(284) Investigating the role of pain behaviors in the association between patients’ pain catastrophizing and their partners’ burden

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Abstracts

The Journal of Pain

Johnson-Neyman technique was used to determine the regional effect of the moderation, which indicated that when PCS scores are > 10.6, capsaicin pain significantly moderates the association between pain and area of secondary hyperalgesia. The important role for catastrophizing in contributing to secondary hyperalgesia, and potentially central sensitization, warrants further research.

(281) Pain catastrophizing predicts post-surgical changes in physical functioning in total knee replacement patients M Cornelius, R Edwards, A Lazaridou, and O Franceschelli; Brigham and Women’s Hospital, Boston, MA

Total knee replacement (TKR) surgery is a beneficial and cost-effective treatment for end-stage osteoarthritis; however, patients experience remarkable variability in post-operative pain and functional outcomes. Identifying the determinants of post-TKR functional outcomes is a critical step in identifying potentially high-risk patients and refining adjunctive therapies to improve outcomes in that subgroup. Our study collected data from n= 62 (31 females) participants with knee osteoarthritis who were scheduled to undergo unilateral TKR. Participants completed psychological questionnaires such as the Pain Catastrophizing Scale (PCS). Participants also completed several physical functioning measures, including the six-minute walk test and a stair climbing task which assessed how quickly subjects could ascend and descend a flight of stairs. Such indices of physical functioning are an important component of patient recovery, underlying an array of daily activities necessary for independent living. We found that functioning improved significantly (i.e., walk distances increased and stair climbing times decreased) from pre-surgery to 3 months post-surgery (p’s< .05), with substantial variability across patients. In addition, indices of knee pain intensity and pain catastrophizing decreased after surgery (p’s< .05). We used linear regression to examine the unique effects of catastrophizing on functional outcomes after surgery, controlling for changes in pain intensity after surgery. Results indicated that pre-surgically, higher levels of pain catastrophizing were associated with lower 6-minute walk distances and higher stair-climbing times. When examining pre- to post-surgery changes in function, changes in catastrophizing predicted changes in walking distance (p<0.01), when controlling for pain, and catastrophizing was also a predictor of improved ability to climbed stairs (p<0.01), controlling for changes in pain. Collectively, it appears that catastrophizing impacts physical functioning and clinical outcomes after total joint replacement surgery; patients who experience the largest reductions in catastrophizing show the greatest post-TKR improvements in function. Clinical applications and treatment implications will be discussed.

(282) Does State Pain catastrophizing Mediate the Relationship between Trauma Exposure and Spinal Nociceptive Processing? €ereca, N Hellman, C Sturycz, B Kuhn, E Lannon, S Palit, Y Gu M Payne, J Shadlow, and J Rhudy; The University of Tulsa, Tulsa, OK Chronic pain is prevalent in those with trauma exposure; however, the mechanisms of this relationship are unknown. Research suggests catastrophizing is independently associated with pain and trauma severity, but to our knowledge no study has examined the relationships between catastrophizing, trauma exposure, and nociceptive processing in one model. Central sensitization (hyperexcitability of spinal neurons) is a possible mechanism which could explain the observed link between trauma exposure and subsequent chronic pain. The nociceptive flexion reflex (NFR) is a measure of spinal nociception and chronic pain is associated with lower NFR thresholds (lower stimulus intensities elicit the reflex) suggesting NFR can be used to assess central sensitization. The present study investigated if state catastrophizing mediates the relationship between traumatic life events and NFR threshold in 158 currently healthy, pain-free individuals (76 women). Participants completed the Life Events Checklist (a measure of trauma exposure frequency), a state version of the Pain Catastrophizing Scale (PCS; a measure of catastrophizing during pain testing), and a laboratory paradigm to assess NFR threshold. Mediation analyses using 2000 bootstrapped samples indicated a significant indirect path between traumatic events and NFR via pain catastrophizing (a*b path=0.22, 95%CI=0.02, 0.56). Additional bootstrapped mediation analyses investigated if any subscale of the PCS (rumination, magnification, helplessness) was responsible for the indirect effect; however, the results of these analyses were non-significant.

