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1
EFFECTS OF COPING STATEMENTS ON EXPERIMENTAL PAIN IN CHRONIC PAIN PATIENTS
By
DANIELA RODITI
A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
2010
2
© 2010 Daniela Roditi
3
To everyone who has inspired, encouraged, and supported me throughout my lifetime in all personal, academic, and professional achievements, making this milestone
possible
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ACKNOWLEDGMENTS
I am greatly thankful to my mentor, Dr. Michael E. Robinson, for his continuing and
unwavering support and guidance throughout the development of this project from the
beginning to the end. Additionally, I would like to recognize as the members of my
supervisory committee Dr. Stephen Boggs, Dr. Glenn Ashkanazi, and Dr. Russell
Bauer. Lastly, I would like to recognize my family, friends, and colleagues for their
support throughout this project.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS ...............................................................................................................4
LIST OF TABLES ..........................................................................................................................7
LIST OF FIGURES........................................................................................................................8
ABSTRACT ....................................................................................................................................9
CHAPTER
1 INTRODUCTION .................................................................................................................11
Coping 11 Catastrophizing .............................................................................................................11 Positive Coping Self-Statements ...............................................................................12
Response Expectancies .....................................................................................................12 Previous Coping Research ................................................................................................13 Current Study .......................................................................................................................14
2 MATERIALS AND METHODS ...........................................................................................15
Procedure ..............................................................................................................................15 Participants ...........................................................................................................................16 Apparatuses..........................................................................................................................17 Measures ..............................................................................................................................17
Demographics ...............................................................................................................17 Coping Statements .......................................................................................................18 Pain Threshold ..............................................................................................................18 Pain Tolerance ..............................................................................................................18 Pain Endurance .............................................................................................................18 Pain Intensity .................................................................................................................19
3 RESULTS ..............................................................................................................................24
Descriptive Analyses ...........................................................................................................24 First Hypothesis ....................................................................................................................24 Second Hypothesis ..............................................................................................................26
4 DISCUSSION .......................................................................................................................30
Clinical Implications .............................................................................................................34 Methodological Limitations and Future Research Directions .......................................35
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5 SUMMARY ............................................................................................................................38
LIST OF REFERENCES ............................................................................................................40
BIOGRAPHICAL SKETCH ........................................................................................................44
7
LIST OF TABLES
Table page 2-1 Demographic variables of total sample (N = 58) ................................................. 19
2-2 List of Catastrophizing Self-Statements .............................................................. 20
2-3 List of Positive Coping Self-Statements .............................................................. 21
3-1 ANOVA results of comparison between two coping groups ............................... 27
3-2 Mean PSR and Peak Pain Intensity Measurements of Catastrophizing and Positive Self-Statement (PSS) Groups ............................................................... 29
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LIST OF FIGURES
Figure page 2-1 Experimental Procedure Flowchart ..................................................................... 22
2-2 Cold Pressor Apparatus. Taken in 2010 in the Center for Pain Research laboratory ........................................................................................................... 23
3-1 Effects of coping manipulation on PSR. ............................................................. 28
9
Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science
EFFECTS OF COPING STATEMENTS IN EXPERIMENTAL PAIN IN CHRONIC PAIN
PATIENTS
By
Daniela Roditi
May 2010 Chair: Michael E. Robinson Major: Psychology
Catastrophizing has been well-established in the literature as a cognitive mediator
in the pain experience and a predictor of the pain experience as indicated by
heightened pain sensations and lower thresholds for pain for catastrophizers. Relatively
few studies have investigated the direct relationship between positive cognitions and
pain. The present study measured the effects of response expectancies
(catastrophizing self-statements and positive coping self-statements) on cold pressor-
induced pain.
Participants were 58 adult chronic pain patients with current facial pain. It was
hypothesized that catastrophizing would lead to a decrease in pain endurance whereas
positive coping would lead to an increase in pain endurance. It was also hypothesized
that catastrophizing would lead to an increase in peak pain intensity whereas positive
coping would lead to a decrease in peak pain intensity.
Participants signed a consent form explaining possible risks associated with the
experiment. The University of Florida Institutional Review Board approved the
procedures and protocols of the study. A cold pressor apparatus was used to induce
pain in participants. A pressure sensitive bladder/transducer was used to measure pain
10
intensity. Pain endurance was determined by calculating the difference between
tolerance and threshold. At pretest, participants submerged their non-dominant hand in
the cold pressor. Pain endurance and peak pain intensity measurements were
recorded. Participants underwent random assignment to a catastrophizing group or a
positive coping group. Participants chose one coping statement from a given list to use
as a coping strategy during the test phase.
ANCOVA results indicated a significant effect of coping on pain endurance after
controlling for pretest pain endurance, F(1, 36) = 5.525, p < .05. Manipulation of coping
explained 13.3% of the variance in test phase pain endurance. On average, participants
employing catastrophizing statements as a coping strategy experienced significantly
lower pain endurance (M = 35.53, SD = 39.71) compared to participants employing
positive coping statements (M = 73.70, SD = 86.14). However, the type of coping
statement (group assignment) used had no significant influence on peak pain intensity
measurements.
