Published in:

International Journal of Behavioral Medicine (2016) DOI: 10.1007/s12529-016-9539-x

Title: A validation and generality study of the Committed Action Questionnaire in a Swedish

sample with chronic pain

Sophia Åkerblom1,2; Sean Perrin2; Marcelo Rivano Fischer1,4; Lance M McCracken3

1Department of Pain Rehabilitation, Skåne University Hospital, Lund, Sweden 2Department of Psychology, Lund University, Lund, Sweden3King's College London, Psychology Department, Health Psychology Section, UK4Department of Health Sciences, Lund University, Lund, Sweden

Contact information for the corresponding authorSophia ÅkerblomDepartment of PsychologyLund UniversityBox 213, 221 00 Lund, SwedenEmail: sophia.akerblom@psy.lu.sePhone: +46(0)46-172-610Mobile: +46-707-790-415

Abstract

Purpose: Psychological flexibility is the theoretical model that underpins Acceptance

Commitment Therapy (ACT). There is a growing body of evidence indicating that ACT is an

effective treatment for chronic pain but one component of the model, committed action, has

not been sufficiently researched. The purpose of this study is to validate Swedish-language

versions of the full length CAQ (CAQ-18) and the shortened CAQ (CAQ-8), to examine the

generality of previous results related to committed action and to further demonstrate the

relevance of this construct to the functioning of patients with chronic pain.

Methods: The study includes preliminary analyses of the reliability and validity of the CAQ.

Participants were 462 consecutive referrals to the Pain Rehabilitation Unit at Skåne

University Hospital.

Results: The Swedish-language version of the CAQ (CAQ-18 and CAQ-8) demonstrated

high levels of internal consistency and satisfactory relationships with various indices of

patient functioning and theoretically related concepts. Confirmatory factor analyses showed

that the factor structure in the current sample matched the two-factor model found in the

original validation studies. Hierarchical regression analyses identified committed action as a

significant contributor to explained variance in patient functioning.

Conclusions: The development, translation and further validation of the CAQ is an important

step forward in evaluating the utility of the psychological flexibility model to the treatment of

chronic pain. The CAQ can both assist researchers interested in mediators of chronic pain

treatment and further enable research on change processes within the psychological flexibility

model.

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Keywords

Committed action questionnaire, chronic pain, psychological flexibility, psychometric

properties, assessment

Introduction

Acceptance and Commitment Therapy (ACT) is establishing itself as an effective treatment

approach for chronic pain (1). The core therapeutic focus of ACT is on psychological

flexibility (2). The psychological flexibility model includes acting in accordance with

personal goals and values, in the presence of potentially interfering thoughts and feelings,

without being unnecessarily limited by these thoughts and feelings, and with a greater

appreciation of what their current situation or context allows (3). Questionnaires have been

developed or adopted to measure several components within the model, such as acceptance

(4), present-focused awareness (5), cognitive defusion (6), values (7), and numerous studies

have shown that these components underlie improvement in treatment of chronic pain (8-13).

Committed action is a component of psychological flexibility that has not been investigated to

a large extent (14). Committed action can be defined as flexible persistent behaviour patterns

directed towards values and goals. They are persistent in the sense that specific actions can

include failure and discomfort and still continue. They are flexible in that, if they are reliably

experienced as unsuccessful, they can change (14). It has been argued that a focus on

committed action may create an advance in understanding around “activity

pacing”,“overactivity”, “underactivity”, and other activity-related concepts commonly applied

in cognitive behavioural therapy for chronic pain (14, 15).

In an attempt to more fully measure psychological flexibility McCracken (2013) developed

the first measure of committed action, the Committed Action Questionnaire (CAQ). (14) A

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shortened version CAQ-8 has also been developed. (15). Both the original and the shortened

version revealed satisfactory reliability and validity

The purpose of this study is to validate Swedish-language versions of the full length CAQ

(CAQ-18) and the shortened CAQ (CAQ-8), to examine the generality of previous results

related to committed action and to further demonstrate the relevance of this construct to the

functioning of patients with chronic pain. The study includes preliminary analyses of the

reliability and validity of both measures. Internal consistency of the CAQ and model fit of

the proposed factor structure will be assessed. The criterion and construct validity of the CAQ

will be explored by assessing its relationship with patient functioning and the theoretically

related concepts pain acceptance and psychological flexibility. Also, the unique contribution

of the CAQ within the overall psychological flexibility model is investigated. The incremental

validity is explored by investigating whether the CAQ is able to account for variance in

patient functioning over and above the effect of pain acceptance and kinesiophobia. The

validity analyses in this study are intended to expand the results from the original validation

studies since comparisons include kinesiophobia, an additional construct that is also highly

relevant for in chronic pain. (16) As there are only three previous studies of the CAQ, and two

of these were conducted in the same treatment center in the UK, the current study represents

an important test of the generality of these previous results. (14, 15, 17). Results are expected

to support the usefulness of both versions of the measure for further research within the field

of chronic pain.

Three hypotheses were tested in the present study. Firstly, significant relationships were

expected between the CAQ and the construct as well as the criterion variables, consistent with

a potential role of committed action as a contributor to healthy functioning. Based on previous

research and the psychological flexibility model, at least moderate positive correlations were

expected between the CAQ and pain acceptance and psychological flexibility. Moreover,

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moderate negative correlations were expected between the CAQ and depression and anxiety.

Moderate positive correlations were expected with vitality, social functioning, general health

and mental health and a small positive correlation with physical functioning. (3, 14, 18)

Secondly, again in line with the psychological flexibility model involving several related but

distinct constructs that contribute to psychological flexibility, the CAQ was expected to make

a significant contribution to explaining the variance in psychological flexibility together with

pain acceptance. Thirdly, the CAQ was expected to make a significant contribution to

explaining the variance in patient functioning after accounting for the contribution of pain

acceptance and kinesiophobia. (3, 18)

Methods

Participants

Participants were 462 consecutive referrals scheduled for assessment at the Pain

Rehabilitation Unit at Skåne University Hospital between August 2013 and January 2015.

The unit is a government supported, regional specialist center where patients are admitted if

they have symptoms of chronic pain that impacts significantly on everyday life. Patients

admitted to the clinic and who meet eligibility requirements are offered intensive, multi-

disciplinary, day treatment based on a cognitive behavioral model. All participants gave

written informed consent prior to their data being used in the study. The study was approved

by the Regional Ethical Review Board in Lund, Sweden (2013/381).

