The Journal of Pain, Vol 8, No 9 (September), 2007: pp 708-717
Available online at www.sciencedirect.com
Coping Predictors of Children’s Laboratory-Induced Pain
Tolerance, Intensity, and Unpleasantness
Qian Lu,* Jennie C. I. Tsao,* Cynthia D. Myers,† Su C. Kim,* and Lonnie K. Zeltzer*
*Pediatric Pain Program, Department of Pediatrics, David Geffen School of Medicine, University of California
Los Angeles, Los Angeles, California.
†
Integrative Medicine Program, Department of Interdisciplinary Oncology, H. Lee Moffitt Cancer Center &
Research Institute, Tampa, Florida.
Abstract: This study examined coping predictors of laboratory-induced pain tolerance, intensity,
and unpleasantness among 244 healthy children and adolescents (50.8% female; mean age, 12.73 ⴞ
2.98 years; range, 8 –18 years). Participants were exposed to separate 4-trial blocks of pressure and
thermal (heat) pain stimuli, as well as 1 trial of cold pain stimuli. Strategies for coping with pain were
measured using the Pain Coping Questionnaire (PCQ). Linear regression analyses were conducted to
examine the associations between the 8 PCQ subscales and pain responses (pain tolerance, intensity,
and unpleasantness) to all 3 pain tasks, controlling for age and sex. We found that internalizing/
catastrophizing predicted higher pain intensity across the 3 pain tasks and higher cold pain
unpleasantness; seeking emotional support predicted lower pressure pain tolerance; positive
self-statements predicted lower pressure pain intensity and lower cold pain intensity and unpleasantness; and behavioral distraction predicted higher pressure pain tolerance and lower heat
pain unpleasantness. These results suggest that in healthy children, internalizing/catastrophizing,
and seeking emotional support may be conceptualized as pain-prone coping strategies, and
positive self-statements and behavioral distraction as pain-resistant coping strategies within the
context of laboratory pain.
Perspective: These results support investigation of interventions with children that aim to reduce
acute pain responses by modifying coping to reduce seeking of emotional support and catastrophizing
and enhance the use of positive self statements and behavioral distraction.
© 2007 by the American Pain Society
Key words: Laboratory pain, children, seeking emotional support, positive self-statements, internalizing/catastrophizing, distraction.
T
he study of pre-existing coping strategies within
the context of laboratory induced pain has important clinical implications for the management of
children undergoing painful medical procedures.25 In
contrast to clinical pain studies where it is difficult to
partial out the influence of highly variable pain sympReceived December 8, 2006; Revised March 23, 2007; Accepted April 30,
2007.
Supported by R01DE012754, awarded by the National Institute of Dental
and Craniofacial Research, and UCLA General Clinical Research Center
Grant MO1-RR-00865 (PI: Lonnie K. Zeltzer). Dr. Lu is supported by UCLA
Jonsson Comprehensive Cancer Center Postdoctoral Fellowship.
Address reprint requests to Qian Lu, PhD, MD, Pediatric Pain Program,
Department of Pediatrics, David Geffen School of Medicine at UCLA,
10940 Wilshire Blvd, Suite 1450, Los Angeles, CA 90024. E-mail:
qlu@ucla.edu
1526-5900/$32.00
© 2007 by the American Pain Society
doi:10.1016/j.jpain.2007.04.005
708
toms on coping strategies, laboratory pain studies have
the advantage of controlling the administration of painful stimuli across participants. The recent development
of the Pain Coping Questionnaire (PCQ)27 provides a
standardized instrument to assess how children cope
with pain. Only 1 study25 has examined how pre-existing
coping strategies assessed by the PCQ predicted laboratory pain responses in children. However, this study excluded the subscales of the PCQ, which assessed behavioral distraction and seeking social support, and these
constructs represent potentially important aspects of
pain-related coping.
The PCQ contains 3 higher-order factors and 8 subscales.
Avoidance coping includes 2 subscales (catastrophizing
and externalizing); approach coping includes 4 subscales
(information seeking, problem solving, positive selfstatement, and seeking social support); and distraction
ORIGINAL REPORT/Lu et al
Figure 1. Theoretical model of coping and laboratory pain
outcomes. Solid line indicates hypothesized positive association
between coping and pain responsivity and the dotted line indicates hypothesized negative association between coping and
pain responsivity. No hypothesized associations were advanced
for the coping subscales of externalizing, information seeking,
and problem solving. Note that increased pain responsivity is
indicated by lower pain tolerance, higher pain intensity, and
unpleasantness.
coping includes 2 subscales (behavioral distraction and
cognitive distraction) (Fig 1). Overwhelming evidence
suggest that behavioral and cognitive distraction copings are associated with reduced pain,1,5,6,19 whereas
catastrophizing is associated with increased pain.17,28,29
Some preliminary evidence suggests that positive selfstatements, which represent an active strategy of affirming “everything will be ok” was associated with
less pain among children with juvenile idiopathic arthritis32; seeking emotional support, which might represent a passive strategy for attempting to get sympathy by amplifying pain or worries,36 was associated
with higher headache severity in schoolchildren1 and
higher emotional distress in children experiencing
pain associated with rheumatologic diseases.35 Mixed
findings have been reported for information seeking,
problem solving,1,33 and externalizing.1,5,32 Despite
evidence supporting the existence of 3 higher-order
PCQ factors,27 the above results highlight the need to
examine individual PCQ subscales in studies on children’s pain coping.
