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Family practice patients’ use of acetylsalicylic acid for cardiovascular disease prevention

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To determine the prevalence of acetylsalicylic acid (ASA) use among family practice patients and the proportions of patients using ASA for primary and secondary cardiovascular prevention. Cross-sectional, self-reported, waiting room questionnaire. Two family medicine clinics in Alberta. Patients 50 years of age and older. Overall prevalence of ASA use, proportion of ASA use for primary or secondary cardiovascular prevention, ASA use by patient age and sex, the proportion of patients who initiated ASA therapy on the advice of a physician, adverse events, and patient beliefs about ASA therapy. A total of 807 patients completed the questionnaire; the response rate was 89.1%. Overall, 39.8% of patients reported taking ASA regularly. Of those who took ASA, 87.0% did so for cardiovascular prevention (53.1% for primary prevention and 46.9% for secondary prevention). Of patients taking ASA for primary prevention, 62.8% did so upon the advice of their family physicians. Patients who took ASA believed that the benefits of taking ASA outweighed the risks; those who did not take ASA were unsure of the benefit-to-risk profile. Many family practice patients take ASA, and more than half of those taking ASA take it for primary cardiovascular prevention. Family physicians appear to have an influence on patients' decisions to take ASA. Educating family physicians and patients about the potential benefits and risks of ASA therapy would help promote the use of ASA in those who might receive the greatest overall benefit.
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VOL 59: JANUARY JANVIER 2013
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Canadian Family Physician Le Médecin de famille canadien
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Research
This article has been peer reviewed.
Can Fam Physician
2013;59:55-61
Family practice patientsuse of acetylsalicylic
acid for cardiovascular disease prevention
Michael Kolber MD MSc CCFP Nadder Sharif MSc MD CCFP(EM) Raelene Marceau MN NP Olga Szafran MHSA
Abstract
Objective  To determine the prevalence of acetylsalicylic acid (ASA) use among family practice patients and the
proportions of patients using ASA for primary and secondary cardiovascular prevention.
Design  Cross-sectional, self-reported, waiting room questionnaire.
Setting  Two family medicine clinics in Alberta.
Participants  Patients 50 years of age and older.
Mai noutcome measures  Overall prevalence of ASA use, proportion of
ASA use for primary or secondary cardiovascular prevention, ASA use by
patient age and sex, the proportion of patients who initiated ASA therapy
on the advice of a physician, adverse events, and patient beliefs about
ASA therapy.
Results  A total of 807 patients completed the questionnaire; the response
rate was 89.1%. Overall, 39.8% of patients reported taking ASA regularly.
Of those who took ASA, 87.0% did so for cardiovascular prevention (53.1%
for primary prevention and 46.9% for secondary prevention). Of patients
taking ASA for primary prevention, 62.8% did so upon the advice of
their family physicians. Patients who took ASA believed that the benefits
of taking ASA outweighed the risks; those who did not take ASA were
unsure of the benefit-to-risk profile.
Conclusion  Many family practice patients take ASA, and more than half
of those taking ASA take it for primary cardiovascular prevention. Family
physicians appear to have an influence on patients’ decisions to take ASA.
Educating family physicians and patients about the potential benefits and
risks of ASA therapy would help promote the use of ASA in those who
might receive the greatest overall benefit.
EDITOR’S KEY POINTS
This study showed that 39.8% of family
practice patients took acetylsalicylic
acid (ASA) regularly; 87.0% did so
for cardiovascular prevention (53.1%
for primary prevention and 46.9% for
secondary prevention).
A significantly greater proportion of men
than women took ASA for cardiovascular
prevention (
P
< .001). There was also a
significant association (
P
< .001) between
ASA use and age, as patients in the 70- to
79-year-old age group were more likely to
use ASA for cardiovascular prevention than
patients in the 50- to 59-year-old age group
were. The proportion of patients using ASA
for secondary cardiovascular prevention was
higher in the older age groups.
Although most patients appear to initiate
the use of ASA upon the advice of their
family physicians, about one-quarter
start taking ASA themselves for primary
prevention. Family physicians and patients
need to be educated about the potential
benefits and risks of ASA therapy. It is
likely that many patients of relatively
low cardiovascular risk are taking ASA for
primary cardiovascular prevention, while
many of those who might benefit from
ASA for secondary prevention are not
taking it.
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56
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Utilisation de lacide acétylsalicylique pour
prévenir les maladies cardiovasculaires chez les
patients de pratiques de médecine familiale
Michael Kolber MD MSc CCFP Nadder Sharif MSc MD CCFP(EM) Raelene Marceau MN NP Olga Szafran MHSA
Résumé
Objectif Déterminer la prévalence d’utilisation de l’acide acétylsalicylique (AAS) chez des patients de médecine
familiale et la proportion de ceux qui utilisent cet agent en prévention cardiovasculaire primaire ou secondaire.
Type d’étude  Étude transversale basée sur les réponses des patients à un questionnaire complété en salle d’attente.
Contexte  Deux cliniques de médecine familiale de l’Alberta.
Participants  Patients de 50 ans et plus.
Principaux  paramètres  à  l’étude  Prévalence globale de l’utilisation de
l’AAS, proportion de l’utilisation de l’AAS en prévention cardiovasculaire
primaire et secondaire, utilisation selon l’âge et le sexe des patients,
proportion de ceux qui avaient commencé à prendre de l’AAS sur le
conseil d’un decin, effets indésirables et croyances des patients au
sujet du traitement à l’AAS.
