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Changes in physical functioning and quality of life in patients with cancer
Journal of Clinical Epidemiology 55 (2002) 176–183
Changes in physical functioning and quality of life in patients with cancer Response shift and relative evaluation of one’s condition Mariët Hagedoorna,b,*, Kommer C.A. Sneeuwc, Neil K. Aaronsond a
Northern Centre for Healthcare Research and bDepartment of Public Health and Health Psychology, University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands c TNO Prevention and Health, Leiden, The Netherlands d Division of Psychosocial Research and Epidemiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands Received 6 March 2001; received in revised form 9 July 2001; accepted 30 July 2001
Abstract This study examined the hypothesis that patients’ persistence in comparing themselves with others who are perceived as being worse off might induce a response shift in self-reported quality of life (QL). Specifically, we tested whether patients’ ratings of how they are doing compared to others (i.e., relative evaluation) moderates the link between physical deterioration and decline in self-reported QL. Two hundred forty patients with various cancer diagnoses who were undergoing palliative chemotherapy rated their physical functioning and QL (i.e., emotional functioning and global quality of life) twice with an interval of 3 months. In addition, a significant other and a research assistant rated the physical condition of the patients. Consistent with the buffering model of response shift, patients who felt that they were better off than others appeared to be able to sustain their quality of life in the face of a worsening physical condition. In contrast, those who felt the same or worse off than others could not. © 2002 Elsevier Science Inc. All rights reserved. Keywords: Cancer patients; Physical functioning; Emotional functioning; Global quality of life; Relative evaluation; Response shift
1. Introduction Counterintuitively, people suffering from a life-threatening illness such as cancer often report relatively high and stable levels of overall quality of life (QL) and emotional well-being [1,2]. In a number of studies, cancer patients have reported levels of QL that were as high as those of less severely ill patients or of individuals from the general population [3–6]. Similarly, although prevalence rates vary considerably across studies, a meta-analysis by Van’t Spijker, Trijsburg, and Duivenvoorden [7] indicated that patients with cancer are not significantly more anxious or distressed than reference groups drawn from the general population. Current theory and research on the association between stressful events and indicators of well-being suggest that individuals may use a number of cognitive and behavioral strategies to counteract the negative impact of disease on their sense of well-being [8]. Important in this respect may be the “response shift phenomenon” [9,10]. A response shift in QL is defined as a change in the meaning of an individual’s self-reported QL. High levels of self-reported QL at
* Corresponding author. Tel.: 31 50 3633171; fax: 31 50 3632406. E-mail address: [email protected] (M. Hagedoorn)
different points in time may have different meanings. For example, a patient recently diagnosed with cancer may feel that her quality of life would be seriously compromised if she were no longer able to walk without assistance. However, at a later, more progressive stage of illness, the same patient may undergo a shift in her internal standards of measurement such that limitations in mobility are viewed as less important, and that her QL would be substantially affected only if she were to experience severe, chronic pain or other very debilitating symptoms. A response shift may reflect: (a) a change in one’s internal standards of measurement (i.e., scale recalibration in psychometric terms: the meaning of the scale anchors have changed), (b) a change in the importance attributed to component domains constituting QL (i.e., change in values and life goals), or (c) a redefinition of QL (i.e., reconceptualization) [9,10]. A study by Lepore and Eton [11] among men with prostate cancer provided support for a buffering model of response shift, that is, a protective or mitigating role of response shift. Scale recalibration and changes in values were found to mitigate the relationship between negative changes in physical health and negative changes in QL. More specifically, deterioration over time in urinary functioning was not associated with decline in QL if patients made a positive
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recalibration (i.e., expanded the scale of measurement to include worse outcomes), changed their life goals, or both. The present study was undertaken to explore further the psychological mechanisms that may be involved in producing a response shift. Recently, Sprangers and Schwartz [10] have proposed several such mechanisms, including social comparison processes. However, investigations into response shift as it relates to QL assessments are relatively new, and theory-driven studies are virtually nonexistent. Following Gibbons [12], we hypothesized that, in the face of deteriorating physical health, a sustained level of selfreported QL may reflect a response shift generated by patients’ perseverance in comparing themselves with others who are perceived as being worse off (i.e., downward comparison). It is assumed that a more positive relative evaluation in the face of a worsening physical condition indicates a larger response shift. If this assumption is true, the buffering model predicts that patients who feel better off than others are able to sustain their QL in the face of declining physical functioning, whereas those who feel the same or worse off than others are not. Wills [13] has proposed that individuals in threatening situations will often compare themselves with others who they believe to be worse off in an effort to sustain or improve their sense of well-being. Indeed, previous research suggests that individuals confronted with serious health problems tend to compare downward [14–18]. For example, about 80 % of the women with breast cancer interviewed in a study by Taylor, Wood, and Lichtman [16] reported they were doing “somewhat” or “much” better than other breast cancer patients. Taylor and her colleagues also found that, when patients did not have direct contact with or access to other patients, downward comparisons were still possible at a purely cognitive level. Schultz and Decker [19] suggest that even individuals with very serious health problems or disabilities are able to view themselves, on average, as being better off than most others by focusing selectively on personal attributes or circumstances that make them appear advantaged (e.g., intellectual capacity vs. physical strength; valued friendships vs. work performance). A number of previous studies have found downward comparison to be positively associated with positive feelings and adjustment to disease [14,17,20–23]. However, Major, Testa, and Bylsma [24] have hypothesized that downward comparison in uncontrollable situations may lead to negative instead of positive feelings, because the situation of the “comparison other” might be perceived as one’s own dreaded future. Patients with cancer have relatively little control over changes in their physical functioning, suggesting that downward comparison might be harmful instead of beneficial. Indeed, a number of studies suggests that cancer patients avoid potential downward comparison targets (i.e., patients who are worse off) [25– 27]. Taylor and Lobel [27] have suggested that, while cognitive comparison of one’s situation with that of others who are less fortunate might be comforting, face-to-face con-
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frontation with fellow patients who are worse off may actually increase feelings of discomfort [28]. The present study focuses on patients’ rating of how they are doing in comparison to others in a similar situation (i.e., cognitively generated relative evaluation), and not comparisons based on face-to-face contacts. How might downward evaluative comparison be involved in a response shift? When a comparison target no longer evokes a positive self-evaluation, patients may focus on another target that does, or may try to imagine someone who is worse off. Indeed, there is some evidence that people change their comparison targets when a threat becomes more severe (e.g., when their physical health deteriorates) [12]. From a response shift perspective, this implies that patients may, over time, expand the internal scale on which they evaluate their QL to account for worse outcomes. To summarize, the present study was undertaken to investigate whether persistence in downward social comparison is a mechanism that might produce a response shift. We focused on patients’ rating of how they are doing compared to others in a similar situation. Although such ratings do not tap directly into the process of social comparison (i.e., the cognitive or psychological mechanisms by which one arrives at a relative comparison), they do represent a measure of the outcome of that process (e.g., “I am better off than others in a similar situation”). Based on the buffering model of response shift, we hypothesized that patients who feel (much) better off than others are able to sustain their emotional well-being and global QL in the face of a declining physical functioning, whereas those who feel the same or worse off than others are not. In statistical terms, we expected that the correlation between change in physical functioning, on the one hand, and change in emotional well-being and global QL, on the other, would be weaker when the relative evaluation is more positive.
