Cardiovascular disease (CVD) is a global public health concern with an estimated 17.9 million deaths in 2016, accounting for 31% of all global deaths . It is estimated that 151,377 million disability-adjusted life years was lost due to CVD . CVD is a group of heart and blood vessels disorders, including acute coronary syndromes (ACS) known as a “heart attack” . Approximately 80% of ACS patients die within the first one hour before they are carried to the nearest hospital [3, 4]. Compared to the general population, ACS patients are more likely to have depression and confined mobility, resulting in lower health-related quality of life (HRQOL) , a measure of perceived health status and satisfaction in performing daily life activities .
Treatments for ACS is vital and should be provided urgently. The guidelines of European Society of Cardiology and European Association for Cardio-Thoracic Surgery recommended an invasive strategy for most of ACS patients . Percutaneous coronary intervention (PCI) is the second most frequently performed invasive intervention for ACS in the U.S after cardiac catheterization in 2019 . In PCI, a flexible thin tube is used to insert a stent into an artery to widen plague-build-up-narrowed blood vessels in the heart, an atherosclerosis. This non-surgical intervention is highly successful and causes few complications [7, 8, 9]. Optimal medical therapy (OMT), which includes antiplatelet agents, statins, β-blockers and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, is an initial and essential treatment that needed for ACS patients whether or not they receive PCI [10, 11].
Previous studies showed that PCI improve HRQOL among ACS patients [12, 13]. There were also few studies on this issue conducted in Vietnam where the population is aging quickly and CVD as the leading cause of deaths is accounting for 30% of total disability-adjusted life years [14, 15]. Although HRQOL is an important measure to assess clinical outcomes , data on HRQOL among ACS patients were limited in Vietnam. Therefore, this study was conducted to 1) evaluate HRQOL of ACS patients in Nhan Dan Gia Dinh Hospital, Ho Chi Minh City (HCMC), Vietnam, 2) determine whether HRQOL was different for those receiving both PCI/OMT compared to those receiving OMT alone 6 to 12 months after treatment, and 3) examine associations between HRQOL and potential correlates.
2. MATERIALS AND METHOD
Nhan Dan Gia Dinh Hospital is a public provincial hospital administrated by the Ho Chi Minh City Department of Health. The 1,500-bed hospital with modern-equipment, and experienced and high-skilled healthcare professionals, is capable for 4.000 outpatient-visits and 300 emergencies per day. This is a teaching hospital of the University of Medicine and Pharmacy at Ho Chi Minh City (http://bvndgiadinh.org.vn/home/about/).
A cross-sectional design was used to collect data from ACS patients at the Department of Interventional Cardiology, Nhan Dan Gia Dinh Hospital between March and May 2019. The hospital provided treatment for more than 750 ACS patients in 2018, of which 76% received PCI. A list of patients and their medical records were used to screen for participant’s eligibility. Patients who 1) were at least 18 years old; 2) diagnosed with ACS including unstable angina (UA)/non-ST elevation myocardial infarction (NSTEMI) or ST elevation myocardial infarction (STEMI); 3) had coronary angiography; and 4) underwent PCI plus OMT (PCI/OMT) or OMT alone for 6 to 12 months at the hospital. Those who were unable to answer the questions due to limited cognitive ability; had chronic coronary artery disease; or underwent the second invasive strategy were excluded from the study. Eligible patients were invited to participate in the study when they visited the hospital for medical check-up. The purpose of the study was explained, and information sheet was provided to the patients. Patients were required to return written consents if they agreed to participate.
Face-to-face interviews were conducted using a structured questionnaire. Demographic and socio-economic characteristics collected included gender, age, marital status, education level, place of residence, working status, household economic and health insurance. Age was grouped into <65 years or ≥65 years as patients aged ≥65 years suffer higher risk of mortality . Weight and height were measured using standard protocols . Body Mass Index (BMI) calculated by [weight (kg)]/ [height squared (m2)] was used to determine patients’ weight status. A patient was classified as normal weight (BMI<23) and overweight/obese (BMI ≥23) as suggested by World Health Organization for Asian population . Household economic was certified by the local authorities as poor and non-poor.
Lifestyle behaviours, including smoking, drinking alcohol, and being physically active, were self-reported. A patient was considered an active smoker if they smoked within the last 30 days. Non-smokers or those who stopped smoking within the last 30 days were grouped together. Similarly, those who drank at least one standard unit of alcohol per day or five units within the last 30 days were considered a drinker. In addition, a patient was considered active if they self-reported engaging in at least 30 minutes of moderate-vigorous physical activity in at least 5 days/week and within the last 30 days. These simple questions, adapted from STEPS instrument , were used to reduce the response burden due to reduced memory and cognitive capacity among aging populations .