As noted above, only 1 prior study25 has examined the
relationship between the PCQ subscales and laboratory
pain responses in children. Not only were key PCQ subscales excluded, only 1 aspect of the pain response,
pain tolerance, was examined in this earlier study. Pain
intensity and pain unpleasantness are important dimensions of pain responsivity that may be separately
influenced by various psychological factors.26 We have
previously demonstrated age and sex differences in
laboratory pain responses20 and, therefore, it was important to examine whether the PCQ subscales explained additional variance above and beyond age
and sex. The current study thus examined the associations between the 8 individual PCQ subscales and pain
709
tolerance, intensity and unpleasantness of 3 different
types of laboratory pain stimuli (cold, heat, pressure)
in a sample of healthy children, controlling for child
age and sex. We assessed pain tolerance rather than
pain threshold because our pilot work revealed that the
assessment of pain threshold interfered with children’s
natural coping style by influencing them to attend to the
painful stimuli. It was hypothesized that for all 3 types of
pain stimuli: 1) internalizing/catastrophizing and seeking emotional support would predict increased pain
responses (ie, lower pain tolerance, and higher pain
intensity and unpleasantness), and 2) positive selfstatements and behavioral/cognitive distraction would
predict lower pain responses. In light of the mixed
findings to date, we explored the associations between pain responsivity and the remaining 3 coping
strategies (ie, externalizing, problem solving, and information seeking).
Methods
Participants
The University of California, Los Angeles (UCLA) Institutional Review Board (IRB) as well as the IRBs for recruitment sites approved all recruitment and study procedures. Participants were recruited from a major urban
area through mass mailing, posted advertisements, and
classroom presentations. Initial eligibility was confirmed
by telephone: All 489 individuals were screened for eligibility by telephone; 17 children (3.5% of those screened)
were excluded due to ongoing acute or chronic illness, or
use of medications that could affect study outcomes. Of
the 472 (96.5%) invited to participate, 228 (48%) declined participation mainly because of parental lack of
interest (54%) or time (21%).
In total, 244 healthy children (124 female; 50.8%) with
a mean age of 12.73 years (SD ⫽ 2.98 years; range, 8 –18
years) participated in the study. The average ages of
males and females were 12.44 years (SD ⫽ 2.89) and
13.01 years (SD ⫽ 3.05 years), respectively. The ethnic
composition of the sample was 40.2% Caucasian, 23.8%
Hispanic, 13.9% African-American, 9.8% Asian-American, and 12.3% other. Parent socioeconomic status14
was: Unskilled workers 3.7%, semi-skilled workers 4.1%,
clerical/sales 11.9%, technical 41.8%, and professional
34.8%.
Overview of Procedure
The UCLA IRB approved all study procedures. Both parents and children were informed by an experimenter
about the study, which was described as an investigation
on how children experienced pain. Parents and children
signed consent and assent forms, respectively. Participants received a $30 video store gift certificate and a
t-shirt for their participation. On the day of the laboratory session, participants and their parents were greeted
by an experimenter and escorted to separate rooms;
there was no contact between them until after the session was finished. After participants completed ques-
710
tionnaires (described below) in a quiet room, they were
escorted individually to the laboratory. Participants were
instructed on the use of the visual analog scales (VAS) for
rating pain intensity and unpleasantness (see below for
detailed descriptions). Participants were then exposed to
3 pain tasks: Pressure, heat, and cold pressor. For pressure and heat pain tasks we used 2 sites to avoid local
sensitization or habituation, and we used 2 magnitudes
of stimulus to allow for greater variation in pain response. Each pressure and heat pain task included 4 trials
presented separately in counterbalanced order (setting
and site of exposure) across participants. The cold pressor
tasks consisted of 1 trial with a 1 minute informed ceiling
(CPT-1) and 1 trial with a 3 minute uninformed ceiling
(CPT-3). The CPT-3 has been discussed elsewhere34 and
this paper focused on CPT-1. Before the start of each
trial, subjects were informed that they would experience
moderate sensation that might eventually be perceived
as pain. Participants were instructed to continue with the
task for as long as they could and to remove their finger
or arm from the apparatus at any time during the procedures if it became too uncomfortable or painful. All tasks
were extensively piloted on volunteers in the targeted
age range.
Coping Predictors of Children’s Laboratory Pain
quickly and will cause some discomfort. Keep your arm
on the spot as long as you can, but you are free to remove
your arm at anytime.”
Cold Pressor Task (CPT-1)
Participants underwent a trial of 10°C water using a
commercial ice chest measuring 38 cm wide, 71 cm long,
and 35 cm deep. A plastic mesh screen separated crushed
ice from a plastic large-hole mesh armrest in the cold
water. Water was circulated through the ice by a pump
to prevent local warming about the hand. Participants
were instructed to keep the dominant hand in cold water
to a depth of 2 inches above the wrist for as long as they
could for an informed 1-minute period. Participants
were instructed, “In this cooler is cold water. I am going
to ask you to put 1 hand in the water and to keep it in for
as long as you possibly can. When you put your hand in,
do it with the palm of your hand facing up towards the
ceiling, so that the back of your hand lays flat against the
surface of the grate. I am going to ask you to leave your
hand in for 1 minute. I will tell you when the time is up.
When the time is up, you will take your hand out of the
water. Try to keep your hand in until I tell you to take it
out, but, if you need to, you can take it out before I tell
you to.”
Laboratory Pain Tasks
Pressure Task
The Ugo Basile Analgesy-Meter 37215 (Ugo Basile Biological Research Apparatus, Comerio, Italy) was used to
administer focal pressure through a lucite point approximately 1.5 mm in diameter to the second dorsal phalanx
of the middle finger and index finger of each hand. Four
trials, 2 at each of 2 levels of pressure (322.5 g and 465 g),
were run with an uninformed ceiling of 3 minutes. A
comparable device has been used in healthy and clinical
pediatric samples (ages 5–17 years) without adverse effects.7 Participants were instructed as follow: “During
this task you will experience pressure on your finger.