2. Methods 2.1. Study sample and procedures The present study was part of a larger investigation of the potential value and limitations of proxies in evaluating the QL of patients with cancer [29]. The study sample included patients with a range of cancer diagnoses who, during the period between November 1993 and September 1995, received chemotherapy at The Netherlands Cancer Institute/ Antoni van Leeuwenhoek Hospital. Patients were recruited from both the outpatient clinic or the clinical wards. Exclusion criteria were participation in a concurrent QL study, receiving adjuvant chemotherapy, age less than 18 years, and a lack of basic proficiency in Dutch. Eligible patients received a full verbal and written explanation of the purpose and procedures of the study. Consenting patients were requested to identify a significant other and to ask him or her to participate in the study. The significant others were also provided with verbal and written information about the
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study. The institutional review board of the hospitalapproved the study. The patients and their significant others completed questionnaires twice. The first assessment took place during the second (for inpatients) or third (for outpatients) cycle of chemotherapy (T1). The follow-up assessment was carried out approximately 3 months later (T2). Both administrations took place during patients’ visits to the outpatient clinic or during clinical ward stays. The significant other was asked to fill out the questionnaire in a separate room. Research assistants were present to answer questions and to check for missing data. When the significant other could not be approached at the hospital, the questionnaire was given to the patient for the significant other to complete at home. In these cases, the patients and significant others received explicit instructions not to discuss the questions with each other. Self-addressed, prestamped envelopes were provided for return of the questionnaires, and telephone reminders were used occasionally to maximize the response rate. 2.2. Study measures 2.2.1. Physical functioning Three different raters were asked to assess the patients’ physical functioning: the patients themselves, their significant others, and research staff. This facilitated replicating the key analyses based on independent ratings of physical health. Consistency of findings across information sources was considered additional evidence of the robustness of the study. Both the patients and their significant others were asked to complete the five-item physical functioning scale of the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ-C30), version 2.0 [30,31]. The items are: (1) do you have any trouble doing strenuous activities, like carrying a heavy shopping bag or a suitcase? (2) Do you have any trouble taking a long walk? (3) Do you have any trouble taking a short walk outside of the house? (4) Do you have to stay in bed or a chair for most of the day? (5) Do you need help with eating, dressing, washing yourself or using the toilet? (1 yes and 2 no). The significant others were asked to try to view the situation from the patients’ perspective, and to complete the questionnaires accordingly. Internal reliability of the scale was satisfactory at both assessments and for patients as well as significant others (Cronbach’s alpha varied from 0.69 and 0.72). In addition, for most patients, research assistants completed four questions assessing the patients’ physical functioning based on the components of the ECOG performance status scale [32]. Specifically, they rated the degree to which the patients experienced difficulty: (1) doing household chores or performing daily activities, (2) with personal care tasks, such as washing themselves, and (3) with walking (1 no, 2 yes, a little, 3 yes, a lot). They also rated the amount of time during waking hours patients had to spend in bed or in a chair due to their health (1 less than
half, 2 more than half, 3 all of the time). Internal reliability of this scale was satisfactory at both assessments (Cronbach’s alpha was 0.73 and and 0.76, respectively). For all three physical functioning measures, sum scores were linearly transformed to a 0 to 100 scale, with higher scores representing higher levels of functioning. 2.2.2. Emotional functioning and global QL Emotional functioning and global QL were measured with multi-item scales of the EORTC QLQ-C30. The emotional functioning scale consists of four items that assess generalized distress experienced during the past week, including indicators of both depressive mood and anxiety (i.e., worried, irritable, depressed, and tense). The response options range from (1) not at all to (4) very much . The internal consistency of the scale was 0.85 at T1, and 0.83 at T2. The global QL subscale consists of two items that ask patients to rate their overall health and their overall quality of life during the past week on a seven-point response scale ranging from 1 very poor to 7 excellent. The internal consistency of the global QL scale was high at both assessments ( 0.85 at T1, and 0.88 at T2). Scale scores were linearly converted to a 100-point scale, with higher scores representing better emotional functioning and QL. 2.2.3. Relative evaluation At follow-up, the relative evaluation item read: “When you compare yourself to other people in a similar situation, how would you say you are doing?” The response choices ranged on a seven-point scale from 1 much worse through 4 the same to 7 much better. 2.2.4. Background variables At T1, patients’ socio-demographic data (i.e., age, sex, marital status, education, and employment status) and clinical data (i.e., stage of the disease, weight loss in the past 2 months and comorbidity) were recorded. Because people tend to view social comparison as socially undesirable, the SDRS-5 [33], a five-item scale derived from the Marlowe-Crowne scale [34], was used to assess the patients’ tendency to answer questions in such a way as to represent themselves favorably (i.e., socially desirable response set). For example, patients were asked to indicate their agreement with the statement “I am always courteous, even to people who are disagreeable.” Extreme positive responses on a five-point response scale were summed. The internal consistency of this scale, which was filled out at T1, was 0.74. 2.3. Data analysis Change scores for physical functioning, emotional functioning, and global QL were computed by subtracting T1 scores from T2 scores. For physical functioning, separate change scores were calculated based on patients’, significant others’, and research assistants’ ratings. Positive change scores indicate improvements in physical functioning, emotional functioning, and global QL.
M. Hagedoorn et al. / Journal of Clinical Epidemiology 55 (2002) 176–183
The hypothesized buffering effect of relative evaluation was examined by means of linear regression analysis. Specifically, change scores for the emotional functioning and global QL scales were regressed on change scores for the physical functioning scale, the relative evaluation item, and the cross product of these two independent variables. To avoid multicollinearity between the predictors and the interaction terms, the multiplicative functions were computed as the products of the “centered” scores (i.e., centered around zero: score minus mean score) on the component variables [35,36]. Separate regression analyses were carried out for each of the three physical change indexes. Significant interactions were plotted as an aid in determining whether the observed effects were consistent with the buffering hypothesis. Specifically, as suggested by Aiken and West [35], simple regression lines were drawn of the interaction at two different levels of relative evaluation: one standard deviation above and one standard deviation below the mean, and the statistical significance of the separate slopes was calculated.
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that they did not know anyone with whom they could compare themselves. Patients who did not answer the relative evaluation question did not differ significantly from those who did with respect to physical functioning, emotional functioning, or global QL at either of the assessment points. There were also no significant differences observed between those who did and did not respond to this question on the change indexes or the social desirability scale. Table 1 presents the characteristics of the final sample study. There were slightly more female than male patients (55 and 45%, respectively). The average age of the patients was 50.5 years, and the majority was married (76%). All patients were undergoing chemotherapy on either an outpatient (67%) or inpatient (33%) basis. The most prevalent diagnoses were advanced breast cancer, gastrointestinal cancer, lymphomas, genitourinary cancer, lung cancer, and gynecological cancer. Seventy-two percent of the significant others
Table 1 Descriptive characteristics of patients (N 193)
3. Results 3.1. Sample characteristics Of 378 eligible patients (263 outpatients and 115 inpatients) 320 agreed to participate in the study (85% response rate). Of the 58 nonrespondents, 29 patients chose not to participate in the study due to very poor physical or emotional condition, and the remaining 29 patients reported not being interested or not having sufficient time. Of the 320 patients who completed the first assessment, 9 patients did not have or did not want to ask a significant other to take part in the study and 4 significant others chose not to participate in the study. Thus, at the first assessment, proxyderived ratings were obtained for 307 patients (96%). There were 80 patients lost to follow-up due to death (49%), too great a physical or emotional burden (32%), lack of interest or time (12%), or logistical problems (7%). Accordingly, at baseline, patients who were lost to follow-up reported a poorer physical functioning [mean 49.3, SD 29.0 vs. mean 68.3, SD 26.3, F(1, 318) 29.94, P .001] and a lower overall QL [mean 52.5, SD 22.1 vs. mean 66.7, SD 21.2, F(1, 315) 25.93, P .001] than those who remained in the study. These two groups did not differ with respect to emotional functioning. The significant others of those patients who were lost to follow-up were not asked to complete a second questionnaire. Additionally, 16 significant others were lost to follow-up because they were no longer available or unwilling to participate. In summary, T1 as well as T2 assessments were available for 240 patients and 224 significant others. Forty-seven (19.6%) of the 240 patients who completed both the first and the follow-up assessment did not answer the relative evaluation question. A number of participants stated that they did not wish to make such comparisons or
Characteristics Sex Female Male Age (years) Mean SD/range Marital status Married Divorced Widowed Unmarried Education Primary school Secondary school Advanced training University level Job No On sick leave Yes, part-time Yes, full-time Treatment Inpatient Outpatient Metastases Yes No Most prevalent diagnoses Advanced breast cancer Gastrointestinal tumors Lymphomas Genitourinary cancer Lung cancer Gynecological cancers Comorbidity Absent 1 Disease Weight loss None 10% 10%
Number
%
107 86
55 45
50.5 14.4
19–80
147 10 6 29
76 5 3 16
16 99 57 21
8 51 30 11
99 48 22 22
52 25 11.5 11.5
64 129
33 67
140 53
72.5 27.5
53 30 32 16 15 12
28 16 17 8 8 6
104 89
54 46
123 47 22
64 24.5 11.5
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6.98, P .01, b .17. In line with our predictions, the feeling that one is doing (much) better compared to others appears to sustain patients’ emotional functioning in the face of a worsening physical condition. As can be seen in Figure 1, among patients who felt they were doing (much) better compared to others in a similar situation, no significant association was observed between change in physical functioning and change in emotional functioning. In contrast, among those who felt the same or worse off than others, a decline in physical functioning was associated significantly with a decline in emotional functioning. In the second test of the buffering model, we examined whether the association between change in physical condition and change in global QL was moderated by the degree to which patients felt better off than others in a similar situation. The analyses based on the different indexes of change in physical functioning (i.e., patients’, significant others’, and research assistants’ ratings) all revealed significant twoway interactions. The two-way interaction parameter was Fch(1, 189) 10.54, b .15, P .01 based on the patients’ ratings, Fch(1, 177) 9.37, b .12, P .01 based on the ratings of the significant others, and Fch(1, 158) 4.63, b .14, P .05 based on the research assistants’ ratings. As can be seen in Figure 2 (based on the research assistants’ ratings) no association was observed between change in physical functioning and change in global QL among those patients who reported that they were doing much better compared to others in a similar situation. In contrast, among those who felt the same or worse off than others, a decline in physical functioning was associated significantly with a decline in global QL. The pattern of interaction was the same when using patients’ and significant others’ ratings of change in physical functioning.