Résultats  Un total de 807 patients ont complété le questionnaire, pour
un taux de réponse de 89,1 %. Dans lensemble, 39,8 % des patients
déclaraient prendre de l’AAS gulièrement. Parmi ces derniers, 87,0 %
lutilisaient en prévention cardiovasculaire (53,1 % en prévention
primaire et 46,9 % en prévention secondaire). Parmi les patients qui en
consommaient en prévention primaire, 62,8 % le faisaient sur le conseil de
leur médecin de famille. Les patients qui prenaient de l’AAS croyaient qu’il
y avait plus d’avantages que d’inconvénients à prendre de l’AAS : ceux
qui n’en prenaient pas ne connaissaient pas suffisamment le rapport
avantages/risques.
Conclusion Plusieurs patients des cliniques de médecine familiale
prennent de lAAS et plus de la moitié dentre eux le font pour la
pvention cardiovasculaire primaire. Le médecin semble avoir une
influence pour décider les patients à prendre de l’AAS. Renseigner les
médecins de famille et les patients sur les avantages et les risques
potentiels d’un traitement à l’AAS aiderait à promouvoir l’utilisation de
l’AAS auprès de ceux qui pourraient en profiter le plus.
Recherche
Cet article a fait l’objet d’une vision par des pairs.
Can Fam Physician
2013;59:55-61
This article is eligible for Mainpro-M1 credits. To earn
credits, go to www.cfp.ca and click on the Mainpro link.
Cet article donne droit à des crédits Mainpro-M1.
Pour obtenir des crédits, allez à www.cfp.ca et cliquez sur le lien vers Mainpro.
POINTS DE REPÈRE DU RÉDACTEUR
Cette étude a montré que 39,8 % des
patients de médecine familiale prenaient
de l’acide acétylsalicylique (AAS) de façon
régulière : 87,0 % en prenaient pour la
prévention cardiovasculaire (53,1 % pour
la prévention primaire et 46,9 % pour la
prévention secondaire).
Une proportion significativement
plus élevée d’hommes que de femmes
prenaient de l’AAS pour la prévention
cardiovasculaire (
P
< ,001). On notait
également une association significative
(
P
< ,001) entre le fait de prendre de l’AAS
et l’âge des patients, les 70-79 ans étant
plus susceptibles que les 50-59 ans d’en
prendre pour la prévention cardiovasculaire.
La proportion de patients qui prenaient de
l’AAS pour la prévention secondaire était
plus élevée dans les groupes plus âgés.
Même si la plupart des participants
semblent avoir commencé à prendre l’AAS
sur l’avis de leur médecin de famille, environ
un quart d’entre eux avaient décidé eux-
mêmes d’en prendre à titre de prévention
primaire. Il faudrait renseigner les médecins
de famille et les patients sur les avantages
et les risques éventuels d’un traitement à
l’AAS. Il est probable que plusieurs patients
qui présentent un risque cardiovasculaire
relativement faible prennent de l’AAS pour
la prévention cardiovasculaire primaire,
alors que plusieurs de ceux qui auraient
avantage à en prendre pour la prévention
secondaire n’en prennent pas.
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Family practice patients’ use of acetylsalicylic acid for cardiovascular disease prevention |
Research
A
cetylsalicylic acid (ASA) is commonly used to
decrease the risk of future cardiovascular
events. In the United States, between 36% and
41% of patients 40 years of age and older use ASA
regularly, mostly for primary cardiovascular preven-
tion.
1,2
Acetylsalicylic acid is beneficial in patients with
known cardiovascular disease.
3,4
When used for pri-
mary prevention, ASA might decrease the incidence
of myocardial infarctions in men and ischemic strokes
in women,
5,6
but it has not been shown to decrease
cardiovascular or all-cause mortality.
5,7
Furthermore,
the potential cardiovascular benefits are likely offset
by the potential risk of adverse events, especially in
individuals with lower cardiovascular risk.
6,8,9
Even in
patients at higher risk of future cardiovascular events
(ie, patients with diabetes or hypertension), the litera-
ture does not show a net clinical benefit to using ASA
for primary cardiovascular prevention.
10-14
Although it is assumed that a similar proportion
of Canadians, compared with Americans, regularly
use ASA, no data on the prevalence of ASA use by
Canadians are available in the published literature.
The primary objective of this study was to determine
the prevalence of ASA use in patients 50 years of age
or older and to determine the proportion of patients
using ASA for primary or secondary cardiovascular
prevention. Secondary objectives included examining
ASA use by age and sex, the proportion of patients
who initiated ASA therapy on the advice of a physician,
adverse events attributed to ASA therapy, and patient
beliefs about the benefits and risks of ASA therapy.
METHODS
This was a cross-sectional, waiting room survey con-
ducted over a 4-week period at 2 family practice clinics
(1 rural, 1 urban) in Alberta. The rural family practice
clinic was located in Peace River, Alta, a town with
6315 residents 486 km northwest of Edmonton.
15
The
urban clinic was an academic family medicine practice
located in downtown Edmonton.
Patients 50 years of age and older who attended
either family medicine clinic (for any reason) during
the study period and who were fluent in English were
eligible to take part in the study. The study was con-
ducted from November 23 to December 18, 2009, at
the rural site, and from April 19 to May 14, 2010, at the
urban site. Eligible patients were invited to take part in
the study by the clinic receptionists, and the question-
naire was completed in the clinic waiting room and
returned in a sealed envelope. Consent was implied
by the return of a completed questionnaire. Patients
who had more than 1 visit to the clinic during the study
period completed the questionnaire only once. Ethics
approval was granted by the Health Research Ethics
Board at the University of Alberta.