The sample consisted of 333 women (72.1 %) and 129 men aged between 18 and 67 years (M

= 41.0, SD = 11.2). About half (51.9%) were currently in work or studying at least on a part-

time basis. The majority (74.9%) were born in Sweden or another Nordic country. Slightly

more than half (53.9 %) had upper secondary school as their highest education level with a

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further 26.4 % having studied at university level. These demographics are similar to those

reported by tertiary pain clinics in the 2015 report from the Swedish Quality Registry for Pain

Rehabilitation (i.e., 76% of patients are women and 25% have studied at university level)

(19). The most common diagnoses were fibromyalgia (25.9 %), cervicocranial syndrome

(11.7 %), cervicobrachial syndrome (8.3 %) and myalgia (6.2 %). The average duration of

pain was 7.6 years (SD =7.6) with the number of pain locations varying between 1 and 36 (M

= 14.9, SD = 8.9). Average pain intensity over the past week (rated on a 0-10 scale) was 7.5

(SD = 1.5).

Translation of the CAQ

In translating and back-translating the measure, we followed internationally recommended

guidelines (20). Briefly, the CAQ was first translated from English to Swedish by a Swedish

clinical psychologist fluent in English and with specific knowledge of the research area. The

questionnaire was then back-translated by a Swedish psychologist fluent in English and with

experience in working with instrument translation and validation. Thereafter the translated

and back-translated versions were evaluated by an ‘expert’ group comprised of clinical

psychologists working in the field of pain rehabilitation who were fluent in Swedish and

English, as well as the author of the English language original. The questionnaire was updated

and changed according to suggestions of the expert group. In the penultimate step, the ‘final’

Swedish language version of the CAQ was administered to 10 current patients at the pain

clinic and they were asked to give feedback on the clarity of instructions and the vocabulary

used. Final adjustments were made and the updated version was then approved by the expert

group and administered to new referrals as part of a larger package of standardized

questionnaires.

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Measures

Self-report data were collected by mailing measures to the homes of newly referred patients to

be completed before their first full clinical assessment (diagnosis, functioning, and suitability

for treatment) at the clinic. In addition to the measures listed below, patients reported their

age, gender, education, country of birth, marital status, work status, pain sites, and pain

duration.

Committed Action Questionnaire (CAQ-18): The CAQ measures goal-directed, flexible

persistence and has 18 items each rated on a seven-point scale (0 = never true to 6 = always

true) (14). The CAQ has two components, derived from factor analysis and based on how the

items are phrased: Factor 1consists of nine positively phrased items (e.g., “When I fail in

reaching a goal, I can change how I approach it”) and Factor 2 of nine negatively phrased

items (e.g., “When I fail to achieve what I want to do, I make a point to never do that again”)

(14). All items are summed (negatively phrased items need to be reversed first) to arrive at a

total score (range = 0-108). The original validation study found the CAQ to have satisfactory

internal consistency and validity (14). The reliability and validity of a translated Swedish

version was tested in this study.

Committed Action Questionnaire (shortened version) (CAQ-8): The CAQ-8 has two

components, one positively phrased and one negatively phrased, with 4 items each. The total

score of the scale is 48. As the original the shortened version has strong reliability and

validity. (15).The reliability and validity of a translated Swedish version was tested in this

study.

Chronic Pain Acceptance Questionnaire (CPAQ): The CPAQ assesses another component of

the psychological flexibility model, namely acceptance, in people with chronic pain (21). This

self-report measure is comprised of 20 items rated on a 7-point scale (0 = never true; 6 =

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always true) and includes two subscales: activity engagement and pain willingness. Higher

total and subscale scores reflects greater acceptance. The English language version of the

CPAQ has good internal reliability (α = 0.74), a stable factor structure and correlates

significantly with measures of pain-related functioning (4, 21). The Swedish version of the

CPAQ used in this study has satisfactory internal reliability (α = 0.91) and correlates well

with measures of pain functioning (16). The CPAQ was used to investigate the construct

validity of the CAQ.

Hospital Anxiety and Depression Scale (HADS): The HADS is a commonly used, 14-item

self-report measure designed to detect symptoms of anxiety and depression (separately)

amongst patients in a medical setting (22). The anxiety and depression subscales each contain

seven items rated on a four-point scale (0 to 3), with higher scores indicating greater severity.

Consistent with the English original, the Swedish version used in this study has been shown to

have excellent internal reliability for the total (α = 0.90), anxiety (α = 0.84) and depression

scales (α = 0.82) and to correlate significantly with alternate measures of anxiety and

depression (23). The HADS was used to investigate the criterion validity of the CAQ.

Medical Outcomes Study Short Form 36-Item Health Survey (SF-36): This is a self-report

measure of non-disease-specific health and functioning widely used in health research (24).

The 36 items are used to compute 8 subscales scores. The following subscales were used in

this study: physical functioning -10 items, vitality - 4 items, mental health - 5 items, social

functioning -2 items, and general health - 5 items. All subscales are transformed to a 0-100

scale with higher scores indicate a greater health state. Like the English original, the Swedish

version used in this study has been shown to have excellent internal reliability for the

subscales (α = 0.79 to 0.91) and validity when compared with other measures of health

functioning (24, 25). The SF-36 was used to investigate the criterion validity of the CAQ.

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Psychological Inflexibility in Pain Scale (PIPS): The PIPS measures psychological

inflexibility in relation to chronic pain. It is a self-report measure with 12 items rated on a 7-

point scale (1= never true; 7 = always true) and includes two subscales cognitive fusion

related to pain and avoidance of pain. Higher scores indicate greater psychological

inflexibility and the maximum score is 84. The scale has satisfactory psychometric

properties(α = 0.87).(6) The PIPS was used to investigate the construct validity of the CAQ.

Tampa Scale of Kinesiophobia (TSK): The TSK assesses fear of (re)injury by physical

movement or activity. This self-report measure has 17 items rated on a 4-point scale (1 =

strongly disagree; 4 =strongly agree). The total score has a range from 17 to 68 and higher

scores indicate higher pain-related fear. The TSK has been shown to have satisfactory

psychometric properties (α = 0.75) and a Swedish version was used in this study.(26-28).

Statistical approach

All CAQ items were investigated for missing data and frequency distribution. Reliability was

estimated in several ways including via inter-item correlations, item-total correlations and

Cronbach’s alpha, where a score of 0.70 or higher was considered acceptable (29).

