INTRODUCTION
Unstable angina (UA) is an irregular type of
angina
pectoris1 and a type of
acute
coronary syndrome
(ACS).2 Every year, in
the U.S, more than one million people are hospitalized due to unstable
angina and non–ST-segment elevation myocardial infarction
(UA/NSTEMI),3 and
incidence is increasing in many countries. The burden of UA is high, as
the first-year treatment cost of patients ($12,058 per patient) is
almost as high as that of myocardial infarction ($15,540 for each
survivor and $17,532 for each
death).4 Even with a
high cost intervention, health outcomes and long term prognosis may not
improve.
Previously, survival rates, complication rates, and functional
parameters were used as indicators of the efficacy of coronary artery
disease (CAD)
treatment.5 Over the
past years, however, the quality of life (QoL) of patients with chronic
diseases such as cardiovascular disease has also become an important
indicator of successful clinical
practice.6 Recently,
percutaneous coronary intervention (PCI) has emerged as a breakthrough
method for treating and predicting the outcomes of patients with CAD.
Given its superiority, PCI has become a frequently used
revascularization
strategy8 with some
evidence comparing QoL between patients with CAD and those receiving
this intervention.9-12QoL of patients with CAD may be evaluated using different instruments,
including the Seattle angina questionnaire
(SAQ)13 and the
physical activity
score,14 which are
specific to coronary diseases. Others, such as the 36-item short form
(SF-36),15 the
Nottingham health profile
(NHP)16, and the
Swedish quality of life survey
(SWED-QUAL)17 give a
more generic assessment and allow comparisons with non-CAD populations.
SAQ scores have been shown to predict 1-year mortality and ACS among
outpatients with coronary disease, and might play a crucial part in
stratifying the risk of such
patients18. A previous
study of 65 patients receiving PCI found that QoL measured with the
SF-36 improved significantly over time in six out of the eight domains
and all other domains showed an increase at 3-month follow-up. Moreover,
all five domains of SAQ improved significantly; however, the angina
stability score at 3-month follow-up was lower than the baseline
value.19 A 2008 study
comparing PCI and optimal medical therapy alone showed remarkable
improvements in health outcomes during the follow-up period in the PCI
group but these disappeared after 36
months.20
These studies suggest mixed results for PCI on quality of life in
patients in developed countries, but little is known about this area of
research in developing countries, including Vietnam. As Vietnam moves
into the epidemiological transition and experiences a growing burden of
non-communicable disease (NCD), research on the optimal treatments for
conditions such as Angina, and rapid implementation of best practice
from high-income countries, is essential to prepare the Vietnamese
health system for better management of the growing epidemic of NCDs.
This study aimed to compare QoL among patients with unstable angina
after PCI and examine factors associated with QoL improvement after PCI.
Our study adopts Lawton’s theoretical
framework21(see Fig. 1 ), which is regarded as appropriately for explaining
factors associated with patients’ QoL after myocardial infarction. On
theoretical grounds, Lawton distinguishes four domains of QoL:
‘Behavioral competence’, which includes physical health, daily
activities, cognitive functioning and social behaviour; ‘Objective
environment’, including material possessions, social support, and
network; ‘Domain-specific perceived QoL’, the degree of satisfaction
with all important (life) domains, such as social functioning, leisure
activities, living accommodation, and income; and ‘Psychological
well-being’, the weighted evaluated level of a person’s competence and
perceived quality in all domains of contemporary life. Lawton recommends
a hierarchical reference with ‘behavioral competence’ and ‘perceived
quality of life’ as central domains, ‘environment’ as a prerequisite or
catalyst, and ‘psychological well-being’ as the ultimate
outcome.22 These
behavioral competencies are the aspects of functioning that are strongly
influenced by illness. Given the scope of this study as well as the
complex nature of the intervention delivered to our participants, this
theoretical model for our study is adapted and presented as hereinafter.