Clinical records were used to determine patients’ comorbidity status. A patient was considered having a comorbidity if they had on their records at least one of these conditions: hypertension, dyslipidemia, diabetes, chronic kidney disease, chronic liver disease, and chronic lung disease. Other clinical data collected were history of myocardial infarction, history of brain stroke, family history of cardiovascular diseases, type of ACS (UA/NSTEMI or STEMI), duration of treatment in months, the number of damaged vessels, and Left Ventricular Ejection Fraction (LVEF) (<40%, 40-50%, >50%) .
HRQOL was assessed using EQ-5D-5L and EQ-VAS that were developed by the EuroQoL Group [22, 23, 24, 25]. The EQ-5D-5L covers five HRQOL dimensions including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has five response options representing for a health status and ranging from having no, slight, moderate, severe, or extreme problems. Vietnamese value sets was then used to convert a health status into health utility index score . EQ-VAS evaluates imaginable health status that ranges from 0 (worst condition) to 100 (best condition). EQ-5D-5L and EQ-VAS are not time-consuming and easy to use. Their validity and reliability have been tested in previous studies [27, 28, 29].
Data were entered using Epidata v3.1 and analysed using STATA v13. Frequency and percentage were calculated for categorical variables. Mean and standard deviation (SD) were generated for continuous variables. Descriptive statistics were presented for the whole sample and by treatment type (i.e. OMT vs. PCI/OMT). Differences in sample characteristics between two treatment types were tested using either Chi-squared/Fisher’s exact tests (for categorical variables) or two-sample t-tests (for continuous variables). These tests were also used to test associations between each HRQOL dimension and type of ACS treatment.
The outcomes were EQ-5D-5L and EQ-VAS scores which were analyzed separately using linear regressions. Two models were run for each outcome. Model 1 were to test bivariate associations between the outcomes and independent variables including types of ACS treatment, age group, gender, weight status, marital status, education level, employment status, smoking, drinking, co-morbidities, the number of damaged vessels and LVEF. Model 2 were multivariable models that tested associations of independent variables adjusting for the other covariates. Crude and adjusted regression coefficients with their 95% confidence interval were reported. A two-sided p-value of less than 0.05 was considered as statistical significance.
A total of 125 ACS patients were screened and 113 patients (90%) were agreed to participate in the study. Of these, 73 patients (65%) received PCI/OMT, and 40 patients (35%) received OMT alone. The mean age was 61 years (SD=11 years), ranging from 34 to 84 years. Table 1 shows sample characteristics. Majority of patients were <65 years old (57%), men (68%), overweight/obese (57%), and married (80%). About half completed senior high school (53%) and were not working (58%). Most lived inside HCMC (84%) and was non-poor (85%).
PCI: percutaneous coronary intervention; OMT: Optimal medical therapy; ACS: acute coronary syndromes; UA/NSTEMI: unstable angina/non-ST elevation myocardial infarction; STEMI: ST elevation myocardial infarction; LVEF: Left Ventricular Ejection Fraction; SD: Standard deviation.
* Co-morbidity was yes if patient had one of the following diseases including hypertension, dyslipidemia, diabetes, chronic kidney disease, chronic liver disease or chronic lung disease
The percentage of smoking and drinking in the sample were 15% and 11%, respectively. More than half of patients engaged in at least 30 minutes of moderate-vigorous physical activity in at least 5 days/week and within 30 days (55%). Most patients (87%) had at least one co-morbidity. The percentage of patients had a history of myocardial infarction and a history of brain stroke was 8% and 6%, respectively. About one in 10 patients had a family history of cardiovascular disease and half was UA/NSTEMI. Nearly half of patients had three damaged vessels (47%), following by two (29%) and one (24%). Three quarter of patients had LVEF >50%, 13% had LVEF 40-50%, and 14% had LVEF <40%. The average duration of treatment was 9.4 ± 2.3 months, ranging from 6 to 12 months. There were differences between PCI/OMT and OMT groups in working status (p=0.02), health insurance (p=0.02), the number of damaged vessels (p=0.02), and place of residence (p=0.05).