Most previous work showing a coping-pain relationship cannot confirm causality of
the relationship. The results of this research show that manipulation of coping causes
changes in pain behavior. This provides a mechanism for considering how response
expectancies mediate pain endurance in clinical settings, ultimately leading to more
effective treatment options.
11
CHAPTER 1 INTRODUCTION
Coping
Lazarus and Folkman (1984) best defined coping as an active effort to manage or
control a perceived stressor. Nevertheless, there is no universally agreed upon
operational definition of what constitutes a coping strategy or a universally agreed upon
way to classify the several different coping strategies that have been identified. A
frequently used classification system within the context of chronic pain centers around
the dichotomy of active versus passive coping. Passive coping includes those strategies
in which one surrenders control or withdraws from the pain (Van Damme, Crombez, &
Eccleston, 2008). Conversely, active coping strategies are those involving an attempt to
control or manage the pain or to persevere regardless of the experienced pain (Van
Damme, et al., 2008). The present study will focus specifically on catastrophizing and
positive coping self-statements which are two types of coping strategies representing
passive coping and active coping, respectively.
Catastrophizing
Catastrophizing is the tendency to exaggerate the negative outcomes of a
situation (Turner, Jensen, & Romano, 2000). More specifically, pain catastrophizing is
characterized by pessimistic cognitions leading to exaggerations and negative
expectations of the pain experience such as heightened pain perceptions. It involves
elements of helplessness and pessimism as captured by the catastrophizing subscale
of the Coping Strategies Questionnaire (Rosenstiel & Keefe, 1983). Within the
aforementioned classification system catastrophizing is a type of passive coping (Van
Damme, et al., 2008). Catastrophizing has been well-established in the literature as a
12
cognitive mediator in the pain experience and a predictor of the pain experience as
indicated by heightened pain sensations and lower thresholds for pain for
catastrophizers (George & Hirsch, 2008; Keefe, et al., 2000; Sullivan, Rodgers, &
Kirsch, 2001; Sullivan, Thorn, Rodgers, & Ward, 2004). Research also suggests a
positive correlation between catastrophizing and depression exists in chronic pain
patients (Lee, Wu, Lee, Cheing, & Chan, 2008; Lopez-Lopez, Montorio, Izal, & Velasco,
2008; Sullivan & D'Eon, 1990; Turner, et al., 2000). Despite the wealth of literature
regarding catastrophizing and pain, most research has been correlational supporting the
notion of an antecedent relationship but not a causal one (Roth, Lowery, & Hamill, 2004;
Severeijns, Vlaeyen, van den Hout, & Weber, 2001; Sullivan, et al., 2001; Sullivan, et
al., 2004).
Positive Coping Self-Statements
Positive coping self-statements are those which encourage the individual to persist
despite pain or to reassess the situation in a more positive light. Relatively few studies
have investigated the direct relationship between positive cognitions and pain. Some
research has found that higher use of coping self-statements was predictive of higher
perceptions of control over pain (Haythornthwaite, Menefee, Heinberg, & Clark, 1998).
Moreover, it has been suggested that positive coping self-statements interact with level
of pain intensity (Jensen & Karoly, 1991; Jensen, Turner, & Romano, 1992). There is
some indication that positive coping self-statements are correlated with fewer
depressive symptoms (Walker, Smith, Garber, & Claar, 2005).
Response Expectancies
Response expectancies have been defined in the literature as non-volitional
responses to events (Kirsch, 1985). These are differentiated from Rotter’s social
13
learning theory concept of outcome expectancies by virtue of being automatic rather
than meditated responses as is the case with outcome expectancies (Kirsch, 1985;
Rotter, 1954). In addition, response expectancies have been typically differentiated by
their virtue of being self-confirming. It has been suggested that response expectancies
may be a mechanism by which psychotherapy produces change for the patient (Milling,
Reardon, & Carosella, 2006). In particular, Milling et al. posit that response
expectancies may produce analgesia in pain treatments by creating a cognitive set in
which the individual being treated comes to expect reductions in pain (2006). Therefore,
we propose that response expectancies and voluntary cognitive efforts need not be
mutually exclusive concepts. It seems as though the cognitive set believed to be
responsible for analgesic relief in pain treatments exemplifies this proposition. If a
cognitive set is established, it is no longer an automatic, non-volitional response but
rather a deliberate, effortful process. Furthermore, if theory regarding response
expectancies is expanded to include both non-volitional and volitional expectations, then
we hold that these can be manipulated by altering existing or creating new cognitive
sets in which a person expects either diminished pain or increased pain. Therefore, a
possible mechanism by which expectancies can be manipulated is via alteration of
coping self-statements. Positive self-statements can be induced in participants to
produce a change of expectations of a more favorable outcome. Likewise,
catastrophizing statements may be a mechanism by which expectancies can be
negatively manipulated, resulting in pessimistic expectations for a worse outcome.
