0277-9536191 $3.00+ 0.00 Copyright Q 1991Pergamon Press plc

Sm. Sci. Med. Vol. 32, No. 9, pp. 981-987, 1991

Printed in Great Britain. All rights reserved

UNDERREPORTING

BY CANCER PATIENTS: OF RESPONSE-SHIFT

THE CASE

I. S. BWTVELT’ and F. S. A. M. VAN DAM’,* l ‘Psychological Laboratory, Department of Clinical Psychology, University of Amsterdam, Weesperplein 8, Amsterdam, The Netherlands and *The Netherlands Cancer Institute, Department of Psychosocial Research and Epidemiology, Antoni van Leeuwenhoekhuis, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands Abstract-There

are a lot of studies in which self-report questionnaires are used, showing that cancer patients do not have a lower quality of life than the normal healthy population. This seems to be in contrast with the results of studies in which more extensive interviews have been used and to the everyday experience of physicians, nurses and other caretakers. This phenomenon of underreporting seems to hold true also for other patient groups. Judgment theories explain how the perception of quality of life arises. These theories indicate how the conceptualization of the dimension to be measured, changes under the influence of a (highly significant) life event, such as getting a life threatening disease. These theories hold that there will be a concurrent change in the internalized standard on which the patients base their perception. Thus a real effect, for example a decrease in quality of life as a result of cancer, can be obscured totally. Until an empirically proven solution to this problem has been found, we recommend that answers in questionnaires concerned with quality of life, psychological distress and the like should be approached with due caution. Key words-underreporting,

response-shift,

quality of life, cancer patients

INTRODUCTlON

Evaluation of clinical modalities for the treatment of cancer has typically focused on outcome indicators such as length of survival, retardation of the disease process and control of major physical symptoms. Clinical decision-making often is guided by similar endpoints, with relatively little systematic attention being paid to how various treatments affect the patient’s quality of life. In recent years, however, increased interest has been shown in the determination of the extent to which medical treatments affect the quality of life. It would be desirable to measure the quality of life as a function of circumstances and treatment, but what does the concept refer to? Quality of life is a global or multidimensional concept [l] with aspects of emotional and of rational judgment. The multidimensionality of this rather vague concept is clear from the fact that an analysis requires statements on sideeffects of treatment (e.g. fatigue and malaise, nausea, appetite loss, etc.), limitations in functional status, disruption of social roles and relationships, psychological distress or psychiatric morbidity. Quality of life can be judged by an external observer or the subject herself. Because of the stressful nature of the disease and its treatment, emotional distress has always been considered an important aspect of quality of life in cancer patients [2-4]. A favorite method of assessing emotional distress is by self-report questionnaires or interviews. It is on this aspect of quality of life measurements that we will concentrate in this paper.

*To whom correspondence

should be addressed. 981

Compared to other patient groups or to nonpatients, cancer patients show a higher level of physical complaints. More remarkable, however, is the fact that they show no difference from the comparison groups in terms of psychological complaints: a phenomenon to which the term ‘underreporting’ seems applicable. This paper presents an attempt to analyze the causes of this so-called underreporting of psychological complaints. We will first discuss results of some studies of the quality of life in cancer patients, then of the quality of life in other patients, handicapped persons and victims. In the last section we will discuss the possible origin of the hitherto unexplained phenomenon of underreporting. RESULTS OF

QUALITY OF LIFE STUDIES IN CANCER PATIENTS

The results of research into the effect of cancer and cancer treatment on quality of life are not very consistent. De Haes [S, p. 8101 concludes on the basis of a literature survey that of all the dimensions of quality of life only somatic complaints and the patient’s level of activity differ between various groups of cancer patients. Differences in overall quality of life are rarely found. One illustrative example is the following. In a study among breast cancer patients who had been treated with cytostatic drugs, we examined their pattern of complaints and general well-being by means of a self-report questionnaire [6]. This instrument was devised to measure the quality of life of cancer patients. The reliability (Cronbach’s alpha) of this questionnaire was above 0.80; the validity was determined as content, discriminant and predictive validity. Three.groups of patients

