- Email: [email protected]
Developing a measure of treatment beliefs: The complementary and alternative medicine beliefs inventory
Complementary Therapies in Medicine (2005) 13, 144—149
Developing a measure of treatment beliefs: The complementary and alternative medicine beliefs inventory夽 F.L. Bishop ∗, L. Yardley, G. Lewith Department of Psychology, University of Southampton, Highfield, Southampton SO17 1BJ, UK Summary Objectives: The study aimed to develop a comprehensive generic measure of treatment beliefs, the Complementary and Alternative Medicine Beliefs Inventory (CAMBI), and to identify distinct dimensions of CAM-related beliefs. Methods: The CAMBI and other measures were presented and advertised online. Results: 328 completed questionnaires were received. Factor analysis indicated three dimensions of beliefs could be identified. Subscales of the CAMBI were developed measuring beliefs in natural treatment, participation in treatment and holistic health. The subscales all had satisfactory reliability and were significantly correlated with CAM use (Spearman’s rho = .18, .47 and .22 for natural treatments, holistic health and participation in treatment, respectively). Conclusions: The CAMBI measures three distinct dimensions of treatment beliefs, all of which are related to CAM use. © 2005 Elsevier Ltd. All rights reserved.
Introduction Substantial proportions of people in the UK and other western nations use complementary and alternative medicine (CAM).1 To understand why peo夽 Funding: Felicity Bishop was supported by an ESRC CASE Studentship in collaboration with Boots plc. Dr. George Lewith’s post is funded by a grant from the Maurice Laing Foundation and at the time this research was carried out was a consultant to Boots plc. * Corresponding author. Tel.: +44 23 8059 2581; fax: +44 23 8059 4597. E-mail address: [email protected] (F.L. Bishop).
ple use CAM it is important to be able to measure the treatment beliefs of CAM users. Furthermore, it is necessary to measure a range of CAM-related beliefs in order to determine how different beliefs relate to specific aspects of CAM use; for example different beliefs might be related to the use of different types of CAM. This paper aims to extend our ability to measure CAM-related beliefs through the development of the CAM Beliefs Inventory (CAMBI). From a review of the existing literature it is possible to identify four distinct dimensions of beliefs associated with CAM use: beliefs in holistic health, holistic treatments, natural treatments and partici-
0965-2299/$ — see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ctim.2005.01.005
Developing a measure of treatment beliefs pation in treatment. Having holistic or post-modern value orientations involves believing that health and illness involve the whole person and was the most important attitudinal predictor of CAM use in a national US-based survey.2 In terms of holistic treatments, CAM users believe more strongly than conventional medicine users that the body has its own healing mechanisms.3 CAM users also hold strong beliefs in the importance of participating in treatment and being involved in decisionmaking, and value the control offered to patients in CAM.4,5 Believing that natural treatments are safer and more effective than orthodox medicines and valuing treatments with no side effects is also associated with CAM use.6,7 There are no well-developed existing questionnaires that measure all four of these aspects of relevant beliefs. Siahpush8 examined predictors of attitudes to CAM, including Natural Remedies, Holism and Rejection of Authority, constructs which overlap with those beliefs identified above as related to CAM use. However, published alpha coefficients for the scales indicate rather low reliability. The Holistic Complementary and Alternative Medicine Questionnaire (HCAMQ)9 is a welldeveloped questionnaire based on extensive pilot work with very good face validity and reliability. The HCAMQ measures beliefs in holistic health and the scientific validity of CAM but does not measure beliefs related to participation in treatment or natural treatments. The HCAMQ was therefore included in this study as a validating measure, to compare scores on the CAMBI with scores on a previously validated measure of CAM-related beliefs. The purpose of this study was to develop the CAMBI, a questionnaire capable of reliably measuring and distinguishing between beliefs in natural treatments, participation in treatment and holistic health and treatments. Our aim was to investigate whether four distinct dimensions would indeed emerge within our set of common CAM-related beliefs; confirm that reliable subscales could be constructed to measure the dimensions of beliefs identified in our data; and evaluate the validity of our scale, and its subscales, by examining the relationship of scale scores to CAM use and to scores on an existing well-validated measure of pro-CAM beliefs.
