Centre for Health Services and Nursing Research, School of Public Health, Catholic University of Leuven, Leuven, Belgium
Correspondence and offprint requests to: Sabina De Geest PhD, RN,NFESC, Centre for Health Services and Nursing Research, School of Public Health, Catholic University of Leuven, Kapucijnenvoer 35, B-3000 Leuven, Belgium.
Introduction
Quality of life has emerged as an important outcome measure in health care over the past two decades and is increasingly used to evaluate treatment options. Indeed, understanding the quality-of-life implications of a new treatment modality in addition to studying its effects in terms of incidence of complications and mortality rate provides a more sophisticated and balanced view of treatment effects. Quality-of-life data offer a more complete understanding of the benefit/burden ratio associated with medical treatments in view of patients' physical, emotional/mental and social functioning. Furthermore, it provides a significant contribution to the allocation of health care resources, in determining reimbursement policies, and in individual medical decision processes [1,2].
Although quality of life has been extensively studied in transplant patients, a systematic assessment of symptoms and of side-effects related to immunosuppressive drugs is rarely integrated into quality-of-life research. However, the patient's appraisal of side-effects of immunosuppressive drugs is of utmost importance to understand better the quality-of-life issues for transplant patients. This text tries to clarify the definitions used to assess quality of life. We shall then proceed to elaborate on the importance of assessing side-effects of immunosuppressive regimens in transplanted patients within a quality-of-life framework.
Definition of quality of life
Although quality of life is increasingly assessed in research and clinical practice, no consensus exists concerning the definition or the measurement of this multidimensional concept. Quality of life can include a number of dimensions that refer to physical, psychological, mental, emotional, social, spiritual, and vocational function [3,4]. Though some of these dimensions may be relevant to understanding specific human responses to a particular treatment option (e.g. spiritual beliefs), they are not necessarily regarded as pertinent to medical and health services research.
Based on the WHO definition of health, defined as `a state of complete physical, mental and social well-being and not merely absence of disease or infirmity' [5], health-related quality of life is operationalized by assessing the domains of physical, mental/cognitive, and social functioning. It is the health-related quality of life that is traditionally measured in clinical trials and medical research to evaluate the benefit/burden ratio of new treatment modalities.
Testa and Simonson's [6] conceptual scheme of the domains and variables involved in quality of life provides a useful framework in unravelling the different components of health-related quality of life. This model operationalizes health-related quality of life based on the physical, psychological and social domains of health. Each of these domains comprises an objective as well as a subjective dimension. The objective dimension reflects the health status of a patient based on an objective evaluation of his/her functioning. The subjective dimension reflects the patients' perceptions of their physical, psychological and social functioning. Both dimensions are relevant in that they contribute to a better understanding of the patients' overall health-related quality of life [6].
Each of the three health domains can be further operationalized. The physical domain encompasses for instance ambulation, mobility, fatigue, pain, sleep, and ability to perform daily activities. Depression, anxiety, emotional well-being, and cognitive status fall within the mental/cognitive domain. The social domain of health-related quality of life includes, for example, work status, role functioning, personal relationships, and sexual functioning [6]. Again, each variable can be assessed from a subjective and an objective perspective.
Patients' appraisal of side-effects in quality-of-life assessments in transplant recipients
Traditionally, side-effects of immunosuppressive regimens have been evaluated based upon their impact on morbidity and mortality. Indeed, the occurrence of nephrotoxicity, hypertension, malignancies, osteoporosis, and diabetes are closely monitored during the post-transplant course as they may negatively affect the transplant recipient's clinical outcome. Going back to Testa and Simonson's quality-of-life model [6], health-care workers have traditionally relied upon objective criteria as the primary means of evaluating treatment side-effects. While the objective component of quality of life has been well documented and integrated within clinical transplant practice, the subjective component is less well understood.
The transplanted patient's subjective appraisal of side-effects and of the perceived associated distress is a key to understanding the balance between benefit and burden of immunosuppressive regimens after transplantation. Some side-effects (e.g. impotence, muscular weakness, gingival hyperplasia) have little or no direct effect on morbidity and mortality, yet can be perceived by transplanted patients as extremely disturbing. Assessing the transplant recipient's subjective experience of symptoms associated with his/her immunosuppressive regimen falls within the subjective domain of quality of life assessment.
