The Fear of Pain Questionnaire (FOPQ): Assessment of Pain-Related Fear Among Children and Adolescents With Chronic Pain

The Journal of Pain, Vol 12, No 6 (June), 2011: pp 677-686 Available online at www.sciencedirect.com

The Fear of Pain Questionnaire (FOPQ): Assessment of Pain-Related Fear Among Children and Adolescents With Chronic Pain Laura E. Simons,*,y Christine B. Sieberg,*,y Elizabeth Carpino,* Deirdre Logan,*,y and Charles Berde* * Division of Pain Medicine, Department of Anesthesiology, Perioperative and Pain Medicine, Children’s Hospital Boston, Waltham, Massachusetts. y Department of Psychiatry, Harvard Medical School, Boston, Massachusetts.

Abstract: An important construct in understanding pain-related disability is pain-related fear. Heightened pain-related fear may result in behavioral avoidance leading to disuse, disability, and depression; whereas confrontation of avoided activities may result in a reduction of fear over time and reengagement with activities of daily living. Although there are several measures to assess pain-related fear among adults with chronic pain, none exist for children and adolescents. The aim of the current study was to develop a new tool to assess avoidance and fear of pain with pediatric chronic pain patients: the Fear of Pain Questionnaire, child report (FOPQ-C), and Fear of Pain Questionnaire, parent proxy report (FOPQ-P). After initial pilot testing, the FOPQ-C and FOPQ-P were administered to 299 youth with chronic pain and their parents at an initial multidisciplinary pain treatment evaluation. The FOPQ demonstrated very strong internal consistency of .92 for the child and parent versions. One-month stability estimates were acceptable and suggested responsivity to change. For construct validity, the FOPQ correlated with generalized anxiety, pain catastrophizing, and somatization. Evidence of criterion-related validity was found with significant associations for the FOPQ with pain, healthcare utilization, and functional disability. These results support the FOPQ as a psychometrically sound measure. Perspective: Pain-related fear plays an important role in relation to emotional distress and painrelated disability among children and adolescents with chronic pain. Identification of patients with high levels of fear avoidance of pain with the FOPQ will inform how to proceed with psychological and physical therapy interventions for chronic pain. ª 2011 by the American Pain Society Key words: Chronic pain, pain-related fear, anxiety, child, assessment.

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hronic pain in children is a significant problem, affecting approximately 15 to 25% of children, with approximately 3% in need of intensive pain rehabilitation.14 The biopsychosocial model of chronic pain encompasses psychosocial processes that reciprocally

Received September 20, 2010; Revised November 5, 2010; Accepted December 14, 2010. Supported by the Children’s Hospital Boston Career Development Fellowship Award, the Sara Page Mayo Endowment for Pediatric Pain Research and Treatment, and the Department of Anesthesiology, Perioperative and Pain Medicine at Children’s Hospital Boston. There are no conflicts of interest to report. Address reprint requests to Laura E. Simons, PhD, Mayo Family Pediatric Pain Rehabilitation Center, Children’s Hospital Boston at Waltham, 9 Hope Avenue Waltham, MA 02453. E-mail: Laura.Simons@childrens. harvard.edu 1526-5900/$36.00 ª 2011 by the American Pain Society doi:10.1016/j.jpain.2010.12.008

interact with physiologic processes to influence pain outcomes such as pain perception and disability.31 One psychological process that has received significant support in predicting chronic pain and associated disability in the adult literature is pain-related fear.17,36 Pain-related fear emerges when stimuli that are related to pain are perceived as threatening. The FearAvoidance Model of Pain20 describes how pain-related fear impacts outcomes for individuals experiencing persistent pain. In this model, if the pain is interpreted as threatening, pain-related fear develops, leading to avoidance behaviors and hypervigilance. This is followed by disability, disuse, and depression. These adverse outcomes fuel the cycle of increased fear and avoidance. Alternately, absence of pain-related fear leads to rapid confrontation through continued engagement in routine daily activities and resultant recovery. 677