Method The CAMBI Existing research on CAM use was identified through computerised databases (Medline, PsychInfo, Web
145 of Knowledge), citation searching and hand searching of journals. A review of this literature was used to develop 57 items to measure beliefs in holistic health, holistic treatments, natural treatments, and participation in treatment. Five items with good face validity were taken from a previous study by Siahpush.8 The newly constructed items went through a selection process following which 15 were included in the CAMBI. The researchers assessed the relevance of the items to the proposed underlying dimensions of treatment beliefs (their content validity). Additional criteria included: commonly understood and non-technical terminology, neutral wording not involving leading questions or implicit value judgments, and simple grammatical construction. Five items were selected to measure beliefs in holistic health (items 12—15, 20), five for holistic treatments (items 4—6, 16, 17), five for natural treatments (items 1—3, 18, 19) and five for participation in treatment (items 7—11). Five items were worded to represent anti-CAM beliefs to guard against positive response biases by encouraging respondents to use both ends of the response scale (items 9, 11, 14, 17 and 19). (See Table 1 for CAMBI items.) A 7-point Likert-type response scale was used, ranging from 1 (labeled ‘strongly disagree’), through 4 (‘neither agree nor disagree’) to 7 (‘strongly agree’). Items displaying anti-CAM beliefs were reverse-scored. High scores on the CAMBI items indicate pro-CAM treatment beliefs.
The HCAMQ9 This 11-item questionnaire consists of two subscales (belief in the Scientific Validity of CAM and Holistic Health), and one overall composite scale. High scores on the HCAMQ indicate anti-CAM beliefs.
CAM use The total number of CAM forms ever used was a proxy measure for extent of CAM use. A 39-item checklist10 was used to measure the number of forms of CAM previously used by participants.
Presentation of questionnaires The questionnaires were presented on a website hosted by the University of Southampton and were available for 4 months. The internet offers an efficient medium through which to recruit a potentially large and diverse sample in a limited time period.11 Dreamweaver version 4 was used to construct the questionnaire website. Response scales were presented in a format as similar as possible to a paper
146
F.L. Bishop et al.
Table 1
Factor loadings of the CAMBI.
Item
Factor 1
1. 2. 3. 4. 5. 6.
Treatments should have no negative side effects It is important to me that treatments are non-toxic Treatments should only use natural ingredients It is important for treatments to boost my immune system Treatments should enable my body to heal itself Treatments should increase my natural ability to stay healthy
7. Treatment providers should treat patients as equal partners 8. Patients should take an active role in their treatment 9. Treatment providers should make all decisions about treatment (r) 10. Treatment providers should help patients make their own decisions about treatment 11. Treatment providers should control what is talked about during consultations (r) 12. 13. 14. 15. 16. 17. 18. 19. 20. a b
Health is about harmonizing your body, mind and spirita Imbalances in a person’s life are a major cause of illnessa Treatments should concentrate only on symptoms rather than the whole persona (r) Treatments should focus on people’s overall well-being I think my body has a natural ability to heal itselfa There is no need for treatments to be concerned with natural healing powers (r) I prefer natural remedies to medicineb Treatments should make use of modern scientific technology (r)b Health is about more than just keeping your body fita,b
2
3
.47 .40 .53 .61 .67 .61
.03 −.02 .09 −.12 −.14 −.25
.04 −.03 −.02 −.01 −.10 −.02
.10 .20 −.25 .06 −.14
−.52 −.64 −.61 −.50 −.38
.05 .09 −.25 −.02 −.20
.31 .38 −.20 .29 .24 .12 — — —
.01 .20 −.12 −.17 −.18 −.02 — — —
−.40 −.43 −.71 −.47 −.25 −.46 — — —
Item developed by Siahpush (1999); (r) indicates reverse scored items. Items 18, 19 and 20 were excluded prior to factor analysis.
version of the questionnaires. Radio buttons were used for Likert-type scales, check boxes for checklist items, and drop-down boxes for demographic items. Responses were coded and stored in a text file on the website. Data retrieval was protected by password access. Data was transferred into SPSS for Windows (version 10) for analysis.
Participants Three hundred and twenty-eight participants were recruited through advertisements and links placed on health-related websites and chat-rooms including www.wellbeing.com (a healthcare website, from which 56% of participants were recruited). The advertisements described the study as concerning peoples’ opinions about health, illness and treatment and their use of CAM. Eighty-five percent of participants were female and 44% were aged less than 30. Demographically the participants were thus broadly typical of CAM users.12 The majority of participants (61%) lived in the UK, 27% lived in the USA. The majority of participants (95%) reported having used at least one CAM form; the mean number of CAM forms used was 7.51 (S.D. = 5.47). The most popular CAM forms used by participants were aromatherapy
(used by 64% of participants), massage (63%), herbal medicine (56%), meditation (40%) and homeopathy (38%).