Previous Coping Research
Previous research found that preexisting catastrophizing predicted higher pain
intensity in an experimental task on children and adolescents, whereas preexisting
14
positive coping self-statements predicted lower pain intensity (Lu, Tsao, Myers, Kim, &
Zeltzer, 2007). Research by Severeijns et al. found that, although catastrophizing was
successfully manipulated in participants in the experimental group condition, it did not
moderate the pain experience as neither pain expectancy levels, nor experienced peak
pain intensity levels, nor pain tolerance differed significantly from those of participants in
the control group condition (2005). It is important to further investigate the relationship
between catastrophizing and pain as well as positive coping and pain using an
experimental research design in order to infer a causal relationship between cognitions
and pain experience.
Current Study
The present study aimed to build on the current literature on catastrophizing and
pain and positive coping and pain from an experimental perspective by directly
manipulating the constructs in a sample of adult chronic pain patients. Most previous
studies have not directly manipulated catastrophizing or positive coping and findings
from studies that have done so are not consistent with the hypothesized theory (Lu, et
al., 2007; Severeijns, et al., 2005). The primary aims were to evaluate the effects of
catastrophizing and positive coping on Pain Sensitivity Range (PSR) and peak pain
intensity measurements during experimentally induced pain using the cold pressor task.
It was hypothesized that catastrophizing would lead to a decrease in pain endurance as
measured by PSR whereas positive coping would lead to an increase in pain endurance
as measured by PSR. It was also hypothesized that catastrophizing would lead to an
increase in peak pain intensity measurements whereas positive coping would lead to a
decrease in peak pain intensity measurements.
15
CHAPTER 2 MATERIALS AND METHODS
Procedure
Participants signed a consent form explaining possible risks associated with the
experiment and were all assured that they could withdraw from the study at any time
without negative consequences if they chose to. The University of Florida Institutional
Review Board approved the procedures and protocols of the study.
In the pretest, all participants submerged their non-dominant hand, palm facing
down, in the cold pressor apparatus. Participants were instructed to say “pain” when
they first experienced pain (to measure pain threshold) and to keep their hand
submerged in the cold water as long as possible (to measure pain tolerance). Pain
sensitivity ranges were subsequently determined for each participant by calculating the
difference between pain tolerance time and pain threshold time. Pain intensity
measurements were recorded as indicated by the pressure sensitive
bladder/transducer. Participants were instructed to press the pressure sensitive
bladder/transducer to indicate the level of pain intensity throughout the duration of the
cold pressor task. Only peak pain intensity measurements were used for data analyses.
Participants were randomly assigned to one of two groups: catastrophizing self-
statements or positive coping self-statements. Participants in each group were asked to
rehearse statements from the designated lists and instructed to choose one statement,
repeated aloud, to use as a coping strategy for the duration of the cold pressor task
during the test phase.
In the test phase participants repeated the cold pressor task following the same
protocol as the pretest with the addition of the chosen coping strategy repeated aloud.
16
Pain threshold and pain tolerance were reassessed. New pain intensity measurements
were recorded as indicated by the pressure sensitive bladder/transducer.
Upon completion of the test phase, participants were debriefed concerning the
nature of the study. All participants received information regarding appropriate coping
strategies in the management of chronic pain. Figure 2-1 shows a flowchart diagram of
the experimental procedures.
Participants
Adult chronic pain patients (N = 58) with current facial pain stemming from
temporomandibular disorders (TMD) were recruited from the Parker Mahan Facial Pain
Center at the University of Florida. Eligibility criteria excluded all those with pain
duration shorter than six months, those with pain related to malignant process, those
with upper extremity pain, and those with history of severe cardiovascular disease. The
mean age of the sample was 39.30 (range 18-65, SD = 11.68) years. Forty-nine
participants were female and nine were male. Primary diagnoses included myofascial
pain syndrome, bruxism, noxious occlusion, degenerative arthritis, fibromyalgia, and
disk displacement. Participants had a mean education level of 13.88 years (SD = 1.90).
The mean duration of pain was 97.69 (SD = 95.74) months. The majority of participants
were married (38), 15 were single, 4 were divorced, and 1 was widowed. The sample
was predominantly Caucasian (56); the remaining participants were African American
(2). Thirty-seven participants were currently employed; the remaining twenty-one were
currently unemployed. Table 2-1 provides demographic information for the total sample
of facial pain patients.
17
Apparatuses
A cold pressor apparatus was used to induce pain in participants. It consisted of a
2.5 cubic foot thermal cooler divided by a fitted screen. One side of the apparatus
contained cold water whereas the other side contained ice. Water circulated from one
side to the other via a dc bilge pump allowing for water to remain at a constant
temperature range of 1-3 degrees Celsius. The 1-3 degree variation in the water
temperature in the cold pressor is within standard parameters for a cold pressor task.
Figure 2-2 displays a picture of a cold pressor apparatus used to induce pain in
participants.
