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Quality of Life After Acute Myocardial Infarction Among Patients Treated at Sites With and Without On-site Availability of Angiography
Louise Pilote, MD, MPH, PhD;
Claude Lauzon, MD;
Thao Huynh, MD;
Danielle Dion, MD;
René Roux, MD;
Normand Racine, MD;
Suzanne Carignan, MD;
Jean G. Diodati, MD;
Claude Lévesque, MD;
François Charbonneau, MD;
Joël Pouliot, MD;
Lawrence Joseph, PhD;
Mark J. Eisenberg, MD, MPH
Arch Intern Med. 2002;162:553-559.
ABSTRACT
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Background Previous studies have compared the treatment and outcome of patients
with acute myocardial infarction (AMI) admitted at sites with and without
availability of angiography. Although mortality rates do not differ, it is
unknown if quality of life (QOL) and functional status differ.
Methods We measured QOL and functional status in patients with AMI treated within
Québec at 5 sites with (n = 253) and 5 sites without (n = 334) angiography.
Results At admission, clinical characteristics, complication rates, and baseline
measures of QOL and functional status were similar at sites with and without
angiography. During hospitalization, patients treated at sites with angiography
were more likely to undergo an invasive cardiac procedure than patients admitted
at sites without angiography (angiography, 63% vs 26%; percutaneous transluminal
coronary angioplasty, 33% vs 13%; and coronary artery bypass graft, 12% vs
5%). At 30 days and 6 months after AMI, QOL was slightly superior at sites
with angiography, but by 1 year, most measures of QOL were back to baseline
at both types of sites and were similar between the 2 groups. At 6 months,
most standard health-related QOL components were similar; only physical and
emotional role limitations were higher at sites with angiography. Return to
work occurred earlier (at 30 days, 23% vs 12%), and a lower proportion of
patients was readmitted for angina (within 1 year after AMI, 12% vs 18%) at
sites with angiography.
Conclusions In the early post-AMI period, the QOL of patients admitted at sites
with angiography was higher than that of patients admitted at sites without
angiography. However, by 1 year, the QOL and functional status of patients
was similar in both groups. Differences in QOL were greatest when differences
in treatment were greatest, lending support to a positive albeit small association
between an early invasive approach to post-AMI care and improved QOL.
INTRODUCTION
THE USE OF CARDIAC procedures has been shown in many studies to be related
to availability of procedures at the sites where patients are admitted for
acute myocardial infarction (AMI).1 Patients
treated at sites without cardiac procedures are likely to undergo fewer invasive
cardiac procedures, and their clinical outcomes are possibly inferior to those
of patients treated at sites with availability of cardiac procedures. In studies
that have compared the treatment and outcome of patients with AMI admitted
at sites with and without angiography, mortality did not differ between the
2 groups.2-8
However, these studies were limited by the lack of information on outcomes
other than mortality such as quality of life and functional status. Similarly,
several randomized clinical trials that have compared different approaches
to post-AMI care did not present data on outcomes related to quality of life.9-21
Thus, we conducted a prospective cohort study to measure quality of life after
AMI among patients admitted at sites with and without angiography within the
province of Québec.
PATIENTS AND METHODS
STUDY POPULATION
The study population consisted of patients who were treated in an acute
care facility (coronary care unit) for AMI diagnosed according to the World
Health Organization criteria.22 The same criteria
were used at both types of hospitals. Patients had to be admitted through
the emergency department. We excluded patients transferred from another hospital
for treatment of their index AMI or from another floor in the hospital. Any
patient able to read and understand French or English was eligible for the
study if he or she had sustained a Q- ornon–Q-wave AMI and had survived
up to 24 hours after hospital admission. A patient was excluded if he or she
was physically incapable of responding to a questionnaire (eg, if intubated)
or if unable to give informed consent. A total of 10 sites enrolled patients
in the study. The 5 sites without angiography were located at least 1 hour
by car away from a site with angiography. The choice of sites at this minimum
distance from sites with angiography was to avoid the possibility that sites
without angiography would have practice patterns similar to sites with angiography
because of geographic proximity.
