Narrative review of health-related quality of life and its predictors among patients with coronary heart disease

Authors

  • Imran Muhammad BSN (Honours) RN,

    Staff Nurse
    1. Ward B65 (General Medicine/Cardiology), Khoo Teck Phuat Hospital, Singapore
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  • Hong-Gu He PhD RN,

    Assistant Professor
    1. Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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  • Yanika Kowitlawakul PhD RN,

    Assistant Professor
    1. Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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  • Wenru Wang PhD RN

    Assistant Professor, Corresponding author
    1. Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
    • Correspondence: Wenru Wang, Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Level 2, Clinical Research Centre, Block MD 11,10 Medical Drive, Singapore 117597. Email: nurww@nus.edu.sg

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Abstract

This paper summarizes the empirical evidence concerning health-related quality of life (HRQoL) of patients with coronary heart disease (CHD) and attempts to identify its significant predictors. A systematic search of the literature from 2002 to 2012 was conducted using seven electronic databases (CINAHL, ScienceDirect, Medline, Scopus, PsycINFO, PubMed and Web of Science) using the search terms ‘HRQoL’. ‘CHD’, ‘social support’, ‘depression’, ‘anxiety’, ‘psychosocial factors’, ‘sociodemographic factors’, ‘clinical factors’ and ‘predictors’. A total of 1052 studies were retrieved, of which 24 articles were included in this review. Previous studies have consistently demonstrated the negative impact of CHD on HRQoL, citing three major types of predictive factors: sociodemographic, clinical and psychosocial factors. Studies have also highlighted the advantageous use of HRQoL as a gauge for treatment satisfaction and efficacy. There are, however, few studies that collectively investigate the relationship among concepts such as HRQoL, anxiety and depression, social support, and sociodemographic and clinical factors in relation to CHD. This review highlights the need to conduct further study on HRQoL of patients with CHD in the Asian context. Such research will promote patient-centric care and improved patient satisfaction through incorporation of the concept of HRQoL into clinical practice.

Introduction

Coronary heart disease (CHD) continues to be one of the leading causes of morbidity and mortality among adults worldwide despite reductions in morbidity and mortality rates due to improvements in treatment and preventive measures.[1-3] Given the prolonged life expectancy resulting from these improvements, patients have to contend with CHD symptoms such as chest pain and breathlessness, as well as complex treatment regimens, over a longer period of time, producing negative effects on both physical and mental well-being.[4]

Given the far-reaching effects of CHD on physical, social and psychological aspects of the patient's life, health-related quality of life (HRQoL) is seen as a suitable outcome measure to guide clinical practice.[4] HRQoL is a subjective evaluation by the individual regarding the effects of the illness and its accompanying treatment on the individual's life.[4] It is a multifaceted concept including physical, psychological and social well-being.[5] This concept serves well as a gauge for treatment efficacy and considers factors that are possibly of more importance to patients, such as psychological and social well-being.[5, 6] With the rise in the incidence of cardiac risk factors like chronic diseases (e.g. hypertension, diabetes), obesity and an ageing population, many countries will face an increased number of patients with CHD in the near future.[7] The aim of this review is therefore to summarize the evidence of the impact of CHD on HRQoL and its significant predictors. Through this review, research gaps will be identified to conduct future studies. This will assist health-care professionals in their efforts to better manage CHD and reduce dependency on the health-care system.[8, 9] Failure to do so will lead to a society burdened with increased costs of care for these patients.[7]

Methods

Search strategy

A literature search was conducted using seven electronic databases: CINAHL, ScienceDirect, Medline, Scopus, PsycINFO, PubMed and Web of Science. The keywords ‘HRQoL’, ‘CHD’, ‘social support’, ‘depression’, ‘anxiety’, ‘sociodemographic factors’, ‘clinical factors’, ‘psychosocial factors’ and ‘predictors’ were used in various combinations while conducting the search. The reference and citation lists of selected articles were also screened for potentially relevant articles. Articles were included if they were (i) in English; (ii) peer-reviewed; (iii) primary research reports or systematic reviews; and (iv) published between 2002 and 2012. Articles were excluded (i) if they solely discussed HRQoL of patients with congestive heart failure, chronic kidney disease, stroke or other chronic diseases, or (ii) if they were editorial articles.