Confirmatory factor analysis (CFA) was used to investigate whether the factor structure in the

current sample matched the two-factor models found in the original validation studies. For

cross-validation purposes confirmatory factor analysis is preferred over exploratory factor

analysis since CFA tests the degree to which a hypothesized factor structure matches the

pattern of covariances among the scale´s items (30, 31). Items were considered for removal if

the corrected item-total correlation was below r= 0.30 (29) or the item loading (standardized

regression weights) was below .32. (32)The analysis was conducted using maximum

likelihood estimation and goodness of fit was evaluated by: the relative/normed Chi-Square

statistic (x2/df; acceptable fit<5) (31), Tucker–Lewis Index (TLI; acceptable fit≥ 0.95) (32),

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the Root Mean Square Error of Approximation (RMSEA) and the Comparative Fit Index

(CFI; adequate fit > .90, good fit > .95) (33, 34). The relative/normed Chi-Square (χ2/df) was

used instead of the traditional Chi-Square value together with the associated p-value because

it reduces the likelihood of falsely rejecting the model when one has large sample sizes as in

the present study (33). RMSEA is a well-established fit statistic which can be considered one

of the most informative. Recommendations for cut-off points have varied over the years. (33,

34) Frequently reported cut-offs include “close fit” < 0.05, “reasonable fit” <.08, and

“mediocre fit” < 0.10 (35). The sample size of 462 was deemed satisfactory according to

established guidelines for factor analysis. (36-39)

Criterion validity was investigated in the form of “concurrent validity,” as all measures were

collected at the same time. Pearson correlation coefficients were calculated and all

correlations were evaluated as strong (.5- 1.0), moderate (.3-.5) or small (.1-.3).(40)

Correlation analyses of the CAQ-18 and CAQ-8 were conducted in relation to background

variables as well as the criterion variables, which included depression and anxiety (HADS)

and health and functioning (SF-36). Additional correlations between pain acceptance (CPAQ)

and the same background and criterion measures were examined to evaluate the performance

of the CAQ-18 and CAQ-8 in comparison to a well-known measure from the same

psychological flexibility model. Also, correlations between kinesiophobia (TSK) and the

same background and criterion variables were performed to be able to compare the

performance of CAQ-18 and CAQ-8 in relation to an independent construct, which is

considered highly relevant for in chronic pain.(16)

The relationships between the CAQ (CAQ-18 and CAQ-8), CPAQ and psychological

flexibility (PIPS) were also examined and can be considered tests of construct validity, since

these are theoretically related measures specified within the psychological flexibility model

and predicted to correlate. (3, 18) Regression analysis was performed to determine if CPAQ

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and CAQ were significant contributors to PIPS, which measures psychological flexibility the

overarching process within the psychological flexibility model. According to the model

acceptance and committed action are supposed to contribute to psychological flexibility

together with four other processes. (3, 18)

To examine the incremental validity of the CAQ a series of regression analyses were

undertaken. It was investigated whether the CAQ (CAQ-18 and CAQ-8) was able to account

for variance in patient functioning over and above the effect of CPAQ and TSK. The

regression analyses were done hierarchically. For each dependent variable two models were

tested; the first included background information and CAQ only, and the second included

background information, CPAQ, TSK, and CAQ. Seven indices of patient functioning were

used as dependent variables: depression and anxiety (HADS); physical functioning, social

functioning, vitality, mental health, and general health (SF-36). The effects of background

variables (age, gender, and education) were examined for each dependent variable and

included in the regression analyses if significant at p < .01. The significant background

variables were entered first (Step 1) followed by CAQ (Step 2) in the first model. In the

second model significant background variables were entered first followed by CPAQ (Step 2),

TSK (Step 3) and CAQ (Step 4). All analyses were conducted using SPSS and AMOS

(Version 22).

Results

Descriptive and attrition analyses

Of the 462 participants 157 (34 %) had missing data, in these cases due to the patient failing

to complete a particular measure or item. In attempting to deal with missing data we adhered

to recommended statistical procedures.(41, 42) Missing values analyses indicated that data

was missing completely at random (Little’sMCAR test: Chi-square = 2024.3, df = 2015, p

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= .438) and the average percentage of missing data in the variables was only 1.80 %.

Consequently, it was deemed suitable to keep all cases in the analyses and impute missing

values with the Expectation-maximization (EM) method. (42, 43)

Item-analysis

All 18 items of the CAQ had response rates above 97.1%. Visual inspection of histograms,

normal Q-Q plots and boxplots ensured that all items were approximately normally

distributed. Outliers (n=40) were identified by computing standardized scores using absolute

Z values larger than 3 as a cut off. The affected values of the outliers were winsorized and

consequently included in all analyses(44). The observed mean for the CAQ-18 total was 59.9

(SD = 16.4) and for the CAQ-8 was 26.3 (SD=8.5). All items correlated with each other with

no inter-item correlation above r=0.66. All item-total correlations were greater than r = .30

(range = .36 to .69), except for item 9 from the CAQ-18 (“I get stuck doing the same thing

over and over even if I am not successful”; r = .13). The observed Cronbach alphas for CAQ-

18 were α = .89 (CAQ Total), α = .90 (positively framed item factor), and α = .80 (negatively

framed item factor). The observed Cronbach alphas for CAQ-8 were α = .84 (CAQ Total), α =

.86 (positively framed item factor), and α = .77 (negatively framed item factor).

Confirmatory factor analysis

CFA was used to investigate whether the Swedish translation of the CAQ yielded similar two-

factor models as found in the original validation studies(14, 15). Fit indices are displayed in

Table 1. Taken together, these indicated either satisfactory fit for the 18 item- model

(RMSEA, CFI and x2/df) or values just short of satisfactory (TFI). Modification indices from

the initial model indicated a high level of covariance between Item 1(“I am able to persist

with a course of action after experiencing difficulties”) and Item 2 (“When I fail in reaching a

goal, I can change how I approach it”). To investigate if model fit could be improved one

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supplementary model was tested, where the error terms of these items were allowed to covary.

This adjusted model was deemed appropriate since both items loaded on the same factor and

reflect facing difficulties and continuing with one’s commitments. Permitting this covariance

improved the model fit. For the 8 item- model all fit indices indicated satisfactory fit. Table 2

shows descriptive data and item loadings (standardized regression weights) from the CFA.

They were generally satisfactory for CAQ-18(range for Factor 1 = .55 to .79; range for Factor

2 = .47 to .76). The loading for item 9 (“I get stuck doing the same thing over and over even if

I am not successful”) on Factor 2 was again somewhat weak (.25). However, given the largely

satisfactory match between the model obtained in the current sample and the original

validation study, and the unique and highly face valid content included in this item, we

elected to retain the adjusted 18-item, two factor model. Item loadings (standardized

regression weights) for CAQ-8 were all satisfactory (range for Factor 1=.75 to.79; range for

Factor 2=.61 to .80).

