1Center for Health Services and Nursing Research, Katholieke Universiteit, Leuven, Belgium
2Division of Congenital Cardiology, University Hospitals of Leuven, Belgium
3Institute of Nursing Science, University of Basel, Switzerland
Received 27 March 2004; revised 6 October 2004; accepted 21 October 2004; online publish-ahead-of-print 7 December 2004.
* Corresponding author: Center for Health Services and Nursing Research, Katholieke Universiteit Leuven, Kapucijnenvoer 35/4, B-3000 Leuven, Belgium. Tel: +32 16 336984; fax: +32 16 336970. E-mail address: philip.moons{at}med.kuleuven.ac.be
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Abstract |
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Methods and results We examined 579 adults with congenital heart disease. A subsample of 514 of these patients was matched for age, gender, educational level, and employment status with 446 healthy counterparts. Individual quality of life was assessed using the Schedule for the Evaluation of Individual Quality of Life-Direct Weighting (SEIQoL-DW). Twelve domains affecting patients' quality of life were identified. Family, job/education, friends, health, and leisure time were the most prominent quality of life domains. Significantly fewer patients than control subjects considered financial means and material well-being and future to be important determinants of quality of life.
Conclusion Assessment of quality of life in adults with congenital heart disease that focusses on the individual is appropriate for obtaining in-depth information on issues relevant for patients' quality of life. This represents a paradigm shift in the measurement of this concept.
Key Words: Quality of life Heart defects Congenital Adults SEIQoL
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Introduction |
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There are two major approaches to measuring quality of life: the need approach and the want approach.2 The need approach is a mainstay of quality of life studies. According to this approach, quality of life depends on fulfilment of basic needs, such as good health, sufficient mobility, good physical performance, adequate nutrition, and favourable shelter. In this approach, quality of life is measured using standardized and pre-defined questionnaires about components or determinants of quality of life. The relative importance of each of these components is assumed to be equal for all respondents. Three types of measurement are often used in this respect: (i) generic instruments, which comprehensively assess quality of life in a variety of populations; (ii) disease-specific instruments, which are developed for a particular disease or health condition; and (iii) test batteries, which employ both generic and disease-specific instruments.3
The want approach assumes that quality of life can only be affected by factors important to an individual.2 For example, according to the want approach, quality of life depends on lifestyle, previous experiences, ambitions, and dreams.2 Hence, in this approach, quality of life must be measured with instruments that permit respondents to indicate and respectively rate domains that are specifically important for their quality of life (i.e. individual quality of life). During the last decade, a paradigm shift has taken place in the measurement of quality of life, from one based on the need approach to one based on the want approach. Some now argue that the want approach is the most valid way of measuring quality of life, because it explicitly includes domains that are relevant for the respondents.4,5 This is obviously a limitation of the need approach.
Several methods have been developed for assessing quality of life that use the want approach.6,7 One such method is the Schedule for the Evaluation of Individual Quality of Life (SEIQoL).6 It was developed to examine quality of life from an individual's perspective by assessing issues defined by the respondent that they feel are most important for quality of life. In contrast to pre-defined questionnaires, which assess quality of life in a more functional manner, SEIQoL reflects a more holistic view, because it considers the effects of non-disease-related aspects of life.8 The SEIQoL, therefore, provides critical information on a patient's perspective of quality of life issues. This is important for adequate patient management in integrated healthcare programmes.
Adults with congenital heart disease constitute a relatively new and growing patient population. To meet the specific needs of these patients, understanding psychosocial issues, including quality of life, is critical for developing comprehensive healthcare programmes for this group of patients. Therefore, the goal of the present study was to identify specific issues, or domains, that most importantly affect the quality of life in adults with congenital heart disease. This was achieved in part by comparing differences in individual quality of life as defined by our study group with those defined by healthy counterparts.
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Methods |
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To explore differences between individuals with and those without heart defects, a subsample of 514 adult patients with congenital heart disease were matched with 446 healthy control subjects according to age, gender, educational level, and occupational status (m:n matching). Control subjects were volunteers recruited from a range of high schools, colleges, universities, companies, and administration organizations in our geographical region. From the remaining 65 patients, 15 and eight patients were not selected for matching because they were disabled or received special education, respectively. For patients who were retired (n=5), or unemployed/housewife (n=30) no matching control persons could be recruited because we could not find an organization that was willing to participate. For seven patients, no control person complying with the matching criteria was available.
Variables and measurement
On the basis of a thorough conceptual foundation, we defined quality of life as the degree of overall life satisfaction that is positively or negatively influenced by individuals' perception of certain aspects of life important to them, including matters both related and unrelated to health.10 With this definition, quality of life ought to be measured in terms of life satisfaction. The SEIQoL Direct Weighting (SEIQoL-DW)11 was used to evaluate the aspects of life that were important for individual quality of life in our subjects (i.e. determinants of quality of life). Administration of the SEIQoL-DW includes three successive stages, comprising both qualitative and quantitative assessments:
The SEIQoL-DW permits the calculation of a single index of quality of life by summing the products of the rated level and weighting for each of the five domains. This index ranges from 0 to 100, with higher scores corresponding to higher levels of quality of life.