A total of 1052 studies were retrieved from seven databases, and 24 studies, including 23 quantitative research reports and one systematic review, that met the inclusion criteria were reviewed. HRQoL was considered as the outcome variable for all these articles. Study participants were diagnosed with CHD, including acute myocardial infarction (AMI) or angina. The articles discussed the effects of CHD on patients' HRQoL and the significant predictors of these effects. The studies were conducted with measurements being taken at various time points, providing a perspective on changes in HRQoL over time. The samples in the reviewed articles had a mean age range of 45–68 years old, ranged in size from 63 to 37 386 and consisted predominantly of male Caucasians. The characteristics of the reviewed articles are summarized in Table 1.

Table 1. Characteristics of reviewed studies evaluating health-related quality of life and its associated factors among patients with coronary heart disease
Authors and year ofCountryAimsResearch designSample (n)Outcome measuresInstrumentsKey findings
  1. AMI, acute myocardial infarction; BDI, Beck Depression Inventory; CABG, coronary artery bypass graft; CAD, coronary artery disease; CCI, Charlson Comorbidity Index; CCOQ, Competence and Control Orientations Questionnaire; CDC, Centers for Disease Control; CDD-R, Chest Discomfort Diary—Revised; CESD, Centre for Epidemiologic Studies (Depression); CHD, Coronary Heart Disease; CLLS, Cantril Ladder of Life Satisfaction; CR, cardiac rehabilitation; CVD, cardiovascular disease; ENRICHD, Enhancing Recovery in Coronary Heart Disease; GHQ-28, General Health Questionnaire-28; HADS, Hospital Anxiety and Depression Scale; HFFISS, Hollingshead Four-Factor Index of Social Status; HRQoL, health-related quality of life; IPQ, Illness Perception Questionnaire; KSQ, Kellner Symptom Questionnaire; MCS, Mental Component Summary; MI, myocardial infarction; MIDAS, Myocardial Infarction Dimension Assessment Scale; MOS-SSS, Medical Outcome Studies—Social Support Survey; MSPSS, Multidimensional Scale of Perceived Social Support; NEO PI-R, NEO Personality Inventory—Revised; PCS, Physical Component Summary; PRIME-MD, Primary Care Evaluation of Mental Disorders; QoL, quality of life; RQ-S, Rose Questionnaire; SAQ, Seattle Angina Questionnaire; SD, sociodemographic; SF-12, Short Form-12 Health Survey; SF-36, Short Form-36 Health Survey; SORT-R, Slosson Oral Reading Test—Revised; SS, social support; STAI, State-Trait Anxiety Inventory.
Kimble et al., 2011[10]USAExamine impact of symptoms on QoLDescriptive correlational study

134

Mean age: 64

HRQoL

Symptom cluster: fatigue, chest pain, dyspnea

SD factors

Clinical Factors

SF-36

HFFISS

SAQ

CCI

RQ-S

SORT-R

CDD-R

Predictors of poorer HRQoL:
  • Greater angina, fatigue and dyspnea frequency
  • Lower social status
  • Greater comorbidity
  • Younger adults (poorer mental health)
Ford et al., 2008[11]USA

To examine differences in HRQoL between CHD and healthy population

To examine the effect of the interaction between CHD and diabetes on HRQoL

Comparative correlational study

50 573

Mean age: 45.8

HRQoL

SD factors

Clinical factors

CDC HRQOL-4

Patients with CHD:

  • Increased number of physically and mentally unhealthy days and activity-limited days

Predictors of poorer QoL:

  • CHD and diabetes
  • Women
Chan et al., 2005[12]Hong KongTo examine the QoL of patients following hospital admission with CAD in Hong Kong and use of CRPretest–posttest study

182

Mean age: 62

HRQoL

SD factors

CR uptake

SF-36 (Chinese)

25% of 182 attended CR

Significant improvement in HRQoL after 6 months

No significant group differences in HRQoL between CR attendees and absentees

Sherman et al., 2003[13]USATo examine the baseline HRQoL of postmenopausal women with heart disease enrolled in the Estrogen Replacement and Atherosclerosis trialDescriptive correlational study