Table 2 Scores on physical functioning, emotional functioning and QL at T1 and T2 T1 Variables Physical functioning Patients’ ratings Significant others’ ratings Research assistants’ ratings QL Emotional functioning Global QL
T2
Mean
SD
Mean
SD
Range
n
69.7
26.5
67.4
27.2
0–100
193
64.1
27.0
62.8
27.3
0–100
181
75.9
19.9
72.9
20.3
12.5–100
162
76.3 67.6
21.0 21.2
77.6 65.7
19.6 21.3
0–100 0–100
193 193
were spouses, 21% relatives, and 7% close friends. The large majority of the significant others (87%) reported having daily contact with the patients. Table 2 presents the score distributions for the physical functioning, emotional functioning, and global QL scales. At both assessments, these scores were very similar at the group level. Table 3 reports the correlations, means, standard deviations, and score ranges for the variables under study. As expected, the different indexes of change in physical functioning were significantly correlated (rs: .43 to .60). Change in physical functioning was weakly to moderately associated with change in emotional functioning (rs: .15 to .24) and change in global QL (rs: .26 to .38). Furthermore, the better off patients felt relative to others, the more positive the change in global QL (r .28). Importantly, social desirability was unrelated to changes in physical and emotional functioning, change in global QL, and relative evaluation. 3.2. Test of the Buffering model In the first test of the buffering model, we examined whether the association between change in physical condition and change in emotional functioning was moderated by the degree to which patients felt better off than others in a similar situation. When the ratings of patients or those of significant others of change in patients’ physical functioning were used, only main effects were statistically significant. However, using the rating of the research assistants, a significant two-way interaction was observed, Fch(1, 158)
4. Discussion In this article we have argued that persistence in downward evaluative comparison when faced with decline in physical health may be one of the mechanisms that bring about a response shift [10,12]. The better off patients whose physical condition has worsened feel compared to others in a similar situation, the stronger the indication of a response shift. Consistent with the buffering model of response shift
Table 3 Correlations, means, and standard deviations for the variables under study Variables
2
3
4
5
6
7
Mean
SD
Range
1. Physical P 2. Physical S 3. Physical R 4. Emotional functioning 5. Global QL 6. Relative evaluation 7. Social desirability
.43***
.60*** .45***
.24** .15* .28***
.33*** .38*** .26** .38***
.13 .04 .09 .12 .28***
.06 .09 .15
.00 .04 .08
2.4
1.3
2.9 1.3
1.9 5.37 1.63
21.9 23.3 15.6 18.1 20.3 1.28 1.64
60–40
80–80
50–50
50–58
92–67 2–7 0–5
Note: change. P patients’ ratings; S significant others’ ratings; R research assistants’ ratings. *p .05; **p .01; ***p .001
M. Hagedoorn et al. / Journal of Clinical Epidemiology 55 (2002) 176–183
Fig. 1. The association between change in patients, physical functioning (T2–T1: research assistants’ ratings) and change in emotional functioning (T2–T1) as a function of relative evaluation. Note: “The same off as others” reflects a relative evaluation score of 1 SD below the mean. “Better off than others” reflects a relative evaluation score of 1 SD above the mean.
[11], the findings support the mitigating effect of patients’ positive relative evaluation. More specifically, patients who considered themselves (much) better off than others appeared to be able to sustain their QL in the face of a worsening physical functioning, whereas those who felt the same or worse off as others could not. The current study restricted itself to an examination of self-reported emotional functioning and global QL. This was done for several reasons. Most importantly, a number of previous studies have reported rather high and stable levels of emotional functioning and QL among cancer patients; a finding that runs contrary to clinical expectations, and that is suggestive of a response shift phenomenon. Second, it has been suggested that response shift is more likely to occur when patients are asked to rate those aspects of their health and functioning that are more subjective and less concrete [1,37]. Conversely, the more specific and concrete the health concept being rated, the less likely a response shift will occur. Indeed, additional exploratory analyses revealed no interaction between changes in physical functioning and patients’ relative evaluation on very concrete and specific symptoms, including anorexia, nausea/vomiting, diarrhea, and constipation. In a similar vein, previous research has indicated that people are more likely to feel better off when comparing themselves to others on relatively abstract attributes such as empathy or intuition, rather than on more concrete issues such as number of friends [38]. Third, other functioning measures, such as social (i.e., interference of physical condition or medical treatment with family and social life) and role (i.e., limitations with respect to work or other daily activities) functioning, are closely linked to physical functioning, and therefore, not as appropriate for studying response shift. Although fatigue and pain depend on patients’ physical condition, these aspects also include a subjective component, which may be susceptible to response shift. However, additional exploratory analyses did not indicate an interaction effect between changes in physical functioning and patients’ relative evaluation on these two aspects of QL.
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Fig. 2. The association between change in patients’ physical functioning (T2–T1: research assistants’ ratings) and change in global QL (T2–T1) as a function of relative evaluation. Note: “The same off as others” reflects a relative evaluation score of 1 SD below the mean. “Better off than others” reflects a relative evaluation score of 1 SD above the mean.