These findings lend support for the relationship between trauma exposure and pain, however the positive indirect effect suggests central sensitization may not be the mechanism and instead posits stressinduced hypoalgesia. Specifically, survivors of traumatic events may catastrophize when experiencing painful stimuli to produce stressinduced hypoalgesia, possibly fatiguing inhibitory mechanisms over the long-term and promoting chronic pain risk. However, this is speculative until further research can test this hypothesis.

(283) Temporal associations among state pain catastrophizing, pain intensity, and pain tolerance in the cold pressor task: The effect of prior experience with cold thermal stimuli R Gibler, E O’Bryan, T Ross, and K Jastrowski Mano; University of Cincinnati, Cincinnati, OH

Pain catastrophizing is associated with heightened pain sensitivity. Though the predictability of painful experiences is associated with increased pain tolerance, studies have not specifically examined the effect of prior experience with cold thermal stimulation on pain responses in the cold pressor task (CPT). Moreover, the temporal association between prior experience with cold stimuli and pain catastrophizing in the CPT is unclear. We examined the effect of prior experience with cold stimuli (i.e., icing an injury) on pain catastrophizing immediately before and during the CPT in a healthy sample of N = 165 (59.4% female) undergraduate participants. Participants reporting a history of icing an injury (n = 108) reported lower state pain catastrophizing both before (d =.15) and during the CPT (d = .26), as well as lower pain intensity (d = .31) and higher pain tolerance (d = .28) relative to participants without a history of icing (n = 53). Difference scores indicated that participants, regardless of icing experience, reported higher pain catastrophizing during the CPT compared to before the task. However, the change in catastrophizing was smaller for those reporting previous icing experience. State pain catastrophizing both before and during the CPT was predictive of lower pain tolerance (b = -.19, p = .02 and b = -.44, p < .001, respectively). Results are consistent with research suggesting that the predictability of painful experiences corresponds to lower pain sensitivity. It is possible that prior experience with cold thermal stimulation lessens the threat value of experimental cold pain paradigms. Future research is needed to clarify which types of previous experiences with cold stimuli are most predictive of decreased pain catastrophizing and pain sensitivity in experimental tasks, as well as to determine the role played by the degree of pain and unpleasantness associated with those experiences.

(284) Investigating the role of pain behaviors in the association between patients’ pain catastrophizing and their partners’ burden S Mohammadi, N Rosen, and C Chambers; IWK Health Centre, Halifax, NS, Canada

Pain catastrophizing in individuals with chronic pain (ICPs) is related to lower levels of well-being (e.g., burden and stress) in their family members, especially their partners. Yet, the role of behavioral factors in the association between pain catastrophizing and partners’ well-being has remained largely unexplored. The ICPs who catastrophize about their pain are likely to express more pain-related behaviors, such as guarding. Pain behaviors convey patients’ pain experience to their partners and increase the chances of receiving support from them. While ICPs benefit from partner support, providing continuous support may cause higher levels of burden in the partners of ICPs. This study hypothesized that ICPs with higher levels of pain catastrophizing would express more pain behaviors. In turn, more pain behaviors would be positively related to partner burden. Using a multiple mediation analysis, the current study investigated the mediating role of different types of pain behaviors including distorted ambulation (e.g., stooping), affective distress (e.g., being angry), facial/audible expressions (e.g., grimacing), and seeking help (e.g., asking for help) on the link between pain catastrophizing and perception of partner burden. The sample consisted of 119 ICPs. ICPs completed questionnaires on pain catastrophizing (i.e., Pain Catastrophizing Scale-13), pain behaviors (i.e., Pain Behavior Checklist), and perceptions of their partner’s burden (i.e., Zarit Burden Inventory) in an online survey. The findings showed that pain catastrophizing was significantly related to higher perception of partner burden (p = <.001). Furthermore, the

Abstracts

results of the multiple mediation analysis showed that the link between pain catastrophizing and perception of partner burden was only mediated by an increase in behaviors related to affective distress (95% CI: 01-.4). These findings indicate that ICPs’ pain behaviors related to affective distress such as being angry or upset, may be accountable for the positive association between greater catastrophizing and greater perception of partner burden.

