Research Report
Development of a Self-Report
Measure of Fearful Activities for
Patients With Low Back Pain: The Fear
of Daily Activities Questionnaire
Steven Z. George, Carolina Valencia, Giorgio Zeppieri Jr, Michael E. Robinson
Background. Self-report measures for assessing specific fear of activities have not
been reported in the peer-reviewed literature, but are necessary to adequately test
treatment hypotheses related to fear-avoidance models.
Objective. This study described psychomotor properties of a novel self-report
measure, the Fear of Daily Activities Questionnaire (FDAQ).
Design. A prospective cohort design was used.
Methods. Reliability and validity cohorts were recruited from outpatient physical
therapy clinics. Analyses for the reliability cohort included internal consistency and
48-hour test-retest coefficients, as well as standard error of measurement and minimal
detectable change estimates. Analyses for the validity cohort included factor analysis
for construct validity and correlation and multiple regression analyses for concurrent
and predictive validity. Four-week responsiveness was assessed by paired t test, effect
size calculation, and percentage of patients meeting or achieving MDC criterion.
Results. The FDAQ demonstrated adequate internal consistency (Cronbach
alpha⫽.91, 95% confidence interval⫽.87–.95) and 48-hour test-retest properties
(intraclass correlation coefficient⫽.90, 95% confidence interval⫽.82–.94). The standard error of measurement for the FDAQ was 6.6, resulting in a minimal detectable
change of 12.9. Factor analysis suggested a 2- or 3-factor solution consisting of loaded
spine, postural, and spinal movement factors. The FDAQ demonstrated concurrent
validity by contributing variance to disability (baseline and 4 weeks) and physical
impairment (baseline) scores. In predictive validity analyses, baseline FDAQ scores
did not contribute variance to 4-week disability and physical impairment scores, but
changes in FDAQ scores were associated with changes in disability. The FDAQ scores
significantly decreased over a 4-week treatment period, with an effect size of .86 and
55% of participants meeting the minimal detectable change criterion.
S.Z. George, PT, PhD, is Associate
Professor, Department of Physical
Therapy, Center for Pain Research
and Behavioral Health, Brooks
Center for Rehabilitation Studies,
University of Florida, PO Box
100154, Gainesville, FL 32615
(USA). Address all correspondence
to Dr George at: szgeorge@phhp.
ufl.edu.
C. Valencia, BS, is a student in the
Rehabilitation Science Doctoral
Program, Department of Physical
Therapy, University of Florida.
G. Zeppieri Jr, PT, MPT, is Staff
Physical Therapist, Shands Rehab
Center, UF Orthopaedics and
Sports Medicine Institute, Gainesville, Florida.
M.E. Robinson, PhD, is Professor,
Department of Clinical and Health
Physiology and Center for Pain Research and Behavioral Health, University of Florida.
[George SZ, Valencia C, Zeppieri
G Jr, Robinson ME. Development
of a self-report measure of fearful
activities for patients with low
back pain: the Fear of Daily Activities Questionnaire. Phys Ther.
2009;89:969 –979.]
© 2009 American Physical Therapy
Association
Limitations. The validity cohort was a secondary analysis of a clinical trial, and
additional research is needed to confirm these findings in other samples.
Conclusions. The FDAQ is a potentially viable measure for fear of specific
activities in physical therapy settings. These analyses suggest the FDAQ may be
appropriate for determining graded exposure treatment plans and monitoring
changes in fear levels, but is not appropriate as a screening tool.
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Self-Report Measure of Fearful Activities for Patients With LBP
T
he fear-avoidance model of
musculoskeletal pain (FAM) is
a current model used to explain the development and maintenance of chronic low back pain
(LBP).1 The FAM proposes that pain
perception is primarily influenced
by pain-related fear and pain catastrophizing.1–3 These psychological factors interact to determine an individual’s initial behavioral response to
acute pain. Low levels of pain-related
fear and pain catastrophizing are associated with a confrontation behavioral response, which is believed to
be a precursor to resuming normal
activities.1–3 In contrast, high levels
of pain-related fear and pain catastrophizing are associated with an
avoidance behavioral response,
which is believed to be a precursor
to experiencing chronic disability.1–3
Evidence supporting the FAM can be
found in prospective clinical studies
of pain-related fear. Several longitudinal studies4 –9 suggested that elevated measures of pain-related fear
were predictive of poor LBP outcomes. Evidence supporting the
FAM also can be found in studies
incorporating treatment strategies to
reduce pain-related fear. Effective
LBP treatment strategies consistent
with the FAM have been reported in
the literature, and these interventions include patient education,10,11
graded exercise,12,13 and graded exposure.14 –17 Collectively, the previously cited studies provide an empir-
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970
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ical foundation for the FAM and
suggest that the model may have
clinical relevance for patients with
LBP.1
Whether measurement of painrelated fear needs to be general or
specific to an activity is an unresolved issue related to the FAM.1 Validated questionnaires assess beliefs
related to the perceived harm and
threat of experiencing LBP or performing physical activity while in
pain.18,19 Examples of specific activities are not provided when patients
respond to these questionnaires,18,19
limiting their use in developing treatment programs that incorporate
graded, hierarchical exposure to specific fearful activities (ie, graded exposure). It has been hypothesized
that graded exposure is more effective than quota-driven approaches to
increasing general activity levels (ie,
graded activity or exercise).1,14,20,21
Measurement limitations may hamper future clinical investigation of
the FAM because testing graded exposure hypotheses in physical therapy settings require reliable and valid
instruments to assess fear of specific
activities.
