PART IV - QUALITY OF LIFE ASSESSMENT
TABLE OF CONTENTS
BOOKSHOP
Updated on May 16, 2016
PART IV

Quality of life assessment

Mattie Lenzen, Ron Van Domburg, Susanne S. Pedersen

Summary

Treatment options for patients with coronary artery disease have expanded considerably over recent decades. In addition to pharmacological therapy, mechanical revascularisation with bypass surgery or percutaneous intervention can be offered to relieve symptoms of severe ischaemia and improve quality of life (QoL). QoL has gained increased recognition as an important outcome measure in patients with cardiovascular disease, and may serve to bridge the gap between research and clinical practice. Patient-rated QoL predicts mortality and hospitalisations independent of traditional biomedical risk factors, and as such may help identify patients at high risk for adverse clinical events who may require more aggressive treatment. QoL measures may aid in both optimising clinical decision making and patient care, as well as enhancing patient-physician communication.

Introduction

Treatment options for patients with coronary artery disease (CAD) have expanded considerably over the last three decades. In addition to pharmacological therapy, mechanical revascularisation with coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) can be offered to relieve symptoms of severe ischaemia, improve quality of life (QoL), and enhance survival in subsets of patients [1, 2]. Choosing the most appropriate treatment for the individual patient, however, still remains controversial in many cases [3].

Assessment of QoL has gained increasing recognition as an important patient-reported outcome measure (also known as PROs or PROMs) in patients with cardiovascular disease and is frequently used for evaluating the benefits of treatment and the quality of care [9, 4, 5, 6, 7, 8, 9, 10]. The Clinical Outcomes Utilising Revascularisation and Aggressive Drug Evaluation (COURAGE) trial [11] testifies to the utility of incorporating a QoL measure in research and clinical practice, as this trial found that patients with more frequent anginal complaints, as assessed with the Seattle angina questionnaire, derived the most benefit from PCI in combination with optimal medical therapy. This subset of patients with more severe anginal complaints would most likely not be identified in clinical practice based on the clinician’s judgment alone, as physicians tend to underestimate the disability of patients [12, 13]. Moreover, traditional measures used by physicians, such as the Canadian Cardiovascular Society (CCS) classification to determine the extent of angina pectoris and the New York Heart Association (NYHA) functional class to assess the severity of heart failure suffer from their poor observer reproducibility and their poor sensitivity to express treatment-related changes [14, 15]. In addition, the inclusion of the patient perspective (i.e., asking the patient to rate his/ her QoL and the impact of disease on QoL) provides unique prognostic value above and beyond traditional biomedical risk factors, as shown in several studies on CAD and heart failure [6]. Given that this information cannot be captured from patients’ medical records alone, QoL needs to be assessed in its own right using a validated and standardised measure.

Quality of life: Assessment issues

DEFINING QOL

Most people will have some understanding of what “quality of life” means, but in everyday clinical practice the concept is surrounded by confusion with respect to both definition and quantification. This confusion primarily relates to the existence of multiple terms which are used interchangeably, including QoL, health-related QoL and health status. Overall, however, there is a general consensus that QoL is a subjective phenomenon which should, at least, include assessment of symptom status and its effect on physical functioning and mobility as well as social and emotional wellbeing [16]. This information does not necessarily coincide with that of a clinician and should be regarded as additional to clinical evaluation and diagnostic tests [12]. Most of these aspects are incorporated into QoL questionnaires frequently used in patients with CAD ( Table 1).

MEASURING QOL

Over recent decades numerous questionnaires have become available which measure QoL. These instruments help quantify the impact of a chronic disease, such as CAD, but also the effect of treatment on patients from the patient’s perspective. In turn, this provides unique and valuable information to clinicians enabling them to differentiate between patients who may respond suboptimally to treatment, further indicating that this subset of patients warrant a more aggressive or different treatment approach. Consequently, measuring QoL may prove useful in the clinical decision-making process with regard to which treatment to favour for individual patients [17, 18, 19]. In this context, it is important to emphasise that patients with an identical clinical profile can have a dramatically different response to a given treatment in terms of their QoL [20]. Therefore, it is important that the instrument used measures the health dimensions relevant to the patient population of interest [21].

Irrespective of the choice for a specific questionnaire, the instrument must have demonstrated validity and reliability. If used as an outcome measure, the instrument also needs to be sufficiently sensitive to detect changes following an intervention. In addition, a questionnaire should only be used if it is available in the native language of the patients under evaluation and has been subjected to rigorous psychometric analysis, as the questionnaire may contain culturally sensitive items which are not translatable or relevant to all cultures. In case a questionnaire is not available in a specific language, a complete repetition of the validation process of the original questionnaire (including back-translation and pretesting) is required as cultural differences may affect outcome when only using a simple translation procedure [22]. Finally, the QoL measure should only be completed by patients and not by proxies, such as relatives or health care professionals, as clinicians, in particular, tend to underestimate their patients’ morbidity [23]. Therefore, patient self-reporting is the most valid method for obtaining the patient’s perspective on the influence of disease and/or treatment on QoL.