When I ask you to, you will place either your index or
middle finger and the location onto this flat surface and
I will lower this point onto your finger. The point should
contact your finger at the spot I marked earlier. Leave
your finger in place for as long as you can but you are
free to remove the weight at any time. To remove the
weight, lift this lever up like so.”
Thermal Heat Task
The Ugo Basile 7360 Unit (Ugo Basile Biological Research Apparatus) was used to administer a total of 4
trials of 2 infrared stimulus intensities15,20 of radiant
heat 2 inches proximal to the wrist and 3 inches distal to
the elbow on both volar forearms with an uninformed
ceiling of 20 seconds. Thermal pain tolerance was electronically measured with an accuracy of 0.1 seconds. A
similar task has been used in a sample aged 6 to 17 years
without adverse effects.22 Participants were instructed
as follow: “This part of the experiment will involve heat.
When you are ready, you will place your forearm over a
small spot on this metal block. This spot will heat up
Laboratory Pain Measures
Pain Tolerance
Pain tolerance was defined as time in seconds elapsed
from the onset of the pain stimulus to the participant’s
withdrawal from the stimulus. Tolerance was measured
for all 3 tasks (pressure, thermal heat, and cold).
Pain Intensity and Pain Unpleasantness
Pain intensity and pain unpleasantness were assessed
through a vertical sliding visual analogue scale (VAS) immediately after each trial. The VAS is brief, easily understood, and sensitive to changes in pain. With excellent
psychometric properties,11 it can be used by children in
the age range included in the current study (8 –18 years
of age).21 Prior research has used the VAS to rate pain in
children in laboratory pain tasks.23
Participants were asked to rate their pain using the
slider VAS, which was anchored with 0 at the bottom and
10 at the top. The scale also had color cues, graded from
white at the bottom to dark red at the top, as well as a
neutral face at the bottom and a negative facial expression at the top. Participants were given the following
instructions regarding the use of VAS. “This scale is like a
thermometer, only rather than measure your temperature; we will use it to measure your feeling or mood.
The white color on the bottom represents the lowest
values and the dark red at the very top represents the
highest values for a particular feeling. By using this
thermometer you’ll let me know how much pain or
discomfort you feel. You will do this by sliding the bar
up and down on the colors until you get to the shade
that equal how you feel.” Three practice ratings were
completed to ensure that participants understood the
ORIGINAL REPORT/Lu et al
VAS. The practice trials asked: (1) “How afraid or nervous
would you be right before taking an important exam or
test?’’ (2) “How much would it bother you to eat your
favorite dessert?’’ (3) “How afraid, nervous, or worried
do you feel right now?’’ The instructions and practice
trials were repeated until participants fully understood
the VAS.
Pain intensity. Immediately after each trial, participants were asked to use the VAS and rate the amount of
pain they experienced during the task. Participants were
asked, “At its worst, how much pain did you feel?” during the task.
Pain unpleasantness. Immediately after each trial and
after rating the pain intensity, participants were also
asked to rate the amount of distress or bother they experienced during the task using the same vertical sliding
VAS. This time, participants were asked, “at its worst,
how much did the task bother you?”
Questionnaire Measure: Pain Coping
Strategies
Pain coping strategies were measured using the PCQ.27
Children completed the PCQ with respect to how they
dealt with general pains that lasted a few hours or days
by rating the frequency of how often each coping strategy was used ranging from “never ⫽ 1”, “hardly ever”,
through “sometimes”, “often”, to “very often ⫽ 5.” The
PCQ is a 39-item questionnaire that was developed and
validated in relation to self-report responses to questionnaires and dolorimeter pressure pain threshold with
samples of children age 8 and older. It has 8 subscales:
1) seeking social support with a focus on seeking emotional
support and empathy (5 items, “let my feelings out to a
friend”), 2) information seeking (4 items, eg, “find out
more information”), 3) problem solving (6 items, eg,
“figure out what I can do about it”), 4) positive selfstatements (5 items, eg, “say to myself, things will be
ok”), 5) behavioral distraction (4 items, eg, “do something fun”), 6) cognitive distraction (5 items, “ignore the
situation”), 7) externalizing (5 items, eg, “get mad and
throw or hit something”), and 8) internalizing/catastrophizing (5 items, eg, “worry that I will always be in
pain”).
Statistical Analysis
Independent sample t tests were used to examine
mean differences in the PCQ subscales between boys and
girls. Bivariate analyses were used to preliminarily examine relationships among the variables before multivariate modeling. Pearson product moment correlation coefficients were generated to explore the associations
between the 8 PCQ subscales and the laboratory pain
responses. In confirmatory analyses, sequential linear regression was used to predict pain outcomes from the 8
PCQ subscales simultaneously, controlling for age and
sex. The demographic variables (age and sex) were entered as predictors in the first step (Step 1) of the regression analyses, followed by the 8 coping subscales together in the second step (Step 2). Adjusted R2 is
reported for model fit (note that adjusted R2 is a more
711
2
stringent criterion than R to determine model fit because adjusted R2 can decline in value if the contribution
to the explained variance by the additional variable is
less than the impact on the increased degrees of freedom). R2 increments from Step 1 to Step 2 were reported
to show the additional variance explained by the coping
predictors above and beyond the effects of age and sex
(note that the R2 increments are the difference of the
unadjusted R2 between the 2 steps).