Therefore, the purpose of this study
was to describe the psychometric
properties of a novel self-report measure for fear of activities for patients
with LBP. The Fear of Daily Activities
Questionnaire (FDAQ) recently was
developed to guide physical therapy
supplemented with graded exposure
in a clinical trial.20 In the current
study, we investigated test-retest reliability, internal consistency, construct validity, concurrent validity,
predictive validity, and responsiveness for the FDAQ. We hypothesized
that the FDAQ would demonstrate
adequate psychometric properties,
suggesting potential utility for patients with LBP.
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Method
Overview
All participants provided informed
consent before study participation
was confirmed. Psychometric properties of the FDAQ have not been
reported previously, and 2 cohorts
were recruited for this study. The
first cohort consisted of patients
with chronic LBP. These participants
were used primarily for analyses to
investigate the reliability of FDAQ
scores because they would be clinically stable during the 48-hour testretest period. The second cohort
consisted of participants with acute
or subacute LBP participating in a
clinical trial.20 These participants
were expected to have changes in
their clinical status during the
4-week follow-up and were used in
analyses to investigate the validity of
FDAQ scores. The clinical trial utilized the FDAQ to measure specific
fear of activities for implementing
graded exposure, but the FDAQ was
not used as an outcome measure.
Participants
The inclusion and exclusion criteria
for the reliability and validity cohorts
were based on guidelines from the
Quebec Task Force on Spinal Disorders.22 For the purposes of this
study, acute and subacute LBP were
operationally defined as reporting
current symptoms for 1 to 24 weeks
and chronic LBP was defined as reporting current symptoms for
greater than 24 weeks.
Reliability cohort. A sample of
convenience was recruited from patients seeking treatment for LBP at
University of Florida–affiliated outpatient clinics. Inclusion criteria were
being between 15 and 60 years of
age and having chronic LBP with or
without radiating symptoms. Patients had to have the ability to read
and speak English because questionnaires were used. Exclusion criteria
were having acute or subacute LBP,
signs of nerve root compression,
September 2009
Self-Report Measure of Fearful Activities for Patients With LBP
lumbar spinal stenosis, or postoperative lumbar spine surgery. Patients
also were excluded for pregnancy,
osteoporosis, and spinal disorders related to metastatic disease, visceral
disease, or fracture.
tings, and providing patients with
options for open-ended responses.
This modified version of the FDAQ
was used in the previously described
cohorts for formal psychometric
analyses.
item scale that assesses the degree of
catastrophic cognitions a patient reports due to LBP. The PCS has a total
range of scores of 0 to 52, and higher
scores are associated with higher
amounts of pain catastrophizing.
Validity cohort. Consecutive patients seeking treatment for LBP at
University of Florida–affiliated clinics
were recruited. Inclusion criteria
were being between 15 and 60 years
of age and having acute or subacute
LBP with or without radiating symptoms. Patients had to have the ability
to read and speak English because
questionnaires were used. Exclusion
criteria were having chronic LBP,
signs of nerve root compression,
lumbar spinal stenosis, or postoperative lumbar spine surgery. Patients
also were excluded for pregnancy,
osteoporosis, and spinal disorders related to metastatic disease, visceral
disease, or fracture.
The FDAQ lists 10 activities that patients with LBP commonly report as
being fearful of performing due to
LBP (Appendix). The FDAQ has 2
options for open-ended responses so
that patients with LBP can provide
additional examples and ratings of
activities that they fear performing
due to pain. Patients rate each FDAQ
item using a numerical rating scale
(NRS) ranging from 0 (“no fear”) to
100 (“maximal fear”). The FDAQ is
scored by totaling the NRS ratings for
the 10 standard activities and dividing by 10. Higher FDAQ scores indicate higher fear of activities. The
open-ended responses were not included in the current analyses because responses varied in the appropriateness for rehabilitation, were
not always associated with the highest fear ratings, and were not always
provided by the participants. These
issues made incorporation of the
open-ended responses difficult for
ranking and scoring purposes.