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Although assessing pain-related fear is extremely important, it is complex, as it may involve fear of reinjury, movement, physical activity, or a combination of these factors. In addition, patients often do not report or subjectively experience feeling fearful of pain’, but simply find it difficult to perform the movements or activities that are being asked of them.36 Several measures have been developed in the adult literature to assess pain-related fear: these include the Tampa Scale for Kinesiophobia (TSK), which assesses fear of reinjury due to movements28,35; the Pain Anxiety Symptoms Scale (PASS),6,26,27 which assesses fear of pain across cognitive, overt behavioral and physiological domains; the Fear-Avoidance Beliefs Questionnaire (FABQ),37 assessing beliefs about the impact of physical activity and work on pain; and, most recently, the Psychological Inflexibility in Pain Scale (PIPS).42 The PIPS measures specific avoidance behaviors and cognitive fusion—the process in which thoughts about an event become merged with the actual event, causing these thoughts to evoke the same emotional reaction as the event itself13—adding new dimensions to the understanding of pain-related fear. Taken together, pain-related fear has a well-demonstrated role in the adult chronic pain literature, yet this construct has received scant attention in the pediatric chronic pain literature. The aim of this study was to develop a child self-report and parent proxy report measure to assess pain-related fear in children and adolescents with chronic pain; the Fear of Pain Questionnaire, child and parent report (FOPQ-C; FOPQ-P). After pilot work to generate a refined item pool, expected subscales on the FOPQ included: 1) Fear of Pain; 2) Avoidance of Activities; 3) Cognitive Fusion; and 4) Somatic Fear. With regards to reliability, we hypothesized that the total scale and subscales of the FOPQ would be internally consistent. We also examined stability of scores 1 month following the pain clinic evaluation. We anticipated scores to be consistent across demographic variables. With regards to construct validity, we hypothesized that greater pain-related fear as measured by the FOPQ would be correlated with similar constructs of catastrophizing, generalized anxiety, and somatization. For criterion-related validity, we hypothesized that fear of pain would be associated with higher levels of pain severity, greater healthcare utilization, and pain-related functional disability.

Among the total sample, children and adolescents were predominantly Caucasian (93%) and female (80%), reflecting the composition of patients seen in this tertiary care clinic. The mean age was 13.8 years (SD = 2.4). Parents completing the questionnaires were predominantly mothers (91%). Race and age were not collected for the participating parent. Pain diagnoses assigned by the physician conducting the medical portion of the clinical evaluation included: musculoskeletal pain (eg, diffuse muscular, 1 or more joints, 30%); neuropathic pain (eg, complex regional pain syndrome [CRPS], 36%); headache (chronic daily, tension-type, migraine, 2%); back pain (15%); recurrent abdominal pain (8%); gynecological or genitourinary pain (5%); and other pain (eg, chest pain, 5%). Duration of pain varied greatly from 1 month to 206 months, with median duration of pain 14 months and 10% experiencing their current pain symptoms for less than 3 months prior to this clinic visit. The majority of parents in this sample were married (79%) and a large percentage well educated (ie, college graduate or higher: 61% for mothers, 59% for fathers). Family socioeconomic status (SES) based on the 4-factor index of social status28 ranged from 15 (laborer) to 66 (business owner; professional), with a mean of 46.1 (SD = 11.4).

Participants: 1-Month Stability

Methods

Among the 299 parents and children contacted 4 weeks after their initial evaluation at the pain clinic, 238 (80%) returned follow-up measures. Among the 61 who did not follow-up, reasons for nonparticipation included: failure to respond after repeated attempts to contact (n = 32); declined participation (n = 2); could not be reached (n = 14; phone disconnected, no voice mail); indicated they would return follow-up forms and did not (n = 13). No significant differences were found between families who completed follow-up interviews and those who did not on age, gender, parent marital status, SES, duration of pain, and pain level (current, lowest, highest, average) at the initial evaluation. Parent Fear of Pain Questionnaire scores were significantly lower for those who participated in the follow-up (M = 41.7, SD = 16.3) compared to those who did not (M = 47.8, SD = 16.0), F(1,294) = 6.82, P < .01. The Functional Disability Inventory was administered at the 4-week follow-up after initiation of the study based on a hypothesis derived during interim analysis, resulting in 151 of the 238 follow-up participants completing this measure at follow-up.

Participants

Materials

All patients 8 to 17 years of age who underwent a multidisciplinary pain evaluation at a tertiary pain clinic in a large, urban northeast pediatric hospital between September 2008 and May 2010 were eligible for the study. One parent of each child also participated. Of the 346 children and adolescents and parents approached to participate in this study, 299 consented and 296 completed a sufficient amount of data at initial evaluation for inclusion in these analyses, resulting in a 86% consent rate and 99% initial completion rate.

Initial Item Development: Pilot Version of the Fear of Pain Questionnaire (FOPQ) As no measure of this kind existed in the pediatric pain literature; items for the FOPQ were derived from clinical expertise, patient and family feedback, and 4 validated measures in the adult chronic pain literature specifically designed to measure fear of movement/pain. Items from these 4 measures were adapted for language appropriate for younger readers. In addition, we were interested

Simons et al in creating a child and parent version, with the parent version referring to parent perceptions of their child’s pain-related fear experience. The 4 validated measures from the adult pain literature included: the Tampa Scale for Kinesiophobia (TSK-11),28,35 the Psychological Inflexibility in Pain Scale (PIPS),42 the Pain Anxiety Symptom Scale (PASS-20),6,27 and the Fear Avoidance Beliefs Questionnaire (FABQ).37 Response formats for these 4 scales range from a 4-point to a 7-point Likert-type scale. Given that this is a pediatric sample, we limited the response format to a 5-point Likert-type scale, ranging from ‘‘strongly disagree’’ to ‘‘strongly agree.’’ This wording is consistent with 2 of the adult measures (TSK-11 and FABQ) and a response format commonly used in pediatric samples. Respondents were instructed: ‘‘With this questionnaire, we measure how you (your child) look at pain. Please read each statement carefully. Check the box to the right that reflects how much you agree or disagree with each statement. This is not a test of your medical knowledge and there are no good or bad answers. We are interested in your opinion, not that of other people.’’ Below are descriptions of each of the measures that made up the initial item pool.

