- Open Access
Quality of life in patients with coronary heart disease-I: Assessment tools
© Thompson and Yu; licensee BioMed Central Ltd. 2003
Received: 29 July 2003
Accepted: 10 September 2003
Published: 10 September 2003
Health-related quality of life (HRQL) assessment is an important measure of the impact of the disease, effect of treatment and other variables affecting people's lives. The review focused on the assessment of HRQL in patient with coronary heart disease (CHD) by appropriate tools. Although no consensus exists about the precise definition of HRQL, a plethora of instruments have been developed to assess it. Two broad types – generic and disease-specific – have been developed but there is some debate about their relative merits. There is a wide selection of instruments available but choice should be based on a careful consideration of an instrument's psychometric properties, the breadth and depth with which it addresses relevant health domains and the specific clinical or research purpose for which it is intended.
There has been a rapid and significant growth in the measurement of quality of life as an indicator of health outcome in patients with coronary heart disease (CHD). In the clinical course of CHD, there are many aspects where patients' quality of life may be affect which include symptoms of angina and heart failure, limited exercise capacity of the aforementioned symptoms, the physical debility caused, and psychological stress associated with the chronic stress. Modern treatments nowadays focus not only on improving life expectancy, symptoms and functional status, but also quality of life. Thus, an improvement in health-related quality of life (HRQL) is considered to be important as a primary outcome and in the determination of therapeutic benefit [1–3]. This article will provide an overall view of how to assess HRQL, and the tools available for patients with CHD.
Health-related quality of life
Despite the widespread use of the phrase, there is no consensus on the definition of the concept of HRQL, though definitions usually refer to physical, emotional and social well-being. HRQL is a distinct construct which refers to the impact that health conditions and their symptoms have on an individual's quality of life, and, in the context of healthcare, the term HRQL is preferred over quality of life because the focus is on health. It provides a common benchmark against which can be measured the impact of different experiences and treatments for the same condition or the impact of different treatments across different conditions . As a consequence, HRQL instruments have evolved in order to assess the impact of disease, effect of treatment and other variables affecting people's lives. They provide an assessment of the patient's experience of his or her health problems in areas such as physical function, emotional function, social function, role performance, pain and fatigue. Thus, HRQL can be defined as health status and viewed as a continuum of increasingly complex patient outcomes: biological/physiological factors, symptoms, functioning, general health perceptions and overall wellbeing or quality of life .
While healthcare professionals may be more interested in changes in objective physical measures, patients (and family members/carers) equally interested in a therapy that changes their symptoms, physical function and social roles. HRQL instruments measure the effects of treatment on aspects where patients are continuously concerning about. Because these instruments describe or characterize what the patient has experienced as a result of healthcare, they are useful and important supplements to traditional physiological or biological measures of health status .
Measurement of health-related quality of life
When measuring HRQL it is important that the instrument selected measures the health dimensions relevant to that particular set of patients [5, 6]. For instance, an instrument intended for use with patients after myocardial infarction (MI) should take into account the individual's responses to living with the disease, in terms of recreational, occupational, social, personal and sexual relationships, as well as the acute and chronic physical consequences of the disease . This is because when someone becomes ill almost all aspects of his or her life may be affected .
Validated instruments available for the assessment of health-related quality of life in patients with coronary heart disease.
Sickness Impact Profile
Seattle Angina Questionnaire
Medical Outcomes Study 36-Item Short
Quality of Life after Myocardial
Form Health Survey (SF-36)
Infarction questionnaire / MacNew questionnaire
Minnesota Living with Heart Failure questionnaire
Myocardial Infarction Dimensional Assessment Scale (MIDAS)
Cardiovascular Limitations and Symptoms Profile (CLASP)
When selecting a HRQL instrument, an important issue is how well it will perform in providing the most appropriate and required information . Thus, its psychometric properties (reliability and validity) should be examined [6, 8]. Reliability of an instrument is normally assessed in two ways: internal consistency and test-retest reliability. The former is an estimate of homogeneity of items measuring a specific health domain and is normally measured using Cronbach's alpha coefficient. The closer the coefficient is to 1, the greater the homogeneity between the items and, therefore, the greater the confidence that can be attributed that items relate to the domain under investigation. However, caution should be noted as alpha coefficients of >0.95 can mean that several of the items are in fact measuring the same thing [6, 10].
