Introduction
In recent years, there has been growing interest for mindfulness in the treatment of chronic pain and psychological distress. Mindfulness refers to a state of being attentive to and aware of experiences (including physical sensations, emotions, thoughts, imagery) occurring in the present moment in a nonjudgmental or accepting way [
1,
2]. It can be contrasted with a state of being caught up by memories, plans, fantasies or worries, and behaving on ‘automatic pilot’, without paying attention to one’s actions [
1]. Mindfulness, which is usually taught by a variety of meditation and/or attention exercises and psychoeducation, has been incorporated into several treatment programs. Well-known programs include mindfulness-based stress reduction [
3], mindfulness-based cognitive therapy [
4], dialectical behaviour therapy [
5,
6], acceptance and commitment therapy [
7] and acceptance-based behavioural therapy [
8]. The effectiveness of these programs in reducing medical and psychological symptoms and improving quality of life has been shown in a wide range of clinical and nonclinical populations including patients with rheumatic conditions [
8‐
14].
To get insight into the mechanisms that produce these beneficial effects, for example the mediating effects of different mindfulness facets, proper assessment of mindfulness is necessary. Several self-report measures of mindfulness have been developed, including the Freiburg Mindfulness Inventory [
15], the Kentucky Inventory of Mindfulness Skills [
16], the Mindful Attention Awareness Scale [
1], the Cognitive and Affective Mindfulness Scale [
17] and the Southampton Mindfulness Questionnaire [
18]. Although these measures have shown satisfactory psychometric qualities [
2], they differ in generalizability, content and structure, suggesting the lack of consensus among researchers about the operationalization of the construct mindfulness. Recently, Baer et al. have performed a study on the facet structure of mindfulness [
2]. They combined the items of existing mindfulness questionnaires and conducted an exploratory factor analysis on all items. This analysis revealed five facets of mindfulness: (1) observing, defined in terms of noticing or attending to internal and external experiences; (2) describing, defined in terms of labelling internal experiences with words; (3) acting with awareness, defined in terms of attending to one’s activities of the moment (opposite of acting on automatic pilot); (4) nonjudging of inner experience, defined in terms of taking a nonevaluative stance toward thoughts and feelings; and (5) nonreactivity to inner experience, defined in terms of allowing thoughts and feelings to come and go, without getting caught up in or carried away by them. The items with the highest loadings on these facets were selected and combined, resulting in a new mindfulness questionnaire: the Five Facet Mindfulness Questionnaire (FFMQ). The FFMQ has been tested in meditating and in student samples and has shown good psychometric properties [
2,
19]. The FFMQ, however, has never been validated in a clinical sample, which is important given the wide implementation of mindfulness interventions in clinical populations. Moreover, test–retest reliability has never been investigated.
This study focused on the psychometric properties of the FFMQ in a clinical population of fibromyalgia patients. This is an important population in which mindfulness programs have been evaluated. Fibromyalgia is a common chronic pain syndrome of unknown aetiology. Given the psychological distress, which is often associated with this disease, mindfulness interventions seem especially appropriate for fibromyalgia. The beneficial effects of mindfulness interventions in fibromyalgia patients have been shown in several studies [
20‐
23]. The aim of this study was to investigate the factor structure, reliability (internal consistency and test–retest reliability) and validity (construct validity and incremental validity) of the Dutch version of the FFMQ in patients with fibromyalgia. With regard to construct validity, both constructs incorporating elements of mindfulness (e.g. openness to experiences, acceptance) and constructs reflecting the absence of mindfulness (e.g. alexithymia, neuroticism) were included to assess convergent validity. Furthermore, constructs which were predicted to be weakly or not related to mindfulness (e.g. physical health) were used to assess discriminant validity. To determine the incremental validity, the relation of the different mindfulness facets with mental health and psychological symptoms (depression and anxiety) was assessed.
Discussion
The aim of this study was to investigate the psychometric properties of the Dutch FFMQ in patients with fibromyalgia. Factor structure, internal consistency, test–retest reliability, construct validity and incremental validity in predicting mental health, depression and anxiety were examined. In general, the results of our study were promising and satisfactory.
CFA showed acceptable model fit for a correlated five-factor structure of the FFMQ. This result is in accordance with the results of the original validations of the FFMQ [
2,
19] and assumes that the FFMQ measures five distinct, but related facets of mindfulness. Model fit was less when a hierarchical five-factor structure was used. This is not surprising given the poor loading of the observe facet on the overall mindfulness construct. The latter might be explained by the lack of meditation experience in our study sample [
2,
19].