Conceptualization of transplant patients' symptom experience
Symptom experience consists of two different, although linked concepts, i.e. symptom occurrence and symptom distress [7]. Symptom occurrence, the cognitive component of symptom experience, can be measured along the dimensions of frequency, severity, and duration of symptoms. Symptom distress refers to the mental anguish or suffering caused by the symptom and is the emotional component of symptom experience [7]. Previous research in transplant recipients showed that the most frequent side-effects of immunosuppressive drugs are not necessarily the most distressing ones, and vice versa [8,9].
Relevance of symptom experience for transplant research and clinical management
For several reasons the transplanted patient's symptom experience, i.e. symptom occurrence and symptom distress, are parameters that are relevant both for transplant research and for clinical management. First, higher levels of symptom distress are associated with lower perceived overall quality of life [6,1012]. Second, symptom distress may trigger non-compliance with the immunosuppressive regimen [13]. For instance a young female transplant recipient may stop taking immunosuppressive medication, because the cosmetic side-effects are extremely disturbing (changed facial and body appearance, i.e. moon face, buffalo hump and increased hair growth). Third, information concerning the transplanted patient's symptom experience can be used for pre- and post-transplant education to complement information about the `traditional' side-effects of immunosuppressive drugs.
Measurement of symptom experience
The first instrument assessing the patient's symptom experience associated with immunosuppressive regimen was the Transplant Symptom Frequency and Distress Scale [10,11]. This 27-item instrument was developed in the early 1980s and measured the symptom frequency (only one dimension of symptom occurrence) and symptom distress associated with side-effects of triple therapy (i.e. cyclosporin, azathioprine, and corticosteroids). Our research group performed consecutive adaptations of Lough's instrument [10,11], resulting in the `Modified Transplant Symptom Occurrence and Symptom Distress Scale' that measures the transplanted patient's symptom experience. Adaptations were based on a comprehensive literature review of side-effects of immunosuppressive drugs, on our previous research on symptom experience associated with these side-effects [8,9], as well as by expert review. The last version of the instrument includes 45 symptoms related to side-effects of tacrolimus, cyclosporin, corticosteroids, azathioprine, and MMF. The items are scored on a 5-point rating scale ranging from 0 (never occurring) to 4 (always occurring) for symptom occurrence and from 0 (not distressing at all) to 4 (terribly distressing) for symptom distress respectively (Table 1). A recent study in 113 renal transplant recipients (70 male/43 female), using this approach to assess symptom experience with triple therapy of cyclosporin, corticosteroids, and azathioprine, resulted in a rank order of the five most frequent and distressing symptoms for male and female renal transplant recipients respectively (Table 2
). Bruises and brittle skin were the most frequent symptoms in both groups. Bruises, increased hair growth, muscular weakness, and brittle skin occurred in both genders. The most distressing symptom in male and female transplant patients was impotence and muscular weakness respectively. The list of the five most distressing symptoms showed less concordance among genders compared to the list of symptom occurrence. Only muscular weakness was perceived as highly distressing by both genders. These results show the feasibility evaluating the transplanted patient's subjective symptom experience as an important aspect of quality-of-life assessment in transplantation.
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Quality of life is becoming increasingly important to evaluate treatment outcomes. Evaluation of side-effects of immunosuppressive drugs has to be regarded as an essential component of quality-of-life assessment in clinical trials and outcome studies in transplant populations. Side-effects should be evaluated from both an objective and subjective perspective. The subjective dimension refers to the patient's assessment of side-effects. It can be assessed by evaluating symptom occurrence and symptom distress. Reliable and valid measurements are possible using an instrument such as the Modified Transplant Symptom Occurrence and Symptom Distress Scale. Data on symptom occurrence and symptom distress provide crucial information for life-long management of the patient after transplantation.
Acknowledgments
Based on Moons P, Fairchild S, De Geest S. Patients' appraisal of side effects in quality of life assessments of immunosuppressive regimens. In: Cochat P, Traeger J, Merieux C, Derchavane M, eds. Immunosuppression Under Trial. Kluwer Academic Publishers, Dordrecht, 1999, 6980. (With kind permission from Kluwer Academic Publishers).
References