Statistical methods Factor analysis was used to examine the associations between responses to the questionnaire items and thus to determine the scale structure of the CAMBI. There was no a priori theoretical reason to expect the factors to be statistically independent and so oblique rotation was used (this technique permits factors to correlate with each other). Items with factor loadings higher than .32 were interpreted as belonging to that factor.13 Cronbach’s alpha statistics were calculated to determine the scales’ internal consistency (the extent to which items on each scale were answered in the same way; values of above .6 are satisfactory for scales with fewer than 10 items, which demonstrate good validity and make sense conceptually14 ). Correlations were conducted to confirm that responses to the CAMBI were related to CAM use (i.e. to determine the criterion validity of the questionnaire). It was expected that scores on all subscales of the CAMBI would be positively correlated with CAM use. Previous research has found medium sized correlations between attitudes to CAM and measures
Developing a measure of treatment beliefs
Table 2
147
Descriptive statistics for the CAMBI.
Scale
n
M
S.D.
Natural Treatments Participation in Treatment Holistic Health CAMBI
328 328 328 328
33.93 29.34 33.86 97.13
4.98 4.14 5.22 10.76
∗
Kolmogorov-Smirnov z
d.f.
.091* .124* .078* .034 (ns)
328 328 328 328
p < .001.
of behaviour, for example CAM use7 and use of vitamins9 (where .3 is considered a medium sized correlation15 ). Medium sized correlations were thus expected between scores on the CAMBI and CAM use. Correlations were also conducted between scores on the CAMBI and the HCAMQ to confirm that both questionnaires measure related beliefs (i.e. to demonstrate the congruent validity of the CAMBI). It was expected that scores on all subscales of the CAMBI would be negatively correlated with scores on the HCAMQ subscales. Siahpush found medium correlations between attitudes to CAM and beliefs related to CAM (such as beliefs in holism and natural remedies).8 Medium correlations were thus expected between the scales of the HCAMQ and CAMBI. Because the CAMBI contains items related to beliefs in participation in treatment and the HCAMQ does not contain such items, weaker correlations were expected between these subscales than between other subscales of these questionnaires (no specific hypotheses about the strength of such relationships were made). Bonferroni corrections were made for each set of correlations and alpha was set at .05 to protect against type I errors (i.e. spurious significant results as a consequence of conducting more than one significance test).
Results Factor analysis Preliminary factor analyses suggested that items 18, 19, and 20 did not emerge consistently with other items, contributing to unstable and difficult to interpret factor solutions. These items were excluded from the questionnaire. The scree test from an initial principal component analysis suggested a three-factor solution. Three factors were extracted using principal axis factoring with direct oblimin rotation. The factor loadings from the pattern matrix are shown in Table 1. The three factors were moderately correlated (Factors 1 and 2, r = −.16; Factors 1 and 3, r = −.31; Factors 2 and 3, r = .37). An over-
all scale including all items can thus be calculated, measuring belief in complementary and alternative approaches to health and illness. Factors were interpreted by examining the items with high loadings on each factor. Six items loaded highly on Factor 1, constituting a subscale measuring belief in Natural Treatments. Five items loaded highly on Factor 2, constituting a subscale measuring belief in Participation in Treatment. Five items loaded highly on Factor 3, and a sixth had a low loading of .25 (item 11). These items constitute a subscale measuring belief in Holistic Health.
Reliability Cronbach’s alpha values were satisfactory for all subscales. For Natural Treatments alpha = .75, for Participation in Treatment alpha = .68, for Holistic Health alpha = .73, and for the whole CAMBI alpha = .81. Subscales were constructed by summing scores on each item that loaded onto the appropriate factor. According to the Kolmogorov-Smirnov test the distribution of the subscales was significantly different from the normal distribution (Table 2). Therefore, non-parametric analyses were conducted.
Criterion validity Spearman’s correlation coefficients between the CAMBI and CAM use were all positive and significant;
Table 3 Intercorrelations between the CAMBI and CAM use. Scale 1. 2. 3. 4. 5.
1 2
3 *
4 *
5
CAMBI — .74 .82 .64 .39* Natural Treatments — .42* .29* .18* Holistic Health — .36* .47* Participation in Treatment — .22* CAM Use —
Note. Spearman’s correlation coefficients reported. ∗ p < .005.
*
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F.L. Bishop et al.
Table 4
Intercorrelations between the CAMBI and the HCAMQ.
Scale 1. 2. 3. 4. 5. 6. 7.