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were compared: women with advanced disease who were treated with cytostatic drugs, women who were undergoing adjuvant chemotherapy, and a control group of women whose treatment by amputation and/or radiotherapy appeared to have been curative. The groups treated with cytostatic drugs were found to have a significantly higher complaints score than the control group, and the average complaints score of the treated groups was also higher during the period they received the cytostatic drugs than during the rest period. On further consideration of the items on the complaints list, it appeared that the extent to which a number of physical complaints occurred differed from group to group in the expected direction. The complaints concerned are fatigue, loss of energy, nausea, lack of appetite, shivering, shortness of breath, stomach-ache, constipation and vomiting. However, the extent to which psychological complaints-nervousness, worry, depression, insomniaoccurred hardly differed between the chemotherapeutic groups and the control group. Moreover, for the cluster of psychological complaints, it also holds true that their intensity in the groups treated with cytostatic drugs did not vary between the injection and rest periods which was, on the other hand, the case with the most common physical complaints, i.e. nausea and lack of appetite. Finally, we found a discrepancy between the high physical complaint level and the not inconsiderable degree of well-being reported by the patients. When scanning the literature we discovered that our findings were by no means unique. Also if cancer patients are compared to other (non-cancer) patients, there are no differences in most of the indicators of life quality, such as overall quality of life, mental functioning, fear, depression, wellbeing, daily activities and resumption of one’s work. Some examples of this type of research are the following. Cassileth [7] compared the emotional reactions of melanoma patients with those of patients suffering from other dermatological disorders. In this study The Mental Health Index of the General Well-Being Scale, a self report questionnaire which measures anxiety, depression, general positive affect, emotionalities and loss of behavioral or emotional control was used. This measure is validated for the general population and for psychiatric patients. The scores of a representative sample of the American population were used as baseline reference data. The results demonstrated a significant difference in mean score between the melanoma patients and patients with other dermatological disorders, “with melanoma patients indicating superior psychologic well-being”. Moreover, “the mean score for patients with melanoma (was) slightly and insignificantly better than for the general public”. As a possible explanation for these findings, the researchers postulated “profoundly diminished self-esteem among nonmelanoma dermatology patients and intensified utilization of psychic resources among melanoma patients”. In another study, Cassileth [S], using the same measures, compared the psychological status in five groups of physically ill patients (with arthritis, diabetes, cancer, renal disease or dermatological dis-

orders) and in depressive patients. Subscale and total mental health scores for the five groups of physically ill patients all differed significantly from those of the patients under treatment for depression. With the exception of the depressed patients, no group of patients differed significantly from the general public on all these psychological variables. Furthermore, patients with newly diagnosed illness had poorer mental health scores (greater anxiety, depression and loss of control) than patients who had been living with their illness for longer periods. Better mental health scores were found with each older group of patients being studied. The authors explain these results by claiming that patients (with the exception of those with terminal disease) manage to adapt and adjust to their chronic illness. However, there is a lack of information on the means by which physically ill patients remain psychologically intact. Craig and Abeloff [9] studied psychiatric symptomatology in cancer patients. A self-report symptom inventory was given to 30 patients of an oncology unit. The results showed “the mean scores for the total group of patients on all symptom dimensions are relatively low and virtually identical to those which have been reported for normal populations. (. . .) 70% or more of the patients received scores under 1.O (item score range O-4) on 7 of the 9 factors, indicating minimal levels of distress in these symptom complexes”. The results on the factors depression and somatization formed an exception: more than 50% of the patients reported a moderate to high level of depression and 43% reported a higher level of somatization. However, the authors noted that the latter should perhaps be seen as a direct result of the physical symptoms of the disease and not as an indication of psychological distress. In a study on depression among cancer patients, Plumb and Holland [IO] found a similar difference between the scores on physical and non-physical items in the Beck Depression Inventory. This instrument has been validated for other categories of patients. The fact that the depression score of cancer patients was, on average, higher, although not significantly so, than the depression score of the healthy members of their families, is caused by the physical items. On the non-physical items-sadness, sense of failure, guilt, dissatisfaction, self-dislike-the cancer patients did not differ from the healthy members of their families. This phenomenon is not only observed in cancer patients. There are several studies, in which self-report questionnaires are used, showing that cancer patients are not more anxious, more depressed or unhappier than other patient groups or even than the normal, healthy population. This seems to be in contrast to the everyday experience of physicians, nurses and other caretakers, and to the results of studies in which more extensive interviews have been used [ll-131. RESULTS