Table 1 Goodness of fit indicesModel 2-factor 18

items2-factor w covaried error (item1-item2)

18 items

2-factor 8 items

x2/df 3.52 3.16 2.97TLI .89 .90 .96

RMSEA(confidence interval)

.07 (.07-.08) .07 (.06-.08) .07 (.05-.09)

CFI .90 .92 .97Notes: Godness of fit indices were: the relative/normed Chi-Square statistic(x2/df; acceptable fit<5); tucker–lewis index (TLI; acceptable fit≥ 0.95); the root mean square error of approximation (RMSEA; close fit < 0.05, reasonable fit <.08, and mediocre fit < 0.10); the comparative fit index (CFI; adequate fit > 0.90, good fit > 0.95)Similar results were obtained using the Scale-free least squares estimator, where the assumption of multivariate normality does not need to be met

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Table 2 Descriptive data and standardized regression weights from the CFA for the 18 items in the Committed Action QuestionnaireItemno

Items Mean (sd)

CAQ-18 CAQ-8Standardized regression weights

Factor 1 (positively phrased)

Factor 2 (negatively

phrased)

Factor1 (positively phrased)

Factor 2 (negatively

phrased) 1 I am able to persist with a course of action

after experiencing difficulties3.15 (.72)

.55

2 When I fail in reaching a goal, I can change how I approach it

3.66 (1.56)

.73

3 (1) I can remain committed to my goals even when there are times that I fail to reach them

3.59 (1.47)

.79 .78

4 (2) When a goal is difficult to reach, I am able to take small steps to reach it

3.77 (1.50)

.79 .81

6 (3) I prefer to change how I approach a goal rather than quit

3.89 (1.49)

.72 .75

7 (4) I am able to follow my long term plans including times when progress is slow

3.65 (1.54)

.77 .79

12 I am able to pursue my goals both when this feels easy and when it feels difficult

3.27 (1.55)

.77

13 I am able to persist in what I am doing or to change what I am doing depending on what helps me reach my goals

3.61 (1.38)

.68

15 I am able to incorporate discouraging experiences into the process of pursuing my long term plans

4,01 (1.36)

.62

5 I act impulsively when I feel under pressure

2.65 (1.69)

.47

8 When I fail to achieve what I want to do, I make a point to never do that again

3.68 (1.60)

.51

9 I get stuck doing the same thing over and over even if I am not successful

3.64 (1.50)

.25

10 (5) I find it difficult to carry on with an activity unless I experience that it is successful

2.53 (1.59)

.64 .61

11 I am more likely to be guided by what I feel than by my goals

2.58 (1.49)

.60

14 If I make a commitment and later fail to reach it, I then drop the commitment

3.33 (1.50)

.49

16 (6) If I feel distressed or discouraged, I let my commitments slide

2.39 (1.51)

.70 .71

17 (7) I get so wrapped up in what I am thinking or feeling that I cannot do the things that matter to me

2.91 (1.67)

.76 .80

18 (8) If I cannot do something my way, I will not do it at all

3.59 (1.63)

.62 .62

Notes: The CFA was conducted using maximum likelihood estimation.

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Factor 1consists of nine positively phrased items and Factor 2 of nine negatively phrased items in the model for CAQ-18Factor 1consists of four positively phrased items and Factor 2 of four negatively phrased items in the model for CAQ-8

Relationship with background and criterion variables

Table 3 presents correlations between the CAQ, background and criterion variables.

Significant correlations were found between the CAQ and all criterion variables (range for

CAQ-18 r=.20-.48, p < .01; range for CAQ-8 r=.16-.47, p < .01). Generally, the associations

were in line with the expectations made in the a priori hypotheses. The correlations between

the CAQ and the criterion/background variables were of comparable magnitude to both those

between the same background/criterion variables and Swedish language versions of the

CPAQ and the TSK. The correlation between the CAQ-18 and the TSK was r=-.35 (p< .01),

the correlation between CAQ-8 and the TSK was r=-.31(p< .01) and the correlation between

the CPAQ and the TSK was r=-.44 (p< .01)

Table 3 Correlations with background and criterion variablesCommitted action

(CAQ-18)Committed action

(CAQ-8)Pain acceptance Kinesiophobia

Background variables

Age -.02 -.04 .04 -.19**Gender .09* .10* .19** .12**

Education .20** .16* .20** -.23**Criterion variables

Depression -.48** -.47** -.54** .37**Anxiety -.47** -.45** -.41** .40**Physical

functioning.20** .16** .27** -.41**

Social functioning

.28** .30** .56** -.27**

Mental health .46** .46** .50** -.44**Vitality .24** .26** .37** -.20**

General health .35** .34** .32** -.40**

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Notes: Pain acceptance was measured with the Chronic Pain Acceptance Questionnaire, committed action with the Committed Action Questionnaire, kinesiophobia with Tampa Scale of Kinesiophobia, depression and anxiety with the Hospital Anxiety and Depression Scale. Physical functioning, social functioning, mental health, vitality and general health were measured with The Medical Outcomes Study Short Form 36-Item Health Survey *P < .05.**P < .01

Regression analyses

When investigating construct validity the correlations were consistent with the relationships

hypothesized a priori. The correlation between the CAQ-18 and the CPAQ was r=.37

(p< .01), the correlation between the CAQ-18 and the PIPS was r=-.48, p< .01) and the

correlation between the CPAQ and the PIPS was r=-.70. The correlations for CAQ-8 and

CPAQ was as r=.35 (p< .01) and the correlation between CAQ-8 and PIPS was r=-.45, p< .01.

The contribution of pain acceptance and committed action to psychological flexibility was

investigated with regression analysis. Using PIPS as a dependent variable, CPAQ and CAQ-

18explained 55 % of the variance (R=.74, R2=.55, Beta (CPAQ)=-.61, t(CPAQ)=-17.95 (p

< .001); Beta(CAQ)=-.25, t(CAQ)=-7.48 (p < .001). The regression analysis was repeated

with CAQ-8 instead of CAQ-18 with similar results.

With regard to incremental validity table 4 presents the results of the hierarchical regression

analyses. In the first step, age, gender and education were examined in relation to each of the

dependent variables (indices of functioning). Background variables were retained in the

subsequent regressions involving that dependent variable if they were found significant. In the

regression models including significant background information and CAQ-18, the CAQ-18

accounted for a significant proportion of the variance in functioning (range 3% to 21%) in six

out of six models. In the regression models including CPAQ, TSK and CAQ-18 as

independent variables, the CAQ-18 accounted for a significant proportion of the variance in

functioning (range = 1% to 8%) in five out of six models. No significant contribution was

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shown in the equation for physical functioning. The same regression analyses were conducted

with CAQ-8 instead of CAQ-18. The shortened version explained as much or more variance

in the analyses.