Support for the buffering effect of relative evaluation on self-reported global QL was consistent across all three indexes of change in physical functioning (based on patients’, significant others’, and research assistants’ ratings). For self-reported emotional functioning, evidence of the buffering effect of relative evaluation was found only when employing the change index for physical functioning based on the research assistants’ ratings. Although there is no clear explanation for this latter finding, it may be related in some way to differences in the way in which physical functioning was assessed by the various raters. The research staff did not complete the EORTC QLQ-C30, because it was not deemed feasible for them to respond to the detailed series of questions included in the questionnaire. It was possible for them to provide a more global rating of physical health using the ECOG performance status scale. Although the physical functioning subscale of the EORTC and the ECOG rating scales are similar, these scales are not identical in content, and thus are not strictly comparable. Although our results are consistent with theory, because we did not assess response shift directly, they do not provide unequivocal evidence that a positive relative evaluation results in a response shift in patients’ serial ratings of their emotional functioning and global QL. A frequently used technique for assessing response shift is to compare “then-test” scores (i.e., a renewed judgement of pretest level of QL at posttest) with pretest scores. Because the parent study was not directed at the issue of response shift, such then-test data were not available. However, a then-test also represents an indirect measure of response shift [39], and may be susceptible to recall bias. Sprangers and her colleagues [39] have recommended that different approaches to detecting response shift be compared. We would recommend that future studies be undertaken in which measures of social comparison behavior and the then-test technique are used as complementary approaches to assessing response shift in self-reported health status ratings. In our work we have assumed that patients’ relative evaluations represent the outcome of a social comparison pro-
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cess. It has been suggested that relative evaluations may simply reflect current health states, such as positive mood [40] or objectively defined physical functioning [41]. However, this is more likely to be of concern in cross-sectional studies, where direct links between patients’ positive relative evaluations and self-reported well-being are being investigated. Because the current study employed a longitudinal design, focused on changes in self-reported well-being, and tested a moderator model, this potential source of confounding may be less of a concern. Additionally, previous studies have reported positive correlations between frequency of downward comparison and positive evaluations of how well one is doing compared to others, suggesting that relative evaluations, at least in part, reflect social comparison processes [17,42]. Some of the patients in our sample declined to answer the relative evaluation question. Previous studies of individuals with serious health problems have reported a similar reluctance to make explicit social comparisons [19,43,44]. Such reticence might reflect a belief that such comparisons are socially undesirable, particularly when one rates oneself as being better off than others. However, we found no differences in scores on a measure of social desirability between those who did and did not complete the relative evaluation question. An alternative, and simpler explanation is that those individuals who did not provide a relative evaluation simply do not (or prefer not to) use this type of cognitive strategy [45]. In any case, completion of the relative evaluation item was unrelated to scores on the physical functioning, emotional functioning, and global QL measures. To our knowledge, this is the first longitudinal study investigating the buffering effect of a positive relative evaluation for cancer patients facing a decline in their physical health. Although our findings lend support to the buffering hypothesis, some caution needs to be introduced in generalizing our results to all patients with cancer. Approximately 15% of the eligible patients chose not to participate in the study, and approximately 25% of participating patients were lost to follow-up, primarily due to death or to the perceived physical or emotional burden of the study. In other words, the patients who faced the largest decline in health may not have been included in the study. Possibly, there is a limit to which the negative impact of declining physical health on QL can be counteracted by a positive relative evaluation. Additionally, the reversibility of the negative changes in physical health may be of importance. For example, it may be easier for patients to maintain a relatively high level of global QL when deteriorating physical health is due to the transient side effects of treatment. Future studies are needed to clarify these issues. The results of this study are not only of theoretical interest; they may have practical implications as well. Palliative cancer treatment is aimed at achieving tumor response and thus at lengthening survival. However, when objective improvement in health is no longer possible, cognitive and be-
havioral strategies may become increasingly important in mitigating the impact of disease progression on patients’ sense of well-being. As Wilson ([37], p. 1584) has stated: “When biological or physiological change is no longer possible (i.e., all ‘conventional’ therapies have been unsuccessfully tried), a principal goal of care might become the induction of scale recalibration, concept redefinition, or a change in values.” Consistent with the literature on response shift and on social comparison, the current results indicate that cognitive strategies that promote a patient’s sense of relative well-being are psychologically adaptive. This suggests that interventions aimed at facilitating the use of such cognitive techniques may be useful to patients and their families in learning to cope with the effects of cancer and its treatment on their daily lives.
References [1] Breetvelt IS, Van Dam FSAM. Underreporting by cancer patients: the case of response-shift. Soc Sci Med 1991;32:981–7. [2] De Haes JCJM, Van Knippenberg FCE. The quality of life of cancer patients: a review of the literature. Soc Sci Med 1985;20:809–17. [3] Andrykowski MA, Curran SL, Studts JL, Cunningham L, Carpenter JS, McGrath PC, Sloan DA, Kenady DE. Psychosocial adjustment and quality of life in women with breast cancer and benign breast problems: a controlled comparison. J Clin Epidemiol 1996;49:827–34. [4] Cassileth BR, Lusk EJ, Strouse TB, Miller DS, Brown LL, Cross PA, Tenaglia AN. Psychosocial status in chronic illness. A comparative analysis of six diagnostic groups. N Engl J Med 1984;311:506–11. [5] Lepore SJ, Helgeson VS. Social constraints, intrusive thoughts, and mental health after prostate cancer. J Soc Clin Psychol 1998;17:89–106. [6] Litwin MS, Hays RD, Fink A, Ganz PA, Leake B, Leach GE, Brook RH. Quality-of-life outcomes in men treated for localized prostate cancer [see comments]. JAMA 1995;273:129–135. [7] Van’t Spijker A, Trijsburg RW, Duivenvoorden HJ. Psychological sequelae of cancer diagnosis: a meta-analytical review of 58 studies after 1980. Psychosom Med 1997;59:280–293. [8] Folkman S, Lazarus RS, Gruen RJ, DeLongis A. Appraisal, coping, health status, and psychological symptoms. J Pers Soc Psychol 1986; 50:571–579. [9] Schwartz CE, Sprangers MAG. Methodological approaches for assessing response shift in longitudinal health-related quality-of-life research. Soc Sci Med 1999;48:1531–48. [10] Sprangers MAG, Schwartz CE. Integrating response shift into healthrelated quality of life research: a theoretical model. Soc Sci Med 1999;48:1507–15. [11] Lepore SJ, Eton DT. Response shifts in prostate cancer patients: an evaluation of suppressor and buffer models. In: Schwartz C, Sprangers MAG, editors. Adaptation to changing health: response shift in quality-of-life research. Washington, DC: American Psychological Association, 2000. p. 37–51. [12] Gibbons FX. Social comparison as a mediator of response shift. Soc Sci Med 1999;48:1517–30. [13] Wills TA. Downward comparison principles in social psychology. Psychol Bull 1981;90:245–71. [14] Affleck G, Tennen H, Pfeiffer C, Fifield J, Rowe J. Downward comparison and coping with serious medical problems. Am J Orthopsychiatry 1987;57:570–8. [15] [DeVellis R, Holt K, Renner B, Blalock SJ. The relationship of social comparison to rheumatoid arthritis symptoms and affect. Basic Appl Soc Psychol 1990;11:1–18. [16] Taylor SE, Wood JV, Lichtman RR. It could be worse: selective evaluation as a response to victimization. J Soc Issues 1983;39:19–40.