OF STUDIES ON QUALITY OF LIFE IN OTHER PATIENT GROUPS

Cameron et al. [ 141reported on a study of satisfaction, frustration, and mood in groups of physically handicapped and of blind persons respectively. A

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Underreporting by cancer patients self-report questionnaire was used which included questions on satisfaction with life, difficulties encountered, mood, contemplation of suicide, and frustration. The results which emerged with regard to ‘life happiness’ showed that experienced frustration and future perspective were related to ‘income level’, and not to ‘being handicapped or not’. There was also no difference in mood between handicapped and ablebodied. ‘Difficulties experienced in life’ proved to be related to both ‘income level’ and being handicapped or not’. One striking finding is that the handicapped group reported having contemplated suicide considerably less often than the matched able-bodied group; the number of suicide attempts did not differ between the handicapped and able-bodied groups. In summarizing their findings, the researchers state that the study uncovered no evidence of a difference between the handicapped and normals in selfreported life satisfaction. And they added: “that handicapped persons more frequently judged and reported their lives as more difficult lends credibility to their reports of satisfaction”. Another, rather morbid study which demonstrates a discrepancy between clinical experience and selfreport questionnaire scores, is a comparative study of the happiness level of paralysed victims of traffic accidents and winners of lotteries by Brickman et al. [15]. By means of a telephone interview, questions were asked regarding, among other things, present happiness level, happiness level in the past, pleasure in everyday occupations, and whether they attributed their fate to themselves, to others, to the outside world, or to chance. Although the lottery winners saw their fate as highly positive, and the accident victims saw their fate as highly negative, the researchers observe: “neither outcome was rated as extremely as might have been expected”. Although the accident victims scored significantly higher on ‘past happiness’ than the control group, and significantly lower on ‘present happiness’, the authors emphasize that: “the paraplegic rating of present happiness is still above the midpoint of the scale and the accident victims did not appear nearly as unhappy as might have been expected”. Brickman et al. related these findings to already existing literature which shows happiness to be relative; people from poorer areas are not less happy than people from more prosperous districts, and blind or handicapped people are not unhappier than the healthy population. The same holds with regard to satisfaction, a variable which has frequently been used by organization-psychologists, and which is often used as one of the indicators for quality of life. Gutek [la] found a comparable discrepancy between the high level which is generally reported, and the much lower expectation researchers have of the satisfaction level. This concerns satisfaction in many areas: job, life, governmental agencies, etc. The reason to distrust the level of reported satisfaction more than the expectations of the researchers is that these self-report scores do not correspond to a great extent with behavioral measures for satisfaction. Moreover, even in situations where dissatisfaction is notoriously high, such as in production line work, the reported dissatisfaction is not high. “People at low as compared to high socioeconomic levels are not more dissatisfied with WM32/S--8

their natural environment, the informational media and political leaders” (Andnews and Whitey, 1964, quoted by Gutek [16, p. 491). Another point which may be dubious concerns the reported satisfaction level. In general, people tend to rate their own experiences more favorably than those of others. With regard to quality of life measures, people regularly rate their own lives as more satisfactory than other people’s lives. EXPLANATIONS