301

Mean age 65.5

HRQoL

Psychosocial and physical functioning

Emotional well-being

Sleep quality

SF-36

MOS-SSS

CESD

Social support was positively associated with better functioning for all measured outcomes

Social strain was negatively associated with HRQL functioning

Rantanen et al., 2008[14]Finland

To describe and compare the HRQoL of patients and their significant others

To identify factors associated with HRQoL one month after CABG

Comparative correlational study

270 CABG patients

240 significant others

HRQoL15-dimensional generic instrument

CABG patients had poorer QoL compared with general population

Significant others had QoL similar to general population

Lau-Walker et al., 2009[15]UKTo examine the association between CHD patients' illness beliefs and their quality of life three years after hospital dischargeDescriptive, correlational, longitudinal study253

HRQoL

Perception of symptoms

Sense of control

SF-36

IPQ

CHD patients' perception of their symptoms and sense of control at time of discharge were significantly associated with their quality of life three years after discharge
Norris et al., 2010[16]CanadaTo examine whether persistent sex differences in the health status of patients with CAD can be attributed to social factorsComparative correlational study

2403

1950 male; mean age: 64

453 female; mean age: 66

Gender roles

SD factors

Clinical factors

Depression

HRQoL

SAQ

HADS

Factors affecting HRQoL:

  • Gender role
  • Angina frequency
  • Physical limitations

Women reported higher anxiety levels

Shibeshi et al., 2007[17]USATo examine the effect of anxiety on mortality and nonfatal MI in patients with CADDescriptive, correlational, longitudinal study

516

Mean age: 68

Anxiety

HRQoL

KSQIncreased anxiety score, increased risk of MI or death among CAD
Škodová et al., 2011[18]SlovakiaTo explore the potential of psychological well-being and socioeconomic position as predictors of HRQoL in patients with CAD

Single-cohort prospective longitudinal study

Baseline, 1 year, 2 year

106

Mean age: 57

Psychosocial factors

HRQoL

Psychological well-being

Vital exhaustion

Maastricht interview (vital exhaustion)

GHQ-28

SF-36

Psychosocial factors (psychological well-being, vital exhaustion) are more important predictors of change in HRQoL compared with some objective medical indicators (ejection fraction) among patients with CHD
Barry et al., 2006[19]USATo determine whether perceived SS predicted change in HRQoL, operationalized as change in mental health and physical functioning, 6 months after CABGDescriptive, correlational, longitudinal study (baseline, 6-month follow-up)

1072

Mean age: 67.2

QoL

Mental health

Physical functioning

SS

ENRICHD

Social Support Inventory

SF-36

Frequent instrumental support predicted positive change in mental health

Change scores were higher when participants had low pre-CABG mental health

Neither SS variable predicted change in physical functioning

Höfer et al., 2005[20]AustriaTo test a conceptual model of HRQoL in CAD using structural equation modellingDescriptive, correlational, longitudinal study (baseline, 1- and 3-month follow up)

432

Mean age: 65.9

HRQoL

SS

Anxiety and depression

Clinical status

SD data

SF-36

MacNew HD-HRQoL Questionnaire

HADS

STAI

CCOQ

Depression and anxiety symptoms exerted the most significant influence on HRQoL
Stafford et al., 2009[21]Australia

Investigate the impact of potentially modifiable illness beliefs about CAD on depressive symptomatology

Examined the association between these beliefs and HRQoL and SD variations in illness beliefs

Longitudinal study

193

Mean Age: 61

HRQoL

Psychosocial factors

SD factors

Illness perception

Neuroticism

IPQ

HADS

SF-36

MSPSS

NEO PI-R

Negative illness beliefs predictive of higher levels of depressive symptomatology

Positive illness perceptions predictive of better HRQoL

Older and less socially advantaged had more negative illness beliefs

Xie et al., 2008[22]USATo quantify the national impact of CHD on patient-reported health status in the noninstitutionalized population in the USADescriptive, comparative study

37 386

With CHD: 2091

Without CHD: 35 196

Random sample

Health status

HRQoL

SD factors

SF-12

EuroQoL/EQ-5D

Poorer HRQoL among CHD participants

Predictors:

  • Female
  • Aged 18–49
  • Black or Hispanic
Stafford et al., 2012[23]UK

To generate nationally representative HRQoL estimates for CVD and cardiac comorbidities

Assess differential impacts by socioeconomic position using data from the Health Survey for England

Simple descriptive study

Random sample

26 104

HRQoL

SD factors

Clinical factors

EuroQoL/EQ-5D

Doctor-diagnosed stroke, heart attack and angina were associated with the greatest decreases in EQ-5D

Reduction in EQ-5D associated with the condition/risk factor was greater for those occupying lower socioeconomic positions

Statistically significantly so for obesity, hypertension and diabetes

Soto et al., 2005[24]SpainTo determine the clinical and SD factors related to the physical and mental components of the HRQoL in coronary patientsSimple descriptive study

132

Mean age: 60.7

HRQoL

SD factors

Mental health

Clinical factors

Psychosocial factors

SF-36

GHQ-28

History of CHD and greater age increased the PCS of the HRQoL

No CHD history and lower age diminished the PCS score

Younger adults had lowest MCS score

Brink et al., 2005[25]SwedenTo determine the clinical and SD factors related to the physical and mental components of HRQoL in coronary patientsComparative descriptive study

33 women

65 men

HRQoL

Gender

Depression

Fatigue

SF-36

HADS

Somatic Health Complaints

Improvement in HRQoL at 1 year for all participants

Women reported better mental health; men demonstrated better physical health

Predictors of lower HRQoL: anxiety and depression

Lee, 2009[26]AustraliaTo establish via multiple regression analyses the determinants of physical and mental HRQoL 5 years post-CABGSimple descriptive, longitudinal study109

HRQoL

Dietary, physical activity and psychological well-being

SF-36

Allied Dunbar National Fitness Survey diet sheet

Physical activity/exercise sheet.

BDI

STAI

Anxiety and depressive symptoms are strongly implicated in determining PCS and MCS 5 years post-CABG using the SF-36
Baune et al., 2012[27]VariousSystematic review of the moderating influence of clinical and SD variables on the observed interrelationship between depressive disorders and CVDSystematic review

IHD

Depression

Treatment

HRQoL

Psychosocial factors

Literature search

Clinical characteristics of depression, such as severity of depression, number of episodes and duration of depression, might moderate the relationship between depression and CVD

Marital status, education and income are moderators of this relationship

Lindquist et al. 2003[28]USATo compare HRQoL including patient-perceived neurocognitive function at preoperative baseline and 3 months after CABG surgery.Comparative correlational study

405 men

269 women

CABG

HRQoL

SD factors

Clinical factors

SF-12

STAI

CESD

CLLS

Both male and female patients improved in physical, social and emotional functioning after CABG

Women's HRQoL scale scores remained less favorable than men's through 1 year after surgery

Norris et al., 2008[29]CanadaTo compare the HRQoL outcomes of men and womenPretest–posttest study

1872 men

522 women

CABG

HRQoL

SD factors

Clinical factors

SAQ

EuroQoL/EQ-5D

CESD

MOS-SSS

Women with CAD reported poorer HRQoL 1 year after coronary angiography compared with men
Thomson et al., 2012[4]UK

To assess differences in SS and QoL in patients and partners awaiting CABG

To examine whether patients' and partners' perceived SS predicted their own, as well as their partner's, QoL before CABG

Simple descriptive study84 dyads (patient and caregiver)

CHD

HRQoL

SS

SF-12

MOS-SSS

Patients with low informational/emotional support had poorer mental health
Christian et al., 2007[30]USATo evaluate predictors of HRQoL and determine the impact of a brief educational intervention on HRQoL 6 months post-hospitalizationPretest–posttest study

160

Mean age: 63

CHD

Women

HRQoL

Clinical status

Psychosocial status

Educational intervention

CCI

PRIME-MD

STAI

SF-36

Significant improvements in HRQoL from admission to 6 months post hospitalization.