M. Hagedoorn et al. / Journal of Clinical Epidemiology 55 (2002) 176–183 [17] VanderZee KI, Buunk BP, DeRuiter JH, Tempelaar R, Van Sonderen E, Sanderman R. Social comparison and the subjective well-being of cancer patients. Basic Appl Soc Psychol 1996;18:453–68. [18] Wood JV, Taylor SE, Lichtman RR. Social comparison in adjustment to breast cancer. J Pers Soc Psychol 1985;49:1169–83. [19] Schulz R, Decker S. Long-term adjustment to physical disability: the role of social support, perceived control, and self-blame. J Pers Soc Psychol 1985;48:1162–72. [20] Affleck G, Tennen H. Social comparison and coping with major medical problems. In: Suls J, editor. Social comparison: contemporary theory and research. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc., 1991. p. 369–93. [21] Buunk BP, Collins RL, Taylor SE, VanYperen NW, Dakof GA. The affective consequences of social comparison: either direction has its ups and downs. J Pers Soc Psychol 1990;59:1238–49. [22] Taylor SE, Buunk BP, Aspinwall L. Social comparison, stress, and coping. Pers Soc Psychol Bull 1990;16:74–89. [23] Taylor SE, Brown JD. Illusion and well-being: a social psychological perspective on mental health. Psychol Bull 1988;103:193–210. [24] Major B, Testa M, Blysma WH. Responses to upward and downward social comparisons: the impact of esteem-relevance and perceived control. In: Suls J, editor. Social comparison: contemporary theory and research. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc., 1991. p. 237–60. [25] Dunkel-Shetter C, Wortman CB. The interpersonal dynamics of cancer: problems in social relationships and their impact on the patient. In: Friedman HS, DiMatteo MR, editors. Interpersonal issues in health care. Orlando, FL: Academic Press, 1982. p. 69–100. [26] Molleman E, Pruyn J, Van Knippenberg A. Social comparison processes among cancer patients. Br J Soc Psychol 1986;25:1–13. [27] Taylor SE, Lobel M. Social comparison activity under threat: downward evaluation and upward contacts. Psychol Rev 1989;96:569–75. [28] Stanton AL, Danoff-Burg S, Cameron CL, Snider PR, Kirk SB. Social comparison and adjustment to breast cancer: an experimental examination of upward affiliation and downward evaluation. Health Psychol 1999;18:151–8. [29] Sneeuw KCA, Aaronson NK, Sprangers MAG, Detmar SB, Wever LD, Schornagel JH. Comparison of patient and proxy EORTC QLQC30 ratings in assessing the quality of life of cancer patients. J Clin Epidemiol 1998;51:617–31. [30] Aaronson NK, Ahmedzai S, Bergman B, Bullinger M, Cull A, Duez NJ, Filiberti A, Flechtner H, Fleishman SB, De Haes JCJM. The European Organization for Research and Treatment of Cancer QLQC30: a quality-of-life instrument for use in international clinical trials in oncology. J Natl Cancer Inst 1993;85:365–76.
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[31] Osaba D, Aaronson NK, Zee B, Sprangers MAG, Te Veld A. Modification of the EORTC QLQ-C30 (version 2.0) based on content validity and reliability testing in large samples of patients with cancer. Qual Life Res 2000;6:103–8. [32] Conill C, Verger E, Salamero M. Performance status assessment in cancer patients. Cancer 1990;65:1864–6. [33] Hays R, Hayashi T, Stewart A. A five-item measure of socially desirable response set. Educ Psychol Meas 1989;49:629–36. [34] Marlowe DP, Crowne D. A new scale of social desirability independent of psychopathology. J Consult Psychol 1960;24:349–54. [35] Aiken LS, West SG. Multiple regression: testing and interpreting interactions. xi ed. Newbury Park, CA: Sage Publications, Inc., 1991. [36] Cohen J, Cohen P. Applied multiple regression/correlation analysis for the behavioral sciences. Hillsdale, NJ: Lawrence Erlbaum, 1975. p. 490, 1983. [37] Wilson IB. Clinical understanding and clinical implications of response shift. Soc Sci Med 1999;48:1577–88. [38] VanYperen NW. Self-enhancement among major league soccer players: the role of importance and ambiguity on social comparison behavior. J Appl Soc Psychol 1992;22:1186–98. [39] Sprangers MAG, Van Dam FSAM, Broersen J, Lodder L, Wever LDV, Visser MRM, Oosterveld P, Smets EMA. Revealing response shift in longitudinal research on fatigue—the use of the thentest approach. Acta Oncol 1999;38:709–18. [40] Wood JV, VanderZee K. Social comparisons among cancer patients: under what conditions are comparisons upward and downward? In: Buunk BP, Gibbons F, editors. Health, coping, and well-being: perspectives from social comparison theory. Mahwah, NJ: Lawrence Erlbaum Associates, Inc., 1997. p. 299–328. [41] Diener E, Fujita F. Social comparisons and subjective well-being. In: Buunk BP, Gibbons F, editors. Health, coping, and well-being: perspectives from social comparison theory. Mahwah, NJ: Lawrence Erlbaum Associates, Inc., 1997. p. 329–57. [42] VanderZee KI, Buunk BP, Sanderman R. Social comparison as a mediator between health problems and subjective health evaluations. Br J Soc Psychol 1995;34:53–65. [43] Helgeson VS, Taylor SE. Social comparisons and adjustment among cardiac patients. J Appl Soc Psychol 1993;23:1171–95. [44] Hemphill K, Lehman DR. Social comparisons and their affective consequences: the importance of comparison dimension and individual difference variables. J Soc Clin Psychol 1991;10:372–94. [45] Gibbons FX, Buunk BP. Individual differences in social comparison: development of a scale of social comparison orientation. J Pers Soc Psychol 1999;76:129–42.
Changes in physical functioning and quality of life in patients with cancer Response shift and relative evaluation of one’s condition Mariët Hagedoorna,b,*, Kommer C.A. Sneeuwc, Neil K. Aaronsond a
Northern Centre for Healthcare Research and bDepartment of Public Health and Health Psychology, University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands c TNO Prevention and Health, Leiden, The Netherlands d Division of Psychosocial Research and Epidemiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands Received 6 March 2001; received in revised form 9 July 2001; accepted 30 July 2001
Abstract This study examined the hypothesis that patients’ persistence in comparing themselves with others who are perceived as being worse off might induce a response shift in self-reported quality of life (QL). Specifically, we tested whether patients’ ratings of how they are doing compared to others (i.e., relative evaluation) moderates the link between physical deterioration and decline in self-reported QL. Two hundred forty patients with various cancer diagnoses who were undergoing palliative chemotherapy rated their physical functioning and QL (i.e., emotional functioning and global quality of life) twice with an interval of 3 months. In addition, a significant other and a research assistant rated the physical condition of the patients. Consistent with the buffering model of response shift, patients who felt that they were better off than others appeared to be able to sustain their quality of life in the face of a worsening physical condition. In contrast, those who felt the same or worse off than others could not. © 2002 Elsevier Science Inc. All rights reserved. Keywords: Cancer patients; Physical functioning; Emotional functioning; Global quality of life; Relative evaluation; Response shift
1. Introduction Counterintuitively, people suffering from a life-threatening illness such as cancer often report relatively high and stable levels of overall quality of life (QL) and emotional well-being [1,2]. In a number of studies, cancer patients have reported levels of QL that were as high as those of less severely ill patients or of individuals from the general population [3–6]. Similarly, although prevalence rates vary considerably across studies, a meta-analysis by Van’t Spijker, Trijsburg, and Duivenvoorden [7] indicated that patients with cancer are not significantly more anxious or distressed than reference groups drawn from the general population. Current theory and research on the association between stressful events and indicators of well-being suggest that individuals may use a number of cognitive and behavioral strategies to counteract the negative impact of disease on their sense of well-being [8]. Important in this respect may be the “response shift phenomenon” [9,10]. A response shift in QL is defined as a change in the meaning of an individual’s self-reported QL. High levels of self-reported QL at
* Corresponding author. Tel.: 31 50 3633171; fax: 31 50 3632406. E-mail address: [email protected] (M. Hagedoorn)
different points in time may have different meanings. For example, a patient recently diagnosed with cancer may feel that her quality of life would be seriously compromised if she were no longer able to walk without assistance. However, at a later, more progressive stage of illness, the same patient may undergo a shift in her internal standards of measurement such that limitations in mobility are viewed as less important, and that her QL would be substantially affected only if she were to experience severe, chronic pain or other very debilitating symptoms. A response shift may reflect: (a) a change in one’s internal standards of measurement (i.e., scale recalibration in psychometric terms: the meaning of the scale anchors have changed), (b) a change in the importance attributed to component domains constituting QL (i.e., change in values and life goals), or (c) a redefinition of QL (i.e., reconceptualization) [9,10]. A study by Lepore and Eton [11] among men with prostate cancer provided support for a buffering model of response shift, that is, a protective or mitigating role of response shift. Scale recalibration and changes in values were found to mitigate the relationship between negative changes in physical health and negative changes in QL. More specifically, deterioration over time in urinary functioning was not associated with decline in QL if patients made a positive