Therefore, the decision was made to
exclude the open-ended responses
from these analyses, but we still believe they are potentially useful for
clinical decision-making purposes.
Physical impairment. The previously described Physical Impairment
Scale (PIS)23 was used to quantify
physical impairment due to LBP. The
PIS consists of 7 different examination procedures performed by the
patient, and performance for each
procedure is scored as a negative (0)
or positive (1) for presence of impairment. The PIS has a total range of
scores of 0 to 7, and higher scores
indicate higher levels of physical impairment due to LBP.
Measures
FDAQ. The FDAQ was developed
by a group of health care professionals involved in rehabilitation of
chronic musculoskeletal pain from
clinics in Gainesville, Florida, and
Jacksonville, Florida. The group’s
goal was to create a self-report measure that is easy to administer, appropriate for use in determining graded
exposure activity prescription, and
acceptable for tracking changes in
fear of activities. A physician, 2 physical therapists, and 2 psychologists
generated potential items for the
FDAQ over 2 separate meetings. A
preliminary form of the FDAQ was
created and pilot tested in the Jacksonville clinic for 6 months. The
FDAQ then was further modified
based on input from psychologists,
physical therapists, and patients, as
well as preliminary analyses. Modifications to the FDAQ included shortening of the total number of items,
eliminating redundant items, removing items that could not be incorporated in standard rehabilitation setSeptember 2009
Previously validated measures
consistent with the FAM. The
Fear-Avoidance Beliefs Questionnaire (FABQ) was used to quantify
fear-avoidance beliefs.19 The FABQ
contains 2 scales: a 7-item FABQ
work scale (FABQ-W, range of
scores⫽0 – 42) and a 4-item FABQ
physical activity scale (FABQ-PA,
range of scores⫽0 –24). Higher
scores indicate higher levels of fearavoidance beliefs for both FABQ
scales. The Pain Catastrophizing
Scale (PCS) was used to quantify pain
catastrophizing.18 The PCS is a 13-
Pain and disability. Participants
rated their pain intensity using an
NRS ranging from 0 (“no pain”) to 10
(“worst pain imaginable”).24 They
rated pain intensity over 3 conditions: the present pain intensity, the
worst pain intensity over the past 24
hours, and the best pain intensity
over the past 24 hours. These 3 ratings were summed and divided by 3
(arithmetic mean) for use in data
analyses.25 Disability was assessed
with the Oswestry Disability Questionnaire (ODQ), which has been
recommended as an appropriate outcome measure for self-report of disability.26,27 The ODQ has 10 items
that assess how LBP affects common
daily activities (eg, sitting, standing,
lifting). The ODQ has a range of
scores of 0 (“no disability due to
back pain”) to 100 (“completely disabled due to back pain”), so higher
scores indicate higher disability from
LBP.
Procedure
Reliability
cohort. Participants
who met the eligibility criteria for
the reliability cohort provided informed consent and completed the
FDAQ, NRS for pain intensity, and
ODQ during a routine appointment
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for outpatient physical therapy. They
then were given a self-addressed,
stamped envelope with instructions
to complete the FDAQ again 48
hours later. They were instructed to
complete the FDAQ, provide the
date of completion on the form, and
mail it to the authors.
Validity cohort. Participants who
met the eligibility criteria for the validity cohort provided informed consent and completed the FDAQ, along
with the FABQ, PCS, NRS for pain
intensity, and ODQ. A physical therapist who was masked to group assignment administered the PIS at
baseline. The participants then were
treated for 4 weeks by licensed physical therapists according to their random assignment of physical therapy
alone, physical therapy supplemented with graded exercise, or
physical therapy supplemented with
graded exposure. The participants
were reassessed on the same measures by a blinded evaluator 4 weeks
after randomization. The primary
analysis of the trial indicated no differences in 4-week outcomes for any
of the previously validated measures
used in this study. Therefore, participants were analyzed as a single cohort for the purpose of this study,
instead of in randomly assigned treatment groups.
Data Analysis
Reliability
cohort. Descriptive
analyses were generated and reported in the appropriate metric for
continuous and categorical variables.
Reliability analyses included analysis
of internal consistency (Cronbach alpha) for individual FDAQ items and
analysis of test-retest reliability (intraclass correlation coefficient [ICC]
[2,1]) for the total FDAQ score.
