Annals of Oncology Advance Access originally published online on October 26, 2007
Annals of Oncology 2008 19(1):49-55; doi:10.1093/annonc/mdm494
quality of life |
Psychological and behavioral mechanisms influencing the use of complementary and alternative medicine (CAM) in cancer patients
1 Department of Psychology and Behavioral Sciences, Graduate School of Human Sciences, Center for the Study of Communication Design, and Department of Complementary and Alternative Medicine, Graduate School of Medicine
2 Graduate School of Human Sciences, Osaka University, Osaka
3 Department of Psychosomatic Medicine, National Hospital Organization, Kinki-chuo Chest Medical Center, Osaka
4 Department of Palliative Care, Hikone Hospital, Hikone
5 Department of Psycho-Oncology, National Kyushu Cancer Center, Kyushu
6 Department of Complementary and Alternative Medicine, Graduate School of Medicine, Osaka University, Osaka
7 Department of Urology, Shikoku Cancer Center, Matsuyama
8 Division of Gastroenterology, University of Tsukuba, Tsukuba, Ibaraki, Japan
* Correspondence to: Dr K. Hirai, Graduate School of Human Sciences, Osaka University, 1-2 Yamadaoka, Suita Osaka 565-0871, Japan. Tel: +81-6-6879-8060; Fax: +81-6-6879-8060; E-mail: khirai{at}grappo.jp
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Abstract |
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Background: This study explored the psychological and behavioral mechanisms of complementary and alternative medicine (CAM) use in Japanese cancer patients using two applied behavioral models, the transtheoretical model (TTM), and theory of planned behavior (TPB).
Patients and methods: Questionnaires were distributed to 1100 patients at three cancer treatment facilities in Japan and data on 521 cancer patients were used in the final analysis. The questionnaire included items based on TTM and TPB variables, as well as three psychological batteries.
Results: According to the TTM, 88 patients (17%) were in precontemplation, 226 (43%) in contemplation, 33 (6%) in preparation, 71 (14%) in action, and 103 (20%) in maintenance. The model derived from structural equation modeling revealed that the stage of CAM use was significantly affected by the pros, cons, expectation from family, norms of medical staff, use of chemotherapy, period from diagnosis, and place of treatment. The primary factor for the stage of CAM use was the expectation from family.
Conclusions: The findings revealed the existence of a number of psychologically induced potential CAM users, and psychological variables including positive attitude for CAM use and perceived family expectation greatly influence CAM use in cancer patients.
Key words: CAM, cancer patients, psychological adjustment, theory of planned behavior, transtheoretical model
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introduction |
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TopAbstractintroductionpatients and methodsresultsdiscussionfundingAcknowledgementsReferences |
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Cancer patients use nutritional supplements, psychological techniques, and natural medical approaches together with conventional medicine, or in replace of conventional therapy, which are so-called complementary and alternative medicine (CAM). Recent surveys have demonstrated the high prevalence of CAM use by cancer patients. Sixty-seven percent of Canadian respondents reported using CAM, most often in an attempt to boost the immune system [1]. The first national survey on the use of CAM in Japan revealed that 45% of Japanese cancer patients have used CAM [2].
CAM is defined by the National Center for Complementary and Alternative Medicine as ‘a group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine’ [3] In addition, a new operational definition of CAM was proposed that it should include patients’ perspectives, such as individual goals, objectives, and beliefs of the patients [4]. Therefore, it is important to consider psychological aspects such as patients’ background, reasons or intentions for using CAM in oncology.
Several studies have explored the background and reasoning behind CAM use [1, 5–7]. CAM use in early-stage breast cancer patients was regarded as a marker of greater psychosocial distress and a worse quality of life [7] and advanced-stage cancer patients who used CAM had higher levels of anxiety and pain, lower satisfaction with conventional medicine, and a lower need for control over treatment decisions [8]. Alternatively, the use of CAM by cancer patients has not been associated with perceived distress or poor compliance with medical treatment [9]. However, the psychological and behavioral mechanisms of CAM use have not yet been clarified. Therefore, we carried out a multicenter cross-sectional survey to explore the psychological mechanism of CAM use in Japanese cancer patients from patients’ perspectives, using the transtheoretical model (TTM), and the theory of planned behavior (TPB).
The TTM [10] is useful for explaining changes in health behavior and has been used in various programs such as smoking cessation [11], genetic testing for colorectal cancer [12], and mammography adoption [13]. In the TTM, the decisional balance between pros and cons—positive and negative attitudes for the behavior—will account for the state of change observed during five stages: precontemplation, contemplation, preparation, action, and maintenance [10]. We adopted this classification to explain the behavioral intention of patients using CAM in cancer treatment. Moreover, self-efficacy, which acts as a mediating function for the psychological adjustment of cancer patients [14, 15], is an important factor affecting a person's movement from one stage to another.