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recalibration (i.e., expanded the scale of measurement to include worse outcomes), changed their life goals, or both. The present study was undertaken to explore further the psychological mechanisms that may be involved in producing a response shift. Recently, Sprangers and Schwartz [10] have proposed several such mechanisms, including social comparison processes. However, investigations into response shift as it relates to QL assessments are relatively new, and theory-driven studies are virtually nonexistent. Following Gibbons [12], we hypothesized that, in the face of deteriorating physical health, a sustained level of selfreported QL may reflect a response shift generated by patients’ perseverance in comparing themselves with others who are perceived as being worse off (i.e., downward comparison). It is assumed that a more positive relative evaluation in the face of a worsening physical condition indicates a larger response shift. If this assumption is true, the buffering model predicts that patients who feel better off than others are able to sustain their QL in the face of declining physical functioning, whereas those who feel the same or worse off than others are not. Wills [13] has proposed that individuals in threatening situations will often compare themselves with others who they believe to be worse off in an effort to sustain or improve their sense of well-being. Indeed, previous research suggests that individuals confronted with serious health problems tend to compare downward [14–18]. For example, about 80 % of the women with breast cancer interviewed in a study by Taylor, Wood, and Lichtman [16] reported they were doing “somewhat” or “much” better than other breast cancer patients. Taylor and her colleagues also found that, when patients did not have direct contact with or access to other patients, downward comparisons were still possible at a purely cognitive level. Schultz and Decker [19] suggest that even individuals with very serious health problems or disabilities are able to view themselves, on average, as being better off than most others by focusing selectively on personal attributes or circumstances that make them appear advantaged (e.g., intellectual capacity vs. physical strength; valued friendships vs. work performance). A number of previous studies have found downward comparison to be positively associated with positive feelings and adjustment to disease [14,17,20–23]. However, Major, Testa, and Bylsma [24] have hypothesized that downward comparison in uncontrollable situations may lead to negative instead of positive feelings, because the situation of the “comparison other” might be perceived as one’s own dreaded future. Patients with cancer have relatively little control over changes in their physical functioning, suggesting that downward comparison might be harmful instead of beneficial. Indeed, a number of studies suggests that cancer patients avoid potential downward comparison targets (i.e., patients who are worse off) [25– 27]. Taylor and Lobel [27] have suggested that, while cognitive comparison of one’s situation with that of others who are less fortunate might be comforting, face-to-face con-
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frontation with fellow patients who are worse off may actually increase feelings of discomfort [28]. The present study focuses on patients’ rating of how they are doing in comparison to others in a similar situation (i.e., cognitively generated relative evaluation), and not comparisons based on face-to-face contacts. How might downward evaluative comparison be involved in a response shift? When a comparison target no longer evokes a positive self-evaluation, patients may focus on another target that does, or may try to imagine someone who is worse off. Indeed, there is some evidence that people change their comparison targets when a threat becomes more severe (e.g., when their physical health deteriorates) [12]. From a response shift perspective, this implies that patients may, over time, expand the internal scale on which they evaluate their QL to account for worse outcomes. To summarize, the present study was undertaken to investigate whether persistence in downward social comparison is a mechanism that might produce a response shift. We focused on patients’ rating of how they are doing compared to others in a similar situation. Although such ratings do not tap directly into the process of social comparison (i.e., the cognitive or psychological mechanisms by which one arrives at a relative comparison), they do represent a measure of the outcome of that process (e.g., “I am better off than others in a similar situation”). Based on the buffering model of response shift, we hypothesized that patients who feel (much) better off than others are able to sustain their emotional well-being and global QL in the face of a declining physical functioning, whereas those who feel the same or worse off than others are not. In statistical terms, we expected that the correlation between change in physical functioning, on the one hand, and change in emotional well-being and global QL, on the other, would be weaker when the relative evaluation is more positive.
2. Methods 2.1. Study sample and procedures The present study was part of a larger investigation of the potential value and limitations of proxies in evaluating the QL of patients with cancer [29]. The study sample included patients with a range of cancer diagnoses who, during the period between November 1993 and September 1995, received chemotherapy at The Netherlands Cancer Institute/ Antoni van Leeuwenhoek Hospital. Patients were recruited from both the outpatient clinic or the clinical wards. Exclusion criteria were participation in a concurrent QL study, receiving adjuvant chemotherapy, age less than 18 years, and a lack of basic proficiency in Dutch. Eligible patients received a full verbal and written explanation of the purpose and procedures of the study. Consenting patients were requested to identify a significant other and to ask him or her to participate in the study. The significant others were also provided with verbal and written information about the
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study. The institutional review board of the hospitalapproved the study. The patients and their significant others completed questionnaires twice. The first assessment took place during the second (for inpatients) or third (for outpatients) cycle of chemotherapy (T1). The follow-up assessment was carried out approximately 3 months later (T2). Both administrations took place during patients’ visits to the outpatient clinic or during clinical ward stays. The significant other was asked to fill out the questionnaire in a separate room. Research assistants were present to answer questions and to check for missing data. When the significant other could not be approached at the hospital, the questionnaire was given to the patient for the significant other to complete at home. In these cases, the patients and significant others received explicit instructions not to discuss the questions with each other. Self-addressed, prestamped envelopes were provided for return of the questionnaires, and telephone reminders were used occasionally to maximize the response rate. 2.2. Study measures 2.2.1. Physical functioning Three different raters were asked to assess the patients’ physical functioning: the patients themselves, their significant others, and research staff. This facilitated replicating the key analyses based on independent ratings of physical health. Consistency of findings across information sources was considered additional evidence of the robustness of the study. Both the patients and their significant others were asked to complete the five-item physical functioning scale of the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ-C30), version 2.0 [30,31]. The items are: (1) do you have any trouble doing strenuous activities, like carrying a heavy shopping bag or a suitcase? (2) Do you have any trouble taking a long walk? (3) Do you have any trouble taking a short walk outside of the house? (4) Do you have to stay in bed or a chair for most of the day? (5) Do you need help with eating, dressing, washing yourself or using the toilet? (1 yes and 2 no). The significant others were asked to try to view the situation from the patients’ perspective, and to complete the questionnaires accordingly. Internal reliability of the scale was satisfactory at both assessments and for patients as well as significant others (Cronbach’s alpha varied from 0.69 and 0.72). In addition, for most patients, research assistants completed four questions assessing the patients’ physical functioning based on the components of the ECOG performance status scale [32]. Specifically, they rated the degree to which the patients experienced difficulty: (1) doing household chores or performing daily activities, (2) with personal care tasks, such as washing themselves, and (3) with walking (1 no, 2 yes, a little, 3 yes, a lot). They also rated the amount of time during waking hours patients had to spend in bed or in a chair due to their health (1 less than
half, 2 more than half, 3 all of the time). Internal reliability of this scale was satisfactory at both assessments (Cronbach’s alpha was 0.73 and and 0.76, respectively). For all three physical functioning measures, sum scores were linearly transformed to a 0 to 100 scale, with higher scores representing higher levels of functioning. 2.2.2. Emotional functioning and global QL Emotional functioning and global QL were measured with multi-item scales of the EORTC QLQ-C30. The emotional functioning scale consists of four items that assess generalized distress experienced during the past week, including indicators of both depressive mood and anxiety (i.e., worried, irritable, depressed, and tense). The response options range from (1) not at all to (4) very much . The internal consistency of the scale was 0.85 at T1, and 0.83 at T2. The global QL subscale consists of two items that ask patients to rate their overall health and their overall quality of life during the past week on a seven-point response scale ranging from 1 very poor to 7 excellent. The internal consistency of the global QL scale was high at both assessments ( 0.85 at T1, and 0.88 at T2). Scale scores were linearly converted to a 100-point scale, with higher scores representing better emotional functioning and QL. 2.2.3. Relative evaluation At follow-up, the relative evaluation item read: “When you compare yourself to other people in a similar situation, how would you say you are doing?” The response choices ranged on a seven-point scale from 1 much worse through 4 the same to 7 much better. 2.2.4. Background variables At T1, patients’ socio-demographic data (i.e., age, sex, marital status, education, and employment status) and clinical data (i.e., stage of the disease, weight loss in the past 2 months and comorbidity) were recorded. Because people tend to view social comparison as socially undesirable, the SDRS-5 [33], a five-item scale derived from the Marlowe-Crowne scale [34], was used to assess the patients’ tendency to answer questions in such a way as to represent themselves favorably (i.e., socially desirable response set). For example, patients were asked to indicate their agreement with the statement “I am always courteous, even to people who are disagreeable.” Extreme positive responses on a five-point response scale were summed. The internal consistency of this scale, which was filled out at T1, was 0.74. 2.3. Data analysis Change scores for physical functioning, emotional functioning, and global QL were computed by subtracting T1 scores from T2 scores. For physical functioning, separate change scores were calculated based on patients’, significant others’, and research assistants’ ratings. Positive change scores indicate improvements in physical functioning, emotional functioning, and global QL.