FOR UNDERREPORTING

Summarizing the problem, we can state that the findings with regard to the quality of life in cancer patients are inconsistent and that there often is a discrepancy between the degree of negative feelings as they are reported by the patients, and those we suspect they are actually experiencing (171. This does not apply to cancer patients only, but also to other patient groups. This phenomenon of ‘underreporting’ occurs most frequently in self-report measures. Underreporting seems to play a role especially with regard to emotional behavior or attitudes and not so much with regard to somatic symptoms like neusea and vomiting or fatigue. We thus assume that patients report less emotional distress, satisfaction or the like than is actually present. To explain this phenomenon one must turn to theories which indicate how people adjust to extreme negative experiences. There are three kinds of theories in this respect: the psychoanalytic theory of ‘defense mechanisms’, the ‘crisis-theory’ and the ‘judgment theory’. Cancer patients mobilize defense mechanisms, especially denial: the patient hardly allows the threatening reality to become conscious [18, 191. The denial might concern symptoms of the illness, the diagnosis, the affective meaning, but also the consequences, such as progressiveness or death. Bahnson and Bahnson 1201compared cancer patients to normal subjects. On the basis of data from interviews and various tests they conclude that cancer patients tend to deny and repress conIIictua1 impulses and emotions to a higher degree than do normal people. Hughes indicates on the inverse relationship between denial and depression. A study of breast cancer patients demonstrated that patients who used denial had significantly lower scores on depression and anxiety than patients who accepted the diagnosis of cancer more realistically [21]. The crisis theory explains why there is a decrease in quality of life in some cancer patients during the acute phase of their illness while there is none in others. De Haes [l, p. 841 has shown that the quality of life in cancer patients who are in a crisis situation (e.g. shortly after their first operation or while undergoing cytostatic drug treatment) is especially affectively worse than that of patients who are not in a crisis situation (e.g. cancer patients who have been free of symptoms for three or more years). Moreover, the latter group proved not to differ in feelings of well-being from control groups of healthy persons. According to the crisis theory an extremely negative situation disturbs the normal balance between problem perception and the problem solving capacity. In a later phase additional power is usually mobilized

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and the problem solving capacity increases or becomes more effective. Thus, a new balance may be found. The problem solving capacity proved to differ between both groups of cancer patients on the one hand and healthy persons on the other. In addition the relation between the capacity to solve problems and quality of life was stronger in cancer patients who were not in crisis than both in cancer patients who were in a crisis situation and healthy persons. Thus the problem solving capacity in non-crisis patients proves to be more effective in positively influencing the quality of life. In her study De Haes does not go into details of the judgment theories. Nevertheless, also these theoriesthe ‘adaptation level theory’ and the ‘social comparison theory’-are relevant with respect to the selfreporting of well-being by cancer patients. According to the judgment theories one compares the factual situation with some standard. In Helson’s adaptation level theory [22] the starting point is the comparison with earlier experiences. This theory explains changes in judgment of situations and of well-being after extreme experiences. The adaptation level theory assumes that every stimulus is judged in relation to the adaptation level, which corresponds to the midpoint of the rating scale. Which value is assigned to a stimulus depends on the distance or the ratio between stimulus and adaptation level. By adding new stimuli, the adaptation level is shifted in the direction of these new stimuli. According to De Haes [5, p. 8141 as cancer patients may have experienced more extreme negative stimuli their adaptation level may refer to a more negative objective situation. The consequence is that similar circumstances may lead to a more positive judgment of cancer patients than of normals. Starting point of Festinger’s social comparison theory is that people are apt to take the social environment as a reference in the absence of objective criteria for judging their own capacities, opinions and emotions [23,24]. In addition to self-evaluation this tendency to compare with others has more functions. For example, it can contribute to self-enhancement and to the reduction of fear and uncertainty [25]. Since fear, uncertainty and a feeling of being threatened usually accompany cancer(treatment) it is plausible that the social comparison theory applies to cancer patients [26]. An important question is with which reference groups cancer patients are apt to compare themselves. A study of patients with cancer of the breast [27] suggests that these patients tend to make downward comparisons: all interviewed women judged their coping to be as good as or better than that of other women in the same situation. Women with lumpectomies compare themselves to women with mastectomies. Not only the choice of the object of comparison, but also the dimensions along which they compare are chosen in such a way that a favorable self-image results. The tendency of downward comparisons generally occurs in severely threatening situations, that is during a strongly negative affect which causes a decrease in subjective well-being and where no instrumental action can be taken [28]. Contracting cancer is such a situation. Also Taylor [29] was able to prove the downward comparisons,