Table 2 shows that more than one-third of the patients reported having problems with usual activity (43%), pain/discomfort (40%), or anxiety/depression (33%). About one-fifth had problem with mobility. Percentage of patients having problem with self-care was small (7%). Mean scores for EQ-5D-5L utility index and EQ-VAS scores were 0.88 (SD=0.15) and 65.6 (SD=13.3), respectively. There was no statistically significant difference in five HRQOL dimensions between PCI/OMT and OMT groups.
PCI: percutaneous coronary intervention; OMT: Optimal medical therapy; SD: Standard deviation; Higher EQ-5D-5L utility index score represents better quality of life. Higher EQ-VAS score represents better health status.
Table 3 shows associations between EQ-5D-5L utility index and EQ-VAS scores with treatment groups and other variables. In the bivariate analysis with EQ-5D-5L utility index as an outcome, patients with overweight/obesity had 0.06 points (95%CI: 0.00, 0.11) higher than those normal weight; patients with senior high school had 0.09 points (95%CI: 0.04; 0.14) higher than those with junior high school; those smoking had 0.14 points (95%CI: -0.21; -0.07) lower than those without smoking; those who were active had 0.07 points (95CI%: 0.02; 0.13) higher than inactive ones; and those with three damaged vessels had 0.09 points (95%CI:-0.16; -0.03) lower than those with one damaged vessel.
PCI: percutaneous coronary intervention; OMT: Optimal medical therapy; ACS: acute coronary syndromes; UA/NSTEMI: unstable angina/non-ST elevation myocardial infarction; STEMI: ST elevation myocardial infarction; LVEF: Left Ventricular Ejection Fraction; Coef.: regression coefficient; 95%CI: 95% confidence interval
Model 1: crude bivariate model between each independent variable with EQ-5D-5L utility index and EQ-VAS scores.
Model 2: multivariable model included treatment group, age group, gender, weight status, marital status, educational level, place of residence, working status, household economic, health insurance, smoking status, drinking status, physical activity, co-morbidity, history of myocardial infarction, history of brain stroke, family history of cardiovascular diseases, type of ACS, duration of treatment in months, the number of damaged vessels, and LVEF.
Bivariate analysis with EQ-VAS score as an outcome showed that patients ≥65 years had 5.54 points (95%CI: -10.5; -0.62) lower than those <65 years. Those completing senior high school had 8.17 points (95CI%: 3.42; 12.92) higher than those with only junior high school. Patients with a job had 5.01 points (95%CI: 0.04; 9.98) higher than those unemployed. Those being active had 5.78 points (95%CI: 0.89; 10.67) higher than inactive ones. Patients with three damaged vessels had 8.76 points (95%CI: -14.82; -2.7) lower than those with one damaged vessel.
In multivariable analyses, weight status, physical activity and smoking were independently associated with EQ-5D-5L utility index. Overweight/obese patients had 0.06 points (95%CI: 0.00; 0.11) lower than non-overweight/obese patients; active patients had 0.07 points (95%CI: 0.02; 0.12) higher than inactive patients; and smokers had 0.15 points (95%CI: -0.23; -0.06) lower than non-smokers. However, only physical activity remained significantly associated with EQ-VAS score. Active patients had 5.59 points (95%CI: 0.43; 10.75) higher than inactive ones. Although EQ-5D-5L utility index was not different between PCI/OMT and OMT groups in the bivariate analysis, the PCI/OMT group had 0.07 points (95%CI: -0.1; -0.01) lower than the OMT group after controlling for other variables. Similar results were found for EQ-VAS score that was 6.86 points (95%CI: -13.16 to -0.56) lower for the PCI/OMT group compared to the OMT group after controlling for other variables.
The EQ-5D-5L utility index (0.88, SD=0.15) among ACS patients in this study was similar to that of the Vietnamese general population aged 35+ (0.89, SD=0.16), but EQ-VAS score (65.6, SD=13.3) was lower (86.4, SD=13.4) . Additionally, the percentages of ACS patients reporting a problem in five HRQOL domains were also higher than those of the Vietnamese general population aged 35+ including usual activities (43% vs. 28%), pain/discomfort (40% vs. 13%), anxiety/depression (33% vs. 18%), and mobility (22% vs. 7%), and self-care (7% vs. 4%) . This is expected because participants in this study were ACS patients and a half of whom were 65 years or older who may rate their EQ-VAS score worse . It is noted that EQ-VAS score is a one-item general patients’ perspective scale whereas EQ-5D-5L utility index reflects societal perspectives and addresses five dimensions of life.