Test-retest reliability is a measure of an instrument's ability to produce data that are consistent or stable over time. It is normally determined using Cohen's Kappa or Pearson's or Spearman's correlation coefficient. Normally, levels in excess of 0.6 indicate an adequate test-retest reliability [6, 10].
Validity refers to the ability of a measure to quantify the item or dimension it is supposed to measure. It should have various forms of validity. Criterion validity refers to comparable results using other instruments measuring the same variable. Content validity is the appropriateness of items to the purpose of the instrument. Face validity represents being consistent with current knowledge and expert opinion. Construct validity is the ability of the instrument to be sensitive to different levels of quality of life in a variety of patient groups. Discriminative validity is the instrument's ability to detect changes in the observed variable without provoking a 'floor' or 'ceiling' effect that reflects an inability to detect clinically significant changes at the lower or higher spectrum of quality of life.
Both reliability and validity are not one-time-only attributes: they need to be re-established when the instrument is used in a different population or culture.
A number of generic instruments are commonly used in research and clinical evaluation in populations with CHD. The two most commonly used ones are the Sickness Impact Profile  and the Medical Outcomes Study 36-Item Short Form Health Survey .
Sickness Impact Profile (SIP)
The SIP  comprises 136 items relating to 12 'domains' of health (mobility, ambulation, domestic affairs, social interaction, behaviour, communication, recreation, eating, work, sleep, emotions and self-care). It is thus a broadly applicable instrument that measures a variety of health outcomes, including serial changes in wellbeing over time. The SIP can be interviewer- or self-administered and offers a comprehensive means of assessing wellbeing, but its relatively long length can be a disadvantage. However, it has been recommended as an appropriate generic measure in angina and MI patients [12, 13].
Medical Outcomes Study 36-Item Short Form Health Survey (SF-36)
The SF-36  comprises 36 items covering eight 'domains' (physical functioning, social functioning, physical impairment, emotional impairment, emotions, vitality, pain and global health). The SF-36 is a self-administered instrument which takes about 15 minutes to complete. Abbreviated forms, the SF-12 and now the SF-8, are also available and widely used, taking even less time to complete. The SF-36 has been used in angina, MI  and heart failure. However, although some reports suggest that the SF-12 is preferable to the SF-36 because of its brevity and acceptability to CHD patients , some studies in acute MI patients have found that the SF-12 scores obscure important distinctions between domains . In patients with recent MI, SF-36 has been shown to be a sensitive tool for detecting improvement of HRQL after active intervention [18–20].
A number of instruments have been designed to examine specifically the impact of angina, MI or heart failure on quality of life. Examples include the Seattle Angina Questionnaire , the Quality of Life after Myocardial Infarction [22–27] questionnaire (now called the MacNew  questionnaire) and Minnesota Living with Heart Failure  questionnaire.
Seattle Angina Questionnaire (SAQ)
The SAQ  is a psychometrically solid disease-specific instrument designed to assess the functional status of patients with angina. It comprises 19 questions that quantify five clinically relevant domains: physical limitation, anginal stability, anginal frequency, treatment satisfaction and disease perception/quality of life. It is often used as a HRQL instrument because seven of its 19 items relate to emotional health.
Quality of Life after Myocardial Infarction (QLMI/MacNew) questionnaire
The original version of the QLMI  was designed to be interview-administered and developed to evaluate the effectiveness of a comprehensive cardiac rehabilitation programme. A slightly modified 26-item self-administered version has been used [23, 24]. This questionnaire has been validated.[24, 25] More recently, an improved 27-item version of the instrument, the MacNew heart disease questionnaire (sometimes known as the QLMI-2) has been reported . A good deal of research is being conducted with this instrument and reference data for users is now available .
Minnesota Living with Heart Failure (MLHF) questionnaire
The MLHF  comprises 21 items with a range of responses from no, very little to very much to produce a range of scores from 0 (no disability) to 105 (maximal disability) in relation to signs and symptoms typical of heart failure, physical activity, social interaction, sexual activity, work and emotions. The reliability and validity of the MLHF are sound and it appears sensitive to changes in treatment, and thus the instrument is used extensively in studies of heart failure.