Tampa Scale for Kinesiophobia (TSK-11) The TSK-1128,35 is an 11-item measure that assesses fear of movement and injury. This measure consists of 2 subscales; Somatic Focus and Activity Avoidance. This is a shortened version of the 17-item original.35

Psychological Inflexibility in Pain Scale (PIPS) The PIPS42 is a 16-item scale that assesses psychological inflexibility in individuals living with chronic pain. The measure consists of 2 subscales, Avoidance and Cognitive Fusion. The questionnaire has excellent internal consistencies; .89 for the total scale, .90 Avoidance, and .75 Cognitive Fusion.42

Pain Anxiety Symptom Scale (PASS-20) The PASS-206,27 is a 20-item measure that assesses 4 pain anxiety constructs that include fear of pain, cognitive anxiety, escape-avoidance behaviors, and physiological symptoms of anxiety. This is a shortened version of the 40-item original.27

Fear Avoidance Beliefs Questionnaire (FABQ) The FABQ37 consists of 2 subscales, FABQ-Physical Activities and FABQ-Work. The FABQ-Work items were modified to reflect school to be applicable to children and adolescents. It consists of 4 items. Higher scores represent greater levels of fear-avoidance beliefs.

Pilot Study Pilot data were collected to refine the items for the parent and child versions of the Fear of Pain Questionnaire (FOPQ). We collected qualitative and quantitative data. Patient families who are regularly followed at the Chronic Pain Clinic (CPC) and those who presented for an initial evaluation at the CPC were recruited for the pilot study. A parent and the patient presenting with pain

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reviewed the initial item pool to assess readability and understandability. Twenty children and their parent reviewed the item pool. Patient ages ranged from 8 to 17 years (M = 13.3, SD = 2.3). Pain diagnoses included: 25% neuropathic pain (eg, complex regional pain syndrome), 25% recurrent abdominal pain, 20% back/neck pain, 15% musculoskeletal pain, 10% gynecological or genitourinary pain, and 5% headache pain. Parental education level was assessed. Half of mothers reported having a college degree or beyond (50%), 25% indicated some education beyond high school, and 15% completed high school. The majority of fathers reported obtaining a college degree or more (62%), 11% indicated education beyond high school and 25% completed high school. In addition to recruitment of participant families, a panel of experts in pain treatment was also invited to review the item pool (including the authors of the 4 adult measures represented in the item pool). They quantitatively rated how representative each item was for the domain for which it was assigned on a 5-point Likert-type scale. The domains were: 1) Fear of Pain; 2) Avoidance of Activities; and 3) Cognitive Fusion. They were also asked to identify items which they believed were incongruent with their nominated domain and assign them to an alternative domain. If they did not believe that an item could be placed on an alternative domain, they indicated whether the item should be eliminated or a new domain created. Finally, the members of the expert panel examined the clarity of wording to ensure there were no ambiguous or poorly written items. We calculated interrater consistency (Lawshe’s Content Validity Ratio)16 to assist in shortening the item pool and to assess face and content validity. The expert panel consisted of 16 members including 11 psychologists, 3 physical therapists, and 2 physicians. Each panel member indicated a specialty in pain treatment. We calculated interrater consistency (CVR) from panel member responses with a .49 cut-off value necessary for item inclusion (CVR values range from 1.0 to 11.0). We describe below the process of refining items from the original item pool to the current item pools for each subscale.

Fear of Pain Questionnaire, Child Report Following pilot testing, the FOPQ-C consisted of 37 items. The original item pool consisted of 46 items. Based on the expert panel feedback and parent comments and feedback, 32 items were retained and 5 new items were added. The initial 3 hypothesized domains were modified and retained: Avoidance of Activities (15 items), Fear of Pain (9 items), and Cognitive Fusion (8 items). In addition, a new domain was created, labeled Somatic Fear (5 items). The average CVR rating for the FOPQchild report was .65 (SD = .04) and the clarity rating (percent of children who indicated the question made sense to them) was 89.5% (SD = 3.7%).

Fear of Pain Questionnaire, Parent Report After pilot testing, FOPQ-P consisted of 38 items. Of the 46 original items, 33 were retained and 5 were added based on expert panel and parent comments and feedback.