Although the SEIQoL-DW is known to have high face and content validity,4,5,7,11,12 little evidence was available on other psychometric properties.8 Using the new standards of psychometric testing, our data analyses provided additional validity evidence on test content, internal structure, and relations to other variables, as well as on the stability of the instrument.10 Although the SEIQoL-DW cannot be considered as a measure of quality of life itself, it is a valid and reliable instrument to explore determinants for patients' quality of life.10 Responsiveness of the SEIQoL-DW in patients with congenital heart disease might be problematic,10 and should therefore be scrutinized in further research.
Procedure
Patients were recruited following a scheduled outpatient visit to the Adult Congenital Heart Disease Clinic. After consulting with the advanced clinical nurse practitioner and a cardiologist specialized in congenital heart defects, an independent researcher obtained informed consent from qualifying patients and provided instructions on completing the questionnaires. The researcher remained available to offer clarification if needed. Administration of the SEIQoL-DW averaged 7 min (range 315 min). The study protocol was approved by the local ethics committee.
Two approaches to recruit eligible control subjects were used. First, based on the matching criteria, potential control subjects were identified from the organization's personnel database. These persons were subsequently invited to participate. Second, the aim and procedure of the study was explained to the students of specific classes or to employees of the participating company by using the internal communication bulletin. Persons who were willing to participate could apply for the study. Their demographic characteristics were checked with the matching criteria. If a corresponding patient was included in the study, this control subject could participate.
Data analysis
Both qualitative and quantitative analyses were performed. Analyses were similar to content analysis techniques. For the five patient-designated domains, a standard qualitative analytical procedure was used. The domains, as well as the reasons for why they were important, were transcribed verbatim. The individual statements, in their original form, were subsequently sorted and clustered, according to common content. Each cluster was subjectively labelled according to the best description of the meaning of the statements in that cluster. For each labelled cluster, we calculated the percentage of patients mentioning the corresponding domain. To increase objectivity in the interpretation and to monitor the clustering process, peer debriefings were organized with experts in the field of quality of life and qualitative analyses. Three independent meetings with experts were arranged to reach consensus on the labelling of clusters.
Descriptive statistics of demographic and clinical variables were expressed in percentages, medians, and quartiles. Because an m:n matching was employed, conditional logistic regression on 65 strata was used if the response variable was dichotomous. Although conditional linear mixed models have been developed to be used when response variables are continuous,13 our data did not fulfil the normality assumptions inherent to these statistics. Therefore, we calculated a mean score per group for each stratum and compared these scores between the two groups using a Wilcoxon signed-rank test. No appropriate statistics are available for the analysis of nominal level data when samples are related but unbalanced. Therefore, we used the 2 and MannWhitney U tests to compare some demographic and social characteristics.
All tests were two-sided. The Bonferroni correction was applied to adjust for the inflating type I error in multiple testing. For each test, 12 comparisons were made (12 domains). Therefore, the level of significance was set at P0.004 (0.05 divided by 12).
Since determinants of quality of life may evolve when growing older, we assessed the evolution of important quality of life domains per decade of life. For this purpose, we used the CochranArmitage test for trends.
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Results |
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Regarding the relative importance of the respective domains, family proved to be the most significant determinant of quality of life in adults with congenital heart disease, followed by health, friends, and future (20%). Environment, financial means and material well-being, and nourishment were less important.
On the 0100 scale, the overall SEIQoL-DW index score for this sample of patients was 79 (Q1=70; Q3=87), suggesting that adult patients with congenital heart disease have a relatively good quality of life.
Important quality of life domains per decade of life
We found significant differences among the respective decades of life for three domains: health, family and friends (Figure 2). These data show that health and family become more important with increasing age. On the other hand, friends are less frequently reported by older patients as an important quality of life domain. The observed differences in the actual status and relative importance were not statistically significant.
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Relationship to type of heart defect
We examined whether the type of congenital heart defect affected the patient's designation of domains deemed to be important for their quality of life. For this analysis, only heart defects that occurred in >5% of the sample were considered, in order to have subgroups of >30 patients. Among patients with tetralogy of Fallot, ventricular septal defect, coarctation of the aorta, congenital stenosis of the aortic valve, pulmonary valve stenosis, or transposition of the great arteries, no differences were found in the percentage of patients who identified respective domains, the actual status or relative importance. This indicates that the type of heart defect does not impact individual quality of life.