These results were reported with appropriate coefficient and 95% confidence interval (CI). From these data,
the standard error of measurement
(SEM) was calculated using a previously described method (standard
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deviation ⫻ 公(1 – test-retest reliability coefficient).28 –30 The minimal detectable change (MDC) also was calculated using a previously described
method (1.96⫻SEM).31
Validity cohort. Descriptive analyses were generated and reported in
the appropriate metric for continuous and categorical variables. Construct validity was assessed with factor analysis (principal component
analysis, varimax rotation with Kaiser normalization) at baseline and 4
weeks. Concurrent validity was assessed by reporting correlations
(Pearson r) of the FDAQ with the
FABQ, PCS, PIS, NRS for pain intensity, and ODQ at baseline and 4
weeks.
Concurrent validity was assessed further by separate multiple regression
models for baseline and 4-week measures. These models tested FDAQ
contributions to disability or physical impairment after controlling for
pain intensity and commonly implemented measures of FAM variables.
The independent variables for these
regression analyses were the FDAQ,
NRS for pain intensity, FABQ-PA,
FABQ-W, and PCS. The ODQ and PIS
were the dependent variables for
these models. These analyses would
provide information on the FDAQ in
relation to previously established
measures, as well as whether the assessment of the FAM should include
general and specific measures.
Predictive validity was assessed by
investigating
whether
baseline
FDAQ scores contributed additional
variance to 4-week outcomes for disability and physical impairment. In
these models, the baseline scores for
the ODQ and PIS first were entered
into the model to predict the respective 4-week outcomes. In the second
step of the models, the NRS for pain
intensity, FABQ-PA, FABQ-W, PCS,
and FDAQ were considered in a stepwise manner. These analyses pro-
Number 9
vided information on whether the
FDAQ could potentially be used as a
screening tool to predict outcomes
compared with the previously validated measures related to the FAM.
Predictive validity was assessed further by determining whether 4-week
changes in the FDAQ scores contributed additional variance to 4-week
changes for disability and physical
impairment. In these models, change
scores for the NRS for pain intensity,
FABQ-PA, FABQ-W, PCS, and FDAQ
were considered as predictors in a
stepwise manner for 4-week changes
in scores for the ODQ and PIS (separate models). These analyses provided information on whether
changes in the FDAQ scores were
associated with changes in accepted
outcome measures for LBP.26,27
Responsiveness was assessed by
paired t test and calculation of effect
size (Cohen d) for those participants
who completed the 4-week followup. The percentage of participants
from the reliability cohort who met
the MDC criterion was calculated to
provide a categorical estimate of
responsiveness.
Role of the Funding Source
Dr George (principal investigator),
Ms Valencia, and Dr Robinson received support from the National Institutes of Health/National Institute
of Arthritis and Musculoskeletal and
Skin Diseases (grant AR051128)
while preparing the manuscript.
Results
Descriptive statistics for baseline
measures of the reliability and validity cohorts are reported in Table 1.
Ninety-two percent (46/50) of the
participants in the reliability cohort
completed the 48-hour assessment,
with no differences in key variables
for those who completed and those
who did not complete the reliability
follow-up. The validity cohort was
followed for 4 weeks, with 85% (92/
108) of the participants providing
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Self-Report Measure of Fearful Activities for Patients With LBP
Table 1.
Baseline Characteristics for Reliability and Validity Cohortsa
Variable
Reliability Cohort (nⴝ50)
Age (y)
Validity Cohort (nⴝ108)
44.28 (18.47)
37.2 (14.5)
Female
43 (86.0%)
69 (63.9%)
Male
17 (14.0%)
39 (36.1%)
Currently employed
30 (60.0%)
62 (57.4%)
Work-related LBP
13 (26.0%)
22 (20.4%)
39 (78.0%)
66 (61.1%)
Fear of Daily Activities Questionnaire (potential range of scores⫽0–100)
24.9 (20.7)
37.3 (26.7)
Oswestry Disability Questionnaire (potential range of scores⫽0–100)
27.4 (17.8)
29.5 (16.2)
4.2 (2.2)
4.7 (2.1)
Sex
Duration of LBP (no. of weeks of present episode)
Prior history of LBP
7.5 (6.2)
Sudden onset of LBP
73 (67.6%)
Numerical rating scale for pain intensity (potential range of scores⫽0–10)
a
Fear-avoidance beliefs about physical activity (potential range of scores⫽0⫺24)
14.9 (5.5)
Fear-avoidance beliefs about work (potential range of scores⫽0⫺42)
13.4 (11.4)
Pain Catastrophizing Scale (potential range of scores⫽0–52)
16.3 (11.3)
Physical Impairment Scale (potential range of scores⫽0⫺7)
3.2 (1.9)
All values reported as mean (SD) or number (percentage). LBP⫽low back pain.
follow-up. For the validity cohort,
baseline age, sex, disability, pain intensity, fear-avoidance beliefs, pain
catastrophizing, and physical impairment scores were compared between those who completed and
those who did not complete the
4-week assessments. None of the
variables showed statistically significant (P⬎.05) differences for these
comparisons.