Questionnaire
The study questionnaire was adapted from previous
ASA prevalence questionnaires,
1,2
including the 2003
Behaviour Risk Factor Surveillance System telephone
questionnaire used by the Centers for Disease Control
and Prevention in the United States.
16
Additional ques-
tions added to our questionnaire included the follow-
ing: whether ASA therapy was initiated by the patient
or physician; what adverse events were potentially
related to ASA use; what actions were taken as a result
of adverse events; and what the patient’s beliefs were
regarding the potential benefits and risks of using
ASA. The questionnaire was assessed for face validity.
Patients were considered to have cardiovascular disease
if they reported any of the following conditions: heart
disease (myocardial infarction, angina, angioplasty, or
cardiac stenting), stroke or transient ischemic attack,
peripheral vascular disease, atrial fibrillation, valvular
heart disease, or congestive heart failure. Patients were
considered not to have cardiovascular disease if they
did not report any of the aforementioned conditions.
Regular ASA use was defined as taking ASA at least every
other day.
1
The questionnaire was anonymous and con-
tained no personally identifiable information.
Data analysis
Study data were analyzed descriptively using SPSS
version 17 for Windows. The calculation of percent-
ages was based on recorded responses. The χ
2
test
was used to determine association between ASA use
and selected variables. A 2-sided α level of .05 was
employed to ascertain statistical significance, and 95%
CIs were reported where applicable.
RESULTS
Respondents
A total of 906 eligible patients (480 rural and 426
urban) visited the family medicine clinics during the
study period. A total of 807 patients (422 rural and 385
urban) completed the survey, yielding an overall partic-
ipation rate of 89.1%. Of those patients who indicated
their sex, 44.4% (355 of 800) were men (44.0% [183
of 416] of the rural group and 44.8% [172 of 384] of
the urban group). Responses revealed that 29.2% (200
of 684) were deemed to have cardiovascular disease
(29.2% [101 of 345] of the rural group and 29.5% [99 of
339] of the urban group) (Table 1). Overall, the mean
age of respondents was 62.6 years (SD 9.9 years), and
urban respondents were older than rural respondents
(64.5 years vs 60.9 years; P < .001).
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Family practice patients’ use of acetylsalicylic acid for cardiovascular disease prevention
Prevalence of ASA use
Of the 798 respondents who
indicated whether or not they
took ASA, 318 (39.8%) (95%
CI 35.6 to 42.4) used ASA reg-
ularly, and 87.0% (274 of 315)
of them used it for cardiovas-
cular prevention (Figure 1).
Of the 274 patients who took
ASA for cardiovascular pre-
vention, 53.1% (95% CI 46.8
to 59.4) used ASA for primary
prevention and 46.9% (95%
CI 40.6 to 53.2) for second-
ary prevention. Conversely,
of the 200 patients who
reported having underlying
cardiovascular disease, 62.5%
took ASA.
Prole of ASA users
A significantly greater pro-
portion of men than women
took ASA for cardiovascu-
lar prevention (40.8% [145 of
355] vs 28.5% [127 of 445];
P < .001). Relatively more
men than women took ASA
for secondary prevention
(50.0% vs 43.6%) than for
primary prevention (50.0%
vs 56.3%); however, these
differences were not statis-
tically significant.
There was a significant association (P < .001) between
ASA use and age, with those in the 70- to 79-year-
old age group (49.2%) being most likely to use ASA
for cardiovascular prevention and those in the 50- to
59-year-old age group (24.7%) being least likely to use
ASA for cardiovascular prevention. The proportion of
patients using ASA for secondary cardiovascular pre-
vention increased with older age, with 41.0%, 46.3%,
50.9%, and 60.9% of those aged 50 to 59 years, 60 to 69
years, 70 to 79 years, and 80 years and older, respect-
ively, using ASA for secondary prevention.
There was no difference between the rural and urban
patient groups in the proportion who used ASA for
cardiovascular prevention (31.3% rural, 36.9% urban),
but significantly more urban patients (60.8% urban vs
44.2% rural; P = .01) were taking ASA for primary cardio-
vascular prevention.
Who initiated ASA use
Overall, 85.0% (233 of 274) of patients started ASA for
cardiovascular prevention owing to the advice of health
care providers, 67.5% because of advice from their family
Table 1. Characteristics of respondents, by rural and
urban areas
CHARACTERISTICS
RURAL
N = 422,
N (%)*
URBAN
N = 385,
N (%)*
TOTAL
N = 807,
N (%)*
Sex
Male 183 (43.4) 172 (44.7) 355 (44.0)
Female 233 (55.2) 212 (55.1) 445 (55.1)
Not recorded 6 (1.4) 1 (0.3) 7 (0.9)
Age group
50-59 y 220 (52.1) 141 (36.6) 361 (44.7)
60-69 y 130 (30.8) 118 (30.6) 248 (30.7)
70-79 y 53 (12.6) 77 (20.0) 130 (16.1)
80 y 15 (3.6) 43 (11.2) 58 (7.2)
Not recorded 4 (0.9) 6 (1.6) 10 (1.2)
Have CVD
Yes 101 (23.9) 99 (25.7) 200 (24.8)
No 244 (57.8) 240 (62.3) 484 (60.0)
Not recorded 77 (18.2) 46 (11.9) 123 (15.2)
CVD—cardiovascular disease.
*Percentages might not add to 100 owing to rounding.