A pressure sensitive bladder/transducer was used to measure individual ratings of
pain intensity in response to the cold pressor apparatus. The pressure sensitive bladder
consisted of a blood pressure monitor inflation device linked to a computer via a
pressure transducer (an HC11 microprocessor) allowing for analog to digital conversion.
The device required 20 lbs. of force to reach a maximum voltage of 5 volts. No subjects
were able to maximize this pressure/voltage, thus eliminating the possible confound of
ceiling effects. The resolution of the processor allowed for measurement sensitivity to
increments of .01 volts.
Measures
Demographics
A self-report questionnaire was used to gather demographic information from all
participants. Questions inquired about participants’ age, sex, race/ethnicity, marital
status, years of education attained, employment status, pain duration, and primary pain
diagnosis.
18
Coping Statements
A list of catastrophizing statements was derived from the Coping Strategies
Questionnaire CSQ-CAT subscale (Rosenstiel & Keefe, 1983) and a list of positive
coping statements was created by using statements opposite of the catastrophizing
statements generated. Table 2-2 reports the list of catastrophizing self-statements given
to participants in the negative coping group. Table 2-3 reports the list of positive coping
self-statements given to participants in the positive coping group.
Pain Threshold
Pain threshold was determined by the amount of time elapsed from initial
immersion of hand into the cold pressor apparatus to the moment participants verbally
indicated they felt pain.
Pain Tolerance
Pain tolerance was determined by the amount of time elapsed from initial
immersion of hand into the cold pressor apparatus to the moment participants removed
their hand from the cold pressor. A limit of 300 seconds was set for tolerance at which
point participants were asked to remove their hand due to risk of injury. A total of ten
participants reached the tolerance limit at one or both of the testing phases.
Pain Endurance
Pain sensitivity ranges were determined for each participant by calculating the
difference between tolerance and threshold. PSR was used as a measure of pain
endurance and has been found to be a more stable measure of pain than pain tolerance
(Wolff, 1986). Thus, this was selected as the dependent variable to preclude bias
derived from pre-pain perception often inherent in threshold and tolerance ratings.
19
Pain Intensity
Peak pain intensity was determined by the selecting the highest voltage pain
intensity measurement as indicated by the pressure sensitive bladder/transducer.
Table 2-1. Demographic variables of total sample (N = 58) Demographic variables n % years or months Gender
Males 9 15.52% Females 49 84.48%
Mean Age (in years) 39.30 (SD = 11.68) Ethnicity
Caucasian 56 96.55% African American 2 3.45%
Marital Status Married 38 65.52% Divorced 4 6.90% Widowed 1 1.72% Single 15 25.86%
Mean Years of Education 13.88 (SD = 1.90) Employment
Employed 37 63.79% Unemployed 21 36.21%
Mean Pain Duration (in months) 97.69 (SD = 95.74)
20
Table 2-2. List of Catastrophizing Self-Statements 7 Catastrophizing Statements This is terrible. This is never going to get better. This is overwhelming. I cannot control the pain. This is worse than I thought. I can’t stand it anymore. I feel like I can’t go on.
21
Table 2-3. List of Positive Coping Self-Statements 7 Positive Coping Statements One step at a time, I can handle it. I just have to remain focused on the positives. It will be over soon. I can control the pain. It won't last much longer. This isn't as bad as I thought. No matter how bad it gets, I can do it.
22
Informed Consent Signed
Pretest: Cold Pressor Task
Random Group Assignment
PSR calculated and recorded
Catastrophizing Self-Statements Group Positive Self-Statements Group
Test phase: Cold Pressor Task using selected Coping strategy
Test phase: Cold Pressor Task using selected Coping strategy
PSR Calculated and recorded Peak Pain Intensity recorded
PSR Calculated and recorded Peak Pain Intensity recorded
Debriefing
Debriefing
Rehearsal of Statements
Rehearsal of Statements
Figure 2-1. Experimental Procedure Flowchart
23
Figure 2-2. Cold Pressor Apparatus. Taken in 2010 in the Center for Pain Research laboratory
24
CHAPTER 3 RESULTS
The statistical analyses conducted to evaluate the hypotheses for this research
project were analyzed using the Statistical Package for Social Sciences (SPSS). An
alpha level of .05 was used for all statistical tests. Variables were examined on a list-
wise basis for each hypothesis; thus, excluding from the analyses participants for whom
data from variables of interest were missing.
Descriptive Analyses
A comparison of the catastrophizing self-statements group and the positive coping
self-statements group was conducted to assess for any significant differences among
demographic variables between the two groups. Levene’s test results were non-
significant for the variables examined: age, race, number of years of education attained,
employment status, duration of pain, and pretest pain endurance; thus, we failed to
reject the assumption of homogeneity of variances. Results of a one-way independent
ANOVA revealed that on average, participants in the catastrophizing self-statements
group did not differ significantly from participants in the positive self-statements group
along the dimensions of age, race, number of years of education attained, employment
status, duration of pain, or pretest pain endurance. Table 3-1 reports Levene’s statistics,
F statistics, means, standard deviations, and probability values for the variables
analyzed.