but she also showed the tendency of patients to choose extreme cases for comparison: patients try to obtain information by exploration of the extremes. From a study by Van den Borne and Pruyn [25, p. 941 of Hodgkin and breast cancer patients it proves that fear and uncertainty correlate significantly with the need for social comparison to fellow patients. According to the study of Molleman et al. [26, p. 91 the need for social comparison to fellow patients is the stronger the less available experts are to give information. The preference is for interaction with fellow patients in comparable circumstances: the less comparable they are, the less informative they are judged to be. As can be expected on the basis of the self-enhancement motive, non-comparable patients, especially those in a worse condition, are regarded as less informative. There proved to be a curvilinear relation between fear and the need for social comparison: this need is maximal at a medium level of fear. At a high level of fear the need declines again. Also in this case there is a preference for fellow patients who are either in a much better or a much worse condition. It can be concluded that cancer patients have a need, induced by the fear and uncertainty accompanying their illness, to compare themselves to fellow patients in similar circumstances. If patients are asked to compare themselves to fellow patients along a given dimension such as coping, they choose those who are worse off, a downward comparison resulting in a favorable self-image. The latter finding makes it probable that cancer patients when asked to judge their level of complaints or their well-being tend to compare themselves to fellow patients and, by force of the self-enhancement motive, to choose a comparative reference group of patients who are worse off. A shift of the choice of reference group induced by the own illness implies a shift in the internal norm. While the actual well-being or level of complaints changes, its evaluation might not change, because the patient compares herself with another reference group. RESPONSESHIFr BIAS According to the above judgment theories there is thus a shift of the internal norm induced by an extreme experience, like for example cancer(treatment). A consequence of this norm shift is that the initial (pretest) and final (posttest) measurement or the experimental vs control group are not measured on the same scale. Cook and Campbell [30, p. 521 call this phenomenon the ‘instrumentation effect’. It is a specific threat to the internal validity of an experimental study. Cronbach and Furby [31] also indicate that a pretest score must be equivalent to a posttest score; that a common metric must exist between two sets of scores. If the standard of measurement changes between the pretest and the posttest, the two ratings will reflect this difference in addition to changes attributable to the experimental manipuConsequently, comparisons of pretestlation. posttest ratings would be confounded by distortion of the internalized scale, yielding an invalid interpretation of the effectiveness of the intervention. When a shift in the internal norm is the basis for underreporting of psychological complaints by

Underreporting by cancer patients

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cancer patients, then underreporting is such an instrumentation effect. Hoogstraten [32] states that one of the effects of most experimental manipulations is that the conceptualization of the subject, with regard to the variable to be measured, changes. The internal standard which the subject uses as a base in pretest and posttest also changes. Because the change in conceptualization of the variable to be measured, and in the internalized standard as basis for assigning the self-report scorethe response shift-by definition only occurs in subjects who are undergoing an experimental manipulation, the danger of such an instrumentation effect cannot be eliminated by the use of a control group. So the score on a given scale may have a different meaning for cancer patients than for the control group of normals. According to Terborg et al. [33] such an instrumentation effect can manifest itself in two different forms of change in response to the experimental manipulation. The simpler type of change, the ‘beta-change’, involves a variation in the level of some existential state, complicated by the fact that some intervals of the measurement continuum associated with a constant conceptual domain have been recalibrated [34, p. 1351. At the posttest of the experimental group there are different scale units than at the pretest of the experimental group or at the posttest of the control group. For example, when a breast cancer patient with metastases has become thoroughly acquainted with ‘anxiety’ as a result of the disease, she rates her initial pre-treatment anxiety level as low, and the degree to which she is troubled by the complaint now as moderate. However, persons from a control group, who have no experience of such a disease, may (for whatever reason) also rate their anxiety level as moderate. This is only a hypothetical example to show how a complaint increasing effect, which results from the treatment, i.e. the cancer(therapy), can remain undetected as a result of the occurrence of a response shift bias, and the insertion of a control group does not help much. A second type of bias change due to experimental manipulation is the ‘gamma-change’. Golembiewsky [34, p. 1351 defines it as: “a redefinition or reconceptualization of some domain, a major change in the perspective or frame of reference within which phenomena are perceived and classified, in what is taken to be relevant in some slice of reality”. Thus it refers to a redefinition or reconceptualixation by the patient of the phenomenon that is measured. For example, the stress which a patient has experienced before her disease might be of a qualitative different order compared to the stress she experiences as a result of a recurrence of her cancer. Fear of death might now play a prominent role in her feelings of stress which obviously was not the case before she got ill. As self-reporting by means of questionnaires is often used in the measurement of the effect of cancer and cancer treatment on the psychological well-being of the patient, the response shift bias is a possible cause of invalidity of the study. The example shows how the increase of the complaint level that the cancer(therapy) actually has can easily be obscured by the response shift bias.