Figure 1. Prevalence of ASA use among respondents
Respondents
(N=807)
Recorded responses
98.9%
(n=798 of 807)
Take ASA for
cardiovascular
prevention
87.0%
(n=274 of 315)
Primary
cardiovascular prevention
53.1%
(n=129 of 243)
Secondary
cardiovascular prevention
46.9%
(n=114 of 243)
Do not know or
not recorded
11.3%
(n=31 of 274)
Do not take ASA
60.2%
(n=480 of 798)
Take ASA
39.8%
(n=318 of 798)
Do not know
or not recorded
1.1%
(n=9 of 807)
ASA—acetylsalicylic acid.
*For example, pain relief, 8.6% (27 of 315).
Take ASA for
other reasons*
13.0%
(n=41 of 315)
Reason not recorded
0.9%
(n=3 of 318)
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Family practice patients’ use of acetylsalicylic acid for cardiovascular disease prevention |
Research
physicians (Table 2). Family physicians were equally
likely to prescribe ASA for primary or secondary cardio-
vascular prevention. A significantly greater proportion of
patients who took ASA for primary (26.4%) versus sec-
ondary (3.5%) prevention initiated ASA therapy by them-
selves (P < .001). Specialists initiated ASA therapy for a
greater proportion of patients who took ASA for second-
ary (25.4%) versus primary prevention (8.5%) (P < .001).
Potential adverse events
Of all those who used ASA for cardiovascular preven-
tion, 6.9% (19 of 274) of patients experienced adverse
events potentially related to ASA therapy. Adverse
events that were reported included the following (more
than 1 adverse event per patient possible): abdominal
pain,
6
gastrointestinal bleeding,
3
nosebleeds,
5
renal
problems,
1
and other.
10
Of those patients using ASA for primary preven-
tion, 6.2% (8 of 129) reported adverse events potentially
related to ASA therapy, 50.0% of whom (4 of 8) con-
tinued taking ASA after the adverse events. Similarly,
7.0% (8 of 114) of patients using ASA for secondary pre-
vention reported adverse
events, 62.5% of whom (5 of
8) continued taking ASA.
Patient beliefs
The question about per-
ceived benefits and risks of
ASA therapy was answered
by 91.1% of all respondents.
Overall, 66.9% of patients
who took ASA believed that
the potential benefits of ASA
therapy outweighed the
potential risks (Figure 2). Of
those who did not use ASA,
68.8% of respondents were
unsure whether the poten-
tial benefits of ASA ther-
apy outweighed the risks.
Irrespective of whether respondents were ASA users or
not, only 5.0% believed the potential risks of ASA ther-
apy outweighed the potential benefits.
Of patients who used ASA for cardiovascular preven-
tion, 70.9% believed that the potential benefits of ASA
therapy outweighed the potential risks. This belief did
not differ between patients who were taking ASA for
primary prevention and those who were taking it for
secondary prevention.
DISCUSSION
This is the first study to examine the prevalence of ASA
use among family practice patients in Canada. Similar
to previous studies,
1,2
approximately 40% of family prac-
tice patients older than 50 years of age in our study used
ASA, mainly to prevent future cardiovascular events.
Applying the prevalence rate of ASA use observed in
this study to the 2009 Canadian population census
data,
17
an estimated 4 million Canadians aged 50 years
or older might be using ASA for cardiovascular preven-
tion. Given that both patients and physicians tend to
overestimate cardiovascular risk,
18,19
many patients of
relatively low cardiovascular risk are likely taking ASA
for primary cardiovascular prevention.
Primary and secondary prevention
D
espite evidence questioning the benefit of ASA in pri-
mary cardiovascular prevention,
5,7
more family prac-
tice patients used ASA for primary than for secondary
cardiovascular prevention. This might be attributed to
several reasons. First, after an early North American
study demonstrated decreased cardiac events,
20
ASA
was widely promoted for primary cardiovascular
prevention. Over time, despite new evidence, patients
and physicians might be reluctant to discontinue ASA
Figure 2. Patient beliefs about benets of ASA therapy: Responses were
signicantly different for patients who took ASA and those who did not
(P< .001).
80
70
60
50
40
30
20
10
0
PATIENTS, %
BELIEFS ABOUT ASA THERAPY
Benets > risk Benets < risk Not sure
ASA—acetylsalicylic acid.
Take ASA
Do not take ASA
66.9%
24.5%
2.7%
6.7%
30.4%
68.8%
Table 2. Who initiated ASA therapy
INITIATOR
OVERALL CV
PREVENTION
N = 274,
N (%)*
PRIMARY CV
PREVENTION
N = 129,
N (%)
SECONDARY CV
PREVENTION
N = 114,
N (%)
Patient 39 (14.2) 34 (26.4) 4 (3.5)
Family physician 185 (67.5) 80 (62.0) 79 (69.3)
Other specialist 43 (15.7) 11 (8.5) 29 (25.4)
Other health care
provider
5 (1.8) 4 (3.1) 2 (1.8)
Do not know or
not recorded
2 (0.7) 0 (0.0) 0 (0.0)
ASA—acetylsalicylic acid, CV—cardiovascular.
*Percentages might not add to 100 owing to rounding.
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Family practice patients’ use of acetylsalicylic acid for cardiovascular disease prevention
therapy in the absence of adverse events. Second,
guidelines still continue to recommend or consider
ASA therapy for patients without cardiovascular dis-
ease.
8,21-23
Finally, direct-to-consumer advertising
might have influenced patients’ decisions to continue
to use ASA therapy, as shown by the 26.4% of primary
prevention patients in our study who started ASA by
themselves.
Overall, more men than women in our study took
ASA for cardiovascular prevention. This is consistent
with current Canadian data that illustrate that cardio-
vascular disease is more prevalent in men.