First Hypothesis- Pain Endurance
In the analyses of our first hypothesis, of the initial 58 participants, only the data
from 39 participants were used. Data from the remaining participants were excluded as
PSRs could not be calculated because participants either reached the maximum
25
tolerance time of 300 seconds or did not indicate “pain” and, thus, threshold time could
not be determined. Among those participants excluded from the analyses, 9 were
assigned to the catastrophizing group and 10 to the positive self-statements group.
Between-group analyses revealed participants did not differ among demographic
variables (see Table 3-1).
On average, participants employing catastrophizing statements as a coping
strategy experienced a 20.05 second decreased PSR (pretest M = 55.58, SD = 72.45,
test phase M = 35.53, SD = 39.71) and participants employing positive coping self-
statements showed a 12.15 second increase in PSR (pretest M = 61.55, SD = 87.32,
test phase M = 73.70, SD = 86.14), as shown in Figure 3-1. To test the effect of coping
statement manipulation an ANCOVA with test phase PSR as the dependent variable
and pretest PSR as the covariate was performed. Results indicated that after controlling
for pre-manipulation PSR, post-manipulation PSR differed between the two coping
statement groups. Results indicated a significant effect of coping on PSR after
controlling for pretest PSR, F(1, 36) = 5.525, p < .05. Manipulation of coping explained
13.3% of the variance in test phase PSR (see Table 3-2).
It should be noted that our findings did not reveal any within-group effects. Paired
samples t-tests indicated that although the positive coping self-statements and the
catastrophizing self-statements groups differed significantly from one another at test
phase (between-groups effect), each group’s endurance at test phase was not
significantly different from the mean at pretest, t(19) = -1.05, p = .305, d = .33 and t(18)
= 1.54, p = .140, d = .59, respectively. Therefore, the post-intervention difference
represents the combination of smaller within-group endurance effects in opposite
26
directions (as hypothesized). The absence of statistically significant within-group
differences is likely a function of an underpowered sample size. Nevertheless, d = .33
and d = .59 represent small to medium and medium effect sizes, and suggest these
findings might represent meaningful relationships. Of note, there were no significant
between-group PSR differences at pretest, t(45) = -.065, p = .948.
Second Hypothesis- Peak Pain Intensity
In the analysis of our second hypothesis, of the initial 58 participants, only the data
from 50 participants were used. Data from the remaining participants were excluded as
no pain intensity measurements were recorded for them.
On average, participants employing catastrophizing statements as a coping
strategy did not experience a significant change in test phase peak pain intensity
(pretest M = 1.81, SD = .20, test phase M = 1.86, SD = .29) compared to participants
employing positive coping self-statements (pretest M = 1.83, SD = .18, M = 1.83, SD =
.19). To test the effect of coping statement manipulation an ANCOVA with test phase
peak pain intensity measurement as the dependent variable and pretest peak pain
intensity measurement as the covariate was performed. Results indicated that after
controlling for pre-manipulation peak pain intensity measurement, post-manipulation
peak pain intensity measurement did not differ significantly between the two coping
statement groups. Results indicated a non-significant effect of coping on peak pain
intensity measurement after controlling for pretest peak pain intensity measurement,
F(1, 47) = .705, p > .05 (see Table 3-2).
27
Table 3-1. ANOVA results of comparison between two coping groups
Demographic Variables n Levene's statistic p
F statistic p Mean SD
Age 2.36 0.13 0.72 0.79 Positive Coping 29 38.93 10.69
Catastrophizing 29 39.76 12.77
Race 1.72 0.20 0.40 0.53 Positive Coping 29 1.03 0.19
Catastrophizing 29 1.10 0.56 Years of Education attained 0.00 0.96 0.01 0.95
Positive Coping 29 13.86 1.77
Catastrophizing 29 13.90 2.04
Employment Status 0.29 0.60 0.07 0.79 Positive Coping 29 0.62 0.49
Catastrophizing 29 0.66 0.48 Pain Duration (in months) 0.01 0.91 1.43 0.24
Positive Coping 29 82.69 105.38
Catastrophizing 29 112.69 84.20
Pretest PSR (in seconds) 0.23 0.63 0.00 0.95 Positive Coping 23 56.91 82.14
Catastrophizing 24 58.46 79.63
28
Figure 3-1. Effects of coping manipulation on PSR.
Note: Mean pain sensitivity ranges in seconds. Error bars represent standard error.