All relationships between the CAQ and the dependent variables were in the expected

direction; higher levels of committed action were associated with lower depression and

anxiety and better health and functioning. The total explained variance (R2) was relatively

large in several models with more than 30% of the variance in depression, anxiety, social

functioning and mental health explained by pain acceptance, kinesiophobia and committed

action.

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Table 4 Hierarchical regression analyses of patient functioning in relation to pain acceptance and committed action (CAQ-18)

Dependent variable

Block Predictor R R2 R2

changeβ

(final)t

Depression 1 AgeEducation

.20 .04 .04 .12** 2.92-.06 -1.48

2 Committed action .50 .25 .21 -.47** -11.261 Age

Education.20 .04 .04 .09* 2.45

.00 .062 Pain acceptance .55 .30 .26 -.37** -9.293 Kinesiophobia .56 .32 .02 .08 1.774 Committed action .63 .40 .08 -.31** -7.71

Anxiety 1 Education .20 .04 04 -.12** -2.752 Committed action .48 .23 .19 -.45** -10.641 Education .20 .04 04 -.06 -1.502 Pain acceptance .42 .18 .14 -.19** -4.323 Kinesiophobia .48 .23 .05 .19** 4.134 Committed action .56 .31 .08 -.32** -7.42

Physical functioning

1 AgeEducation

.31 .09 .09 -.26** 3.29.15** -5.81

2 Committed action .35 .12 .03 .17** 3.731 Age

Education.31 .09 .09 -.21** -5.02

.08 1.902 Pain acceptance .38 .14 .05 .09 1.943 Kinesiophobia .47 .22 .07 -.31** -6.384 Committed action .47 .22 .00 .04 .85

Social functioning 1 Committed action .28 .08 .08 .28** 6.331 Pain acceptance .56 .31 .31 .52** 11.752 Kinesiophobia .56 .31 .00 -.01 -.323 Committed action .57 .32 .01 .09* 2.06

Mental health 1 Education .15 .02 .02 .06 1.422 Committed action .46 .21 .19 .44** 10.461 Education .15 .02 .02 -.01 -.342 Pain acceptance .50 .25 .23 .31** 7.243 Kinesiophobia .56 .31 .06 -.21** -4.894 Committed action .61 .37 .06 .27** 6.53

Vitality 1 Committed action .24 .06 .06 .24** 5.271 Pain acceptance .37 .14 .14 .32** 6.412 Kinesiophobia .37 .14 .00 -.02 -.463 Committed action .39 .15 .01 .11* 2.40

General health 1 Committed action .35 .12 .12 .35** 7.881 Pain acceptance .32 .10 .10 .12* 2.542 Kinesiophobia .43 .18 .08 -.27** -5.793 Committed action .47 .22 .03 .20** 4.47

17

Notes: Two models were tested for all dependent variables. One included background variables and committed action, and the other included background variables, pain acceptance, kinesiophobia and committed action. Pain acceptance was measured with the Chronic Pain Acceptance Questionnaire, committed action with the Committed Action Questionnaire, kinesiophobia with Tampa Scale of Kinesiophobia, depression and anxiety with the Hospital Anxiety and Depression Scale. Physical functioning, social functioning, mental health, vitality and general health were measured with The Medical Outcomes Study Short Form 36-Item Health Survey *p < .05**P < .01

Discussion

Psychological flexibility as a model concerns itself with the capacity to persist with or change

behavior to serve one´s goals in a context of psychological influence and situational prospects

(14). As applied to chronic pain, the model emphasizes helping patients to take actions that

are consistent with their personal goals and contribute to their overall wellbeing and

functioning. Within this model these actions are meant to have certain qualities, they are done

with openness and awareness of experiences such as pain, anxiety or depression, while at the

same time not unduly governed by these experiences. One specific element within this model

is committed action, conceptualized essentially as flexible, sensitive, behavioral persistence.

Recently, an 18-item English language measure of committed action was developed – the

Committed Action Questionnaire (CAQ).(14) A shortened version (CAQ-8) has also been

developed.(15) The purpose of the present study was to validate the original and the shortened

version of the CAQ in Swedish, to examine the generality of previous results related to

committed action and to further demonstrate the relevance of this construct to the functioning

of patients with chronic pain.

All a priori hypotheses in the study were supported and the translated versions of the CAQ

were found to have satisfactory psychometric properties in the sample of Swedish chronic

pain patients examined in this study. First, both versions of the CAQ yielded high levels of

internal consistency and reliability. Second, we were able to retain all items of the measures

and fit the two factor models, suggested in the original validation studies, to the observed data

with only the slightest modification. Third, taken together the CAQ demonstrated good

18

concurrent validity. Pair-wise correlations between these versions of the CAQ and various

background variables and indices of patient functioning were generally significant and of the

expected magnitudes. The magnitudes of the correlations were also comparable to those

between the Swedish language version of the CPAQ and the TSK and these same

background/criterion variables. Fourth, the significant correlations with the theoretically-

related measures of pain acceptance and psychological flexibility provided support for the

construct validity of the CAQ. Furthermore, the CAQ was identified a significant contributor

to psychological flexibility, the overarching process within the psychological flexibility

model. Finally, hierarchical regression analyses supported the incremental validity of the

CAQ since it was shown that the measure made a significant contribution to explaining the

variance in overall functioning, particularly depression and anxiety, after accounting for the

contribution of pain acceptance and kinesiophobia. All in all, these findings provide

preliminary support for the validity of the Swedish language versions of the CAQ, support the

reliability and generality of the earlier findings to another context, support the relevance of

this construct to the functioning of patients with chronic pain and further support the notion

that the various components of psychological flexibility work together to help explain

functioning in pain patients.