A standard ␣ level of .05 (two-tailed) was used to evaluate the preliminary bivariate results. Bonferroni-Holm
step-down test15 was used to reduce the likelihood of
Type I error associated with conducting the confirmatory
multiple regression tests. We ordered the P values for all
the regression models from lowest to highest, and then
compared these P values with corresponding critical values of ␣ according to the Bonferroni-Holm step-down
test (these values were indicated in Table 3). Critical cutoff values of ␣ were calculated using this formula, ␣ ⫽
0.05/k, and k ⫽ n, n-1, n-2, n-3 . . ., 1 (n ⫽ the total number of regression models). If the P value was less than the
critical value, then null-hypothesis would be rejected and
the next P value would be compared with the next critical value. If the P value was larger than the critical value,
the null-hypothesis would not be rejected, and comparison would be stopped.
Pain intensity ratings for the thermal and pressure
tasks were highly correlated across the 4 trials within
each task (r’s ⫽ .71–.89, P ⬍ .001). Pain unpleasantness
ratings for the thermal and pressure tasks were highly
correlated across the 4 trials within each task (r’s ⫽
.72–.88, P ⬍ .001). Pain tolerance for the thermal and
pressure tasks were also highly correlated across the 4
trials within each task (r’s ⫽ .55 –.78, P ⬍ .001). Therefore,
these data were averaged across trials yielding a single
mean rating for pressure intensity, heat intensity, pressure unpleasantness, heat unpleasantness, pressure tolerance, and heat tolerance, respectively.
Outliers and distributions of the dependent variables
were examined before multivariate modeling. The number of participants that reached the tolerance ceiling for
the pressure, heat, and cold tasks were 1, 20, and 79,
respectively. Given the large number of participants who
reached the ceiling in the heat and cold tasks (20 and 79,
respectively), additional analysis was conducted to examine predictors of pain tolerance in a subset of the sample
who did not reach ceiling, as well as predictors of
whether or not ceiling was reached. The results using the
whole sample were confirmed in the subset that did not
reach ceiling as well as in the analysis for predicting
whether ceiling was reached or not. Pressure pain tolerance was not normally distributed and therefore a log
transformation was used to normalize the distribution. Furthermore, cases were monitored for undue
influence on the final models; however, none were
determined to have standardized residuals in excess of
3 standard deviations. Residuals for all models were
normally distributed.
712
Coping Predictors of Children’s Laboratory Pain
Table 1. Descriptive Statistics of Laboratory Pain Responses and PCQ Subscales With
Reliabilities of PCQ Subscales
Seeking emotional support
Information seeking
Problem solving
Positive self-statements
Behavioral distraction
Cognitive distraction
Externalizing
Internalizing/catastrophizing
Mean pressure tolerance
Mean heat tolerance
Cold tolerance
Mean pressure VAS intensity
Mean heat VAS intensity
Cold VAS intensity
Mean pressure VAS unpleasantness
Mean heat VAS unpleasantness
Cold VAS unpleasantness
N
MINIMUM
MAXIMUM
MEAN
STD. DEVIATION
RELIABILITY
242
242
242
242
242
242
242
242
239
240
239
239
240
240
187
188
188
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
2.22
1.05
0.83
0.00
0.00
0.00
0.00
0.00
0.00
5.00
5.00
5.00
5.00
5.00
5.00
5.00
4.60
180.00
20.00
60.00
9.76
9.76
10.00
9.76
9.76
9.76
3.03
2.63
3.32
3.22
3.47
3.24
1.63
1.93
40.27
10.77
47.77
4.87
4.99
3.97
3.49
3.48
3.23
1.03
0.94
0.94
0.92
0.88
0.87
0.69
0.73
45.71
5.14
17.09
2.60
2.77
3.08
2.62
2.69
2.97
0.83
0.42
0.74
0.85
0.83
0.82
0.76
0.75
—
—
—
—
—
—
—
—
—
NOTE: Unpleasantness VAS was not administered until after the study started and thus, the n for the pain unpleasantness ratings is smaller than the other
measures. Tolerance is in seconds.
Results
Descriptive Statistics for PCQ Subscales
and Laboratory Pain Responses
Table 1 shows descriptive statistics of laboratory pain
responses and the PCQ subscales including the reliability
of each of the subscales. Overall, the PCQ subscales were
reliable, with Cronbach’s ␣ ranging from 0.74 – 0.83, except for the information seeking subscale with Cronbach’s ␣ of 0.42. Note that pain unpleasantness VAS was
not administered until after data collection was underway and thus, the n for the pain unpleasantness ratings is
smaller than that for the other measures.
Age and Sex Differences in PCQ
Subscales
Older participants were more likely to use more problem-solving and externalizing coping strategies than
Table 2.
younger participants. The associations between age
and problem solving, and age and externalizing were
r ⫽ .22 (P ⬍ .001), and r ⫽ .16 (P ⫽ .02), respectively.
However, there were no significant correlations between age and the other PCQ subscales. Independent
sample t tests were used to examine mean differences
in the PCQ subscales between boys and girls. Females
were more likely to use seeking emotional support as a
coping strategy than males (t ⫽ 5.02, P ⬍ .001, df ⫽
240). No sex differences were found in the other 7 PCQ
subscales.