The response shift phenomenon appeared to occur in the measurement of a broad range of variables. MEASURING RESPONSE SHIFI’t A METHOD TO CONTROL FOR THE BIAS

In order to measure the response shift, e.g. the type beta-change, Howard et al. [35] used ‘then’ ratings on which the subjects indicated, in retrospect after the treatment, how they rated their functioning at the time of the pretest. As the ‘then’ pretest scores were assigned at the same time as the posttest, i.e. after treatment, it is probable that these scores were assigned from the same perspective and, in consequence, on the same calibrated scale, and are thus free from response shift bias. The study done by Howard has shown that the effect of an experimental treatment could be better demonstrated by analysis of ‘then’ data, than by analysis of pre- and posttest data. Moreover, the ‘then’-posttest procedure corresponds better to more objective/behavioral indices for change than the pretest-posttest procedure. The difference observed between self-report pre- and posttest scores reflects the unknown amount of real change, and an unknown amount of change as a result of instrumentation, i.e. response shift bias. At the individual level beta-change would be reflected by a difference between an individual’s mean scores across all items on the pretest measure and on the ‘then’-pretest measure. At group level the difference between the mean pretest score and the ‘then’ score in the experimental group is not the same as the difference in the control group [33, p. 1161. Brickman’s findings [15, p. 9211 that accident victims experienced less pleasure. in everyday events in the present, and more pleasure in everyday events in the past, could be seen as a pointer in the direction of this type of response shift. The ‘general present happiness’ score forms the posttest rating, while the ‘general past happiness’ score can be construed as the ‘then’ rating. To the accident victims, the difference between past and present happiness is far greater (past = 4.41 and present = 2.96 on a scale with a range of 0 up to and including S), and contrary to the past-present difference scored by the lottery winners (past = 3.77 and present = 4.00) and the control group (past = 3.32 and present = 3.82). In retrospect, the accident victims rated themselves as being significantly happier in the past than the control group did. This difference could indicate a response shift in the victim group. There is also a significant difference between the ‘present happiness’ of the victims and of the control group: the victims indicate a lower happiness level; thus, in spite of the possible response shift, an effect of the treatment, i.e. the paralysis, can still be demonstrated. A design that is used frequently in social oncology research is the ‘post&&only design with nonquivalent groups’ (30, p. 981. This design should be sup plemented with a ‘then’-test. If underreporting of psychological complaints is a consequence of a shift in the internal judgment norm, it is to be expected that the complaint level of the then-test will be much lower than of the posttest. It might possibly also be lower than the complaint level reported by normal subjects of the then-test. The difference posttest

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(cancer pat.nts) minus then-test (cancer patients) indicates the real increase of complaints under the influence of the cancer(treatment). The difference then-test (cancer patients) minus then-test (normals) is an indication of the response-shift bias. A stronger design, which is more difficult to realize, is the ‘untreated control group design with pretest and posttest’, supplemented with a then-test. In this design the difference between pretest and thentest might prove the presence of a response shift bias. Golembiewsky proposes examination of gammachange, the other type of response-shift bias, through comparison of factor structures over assessments at different moments in time. According to Terborg [33, p. 1161, gamma-change can be identified at the individual level through examination of score-profile shapes (correlations) and dispersions (standard deviations). Perhaps the strongest evidence of this type of change would be substantial differences in both shapes and dispersions. If gamma-change has occurred, the correlation between posttest and then-test itemscores should be substantially greater than the correlations between pretest and posttest measure and pretest and then-test measure. Another form of evidence for gamma change is when the standard deviations of the posttest and then-test profiles are not different from each other but if each is different from the standard deviation of the pretest profile. At the group level a gamma change can be identified as follows. For people in the intervention group the correlation between pretest and posttest profiles should be similar to the correlation between pretest and then-test profiles. But the correlation between posttest and then-test profiles should be greater than the other two correlations. For people in the control group, all three correlations should be. similar in magnitude. People in the intervention group should have larger differences between posttest and pretest vs then-test and pretest standard deviations while people in the control group should have smaller differences on these profiles. The results of a study by Huisman [36] on the preferences of cancer patients in the appreciation of states of health indicate the gamma-change. In this study the subjects repeatedly had to make a choice between two states of health, which were both characterized by a physical as well as a psychological component. The values of both components were often chosen in such a way, that the state of health had a contrarious character. The study showed that the cancer patients weighed the psychological component relatively more and the physical component relatively less heavy than the control-group did. Whenever the level of the mental component was low (for example ‘depression’) the level of the physical component virtually had no effect for the cancer patients. Within the group of subjects who based their choice systematically upon the mental component, the physical component had less influence for the cancer patients than for subjects from the control-group. These findings might point to a process of redefinition or of changed conceptualization of the concept ‘health-state’ as a consequence of the cancer experience.