Recent reviews have critically examined commonly used generic and disease-specific HRQL instruments in patients with CHD [12, 13, 29–32]. All the generic instruments studied appeared to have measurement idiosyncrasies. For example, it was recommended  that the SIP should only be used to obtain total domain scores and should not be separated into its component scales. The SF-36 appears to achieve the best results, having fewer floor or ceiling effects, good internal consistency and a high test-retest reliability .
In terms of disease-specific measures, the SAQ and MLHF seem to perform well. For instance, in angina the SAQ appears more sensitive and easier to use by both patients and investigators than was the SF-36 . The MacNew (QLMI-2) has had mixed reviews [30, 32], though it role has been affirmed in patients with myocardial infarction and angina. Its role in patients with heart failure also showed preliminary promise.
Myocardial Infarction Dimensional Assessment Scale (MIDAS)
The MIDAS  is an interviewer- or self-administered questionnaire than comprises 35 items covering seven areas of health status (physical activity, insecurity, emotional reaction, dependency, diet, concerns over medications and side effects). The instrument has only recently been developed and validated in the UK and further research on its utility is being conducted.
The disease-specific instruments reviewed have been developed specifically for patients with angina, MI or heart failure. However, many patients with CHD have several of these diagnoses. It has also been pointed out that patients with CHD usually have other co-morbid conditions which generic instruments may not sufficiently detect important changes [32, 35]. Thus, there is a need for a disease-specific (for CHD) instrument to address this issue.
Cardiovascular Limitations and Symptoms Profile (CLASP)
The CLASP  comprises 37 items that yield four symptoms subscales (angina, shortness of breath, ankle swelling and tiredness) and five functional limitation subscales (mobility, social life and leisure activities, activities within the home, concerns and worries and gender). Each subscale has four to six questions and scores are weighted to provide a total for each subscale (normal or mild to severe). The CLASP has been validated in patients with chronic stable angina and further research is required before it can be recommended for routine use.
One of the difficulties facing researchers and clinicians in the assessment of HRQL is the selection of instruments: generic or disease-specific. A recent review has concluded that, overall, disease-specific instruments of HRQL are more responsive than generic ones . New instruments and novel methods for measuring HRQL in patients with CHD are being developed at a rapid rate. For example, individualized instruments, such as the Patient Generated Index , appear promising even though they are in their early stage of development.
HRQL represents the effect of an illness and its treatment as perceived by the patient and plays an important role as a primary outcome measure. There is a wide selection of instruments available but choice should be based on a careful consideration of psychometric properties, relevance and suitability. It should be emphasized that many instruments currently available are rather cumbersome and time-consuming for routine application in clinical practice. There is a need for simple instruments that are responsive, easily applied and rapidly interpreted.
Professor David R Thompson was involved in collection and review of information and literatures as well as manuscript writing. Some of the studies described in the manuscript was conducted by Professor Thompson.
Professor Cheuk-Man Yu was involved in literature review and final endorsement of the manuscript. Some of the studies described in the manuscript was organized by Professor Yu.