CAMBI Natural Treatmentsa Holistic Healtha Participation in Treatmenta HCAMQ HCAMQ Scientific Validity of CAM HCAMQ Holistic Health
1 —
2 .74 —
3 *
4 *
.82 .42* —
5 *
.64 .29* .36* —
6 *
−.55 −.38* −.53* −.28* —
7 *
−.44 −.30* −.46* −.19* .92* —
−.46* −.34* −.40* −.30* .59* .26* —
Note. Spearman’s correlation coefficients reported. a Subscales of the CAMBI. ∗ p < .0024.
higher scores on the CAMBI were associated with increased use of CAM (Table 3). In particular the Holistic Health subscale correlated well with CAM use (Spearman’s rho = .47). This pattern of correlations supports the criterion validity of the CAMBI.
Congruent validity Spearman’s correlation coefficients between the CAMBI and the HCAMQ were all negative and significant, demonstrating good congruent validity of the CAMBI (Table 4).
Discussion The CAMBI is a 17-item questionnaire with satisfactory validity and reliability measuring three aspects of CAM-related treatment beliefs. This study has shown that three distinct dimensions of CAMrelated treatment beliefs can be identified, beliefs in natural treatments, participation in treatment, and holistic health. As predicted, high scores on all three subscales were associated with use of a high number of CAM forms. The three-factor structure departed from the four aspects of treatment beliefs that the items were designed to measure. The hypothesised dimension of holistic treatments did not emerge as a distinct concept: items relating to a belief in natural healing abilities belonged to the holistic health scale while items relating to belief in the need for treatments to utilise natural healing resources belonged to the natural treatments scale. While not predicted, this pattern of subscales does have face validity and demonstrates that it is possible to distinguish between more than one underlying dimensions of CAM-related treatment beliefs. The highly pro-CAM sample of internet-users who participated in this study meant that it was not possible to make direct comparisons between the beliefs of CAM users and non-users. However, as our
aim was to distinguish between different treatment beliefs which are related to CAM use, it was appropriate to employ a pro-CAM sample which was demographically typical of CAM users. It is important to acknowledge however that there could be important differences between CAM users who are internet users and those who are not. Moreover, given the age profile of our sample it is likely that it included many relatively healthy CAM users. The applicability of the CAMBI to less healthy CAM users is thus unknown and further tests of the validity of the CAMBI in well-defined chronic illness groups are necessary to investigate the contexts within which the CAMBI can appropriately be employed. In comparison with existing questionnaires, the CAMBI is similar in content to the scales developed by Siahpush.8 Both questionnaires measure beliefs in holistic health and natural treatments and both include a scale relating to patients’ roles in treatment. However, the Holistic Health and Natural Treatments scales of the CAMBI demonstrated somewhat higher internal consistency than previously reported for the corresponding Siahpush subscales.8 As expected, the pattern of correlations between the CAMBI and the HCAMQ showed that beliefs in natural treatments and holistic health (from the CAMBI) are associated with beliefs in holistic health and attitudes to CAM (from the HCAMQ), while beliefs in participation in treatment are less strongly associated with the HCAMQ scales. These associations provide further support for the validity of the CAMBI while confirming that the CAMBI is a broader measure of treatment-related beliefs than the HCAMQ. Overall, the HCAMQ and the CAMBI have shown similar psychometric properties. Both questionnaires provide good measures of somewhat different treatment beliefs in the context of CAM use. In conclusion, the CAMBI measures and is able to distinguish between beliefs in natural treatments, participation in treatment, and holistic health.
Developing a measure of treatment beliefs
149
Acknowledgements The authors would like to thank Jin Zhang for her technical assistance and the Digital Wellbeing team at Boots plc for their assistance in advertising the study.
6. 7. 8.
References 1. Ernst E. Prevalence of use of complementary/alternative medicine: a systematic review. Bull World Health Organ 2000;78:252—7. 2. Astin JA. Why patients use alternative medicine. Results of a national study. J Am Med Asssoc 1998;279:1548— 53. 3. Furnham A, Smith C. Choosing alternative medicine: a comparison of the beliefs of patients visiting a general practitioner and a homeopath. Soc Sci Med 1988;26:685—9. 4. Downer SM, Cody MM, McCluskey P, Wilson PD, Lister TA, Slevin ML. Pursuit and practice of complementary therapies by cancer patients receiving conventional treatment. Br Med J 1994;309:86—9. 5. Balneaves LG, Kristjanson LJ, Tataryn D. Beyond convention: describing complementary therapy use by women
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10. 11. 12. 13. 14. 15.