Reliability
At baseline, Cronbach alpha was .91
(95% CI⫽87–.95) for the FDAQ, suggesting high levels of internal consistency among FDAQ items. The 48hour test-retest reliability coefficient
for the FDAQ was .90 (95% CI⫽.82–
.94). Based on baseline data and
these reliability data, the SEM was
6.6, resulting in an MDC of 12.9.
Construct Validity
The baseline factor analysis identified a 2-factor solution, with eigenvalues of 6.3 (62.8% variance) and
1.1 (10.8% variance), respectively.
Factor loadings ranged from .59 to
September 2009
.92, with all 10 items loaded onto
these 2 factors (Tab. 2). The factors
created represented a loaded spine/
upright posture factor and a spinal
motion/seated posture factor.
The 4-week factor analysis identified
a 3-factor solution, with eigenvalues
of 4.3 (49.3% variance), 1.4 (13.5%
variance), and 1.1 (10.2% variance),
respectively. Factor loadings ranged
from .51 to .87, with all factors
loaded onto these 3 factors (Tab. 2).
The factors created were similar to
those of the baseline solution by including loaded spine and spinal motion factors. At 4 weeks, a postural
factor also was observed, as the
seated and upright posture items
were no longer split on the factor
solution. The item assessing fear of
performing back exercises was
cross-loaded on the postural and spinal motion factors. This item remained in the FDAQ for the remaining analyses because of its potential
for clinical utility.
Concurrent Validity
The correlation results for concurrent validity are summarized in Table
3. At baseline and 4 weeks, the
FDAQ scores were moderately correlated with scores on the FABQ-PA,
FABQ-W, PCS, NRS for pain intensity,
and PIS (Pearson r⫽.24 –.52, P⬍.05).
There were stronger correlations for
the ODQ at baseline and 4 weeks
(Pearson r ⫽ 0.70 and 0.49, P⬍
0.01).
The separate multiple regression
models predicting ODQ scores accounted for 57% of the variance at
baseline and for 51% of the variance
at 4 weeks (Tab. 4). At baseline, the
FDAQ was the strongest contributor
to variance in ODQ scores (␤⫽.52,
P⬍.01), and the FABQ-W also contributed to the model (␤⫽.20,
P⫽.01). At 4 weeks, the FDAQ contributed to disability (␤⫽.24,
P⫽.01), but in this case, pain intensity was the strongest contributor to
the model (␤⫽.49, P⬍.01).
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Self-Report Measure of Fearful Activities for Patients With LBP
Table 2.
Factor Loadings for Fear of Daily Activities Questionnairea
Loaded Spine/
Upright Posture
Baseline Analysis
Seated Posture/
Spinal Motion
1. Sitting for longer than 1 hour
.59
2. Standing for longer than 30 minutes
.64
3. Walking for longer than 30 minutes
.70
4. Lifting less than 20 pounds
.82
5. Lifting 20 pounds or more
.91
6. Carrying less than 20 pounds
.78
7. Carrying 20 pounds or more
.92
8. Twisting
.66
9. Reaching to the floor
.78
10. Performing back exercises
.89
4-Week Analysis
Loaded Spine
Upright and
Seated Postures
1. Sitting for longer than 1 hour
.75
2. Standing for longer than 30 minutes
.83
3. Walking for longer than 30 minutes
.59
4. Lifting less than 20 pounds
.82
5. Lifting 20 pounds or more
.84
6. Carrying less than 20 pounds
.87
7. Carrying 20 pounds or more
.79
8. Twisting
.81
9. Reaching to the floor
.77
10. Performing back exercises
a
Spinal
Motion
.51
.54
Only loading factors greater than .50 reported in table.
The separate multiple regression
models predicting PIS scores accounted for 28% of the variance at
baseline and for 21% of the variance
at 4 weeks (Tab. 4). At baseline, the
FDAQ contributed to variance in PIS
scores (␤⫽.21, P⫽.05), as did pain
intensity (␤⫽.39, P⬍.01) and the
FABQ-W (␤⫽.20, P⫽.04). At 4
weeks, only pain intensity uniquely
contributed to the variance in PIS
scores (␤⫽.35, P⬍.01).
Predictive Validity
Baseline ODQ scores accounted for
11.4% of the variance in 4-week
ODQ scores (F1,90⫽11.6, P⬍.01).
Only the FABQ-W was added to this
model, and it accounted for an additional 4.1% of variance in 4-week
ODQ scores (F1,89⫽4.3, P⫽.04).