A different preference study pointing to a response shift of the gamma type was reported by O’Connor [371, who asked the cancer patients and health professionals to choose between two hypothetical treatments: a toxic medicine with strong side-effects vs a less effective medicine without side-effects. Even for a small difference in effectivity the cancer patients preferred the toxic medicine. Healthy subjects first preferred the toxic medicine if the difference in effectivity was substantially larger. The preference difference between the groups not only held when the probability of survival was 90% for the toxic substance, but also when it was only 10%. The author does not ascribe the preference difference only to the fact that the healthy volunteers are faced with a merely hypothetical situation and might therefore be willing to take greater risk on dying. As a possible alternative it was suggested “that patients’ values or utilities have shifted in the process of adapting to their illness. They have changed their reference points upon which to base their judgments”. CONCLUSION

There appear to be sufficient grounds for the assumption that the relatively high quality of life scores of cancer patients in self-reports must be ascribed, at least partly, to a shift of the internal norm relative to the comparison groups. Only a suitable research design, which includes the retrospective pretest, can indicate to what extent this is the case. Until an empirically proven solution to this problem has been found, we recommend that answers in questionnaires concerned with quality of life, psychological distress and the like should be approached with due caution. REFERENCES

1. Haes J. C. J. M. de De Kwalireir Van Leuen Van Kankerparienten. Swets & Z&linger, Amsterdam, Lisse, 1988. 2. Peck A. and Bolland J. Emotional reactions to radiation treatment. Cancer 40, 180-184, 1977. 3. Nerenz D. R., Leventhal H. and Love R. R. Factors contributing to emotional distress during cancer chemotherapy. Cancer SO, 1020-1027, 1982. 4. Worden J. W. and Weisman A. D. The fallacy in mastectomy depression. Am. J. Med. Sci. 273, 169-175, 1977. 5. Haes J. C. J. M. de and Knippenberg F. C. E. van The quality of life of cancer patients: a review of the literature. Sot. Sci. Med. 20, 809-817, 1985. 6. Dam F. S. A. M. van, Linssen A. C. G., Engelsman E., Benthem J. van and Hanewald G. J. F. P. Life with cytostatic drugs. Eur. J. Cancer Suppl. 1.229-233, 1980. 7. Cassileth B. R., Lusk E. J. and Tenaglia A. N. A psychological comparison of patients with malignant melanomas and other dermatological diseases. Am. Acad. Dermat. 7, 742-746, 1982. 8. Cassileth B. R., Lusk E. J., Strouse T. B., Miller D. S., Brown L. L.. Cross P. A. and Tenaalia A. N. Psychological status in chronic illness: a comparative analysis of six diagnostic groups. N. Engl. J. Med. 311,506-51 I, 1984. 9. Craig T. J. and Abeloff M. D. Psychiatric symptomatology among hospitalized cancer patients. Am. J. Psychiat. 131, 1323-1327, 1974.