living with breast cancer. Patient Educ Couns 1999; 38:143—53. Cassileth BR, Lusk EJ, Strouse TB, Bodenheimer BJ. Contemporary unorthodox treatments in cancer medicine. Ann Intern Med 1984;101:105—12. O’Callaghan FV, Jordan N. Postmodern values, attitudes and the use of complementary medicine. Complement Ther Med 2003;11:28—32. Siahpush M. Why do people favour alternative therapies? Aust NZ J Public Health 1999;23:266—71. Hyland ME, Lewith GT, Westoby C. Developing a measure of attitudes: the holistic complementary and alternative medicine questionnaire. Complement Ther Med 2003;11:33—8. Furnham A. How the public classify complementary medicine: a factor analytic study. Complement Ther Med 2000;8:82—7. Fyfe S, Leanard H, Gelmi R, Tassell A, Strack R. Using the internet to pilot a questionnaire on childhood disability in Rett syndrome. Child Care Health Dev 2001;27:535—43. Thomas KJ, Nicholl JP, Coleman P. Use and expenditure on complementary medicine in England: a population based survey. Complement Ther Med 2001;9:2—11. Tabachnick BG, Fidell LS. Using multivariate statistics. Boston: Allyn and Bacon; 2001. Loewenthal KM. An introduction to psychological tests and scales. Hove: Psychology Press Ltd.; 2001. Cohen J. A power primer. Psychol Bull 1992;112:155—9.
Developing a measure of treatment beliefs: The complementary and alternative medicine beliefs inventory夽 F.L. Bishop ∗, L. Yardley, G. Lewith Department of Psychology, University of Southampton, Highfield, Southampton SO17 1BJ, UK Summary Objectives: The study aimed to develop a comprehensive generic measure of treatment beliefs, the Complementary and Alternative Medicine Beliefs Inventory (CAMBI), and to identify distinct dimensions of CAM-related beliefs. Methods: The CAMBI and other measures were presented and advertised online. Results: 328 completed questionnaires were received. Factor analysis indicated three dimensions of beliefs could be identified. Subscales of the CAMBI were developed measuring beliefs in natural treatment, participation in treatment and holistic health. The subscales all had satisfactory reliability and were significantly correlated with CAM use (Spearman’s rho = .18, .47 and .22 for natural treatments, holistic health and participation in treatment, respectively). Conclusions: The CAMBI measures three distinct dimensions of treatment beliefs, all of which are related to CAM use. © 2005 Elsevier Ltd. All rights reserved.
Introduction Substantial proportions of people in the UK and other western nations use complementary and alternative medicine (CAM).1 To understand why peo夽 Funding: Felicity Bishop was supported by an ESRC CASE Studentship in collaboration with Boots plc. Dr. George Lewith’s post is funded by a grant from the Maurice Laing Foundation and at the time this research was carried out was a consultant to Boots plc. * Corresponding author. Tel.: +44 23 8059 2581; fax: +44 23 8059 4597. E-mail address: [email protected] (F.L. Bishop).
ple use CAM it is important to be able to measure the treatment beliefs of CAM users. Furthermore, it is necessary to measure a range of CAM-related beliefs in order to determine how different beliefs relate to specific aspects of CAM use; for example different beliefs might be related to the use of different types of CAM. This paper aims to extend our ability to measure CAM-related beliefs through the development of the CAM Beliefs Inventory (CAMBI). From a review of the existing literature it is possible to identify four distinct dimensions of beliefs associated with CAM use: beliefs in holistic health, holistic treatments, natural treatments and partici-
0965-2299/$ — see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ctim.2005.01.005
Developing a measure of treatment beliefs pation in treatment. Having holistic or post-modern value orientations involves believing that health and illness involve the whole person and was the most important attitudinal predictor of CAM use in a national US-based survey.2 In terms of holistic treatments, CAM users believe more strongly than conventional medicine users that the body has its own healing mechanisms.3 CAM users also hold strong beliefs in the importance of participating in treatment and being involved in decisionmaking, and value the control offered to patients in CAM.4,5 Believing that natural treatments are safer and more effective than orthodox medicines and valuing treatments with no side effects is also associated with CAM use.6,7 There are no well-developed existing questionnaires that measure all four of these aspects of relevant beliefs. Siahpush8 examined predictors of attitudes to CAM, including Natural Remedies, Holism and Rejection of Authority, constructs which overlap with those beliefs identified above as related to CAM use. However, published alpha coefficients for the scales indicate rather low reliability. The Holistic Complementary and Alternative Medicine Questionnaire (HCAMQ)9 is a welldeveloped questionnaire based on extensive pilot work with very good face validity and reliability. The HCAMQ measures beliefs in holistic health and the scientific validity of CAM but does not measure beliefs related to participation in treatment or natural treatments. The HCAMQ was therefore included in this study as a validating measure, to compare scores on the CAMBI with scores on a previously validated measure of CAM-related beliefs. The purpose of this study was to develop the CAMBI, a questionnaire capable of reliably measuring and distinguishing between beliefs in natural treatments, participation in treatment and holistic health and treatments. Our aim was to investigate whether four distinct dimensions would indeed emerge within our set of common CAM-related beliefs; confirm that reliable subscales could be constructed to measure the dimensions of beliefs identified in our data; and evaluate the validity of our scale, and its subscales, by examining the relationship of scale scores to CAM use and to scores on an existing well-validated measure of pro-CAM beliefs.