24
Analysis
of ASA use by age revealed that proportionally more
patients were using ASA for secondary prevention
with increasing age groups. This is also consistent
with the higher prevalence of cardiovascular disease
with increasing age.
24
The finding that more patients in the urban clinic
were taking ASA for primary cardiovascular preven-
tion when compared with the rural clinic might reflect
differing practice patterns of the physicians or different
cardiovascular risk profiles between patients at the 2
sites. The urban clinic had older patients than the rural
clinic did; therefore, these patients might be at increased
risk of cardiovascular disease, resulting in more of them
using ASA.
In our study, 4 out of 8 patients who took ASA for
primary prevention continued to use ASA despite
experiencing adverse events. This was surprising,
given that the potential risks of ASA therapy have
been well documented.
25,26
Acetylsalicylic acid is a
leading cause of both hospital admissions and deaths
from medication-related adverse events,
9,27
and recent
evidence questions the benets of ASA for primary
cardiovascular prevention.
5,7
Taken together, this sug-
gests that health care providers should attempt to
minimize the use of ASA for primary prevention, espe-
cially in those at low cardiovascular risk. Furthermore,
family physicians should consider discontinuing ASA
in primary prevention patients who experienced
adverse events related to ASA therapy. The nature and
severity of the adverse event, the indication for use
(primary or secondary prevention), and patient wishes
might all be factors in the decision about whether to
continue ASA therapy.
Family physicians play an important role in advising
patients on the use of ASA, as shown by the nding
that 62.0% of patients took ASA for primary prevention
upon the advice of their family physicians. Patients
are also responsible for initiating ASA use, with 26.4%
starting ASA by themselves. As such, educating both
physicians and patients on the risks and benefits of
ASA therapy is necessary. Evidence from the Berger
et al
5
and Baigent et al
7
meta-analyses and available
brief summaries of the current evidence
28,29
can aid
in discussing the risks and benefits of ASA ther-
apy. Acetylsalicylic acid has been shown to be benefi-
cial in preventing recurrent cardiovascular events and
death in patients with known cardiovascular disease.
3,4
Only 62.5% of patients with cardiovascular disease in
our study were taking ASA regularly. This nding is
consistent with other studies that demonstrate sub-
optimal rates of ASA use for secondary cardiovascu-
lar prevention.
1,2,30,31
While it is possible that some
patients might have been taking alternative antiplate-
let or antithrombotic agents or have had substantial
adverse events when taking ASA, it is likely that some
patients who might benefit from ASA therapy are not
receiving it. Such patients should be identified and
advised about the benefit of ASA therapy in secondary
cardiovascular prevention.
Our study reveals that patient beliefs regarding the
benefits of ASA therapy appear to differ, depending on
whether one takes ASA or not. Those who used ASA
were more likely to believe that the potential benefits
of ASA therapy outweighed the potential risks, while
those who did not use ASA were unsure of the benefit-
risk ratio of ASA therapy. Irrespective of using ASA or
not, very few respondents believed that the potential
risks of ASA therapy outweighed the potential benefits.
Patient beliefs might be influenced by direct-to-con-
sumer advertising, encounters with health care pro-
viders, or previous experiences with ASA. It is unclear
whether a patient’s belief and knowledge leads to ASA
use or if ASA use influences the patient’s belief about
the benefits of ASA therapy.
Limitations
Our study has several limitations. To be included
in the study, patients had to visit their family
physicians and, therefore, might have a different risk
of developing cardiovascular disease and exhibit a
different rate of ASA use than the general population.
In addition, patients from the 2 family clinics might
not be representative of family medicine clinics in
Alberta or Canada. All responses were self-reported
and were not validated with pharmacy or medical
records; however, previous literature suggests that
patients are able to accurately recall their medica-
tions
32
and serious cardiovascular conditions.
33
The
lack of detailed patient medical data on the question-
naire did not permit us to calculate individual patient
cardiovascular risks and determine whether patients
at higher cardiovascular risk were more likely to be
taking ASA. Furthermore, for those patients with
known cardiovascular disease who were not tak-
ing ASA, it was not possible to determine whether
they were using other antiplatelet agents or other
antithrombotic agents or if they had contraindica-
tions to ASA therapy.
VOL 59: JANUARY JANVIER 2013
|
Canadian Family Physician Le Médecin de famille canadien
61
Family practice patients’ use of acetylsalicylic acid for cardiovascular disease prevention |
Research
Conclusion
Many family practice patients take ASA to prevent future
cardiovascular events and more patients take ASA for pri-
mary prevention than for secondary prevention. Although
most patients appear to initiate the use of ASA upon the
advice of their family physicians, about one-quarter start
taking ASA themselves for primary prevention. Educating
both family physicians and patients about the potential
benefits and risks of ASA therapy might result in fewer
patients using ASA for primary cardiovascular prevention
and more patients using ASA for secondary cardiovascu-
lar prevention. Patients’ beliefs regarding the benefits of
ASA therapy appear to differ depending on whether they
are ASA users or not, with users believing that the bene-
fits outweigh the risks and nonusers being unsure of the
benefits and risks. The paucity of research on ASA use in
the primary care setting in Canada highlights the need for
a nationwide study to ascertain the use of ASA therapy in
the general population.
Dr Kolber is Associate Professor in the Department of Family Medicine at
the University of Alberta in Edmonton. Dr Sharif is Assistant Professor in
the Division of Emergency Medicine at the Schulich School of Medicine and
Dentistry at the University of Western Ontario in London. Mrs Marceau
is a nurse practitioner at the Peace River Primary Care Network in Alberta.
Ms Szafran is Associate Director of Research in the Department of Family
Medicine at the University of Alberta.