Predictors:

  • Employed
  • Married
  • Physically active
  • Enrolled in CR
  • Not depressed

Intervention group had significantly less bodily pain at 6 months compared with usual care in a model

Wang et al., 2014[31]ChinaTo assess HRQoL and identify associated factors in hospitalized Chinese MI patientsSimple descriptive study

192

Mean age: 65

CHD

Clinical factors

SD factors

HRQoL

MIDAS

SF-36

HADS

Predictors of overall HRQoL:
  • Increased age
  • Anxiety and depression
  • Heart failure
  • Smoking
  • Hypertension
Failde et al., 2010[32]SpainTo determine the construct and criterion validity of the SF-12 in CAD patients with either AMI or angina in SpainSimple descriptive study

186

Mean age: 68.1

Clinical factors

SD factors

HRQoL

Mental health

SF-12

SF-36

GHQ-28

Female patients and those with low educational level, worse mental health, unstable angina, cardiovascular risk factors and comorbidity obtained a lower score in the SF-12

High correlations between SF-12 and SF-36 summary scores

Results

HRQoL among patients with CHD

Previous studies have highlighted poorer HRQoL among patients with CHD when compared with the healthy population, highlighting failure to return to premorbid status and the necessity to carefully manage these patients.[11, 15, 20, 21, 33] Lee and colleagues[34] explained that the negative impact of CHD on HRQoL resulted from persistent chest pain and fear of another attack. Thompson and Roebuck[33] further stated that overwhelming management plans and poor coping after the onset of CHD were among other factors that resulted in poor HRQoL. Boersma and colleagues[35] discussed how the impact of CHD on HRQoL results from emotional distress caused by the disruption of daily activities. Such emotional distress often manifests as anxiety and depression, which further impairs the individual's physical and mental well-being.[35] Patients with poor HRQoL often report poorer health status, accelerated disease progression and increased used of health-care services and assistance compared with healthier people with better HRQoL.[5, 27] Although the authors acknowledged the improvement that comes with learning to cope and increased acceptance of the disease, they emphasized the presence of low HRQoL scores, highlighting the necessity to carefully manage these patients.[27] Boersma and colleagues[35] warned that patients with poor HRQoL are at increased risk for cardiac-related mortality and chronic disabling conditions such as stroke. Christian and colleagues[30] went on to show the influence of CHD on the individual's physical, psychological and social experience, finding that variables such as sociodemographic, clinical and psychosocial factors mediated the effect of CHD on HRQoL and, as such, served as significant predictors of HRQoL among patients with CHD.

Measuring HRQoL

There are two types of instruments used to measure HRQoL: generic and disease-specific questionnaires. Generic instruments such as the Short Form Health Survey questionnaires (SF-36 and SF-12) cover a broad spectrum of quality-of-life components, which allows for comparison of health status across different diseases, severities, interventions and even cultures.[24, 32] Disease-specific questionnaires such as the Myocardial Infarction Dimension Assessment Scale (MIDAS) and Seattle Angina Questionnaire (SAQ) are more sensitive in measuring the impact of CHD on the participant's HRQoL.[36]

One study used SF-36 to measure HRQoL and found low HRQoL scores, highlighting the failure to return to premorbid status.[13] It reported lower Mental and Physical Component Summary scores among CHD patients compared with the healthy population.[13] The reliability of these findings was further supported when Wang and colleagues[31] used both a disease-specific instrument (MIDAS) and a generic questionnaire (SF-36), obtaining poor HRQoL scores from both instruments. Garster and colleagues[37] concluded that generic instruments were able to capture differences in HRQoL between populations with or without CHD. They went on to highlight that generic instruments allow for comparison between different disease populations and can assist with public policy decisions.[37]

Predictors of HRQoL among patients with CHD

Sociodemographic factors

Several studies have found age to be inversely related to HRQoL, with younger and middle-aged patients with CHD reporting poorer results in the mental health component of HRQoL as compared with the elderly (aged 65 years old and above).[11, 18, 25, 35] This could be due to how the onset of disease affects the level of productivity of young working individuals.[11] Moreover, the experience that comes with age probably assists elderly patients to better deal with the challenges resulting from CHD.[10, 22] However, better physical functioning was reported among younger participants compared with the elderly, so CHD is viewed to be less debilitating in the younger population.[27, 31, 35] This phenomenon would be useful to investigate in an ageing society.