The TPB [16] examines behavioral intentions based on three major components: the patient's attitude towards the behavior, perceived control, and subjective norms. In cases of cancer patients, attitude towards behavior may include perceived effectiveness of treatment, anxiety regarding side-effects, etc. Perceived control is the individual's perception of the extent to which performance of the behavior is easy or difficult, and is synonymous with the concept of self-efficacy [16]. Subjective norms in cancer CAM include expectation from family members, and norms of medical staff towards the patients.
Our hypotheses are as follows: (i) cancer patients are classified into five stages of CAM use, (ii) the stage of CAM use is explained by TTM and TPB variables, and (iii) perceived control positively correlates with CAM use and mediates between CAM use and psychological adjustment.
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participants
This study was approved by the institutional review boards of the Kinki Chuo Chest Disease Center, National Kyushu Cancer Center, and National Shikoku Cancer Center. From April 2005 to August 2005, a total of 1100 questionnaires were distributed to patients at each institute. Patients were enrolled in the study after their attending physician assessed if they met the following conditions: were receiving medical treatment through the outpatient or inpatient units at any of the three cancer centers, had an Eastern Cooperative Oncology Group performance status [17] from zero to three, were physically able to fill in the questionnaires by themselves, and had no cognitive impairment. On the questionnaire, we explained the purpose of the study and the fact that returning the questionnaire would be regarded as consent for participation; though we asked the patients to return the questionnaires anonymously.
measures
For this study, we developed our own questionnaire to examine CAM use in cancer patients (available from the authors). The questionnaire contained 85 items and it took about 20 min to complete. On the cover page of the questionnaire, CAM was defined using same definition of our previous survey [2]: ‘as any therapy is not included in the orthodox biomedical framework of care for patients, which includes remedies used without the approval of the relevant government authorities of new drugs after peer review of preclinical experiments and clinical trials regulated by law. Health insurance does not usually cover the cost of CAM, and patients are generally liable for all expenses incurred by CAM use. CAM may include use of natural products from mushrooms, herbs, green tea, shark cartilage, megavitamins, or other special foods, and may incorporate acupuncture, aromatherapy, massage, meditation, etc’. Additionally, a sheet containing 20 examples of CAM therapies and products was attached to the questionnaire. The first portion of the questionnaire asked for information on the patients’ background, including type of disease, age at onset, current age, gender, educational level, economic status, type of cancer treatment, satisfaction with treatment, smoking, drinking, and social support measured by the single item Tangible Social Support Scale [18].
The second part of the questionnaire included items originally designed to evaluate the cancer CAM-specific TTM and TPB variables. To measure the patients’ subjective intention with regard to CAM use, we additionally defined cancer CAM use as those ‘using any supplements or dietary foods or receiving any therapy that appears to have anticancer effects or auxiliary effect to that of conventional cancer therapy'. Respondents were asked to rate themselves based on the five stages of the TTM [10]: precontemplation ("I have no interest in using CAM"), contemplation ("I have been thinking that I might want to use CAM"), preparation ("I am preparing to use CAM"), action ("I have already used CAM in the last 6 months"), and maintenance ("I have already used CAM for >6 months"). The next section was composed of 27 items measuring TTM and TPB variables. The items were measured on a five-point Likert-type scale that ranged from ‘not at all’ (1) to ‘extremely’ (5). They included following five categories, (i) positive attitudes for CAM; (ii) pros; (iii) cons; (iv) expectation from family; and (v) norms of medical staff. The items were developed in our previous study on CAM [2] and another study on dietary food intake [19]. We used 16 from 27 items using confirmatory factor analysis on the current data as structurally valid and reliable items (Table 1). Also, content validity of the all TTM and TPB items in this part was confirmed by experts of two physicians, one psychiatrist and two psychologists.
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To assess psychological adjustment, we used the Japanese version [20] of the Hospital Anxiety and Depression Scale (HADS) [21], which has 14 questions on anxiety and depression with each question rated from 0 to 3. The validity and reliability of the Japanese HADS in cancer patients has been confirmed previously [22].
To assess perceived control in patients, we used the Self-Efficacy for Advanced Cancer (SEAC) scale, which was designed to evaluate self-efficacy of cancer patients [23]. The SEAC scale has 18 items with three subscales: symptom coping efficacy, activities of daily living efficacy (ADE), and affect regulation efficacy (ARE). The scale was formatted on an 11-point Likert-type scale ranging from 0 (not at all confident) to 100 (totally confident). The reliability and validity of this scale were also confirmed [23].