Contributors
Dr Kolber conceptualized the study and was involved in the development of
the study design and survey questionnaire, ethics application, study imple-
mentation, interpretation of study findings, and manuscript preparation. Dr
Sharif coordinated the study at the urban site, performed data entry, partici-
pated in the interpretation of the study findings, and reviewed the manuscript.
Mrs Marceau coordinated the study at the rural site, performed data entry,
and reviewed the manuscript. Ms Szafran was involved in the development of
the study design, ethics application, data analysis, interpretation of study find-
ings, and manuscript preparation.
Competing interests
None declared
Correspondence
Dr Michael Kolber, Department of Family Medicine, 1706 College Plaza,
University of Alberta, Edmonton, AB T6G 2C8; telephone 780 248-2058;
fax 780 492-2593; e-mail mkolber@ualberta.ca
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... 9 In addition, low-dose Aspirin reduced vascular inflammation in mice, decreased macrophage foam cell content and increased the stability of atherosclerotic plaque. 10 Thus, low ASA doses are commonly employed for primary and secondary prevention of thrombosis against cardiovascular disease (CVD). [10][11][12] But, the potential benefits are offset by potential harms of bleeding when ASA is employed as antithrombotic drug for primary CVD prevention. ...
... 10 Thus, low ASA doses are commonly employed for primary and secondary prevention of thrombosis against cardiovascular disease (CVD). [10][11][12] But, the potential benefits are offset by potential harms of bleeding when ASA is employed as antithrombotic drug for primary CVD prevention. 13 On the contrary, when ASA is used in patients previously suffering for an acute ischemic event (secondary prevention), the benefits outweigh the potential harms. ...
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... Future studies might also benefit from more detailed insights into patient and provider perceptions regarding aspirin benefits. The combined observations that aspirin is generally overutilized in low-CVD-risk groups and underutilized in high-CVD-risk groups, 18,21 as well as consistent indications that physician advice to use aspirin is highly motivating for patients, 8,38,39 highlight the need for better clinical tools to optimize aspirin utilization in primary prevention settings. The typical primary care environment, however, lacks convenient means to identify a given patient's synchronization with the USPSTF aspirin guidelines. ...
... It had to be assumed that the primary intent of regular aspirin use for cases in this study was for CVD prevention, which may be reasonable, given that CVD prevention is by far the most common reason cited by regular aspirin users in other contemporary studies. 39,46 However, this is important to confirm in medical records data, and future research should consider complementary patient interviews to validate the reason for aspirin use, as well as a greater number of chart audits conducted by experienced primary care physicians that can identify other possible, indirectly documented reasons for aspirin use (eg, extensive family history of CVD, chronic pain issues, temporary use due to specific medical procedures). Other study limitations involved the racial/ethnic homogeneity of the target population that restricts generalizability. ...
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Aspirin is commonly used for the primary prevention of cardiovascular disease (CVD) in the US. Previous research has observed significant levels of inappropriate aspirin use for primary CVD prevention in some European populations, but the degree to which aspirin is overutilized in the US remains unknown. This study examined the association between regular aspirin use and demographic/clinical factors in a population-based sample of adults without a clinical indication for aspirin for primary prevention. A cross-sectional analysis was performed using 2010-2012 data from individuals aged 30-79 years in the Marshfield Epidemiologic Study Area (WI, USA). Regular aspirin users included those who took aspirin at least every other day. There were 16,922 individuals who were not clinically indicated for aspirin therapy for primary CVD prevention. Of these, 19% were regular aspirin users. In the final adjusted model, participants who were older, male, lived in northern Wisconsin, had more frequent medical visits, and had greater body mass index had significantly higher odds of regular aspirin use (P<0.001 for all). Race/ethnicity, health insurance, smoking, blood pressure, and lipid levels had negligible influence on aspirin use. A sensitivity analysis found a significant interaction between age and number of medical visits, indicating progressively more aspirin use in older age groups who visited their provider frequently. There was evidence of aspirin overutilization in this US population without CVD. Older age and more frequent provider visits were the strongest predictors of inappropriate aspirin use. Obesity was the only significant clinical factor, suggesting misalignment between perceived aspirin benefits and cardiovascular risks in this subgroup of patients. Prospective studies that examine cardiac and bleeding events associated with regular aspirin use among obese samples (without CVD) are needed to refine clinical guidelines in this area.
... Clinicians should be encouraged that when they make recommendations to patients about aspirin use, they are highly influential on patient behavior. [3,[29][30][31] ...
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Recent trials suggest that aspirin for primary prevention may do more harm than good for some, including adults over 70 years of age. We sought to assess how primary care providers (PCPs) use aspirin for the primary prevention in older patients and to identify barriers to use according to recent guidelines, which recommend against routine use in patients over age 70. We surveyed PCPs about whether they would recommend aspirin in clinical vignettes of a 75-year-old patient with a 10-year atherosclerotic cardiovascular disease risk of 25%. We also queried perceived difficulty following guideline recommendations, as well as perceived barriers and facilitators. We obtained responses from 372 PCPs (47.9% response). In the patient vignette, 45.4% of clinicians recommended aspirin use, which did not vary by whether the patient was using aspirin initially (p = 0.21); 41.7% believed aspirin was beneficial. Perceived barriers to guideline-based aspirin use included concern about patients being upset (41.6%), possible malpractice claims (25.0%), and not having a strategy for discussing aspirin use (24.5%). The estimated adjusted probability of rating the guideline as “hard to follow” was higher in clinicians who believed aspirin was beneficial (29.4% vs. 8.0%; p < 0.001) and who worried the patient would be upset if told to stop aspirin (26.7% vs. 12.5%; p = 0.001). Internists vary considerably in their recommendations for aspirin use for primary prevention in older patients. A high proportion of PCPs continue to believe aspirin is beneficial in this setting. These results can inform de-implementation efforts to optimize evidence-based aspirin use.