Although the model fit for a correlated five-factor structure was acceptable, the observe (items 1 and 11) and nonreact (items 4 and 21) facets contained some items with low factor loadings (<0.40), meaning that these items contributed minimally to their underlying facet. Nevertheless, internal consistency of these facets, expressed with Cronbach’s
α coefficient, is considered sufficient for research purposes. These low factor loadings, compared with the findings of Baer et al. [
2], might be explained by cultural differences or differences between the study samples (psychology students and experienced meditators versus fibromyalgia patients). Future research should address whether these items will also be problematic in other clinical and nonclinical populations and if adaptation of the FFMQ is necessary.
This is the first study that examined the test–retest reliability of the FFMQ. Our analyses showed good to excellent results. Findings are in accordance with the results reported on the test–retest reliability of other mindfulness questionnaires, like the KIMS [
16] and the MAAS [
1].
Construct validity was excellent, as shown by the correlations between mindfulness facets and theoretically related (e.g. openness to experiences, acceptance, alexithymia and neuroticism) and unrelated (physical health) constructs. All correlations were in the expected direction and strength, except for the correlation between the describe facet and openness to experiences, which was moderate (
r = 0.35) instead of small (
r < 0.30), and the correlation between the observe facet and alexithymia, which was small (
r = −0.24) instead of weak (−0.10 >
r < 0.10). Theoretically, these findings are not surprising. Compared to the findings of Baer et al. [
2], these correlations are remarkable however. With respect to these findings, we have to note that generally all correlations between mindfulness facets and theoretically related constructs in the study of Baer et al. [
2] were lower than the correlations we found. Differences might be explained by cultural differences, differences in the study sample (psychology students versus fibromyalgia patients) or differences in meditation experience. Hypotheses about which facets should most strongly correlate with each construct were confirmed and in accordance with the results of Baer et al. [
2].
Regression analyses showed that the actaware and nonjudge facets had incremental validity over the others in the prediction of mental health, depression and anxiety. Furthermore, the nonjudge facet appeared a significant predictor of anxiety. These facets independently explained a proportion of the variance that was not explained by the others. This finding is in accordance with the results of Baer et al. [
2]. The actaware facet seemed to be the most important facet in the prediction of mental health and psychological symptoms. This facet remained significantly related with mental health, depression and anxiety (
p < 0.01) after controlling for acceptance, neuroticism, openness and alexithymia. The other facets lost their significance when these variables were added to the model. All facets together explained respectively 44%, 38% and 57% of the variance in mental health, depression and anxiety, indicating that mindfulness is highly related with mental health and psychological symptoms. The direction of this relationship, however, cannot be deduced from the results of our cross-sectional study. Future research should address the causality of the relationship with mental health and psychological symptoms in a longitudinal study design.
This is the first study that validated the FFMQ in a clinical population. Facet scores were higher than the scores reported by Baer et al. [
19] in a community sample. At present, norm scores for a Dutch community sample are not available yet. Therefore, it was not possible to make a statistical comparison between both samples. Future research should reveal if mindfulness scores are really higher in clinical sample compared to a community sample.
A limitation of this study is that we did not assess the amount of meditation experience of the participants. Baer et al. showed that the factor structure of the FFMQ and the relationship of the observe facet with theoretically related constructs change as a function of meditation experience [
2,
19]. Only in participants with meditation experience the observe facet becomes a clear facet of mindfulness and acts like the other facets in relation to other constructs. Our study sample was recruited by self-selection, which might have led to the selection of patients with interest for and/or experience with mindfulness meditation. Nevertheless, we do not expect that the participants had a significant amount of meditation experience, since our results were largely in concordance with the findings of Baer et al. in a predominantly non-meditating student sample [
2]. In future research, the influence of meditation experience should be assessed. Another point concerns the generalizability of the results. Participants seemed representative for the average group of fibromyalgia patients regarding age and gender. Results, however, should be generalized with caution to other groups of clinical patients as well as experienced meditators. Finally, results were obtained with a modified version of the FFMQ. Although differences with the original version of the FFMQ were minimal and the meaning of the items was not changed, results should be generalized with caution to the original translation of the Dutch FFMQ.
All in all, this study shows that the FFMQ is a reliable and valid measure to assess mindfulness in patients with fibromyalgia. With the current study design, it was not possible to investigate sensitivity to change. Future studies should reveal if the FFMQ is also sensitive to detect changes over time. Finally, our results support the multifaceted structure of mindfulness, as earlier suggested [
2], and the usefulness of differentiating between facets in examining the relationship between mindfulness and related constructs. The observe facet, however, should be used with caution in a non-meditating sample, given its deviant relationship with the other facets and theoretically related constructs.