Finally, the Japanese version of the MD Anderson Symptom Inventory (MDASI-J) [24] was developed as a brief multiple-symptom assessment scale. It consisted of 13 symptom items [25], and its validity and reliability were confirmed [24]. We used 10 of the 13 physical symptom items for our statistical analyses since the items for distress, sadness, and remembrance were significantly and highly correlated with the HADS total score (r = 0.0479, P < 0.001; r = 0.456, P < 0.001; r = 0.334, P < 0.001, respectively).
statistical analyses
Descriptive analyses were carried out summarizing the participants’ backgrounds and scores following psychological measurements. Those with >30% missing values on the questionnaire were excluded from the analyses. The factors predicting stage of CAM use were analyzed through univariate analysis using the analysis of variance. In order to carry out multivariate analyses, we transformed the participants’ responses for the stage of CAM use into a numeric scale ranging from 1 to 5 points (1, precontemplation; 2, contemplation; 3, preparation; 4, action; and 5, maintenance), according to a previous study [15]. Next, structural equation modeling (SEM) using the maximum likelihood method was carried out to test the model. Because the model needed a parsimonious structure, we used the mean scores of SEAC as ‘self-efficacy', the total score of HADS as ‘psychological distress', and the mean scores of 10 items of MDASI-J as ‘physical sympotom'. We conducted all statistical analyses using SPSS (version 14.0) and AMOS (version 5.0.1) software packages.
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results |
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response rate to questionnaire
Of the 1100 questionnaires, 750 were given to inpatients and 350 to outpatients. Out of the 651 questionnaires returned (response rate 59.2%), 521 were valid for statistical analyses. The rest (n = 130) were invalid because of the lack of major information such as disease name or stage of CAM use. Moreover, questionnaires from noncancer patients were excluded from the analyses. Thus, the rate of valid replies was 47.4%.
backgrounds of patients and distribution of CAM use
The participants consisted of 246 males and 270 females, and five unknowns. Table 2 summarizes the demographic and diagnostic information of the participants. For staging, 88 patients (16.9%) were in precontemplation, 226 (43.4%) in contemplation, and 31 (6.6%) in preparation among the 347 CAM nonusers (66.6%), with 71 (13.6%) in action and 103 (19.8%) in maintenance among the 174 CAM users (33.4%). Table 1 also shows the prevalence of the five stages of CAM use categorized by demographic and medical status variables. The prevalence of CAM use in the higher stages, including action and maintenance, was significantly higher in patients who received chemotherapy (P < 0.001), those dissatisfied with current conventional treatment (P < 0.05), and outpatients (P < 0.001).
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psychosocial factors associated with the stages of CAM use
Table 3 shows the mean response and the results of the univariate analyses for psychological variables, physical symptom variables, and social support obtained from patients at each of the five stages of CAM use. There were significant differences amongst patients in the five stages based on pros (P < 0.001), cons (P < 0.001), positive attitude for CAM (P < 0.001), and expectation from family members (P < 0.001). There was a slightly higher response on ADE (P < 0.10) in patients who were in the action and maintenance stages.
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structural model for stages of CAM use
We carried out SEM by first selecting 14 variables in the initial model because they were observed to be significant predictors in the univariate analysis or were essential components for the TTM and TPB theories: use of chemotherapy, period from diagnosis, whether need for treatment was met, treatment place, stage of CAM use, psychological distress, pros, cons, positive attitude, expectation from family members, norms of medical staff, self-efficacy, psychological distress, physical symptoms, and social support. Next, we drew all paths according to the results of the correlation analysis. Since there was a significantly strong correlation between the pros and a positive attitude (r = 0.80, P < 0.001), and since the explanation by the TTM is given a priority for our purposes, we dropped positive attitude from the initial model. We repeated the SEM and sequentially dropped paths that were not significant until all the paths in the model became significant (P < 0.05). The variable ‘met need for treatment’ was dropped from the model because all the paths from this variable became not significant.
Figure 1 represents the final model. The fit indices for this model were excellent and included the following: chi-square (39) = 71.8, P = 0.001; Goodness of fit index = 0.98; Adjusted goodness of fit index = 0.96; Comparative Fit Index = 0.97; and Root Mean Square Error of Approximation = 0.04. Overall, the final model accounted for 41% of the variance in the stage of CAM use and 28% of the variance in psychological distress. The parameter with the highest value that explained the stage of CAM use was expectation from family members (beta = 0.37, P < 0.001). Furthermore, norms of medical staff and pros and cons all had significant direct effects on the stage of CAM use (beta = –0.12, P < 0.01; beta = 0.21, P < 0.001; and beta = –0.17, P < 0.001, respectively). The demographic and medical status variables that significantly explained the stage of CAM use included receiving chemotherapy (beta = 0.09, P < 0.01), period from diagnosis (beta = 0.37, P < 0.001), and treatment place (beta = –0.10, P < 0.01). The parameter with the highest value that explained psychological distress was self-efficacy (beta = 0.17, P < 0.001). Moreover, social support significantly affected psychological distress (beta = –0.14, P < 0.001). Finally, the stage of CAM use significantly, though only partially, affected psychological distress (beta = 0.10, P < 0.01).