... A cross-sectional survey conducted in 2009-2010 of patients at family practices in Alberta found that 40% of respondents took ASA. 1 Of those, roughly 41% took ASA for primary CVD prevention, most of whom stated it was based on advice from their health care provider. These findings are similar to the results of a national survey in the United States in 2012, where 52% of respondents aged 45 to 75 years reported taking ASA. 2 ASA is recommended in patients with established CVD (i.e., secondary prevention). ...
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... Our study findings were very similar to a Canadian study conducted in 2009-2010 in 2 family medicine clinics in Alberta, where among patients taking aspirin for CVD, 53.1% were using it for primary and 46.9% for secondary prevention (a difference of about 3-4% from our results) [47]. Furthermore, they had more males than females, older patients in the secondary prevention group, more patients in the primary prevention group initiating aspirin on their own, and majority of patients believing that benefits of aspirin outweigh its risks. ...
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... (A primer prevenció fogalmának megítélése külön dolgozat témáját képviseli.) Ugyanakkor az irodalomban fellelhető adatokhoz [7] hasonlóan a napi rutinban gyakran tapasztaljuk, hogy korábbi cardiovascularis eseményen át nem esett betegek is kapnak ASA-készítményt. Mivel az ilyen készítményekkel kezelt betegek zömében az idősebb, mozgásszervi betegségekben is szenvedő betegek közül kerülnek ki, az acetilszalicilsavalapú terápiát igen gyakran egyéb NSAID-készítményekkel együtt alkalmazzuk. ...
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Full-text available
To evaluate the benefits and harms of low dose aspirin in people with diabetes and no cardiovascular disease. Meta-analysis of randomised controlled trials. Medline (1966-November 2008), the Cochrane central register of controlled trials (Cochrane Library 2008;issue 4), and reference lists of retrieved articles. Review methods Randomised trials of aspirin compared with placebo or no aspirin in people with diabetes and no pre-existing cardiovascular disease were eligible for inclusion. Data on major cardiovascular events (death from cardiovascular causes, non-fatal myocardial infarction, non-fatal stroke, and all cause mortality) were extracted and pooled with a random effect model. Results are reported as relative risks with 95% confidence intervals. Of 157 studies in the literature searches, six were eligible (10 117 participants). When aspirin was compared with placebo there was no statistically significant reduction in the risk of major cardiovascular events (five studies, 9584 participants; relative risk 0.90, 95% confidence interval 0.81 to 1.00), cardiovascular mortality (four studies, n=8557, 0.94; 0.72 to 1.23), or all cause mortality (four studies, n=8557; 0.93, 0.82 to 1.05). Significant heterogeneity was found in the analysis for myocardial infarction (I(2)=62.2%; P=0.02) and stroke (I(2)=52.5%; P=0.08). Aspirin significantly reduced the risk of myocardial infarction in men (0.57, 0.34 to 0.94) but not in women (1.08, 0.71 to 1.65; P for interaction=0.056). Evidence relating to harms was inconsistent. A clear benefit of aspirin in the primary prevention of major cardiovascular events in people with diabetes remains unproved. Sex may be an important effect modifier. Toxicity is to be explored further.
Article
The Physicians' Health Study is a randomized, double-blind, placebo-controlled trial designed to determine whether low-dose aspirin (325 mg every other day) decreases cardiovascular mortality and whether beta carotene reduces the incidence of cancer. The aspirin component was terminated earlier than scheduled, and the preliminary findings were published. We now present detailed analyses of the cardiovascular component for 22,071 participants, at an average follow-up time of 60.2 months. There was a 44 percent reduction in the risk of myocardial infarction (relative risk, 0.56; 95 percent confidence interval, 0.45 to 0.70; P < 0.00001) in the aspirin group (254.8 per 100,000 per year as compared with 439.7 in the placebo group). A slightly increased risk of stroke among those taking aspirin was not statistically significant; this trend was observed primarily in the subgroup with hemorrhagic stroke (relative risk, 2.14; 95 percent confidence interval, 0.96 to 4.77; P = 0.06). No reduction in mortality from all cardiovascular causes was associated with aspirin (relative risk, 0.96; 95 percent confidence interval, 0.60 to 1.54). Further analyses showed that the reduction in the risk of myocardial infarction was apparent only among those who were 50 years of age and older. The benefit was present at all levels of cholesterol, but appeared greatest at low levels. The relative risk of ulcer in the aspirin group was 1.22 (169 in the aspirin group as compared with 138 in the placebo group; 95 percent confidence interval, 0.98 to 1.53; P = 0.08), and the relative risk of requiring a blood transfusion was 1.71. This trial of aspirin for the primary prevention of cardiovascular disease demonstrates a conclusive reduction in the risk of myocardial infarction, but the evidence concerning stroke and total cardiovascular deaths remains inconclusive because of the inadequate numbers of physicians with these end points.