Exploration of Bivariate Correlations
Between Coping Subscales and
Laboratory-Induced Pain Outcomes
Bivariate analyses were used to preliminarily examine relationships among the variables before multivariate modeling. Table 2 shows the significant correla-
Bivariate Correlations Between PCQ Subscales and Laboratory Pain Response
PCQ SUBSCALES
Internalizing/catastrophizing
Seeking emotional support
Positive self-statements
Behavioral distraction
Cognitive distraction
PRESSURE PAIN
TOLERANCE
PRESSURE PAIN
INTENSITY
HEAT PAIN
INTENSITY
0.23*
0.28*
COLD PAIN
INTENSITY
0.24*
HEAT PAIN
UNPLEASANTNESS
COLD PAIN
UNPLEASANTNESS
0.20†
0.27*
⫺0.23*
⫺0.15‡
⫺0.17‡
⫺0.16‡
⫺0.16‡
⫺0.13‡
⫺0.17†
0.13‡
⫺0.14‡
NOTE: n ⫽ 237 for correlations involving pain tolerance, n ⫽ 238 for correlations involving pain intensity, n ⫽ 187 for correlations involving pain unpleasantness. Heat and cold pain tolerance and pressure pain unpleasantness are not shown in the table because of their nonsignificant associations with pain
coping strategies. Information seeking, problem solving, and externalizing are not shown in the table because of their nonsignificant associations with pain
responses.
*P ⬍ .001.
†P ⬍ .01.
‡P ⬍ .05.
ORIGINAL REPORT/Lu et al
713
Sequential Multiple Regression of Sex, Age, and PCQ Subscales on Laboratory Pain
Response Outcomes
Table 3.
Dependent Variables
Predictors (B)
(Independent Variables)
Step 1
Age
Sex
Step 1 - Adjusted R2
Step 2
Internalizing/catastrophizing
Seeking emotional support
Positive self-statements
Behavioral distraction
Step 2 - Adjusted R2
Critical values of ␣
Step1-2: R2 increments
PRESSURE PAIN
TOLERANCE
PRESSURE PAIN
INTENSITY
HEAT PAIN
INTENSITY
COLD PAIN
INTENSITY
HEAT PAIN
UNPLEASANTNESS
0.38*
0.20*
0.17*
⫺0.30*
⫺0.34*
⫺0.25*
0.09*
0.11*
0.05†
0.25*
0.23*
0.22†
COLD PAIN
UNPLEASANTNESS
0.23†
⫺0.26†
⫺0.19‡
0.16‡
0.20*
0.008
0.06‡
0.14*
0.012
0.08†
⫺0.19‡
0.18*
0.01
0.10*
0.05†
0.025
0.09†
⫺0.18‡
⫺0.21‡
0.10*
0.017
0.09‡
0.07‡
0.05
0.12†
NOTE: Only significant predictors are shown in the table. ␤ ⫽ standardized regression coefficient; Adjusted R2 ⫽ goodness of fit for overall regression model
taking into account of the number of independent variables; R2 increments ⫽ incremental contribution of the eight coping subscales to R2 in the total set of
independent variables (ie, the variance explained by these 8 coping subscales on pain above and beyond age and sex). For sex, girls and boys were coded as
0 and 1, respectively. Critical values of ␣ were determined following the Bonferroni-Holm step-down method. All 6 models had P values lower than the
critical values of ␣.
*P ⬍ .001.
†P ⬍ .01.
‡P ⬍ .05.
tions between the PCQ subscale scores and the
laboratory pain outcome variables. Pressure tolerance
was positively associated with behavioral distraction
and negatively associated with seeking emotional support. For pain intensity, internalizing/catastrophizing
was positively associated with pain intensity for all 3
tasks; positive self-statements was negatively associated with pressure and cold pain intensity; and cognitive
distraction was negatively associated with heat pain intensity. For pain unpleasantness, whereas internalizing/
catastrophizing was positively associated with heat and
cold pain unpleasantness, behavioral distraction was
negatively associated with pain unpleasantness for the
same 2 tasks; positive self-statements and cognitive distraction were both negatively associated with cold pain
unpleasantness. Information seeking, problem solving
and externalizing subscales were not significantly related to pain responses. Three of the pain outcomes (ie,
pain tolerance for heat and cold, or pain unpleasantness
for pressure) were not associated with any coping subscales, and thus were eliminated from multivariate analysis.
Multivariate Analysis: Coping Predictors
of Children’s Pain Tolerance, Intensity,
and Unpleasantness
Based on the bivariate findings, the 6 pain outcomes
(pressure tolerance, pain intensity for pressure, cold and
heat tasks, and pain unpleasantness for cold and heat
tasks) that showed significant correlations with the PCQ
subscale(s) were examined in separate regressions in
confirmatory analyses. Sequential linear regression was
used to predict each of the 6 pain outcomes from the 8
PCQ subscales simultaneously, controlling for age and
sex.
Pain Tolerance
Dependent variable pressure pain tolerance was regressed onto age and sex in Step 1, followed by the 8
coping subscales in Step 2. The PCQ subscales together
explained 6% of the variance in pressure pain tolerance
above and beyond age and sex (Table 3). Examination of
the individual PCQ subscales revealed that seeking emotional support predicted lower pressure pain tolerance
whereas behavioral distraction predicted higher pressure pain tolerance, controlling for the other coping subscales, age, and sex. The other coping subscales did not
significantly predict pressure pain tolerance. Older age
predicted higher pain tolerance, regardless of whether
or not coping strategies were taken into account. Consistent with our previous study, boys exhibited increased pressure pain tolerance than girls,20 but this
relationship disappeared after coping subscales were
taken into account.
Pain Intensity
Dependent variables pain intensity for all 3 pain tasks
were regressed onto age and sex in Step 1, and additional 8 coping subscales in Step 2. The R2 increments
from Step 1 to Step 2 were significant for all pain tasks.
The coping subscales together explained 8% to 10% of
the variance in pain intensity for these pain tasks above
714
Coping Predictors of Children’s Laboratory Pain
and beyond age and sex (Table 3). Internalizing/
catastrophizing predicted higher pain intensity across
all 3 tasks; positive self-statements predicted lower
pain intensity for the pressure and cold task, controlling for the other coping subscales, age, and sex. The
other coping subscales did not predict pain intensity.