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discussion |
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TopAbstractintroductionpatients and methodsresultsdiscussionfundingAcknowledgementsReferences |
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Our survey revealed that 33% of the participants used CAM as a replacement or an adjuvant to conventional cancer treatment. The rate of CAM use in this study approximately corresponded to the rate in a previous study [26], but was lower than the rate observed in a Japanese national survey [2]. This is likely due to the fact that our sample consisted of a much smaller number of patients from the palliative care unit (n = 24, 4.7%) compared with the previous study (n = 289, 9.3%). When we grouped participants into the five TTM stages of CAM use, the contemplation stage had the largest population (N = 226, 43.4%). Although these participants did not use CAM, they expressed interest in using it in the near future. Therefore, we concluded that a majority of our participants were potential CAM users.
Using SEM, we determined that 41% of the variance in advance of the CAM use stage was mainly due to the following TTM and TPB variables: expectation from family (positive), pros (positive), norms of medical staff (negative), and cons (negative). Three demographic and medical status variables were statistically significant in explaining CAM use, but their size was smaller than the other psychological variables. Therefore, we concluded that psychological variables are important factors promoting CAM use. With psychological variables, the pattern in which pros were positive predictors and cons were negative predictors of a person’s stage, is consistent with the theoretical postulation of the TTM [10]. The most frequent pro notion regarding CAM was that it ‘boosts physical and immune strength’, while the most frequent con was that it had ‘unpleasant side-effects’ [‘agree’ and ‘strongly agree’ response: N = 272 (53%); N = 187 (38%), respectively]. Thus, beliefs regarding the positive outcome of CAM were strong motivations for CAM use, but patients simultaneously worried about the adverse effects. Therefore, if the patients’ perceived balance between the pros and cons of CAM was to be changed by acquiring new information on CAM—e.g. the positive effect of a certain CAM product was empirically proven by a clinical trial—many patients in the contemplation stage would likely then use CAM. Therefore, it is important to provide evidence based and easy to understand information on CAM use in a systematic way, such as guidebooks or web resources, and to develop clinical guidelines on CAM use.
Another unique feature of CAM use that we determined is that the expectation from family in TPB explained the largest part of the variance in the CAM use stage. Previous studies have reported that family and friends of cancer patients generally provided information, supported the decision, or recommended the use of CAM [2, 27, 28], and that CAM users were not autonomous problem solvers [29]. Therefore, our result makes much clear of the critical role that patient recognition of family pressure plays during the decision-making process for CAM use.
Previous studies have indicated that the use of CAM was a marker of bad psychological adjustment [6] and had positive effects on patients’ sense of control [30]. On our results, progressed stage of CAM use significantly but not strongly predicted psychological distress, which was mainly explained by self-efficacy, that is, perceived control, and it did not directly explain CAM use stage and mediated by cons. In summary, CAM use did not directly provide perceived control to patients but a little worse psychological adjustment. We could not obtain the evidence that perceived control had strongly mediated the relationship between CAM use and psychological adjustment.
The limitations to this study include the cross-sectional design and sample. Use of SEM could have made clear of multiple relationships among variables in the cross-sectional design. This study also used a convenient sample recruited from three cancer centers. In order to obtain epidemiological details of the CAM use, we need to carry out a large sample prospective study confirming the results of this study. The response rate of our study, 59% was slightly higher than that of our previous national survey, 57% [2]. However, the valid response rate was 47%, mainly due to the missing of a single item for stage of CAM use. These indicated that sampling was valid, however it will limit generality of our results. It might be needed to improve assessment for stage of CAM use in the questionnaire.
In conclusion, this study using two psychological model provided strong evidence that the existence of psychologically induced potential CAM users and psychological variables including positive attitude for CAM use and perceived family expectation greatly influence CAM use in cancer patients.
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Japanese Ministry of Health, Labor and Welfare (13-20 and 17-14).
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Acknowledgements |
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We thank Hirokazu Arai, Mariko Shiozaki, Nanako Nakamura, Satoshi Ohno, Noriko Amano, Yutaka Kano, and James Prochaska for their generous assistance in the conduct of our research and their helpful comments on this paper.
Received for publication May 8, 2007. Revision received September 6, 2007. Accepted for publication September 14, 2007.
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