29
Table 3-2. Mean PSR and Peak Pain Intensity Measurements of Catastrophizing and Positive Self-Statement (PSS) Groups
________________________________________________________________________ Mean Standard deviation
___________________ ___________________ Group Pretest Test phase Pretest Test phase ________________________________________________________________________ PSR (n = 39) Catastrophizing 55.58 35.53* 72.45 39.71 PSS 61.55 73.70* 87.32 86.14
________________________________________________________________________
Peak Pain Intensity Measurement (n = 50) Catastrophizing 1.81 1.86 .20 .29 PSS 1.83 1.83 .18 .19 ________________________________________________________________________ Note. Maximum PSR = 300 seconds. Maximum Peak Pain Intensity = 5 volts. Means marked with an asterisk differ at p < .05. ANCOVA results indicated that after controlling for pre-manipulation PSR, post-manipulation PSR differed between the two coping statement groups. Results indicated a significant effect of coping on PSR after controlling for pretest PSR, F(1, 36) = 5.525, p < .05. Manipulation of coping explained 13.3% of the variance in test phase PSR.
30
CHAPTER 4 DISCUSSION
By manipulating the use of coping strategies we were able to evaluate the effects
of catastrophizing and positive coping self-statements on pain endurance (PSR) and
peak pain intensity during experimentally induced pain. As indicated in the results
section, the catastrophizing and positive coping self-statements groups differed post-
intervention. Examination of Figure 3-1 and of the within-group effect sizes suggests
that the post-interventions differences resulted from smaller non-significant within-
groups effects in opposite directions (as hypothesized). The direction of these findings
supports extant literature stating catastrophizing is a mediator in the pain experience
(Edwards, Haythornthwaite, Sullivan, & Fillingim, 2004; Keefe, et al., 2000; Sullivan, et
al., 2001; Sullivan, et al., 2004; Turner, Holtzman, & Mancl, 2007). Furthermore, using
random assignment and the experimental manipulation of coping statements, results
support a causal relationship between coping self-statements and pain perception.
Specific evidence suggesting catastrophizing uniquely contributes to decreases in pain
endurance is inconclusive. Although several research findings have not found
catastrophizing to uniquely affect pain tolerance time there are some research findings
supporting this notion (France, et al., 2004). It is possible that when several mediators
and predictors of pain are evaluated, shared variance (e.g. negative affect, fear of pain)
eclipses the unique contribution of catastrophizing (Hirsh, George, Bialosky, &
Robinson, 2008; Hirsh, George, Riley, & Robinson, 2007). More work on the unique
contributions of negative and positive coping, and negative mood measures is
warranted.
31
Additionally, it is important to highlight that although our results are not applicable
to a direct numerical translation to changes in clinical pain endurance, the magnitude of
raw change produced by our manipulation is substantial. Specifically, participants in the
catastrophizing self-statements group experienced a 56.43% decrease in endurance
(20.05 seconds) and those in the positive self-statements group experienced a 16.49%
increased endurance (12.15 seconds). We propose that such a change would be of
great clinical significance if similar changes were to occur in a clinical setting.
This study adds to the body of literature by furthering the hypothesis of an
antecedent relationship between catastrophizing and decreased pain endurance and
positive coping. Additionally, it adds to the current body of literature by demonstrating
the effects (changes in pain endurance) of experimental manipulation of coping
strategies. These findings lend support for this being a potential causal association
between coping strategy and pain endurance. It is possible that the use of PSR as a
measure of pain endurance is a viable explanation for why we successfully found
effects of coping on the pain experience in light of the divergent findings in the extant
literature regarding pain tolerance time (France, et al., 2004; Lu, et al., 2007;
Severeijns, et al., 2005). Whereas other measures of tolerance do not measure the time
period of experienced pain and instead measure the time point at which pain becomes
unbearable, our measure of endurance includes only the time period during which one
is coping with experienced pain by excluding the time period prior to threshold; a subtle
but potentially important difference. This explanation would suggest that effects of pain
endurance ought to be considered in future research alongside the more commonly
used measures of pain threshold and pain tolerance.
32
A second aim was to examine the effects of catastrophizing and positive coping on
peak pain intensity measurements. Results did not support our hypothesis. The
manipulation of coping strategies did not affect peak pain intensity measurements
signifying participants did not experience heightened pain upon employing
catastrophizing coping strategies nor did they experience a decrease in pain upon
employing positive self-statements as coping strategies. Interestingly, although our
findings did not support such a relationship, the positive relationship between
catastrophizing and heightened pain sensations is widely supported in the extant
literature (George & Hirsch, 2008; Keefe, et al., 2000; Picavet, Vlaeyen, & Schouten,
2002; Sullivan, et al., 2001; Sullivan, et al., 2004). Taken together these findings
suggest that the manipulation of coping strategies led participants in our sample to
endure pain differentially despite the fact that they were experiencing the same peak
pain intensity as they were prior to the manipulation of coping. Interestingly, this lends
support for the theory that expectations, rather than demand characteristics, may be the
underlying mechanism responsible for the changes in pain endurance. If, indeed,
demand characteristics induced by the statements were responsible for the changes
observed at test phase then both, pain endurance and pain intensity measurements,
should have changed. Instead our results show that the only change was participants’
willingness to endure pain regardless of experiencing the same peak intensity of pain.