Older age predicted lower pain intensity for the pressure and heat tasks regardless of whether coping strategies were taken into account. Sex was not a significant predictor of pain intensity for any of the pain
tasks.
Pain Unpleasantness
Dependent variables pain unpleasantness for the heat
and cold were regressed onto age and sex in Step 1 and
the 8 coping subscales in Step 2. The R2 increments from
Step 1 to Step 2 were significant for both tasks. The coping subscales together explained 9% to 12% of the variance in pain unpleasantness for the heat and cold tasks
above and beyond age and sex (Table 3). Internalizing/
catastrophizing predicted higher pain unpleasantness
during the cold task; positive self-statements predicted
lower pain unpleasantness during the cold task; and behavioral distraction predicted lower pain unpleasantness
during the heat task, controlling for the other coping
subscales, age, and sex. Older age predicted lower pain
unpleasantness during the heat task regardless of
whether coping strategies were taken into account; sex
did not significantly predict pain unpleasantness for the
pain tasks.
Discussion
We hypothesized 1) internalizing/catastrophizing and
seeking emotional support would predict increased pain
responses, and 2) positive self-statements and behavioral
and cognitive distraction would predict reduced pain responses (Fig 1). Our hypotheses were partially confirmed
in that internalizing/catastrophizing predicted higher
pain intensity across all 3 pain tasks (ie, cold, heat, and
pressure) and higher cold pain unpleasantness; seeking
emotional support was associated with lower pressure
pain tolerance; positive self-statements was associated
with lower pressure and cold pain intensity as well as
lower cold pain unpleasantness; and behavioral distraction was associated with higher pressure pain tolerance
and lower heat pain unpleasantness (Fig 2). The PCQ
subscales explained 6% to 12% of variance in pain responsivity above and beyond age and sex. Although the
amount of variance would appear to be small, the effect
sizes for the PCQ subscales ranged from 0.5 to 0.75 (Cohen’s d), corresponding to a medium to large effect according to Cohen’s guidelines (d ⫽ 0.5 to 0.8).2 It has
been suggested that different coping strategies may
serve either as risk factors for, or as protective factors
against, a poor pain outcome.35 The current findings
support the notion that internalizing/catastrophizing
and seeking emotional support are pain-prone/pain-risk
factors, and positive self-statements and distraction are
Figure 2. Associations between coping subscales and pain responsivity. Solid line indicates positive association between coping and pain responsivity and the dotted line indicates negative
association between coping and pain responsivity. Note that
increased pain responsivity is indicated by lower pain tolerance,
higher pain intensity and unpleasantness.
pain-protective factors within the context of acute laboratory-induced pain.
The communal Coping Model proposes that pain catastrophizers may engage in more intense pain expression
in order to solicit support or empathy from their social
environment,30,31 and solicitous responses from others
may serve to trigger, to maintain, or to reinforce the
more intense pain expression of catastrophizers.30 An
earlier study has shown that children displayed more intense pain expression to elicit parent support in the presence of parents during painful medical procedures.10
Our study demonstrated that even without parents’
presence, children with tendencies of seeking emotional
support were more likely to exhibit lower pain tolerance,
possibly due to habitual behavior of more intense pain
expression. However, the meaning of seeking emotional
support might depend on the nature of pain and the
social or familial context within which pain is experienced, as suggested by a study that revealed that seeking
emotional support predicted decreased distress in adolescents with chronic pain.5 The nature of pain might
also influence the links between pain responsivity and
other coping strategies, such as information seeking,
problem solving, and externalizing, which might be
more relevant when pain is chronic or lasting to allow
individuals enough time to engage in these coping strategies. Thus, the findings in our study might have more
relevance for children’s coping with acute pain in clinical
settings, such as procedural pain in primary care settings
or in the emergency department.
The association between positive self-statements coping and reduced pain was consistent with previous findings in a clinical sample.32 By reassuring oneself, “be
strong” “everything will be ok,” and “I can handle anything that happens,” those who engage in positive selfstatements might increase perceived control and thus
reduce anxiety and pain perception.12,16 In a previous
study, direct efforts to maintain control were found to
ORIGINAL REPORT/Lu et al
be the most frequently used coping strategy among
children during medical procedure.13 The use of positive self-statements may be a promising skill to be
taught to children who undergo painful medical procedures.
Behavioral distraction predicted lower pain responses
for pressure and heat pain, a finding consistent with a
meta-analysis on the effects of distraction on children’s
responses to painful medical procedures.19 The metaanalysis revealed that distraction had a modest effect on
reducing children’s distress behavior (eg, crying, whimpering, fighting) and a larger but more variable effect on
reducing children’s self-report of pain. In contrast, our
nonsignificant findings for cognitive distraction are inconsistent with the study by Piira et al,25 who found that
cognitive distraction was associated with greater cold
pressor tolerance. Piira et al’s study tested the partial
correlation between cognitive distraction and pain tolerance, controlling for pain threshold, whereas we
tested the independent effect of cognitive distraction,
controlling for the other PCQ subscales as well as age
and sex. In fact, our bivariate correlation results suggested that cognitive distraction was associated with
pain intensity and unpleasantness; however, the associations were not robust, and disappeared in the multivariate tests. The behavioral distraction items include
“do something fun” and “do something I enjoy,”
whereas the cognitive distraction items include “try to
forget it” and “ignore the situation.” Perhaps behavioral distraction with a focus on “fun” is more effective
than cognitive distraction with a focus on “ignoring or
avoiding.” Indeed, recent studies suggest that cartoon
TV and video games that are fun and enjoyable for
children may be promising and effective distraction
methods for painful medical procedures.3,4,9 Conversely, the PCQ cognitive distraction items are representative of an avoidant approach coping style associated with more pain-related disability in children with
recurrent abdominal pain.33
Older children exhibited greater pressure pain tolerance, lower pressure and heat pain intensity, and
lower heat pain unpleasantness, findings that are consistent with our previous study.20 Older children may
be better able than younger children to understand
that experimental pain is temporary, and thus less
threatening. Older children may have more experience
with more intensely painful events and understand
that much more painful events are possible than those
administered in this study. This experience/knowledge
may have influenced their ratings of the pain tasks on
a VAS scale. Older children may also have a larger
repertoire of coping strategies to assist them in tolerating the tasks longer than younger children and finding them less aversive.25 We found that older age was
related to increased use of problem solving and externalizing coping; however, these coping strategies did
not seem to be associated with laboratory pain responsivity.