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Table 3.
Correlations (Pearson r) Between Fear of Daily Activities Questionnaire (FDAQ) Scores
and Scores on Previously Validated Measures: Concurrent Validitya
Correlation
Baseline
4 Weeks
FDAQ and FABQ-PA
.45*
.31*
FDAQ and FABQ-W
.34*
.24**
FDAQ and PCS
.52*
.35*
FDAQ and ODQ
.70*
.49*
FDAQ and NRS
.34*
.36*
FDAQ and PIS
.31*
.26**
a
FABQ-PA⫽Fear-Avoidance Beliefs Questionnaire physical activity scale, FABQ-W⫽Fear-Avoidance
Beliefs Questionnaire work scale, PCS⫽Pain Catastrophizing Scale, ODQ⫽Oswestry Disability
Questionnaire, NRS⫽numerical rating scale for pain intensity, PIS⫽Physical Impairment Scale. * P⬍.01,
** P⬍.05.
Baseline PIS scores accounted for
20.5% of the variance in 4-week PIS
scores (F1,78⫽20.2, P⬍.01). No
other variables were entered into the
model for the PIS. In the predictive
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analyses that incorporated change
scores, change in NRS scores accounted for 27.8% of the variance in
ODQ change scores (F1,90⫽34.7,
P⬍.01). Change in FDAQ scores was
September 2009
Self-Report Measure of Fearful Activities for Patients With LBP
Table 4.
Hierarchical Regression Analysis for Fear of Daily Activities Questionnaire (FDAQ) and Disability and Physical Impairment:
Concurrent Validitya
Baseline Model for Disability
(R2ⴝ.57, P<.01)
Measure
␤
4-Week Model for Disability
(R2ⴝ.51, P<.01)
P
VIF
␤
P
VIF
NRS
.13
.09
1.3
.49
⬍.01
1.3
FABQ-PA
.07
.37
1.5
.05
.57
1.2
FABQ-W
.20
.01
1.3
.11
.21
1.1
PCS
.06
.45
1.5
.10
.21
1.1
FDAQ
.52
⬍.01
1.6
.24
.01
1.3
Baseline Model for Physical Impairment
(R2ⴝ.28, P<.01)
␤
NRS
FABQ-PA
FABQ-W
PCS
FDAQ
P
VIF
4-Week Model for Physical Impairment
(R2ⴝ.21, P<.01)
␤
P
VIF
.39
⬍.01
1.2
.35
⬍.01
1.3
⫺.06
.57
1.4
.05
.67
1.3
.20
.04
1.2
.06
.63
1.3
⫺.12
.26
1.4
⫺.08
.47
1.2
.21
.05
1.5
.13
.31
1.4
a
FABQ-PA⫽Fear-Avoidance Beliefs Questionnaire physical activity scale, FABQ-W⫽Fear-Avoidance Beliefs Questionnaire work scale, PCS⫽Pain
Catastrophizing Scale, ODQ⫽Oswestry Disability Questionnaire, NRS⫽numerical rating scale for pain intensity, VIF⫽variance inflation factor (provided as
estimate of collinearity).
added to the model, and it accounted
for an additional 15.0% of the variance in ODQ change scores
(F1,89⫽23.3, P⬍.01). Change in NRS
scores accounted for 12.4% of the
variance in PIS scores (F1,78⫽11.8,
P⬍.01). No other variables were entered into the model for the PIS.
Responsiveness
Mean FDAQ scores decreased from
36.2 (SD⫽24.5) to 17.9 (SD⫽16.2)
over 4 weeks (P⬍.01), with a corresponding effect size of 0.86. The
MDC for the FDAQ was met or exceeded by 55.4% (51/92) of this
cohort.
Discussion
This study investigated the psychometric properties of the FDAQ, a
novel self-report questionnaire for
rating fearful activities. The FDAQ
was used for activity selection in a
clinical trial that studied physical
therapy supplemented with graded
exposure,20 but it had not been subjected to detailed psychometric analSeptember 2009
yses. Collectively, the analyses presented in this article suggest that the
FDAQ may be an appropriate measure to determine fear levels of specific activities in outpatient physical
therapy settings.
Our analyses indicated that baseline
FDAQ scores did not explain additional variance in disability and physical impairment outcomes. Therefore, it would be inappropriate to
recommend routine use of the FDAQ
as a general screening tool for all
patients with LBP. Clinical implementation of the FDAQ may be appropriate after elevated pain-related
fear is detected with a measure that
has demonstrated predictive validity,
such as the FABQ. Instead, our analyses indicated that the FDAQ had
strong associations with current disability and weak associations with
current impairment and that changes
in FDAQ scores were predictive of
changes in disability. The FDAQ was
responsive to change, as approximately 55% of the participants met
or exceeded the MDC of 12.9 during
the 4 weeks of treatment. Collectively, these data indicate the FDAQ
should be used as a focused measurement tool for determining activities
to incorporate into graded exposure
physical therapy treatment plans and
as a way to monitor changes in patient fear levels.