Underreporting 10. Plumb M. M: and Holland J. Comparative studies of psychological function in patients with advanced cancer-1. Self reported depressive symptoms. Psychosomatic Med. 39, 264-216, 1977. 11. Renneker R. and Cutler M. Psychosocial problems of adjustment to cancer of the breast. JAMA l&833-839, 1952. 12. Bard M. and Sutherland A. M. Psychological impact of cancer and its treatment. Cancer 8, 656-672, 1955. 13. Maguire G. P., Lee E. G., Bovington D. J., Kiichemann C. S., Crabtree R. J. and Cornell C. E. Psychiatric problems in the first year after mastectomy. Er. Med. J. 1, 963-965, 1978. 14. Cameron P., Titus D. G., Kostin J. and Kostin M. The life satisfaction of nonnormal persons. J. Consult. c/in. Psychol. 41, 207-214, 1973. 15. Brickman P., Coates D. and Janoff-Bulman R. Lottery winners and accident victims: is happiness relative? J. Person. Sot. Psychol. 36, 917-927, 1978. 16. Gutek B. A. Strategies for studying client satisfaction. J. Sot. Issues 34, 44-56,

1978.

17. Mowinsky, Jennings B. and Muhlenkamp A. F. Systematic misperception: oncology patients self-reported affective states and their caregivers’ perceptions. Cancer Nursing 4, 484-489, 1981. 18. Trimbos K. Mensen mer kanker. Van Loghum Slaterus, Deventer, 1978. 19. Hughes J. E. Denial in cancer patients. In Coping with Cancer Stress (Edited by Stoll B. A.). M. Nijhoff, Dordrecht, 1986. 20. Bahnson C. B. and Bahnson M. B. Role of the egodefenses: denial and repression in the etiology of malignant neoplasm. Annals of New York Academy of Sciences 125, 827-855, 1966. 21. Watson M., Greer S., Blake S. and Shrapnel1 K. Reaction to a diagnosis of breast cancer: relationship between denial, delay, and rates of psychological morbidity. Cancer 53, 2008-2012, 1984. 22. Helson H. Adapfafion Level Theory. Harper & Row, New York, 1964. 23. Festinger L. A theory of social comparison processes. Human Relations 7, 117-140, 1954. 24. Gruder Ch. L. Choice of comparison persons in evaluating oneself. In Social Comparison Processes (Edited by

byr cancer patients

987

Suls J. M. and Miller R. L.). Hemisphere Publishing Company, Washington, 1977. 25. Borne H. W. van den and Pruyn J. F. A. Lotgenoren conracr bij kankerparienten. Van Gorkum, Assen, 1985. 26. Molleman E., Pruyn J. and Knippenberg A. van. Social comparison processes among cancer patients. Br. J. Sot. Psycho/. 25, l-13, 1986. 27. Taylor S. E. Adjustment to threatening events, a theory of cognitive adaptation. Am. Psychol. 1161-1173, 1983. 28. Wills T. A. Downward comparison principles in social psychology. Psycholog. Bull: 90, 245-271; 1981. 29. Tavlor S. E. Social cognition and health. Person. sot. Psjchol. Bull. 8, 549-562, 1982. 30. Cook T. D. and Campbell D. T. Quasi-Experimentation: Design and Analysis Issues for Field Serrings.

Rand McNally, Chicago, 1979. 31. Cronbach L. J. and Furby L. How should we measure “change”-or should we? Psycholog. Bull. 74, 68-80, 1976. 32. Hoogstraten

J. Influence of objective measures on selfreports in a retrospective pretest-posttest design. J. exp.

Educ. 53, 207, 1985. 33. Terborg J. R., Howard

G. S. and Maxwell S. E. Evaluating planned organizational change: a method for assessing alpha, beta, and gamma change. Acad.

Management Rev. 5, W-121, 1980. 34. Golembiewsky R. T., Billingsley K. and Yeager S.

Measuring change and persistence in human affairs: types of change generated by OD designs. J. appl. Behao. Sci. 12, 133-157, 1976. 35. Howard G. S., Schmeck R. R. and Bray J. H. Internal

invalidity in studies employing self-report instruments: a suggested remedy. J. educ. Measurement 16, 129-135, 1979. 36. Huisman H. Physical-mentalpreferences: A study of rhe healrh stare preferences of cancer parienrs and blood donors (in Dutch). Doctoral thesis, internal publication

Psychological Laboratory, University of Amsterdam, 1984. 37. O’Connor A. M. Effects of framing and level of probability on patients’ preference for cancer chemotherapy. J. clin. Epidem. 42, 119-126, 1989.