Girls exhibited less pressure pain tolerance than boys,
and they also were more likely to use seeking emotional
715
support coping than boys, a finding consistent with a
recent study of adolescent chronic pain sufferers.18 Interestingly, seeking emotional support was also linked to
lower pressure tolerance. These findings point to the
possibility that seeking emotional support might play a
role in sex difference in pressure pain tolerance. Gender
role socialization results in sex-differentiated reinforcement and punishment for girls and boys with regard to
seeking social support when in pain,24 which may contribute to our present findings. A mediation analysis in a
future study, however, will shed additional light on this
issue.
Several caveats to the current findings should be mentioned. The present data are cross-sectional and, therefore, conclusions regarding causality cannot be inferred.
Administrating the PCQ before the laboratory tasks also
subjects the findings to an order effect. The PCQ could
potentially change participants’ reaction to pain because
they were alerted to ways of coping. Counterbalancing
the order of PCQ and pain tasks is recommended in future studies. Another limitation is that the PCQ measures
children’s ways of dealing with naturally-occurring pain
in a retrospective manner. Future studies should examine models incorporating trait measures of coping strategies to deal with chronic pain in real life in combination
with momentary coping strategies to deal with laboratory-induced pain as well as clinical acute pain situations.
We do not have a clear explanation for why certain PCQ
subscales were associated with certain pain responses for
1 type of pain stimulation but not others. Perhaps distinctive temporal, sensory, or affective characteristics of
the pain stimuli contribute to the lack of uniformity in
findings. Future studies of momentary coping strategies
might also help clarify why associations between coping
and pain response differed by types of pain stimulation.
Finally, while our analyses revealed statistically significant relationships between coping strategies and pain
responses in a controlled laboratory environment, it remains to be tested whether findings regarding coping in
the pain laboratory will generalize to coping in clinical
pain contexts.
In sum, our findings support the maladaptive role of
catastrophizing and seeking sympathy from others
when coping with acute pain, and the adaptive role of
distraction and positive self-statements. Distraction
has been extensively studied in interventions for clinical samples and shown to be effective at reducing
acute pain.6,19 However, few intervention studies have
focused on other coping strategies. The relationships
that were found between coping and laboratory pain
responses provide support for the potential use of laboratory pain tasks to teach new coping strategies for
acute pain, as has been done previously for children
with recurrent pain.8 Further studies are warranted to
examine whether interventions aimed at modifying
coping in the direction of reduced seeking of emotional support, reduced emotional avoidance and internalization/catastrophizing, and enhanced use of
716
positive self-statements may lead to reductions in children’s pain responses to acute pain stimuli such as
those that are encountered during routine medical
procedures.
References
1. Bell-Hoekstra IENG, Abu-Saad HH, Passchier J, Frederiks
CMA, Feron FJM, Knipschild P: Coping and Quality of Life in
relation to headache in Dutch schoolchildren. Eur J Pain
6:315, 2002
2. Cohen J: Statistical Power Analysis for the Behavioral Sciences. Hillsdale, NJ: Erlbaum; 1988
3. Cohen LL, Blount RL, Panopoulos G: Nurse Coaching and
cartoon distraction: An effective and practical intervention
to reduce child, parent, and nurse distress during immunizations. J Pediatr Psychol 22:355-370, 1997
4. Das D, Grimmer K, Sparnon A, McRae S, Thomas B: The
efficacy of playing a virtual reality game in modulating pain
for children with acute burn injuries: A randomized controlled trial [ISRCTN87413556]. BMC Pediatrics 5:1, 2005
5. Eccleston C, Crombez G, Scotford A, Clinch J, Connell H:
Adolescent chronic pain: Patterns and predictors of emotional distress in adolescents with chronic pain and their
parents. Pain 108:221, 2004
6. Fernandez E, Turk DC: The utility of cognitive coping
strategies for altering pain perception: a meta-analysis. Pain
38:123, 1989
7. Gil KM, Edens JL, Wilson JJ, Raezer LB, Kinney TR, Schultz
WH, Daeschner C: Coping strategies and laboratory pain in
children with sickle cell disease. Annu Behav Med 19:22-29,
1997
8. Gil KM, Wilson JJ, Edens JL, Workman E, Ready J, Sedway
J, Redding-Lallinger R, Daeschner CW: Cognitive coping
skills training in children with sickle cell disease pain. Int J
Behav Med 4:364-377, 1997
9. Gold JI, Kant AJ, Kim SH, Rizzo AS: Virtual anesthesia: The
use of virtual reality for pain distraction during acute medical interventions. Semin Anesth Perioperative Med Pain 24:
203, 2005
10. Gonzalez JC, Routh DK, Saab PG, Armstrong FD, Shifman L, Guerra E, Fawcett N: Effects of parent presence on
children’s reactions to injections: Behavioral, physiological,
and subjective aspects. J Pediatr Psychol 14:449-462, 1989
Coping Predictors of Children’s Laboratory Pain
Acknowledgments
We thank Norman Turk for his contribution to data
management.
