years and older who were dis-
charged from hospital with a diagnosis of myocardial infarction.
Peter C. Austin PhD, Jack V. Tu MD PhD, Dennis T. Ko MD MSc, David A. Alter MD PhD
Use of evidence-based therapies after discharge among
elderly patients with acute myocardial infarction
From the Institute for Clinical Evaluative Sciences (Austin, Tu, Ko, Alter); the
Department of Public Health Sciences (Austin) and the Department of
Health Management, Policy and Evaluation (Austin), University of Toronto;
the Schulich Heart Centre and Division of Cardiology, Department of Medi-
cine (Tu, Ko), Sunnybrook Health Sciences Centre; the Department of Medi-
cine, Faculty of Medicine (Tu, Ko), University of Toronto; the Division of Car-
diology and the Li Ka Shing Knowledge Institute (Alter), St. Michael’s
Hospital; The Cardiac and Secondary Prevention Program of the Toronto Re-
habilitation Institute (Alter), Toronto, Ont.
Background: Postdischarge use of evidence-based drug
therapies has been proposed as a measure of quality of care
for myocardial infarction patients. We examined trends in
the use of evidence-based drug therapies after discharge
among elderly patients with myocardial infarction.
Methods: We performed a cross-sectional study in a retro-
spective population-based cohort that was created using
linked administrative databases. We included patients
aged 65 years and older who were discharged from hospi-
tal with a diagnosis of myocardial infarction between
Apr. 1, 1992, and Mar. 31, 2005. We determined the an-
nual percentage of patients who filled a prescription for
statins, β-blockers and angiotensin-modifying drugs within
90 days after discharge.
Results: The percentage of patients who filled a prescription
for a β-blocker increased from 42.6% in 1992 to 78.1% in
2005. The percentage of patients who filled a prescription
for an angiotensin-modifying drug increased from 42.0% in
1992 to 78.4% in 2005. The percentage of patients who
filled a prescription for a statin increased from 4.2% in 1992
to 79.2% in 2005. In 2005, about half of the hospitals had
rates of use for each of these therapies that were less than
80%. The temporal rate of increase in statin use after dis-
charge was slower among noncardiologists than among car-
diologists (3.5%–2.8% slower). The rate of increase was
4.8% slower for among physicians with low volumes of
myocardial infarction patients than among those with high
volumes of such patients and was 5.7% greater at teaching
hospitals compared with nonteaching hospitals.
Interpretation: Use of statins, β-blockers and angiotensin-
modifying drugs increased from 1992 to 2005. The rate of
increase in the use of these medications after discharge
varied across physician and hospital characteristics.
Une version française de ce résumé est disponible à l’adresse
© 2008 Canadian Medical Association or its licensors
• OCTOBER 21, 2008 • 179(9)
See related research, page 901, related commentary, page 875, and related review, page 909
There are limitations to our study. First, we used administra-
tive data, which did not allow us to exclude patients who had
contraindications to the therapies under consideration. How-
ever, as found elsewhere,19it is likely that postdischarge med-
ication use is even higher among ideal patients for whom
therapy is indicated and who have no contraindications than it
is in the entire population of patients with myocardial infarc-
tion. Furthermore, our use of administrative data allowed us
to examine use of prescription medications by all elderly pa-
tients with myocardial infarction in our jurisdiction. The data
for our study were from a population-based database of inci-
dent hospital admissions of patients with myocardial infarc-
tion in Ontario. Therefore, our data are comprehensive and
not restricted to only tertiary centres or to a registry that is
subject to voluntary enrolment.
A second limitation is that we reported the percentage of
patients who filled a prescription. We were unable to capture
prescriptions that were not filled by the patient. Therefore,
our results likely underestimate postdischarge prescribing.
A third limitation is that our analyses were restricted to
patients aged 65 and older. Earlier studies have shown that
prescribing of evidence-based therapies after myocardial
infarction decreases with increasing age.6,7,11Thus, the use of
these therapies is likely even higher among younger patients.
Prescriptions for β-blockers, angiotensin-modifying agents
and statins are currently filled by about 80% of elderly
patients with myocardial infarction after discharge from hos-
pital. However, there was moderate variation in hospital-
specific rates of use of these therapies, with about half of all
hospitals prescribing these medications to less than 80% of
patients. Furthermore, the rate of increase in use of evidence-
based drug therapies use depended on physician and hospital
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CMAJ • OCTOBER 21, 2008 • 179(9)
This article has been peer reviewed.
Competing interests: David Alter is the chief scientific officer of
INTERxVENT Canada. No competing interests declared by Peter Austin,
Jack Tu or Dennis Ko.
Contributors: Peter Austin and Jack Tu contributed substantially to the con-
ception and design of the article. All of the authors contributed to the inter-
pretation of data. Peter Austin drafted the article; Dennis Ko, David Alter and
Jack Tu revised the manuscript critically for important intellectual content.
All of the authors approved the version submitted for publication. Peter
Austin had full access to all of the data in the study and takes responsibility for
the integrity of the data and the accuracy of the data analyses.
Acknowledgements: The Institute for Clinical Evaluative Sciences is sup-
ported in part by a grant from the Ontario Ministry of Health and Long-Term
Care. The opinions, results and conclusions are those of the authors, and no
endorsement by the Ontario Ministry of Health and Long-Term Care or by the
Institute for Clinical Evaluative Sciences is intended or should be inferred.
Peter Austin is supported in part by a Career Scientist Award from the Heart
and Stroke Foundation of Ontario. Dennis Ko is supported by a Clinician–
Correspondence to: Dr. Peter C. Austin, Institute for Clinical
Evaluative Sciences, Rm. G1 06, 2075 Bayview Ave., Toronto ON
M4N 3M5; fax 416 480-6048; firstname.lastname@example.org
Funding: This research was supported by an operating grant from the Heart
and Stroke Foundation of Ontario and a Canadian Institutes of Health Research
Team Grant in Cardiovascular Outcomes Research.
Scientist Award by the Heart and Stroke Foundation of Ontario. Jack Tu holds a
Canada Research Chair in Health Services Research and a Career Investigator
Award from the Heart and Stroke Foundation of Ontario.