For the present study, we wanted to estimate a difference between the
2 groups with high precision using a 95% confidence interval (CI).23 To make our original sample size requirement calculations,
we obtained estimates of the proportions from one of our studies in which
we measured quality of life after AMI in a randomly selected subgroup of American
and Canadian patients enrolled in the GUSTO-I study.24
Based on these calculations, it was our goal to enroll a total of 1000 patients.
An interim analysis, however, showed that our sample of 253 patients from
sites with and 334 patients from sites without angiography was sufficient
to obtain the precision required (total CI width of 10%) to estimate clinically
meaningful differences in patient scores of quality of life.
ASCERTAINMENT OF STUDY END POINTS
The primary end points were ascertained through chart review and patient
questionnaires at baseline, 30 days, 6 months, and 1 year after AMI. For baseline
measurements, patients were asked to remember their health state during the
month preceding their admission to the hospital for AMI. After completing
the baseline questionnaire during hospitalization, patients completed follow-up
mail surveys. Patients who did not respond to the mail survey were contacted
by telephone for an interview. Among patients lost to follow-up, vital status
at 1 year after AMI was obtained on all patients from a central death registry.
At each follow-up contact, details about all hospitalizations that occurred
since the last contact were obtained from the patient. For patients with an
emergency department visit, rehospitalization, or a cardiac procedure, a chart
review was performed by the study nurse.
Primary end points included quality of life, functional status, return
to work, and cardiac symptoms. The Short Form 36 (SF-36) questionnaire measures
health-related quality of life.25 This instrument
characterizes the respondent's health state, yielding a profile of scores
(0, poor to 100, optimal), one score for each health dimension. Differences
of 5 points are considered clinically relevant.26-27
The SF-36 questionnaire has been validated and shown to be reliable in French
and English.28 The visual analog scale adopted
from the Torrance Feeling Thermometer29 and
the EuroQol30 measure were used to elicit patient
ratings of their overall quality of life. Depression symptoms were measured
using the Beck Depression Inventory questionnaire.31
Functional status was assessed with the Duke Activity Status Index32 and the Katz activities of daily living scale,33 a single 4-level question about the effects of the
patient's health on overall functioning. Questions on bed days and reduced
activity days were taken from the National Center for Health Statistics.34 Disease-specific symptoms (angina and dyspnea) were
assessed with the Rose questionnaire.35 To
measure return to work, employment status was evaluated using the instrument
of the Study of Economics and Quality of Life, a substudy of the Bypass Angioplasty
Revascularization Investigation.36 These measures
include employment history over the preceding 6 months, annual income, days
lost from work due to illness, and need for domestic help. Finally, secondary
end points included readmission for a cardiac cause and all-cause mortality.
STATISTICAL ANALYSIS
First, patient characteristics and the different outcome measures were
compared between patients admitted at sites with and without angiography in
univariate analyses. Rates of noninvasive and invasive cardiac procedures
during hospitalization for the index AMI and over the year following discharge
and time to receipt of these cardiac procedures were also compared. Second,
multivariate analyses were performed to obtain adjusted comparisons of SF-36
quality of life measures between patients admitted at sites with and without
angiography. Specifically, the models included the following variables: age,
sex, education, depression score, history of angina and diabetes, peak creatine
kinase, type of AMI (Q wave or not, first or second episode, location), and
hospital course for index AMI (complicated by congestive heart failure, recurrent
infarct, and/or ischemia).
For these analyses, the dependent variable of the primary regression
model was health status represented by the various components of the SF-36
questionnaire. Model selection used Bayes factors as approximated by the Bayesian
information criterion.37 These models have
demonstrated better prediction properties on average than other model selection
algorithms such as backward or forward stepwise procedures.