CHD has been found to be more prevalent among the male population.[15, 37, 38] However, female patients with CHD tend to be older and medically worse off compared with male patients.[40] Current evidence shows female patients with CHD report poorer HRQoL compared with male patients even after controlling for clinical and psychosocial factors.[12, 14, 16, 22, 28, 34, 35] These studies attributed their findings to differences in clinical course between genders, with female patients reporting atypical symptoms, being poorer candidates for coronary artery bypass graft (CABG) treatments and having different coping mechanisms. Another plausible reason for such a difference would be the increased risk of depression experienced by female patients with CHD, which could further impact HRQoL compared with their male counterparts.[11, 37] Burell and Granlund[40] added that low self-esteem, exhaustion and stressors related to family demands have also been found to lower the HRQoL and delay recovery process among female patients with CHD.

Xie and colleagues,[22] investigating HRQoL among different sociodemographic groups, highlighted lower HRQoL among minority black and Hispanic CHD patients compared with Caucasians. Cepeda-Valery and colleagues[41] added that African American CHD patients reported higher incidence of angina, poorer physical functioning and poorer HRQoL compared with Caucasian Americans. The researchers attributed this difference to the inequality that exists in access to health care in America. It appears that the negative impact of CHD on HRQoL extends beyond the Western population, with three Chinese-based studies reporting poor HRQoL among Chinese patients with CHD.[9, 31, 34] In Singapore, variations in CHD have been observed between the major ethnic groups, with Indian patients having the highest rates of cardiac-related mortality compared with Malays and Chinese.[42, 43]

There appears to be sufficient evidence that socioeconomic status (SES), as measured by education, income and occupation, is a major predictive factor of HRQoL.[13, 22, 23, 44, 45] Farin and Meder[45] found that individuals with higher SES generally reported higher HRQoL and better health outcomes when compared with individuals with lower SES. Such a phenomenon is probably due to the increased accessibility and affordability of health-care services for higher-SES individuals, which ultimately improves their health outcomes.[22, 23] Barbareschi and colleagues[44] added that low-SES individuals possessed limited resources to promote well-being and had poor treatment adherence, poorer physiological functioning, and higher psychosocial stress, resulting in accelerated disease progression and lower HRQoL. It is crucial that socially disadvantaged individuals be provided with the necessary assistance to cope with CHD and improve HRQoL. The aforementioned point was emphasized by Škodová and colleagues,[18] who attributed the lack of significant difference in HRQoL among different SES levels in Slovakia to compulsory individual health-care coverage, which reduces social inequalities in access to health-care services.

Other studies account for the individual effects of education, occupation and income on HRQoL. In Spain, Failde and colleagues[32] reported a correlation between lower education and lower MCS score using the SF-36. Apart from the possible social inequality in Spain, the authors explained that lack of knowledge translated to poor understanding of disease and treatment plans, which led to stress, reducing HRQoL among these patients.[32] On the other hand, employment predicted better HRQoL as it gave participants a sense of purpose and importance, indirectly improving HRQoL.[12, 13, 31]

Clinical factors

Cardiac-related comorbidities such as hypertension and diabetes were strong predictors of poor HRQoL among patients with CHD.[13, 23, 25] Sherman and colleagues[13] explained that the chronic nature of diabetes and its associated complications, such as peripheral vascular disease and diabetic retinopathy, can contribute to reducing the HRQoL of patients with CHD. Other cardiac risk factors such as smoking have also been found to be predictors of poor HRQoL of patients with CHD.[31, 46]

The type of diagnosis has also been found to be a predictor of HRQoL, with patients diagnosed with unstable angina reporting poorer HRQoL compared with AMI patients.[10, 16, 24, 32] Kimble and colleagues[10] attributed these findings to the symptoms of pain, fatigue and dyspnoea that are strongly associated with unstable angina. These symptoms were found to negatively impact individuals' physical and emotional functioning, which in turn reduced their HRQoL through self-imposed limitations on daily routines to avoid episodes of chest pains.[10]