The findings from this study are in line with a large number of studies that have shown that

key processes identified in the psychological flexibility model are significantly related to the

functioning of people with chronic pain (8-13, 45). Further, they strengthen earlier findings

with regard to the relatively newly researched facet of psychological flexibility, i.e.,

committed action (14, 15, 17, 46). Currently, all six key processes of psychological flexibility

have empirical support within the field of chronic pain. Specifically, acceptance (4, 8-10, 16,

45, 47-60) and value-based action (7, 9, 57, 61-63) have strong empirical support, and the

19

less studied processes of committed action (14, 15, 17, 64), present-focused awareness (9, 61,

65), cognitive defusion (6, 12) and self-as-observer (66) have all received preliminary

support in explaining functioning in pain patients. The development and further validation of

the CAQ is an important step forward in evaluating the utility of the psychological flexibility

model to the treatment of chronic pain. Much of the previous research into psychological

flexibility has focused on the openness and awareness components, and less on the activation,

engagement, goals, and motivation components, which can now be more fully addressed (15,

18). Future studies will need to further examine these less studied processes, including within

different national contexts and cultures.

Current psychological treatments for chronic pain only produce small to medium effect sizes.

Hence, these treatments can be improved. Up until now studies have not revealed which

processes and methods are most effective or necessary in improving outcome. Identification

of “active processes” or mediators of outcome could be used to refine treatments (67, 68). The

psychological flexibility model, including committed action, has been identified as a potential

framework for understanding change processes during chronic pain treatment. It has been

argued that its theoretical base, philosophical principles and scientific strategy could guide

future research activity in a consistent fashion A major strength of the model is that it

specifies six processes (mediators) which facilitate change during treatment(18). One of these

processes is committed action. Consequently, the development and translation of the CAQ

can assist researchers interested in treatment development through identification of mediators

of chronic pain treatment, and particularly mediators based in the psychological flexibility

model. Additionally, it can help clinicians when assessing the strength and workability of

their interventions and treatment programs during or after treatment.

Findings from the present study must be viewed within the context of certain limitations. All

findings are based on patient self-reports obtained at one point in time and without reference

20

to a control group. Second, the while the obtained results were similar to the original

validation studies, the findings from all these studies are based on chronic patients seeking

treatment from highly specialist pain services and results may not generalize to other samples.

(14, 15) Third, the present sample was comprised primarily by women with a high percentage

of participants having university-level education. While this may make the sample less

representative of chronic pain patients generally, we note that the unique quality of the current

sample and its dissimilarity to the samples included in the original validation studies of the

CAQ lend greater support for the generality of the findings. (14, 15) Fourth, the variance in

functioning accounted for by the CAQ varied greatly across the measures of functioning and

one relation was non-significant (physical functioning). Future controlled longitudinal studies

are needed to clarify the relative contribution of committed action to functioning and

treatment outcome. Fifth, all relevant psychometric properties have not been investigated in

this study. Future studies could complement the analyses by examining sensitivity to change

and other validity indicators.

A final caveat is worth mentioning. The six processes specified in psychological flexibility,

including committed action, represent current tools for further investigation and clinical

development. While they are abstracted or translated to a degree from a set of basic

behavioral principles, mostly from within contextual behavioral research, they are not

themselves precise technical terms directly generated from experimental laboratories. They

are often referred to a “midlevel” terms as their function is to link the language of clinicians to

the language of basic researchers (3). It is important for future progress that these terms not be

reified and to recognize that one day these will appear limited and will likely change.

In sum, this study supports the validity and reliability of these Swedish language versions of

the CAQ, the generality of the earlier findings and the relevance of committed action to

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functioning in chronic pain patients. The CAQ may be a useful tool for investigating

mediators or “active” processes of change in treatment for chronic pain.

Acknowledgements

We are grateful to Katarina Lundberg and the psychologists at the Department of Pain

Rehabilitation, Skåne University Hospital for their contributions during the measure

translation.

Ethical approval

All procedures performed in this study were in accordance with the ethical standards of the

institutional and/or national research committee and with the 1964 Helsinki declaration and its

later amendments or comparable ethical standards.

Funding

No funding sources were provided.

Conflicts of interest

The authors declare that they have no conflict of interest.

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References

1. Hann KE, McCracken LM. A systematic review of randomized controlled trials of Acceptance and Commitment Therapy for adults with chronic pain: Outcome domains, design quality, and efficacy. Journal of Contextual Behavioral Science. 2014;3(4):217-27. 2. Hayes SC, Strosahl K, Wilson KG. Acceptance and commitment therapy : an experiential approach to behavior change. New York ; London: Guilford Press; 1999.3. Hayes SC, Strosahl KD, Wilson KG. Acceptance and Commitment Therapy: The Process and Practice of Mindful

Change. London: Guilford Press; 2012.4. Vowles KE, McCracken LM, McLeod C, Eccleston C. The Chronic Pain Acceptance Questionnaire: Confirmatory factor analysis and identification of patient subgroups. Pain. 2008;140(2):284-91. doi:10.1016/j.pain.2008.08.0125. Brown KW, Ryan RM. The benefits of being present: mindfulness and its role in psycholological well-being. Jornal of Personality and Social Psychology. 2003;84(1):822-48. 6. Wicksell RK, Lekander M, Sorjonen K, Olsson GL. The Psychological Inflexibility in Pain Scale (PIPS) - Statistical properties and model fit of an instrument to assess change processes in pain related disability. European Journal of Pain. 2010;14(7):771.e1–.e14. 7. McCracken LM, Yang SY. The role of values in a contextual cognitive-behavioral approach to chronic pain. Pain. 2006;123(1-2):137-45. doi:10.1016/j.pain.2006.02.0218. Baranoff J, Hanrahan SJ, Kapur D, Connor JP. Acceptance as a process variable in relation to catastrophizing

in multidisciplinary pain treatment. European Journal of Pain. 2013; 17:101–10 doi:10.1002/j.1532-2149.2012.00165.x9. Vowles KE, Wetherell JL, Sorrell JT. Targeting Acceptance, Mindfulness, and Values-Based Action in Chronic Pain: Findings of Two Preliminary Trials of an Outpatient Group-Based Intervention. Cognitive and Behavioral Practice. 2009;16(1):49-58. doi:10.1016/j.cbpra.2008.08.00110. McCracken LM, Gutiérrez-Martínez O. Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on Acceptance and Commitment Therapy. Behaviour Research and Therapy. 2011;49(4):267-74. doi:10.1016/j.brat.2011.02.00411. Vowles KE, Witkiewitz K, Sowden G, Ashworth J. Acceptance and commitment therapy for chronic pain: Evidence of mediation and clinically significant change following an abbreviated interdisciplinary program of rehabilitation. The Journal of Pain. 2014;15(1):101-13. doi:10.1016/j.jpain.2013.10.00212. Wicksell RK, Olsson GL, Hayes SC. Psychological flexibility as a mediator of improvement in Acceptance and Commitment Therapy for patients with chronic pain following whiplash. European Journal of Pain. 2010;14(10):1059.e1-.e11. doi:10.1016/j.ejpain.2010.05.00113. Åkerblom S, Perrin S, Rivano Fischer M, McCracken LM. Original Report: The Mediating Role of Acceptance in Multidisciplinary Cognitive-Behavioral Therapy for Chronic Pain. Journal of Pain. 2015. doi:10.1016/j.jpain.2015.03.007