RESULTS
DEMOGRAPHIC AND CLINICAL CHARACTERISTICS OF STUDY PARTICIPANTS
Between January 1997 and November 1998, 952 patients were approached
for study enrollment during their hospitalization for their index AMI. Of
these patients, 587 were enrolled in our study and observed for 1 year; 253
patients were treated at 5 sites with angiography (Montreal General Hospital,
Jewish General Hospital, Royal Victoria Hospital, Notre-Dame Hospital, and
Complèxe Hospitalier de La Sagamie) and 334 at 5 sites without angiography
(Centre Hospitalier de la Région de l'Amiante, Centre Hospitalier de
Val-D'Or, Hôpital Sainte-Croix de Drummondville, Centre Hospitalier
regional du Grand Portage, and Centre Hospitalier Beauce Etchemin). All sites
were in Montreal, Québec. Timing of enrollment was between 2 and 5
days after AMI and was the same at both types of site. Reasons for nonenrollment
included patient refusal (57%), feeling too sick (21%), death (11%), physician
refusal (2%), participation in another study (2%), and other reasons combined
(7%). Patients who refused to participate were older than study participants
(mean age, 69 vs 61 years), more likely to be female (37% vs 21%), and less
likely to have sustained a Q-wave infarct (43% vs 49%). Otherwise, they were
similar.
Patients at sites with and without angiography were similar but for
the following characteristics: patients at sites with angiography were more
likely to be male (83% vs 75%) and their level of education was higher (13
vs 9 years) (Table 1). Additionally,
prior AMI (23% vs 19%) and angina (30% vs 22%) were more common and creatinine
kinase level higher at sites with angiography.
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Table 1. Demographic and Clinical Characteristics of Study Patients
According to Site of Admission for Acute Myocardial Infarction*
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The proportion of patients who completed 1 year of follow-up was 84%
at sites with angiography and 91% at sites without angiography. Patients lost
to follow-up were more likely to have diabetes (25% vs 15%) and smoke (52%
vs 40%) and were less likely to have sustained recurrent ischemia (17% vs
22%) than those who completed the 1-year questionnaire. Otherwise they were
similar.
TREATMENT DIFFERENCES BETWEEN PATIENTS ADMITTED AT SITES WITH AND WITHOUT
CORONARY ANGIOGRAPHY
Whereas the use of cardiac medications after AMI was similar at the
2 types of sites, the use of invasive and noninvasive cardiac procedures differed
(Table 2). Overall, patients at
sites with angiography were more likely to undergo invasive procedures early
in the post-AMI period. The median time to angiography was 4 days at sites
with angiography and 17 days at sites without angiography. Although in-hospital
rates of angiography, angioplasty, and coronary artery bypass surgery were
greater at sites with angiography than at those without, the difference in
invasive procedure rates narrowed over time. In contrast, noninvasive procedures
were used less often at sites with angiography. By 1 year, more patients at
sites without angiography had undergone exercise treadmill testing (80% vs
65%) and twice as many had undergone thallium testing (47% vs 25%). Thus,
even though by 1 year the difference in use of noninvasive testing remained,
the difference in use of invasive testing and procedures decreased.
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Table 2. Use of Cardiac Medications and Invasive and Noninvasive Cardiac
Procedures by 1 Year After Acute Myocardial Infarction*
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Patients admitted at sites with angiography were more likely to be treated
by a cardiologist. The yearly AMI volume in the hospitals with angiography
was higher (212 vs 160 patients), and so was the number of hospital beds (555
vs 208). These hospitals were representative of other hospitals in the province.
HEALTH PERCEPTION AND EXPECTATIONS
At baseline, patients at sites with and without angiography seemed to
have a similar perception of their health status (Table 3). However, at 30 days after AMI, general health perception
on a scale of 0 (death) to 100 (perfect health) of patients at sites with
angiography tended to be superior to that of patients at sites without angiography.