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The initial 3 domains were modified and retained: Avoidance of Activities (14 items), Fear of Pain (10 items), and Cognitive Fusion (9 items). Similar to the FOPQ-C, a new domain was created, labeled Somatic Fear (5 items). The average CVR rating for the FOPQ-P was .75 (SD = .06) and the clarity rating was 95.2% (SD = 2.4%).

FOPQ Validation Basic demographic (eg, age, gender) and medical information (eg, diagnosis assigned by the evaluating pain physician) was collected from patient charts.

Construct Validity Somatic Symptoms The Children’s Somatization Inventory (CSI)38 assesses the severity of nonspecific somatic symptoms (eg, ‘‘weakness,’’ ‘‘dizziness’’) that need not have organic disease etiology. Respondents rate the extent to which they have experienced each of 35 symptoms during the last 2 weeks using a 5-point scale ranging from ‘‘not at all’’ (0) to ‘‘a whole lot’’ (4). Higher scores indicate higher levels of somatic symptoms; total scores are computed by summing the items. The CSI has been found to have adequate reliability and validity.38

Anxiety Symptoms The Multidimensional Anxiety Scale for Children (MASC)23 is a 39-item, self-report inventory assessing 4 domains of anxiety in children: physical symptoms (eg, tension), harm avoidance (eg, perfectionism), social anxiety (eg, rejection), and separation anxiety. The factor structure of the MASC is stable across age and gender. Strong reliability and validity data exist for this measure.23

Functional Disability The Functional Disability Inventory (FDI)39 is a scale that assesses difficulty in physical and psychosocial functioning due to physical health. The instrument consists of 15 items concerning perceptions of activity limitations during the past 2 weeks; total scores are computed by summing the items. Higher scores indicate greater disability. The FDI has good reliability and validity.5 This measure was completed at baseline and again at 4 weeks by the child.

Procedure Participants were recruited during their multidisciplinary pain clinic appointment within a large children’s hospital. The study was approved by the hospital’s Institutional Review Board. Patients and their parents were approached by a research assistant during their evaluation and were asked to consent/assent both for this particular study and also if their responses to clinic measures could be used for research purposes. Four weeks after initial data collection, participant parents and children were contacted and mailed the FOPQparent and child form to assess measure stability. Preliminary interim analyses suggested variability in FOPQ scores from initial administration of the measure; therefore the Functional Disability Inventory was added to examine relations between changes in disability as it relates to changes in FOPQ scores.

Statistical Analyses

Criterion-Related Validity

Data was entered into SPSS v.18.0 (SPSS Inc, Chicago, IL). Descriptive statistics were conducted to examine underlying assumptions of normality for all variables of interest. To refine the items on the FOPQ measures, significant skewing or kurtotic response patterns were examined. Item-total correlations were calculated for both measures. Maximum likelihood factor analyses with oblique rotation were conducted for both measures to further refine the items and establish subscales for both measures.7 Consistency across demographic variables and validity of the FOPQ was examined with bivariate correlations and 1-way ANOVAs. Measure stability was examined 4 weeks after initially completing the FOPQ using paired-sample t-tests, and change scores were calculated for the FOPQ and FDI to examine treatment responsivity.

Pain

Results

During the pain evaluation, children were asked to provide their average pain rating on a standard 11-point numeric rating scale32 from 0 (no pain) to 10 (most pain possible).

Item Selection and Factor Analysis: FOPQ Validation

Pain Catastrophizing The Pain Catastrophizing Scale (PCS-C, PCS-P)8,12 assesses negative thinking associated with pain. It is comprised of 13 items rated on a 5-point scale. Items are summed to derive a total score. Higher scores indicated higher levels of catastrophic thinking. Internal consistency of the Total Score on this measure is .90.8

Healthcare Utilization To assess healthcare utilization, parents reported number of physician visits and emergency room visits in the 3 months prior to the pain clinic evaluation. Testretest reliability for these questions have been found to be acceptable, .76 physician visits, .94 emergency room visits.22

Children with chronic pain and their parents enrolled in the current study completed the refined FOPQ. For both measures, each item was examined to determine its contribution to the scale. Significant skew and/or kurtosis were examined, item-total correlations were conducted, and lastly, all remaining items were entered into a maximum likelihood factor analysis with oblique rotation to generate the most parsimonious measure of pain-related fear.