M. Hagedoorn et al. / Journal of Clinical Epidemiology 55 (2002) 176–183
The hypothesized buffering effect of relative evaluation was examined by means of linear regression analysis. Specifically, change scores for the emotional functioning and global QL scales were regressed on change scores for the physical functioning scale, the relative evaluation item, and the cross product of these two independent variables. To avoid multicollinearity between the predictors and the interaction terms, the multiplicative functions were computed as the products of the “centered” scores (i.e., centered around zero: score minus mean score) on the component variables [35,36]. Separate regression analyses were carried out for each of the three physical change indexes. Significant interactions were plotted as an aid in determining whether the observed effects were consistent with the buffering hypothesis. Specifically, as suggested by Aiken and West [35], simple regression lines were drawn of the interaction at two different levels of relative evaluation: one standard deviation above and one standard deviation below the mean, and the statistical significance of the separate slopes was calculated.
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that they did not know anyone with whom they could compare themselves. Patients who did not answer the relative evaluation question did not differ significantly from those who did with respect to physical functioning, emotional functioning, or global QL at either of the assessment points. There were also no significant differences observed between those who did and did not respond to this question on the change indexes or the social desirability scale. Table 1 presents the characteristics of the final sample study. There were slightly more female than male patients (55 and 45%, respectively). The average age of the patients was 50.5 years, and the majority was married (76%). All patients were undergoing chemotherapy on either an outpatient (67%) or inpatient (33%) basis. The most prevalent diagnoses were advanced breast cancer, gastrointestinal cancer, lymphomas, genitourinary cancer, lung cancer, and gynecological cancer. Seventy-two percent of the significant others
Table 1 Descriptive characteristics of patients (N 193)
3. Results 3.1. Sample characteristics Of 378 eligible patients (263 outpatients and 115 inpatients) 320 agreed to participate in the study (85% response rate). Of the 58 nonrespondents, 29 patients chose not to participate in the study due to very poor physical or emotional condition, and the remaining 29 patients reported not being interested or not having sufficient time. Of the 320 patients who completed the first assessment, 9 patients did not have or did not want to ask a significant other to take part in the study and 4 significant others chose not to participate in the study. Thus, at the first assessment, proxyderived ratings were obtained for 307 patients (96%). There were 80 patients lost to follow-up due to death (49%), too great a physical or emotional burden (32%), lack of interest or time (12%), or logistical problems (7%). Accordingly, at baseline, patients who were lost to follow-up reported a poorer physical functioning [mean 49.3, SD 29.0 vs. mean 68.3, SD 26.3, F(1, 318) 29.94, P .001] and a lower overall QL [mean 52.5, SD 22.1 vs. mean 66.7, SD 21.2, F(1, 315) 25.93, P .001] than those who remained in the study. These two groups did not differ with respect to emotional functioning. The significant others of those patients who were lost to follow-up were not asked to complete a second questionnaire. Additionally, 16 significant others were lost to follow-up because they were no longer available or unwilling to participate. In summary, T1 as well as T2 assessments were available for 240 patients and 224 significant others. Forty-seven (19.6%) of the 240 patients who completed both the first and the follow-up assessment did not answer the relative evaluation question. A number of participants stated that they did not wish to make such comparisons or
Characteristics Sex Female Male Age (years) Mean SD/range Marital status Married Divorced Widowed Unmarried Education Primary school Secondary school Advanced training University level Job No On sick leave Yes, part-time Yes, full-time Treatment Inpatient Outpatient Metastases Yes No Most prevalent diagnoses Advanced breast cancer Gastrointestinal tumors Lymphomas Genitourinary cancer Lung cancer Gynecological cancers Comorbidity Absent 1 Disease Weight loss None 10% 10%
Number
%
107 86
55 45
50.5 14.4
19–80
147 10 6 29
76 5 3 16
16 99 57 21
8 51 30 11
99 48 22 22
52 25 11.5 11.5
64 129
33 67
140 53
72.5 27.5
53 30 32 16 15 12
28 16 17 8 8 6
104 89
54 46
123 47 22
64 24.5 11.5
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6.98, P .01, b .17. In line with our predictions, the feeling that one is doing (much) better compared to others appears to sustain patients’ emotional functioning in the face of a worsening physical condition. As can be seen in Figure 1, among patients who felt they were doing (much) better compared to others in a similar situation, no significant association was observed between change in physical functioning and change in emotional functioning. In contrast, among those who felt the same or worse off than others, a decline in physical functioning was associated significantly with a decline in emotional functioning. In the second test of the buffering model, we examined whether the association between change in physical condition and change in global QL was moderated by the degree to which patients felt better off than others in a similar situation. The analyses based on the different indexes of change in physical functioning (i.e., patients’, significant others’, and research assistants’ ratings) all revealed significant twoway interactions. The two-way interaction parameter was Fch(1, 189) 10.54, b .15, P .01 based on the patients’ ratings, Fch(1, 177) 9.37, b .12, P .01 based on the ratings of the significant others, and Fch(1, 158) 4.63, b .14, P .05 based on the research assistants’ ratings. As can be seen in Figure 2 (based on the research assistants’ ratings) no association was observed between change in physical functioning and change in global QL among those patients who reported that they were doing much better compared to others in a similar situation. In contrast, among those who felt the same or worse off than others, a decline in physical functioning was associated significantly with a decline in global QL. The pattern of interaction was the same when using patients’ and significant others’ ratings of change in physical functioning.