Furthermore, 30% of patients at sites with angiography ranked their general
health perception as very good to excellent compared with 17% of patients
at sites without angiography. Also, at 30 days, patients at sites with angiography
ranked their physical ability higher. Except for the rating of general health,
which remained higher at sites with angiography, by 6 months and 1 year, general
health perception and expectations returned to a similar level between the
2 groups. Thus, health perceptions and expectations were superior among patients
treated at sites with angiography only in the early post-AMI period.
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Table 3. Unadjusted Measures of Health Perception and Functional Status
and Adjusted Odds Ratios or Differences in Health Perception and Functional
Status Between Patients With AMI Treated at Sites With and Without Angiography*
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FUNCTIONAL STATUS AND RETURN TO WORK
Physical activity did not differ between the 2 groups at baseline as
indicated by the Duke Activity Status Index (Table 3). Furthermore, measures at 6 months and 1 year did not differ
from measures at baseline, but measures at 30 days were equally lower in both
groups (data not shown).
At baseline, 43% of patients at both sites worked full-time (roughly
44 hours per week) or part-time, and a similar proportion of patients planned
to return to work (73% vs 76%). Over 75% of patients were the major income
earners. At 30 days, twice as many patients at sites with angiography had
gone back to work than patients at sites without angiography. However, by
6 months and 1 year, the proportion of patients back to work was similar at
both sites. Similarly, at 30 days both groups reduced their activities, but
patients at sites with angiography reported a lower number of days of reduced
activities. However, by 6 months and 1 year, the level of reduced activity
was back to baseline in both groups. Days in bed followed a similar trend.
QUALITY OF LIFE (SF-36)
For the outcome of health status at baseline, emotional role limitations
were ranked higher by patients at sites without angiography; otherwise, the
unadjusted and adjusted measures of SF-36 did not differ significantly between
patients in the 2 groups (Table 4).
But by 6 months, patients at sites with angiography scored higher on the subscale
of "role limitations–emotional" and also on "role limitations–physical."
However by 1 year, most subscales were back to baseline except for role limitations–emotional,
which was still scored higher by patients at sites with angiography. Thus,
although patients at sites without angiography started with higher scores
for role limitations–emotional, by 6 months and 1 year, patients treated
at sites with angiography exhibited higher scores for the subscales of role
limitations–emotional and role limitations–physical.
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Table 4. Unadjusted SF-36 Measures of Quality of Life and Adjusted
Differences in Quality of Life Between Patients With AMI Treated at Sites
With and Without Angiography*
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Furthermore, compared with baseline, the subscales of role limitations–emotional
and role limitations–physical indicated a deterioration at 1 year among
patients at sites without angiography but no notable differences among patients
at sites with angiography. For example, between baseline and 1 year after
AMI, the score for the subscale of role limitations–emotional declined
by 12.2 points, compared with an increase in 1 point for patients at sites
with angiography (difference, 13.2 points; 95% CI, 8.9-17.5). Similarly, the
score for the subscale of role limitations–physical declined by 10.1
points at sites without angiography compared with 3.8 points at sites with
angiography (difference, 6.4; 95% CI, 2.1-10.7). Of note, most SF-36 subscales
remained similar between the 2 groups throughout the study period, indicating
a minimal impact of AMI on quality of life as measured by SF-36.
CARDIAC SYMPTOMS AND HOSPITAL READMISSIONS FOR AMI-RELATED COMPLICATIONS
A higher proportion of patients at sites without angiography were readmitted
to the hospital after AMI than occurred at sites with angiography (52% vs
33%) (Table 5). Several of these
patients were readmitted to undergo the cardiac procedure they were waiting
for. Nevertheless, readmission for a cardiac complication occurred more frequently
among patients at sites without angiography (23% vs 19%), and the difference
was attributed to a higher readmission rate for angina (18% vs 12%). However,
the proportions of patients who reported post-AMI angina and dyspnea were
similar. For example, at baseline, the prevalence of angina was 10% at sites
with angiography and 9% at sites without angiography, and for dyspnea, 49%
and 52%, respectively. At 1 year, the prevalence of angina was 7% and 7%,
respectively, and that of dyspnea, 37% and 33%, respectively (Table 3). Thus, even though the prevalence of angina reported by
patients did not differ between the 2 groups, more patients at sites without
angiography were readmitted for angina after index AMI. Finally, even if the
sample size is too small to make any strong conclusions about mortality, the
mortality was higher at sites with angiography, probably reflecting baseline
differences in severity and possibly procedure-related complications.