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Discussion |
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We found 12 important domains that contribute to the quality of life of patients with congenital heart disease. The majority of patients identified general issues, such as family, job/education, friends, and health to be important determinants of quality of life. The relative importance was highest for family, then health, friends, and future. This indicates that while job/education was, for many patients, an important determinant of quality of life, it was considered less important when compared with the other nominated domains. Only a few respondents identified concerns about their future as an important indicator of quality of life, although its relative importance was higher compared with that of many other domains.
Quality of life research often focusses on health-related quality of life. Indeed, patients' health is consistently identified as an important determinant of quality of life. However, in the present study, only 59% of the patients with congenital heart disease identified health as an important determinant of quality of life. Moreover, fairly equal numbers of patients and healthy control subjects identified health as important. This confirms that, by focusing on health-related quality of life, investigators substantially overestimate the impact of health-related factors and seriously undervalue the effect of non-medical phenomena.5
Our findings identified only two significant differences in important determinants of quality of life between patients with congenital heart disease and healthy persons without heart defects. Financial means and material well-being was an important determinant in twice as many control subjects as patients. The relative importance of this domain was also higher in controls than in patients. Severe heart conditions or previous operations prompt patients to put material aspects in proper perspective. This could potentially explain why fewer patients consider financial means and material well-being to be important.
The present study also revealed that the type of heart defect does not impact factors deemed important for quality of life in adults with congenital heart disease, neither the actual status nor relative importance of the respective domains. This is in line with the finding that the quality of life in our patient sample was only marginally associated with the severity of the heart defect.33 It can therefore be assumed that patients with severe conditions do not necessarily consider other aspects of life as significant.
Implications
This investigation provides crucial information for healthcare professionals to understand better the consequences of heart defects on patients' quality of life. This study goes beyond the traditional focus of functionality problems by providing a holistic outlook on living with congenital heart disease. This holistic approach is key in comprehensive, interdisciplinary healthcare programmes for these patients.
The employment of the SEIQoL-DW in this study supports the utility of this instrument to practitioners interested in measuring their patients' quality of life for clinical purposes. The time needed for completing the SEIQoL-DW is acceptable (average 7 min), and analysiswhich is complex if used in researchis not necessary because only the individual responses are relevant.
Methodological issues
This article reports the application of a relatively new method of measuring quality of life in a sample of adults with congenital heart disease. The use of a patient-centred, individualized measure, such as the SEIQoL-DW, is more appropriate than standardized instruments,34 because it provides a detailed picture of quality of life issues relevant to patients. Moreover, the SEIQoL-DW counters common problems inherent to most quality of life measures (e.g. focussing primarily on limitations and impediments, without considering positive elements that contribute favourably to quality of life). Indeed, quality of life is increasingly considered to be a positivistic concept.10
Despite these positive aspects, there are specific problems with individualized measures of quality of life. Some patients may have difficulty understanding the system.8,34 In the present study, this problem was observed in 8% or 50 of the 629 patients. These patients were excluded from the analysis without affecting the sample size. Furthermore, the interpretation and analysis of data stemming from individualized measures is complex,34 mainly because the data are qualitative. To address this issue, we used a qualitative analysis procedure that is similar to content analysis techniques. To mitigate subjectivity in the interpretation of data, final labelling was done in consensus meetings with experts in quality of life and qualitative research. Although the data collection and analysis may be complex, we have demonstrated that it is feasible to use the SEIQoL-DW in large samples. Indeed, this is the first large-scale study using an individualized quality of life instrument.
This study favourably used a large sample size. Since we enrolled patients from an outpatient clinic of a tertiary care centre, it may be argued that the sample was not representative of the entire population of adults with congenital heart disease. Many patients who are born with a rather benign cardiac anomaly are treated in the first years of life and do not need continuing check-ups at a university hospital. In addition, the strict inclusion and exclusion criteria implied that the sample was not even, as such, representative of all patients attending the outpatient clinic. We did not include patients under 18 years of age, and patients with mental retardation. The former group was excluded because questionnaires developed for adult populations are not valid to be used in adolescents. The latter group was debarred from inclusion because self-report by questionnaires requires intact intellectual abilities.
Twelve per cent of the eligible patients did not participate in the study. Since the reason not to take part in the study could very well be related to the patient's quality of life, the introduction of a potential selection biasalthough limitedcould not be excluded. A possible under-representation of specific heart defects in our patient sample, however, failed to affect our results since we showed that both quality of life33 and its determinants (present study) are not influenced by the type of heart defect exhibited by the patients studied.
Although this study meets the new emerging standards of quality of life measurement, it does not fully dismiss the utility of generic and disease-specific instruments in measuring specific components of quality of life. While these instruments may not measure all aspects of quality of life, they may be useful in measuring disability related to specific diseases and effectiveness of treatment. Hence, such instruments may identify actionable items with respect to self-perceived health status of functional abilities.
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Conclusion |
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Acknowledgements |
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References |
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