Nevertheless, it is a possibility that demand characteristics motivated participants in the
positive coping self-statements group to endure pain for a longer period of time and
participants in the catastrophizing self-statements group for a shorter duration of time.
Participants, therefore, may have simply been behaving in a manner consistent with the
33
way they believed the experimenter expected them to behave. It remains to be
determined if the failure to affect peak pain intensity is a function of the manner in which
peak pain intensity was obtained in this study, or if cognitive strategies more strongly
operate on more tonic pain, or the endurance of pain. The pressure sensitive
bladder/transducer we employed allowed for precise .5 second resolution of pain
intensity, and unlike other pain intensity measurements, it did not ask participants to rely
on retrospective assessment or cumulative averages of their pain in order to rate it.
Therefore, it is possible that the absence of a cognitive component in measurement
unique to pain may partially account for the lack of coping manipulation effects on peak
pain intensity.
Response expectancies have been found to have a significant concordant
influence on the pain experience (Baker & Kirsch, 1991; Sullivan, et al., 2001). There is
support for the theory that response expectancies partially mediate the relation between
catastrophizing and the pain experience and it is likely that response expectancies may
also mediate the relation between optimism and the pain experience (Sullivan, et al.,
2001). Although there are mixed findings in the literature, optimism has been found to
partially mediate pain intensity in cancer patients and in laboratory induced pain
(Geers, Wellman, Helfer, Fowler, & France, 2008). Recent literature reveals that the
placebo effect is an example of how expectancies may influence and determine the pain
experience (Pollo, et al., 2001; Vase, Robinson, Verne, & Price, 2003). Similarly, we
assumed that presenting participants with self-statements of poor pain coping
(catastrophizing) or increased pain coping (positive expectations) would generate
underlying pain expectations responsible for the changes in PSR. Consistent with the
34
observed effect of catastrophizing and pain in this study, negative expectations have
been found to be unique contributors to a heightened pain experience (Montgomery &
Bovbjerg, 2004; Sullivan, et al., 2001). Unfortunately, research exploring positive
expectations and their relationship to pain experience is scarce in comparison and
findings are often inconclusive. Research has tended to focus predominately on
negative contributors to the pain experience almost to the exclusion of positive
protective factors in the pain experience. Therefore, although there is some evidence
regarding the association between negative and positive expectations, pessimism and
optimism, and decreased pain, additional research in this area is warranted.
Clinical Implications
As aforementioned our results are not applicable to a direct translation to changes
in clinical pain endurance; nevertheless, the changes produced by our manipulation
reflect changes commonly obtained through efficacious clinical interventions. While
cognitive-behavioral therapy (CBT) interventions may vary substantially, CBT
interventions generally include common components such as psychoeducation,
relaxation techniques, training in effective coping strategies, and cognitive restructuring
specifically targeting dysfunctional/unrealistic thoughts. In the context of chronic pain
interventions, CBT has been found to be efficacious (Morley, Eccleston, & Williams,
1999) although the exact components that lead to successful outcomes have yet to be
discerned. It has been suggested that, perhaps, the improvement of self-efficacy may
be one of the principal common factors driving successful outcomes (Turk, Swanson, &
Tunks, 2008). Therefore, a possible mechanism by which self-efficacy can be increased
is through the attainment of favorable expectations (i.e. positive self-statements) and
the reduction of pessimistic expectations (i.e. catastrophizing self-statements).
35
Research in a sample of chronic headache sufferers revealed that CBT interventions
aimed at reducing catastrophizing and adopting cognitive coping strategies (positive
self-statements regarding ability to manage headaches) alongside behavioral coping
strategies revealed that this intervention led to significant improvements headache
experience marked by reductions in the headache frequency and peak intensity, the
reduction of catastrophizing, and significant increases in headache management self-
efficacy as measured by self-report assessments (Thorn, et al., 2007). Changes were
maintained at post-treatment and 12 month follow-up (Thorn, et al., 2007). Our findings
coupled with clinical intervention findings suggest that pain-relief expectations are highly
amenable to change and are responsive to pain-specific cognitive-behavioral treatments
in select patient populations.
Methodological Limitations and Future Research Directions
The generalizability of the findings in this study is limited to our sample. A design
limitation includes the absence of a neutral control group as the pre-post design is
subject to pretest sensitization. The absence of a specific manipulation check prevents
us from conclusively knowing if our manipulation of coping was responsible for the
changes in pain endurance. However, it should be taken into account that participants
were instructed to verbalize and repeat aloud the coping strategy they selected
throughout the test phase therefore ensuring participants were at least partially
cognitively engaging in the particular strategy (via awareness and verbalization). As
previous findings in CBT research suggest, it is a plausible explanation that participants’
expectations for pain relief or ability to endure pain changed as a function of the
manipulation of coping (Jensen, Turner, & Romano, 2001; Smeets, Vlaeyen, Kester, &
Knottnerus, 2006; Turner, Dworkin, Mancl, Huggins, & Truelove, 2001; Turner, Mancl, &
36
Aaron, 2006). Nevertheless, the absence of such a manipulation check tempers a
causal inference regarding the effect of changing expectations as the mechanism for
change (increased/decreased endurance) in the pain experience.