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Child Scale Item Selection and Factor Analysis Each of the 37 items retained from the pilot study was examined to determine its contribution to the scale. No items violated assumptions of normality (skew and/or kurtosis >2.0) Next, item-total correlations were conducted, with 2 items dropped (r < .30; criteria outlined by DeVellis9). The remaining items were entered into a maximum likelihood factor analysis with oblique rotation. The criteria of eigenvalues >1 resulted in an initial 8-factor solution that failed to converge. After examining the factor structure suggested by Cattell’s elbow criteria on the scree plot9 (2 factors), the hypothesized factor structure (4 factors), and factor structures above and below these parameters, a 2-factor solution best explained the structure of the FOPQ-C with 45% of the variance accounted for. Altogether, 11 items were dropped (7 had item loadings less than .32, 3 did not conceptually fit with the derived factors, and 1 loaded above .32 across both factors. The final 24-item scale had a Cronbach’s alpha of .92. Sample mean for the scale was 43.3 (SD = 18.0). FOPQ-C total scores were normally distributed across the sample. The results are consistent with the hypothesized subscales, with revision (see Table 1). Factor 1, labeled Fear of Pain, contains 13 items (a = .89). Sample mean for the subscale was 24.1 (SD = 10.7). This factor is consistent with the hypothesized Fear of Pain subscale with items hypothesized for the Somatic Fear subscale also on this dimension. Factor 2, labeled Avoidance of Activities, contains 11 items (a = .86). Sample mean for the subscale was 19.1 (SD = 9.1). This factor is consistent with the hypothTable 1.

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esized Avoidance of Activities subscale with items from the hypothesized Cognitive Fusion subscale also on this dimension. The 2 factors were intercorrelated (see Table 2).

Parent Scale Item Selection and Factor Analysis Each of the 38 items retained from the pilot study was examined to determine its contribution to the scale. No items violated assumptions of normality (skew and/or kurtosis >2.0) Next, item-total correlations were conducted, with 3 items dropped (r < .30; criteria outlined by DeVellis9). The remaining items were entered into a maximum likelihood factor analysis with oblique rotation. The criteria of eigen values >1 resulted in an initial 7-factor solution. Taking into account Cattell’s elbow criteria on the scree plot9 (2 factors), the number of hypothesized dimensions (4 factors), and visual inspection, a 3-factor solution best explained the structure of the FOPQ-P, with 12 items dropped that either did not conceptually fit with derived factors (1), loaded across factors (1), or had factor loadings less than .32 across domains (10). The 23-item scale had a Cronbach’s alpha of .92. Sample mean for the scale was 43.4 (SD = 16.4). FOPQ-P total scores were normally distributed across the parent sample. The results are consistent with the hypothesized subscales, with revision (see Table 3). Factor 1, labeled Avoidance of Activities, contains 10 items (a = .86). Sample mean for the subscale was 22.8 (SD = 8.6). Factor 2, labeled School Avoidance, contains 5 items (a = .80).

Summary of Factor Loadings for FOPQ-C ITEM

When I feel pain, I am afraid that something terrible will happen. I worry when I am in pain. Feelings of pain are scary for me. I find it difficult to calm my body down when having pain. I think that if my pain gets too bad, it will never get better. When I hurt I can’t stop thinking about the pain.* Pain causes my heart to beat fast or race. I’m afraid that when the pain starts, it’s going to be really bad. I walk around in constant fear of hurting.* I begin shaking/trembling when doing an activity that increases pain.* I can’t think straight when I feel pain.* When I sense pain, I feel dizzy or light-headed.* I can’t do all the things normal people do because it’s so easy to hurt my body. I put things off because of my pain.* I avoid making plans because of my pain. I cancel plans when I am in pain. I do not go to school because it makes my pain worse. I cannot go back to school until my pain is treated. I choose to miss things that are important to me so that I won’t feel my pain.* I go immediately to lie down or rest when I feel really bad pain.* I stop any activity if I start to hurt or my pain becomes worse.* When I am in pain, I stay away from other people. My pain controls my life. I do not think that I will ever be able to go back to a normal school schedule.* Eigenvalue % Variance *Designated items are unique to the child scale.

FEAR

AVOIDANCE

.83 .75 .69 .68 .67 .66 .58 .54 .53 .50 .45 .39 .34

8.64 35.98

.82 .80 .72 .61 .59 .56 .45 .40 .40 .39 .37 2.04 8.50

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Table 2.

Intercorrelations, Means, and Standard Deviations for FOPQ-Child

VARIABLE FOPQ-child 1. Total score 2. Fear of pain 3. Avoidance of activities Construct validity 4. Somatic symptoms 5. Anxiety symptoms 6. Catastrophizing Criterion-related validity 7. Pain ratings (average) 8. Functional disability 9. Doctor visits 10. Emergency room visits

1

2

3

4

5

6

7

8

9

10

M

SD

—

.92y —

.89y .65y —

.52y .51y .44y

.54y .57y .40y

.70y .73y .52y

.24y .21y .23y

.44y .34y .46y

.18y .15* .18y

.11 .10 .10

42.82 23.89 18.93

17.88 10.67 9.02

—

.41y —

.35y .44y —

.19y .03 .31y

.51y .21y .29y

.20y .14* .15*

.13* .14* .13*

30.35 48.95 40.31

17.55 12.73 11.27

—

.28y —

.12* .18* —

.05 .09 .28* —

6.00 23.64 4.61 .85

2.12 11.87 4.42 2.64

*P < .05. yP < .01; correlations are 2-tailed.