Article
Aspirin is known to be effective in treatment of acute myocardial infarction and in secondary prevention of cardiovascular disease in both men and women (BMJ 2002;324:71–86). In addition, trials have indicated that low-dose aspirin is effective in primary prevention of myocardial infarction in men without a significant effect on ischemic stroke. There are, however, few data with respect to aspirin use and primary prevention of cardiovascular disease in women. In this article, 39,876 women 45 years of age or older and considered healthy at study entrance were randomized to receive 100 mg of aspirin or placebo on alternate days. They were followed up for 10 years for a first major cardiovascular event (death from cardiovascular cause, nonfatal myocardial infarction, or nonfatal stroke). In follow-up, there were 477 major cardiovascular events in the aspirin group and 522 in the placebo group. This 9% reduction in risk with aspirin was not significant (relative risk [RR], 0.91; 95% confidence interval [CI], 0.80–1.03; P = .13). There was a 17% reduction in risk of stroke in the aspirin patients vs those treated with placebo (RR, 0.83; 95% CI, 0.69–0.99; P = .04). This resulted from a 24% reduction in risk of ischemic stroke (RR, 0.76; 95% CI, 0.63–0.93; P = .009). There was a nonsignificant increase in risk of hemorrhagic stroke in the aspirin group (RR, 1.24; 95% CI, 0.82–1.87; P = .31). Aspirin had no significant effect on risk of fatal or nonfatal myocardial infarction. Gastrointestinal bleeding leading to transfusion was more frequent in the aspirin than in the placebo group (RR, 1.40; 95% CI, 1.07–1.83; P = .02). Subgroup analysis indicated that the most consistent benefit for aspirin occurred in women 65 years of age or older at study entry. In these women, the risk of major cardiovascular events was reduced by 26% in the aspirin group (P = .008), and the risk of ischemic stroke was reduced by 30% (P = .05). Also, myocardial infarction was decreased by aspirin use (P = .04).
Article
PurposePatients' self-reported drug exposure is subjected to memory errors and different sources of bias. Utilization of prescription records is impaired with non-compliance and over-the-counter (OTC) drug utilization. This study compared patients' self-report (PS) to physician's prescriptions of cardiovascular drugs (CVDs).Methods The PGRx database is constituted by networks of specialized centers that recruited cases of 15 different diseases including myocardial infarction (MI) cases, and a network of general practitioners recruiting a pool of potential referents. For MI cases and referents, data on all drug utilization within the 2 years preceding the index date were obtained from PS and from physician's report of their prescriptions (PP). Patients' reports were obtained using a structured telephone interview complemented with an interview guide containing names of diseases and pictures of drug packages. Comparisons were made on exposure to each class of CVDs, for different time-windows, 2 months, 3–12 months and 13–24 months prior to the index date.ResultsThe concordance between physician and patient report was assessed on 2702 patient–physician pairs. Agreement was excellent overall (κ = 0.83, 95% confidence interval (CI): 0.81–0.85). Prevalences of exposure were very close between PS and PP for all classes of prescription CVDs.Conclusion Using a standardized and systematic collection of information on drug exposure directly from patients appeared to provide similar information to using physician prescription records over a 2-year recall period. Copyright © 2010 John Wiley & Sons, Ltd.
Article
Concomitant use of antiplatelet agents and proton-pump inhibitors (PPIs) has been recommended in patients with a history of gastrointestinal (GI) hemorrhage. However, recent studies have reported that PPIs may alter clopidogrel's pharmacokinetics and potentially lead to an increased risk of recurrent adverse cardiovascular (CV) events. Using Taiwan's 2000-2006 National Health Insurance database, this population-based retrospective cohort study assessed CV and GI events in patients who had a prior history of GI bleeding and had been prescribed ongoing antiplatelet therapy after acute coronary syndrome (ACS) discharge. We identified 3,580 ACS patients and categorized them into (1) those taking clopidogrel alone, (2) those taking clopidogrel plus PPIs, and (3) those taking aspirin plus PPIs. Cox proportional hazards models were used to assess the association between the use of antiplatelet therapies and CV/GI events. The clopidogrel only group and the clopidogrel plus PPI group were found to be at lower risk for GI events than the aspirin plus PPI group [adjusted hazard ratio (HR) 0.23 (95% confidence interval; CI 0.14-0.36) and HR 0.70 (0.52-0.96), respectively]. However, while the clopidogrel only group had a lower risk of CV events than the aspirin plus PPI group [HR 0.57 (0.38-0.84)], the clopidogrel plus PPI group had a significantly higher CV risk than the aspirin plus PPI group [HR 1.59 (1.18-2.13)]. Our findings suggest that although the use of clopidogrel plus PPIs provides GI benefits, with this treatment, there is an increased CV risk among patients with a history of GI bleeding.
Article
Patients' self-reported drug exposure is subjected to memory errors and different sources of bias. Utilization of prescription records is impaired with non-compliance and over-the-counter (OTC) drug utilization. This study compared patients' self-report (PS) to physician's prescriptions of cardiovascular drugs (CVDs). The PGRx database is constituted by networks of specialized centers that recruited cases of 15 different diseases including myocardial infarction (MI) cases, and a network of general practitioners recruiting a pool of potential referents. For MI cases and referents, data on all drug utilization within the 2 years preceding the index date were obtained from PS and from physician's report of their prescriptions (PP). Patients' reports were obtained using a structured telephone interview complemented with an interview guide containing names of diseases and pictures of drug packages. Comparisons were made on exposure to each class of CVDs, for different time-windows, 2 months, 3-12 months and 13-24 months prior to the index date. The concordance between physician and patient report was assessed on 2702 patient-physician pairs. Agreement was excellent overall (kappa = 0.83, 95% confidence interval (CI): 0.81-0.85). Prevalences of exposure were very close between PS and PP for all classes of prescription CVDs. Using a standardized and systematic collection of information on drug exposure directly from patients appeared to provide similar information to using physician prescription records over a 2-year recall period.