- Wenger NK, Mattson ME, Furberg CD, Elinson J: Assessment of quality of life in clinical trials of cardiovascular therapies. Am J Cardiol 1984, 54: 908–13.PubMedView ArticleGoogle Scholar
- Mayou R, Bryant B: Quality of life in cardiovascular disease. Br Heart J 1993, 6: 460–6.View ArticleGoogle Scholar
- Treasure T: The measurement of health related quality of life. Heart 1999, 81: 331–2.PubMed CentralPubMedView ArticleGoogle Scholar
- Thompson DR, Roebuck A: The measurement of health-related quality of life in patients with coronary heart disease. J Cardiovasc Nurs 2001, 16: 28–33.PubMedView ArticleGoogle Scholar
- Wilson IB, Cleary PD: Linking clinical variables with health-related quality of life. A conceptual model of patient outcomes. JAMA 1995, 273: 59–65. 10.1001/jama.273.1.59PubMedView ArticleGoogle Scholar
- McDowell I, Newell C: Measuring health: a guide to rating scales and questionnaires. New York: Oxford University Press 2nd Edition 1996.Google Scholar
- Guyatt GH, Feeny DH, Patrick D: Measuring health-related quality of life. Ann Intern Med 1993, 118: 622–9.PubMedView ArticleGoogle Scholar
- Bowling A: Measuring health: a review of quality of life measurement scales. Buckingham: Open University Press 1997.Google Scholar
- Thompson DR, Meadows KA, Lewin RJP: Measuring quality of life in patients with coronary heart disease. Eur Heart J 1998, 19: 693–5.PubMedGoogle Scholar
- Jenkinson C, McGee H: Health status measurement: a brief but critical introduction. Oxford: Radcliffe Medical Press 1998.Google Scholar
- Bergner M, Bobbitt RA, Carter WB, Gilson BS: The Sickness Impact Profile: development and final revision of a health status measure. Med Care 1981, 19: 787–805.PubMedView ArticleGoogle Scholar
- Visser MC, Fletcher AE, Parr G, Simpson A, Bulpitt CJ: A comparison of three quality of life instruments in subjects with angina pectoris: the Sickness Impact Profile, the Nottingham Health Profile, and the Quality of Well-Being Scale. J Clin Epidemiol 1994, 47: 57–63.View ArticleGoogle Scholar
- Visser MC, Koudstaal PJ, Erdman RA, Deckers JW, Passchier J, van Gijn J, Grobbee DE: Measuring quality of life in patients with myocardial infarction or stroke: a feasibility study of four questionnaires in The Netherlands. J Epidemiol Comm Health 1995, 46: 513–7.View ArticleGoogle Scholar
- Ware JE, Snow KK, Kosinski MK, Gandek B: SF-36 health survey manual and interpretation guide. Boston, MA: The Health Institute, New England Medical Center 1993.Google Scholar
- Brown N, Melville M, Gray D, Young T, Munro J, Skene AM, Hampton JR: Quality of life four years after acute myocardial infarction: short form 36 scores compared with a normal population. Heart 1999, 81: 352–8.PubMed CentralPubMedView ArticleGoogle Scholar
- Dempster M, Donnelly M: A comparative analysis of the SF-12 and the SF-36 among ischaemic heart disease patients. J Health Psychol 2001, 6: 707–11.PubMedView ArticleGoogle Scholar
- Rubenach S, Shadbolt B, McCallum J, Nakamura T: Assessing health-related quality of life following myocardial infarction: is the SF-12 useful? J Clin Epidemiol 2002, 55: 306–9. 10.1016/S0895-4356(01)00426-7PubMedView ArticleGoogle Scholar
- Chau J, Yu CM, Li LSW, Cheung BMY, Lam KB, Ho YY, Fong YM, Ng WWL, Lam YM, Lee PY, Lau CP: An assessment of the morbidity, mortality, and quality of life of patients attending an outpatient cardiac rehabilitation programme. Circulation 1999,100(Suppl 1):I-142.Google Scholar
- Yu CM, Chau J, Li LSW, Kong SL, McGhee S, Cheung BMY, Lau CP: Two-year benefit of cardiac rehabilitation program on quality of life and cost-effectiveness in patients with coronary artery disease. Eur Heart J 2002,23(Suppl):630.Google Scholar
- Yu CM, Li LSW, Ho HH, Lau CP: Long-term changes in exercise capacity, quality of life, body anthropometry, and lipid profiles after a cardiac rehabilitation program in obese patients with coronary heart disease. Am J Cardiol. 2003, 91: 321–5. 10.1016/S0002-9149(02)03159-4PubMedView ArticleGoogle Scholar