Sample mean for the subscale was 5.2 (SD = 4.3). Factor 3, labeled Fear of Pain, contains 8 items (a = .85). Sample mean for the subscale was 15.5 (SD = 6.3). Similar to the FOPQ-C, hypothesized items for the Cognitive Fusion subscale merged with the Avoidance of Activities subscale; whereas items related to school emerged as a separate construct dissimilar to the FOPQ-C. Also in line with the FOPQ-C, Somatic Fear items loaded on the Fear of Pain subscale. All 3 factors were intercorrelated (see Table 4) with 50.8% of the variance accounted for across the 3 scales. The child and parent-proxy versions of the FOPQ were significantly correlated (Total r = .54, Fear r = .51, Table 3.

Avoidance r = .47). Following item selection and factor analyses, we examined construct and criterion validity for the FOPQ total score and subscale scores.

FOPQ and Demographic Factors One-way ANOVAs were conducted to examine difference in FOPQ Total and subscale scores across categorical demographic factors, pain duration, and pain diagnosis. Given the preponderance of Caucasian participants (93%) we did not examine race or ethnicity. As was expected, no significant differences were detected across child gender, pain duration, or pain diagnosis. On the FOPQ-P, 2 significant differences emerged for parental

Summary of Factor Loadings for FOPQ-P ITEM

My child tries to avoid activities that cause pain.* My child avoids making plans because of his/her pain. My child is afraid that s/he might hurt him/herself if she exercises.* My child’s world has become small because of the pain.* My child thinks being careful to not make unnecessary movements is the safest thing s/he can do to stop the pain from worsening.* My child can’t do all the things normal people do because it is so easy to hurt his/her body. My child cancels plans when s/he is in pain. My child believes pain controls his/her life. My child says ‘‘I don’t have much energy’’, ‘‘I just can’t’’, ‘‘I have too much pain’’, or ‘‘I don’t feel like it’’.* When my child is in pain, s/he stays away from other people. My child does not go to school because s/he thinks it makes the pain worse. My child thinks that being at school makes the pain worse.* My child believes s/he cannot go back to school until his/her pain is treated. My child thinks that doing his/her schoolwork increases his/her pain.* My child thinks s/he should not do his/her schoolwork with his/her present pain.* My child worries when s/he is in pain. My child’s feelings of pain are scary to him/her. When my child is in pain, s/he is afraid something terrible will happen. When pain comes on strong my child thinks s/he might become injured or more disabled.* My child thinks that if the pain gets too bad, it will never get better. Pain seems to cause my child’s heart to pound or race. My child is afraid that when the pain starts, it’s going to be really bad. My child finds it difficult to calm his/her body down when in pain. Eigenvalue % Variance *Designated items are unique to the parent scale.

AVOIDANCE

SCHOOL

FEAR

.66 .65 .63 .61 .60 .60 .53 .52 .48 .47 .91 .66 .65 .42 .41

8.23 35.79

1.85 8.02

.87 .73 .70 .54 .50 .49 .41 .34 1.60 6.97

Simons et al Table 4.

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Intercorrelations, Means, and Standard Deviations for FOPQ-Parent

VARIABLE FOPQ-child 1. Total score 2. Fear of pain 3. Avoidance of activities 4. School avoidance Construct validity 5. Somatic symptoms 6. Anxiety symptoms 7. Catastrophizing Criterion-related validity 8. Pain ratings (average) 9. Functional disability 10. Doctor visits 11. Emergency room visits

1

2

3

4

5

6

7

8

9

10

11

M

SD

—

.86y —

.91y .63y —

.73y .52y .50y —

.45y .38y .37y .40y

.38y .38y .29y .28y

.41y .42y .34y .26y

.23y .18y .20y .22y

.46y .35y .44y .35y

.24y .21y .21y .19y

.17y .18y .10 .20y

42.97 15.38 22.43 5.16

16.40 6.32 8.73 4.26

—

.41y —

.35y .44y —

.19y .03 .31y

.51y .21y .29y

.20y .14* .15*

.13* .14* .13*

30.35 48.95 40.31

17.55 12.73 11.27

—

.28y —

.12* .18y —

.05 .09 .28y —

6.00 23.64 4.61 .85

2.12 11.87 4.42 2.64

*P < .05. yP < .01; correlations are 2-tailed.

marital status. Single parents (M = 47.47, SD = 15.79) reported higher levels of total fear of pain compared to married parents (M = 42.09, SD = 16.25), F(1,289) = 5.09, P < .05. Single parents (M = 6.21, SD = 4.61) also reported greater school avoidance scores compared to married parents (M = 4.92, SD = 5.18), F(1,289) = 4.29, P < .05. Older age was associated with the FOPQ-C Avoidance subscale and the FOPQ-P School Avoidance subscale. SES was negatively associated with the Total FOPQ-C scale, the FOPQ-C Avoidance subscale and Total FOPQ-P scale, indicating that lower SES is related to greater total fear of pain from the child and parent perspective and pain-related activity avoidance from the child perspective.