23

14. McCracken LM. Committed action: An application of the psychological flexibility model to activity patterns in chronic pain. Journal of Pain. 2013;14 (8):828-35. doi:10.1016/j.jpain.2013.02.00915. McCracken LM, Chilcot J, Norton S. Further development in the assessment of psychological flexibility: A shortened committed action questionnaire (caq 8). European Journal of ‐Pain. 2014. doi:doi: 10.1002/ejp.58916. Wicksell RK, Olsson GL, Melin L. The Chronic Pain Acceptance Questionnaire (CPAQ)-further validation including a confirmatory factor analysis and a comparison with the Tampa Scale of Kinesiophobia. European Journal of Pain. 2009;13(7):760-8. doi:10.1016/j.ejpain.2008.09.00317. Wong W-s, McCracken L, Wong S, Chen P-p, Chow Y-f, Fielding R. The Chinese Version of the 8-Item Committed Action Questionnaire (ChCAQ-8): A Preliminary Analysis of the Factorial and Criterion Validity. Psychological Assessment. 2015. doi:10.1037/pas0000187

10.1037/pas0000187.supp (Supplemental)18. McCracken LM, Morley S. The psychological flexibility model: A basis for integration and progress in psychological approaches to chronic pain management. Journal of Pain. 2014;15(3):221-34. doi:10.1016/j.jpain.2013.10.01419. Rehabilitation SQRfP. Årsrapport 2015 (Internet). Swedish Quality Registry for Pain Rehabilitation. 2015. http://www.ucr.uu.se/nrs/index.php/arsrapporter. Accessed Sep 25th 2015.20. Beaton DE, Bombardier C, Guillemin F, Ferraz MB. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine. 2000;25(24): 3186-91. 21. McCracken LM, Vowles KE, Eccleston C. Acceptance of chronic pain: Component analysis and a revised assessment method. Pain. 2004;107(1-2):159-66. doi:10.1016/j.pain.2003.10.01222. Zigmond AS, Snaith RP. The Hospital Anxiety and Depression Scale. Acta Psychiat Scand. 1983;67(6):361-70. doi:DOI 10.1111/j.1600-0447.1983.tb09716.x23. Lisspers J, Nygren A, Soderman E. Hospital Anxiety and Depression Scale (HAD): some psychometric data for a Swedish sample Acta Psychiat Scand. 1997; 96 281-6. 24. Ware JE, Sherbourne CD. The MOS 36-Item Short-Form Health Survey (SF-36): I. Conceptual Framework and Item Selection. Medical Care. 1998;36(5):752-6. 25. Sullivan M, Karlsson J, Ware Jr JE. The Swedish SF-36 Health Survey-I. Evaluation of data quality, scaling assumptions, reliability and construct validity across general populations in Sweden. Social Science and Medicine. 1995;41(10):1349-58. 26. Swinkels-Meewisse EJ, Roelofs, J., Verbeek, A.L.M., Oostendorp, R.A.B., Vlaeyen, J.W.S. . Fear of movement/(re)injury, disability and participation in acute low back pain. Pain. 2003;105 371–9.

27. Vlaeyen JWS, Kole-Snijders, A.M.J. ., Boeren, R.G.B., Van Eek, H. . Fear of movement/ (re)injury in chronic low back pain and its relation to behavioral performance. Pain. 1995;62 363–72. 28. Roelofs J SJ, Frings-Dresen MH, Goossens M, Thibault P, Boersma K, Vlaeyen JW. Fear of movement and (re)injury in chronic musculoskeletal pain: Evidence for an invariant two-factor model of the Tampa Scale for Kinesiophobia across pain diagnoses and Dutch, Swedish, and Canadian samples. Pain. 2007 131(1-2):181-90. 29. Nunnally J, Bernstein I. Psychometric Theory,. 3

ed. New York, NY: McGraw Hill; 1994.30. Watkins D. The role of confirmatory factor analysis in cross-cultural research. International Journal of Psychology. 1989;24(6):685-701. 31. van Prooijen J, van der Kloot WA. Confirmatory Analysis of Exploratively Obtained Factor Structures. Educational and Psychological Measurement. 2001;61(5):777-92. 32. Tabachnick BG, Fidell LS. Using multivariate statistics / Barbara G. Tabachnik, Linda S. Fidell: Boston, Mass. ; London : Pearson Education, cop. 2013