The FDAQ had a clinically viable factor solution, indicating patients with
acute or subacute LBP have a fear of
loaded spine activities, postural components, and specific spinal motions.
The FDAQ was significantly correlated with established measures, but
shared only a maximum of 25% variance with the PCS, so construct redundancy with other FAM variables
did not appear to be a concern.
Stronger evidence for the FDAQ
comes from multiple regression
models for disability in which concurrent validity was demonstrated
through unique contribution to variance in ODQ scores at baseline (with
the FABQ-W) and at 4 weeks (with
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Self-Report Measure of Fearful Activities for Patients With LBP
the NRS for pain intensity). Predictive validity was demonstrated
through unique contribution of
FDAQ change scores to variance in
ODQ change scores (with changes in
NRS for pain intensity). The FDAQ
also was associated with physical impairment, but not as strongly as with
disability. The univariate correlation
for physical impairment was smaller,
and the FDAQ demonstrated only
concurrent validity through unique
contribution to variance in baseline
PIS scores (with the FABQ-W and
NRS for pain intensity). A potential
reason for this finding might be that
the 2 FDAQ factors that explained
the most variance (loaded spine and
postural components) are more consistent with disability or functional
limitations compared with physical
impairment.
The FDAQ is a novel measure, but it
is not the only way to assess fear of
specific activities for patients with
musculoskeletal pain. The Photograph Series of Daily Activities–Short
Electronic Version was developed by
Leeuw et al32 for the assessment of
perceived harmfulness of daily activities in patients with chronic LBP,
and it has been shown to have good
reliability and validity. The Pictorial
Fear of Activity Scale–Cervical was
developed by Turk et al33 for the
assessment of factors that determine
demands on the neck, and it also has
been shown to have good reliability
and validity. These pictorial measurement techniques have the advantage
of depicting the activity in even
more detail than is available when
using a self-report measure of activity.32,33 For example, the exact size,
shape, and nature of the object that
the patient is lifting or carrying are
depicted in pictorial methods. However, these techniques also were developed in comprehensive chronic
pain programs that have more time
allotted for psychological assessment
than in a typical outpatient physical
therapy visit for LBP. Therefore, we
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made the decision to implement a
pragmatic self-report measure in our
clinical trial. This decision seems to
be supported by these psychometric
analyses, but future studies directly
comparing pictorial with self-report
techniques are necessary to make an
informed decision on assessment of
fearful activities.
In addition to generating psychometric information on the FDAQ, this
study provides theoretical information on the FAM. Our results suggest
that fear of specific activities may
contribute to the disablement process from LBP, with less of an influence on physical impairment. The
FDAQ consistently contributed variance to disability in concurrent and
predictive analyses, perhaps because
this measure accounts for specific
fears related to loading the spine,
sustaining upright and seated postures, and performing certain spinal
motions. Other FAM-related measures included similar items, but the
level of specificity provided by the
FDAQ explained additional variance
in disability scores, even in multivariate settings including established
measures of pain intensity, fearavoidance beliefs, and pain catastrophizing. Support for fear of specific activity assessment also has
been reported in studies using pictorial measurement techniques,32,33
providing preliminary evidence that
is consistent with recent recommendations about the FAM and selfreport of disability. Comprehensive
assessment may need to incorporate
both general beliefs about painrelated fear and beliefs about specific
activities.1
Limitations of the current study include that we planned to recruit only
50 participants for the reliability cohort because this size is adequate for
test-retest analyses. However, this
decision resulted in an inadequate
sample size to perform another factor analysis on these participants.
Number 9
Future studies should incorporate
samples that are large enough to determine whether the factor solutions
described in this report are replicated in different physical therapy
settings. Another limitation is that
there was one item on the FDAQ that
cross-loaded (related to fear of performing back exercise), which is not
ideal for a questionnaire. However,
we included the cross-loaded item in
subsequent analyses because this
item may have direct clinical relevance for physical therapists who
will be prescribing back exercises.
Future studies should consider
whether modifications to this item
are necessary. For example, clarification of the type of back exercises
being performed, as well as the effect of this clarification on factor
structure, could be implemented in
future versions of the FDAQ.