FOPQ Construct Validity Relations between the FOPQ and somatic symptoms, anxiety symptoms, and catastrophizing are displayed in Table 2 (FOPQ-C) and Table 4 (FOPQ-P). All variables were positively associated with higher levels of painrelated fear for the FOPQ Total scale and subscale scores. In relation to subscales, more frequent and severe somatic symptoms was most highly correlated with the FOPQ-C Fear subscale (r = .51) and FOPQ-P School subscale (r = .40). Anxiety symptoms were most highly correlated with the FOPQ Fear subscale (Child r = .57; Parent r = .38). Lastly, large magnitude correlations were detected in relation to pain catastrophizing with the largest found for the FOPQ Fear subscale (Child r = .73; Parent r = .42).

FOPQ Criterion-Related Validity Results for Pearson Product Moment correlation analyses between the FOPQ and pain ratings, functional disability, number of doctor visits in the previous 3 months, and number of emergency room visits in the previous 3 months are displayed in Table 2 (FOPQ-C) and Table 4 (FOPQ-P). Although the magnitude of correlations were similar across subscales in relation to pain ratings and number of doctor visits, functional disability was most highly correlated with the FOPQ Avoidance sub-

scale (Child r = .46; Parent r = .44). Frequency of emergency room visits in the previous 3 months was not significantly associated with FOPQ-C Total or subscale scores, but was associated with the FOPQ-P Fear and School Avoidance subscales.

FOPQ Stability To examine stability over time, parents and children completed the FOPQ 1 month later. Of the 299 participants enrolled, 80% completed the FOPQ at follow-up. Paired sample T-tests were conducted to examine stability in scores from evaluation to 1-month follow-up and are detailed in Table 5. There was a significant decrease in FOPQ scores from evaluation to 1-month follow-up across the total scale scores and subscales, except for the FOPQ-P School Avoidance subscale. Correlations across time ranged from .65 to .74. To evaluate if some patients experienced improvements in their symptoms and disability concomitant with an improvement or change in pain-related fear, we began administering the Functional Disability Inventory with the FOPQ at follow-up (n = 150) to explore this relationship. Decreases in functional disability were observed (see Table 5) and were significantly associated with concomitant decreases in FOPQ-C (r = .45, P < .00) and in the FOPQ-P (r = .30, P < .00) total scores, supporting our hypothesis.

Discussion The Fear of Pain Questionnaire developed in this study is a psychometrically promising measure to assess painrelated fear in children and adolescents. The scales were designed to be multidimensional, emphasizing the domains that contribute to fear avoidance of pain. After extensive pilot work, involving expert panel and parent and child feedback to generate a refined item pool, the items were administered to a large sample of youth with chronic pain and their parents. Using maximum likelihood factor analytic techniques, the following factors emerged for both measures: Fear of Pain and Avoidance of Activities. Uniquely, the parent measure

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Table 5.

One-Month Stability Estimates CLINIC EVALUATION SCALE

FOPQ-child Total scale Fear of pain Avoidance of activities FOPQ-parent Total scale Fear of pain Avoidance of activities School avoidance Functional disability inventory

ONE MONTH FOLLOW-UP

M

SD

M

SD

R

T

42.28 23.43 18.85

17.45 10.49 8.95

39.35 22.38 16.97

18.77 11.02 9.43

.74 .72 .73

3.38y 1.99* 4.26y

41.83 14.82 22.16 4.85 24.32

16.31 6.28 8.87 4.06 12.64

38.63 14.11 19.65 4.86 20.51

16.48 6.61 8.65 4.19 12.59

.70 .65 .65 .70 .65

3.84y 1.99* 5.20y .04 4.46y

*P < .05. yP < .01; correlations are 2-tailed.