24

6th ed.; 2013.33. Hooper D, Coughlan J, Mullen MR. Structural Equation Modelling: Guidelines for Determining Model Fit. Electronic Journal of Business Research Methods. 2008;6(1):53-9. 34. Hu LT, Bentler PM. Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling. 1999;6(1):1-55. doi:10.1080/1070551990954011835. MacCallum RC, Browne MW, Sugawara HM. Power analysis and determination of sample size for covariance structure modeling. Psychological Methods. 1996;1(2):130-49. doi:10.1037/1082-989X.1.2.13036. Mundfrom DJ, Shaw DG, Tian Lu K. Minimum Sample Size Recommendations for Conducting Factor Analyses. International Journal of Testing. 2005;5(2):159-68. doi:10.1207/s15327574ijt0502_437. Costello AB, Osborne JW. Best practices in exploratory factor analysis: Four recommendations for getting the most from your analysis. Practical Assessment, Research and Evaluation. 2005;10(7). 38. Kline P. An easy guide to factor analysis. New York: Routledge; 1994.39. Gorsuch R. Factor Analysis. 2nd ed. Hillsdale, NJ: Erlbaum1983.40. Cohen J. Statistical power analysis for the behavioral sciences 2nd edition ed. Mahwah, NJ: Erlbaum; 1988.41. Little RJ, D'Agostino R, Cohen ML, et al. The prevention and treatment of missing data in clinical trials. The New England Journal of Medicine. 2012;367(14):1355-60. 42. Dziura JD, Post LA, Zhao Q, Fu Z, Peduzzi P. Strategies for dealing with missing data in clinical trials: from design to analysis. The Yale Journal Of Biology And Medicine. 2013;86(3):343-58. 43. Schafer JL, Graham JW. Missing data: Our view of the state of the art. Psychological Methods. 2002;7(2):147-77. doi:10.1037/1082-989X.7.2.14744. Hawkins DM. Identification of outliers. London: Chapman & Hall.1980.45. McCracken LM, Eccleston C, Vowles KE. Acceptance-based treatment for persons with complex, long standing chronic pain: A preliminary analysis of treatment outcome in comparison to a waiting phase. Behaviour Research and Therapy. 2005;43(10):1335-46. doi:10.1016/j.brat.2004.10.00346. Trompetter HR, ten Klooster PM, Schreurs KMG, Fledderus M, Westerhof GJ, Bohlmeijer ET. Measuring values and committed action with the Engaged Living Scale (ELS): Psychometric evaluation in a nonclinical sample and a chronic pain sample. Psychological Assessment. 2013;25(4):1235-46. doi:10.1037/a003381347. Baranoff J, Hanrahan S, Kapur D, Connor J. Validation of the Chronic Pain Acceptance Questionnaire-8 in an Australian Pain Clinic Sample. International Journal of Behavioral Medicine. 2014;21(1):177-85. doi:10.1007/s12529-012-9278-648. Bendayan R, Esteve R, Blanca MJ. New empirical evidence of the validity of the Chronic Pain Acceptance Questionnaire: The differential influence of activity engagement and pain willingness on adjustment to chronic pain. British Journal of Health Psychology. 2012;17(2):314-26. doi:10.1111/j.2044-8287.2011.02039.x49. Costa J, Pinto-Gouveia J. Acceptance of pain, self-compassion and psychopathology: Using the Chronic Pain Acceptance Questionnaire to identify patients' subgroups. Clinical Psychology & Psychotherapy. 2011;18(4):292-302. doi:10.1002/cpp.71850. Fish RA, McGuire B, Hogan M, Stewart I, Morrison TG. Validation of the Chronic Pain Acceptance Questionnaire (CPAQ) in an Internet sample and development and preliminary validation of the CPAQ-8. Pain. 2010;149(3):435-43. doi:10.1016/j.pain.2009.12.01651. Hayes SC, Bissett RT, Korn Z, et al. The Impact of Acceptance Versus Control Rationales on Pain Tolerance. Psychological Record. 1999;49(1):33-47. 52. McCracken LM. Learning to live with the pain: acceptance of pain predicts adjustment in persons with chronic pain. Pain. 1998;74(1):21-7.

25

53. Mesgarian F, Asghari A, Shaeiri MR, Broumand A. The Persian Version of the Chronic Pain Acceptance Questionnaire. Clinical Psychology & Psychotherapy. 2013;20(4):350-8. doi:10.1002/cpp.176954. Monticone M, Ferrante S, Rocca B, Nava T, Parini C, Cerri C. Chronic Pain Acceptance Questionnaire Confirmatory Factor Analysis, Reliability, and Validity in Italian Subjects With Chronic Low Back Pain. Spine. 2013;38(13):E824-E31. 55. Ning MC, Ming TWC, Mae JYC, Ping CP. Validation of the Chronic Pain Acceptance Questionnaire (CPAQ) in Cantonese-Speaking Chinese Patients. Journal of Pain. 2008;9(9):823-32. doi:10.1016/j.jpain.2008.04.00556. Vowles KE, McCracken LA, Eccleston C. Patient functioning and catastrophizing in chronic pain: The mediating effects of acceptance. HEALTH PSYCHOLOGY. 2008;27(2):S136-S43. 57. Vowles KE, McCracken LM. Acceptance and values-based action in chronic pain: A study of treatment effectiveness and process. Journal of Consulting and Clinical Psychology. 2008;76(3):397-407. doi:10.1037/0022-006X.76.3.39758. Vowles KE, McCracken LM, Eccleston C. Processes of change in treatment for chronic pain: The contributions of pain, acceptance, and catastrophizing. European Journal of Pain. 2007;11(7):779-87. doi:10.1016/j.ejpain.2006.12.00759. Vowles KE, McNeil DW, Gross RT, et al. Effects of pain acceptance and pain control strategies on physical impairment in individuals with chronic low back pain. Behavior Therapy. 2007;38(4):412-25. doi:10.1016/j.beth.2007.02.00160. Wright MA, Wren AA, Somers TJ, et al. Pain Acceptance, Hope, and Optimism: Relationships to Pain and Adjustment in Patients With Chronic Musculoskeletal Pain. The Journal of Pain. 12(11):1155-62. 61. McCracken LM, Keogh E. Acceptance, Mindfulness, and Values-Based Action May Counteract Fear and Avoidance of Emotions in Chronic Pain: An Analysis of Anxiety Sensitivity. Journal of Pain. 2009;10(4):408-15. doi:10.1016/j.jpain.2008.09.01562. Páez-Blarrina M, uciano C, Valdivia S, Gutiérrez-Martínez O, Ortega J, Rodríguez-Valverde M. The role of values with personal examples in altering the functions of pain: Comparison between acceptance-based and cognitive-control-based protocols. Behaviour Research and Therapy. 2008;46(1):84-97. doi:10.1016/j.brat.2007.10.00863. McCracken LM, Vowles KE. A Prospective Analysis of Acceptance of Pain and Values-Based Action in Patients With Chronic Pain. Health Psychology. 2008;27(2):215-20. doi:10.1037/0278-6133.27.2.21564. Trompetter HR, ten Klooster PM, chreurs KMG, Fledderus M, Westerhof GJ, Bohlmeijer ET. Measuring values and committed action with the Engaged Living Scale (ELS): Psychometric evaluation in a nonclinical sample and a chronic pain sample. Psychological Assessment. 2013;25(4):1235-46. doi:10.1037/a003381365. McCracken LM, Gauntlett-Gilbert J, Vowles KE. The role of mindfulness in a contextual cognitive-behavioral analysis of chronic pain-related suffering and disability. Pain. 2007;131(1-2):63-9. doi:10.1016/j.pain.2006.12.01366. McCracken LM, Gutiérrez-Martínez O, Smyth C. “Decentering” reflects psychological flexibility in people with chronic pain and correlates with their quality of functioning. Health Psychology. 2013;32(7):820-3. doi:10.1037/a002809367. Williams AC, Eccleston C, Morley S. Psychological therapies for the management of chronic pain (excluding headache) in adults. The Cochrane database of systematic reviews. 2012;11:CD007407. doi:10.1002/14651858.CD007407.pub368. Turner JA, Holtzman S, Mancl L. Mediators, moderators, and predictors of therapeutic change in cognitive-behavioral therapy for chronic pain. Pain. 2007;127(3):276-86. doi:10.1016/j.pain.2006.09.005

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