GENERIC VERSUS DISEASE – SPECIFIC INSTRUMENTS

QoL measures can be divided into generic and disease-specific instruments. Generic instruments are key to comparing outcomes across different populations, such as the QoL of CAD patients as opposed to the QoL of cancer patients. These instruments provide crude estimates that can be combined with survival and costs for cost-effectiveness analyses. By contrast, disease-specific instruments focus on collecting detailed information (on a particular disease or particular intervention) at the level of individual patients (intra-individual measures) and/ or for comparing QoL of groups, such as men versus women, presence of comorbidities versus their absence (inter-individual measures). These questionnaires are responsive both to varying conditions and to change over time [24].

A limitation of generic instruments is that they may not be sufficiently sensitive to detect subtle treatment effects or specific problems related to a particular illness, whereas a disease specific questionnaire may not capture overall life satisfaction and may miss relevant aspects of the impact of disease on QoL [25, 26]. Although the discussion regarding the most favourable questionnaire (generic versus disease-specific) is still ongoing, there seems to be some consensus among QoL researchers that, for the time being, using both instruments provides the most comprehensive information [25].

SNAPSHOT VERSUS SERIAL MEASUREMENTS

Another important issue related to the assessment of QoL is not only the question of when, but also how frequently, QoL should be assessed. Thus, a decision should be made on the optimal (feasible) timing and whether to collect data once (cross-sectional snapshot) or on multiple occasions (longitudinal measurement). The advantage of the latter compared to the former is that serial assessments provide information about changes over time (e.g., pre and post-PCI), whereas a snapshot measurement helps identify QoL deficits between individuals and groups of patients at one point in time only [27]. The optimal timing and choice between either strategy will depend highly on the principal objective of the evaluation and what is feasible logistically.

Selection of QoL instruments

One of the most important challenges facing researchers and clinicians when assessing QoL is which instrument(s) to choose, as there are numerous instruments available. Over recent decades hundreds of validated QoL questionnaires have been developed for chronic diseases. The choice will depend on the group of patients and/or disease under study, the measure’s psychometric properties and length (i.e. the number of items), as well as the availability of the QoL questionnaire in the language required. An additional aspect to consider is whether to include a generic or disease-specific instrument, or both. Moreover, when used in clinical research it may be important to be able to compare the results with earlier findings, thus warranting the use of the same instrument(s).

It should also be noted that many QoL instruments are copyright protected and permission (registration), with or without the payment of a license fee, may be required.

For the evaluation of QoL in patients with CAD and other cardiovascular diseases, however, a much smaller list of validated questionnaires is available. A short list of frequently used instruments (validated in multiple languages) is presented in Table 1. In patients with CAD, the most commonly used generic measure is the Short-Form Health Survey 36 (SF-36) or the shorter version (SF-12), whereas the Seattle Angina Questionnaire (SAQ) and HeartQoL are the most frequently used disease-specific questionnaires [6, 7].

QoL as an outcome tool

A NEW BASELINE CHARACTERISTIC

Several studies have reported on the predictive value of QoL in relation to adverse outcome (e.g., mortality and/or hospitalisation) in patients with CAD and chronic heart failure. In most of these studies, impaired QoL was identified as an independent risk factor for adverse clinical outcome and also shown to add to the level of prediction of mortality and re-infarction above and beyond demographic and clinical baseline characteristics [28]. Moreover, Mommersteeg et al. reported a relation between QoL and cytokine levels in patients with heart failure, suggesting that cytokine activation may be one of the pathways involved in the relationship between QoL and adverse clinical outcome [29]. However, given that the mechanisms explaining the association between QoL and poor prognosis are not yet fully understood, it cannot be excluded that QoL is merely a risk marker rather than a risk factor for poor prognosis [6].

REPRESENTING THE PATIENT PERSPECTIVE

During the last few decades, QoL has gained increased recognition as an important outcome measure in epidemiology and clinical health services research in general and cardiovascular research in particular, with QoL assessment and its determinants recommended as a means to bridge the gap between research and clinical practice [4, 7, 36]. Information on QoL may prove useful in identifying patients at high risk for adverse clinical outcomes who consequently may benefit from more aggressive treatment, including invasive, pharmacological and/ or behavioural intervention or a combination hereof [19, 30].

Furthermore, QoL assessment may help in the clinical decision-making process in patients with cardiovascular diseases as various treatment options exist. Both patients and physicians should weigh the benefits and risks of a given treatment as measured by improvement in survival and QoL (including symptoms). What is more, discrepancies are known to exist between patient and physician preferences with respect to the aim of treatment (i.e., prolonged survival versus improved QoL). In this context, it is also important to emphasise that disease may have a differential impact on individual patients, although patients may respond differently to treatment [31]. These aspects should, if possible, be integrated into the decision-making process. Additionally, the wellbeing paradox should be mentioned as an extreme example of patients with severe health problems who report having a good QoL despite severe illness [32].