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Table 5. One-Year Cumulative Incidence of Hospital Readmissions and
Mortality
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COMMENT
In this study, we observed modest differences in quality of life that
were more marked when differences in cardiac procedure use were greatest.
At sites without angiography, the treatment approach tended to be that of
risk stratification, with a higher use of noninvasive diagnostic testing and
a lower use early in the post-AMI period of invasive procedures. In contrast,
the approach at sites with angiography consisted of early use of angiography
and revascularization. As a result, the 2 different approaches seemed to affect
the speed of recovery. Patients at sites without angiography tended to have
a slower recovery as manifested by their inferior scores on some of the SF-36
scales at 6 months, greater number of days with limited activity, and slower
return to work. Furthermore, answers to questions about health perception
revealed that patients admitted at sites without angiography perceived their
health to be inferior to that of patients at sites with angiography. Finally,
even though symptoms of angina did not differ between the 2 groups, patients
admitted at sites without angiography had more readmissions for angina after
AMI. But overall, the magnitude of the differences was small, and by 1 year
after AMI, patients admitted at sites with and without angiography had similar
quality of life and functional status.
The higher readmission rates for angina at sites without angiography
could be explained by the fact that coronary anatomy was known in fewer patients
at these sites. As a result, physicians may have been more likely to diagnose
a patient presenting with chest pain as having angina. Furthermore, return-to-work
differences could be attributed to physician attitudes rather than an effect
of revascularization procedures.
Several randomized clinical trials have compared different approaches
to post-MI care.9-18
In most of those studies, the principal outcome of interest was mortality,
and the different approaches did not result in any difference in mortality
rate. Studies have also compared the treatment of AMI in Canadian and American
patients.24, 38-43
Similarly, in these studies, the different approaches failed to result in
any differences in mortality.
Only few studies have looked at other outcomes such as functional status,
cardiac symptoms, and quality of life. In the SAVE study, Rouleau et al40 showed that Canadian patients had a higher rate of
activity-limiting angina than American patients (relative risk, 1.27; 95%
CI, 1.06-1.51). In the GUSTO study, Mark et al24
surveyed a random sample of Canadian and American patients and found that
Canadians rated quality of life lower than did Americans. However, similar
to our study, the differences were small. Additionally, findings of studies
on quality of life comparisons between American and Canadian patients after
AMI are limited because the results might be explained by cultural differences
rather than differences in care. The natural experiment in the present study
has allowed us to compare quality of life outcome in patients treated with
different rates of cardiac procedure within the same health care system.
In our study, the intensity of procedure use in this cohort of Canadian
patients was greater than expected. In fact, the proportion of patients who
underwent angiography during hospitalization at sites with angiography approached
that found in the US GUSTO-I study.44 In the
GUSTO study, depending on the region of the United States, between 52% and
81% of patients underwent this procedure, compared with 68% in the present
cohort. The use of revascularization procedures in the present cohort also
approached that of the GUSTO US participants. Furthermore, within 1 year,
patients at sites without angiography in our study had rates of revascularization
similar to that of patients admitted at sites with angiography. Thus, even
if previous studies have shown marked discrepancies in the treatment of Canadian
and American patients, there are groups of patients in Canada who receive
post-AMI care akin to that in the United States.