Method The CAMBI Existing research on CAM use was identified through computerised databases (Medline, PsychInfo, Web
145 of Knowledge), citation searching and hand searching of journals. A review of this literature was used to develop 57 items to measure beliefs in holistic health, holistic treatments, natural treatments, and participation in treatment. Five items with good face validity were taken from a previous study by Siahpush.8 The newly constructed items went through a selection process following which 15 were included in the CAMBI. The researchers assessed the relevance of the items to the proposed underlying dimensions of treatment beliefs (their content validity). Additional criteria included: commonly understood and non-technical terminology, neutral wording not involving leading questions or implicit value judgments, and simple grammatical construction. Five items were selected to measure beliefs in holistic health (items 12—15, 20), five for holistic treatments (items 4—6, 16, 17), five for natural treatments (items 1—3, 18, 19) and five for participation in treatment (items 7—11). Five items were worded to represent anti-CAM beliefs to guard against positive response biases by encouraging respondents to use both ends of the response scale (items 9, 11, 14, 17 and 19). (See Table 1 for CAMBI items.) A 7-point Likert-type response scale was used, ranging from 1 (labeled ‘strongly disagree’), through 4 (‘neither agree nor disagree’) to 7 (‘strongly agree’). Items displaying anti-CAM beliefs were reverse-scored. High scores on the CAMBI items indicate pro-CAM treatment beliefs.
The HCAMQ9 This 11-item questionnaire consists of two subscales (belief in the Scientific Validity of CAM and Holistic Health), and one overall composite scale. High scores on the HCAMQ indicate anti-CAM beliefs.
CAM use The total number of CAM forms ever used was a proxy measure for extent of CAM use. A 39-item checklist10 was used to measure the number of forms of CAM previously used by participants.
Presentation of questionnaires The questionnaires were presented on a website hosted by the University of Southampton and were available for 4 months. The internet offers an efficient medium through which to recruit a potentially large and diverse sample in a limited time period.11 Dreamweaver version 4 was used to construct the questionnaire website. Response scales were presented in a format as similar as possible to a paper
146
F.L. Bishop et al.
Table 1
Factor loadings of the CAMBI.
Item
Factor 1
1. 2. 3. 4. 5. 6.
Treatments should have no negative side effects It is important to me that treatments are non-toxic Treatments should only use natural ingredients It is important for treatments to boost my immune system Treatments should enable my body to heal itself Treatments should increase my natural ability to stay healthy
7. Treatment providers should treat patients as equal partners 8. Patients should take an active role in their treatment 9. Treatment providers should make all decisions about treatment (r) 10. Treatment providers should help patients make their own decisions about treatment 11. Treatment providers should control what is talked about during consultations (r) 12. 13. 14. 15. 16. 17. 18. 19. 20. a b
Health is about harmonizing your body, mind and spirita Imbalances in a person’s life are a major cause of illnessa Treatments should concentrate only on symptoms rather than the whole persona (r) Treatments should focus on people’s overall well-being I think my body has a natural ability to heal itselfa There is no need for treatments to be concerned with natural healing powers (r) I prefer natural remedies to medicineb Treatments should make use of modern scientific technology (r)b Health is about more than just keeping your body fita,b
2
3
.47 .40 .53 .61 .67 .61
.03 −.02 .09 −.12 −.14 −.25
.04 −.03 −.02 −.01 −.10 −.02
.10 .20 −.25 .06 −.14
−.52 −.64 −.61 −.50 −.38
.05 .09 −.25 −.02 −.20
.31 .38 −.20 .29 .24 .12 — — —
.01 .20 −.12 −.17 −.18 −.02 — — —
−.40 −.43 −.71 −.47 −.25 −.46 — — —
Item developed by Siahpush (1999); (r) indicates reverse scored items. Items 18, 19 and 20 were excluded prior to factor analysis.
version of the questionnaires. Radio buttons were used for Likert-type scales, check boxes for checklist items, and drop-down boxes for demographic items. Responses were coded and stored in a text file on the website. Data retrieval was protected by password access. Data was transferred into SPSS for Windows (version 10) for analysis.