16. Jensen MP, Turner JA, Romano JM, Karoly P: Coping
with chronic pain: A critical review of the literature. Pain
47:249, 1991
17. Keefe FJ, Lefebvre JC, Egert JR, Affleck G, Sullivan MJ,
Caldwell DS: The relationship of gender to pain, pain behavior, and disability in osteoarthritis patients: The role of catastrophizing. Pain 87:325, 2000
18. Keogh E, Eccleston C: Sex differences in adolescent
chronic pain and pain-related coping. Pain 123:275, 2006
19. Kleiber C, Harper DC: Effects of distraction on children’s
pain and distress during medical procedures: A meta-analysis. Nurs Res 48:44-49, 1999
20. Lu Q, Zeltzer LK, Tsao JCI, Kim SC, Turk N, Naliboff BD:
Heart rate mediation of sex differences in pain tolerance in
children. Pain 118:185, 2005
21. McGrath PA, Gillespie J: Pain assessment in children and
adolescents. In: Turk DC, Melzack R, eds. Handbook of pain
assessment, 2nd Edition. New York: Guilford; 2001:97-118
22. Meier PM, Berde CB, DiCanzio J, Zurakowski D, Sethna
NF: Quantitative assessment of cutaneous thermal and vibration sensation and thermal pain detection thresholds in
healthy children and adolescents. Muscle Nerve 24:13391345, 2001
23. Miller A, Barr RG, Young SN: The cold pressor test in
children: Methodological aspects and the analgesic effect of
intraoral sucrose. Pain 56:175, 1994
24. Myers CD, Tsao JCI, Glover DA, Kim SC, Turk N, Zeltzer
LK: Sex, gender, and age: Contributions to laboratory pain
responding in children and adolescents. J Pain 7:556, 2006
25. Piira T, Taplin JE, Goodenough B, von Baeyer CL: Cognitive-behavioural predictors of children’s tolerance of laboratory-induced pain: Implications for clinical assessment and
future directions. Behav Res Ther 40:571, 2002
26. Price DD: Central neural mechanisms that interrelate
sensory and affective dimensions of pain. Mol Interv 2:392403, 2002
27. Reid GJ, Gilbert CA, McGrath PJ: The Pain Coping Questionnaire: Preliminary validation. Pain 76:83, 1998
11. Gragg RA, Rapoff MA, Danovsky MB, Lindsley CB, Varni
JW, Waldron SA, Bernstein BH: Assessing chronic musculoskeletal pain associated with rheumatic disease: Further validation of the Pediatric Pain Questionnaire. J Pediatr Psychol
21:237-250, 1996
28. Spinhoven P, ter Kuile M, Kole-Snijders AMJ, Hutten
Mansfeld M, den Ouden D-J, Vlaeyen JWS: Catastrophizing
and internal pain control as mediators of outcome in the
multidisciplinary treatment of chronic low back pain. Eur J
Pain 8:211, 2004
12. Haythornthwaite JA, Menefee LA, Heinberg LJ, Clark
MR: Pain coping strategies predict perceived control over
pain. Pain 77:33, 1998
29. Sullivan MJL, Rodgers WM, Wilson PM, Bell GJ, Murray
TC, Fraser SN: An experimental investigation of the relation
between catastrophizing and activity intolerance. Pain 100:
47, 2002
13. Hodgins MJ, Lander J: Children’s coping with venipuncture. J Pain Sympt Manage 13:274, 1997
14. Hollingshead AB: Four-factor Index of Social Status.
New Haven, CT, Department of Sociology, Yale University,
1975
15. Holm S: A simple sequentially rejective multiple test procedure. Scand J Statist 6:65-70, 1979
30. Sullivan MJL, Martel MO, Tripp D, Savard A, Crombez G:
The relation between catastrophizing and the communication of pain experience. Pain 122:282, 2006
31. Sullivan MJL, Thorn B, Haythornthwaite JA, Keefe F,
Martin M, Bradley LA, Lefebvre JC: Theoretical perspectives
on the relation between catastrophizing and pain. Clin J
Pain 17:52-64, 2001
ORIGINAL REPORT/Lu et al
32. Thastum M, Herlin T, Zachariae R: Relationship of paincoping strategies and pain-specific beliefs to pain experience in children with juvenile idiopathic arthritis. Arthritis
Care Res 53:178-184, 2005
33. Thomsen AH, Compas BE, Colletti RB, Stanger C, Boyer
MC, Konik BS: Parent reports of coping and stress responses
in children with recurrent abdominal pain. J Pediatr Psychol
27:215-226, 2002
34. Tsao JCI, Myers CD, Craske MG, Bursch B, Kim SC, Zeltzer
LK: Role of anticipatory anxiety and anxiety sensitivity in
717
children’s and adolescents’ laboratory pain responses.
J Pediatr Psychol 29:379-388, 2004
35. Varni JW, Waldron SA, Gragg RA, Rapoff MA, Bernstein
BH, Lindsley CB, Newcomb MD: Development of the Waldron/Varni Pediatric Pain Coping Inventory. Pain 67:141,
1996
36. Walker LS, Smith CA, Garber J, Claar RL: Testing a model
of pain appraisal and coping in children with chronic abdominal pain. Health Psychol 24:364, 2005