Patients receiving revascularization therapies such as CABG and percutaneous coronary intervention (PCI) reported better HRQoL compared with patients receiving conservative management or medical therapy.[13, 28, 47-49] Even among patients receiving PCI, differences have been noted in HRQoL outcomes, with patients receiving drug-eluting stents reporting better HRQoL compared with those receiving bare metal stents, with reduced restenosis rate, improved health outcome and reduced uncertainty of a recurrent attack.[39]

Another predictive factor would be the severity of the CHD, with triple-vessel disease patients reporting increased symptom burden, poorer health outcomes and poorer HRQoL when compared with patients with single-vessel disease.[47] Apart from the severity of disease, chronicity of CHD has been seen as an influencing factor in HRQoL. Newly diagnosed AMI patients experienced comparatively lower HRQoL than patients with history of CHD.[34]

Psychosocial factors

Anxiety and depression among patients with CHD

Several studies found anxiety and depression to be strong independent predictive factors of poor HRQoL among patients with CHD.[13, 20, 27, 37, 50] Previous studies indicated that about 17–27% of patients with CHD experienced major depression, whereas 20–45% demonstrated depressive symptoms, with female AMI patients facing a higher risk of depression.[30, 50, 51] On the other hand, two-thirds of patients with CHD were reported to experience anxiety post-diagnosis.[52] Antoniou and Dokoutsidou[53] explained that the loss of self-esteem, stress, inability to fulfill one's roles (social, familial, professional), uncertainty and distorted self-image are known to contribute to the onset of anxiety and depression after AMI and angioplasty. Their onset is also accelerated by the absence of coping mechanisms, lack of social support, increased stress and sociodemographic factors like gender.[5, 50]

Anxiety and depression differ in terms of their influence on HRQoL. Höfer and colleagues[20] explained that HRQoL, in terms of general health perception and physical functioning, is directly affected by anxiety and indirectly by depression. Two studies reported that participants experiencing depression faced a higher risk of suffering from a recurring heart attack,[5, 39] whereas another revealed an association between high anxiety scores and increased risk of death or non-fatal myocardial infarction.[17]

Myers and colleagues[6] associated the above findings with reduced engagement in secondary preventive behaviours crucial in delaying disease progression. They went on to explain that reduced engagement in health behaviours can be caused by medical mistrust, lack of support and motivation, or a fatalistic attitude.[6] Lee added that depressive symptoms increase distress levels and impair work and personal and social functioning, which affects personal and psychological well-being and HRQoL.[26] Although the majority of patients with CHD adapt over time, nearly one-fifth of patients fail to adjust to the emotional strain.[30]

Social support

Social support has been found to be a predictor of HRQoL in several studies.[25, 54] Previous studies reported that presence of emotional support exerted a positive influence on HRQoL in patients with CHD, with widowed participants experiencing lower HRQoL compared with married individuals.[4, 19, 35] In Hong Kong, an Asian culture with a strong concept of filial piety and family values, the presence of children as a form of social support contributed to better health outcomes among patients with CHD.[12] However, Barry and colleagues[19] argued that emotional support was an insignificant predictor of HRQoL 6 months post-CABG, as compared with instrumental support, which positively predicted improved mental health. This could be due to the greater importance placed by CABG patients on receiving assistance with activities of daily living during the course of recovery.[19]

Other negative predictors of HRQoL included social strain, high levels of uncertainty, poor patient–physician relationship, anger and cynicism.[36, 45, 48] Lau-Walker and colleagues[15] highlighted poor sense of control post-CABG surgery as a predictor of poorer HRQoL, and Stafford and colleagues[50] reported poor HRQoL outcomes among patients with CHD with negative illness perception. All these factors eventually lead to stress and anxiety among patients with CHD, resulting in poor HRQoL.[15, 45, 48]