Participants Three hundred and twenty-eight participants were recruited through advertisements and links placed on health-related websites and chat-rooms including www.wellbeing.com (a healthcare website, from which 56% of participants were recruited). The advertisements described the study as concerning peoples’ opinions about health, illness and treatment and their use of CAM. Eighty-five percent of participants were female and 44% were aged less than 30. Demographically the participants were thus broadly typical of CAM users.12 The majority of participants (61%) lived in the UK, 27% lived in the USA. The majority of participants (95%) reported having used at least one CAM form; the mean number of CAM forms used was 7.51 (S.D. = 5.47). The most popular CAM forms used by participants were aromatherapy
(used by 64% of participants), massage (63%), herbal medicine (56%), meditation (40%) and homeopathy (38%).
Statistical methods Factor analysis was used to examine the associations between responses to the questionnaire items and thus to determine the scale structure of the CAMBI. There was no a priori theoretical reason to expect the factors to be statistically independent and so oblique rotation was used (this technique permits factors to correlate with each other). Items with factor loadings higher than .32 were interpreted as belonging to that factor.13 Cronbach’s alpha statistics were calculated to determine the scales’ internal consistency (the extent to which items on each scale were answered in the same way; values of above .6 are satisfactory for scales with fewer than 10 items, which demonstrate good validity and make sense conceptually14 ). Correlations were conducted to confirm that responses to the CAMBI were related to CAM use (i.e. to determine the criterion validity of the questionnaire). It was expected that scores on all subscales of the CAMBI would be positively correlated with CAM use. Previous research has found medium sized correlations between attitudes to CAM and measures
Developing a measure of treatment beliefs
Table 2
147
Descriptive statistics for the CAMBI.
Scale
n
M
S.D.
Natural Treatments Participation in Treatment Holistic Health CAMBI
328 328 328 328
33.93 29.34 33.86 97.13
4.98 4.14 5.22 10.76
∗
Kolmogorov-Smirnov z
d.f.
.091* .124* .078* .034 (ns)
328 328 328 328
p < .001.
of behaviour, for example CAM use7 and use of vitamins9 (where .3 is considered a medium sized correlation15 ). Medium sized correlations were thus expected between scores on the CAMBI and CAM use. Correlations were also conducted between scores on the CAMBI and the HCAMQ to confirm that both questionnaires measure related beliefs (i.e. to demonstrate the congruent validity of the CAMBI). It was expected that scores on all subscales of the CAMBI would be negatively correlated with scores on the HCAMQ subscales. Siahpush found medium correlations between attitudes to CAM and beliefs related to CAM (such as beliefs in holism and natural remedies).8 Medium correlations were thus expected between the scales of the HCAMQ and CAMBI. Because the CAMBI contains items related to beliefs in participation in treatment and the HCAMQ does not contain such items, weaker correlations were expected between these subscales than between other subscales of these questionnaires (no specific hypotheses about the strength of such relationships were made). Bonferroni corrections were made for each set of correlations and alpha was set at .05 to protect against type I errors (i.e. spurious significant results as a consequence of conducting more than one significance test).
Results Factor analysis Preliminary factor analyses suggested that items 18, 19, and 20 did not emerge consistently with other items, contributing to unstable and difficult to interpret factor solutions. These items were excluded from the questionnaire. The scree test from an initial principal component analysis suggested a three-factor solution. Three factors were extracted using principal axis factoring with direct oblimin rotation. The factor loadings from the pattern matrix are shown in Table 1. The three factors were moderately correlated (Factors 1 and 2, r = −.16; Factors 1 and 3, r = −.31; Factors 2 and 3, r = .37). An over-
all scale including all items can thus be calculated, measuring belief in complementary and alternative approaches to health and illness. Factors were interpreted by examining the items with high loadings on each factor. Six items loaded highly on Factor 1, constituting a subscale measuring belief in Natural Treatments. Five items loaded highly on Factor 2, constituting a subscale measuring belief in Participation in Treatment. Five items loaded highly on Factor 3, and a sixth had a low loading of .25 (item 11). These items constitute a subscale measuring belief in Holistic Health.
Reliability Cronbach’s alpha values were satisfactory for all subscales. For Natural Treatments alpha = .75, for Participation in Treatment alpha = .68, for Holistic Health alpha = .73, and for the whole CAMBI alpha = .81. Subscales were constructed by summing scores on each item that loaded onto the appropriate factor. According to the Kolmogorov-Smirnov test the distribution of the subscales was significantly different from the normal distribution (Table 2). Therefore, non-parametric analyses were conducted.