For all HRQOL domains, no difference in percentages of self-reported problems between PCI/OMT and OMT groups was found. However, it seemed that PCI/OMT groups had lower HRQOL scores than OMT groups. It is important to point out that while the differences in HRQOL scores were statistically significant, they may not be clinically significant due to small effect. Given the cross-sectional nature of this study, it is also likely that patients with PCI/OMT had worse health status than those with OMT and therefore lower HRQOL before treatment . Studies with stronger designs found that PCI/OMT groups had better HRQOL than OMT groups 6-12 months after medical interventions, however, the difference was not found after 12 months [13, 33, 34]. Although the two medical interventions had been proved to be generally safe [7, 8, 9], there are reports on complications that might decrease HRQOL [35, 36]. For example, using antiplatelet agents in OMT can cause major bleeding by erosive gastritis  and that could affect HRQOL . Severe hemodynamic compromise or even death can occur during PCI procedure . Despite the potential complications, both PCI/OMT and OMT alone were found to provide similar benefits in reducing mortality rate and releasing angina .
In this study, overweight/obese patients had EQ-5D-5L utility index slightly higher, but no difference was observed in EQ-VAS score. The association between BMI and HRQOL was inconsistent, complex and could not be generalizable [39, 40]. A study showed that those with BMI>30 was 30% had lower HRQOL compared to those with BM<I25 adjusting for age, gender, education level, and social class . However, another study showed a non-linear association between BMI and HRQOL with interaction by age and gender in each domain of HRQOL . In sum, after adjusting for age, gender, co-morbidity, diet and physical activity, 70-year old normal weight men had 0.03 points higher than 70-year old obese men but women with higher weight had lower physical HRQOL .
The bivariate analysis showed positive association between education level and EQ-5D-5L utility index and EQ-VAS scores; however, the association was disappeared in the multivariable analysis that was consistent with a previous study conducted in Vietnamese general population , although studies conducted in other countries suggested people with higher education level had better HRQOL [41, 42]. The Vietnamese study explained that those who had higher education were more likely to suffer mental disorder that could reduce HRQOL . However, the association between education level with anxiety/depression domain of EQ-5D-5L was tested but no association was found in this study. It is also noted that higher education level is associated with higher income, better working status and better living condition thus result in better HRQOL . Working status is an important factor affecting quality of life because it shows one’s socio-economic status and types of activities and levels of functions [30, 42, 44, 45].
In this study, the percentage of smoking (15.0%) was lower compared to that reported in Global Adult Tobacco Survey in Vietnam (22.5%)  and the percentage of drinking (11.0%) was lower compared to that from a survey of rural district in the north of Vietnam (35%) . This may be due to the fact that our study population is ACS patients, many of whom were likely to minimize or even stop smoking and drinking after learning about their health condition . Although smoking and drinking increase the risk of morbidity and mortality , only smoking was associated with HRQOL in this study. Smoking has negative effects on health that has been clearly demonstrated in many populations . Smoking was also the only factor with a clinically meaningful effect on EQ-5D-5L utility index in this study . This is consistent with a previous longitudinal study reporting that smokers had HRQOL scores after PCI improved less than non-smokers .
Physical activity were another lifestyle factor with positive effect on HRQOL and this is consistent with previous findings . At least 30 minutes of moderate-vigorous physical activity in at least 5 days/week was beneficial to ACS patients although this is just a recommendation and should be conditional on individual health status . It is also worth noting that prevalence of insufficient physical activity was about 30% in general populations worldwide . As the Vietnamese population is quickly aging that increased age-related health problems , providing physical activity programs which are mostly unavailable at the moment, could be an effective way to improve HRQOL among older populations [55, 56].
This study has some limitations. Firstly, it is a cross-sectional study and therefore, causal relationship between HRQOL and other factors could not be assessed. Secondly, although some clinical characteristics were extracted from hospital records, other data were self-reported and therefore subject to recall bias. Another limitation was that angina’s characteristics such as severity, frequency or reliefs were not collected as the effectiveness of PCI significantly depends on angina’s characteristics . Lastly, data were collected in only one hospital and the sample was not large and therefore, generalizability of the findings may be limited.
In conclusion, differences in EQ-5D-5L utility index and EQ-VAS scores between PCI/OMT and OMT groups were not clinically meaningful. Smoking and physical activity are important factors influencing HRQOL among older Vietnamese populations. Interventions to improve lifestyle behaviours, particularly smoking and physical activity, are needed to improve HRQOL among ACS patients.