Discussion

According to current evidence, patients with CHD tend to report lower HRQoL compared with the healthy population.[37] There is no universal definition of HRQoL[4]; however, authors agree that it involves the subjective evaluation of the impact of the disease and treatment on the patient's lifestyle, often encompassing the physical, social, psychological and environmental aspects.[49] CHD influences HRQoL by affecting aspects of patients' lifestyle and alters their health perception in the process.[15] The effect can be caused by pain from a single episode of AMI or the persistent and often disruptive pain of unstable angina.[32] Moreover, the stress induced by the experience of being diagnosed with CHD, the increased risk for a recurrent attack and the overwhelming lifestyle changes post-diagnosis often alter patients' perceptions of HRQoL for the worse.[11, 36] Severity of disease and even the number of cardiac comorbidities also negatively affect HRQoL.[36]

Current evidence shows that the impact of CHD on HRQoL can be amplified or reduced depending on several factors, which can serve as predictors of HRQoL.[22] Gender has been reported to be a predictor, with female patients reporting poorer HRQoL; these findings are often attributed to poor coping mechanisms and altered role perception.[16, 29] Lower income level, resulting in reduced access to health care and inability to cope with rising health-care costs, can delay the recovery process and can be viewed as another predictor of worse impact of CHD on HRQoL.[23] However, this might not be entirely applicable in settings where there is sufficient health-care assistance provided.[45] Psychological morbidities such as anxiety and depression that occur before or after diagnosis of CHD have been found to increase the risk of recurrent AMI, delay recovery process and reduce medication compliance.[5, 6] Lack of social support also worsens the impact of CHD on HRQoL in view of the absence of a spouse or a reliable source of support to help patients meet their various lifestyle needs and to cope with the stress related to CHD management.[12, 19]

This review has several implications for nursing practice. Nurses conducting cardiac rehabilitation could consider tailoring programmes towards elderly patients in an attempt to improve physical functioning in view of their poorer physical health.[18] The inclusion of cognitive restructuring can improve self-esteem and reduce psychosocial stressors among younger outpatients with CHD.[40] In addition, nurses must get support from spouses and caregivers in the cardiac rehabilitation process. In addition, this review supports the suggestion that nurses caring for patients with CHD should use screening tools in routine clinical management.[35, 36] These screening tools could assist nurses in identifying patients with poor HRQoL who might require alternative medical interventions to improve treatment adherence, clinical outcomes and HRQoL.[38, 39]

Although much is known on HRQoL among patients with CHD and its significant predictors, research findings were limited in terms of generalizability, as studies predominantly investigated Western populations. There is limited knowledge of Asian CHD outpatient populations with regard to their perceptions of what supports or undermines their HRQoL, the extent of anxiety and depression post-CHD and the influence of social support on HRQoL. There might be variation in the impact of CHD on HRQoL among different ethnic groups, which warrants attention given the presence of ethnic differences in CHD prevalence in Asian countries such as Singapore, where Indian residents face a higher risk of AMI compared with the Chinese and Malay populations.[42, 55] In addition to that, there are few studies that clearly investigate the relationships among concepts such as HRQoL, anxiety and depression, social support, and sociodemographic and clinical factors related to CHD.

Another underresearched area is whether multiple medications or polypharmacy can influence HRQoL of outpatients with CHD, given the numerous prescriptions that the majority of patients are required to adhere to in order to manage CHD and its associated comorbidities. There have also been reports of improvements in HRQoL among patients undergoing revascularization therapy.[19, 28, 47] However, there are few comparisons of HRQoL between patients who opt for only pharmacological treatments and patients who undergo PCI or CABG. This gap deserves more attention in order to enhance efforts to promote medication adherence and other treatment options. Another underresearched area is the efficacy of incorporating HRQoL measurement tools such as the SF-36 and SF-12 into clinical practice for evaluating care needs of patients.

Limitations and Conclusion

Although a careful literature search was conducted, the search strategy might not have found all the relevant published literature. The varying time-points used in the studies included in this review were not considered in the analysis. This might account for certain effects that were not identified in this current review. Nevertheless, this review meets its aim to summarize the empirical evidence concerning HRQoL of outpatients with CHD and to identify its significant predictors. Current evidence highlights the need to conduct a study to address research gaps and achieve better understanding of the HRQoL of CHD outpatients in Asian societies. Such efforts promote patient-centric care and improve patient satisfaction through incorporating the concept of HRQoL into clinical practice. This literature review is therefore the first step in moving towards providing holistic care to CHD outpatients in Asia.

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