Table 2 Scores on physical functioning, emotional functioning and QL at T1 and T2 T1 Variables Physical functioning Patients’ ratings Significant others’ ratings Research assistants’ ratings QL Emotional functioning Global QL
T2
Mean
SD
Mean
SD
Range
n
69.7
26.5
67.4
27.2
0–100
193
64.1
27.0
62.8
27.3
0–100
181
75.9
19.9
72.9
20.3
12.5–100
162
76.3 67.6
21.0 21.2
77.6 65.7
19.6 21.3
0–100 0–100
193 193
were spouses, 21% relatives, and 7% close friends. The large majority of the significant others (87%) reported having daily contact with the patients. Table 2 presents the score distributions for the physical functioning, emotional functioning, and global QL scales. At both assessments, these scores were very similar at the group level. Table 3 reports the correlations, means, standard deviations, and score ranges for the variables under study. As expected, the different indexes of change in physical functioning were significantly correlated (rs: .43 to .60). Change in physical functioning was weakly to moderately associated with change in emotional functioning (rs: .15 to .24) and change in global QL (rs: .26 to .38). Furthermore, the better off patients felt relative to others, the more positive the change in global QL (r .28). Importantly, social desirability was unrelated to changes in physical and emotional functioning, change in global QL, and relative evaluation. 3.2. Test of the Buffering model In the first test of the buffering model, we examined whether the association between change in physical condition and change in emotional functioning was moderated by the degree to which patients felt better off than others in a similar situation. When the ratings of patients or those of significant others of change in patients’ physical functioning were used, only main effects were statistically significant. However, using the rating of the research assistants, a significant two-way interaction was observed, Fch(1, 158)
4. Discussion In this article we have argued that persistence in downward evaluative comparison when faced with decline in physical health may be one of the mechanisms that bring about a response shift [10,12]. The better off patients whose physical condition has worsened feel compared to others in a similar situation, the stronger the indication of a response shift. Consistent with the buffering model of response shift
Table 3 Correlations, means, and standard deviations for the variables under study Variables
2
3
4
5
6
7
Mean
SD
Range
1. Physical P 2. Physical S 3. Physical R 4. Emotional functioning 5. Global QL 6. Relative evaluation 7. Social desirability
.43***
.60*** .45***
.24** .15* .28***
.33*** .38*** .26** .38***
.13 .04 .09 .12 .28***
.06 .09 .15
.00 .04 .08
2.4
1.3
2.9 1.3
1.9 5.37 1.63
21.9 23.3 15.6 18.1 20.3 1.28 1.64
60–40
80–80
50–50
50–58
92–67 2–7 0–5
Note: change. P patients’ ratings; S significant others’ ratings; R research assistants’ ratings. *p .05; **p .01; ***p .001
M. Hagedoorn et al. / Journal of Clinical Epidemiology 55 (2002) 176–183
Fig. 1. The association between change in patients, physical functioning (T2–T1: research assistants’ ratings) and change in emotional functioning (T2–T1) as a function of relative evaluation. Note: “The same off as others” reflects a relative evaluation score of 1 SD below the mean. “Better off than others” reflects a relative evaluation score of 1 SD above the mean.
[11], the findings support the mitigating effect of patients’ positive relative evaluation. More specifically, patients who considered themselves (much) better off than others appeared to be able to sustain their QL in the face of a worsening physical functioning, whereas those who felt the same or worse off as others could not. The current study restricted itself to an examination of self-reported emotional functioning and global QL. This was done for several reasons. Most importantly, a number of previous studies have reported rather high and stable levels of emotional functioning and QL among cancer patients; a finding that runs contrary to clinical expectations, and that is suggestive of a response shift phenomenon. Second, it has been suggested that response shift is more likely to occur when patients are asked to rate those aspects of their health and functioning that are more subjective and less concrete [1,37]. Conversely, the more specific and concrete the health concept being rated, the less likely a response shift will occur. Indeed, additional exploratory analyses revealed no interaction between changes in physical functioning and patients’ relative evaluation on very concrete and specific symptoms, including anorexia, nausea/vomiting, diarrhea, and constipation. In a similar vein, previous research has indicated that people are more likely to feel better off when comparing themselves to others on relatively abstract attributes such as empathy or intuition, rather than on more concrete issues such as number of friends [38]. Third, other functioning measures, such as social (i.e., interference of physical condition or medical treatment with family and social life) and role (i.e., limitations with respect to work or other daily activities) functioning, are closely linked to physical functioning, and therefore, not as appropriate for studying response shift. Although fatigue and pain depend on patients’ physical condition, these aspects also include a subjective component, which may be susceptible to response shift. However, additional exploratory analyses did not indicate an interaction effect between changes in physical functioning and patients’ relative evaluation on these two aspects of QL.
181
Fig. 2. The association between change in patients’ physical functioning (T2–T1: research assistants’ ratings) and change in global QL (T2–T1) as a function of relative evaluation. Note: “The same off as others” reflects a relative evaluation score of 1 SD below the mean. “Better off than others” reflects a relative evaluation score of 1 SD above the mean.
Support for the buffering effect of relative evaluation on self-reported global QL was consistent across all three indexes of change in physical functioning (based on patients’, significant others’, and research assistants’ ratings). For self-reported emotional functioning, evidence of the buffering effect of relative evaluation was found only when employing the change index for physical functioning based on the research assistants’ ratings. Although there is no clear explanation for this latter finding, it may be related in some way to differences in the way in which physical functioning was assessed by the various raters. The research staff did not complete the EORTC QLQ-C30, because it was not deemed feasible for them to respond to the detailed series of questions included in the questionnaire. It was possible for them to provide a more global rating of physical health using the ECOG performance status scale. Although the physical functioning subscale of the EORTC and the ECOG rating scales are similar, these scales are not identical in content, and thus are not strictly comparable. Although our results are consistent with theory, because we did not assess response shift directly, they do not provide unequivocal evidence that a positive relative evaluation results in a response shift in patients’ serial ratings of their emotional functioning and global QL. A frequently used technique for assessing response shift is to compare “then-test” scores (i.e., a renewed judgement of pretest level of QL at posttest) with pretest scores. Because the parent study was not directed at the issue of response shift, such then-test data were not available. However, a then-test also represents an indirect measure of response shift [39], and may be susceptible to recall bias. Sprangers and her colleagues [39] have recommended that different approaches to detecting response shift be compared. We would recommend that future studies be undertaken in which measures of social comparison behavior and the then-test technique are used as complementary approaches to assessing response shift in self-reported health status ratings. In our work we have assumed that patients’ relative evaluations represent the outcome of a social comparison pro-
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cess. It has been suggested that relative evaluations may simply reflect current health states, such as positive mood [40] or objectively defined physical functioning [41]. However, this is more likely to be of concern in cross-sectional studies, where direct links between patients’ positive relative evaluations and self-reported well-being are being investigated. Because the current study employed a longitudinal design, focused on changes in self-reported well-being, and tested a moderator model, this potential source of confounding may be less of a concern. Additionally, previous studies have reported positive correlations between frequency of downward comparison and positive evaluations of how well one is doing compared to others, suggesting that relative evaluations, at least in part, reflect social comparison processes [17,42]. Some of the patients in our sample declined to answer the relative evaluation question. Previous studies of individuals with serious health problems have reported a similar reluctance to make explicit social comparisons [19,43,44]. Such reticence might reflect a belief that such comparisons are socially undesirable, particularly when one rates oneself as being better off than others. However, we found no differences in scores on a measure of social desirability between those who did and did not complete the relative evaluation question. An alternative, and simpler explanation is that those individuals who did not provide a relative evaluation simply do not (or prefer not to) use this type of cognitive strategy [45]. In any case, completion of the relative evaluation item was unrelated to scores on the physical functioning, emotional functioning, and global QL measures. To our knowledge, this is the first longitudinal study investigating the buffering effect of a positive relative evaluation for cancer patients facing a decline in their physical health. Although our findings lend support to the buffering hypothesis, some caution needs to be introduced in generalizing our results to all patients with cancer. Approximately 15% of the eligible patients chose not to participate in the study, and approximately 25% of participating patients were lost to follow-up, primarily due to death or to the perceived physical or emotional burden of the study. In other words, the patients who faced the largest decline in health may not have been included in the study. Possibly, there is a limit to which the negative impact of declining physical health on QL can be counteracted by a positive relative evaluation. Additionally, the reversibility of the negative changes in physical health may be of importance. For example, it may be easier for patients to maintain a relatively high level of global QL when deteriorating physical health is due to the transient side effects of treatment. Future studies are needed to clarify these issues. The results of this study are not only of theoretical interest; they may have practical implications as well. Palliative cancer treatment is aimed at achieving tumor response and thus at lengthening survival. However, when objective improvement in health is no longer possible, cognitive and be-
havioral strategies may become increasingly important in mitigating the impact of disease progression on patients’ sense of well-being. As Wilson ([37], p. 1584) has stated: “When biological or physiological change is no longer possible (i.e., all ‘conventional’ therapies have been unsuccessfully tried), a principal goal of care might become the induction of scale recalibration, concept redefinition, or a change in values.” Consistent with the literature on response shift and on social comparison, the current results indicate that cognitive strategies that promote a patient’s sense of relative well-being are psychologically adaptive. This suggests that interventions aimed at facilitating the use of such cognitive techniques may be useful to patients and their families in learning to cope with the effects of cancer and its treatment on their daily lives.
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