Another design limitation is that experimenters were not blinded to the condition or
the hypotheses. However, because the data were collected using objective time
measurements and electronic/mechanical devices it is unlikely this would introduce
experimenter bias. Furthermore, it is possible that the cold pressor task was not an
optimal analog of chronic clinical pain and that other pain induction strategies would
have been more appropriate. Of note, there is no evidence of systematic variance due
to variation in the water temperature in the cold pressor and, thus, no concern of
confound effects. As noted in the materials and methods section, the temperature
variation is within standard parameters of the cold pressor task. It should also be noted
that no data are available regarding the reliability and validity of the pressure sensitive
bladder/transducer used to measure pain intensity. This precludes comparison of our
obtained measurements with those obtained from existing well-established methodology
for measuring pain intensity such as Visual Analog Scale (VAS).
Our reliance on PSR as a measure of pain endurance strongly reduced our
sample size from 58 to 39, excluding 19 participants for whom PSR could not be
calculated. The reduction in sample size may have rendered our study underpowered
and may influence the validity of our results. Nonetheless, it should be noted that the
exclusion of participants was not selective as the two groups did not differ significantly
in between-group analyses of demographic variables. In evaluating our results, it is
important to consider the brevity and limited scope of our coping manipulation strategy.
37
Thus, it is suggested that further experimental research be conducted on the effects of
catastrophizing and positive coping in the pain experience using more diverse chronic
pain samples as well as different pain manipulation strategies. Additional measures of
expectation, both situational and dispositional, are important to further understand the
potential of expectancies as a mechanism in pain coping strategies, both positive and
negative. Lastly, it would be of interest to assess pre-existing coping predispositions
prior to pretest and test phase in order to allow for potential associations between
habitual (baseline) coping response predispositions and the effects of experimental
manipulation of coping. Assessing pre-existing coping predispositions would also allow
experimenters to discern if there are differential results when participants are assigned
to a coping condition contradicting their habitual coping style as compared to being
assigned to a coping condition that is consistent with their preferred coping strategy
repertoire.
38
CHAPTER 5 SUMMARY
This study investigated the effects of chronic pain patients’ response expectancies
on pain endurance and peak pain intensity measurements during an experimental pain
task. Response expectancies were manipulated by manipulating participants’ coping
behaviors to induce catastrophizing or positive coping following pain experimentally
induced using a cold-pressor. Fifty-eight participants were asked to complete the cold
pressor task (immersion of non-dominant hand in a bath of cold water) as part of the
pretest. Ensuing pain endurance and perceived peak pain intensity measurements were
established. Participants selected a coping statement (either a catastrophizing self-
statement or a positive coping self-statement depending on random group assignment)
from a list of seven self-statements. Using their selected coping statement, participants
repeated the cold pressor task during the test phase. Pain endurance and peak pain
intensity measurements were subsequently reestablished.
Whereas during the pretest participants’ pain endurance and peak pain intensity
ratings did not differ, participants assigned to the positive coping self-statement
condition endured pain for a significantly longer duration of time during the test phase
as compared to participants assigned to the catastrophizing self-statement condition.
Interestingly, peak pain intensity ratings were not affected by the manipulation of
participants’ coping response as there were no differences between the groups’
measurements from pretest to test phase. Collectively, these results indicate that the
manipulation of participants coping responses led to them to endure pain differentially
during the test phase despite experiencing the same intensity of pain as experienced
during the pretest. These results suggest that the manipulation of response
39
expectancies via the manipulation of coping strategies is responsible for changes in the
pain experience as indicated by the changes in pain endurance observed in this study.
40
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BIOGRAPHICAL SKETCH
Daniela Roditi was born in Mexico City, Mexico. She is the daughter of Alberto
Roditi and Gabriela Dominguez. Daniela has a younger sister, Ana Laura Roditi, and an
older brother, Guillermo Roditi. Daniela graduated summa cum laude from Stetson
University in May 2008 with a Bachelor of Arts in psychology and a minor in health care
issues. She is currently residing in Gainesville, Florida and is pursuing a doctorate in
clinical and health psychology at the University of Florida.
Daniela’s research interests include coping behaviors, response expectancies,
and the use of analgesic placebos. Daniela is currently furthering her clinical training
experience in various settings. Her clinical experience includes conducting pediatric
neuropsychological assessments, structured comprehensive assessments specific to
populations of people with anxiety disorders, a range of medical psychology
assessments, and conducting psychological assessments with children. Daniela is also
currently involved in a randomized controlled clinical trial comparing the effects of
different cognitive behavioral therapies in a sample of fibromyalgia patients. Current
volunteer experiences include providing free brief therapy at a local community center
for residents of the community in need of psychological services. Daniela’s aspirations
within the field of clinical health psychology include an academic career that involves a
balance of teaching and clinical research opportunities.