The ODQ levels reported in this
study were comparable across the
reliability and validity cohorts, but
they corresponded with moderate
disability overall. Therefore, these
findings may not be applicable for
patients with higher intake ODQ
scores. We reported concurrent and
predictive associations with the
FDAQ and an established self-report
of disability, the ODQ.26,27 These associations are encouraging, but also
could be related to both questionnaires being self-report, with items
related to spine posture and loading
of the spine. We found weaker associations with the FDAQ and our measure of physical impairment (PIS),
and future study is necessary to determine whether the FDAQ also is
related to physical impairment or
other physical performance measures.
Another limitation is that we did not
assess why patients were fearful of
certain activities. The exact reasons
for their fear were beyond the intended scope of this study. However, these reasons may be important to consider in the rehabilitation
September 2009
Self-Report Measure of Fearful Activities for Patients With LBP
process, and future research is necessary to investigate that possibility.
Last, as previously mentioned, we
did not include the open-ended responses in these analyses. This decision was made because there was
variability among participants in
completing these items, while all
participants completed the first 10
items. In addition, when open-ended
responses were provided, there
were noticeable differences in the
quality of responses, making direct
comparisons difficult. Furthermore,
the open-ended responses were not
always the highest-rated activities for
fear, and some responses were not
appropriate for rehabilitation in traditional outpatient rehabilitation settings (eg, fear of pain during sexual
intercourse), whereas other responses were related to general fears
(eg, fear of skydiving). We believe
the open-ended responses may have
value for clinical decision making in
specific situations, but future research is necessary to determine the
empirical role open-ended responses
play in the FDAQ.
Conclusion
The FAM has received empirical support in the literature, but there are
still lingering questions regarding its
clinical application. One remaining
issue is whether it is adequate to
assess general beliefs consistent with
the FAM, or whether it is necessary
to assess fear of specific activities.
This study suggests that the FDAQ is
a potentially viable measure to determine fear of specific activities in
physical therapy settings because it
has sound psychometric properties,
including a viable factor solution, adequate test-retest reliability, and responsiveness, contributing unique
variance to self-report of disability in
concurrent and predictive analyses.
Future research is needed to confirm
the factor solution of the FDAQ and
to assess whether these findings are
applicable to other samples of patients with LBP.
September 2009
Dr George and Dr Robinson provided concept/idea/research design and writing. Ms
Valencia and Mr Zeppieri provided data collection and consultation (including review of
manuscript before submission). Dr George
and Ms Valencia provided data analysis. Dr
George provided project management and
fund procurement. Mr Zeppieri provided
participants. The authors thank Jim Atchison,
Virgil Wittmer, and Anita Davis for input on
items for the FDAQ. They also thank Michael
Borut, Melissa Cere, Anthony Cere, Michael
Hodges, and Dalton Reed for assistance with
participant recruitment and data collection.
This study was approved by the University of
Florida Institutional Review Board.
The data were part of a poster presentation
at the 28th Annual Scientific Meeting of the
American Pain Society; May 7, 2009; San
Diego, California.
Dr George (principal investigator), Ms Valencia, and Dr Robinson received support from
the National Institutes of Health/National Institute of Arthritis and Musculoskeletal and
Skin Diseases (grant AR051128) while preparing the manuscript.
This article was received February 3, 2009, and
was accepted May 22, 2009.
DOI: 10.2522/ptj.20090032
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Self-Report Measure of Fearful Activities for Patients With LBP
Appendix.
Fear of Daily Activities Questionnairea
People with low back pain have told us that they are fearful of performing certain activities because they believe
these activities will cause additional low back pain or reinjure their back.
Examples of such activities are listed below. Using the provided scale, please rate each activity for the amount of fear
it causes you, as it relates to your low back pain. Because not all activities are fearful for all people, we are also asking
you to list two different activities that cause you fear and to rate the fear associated with those activities.
0
⬍
⬎
(No fear of activity)
100
(Maximal fear of activity)
Activity
Rating (0 –100)
1. Sitting for longer than 1 hour
____________
2. Standing for longer than 30 minutes
____________
3. Walking for longer than 30 minutes
____________
4. Lifting less than 20 pounds
____________
5. Lifting 20 pounds or more
____________
6. Carrying less than 20 pounds
____________
7. Carrying 20 pounds or more
____________
8. Twisting
____________
9. Reaching to the floor
____________
10. Performing back exercises
____________
11. _________________________
____________
12. _________________________
____________
a
Reproduced with permission of the Orthopaedic and Sports Physical Therapy Section of the American Physical
Therapy Association from: George SZ, Zeppieri G. Physical therapy utilization of graded exposure for patients with
low back pain. J Orthop Sports Phys Ther. 2009;39:496 –505, Epub 24 February 2009, doi: 10.2519/jospt.2009.2983.
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