had 1 additional subscale, School Avoidance, whereas this construct was represented within the Avoidance of Activities subscale for the child version. While 2 of our hypothesized subscales, Fear of Pain and Avoidance of Activities emerged as expected, Cognitive Fusion and Somatic Fears did not. Through refinement of the measure, many of the items that made up the Cognitive Fusion subscale were dropped, suggesting it is a separate entity from pain-related fear and may be more appropriately measured using a separate questionnaire. As for the Somatic Fear items, their placement on the Fear of Pain subscale seems fitting to encompass the cognitive and physiological aspects of pain-related fear whereas the Avoidance of Activities subscale emphasizes the behavioral aspects of pain-related fear. The partition of School Avoidance on the parent measure likely highlights the importance that parents place on school, separate from the many activities avoided in association with painrelated fear. Of note, despite the fact that many of the items proposed for the FOPQ were derived from previously validated measures of pain-related fear among adults, several items were eliminated during measure refinement. This suggests that many of those items may not be applicable among children and adolescents with chronic pain; evidence that developing measures for children and adolescents cannot simply consist of a downward extension of adult measures. Internal consistencies for both the FOPQ-C and FOPQ-P across total and subscale scores are strong. Scores on the FOPQ were consistent across gender, pain duration, and diagnosis. Older age was associated with greater activity avoidance per child report and greater school avoidance per parent report, suggesting that older adolescents are more likely to score higher on those domains and should be considered when using this tool to screen for elevated pain-related fears. In addition, the association between elevated FOPQ scores from the child and parent perspective and lower socioeconomic standing may indicate higher levels of pain-related fear among economically disadvantaged youth, although further inquiry is needed to understand this relationship. Lastly, single parents reported greater pain-related fears in their children as compared to married parents. It is unclear what factors

may be influencing these relations and replication of these findings is needed to substantiate the links between demographic factors and FOPQ scores. When examining the stability of the FOPQ over 1 month, virtually all scores significantly decreased at follow-up with concomitant decreases in functional disability, with the exception of school avoidance on the FOPQ-parent scale. This finding not only explains moderate measure stability, it also suggests decreases in painrelated fear may be associated with improvements in function. These preliminary findings suggest the FOPQ may be responsive to change in relation to treatment as all clinic patients are given specific treatment recommendations on evaluation day, although interim history of treatment seeking is not available to corroborate this hypothesis. While fearful attitudes toward pain appear to attenuate in a short window of time (4 weeks), the lack of change in school avoidance scores may reflect beliefs that require more time or direct intervention to result in change. These findings are essential to explore in future studies. The results provide initial support for the construct validity of the FOPQ with significant associations between pain-related fear and somatic symptoms, anxiety symptoms, and catastrophizing. Additionally, the results suggest evidence of criterion-related validity of the FOPQ with significant relations between pain-related fear and pain ratings, functional disability, and healthcare utilization. Additionally at the subscale level, the strong relations between general anxiety symptoms and somatic symptoms and the Fear of Pain subscale of the FOPQ in contrast to the strong association between the Avoidance of Activities subscale of the FOPQ and functional disability suggests discriminant validity among FOPQ dimensions. Of note, we found high correlations between catastrophizing and FOPQ scores. Recent research has emphasized the close link between catastrophizing and pain avoidance.30 Specifically, Tsao et al30 found that anxiety sensitivity, catastrophizing, and pain-related fears are highly similar but separate constructs, which could have implications for treating pain avoidance in children. As recent research has validated the measurement of anxiety sensitivity among children,1,24 including this construct to

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understand precursors to pain-related fear is essential. Further validation of this measure warrants inclusion of this variable of interest. There are also limitations to the current study. Using maximum likelihood factor analyses, initial 8- and 7- factor solutions emerged for the child and parent measures and were refined to 2 and 3 subscale measures, respectively. Although these solutions best fit the data, it is possible that other solutions could be derived with other samples, as observed with adult measures of pain-related fear (eg, TSK). The sample consisted primarily of Caucasian, female adolescents, which limits the generalizability of findings to males and diverse ethnic groups; however, this demographic pattern is commensurate with other pediatric multidisciplinary chronic pain clinic samples.4,10 Future research should focus on whether fear of pain varies as a function of race, ethnicity, and gender. Additionally, mostly mothers completed the parent measure. Fathers’ perspectives as they relate to child pain-related fear is also important to consider, particularly given recent findings that demonstrate differences in catastrophizing between mothers and fathers.15 There was also a lack of headache patients in this sample, as those patients are treated in another subprogram on a different campus (Pediatric Headache Program). As very little research exists even within the adult literature that has examined the role of pain-related fear among headache patients,25 this is an important area for future inquiry. There are important implications for this research. The literature among adults suggests that reducing elevated pain-related fear promotes participation in daily activities.3,18,21,43 When patients experience how returning to previously enjoyed activities does not lead to

catastrophic consequences, their misinterpretations are challenged and disconfirmed and they correct their fear expectancies.11,19,29 Graded in vivo exposure, developed by Vlaeyen et al,33,34 targets fear of pain and disability by deliberately exposing patients to movements and tasks previously avoided due to fear of pain or reinjury. A recent review among adult pain patients supports this intervention as more effective than wait-list controls in improving disability and reducing pain-related fear.2 Additionally, 2 published treatment studies targeting pain-related fear among adolescents echo these promising findings.40,41 These parent-and-child-completed measures now provide the opportunity to adequately assess and target painrelated fear among youth with chronic pain. In summary, this study not only provides a means of assessing a thus far neglected construct among children and adolescents with chronic pain, the results demonstrate that painrelated fear is associated with increased functional disability and other adverse psychological outcomes.

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