Clinical utility of QoL assessment

QoL assessment describes the effect of disease and treatment as perceived by the patient and can, therefore, play an important role as an outcome measure in clinical practice. In addition to using QoL as an outcome measure, quantifying patients’ QoL can be used as a performance measure of routine clinical care (including benchmarking). Moreover, when assessed on a regular basis (e.g., during each outpatient visit), additional information is gathered on how the patient’s health evolves [7]. In addition, patients tend to be seen by more than one physician, and physicians are not likely to remember how a specific patient was doing at a previous visit due to the large turnover of patients. Using an instrument evaluating patients’ self-reported health can therefore provide relevant and important information which might otherwise be overlooked [33].

A QoL assessment is also advantageous, as it provides an essential point of reference – if assessed prior to treatment for identifying changes over time which may be attributable to the treatment under investigation, as patients essentially serve as their own control [34]. In some cases, however, a pre-procedural QoL assessment may not be possible, such as in patients undergoing a primary PCI. Another advantage of including a QoL assessment is the possibility to use historically collected information on QoL for informing other patients about the effect of proposed treatment option(s). By using the QoL results of previously treated patients, one can better inform future patients about the expected outcome on their QoL after the intervention, including symptom relief, daily functioning and whether the expected improvement will be clinically relevant [35]. The effects of including QoL as a routine measure in clinical practice are currently being explored in the United States and this is supported by the American College of Cardiology [6]. Table 2 summarises the advantages of using QoL assessment in clinical practice.

In contrast to the potential benefits of assessing QoL, it is also important to address barriers to incorporating QoL measures in clinical practice [36]. For instance, these include lack of time, analysing and interpretation of the results (no consensus on which cut-off values to use), lack of information technology support, lack of funding for using copyright protected questionnaires, and also physicians who are not convinced that QoL measurements are clinically relevant. Some physicians even express concerns that QoL assessments identify problems which they are not able or willing (due to lack of time) to address [37]. Additionally, the lack of an infrastructure to collect QoL measurements on a routine basis should not be underestimated [6]. It is, however, important to stress that some of these barriers may be related to a physician’s limited experience with using QoL measures in clinical practice, as in general patients themselves seem to be willing to complete such measures [38, 39]. Crucially, contemporary evidence suggests that the incorporation of a QoL assessment in clinical practice does not increase the duration of patient consultations and hence does not impinge on an already hectic physician schedule [33].

FOCUS BOX 1QoL instruments
  • Qol questionnaires reflect the patient’s perspective
  • they are validated measurements that demonstrate high reproducibilty
  • QoL is an independent predictor for mortality and hospitalisation
  • these measurements may provide additional information on treatment effects
  • QoL measurements can contribute to the decision-making process (regarding choice of therapy)
  • QoL questionnaires may facilitate communication between patient and physician

Conclusions

QoL has gained increased recognition as an important outcome measure in patients with cardiovascular disease, and may serve to bridge the gap between research and clinical practice. These measurements tend primarily to be included in clinical research, when differences in mortality between treatment options of interest are expected to be small. However, there is considerable evidence to suggest that the inclusion of such assessments in everyday clinical practice may benefit patients and help to optimise clinical decision making and patient care. QoL has independent prognostic value above and beyond demographic and clinical risk factors, and assessment may also help unravel morbidity issues which are not generally discussed in routine practice. Hence QoL assessment may help cardiologists to identify subsets of patients at risk for adverse clinical events and as such may influence interventional strategy, and the aggressiveness of medical treatment.

Personal perspective - Mattie Lenzen

The fundamental objective of medicine is not only to cure or improve survival, but also to improve and preserve the QoL of the patient being treated. In this context, it is only natural that this evaluation of patients’ morbidity be part of everyday clinical practice. Yet measuring QoL is reserved mostly for participants in clinical research when differences in mortality between competitive treatments are estimated to be small. This is in spite of evidence that such assessment has many merits and may further serve to optimise the clinical care and management of subsets of patients who, either do not benefit optimally from the treatment offered, or who need more aggressive treatment in order to reduce their risk of adverse clinical events and thereby improve wellbeing and QoL. In short assessment of QoL in daily clinical practice could prove beneficial for patients.

Repeated measurements of QoL rather than one snapshot assessment should be advocated, as deterioration may indicate a worsening of disease severity or failure of the treatment being provided. This tool may help cardiologists to pinpoint subgroups of patients who need a more aggressive treatment and/or adjustment in medication. Furthermore, QoL assessment may help identify patients who should be referred to other healthcare professionals (i.e., psychologists), as their psychological profile may place them at risk for poor QoL and cardiovascular health. Such patients may benefit from a multidisciplinary approach to treatment.

Assessing QoL as part of clinical routine in everyday clinical practice is still being explored and it is not expected that this will become part of standard care in the next few years. Even so, initiatives to include patient reported outcomes, such as QoL, in daily practice are currently being supported by most scientific and regulatory bodies.

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