Finally, although a careful economic analysis was not performed, there
might be economic implications of this delay in resuming baseline level of
quality of life among patients treated more conservatively. First, patients
returned to work later after AMI, thus incurring loss of productivity. Second,
several patients had to wait in the hospital before transfer to another hospital
for an angiographic cardiac procedure. For patients who underwent angiography,
the length of stay was longer at sites without angiography (median stay, 19
days; 25th-75th percentiles, 12-30 days vs 8 days; 5-13 days). Third, many
patients were transferred and then readmitted, contributing to a prolonged
overall hospital stay after AMI. Finally, a high proportion of patients at
sites without angiography underwent noninvasive testing. Thus, the cost to
society of the risk stratification approach is not negligible, even though
it may appear reasonable since (1) fewer patients undergo potentially unnecessary
cardiac procedures, and (2) by 1 year, quality of life is similar with the
2 different approaches.
Several limitations to our study must be considered. First, recall bias
for baseline measurements is a potential problem, although recall is not likely
to differ between patients admitted at sites with and without angiography.
This study is one of the few to provide baseline measurements for quality
of life. Baseline measures are the most powerful predictors of long-term quality
of life, and this study provides multivariate analyses with adjustments for
baseline quality of life. Second, even though this cohort consisted of a consecutive
series of patients with AMI, patients who died early were excluded, and several
eligible patients refused enrollment. But because the excluded patients and
patients who refused enrollment had similar characteristics at sites with
and without angiography, our findings are probably generalizable to all patients
with AMI who survive the first 2 days after hospitalization. Finally, although
statistical adjustments were made for measured differences in demographic
and clinical characteristics, differences may have persisted. For example,
patients treated at sites without angiography were less likely to be treated
by a cardiologist, were treated at hospitals with smaller AMI volume, and
were more likely to live in rural areas.
In conclusion, in areas where access to angiography is limited, risk
stratification and selection of patients for invasive cardiac procedures results
in patient quality of life by 1 year after AMI similar to prompt performance
of invasive cardiac procedures. Differences in quality of life were greatest
when differences in treatment were greatest, lending support to a positive
albeit small association between an early invasive approach to post-AMI care
and improved quality of life.
AUTHOR INFORMATION
Accepted for publication July 17, 2001.
This study was supported by grant 961305-104 from the Fonds de la recherche
en santé du Québec, Montreal. Drs Pilote and Eisenberg are Research
Scholars of the Heart and Stroke Foundation of Canada, Ottawa, Ontario.
We wish to thank our participating patients; our project coordinators,
Karen Brown, MPH, and Maria Masi, MSc; our research nurses, Francine Ouimet,
RN, Brigitte Roberge, RN, Alyne Landry, RN, Carolyn Boudreault, RN, Andrée
Morisette, RN, Marcel Rodrigue, RN, Manon Lévesque, RN, Diane Therrien,
RN, Louise Patrie, RN, Marjolaine Roussel, RN, Cécile Dufour, RN, Eileen
Shalit, RN, Dominique Brassard, RN, and Marcel Rehel, RN; our technical staff,
Christine Beck, MSc, and Ewurabena Simpson, BSc; and our secretary, Barbara
Cont.
Corresponding author: Louise Pilote, MD, MPH, PhD, Division of Clinical
Epidemiology, Montreal General Hospital, 1650 Cedar Ave, Montreal, Québec,
Canada H3G 1A4 (e-mail: louise.pilote{at}musica.mcgill.ca).
From McGill University Health Centre (Drs Pilote, Huynh, Charbonneau,
and Joseph); Centre Hospitalier de la Région de l'Amiante (Dr Lauzon);
Centre Hospitalier Beauce Etchemin (Dr Dion); Hôpital Sainte-Croix de
Drummondville (Dr Roux); Université de Montréal (Drs Racine
and Diodati); Centre Hospitalier régional du Grand Portage (Dr Carignan);
Complèxe Hospitalier de La Sagamie (Dr Lévesque); Centre Hospitalier
de Val D'or (Dr Pouliot); and Jewish General Hospital (Dr Eisenberg), Montreal,
Québec.
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