Criterion validity Spearman’s correlation coefficients between the CAMBI and CAM use were all positive and significant;
Table 3 Intercorrelations between the CAMBI and CAM use. Scale 1. 2. 3. 4. 5.
1 2
3 *
4 *
5
CAMBI — .74 .82 .64 .39* Natural Treatments — .42* .29* .18* Holistic Health — .36* .47* Participation in Treatment — .22* CAM Use —
Note. Spearman’s correlation coefficients reported. ∗ p < .005.
*
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F.L. Bishop et al.
Table 4
Intercorrelations between the CAMBI and the HCAMQ.
Scale 1. 2. 3. 4. 5. 6. 7.
CAMBI Natural Treatmentsa Holistic Healtha Participation in Treatmenta HCAMQ HCAMQ Scientific Validity of CAM HCAMQ Holistic Health
1 —
2 .74 —
3 *
4 *
.82 .42* —
5 *
.64 .29* .36* —
6 *
−.55 −.38* −.53* −.28* —
7 *
−.44 −.30* −.46* −.19* .92* —
−.46* −.34* −.40* −.30* .59* .26* —
Note. Spearman’s correlation coefficients reported. a Subscales of the CAMBI. ∗ p < .0024.
higher scores on the CAMBI were associated with increased use of CAM (Table 3). In particular the Holistic Health subscale correlated well with CAM use (Spearman’s rho = .47). This pattern of correlations supports the criterion validity of the CAMBI.
Congruent validity Spearman’s correlation coefficients between the CAMBI and the HCAMQ were all negative and significant, demonstrating good congruent validity of the CAMBI (Table 4).
Discussion The CAMBI is a 17-item questionnaire with satisfactory validity and reliability measuring three aspects of CAM-related treatment beliefs. This study has shown that three distinct dimensions of CAMrelated treatment beliefs can be identified, beliefs in natural treatments, participation in treatment, and holistic health. As predicted, high scores on all three subscales were associated with use of a high number of CAM forms. The three-factor structure departed from the four aspects of treatment beliefs that the items were designed to measure. The hypothesised dimension of holistic treatments did not emerge as a distinct concept: items relating to a belief in natural healing abilities belonged to the holistic health scale while items relating to belief in the need for treatments to utilise natural healing resources belonged to the natural treatments scale. While not predicted, this pattern of subscales does have face validity and demonstrates that it is possible to distinguish between more than one underlying dimensions of CAM-related treatment beliefs. The highly pro-CAM sample of internet-users who participated in this study meant that it was not possible to make direct comparisons between the beliefs of CAM users and non-users. However, as our
aim was to distinguish between different treatment beliefs which are related to CAM use, it was appropriate to employ a pro-CAM sample which was demographically typical of CAM users. It is important to acknowledge however that there could be important differences between CAM users who are internet users and those who are not. Moreover, given the age profile of our sample it is likely that it included many relatively healthy CAM users. The applicability of the CAMBI to less healthy CAM users is thus unknown and further tests of the validity of the CAMBI in well-defined chronic illness groups are necessary to investigate the contexts within which the CAMBI can appropriately be employed. In comparison with existing questionnaires, the CAMBI is similar in content to the scales developed by Siahpush.8 Both questionnaires measure beliefs in holistic health and natural treatments and both include a scale relating to patients’ roles in treatment. However, the Holistic Health and Natural Treatments scales of the CAMBI demonstrated somewhat higher internal consistency than previously reported for the corresponding Siahpush subscales.8 As expected, the pattern of correlations between the CAMBI and the HCAMQ showed that beliefs in natural treatments and holistic health (from the CAMBI) are associated with beliefs in holistic health and attitudes to CAM (from the HCAMQ), while beliefs in participation in treatment are less strongly associated with the HCAMQ scales. These associations provide further support for the validity of the CAMBI while confirming that the CAMBI is a broader measure of treatment-related beliefs than the HCAMQ. Overall, the HCAMQ and the CAMBI have shown similar psychometric properties. Both questionnaires provide good measures of somewhat different treatment beliefs in the context of CAM use. In conclusion, the CAMBI measures and is able to distinguish between beliefs in natural treatments, participation in treatment, and holistic health.
Developing a measure of treatment beliefs
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Acknowledgements The authors would like to thank Jin Zhang for her technical assistance and the Digital Wellbeing team at Boots plc for their assistance in advertising the study.
6. 7. 8.
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