- Spertus JA, Winder JA, Dewhurst TA, Deyo RA, Prodzinski J, McDonell M, Fihn SD: Development and evaluation of the Seattle Angina Questionnaire: a new functional status measure for coronary artery disease. J Am Coll Cardiol 1995, 25: 333–41. 10.1016/0735-1097(94)00397-9PubMedView ArticleGoogle Scholar
- Oldridge N, Guyatt G, Jones N, Crowe J, Singer J, Feeny D, McKelvie R, Runions J, Streiner D, Torrance G: Effects of quality of life with comprehensive rehabilitation after acute myocardial infarction. Am J Cardiol 1991, 67: 1249–56.View ArticleGoogle Scholar
- Lim LL-Y, Valenti LA, Knapp JC, Dobson AJ, Plotnikoff R, Higginbotham N, Heller RF: A self-administered quality-of-life questionnaire after acute myocardial infarction. J Clin Epidemiol 1993, 46: 1249–56.PubMedView ArticleGoogle Scholar
- Hillers TK, Guyatt GH, Oldridge N, Crowe J, Willan A, Griffith L, Feeny D: Quality of life after myocardial infarction. J Clin Epidemiol 1994, 47: 1287–96.PubMedView ArticleGoogle Scholar
- Hays RD, Anderson RT, Revicki D: Assessing reliability and validity of measurement in clinical trials. In: Quality of Life Assessment in Clinical Trials: Methods and Practice (Edited by: Fayers P). New York: Oxford University Press 1998, 169–182.Google Scholar
- Valenti L, Lim L, Heller RF, Knapp J: An improved questionnaire for assessing quality of life after acute myocardial infarction. Qual Life Res 1996, 5: 151–61.PubMedView ArticleGoogle Scholar
- Dixon T, Lim LL, Oldridge NB: The MacNew heart disease health-related quality of life instrument: reference data for users. Qual Life Res 2002, 11: 173–83. 10.1023/A:1015005109731PubMedView ArticleGoogle Scholar
- Rector TS, Kubo SH, Cohn JN: Patients' self-assessment of their congestive heart failure: content, reliability, and validity of a new measure, the Minnesota Living with Heart Failure Questionnaire. Heart Failure 1987, 3: 198–209.Google Scholar
- Dougherty CM, Dewhurst T, Nichol WP, Spertus J: Comparison of three quality of life instruments in stable angina pectoris: Seattle Angina Questionnaire, Short Form Health Survey (SF-36), and Quality of Life Index-Cardiac Version III. J Clin Epidemiol 1998, 51: 569–75. 10.1016/S0895-4356(98)00028-6PubMedView ArticleGoogle Scholar
- Dempster M, Donnelly M: Measuring the health related quality of life of people with ischaemic heart disease. Heart 2000, 83: 641–4. 10.1136/heart.83.6.641PubMed CentralPubMedView ArticleGoogle Scholar
- Smith HJ, Taylor R, Mitchell A: A comparison of four quality of life instruments in cardiac patients: SF-36, QLI, QLMI, and SEIQoL. Heart 2000, 84: 390–4. 10.1136/heart.84.4.390PubMed CentralPubMedView ArticleGoogle Scholar
- Dempster M, Donnelly M, Fitzsimons D: Generic, disease-specific and individualized approaches to measuring health related quality of life among people with heart disease – a comparative analysis. Psychol Health 2002, 17: 447–57.View ArticleGoogle Scholar
- Thompson DR, Jenkinson C, Roebuck A, Lewin RJP, Boyle RM, Chandola T: Development and validation of a short measure of health status for individuals with acute myocardial infarction: the myocardial infarction dimensional assessment scale (MIDAS). Qual Life Res 2002, 11: 535–543. 10.1023/A:1016354516168PubMedView ArticleGoogle Scholar
- Lewin RJP, Thompson DR, Martin CR, Stuckey N, Devlen J, Michaelson S, Maguire P: Validation of the Cardiovascular Limitations and Symptoms Profile (CLASP) in chronic stable angina. J Cardiopulm Rehabi 2002, 22: 184–191. 10.1097/00008483-200205000-00010View ArticleGoogle Scholar
- Spertus JA, Winder JA, Dewhurst TA, Deyo RA, Fihn SD: Monitoring the quality of life in patients with coronary artery disease. Am J Cardiol 1994, 74: 1240–4.PubMedView ArticleGoogle Scholar
- Wiebe S, Guyatt G, Weaver B, Matijevic S, Sidwell C: Comparative responsiveness of generic and specific quality-of-life instruments. J Clin Epidemiol 2003, 56: 52–60. 10.1016/S0895-4356(02)00537-1PubMedView ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.