(285) Gender, but not resilience or catastrophizing, is associated with habituation of heat pain thresholds P Slepian and C France; Ohio University, Athens, OH Habituation to repeated noxious stimulation is an important marker of successful adaptation to pain, and has been demonstrated to be influenced by numerous factors, including gender, psychosocial factors, and the physical properties of the stimulus. Indeed, a sole prior study identified a relationship between resilience and habituation of heat pain thresholds. We attempted to replicate these findings by having 105 undergraduate participants (61 female) undergo a series of five heat pain thresholds, delivered at 30 second intervals. Multi-level growth curve analyses were conducted to examine shape and determinants of habituation. Fit indices and model parsimony considerations dictated that the logarithmic growth curve was a better fit than either linear or quadratic curves. Addition of person-level variables, including gender, pain catastrophizing, and pain resilience and their interactions with the growth curve, significantly improved model fit, DX2LR(6, N= 105) = 22.70, p < 0.001. In the final model, random intercepts and slopes were negatively correlated, Z = -3.73, p < 0.001. There was a significant interaction between gender and the growth curve, b = 0.47, p = 0.03, indicating that women demonstrated greater habituation of heat pain thresholds, as well as a simple effect of gender, b = -2.47, p = 0.001, such that women evidenced significantly lower initial heat pain thresholds. Neither pain resilience nor pain catastrophizing moderated the slope of the growth curve, both p’s > 0.05. All possible interactions among sex, psychosocial factors, and the growth curve were examined, and none were significant. These findings confirm prior evidence that women experience both enhanced habituation of pain and increased initial pain sensitivity. However, we were unable to replicate findings from the prior study linking resilience to habituation of heat pain thresholds. Non-replication will be discussed in light of participant characteristics and theoretical considerations of resilience.

CPM (286) Optimizing conditioned analgesia in healthy volunteers for translational applications B Alter, I Strigo, and H Fields; University of California, San Francisco, San Francisco, CA

Pain and the relief of pain are strongly affected by learning. Classical conditioning techniques have been used in experimental settings to produce analgesia. In healthy volunteers, neutral visual or auditory cues (conditioned stimuli, CS) can be paired with an analgesic manipulation (unconditioned stimulus, UCS) to elicit conditioned analgesia. Despite these discoveries, the key characteristics of the CS and UCS required for optimal analgesia are largely unknown, including the timing between CS and UCS and whether multimodal audiovisual cues are more efficacious than auditory or visual cues. The current study addresses these questions. All procedures were approved by the UCSF IRB. Healthy, 18-50 year old, male and female volunteers were recruited. Standardized psychological instruments assessing depression (BDI), anxiety (STAI), and pain catastrophizing (PCS) were administered. Thermodes were applied to the volar forearm and subjects were asked to rate their pain on a computerized visual analogue scale with a slider allowing for real-time VAS report. Analgesic manipulations serving as the UCS included offset analgesia and cooling of capsaicin-sensitized skin. Conditioning stimuli include color fields with text (‘‘pain relief’’), beep tones, or both. Subjects were presented CS-UCS pairings followed by test runs in which the CS was presented without the analgesic manipulation. Between and within subject comparisons were made across different CS groups and controls. Preliminary data demonstrate the feasibility of the current study design. Neutral cues contingently paired with offset analgesia can elicit analgesia when subsequently presented to the subject. Future research will elucidate key characteristics of the conditioning cues, with the goal of clinical application.

The Journal of Pain

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Supported by a grant from Foundation for Anesthesia Education and Research.

(287) Supraspinal modulation of pain and the nociceptive flexion reflex (NFR): is emotional modulation correlated with conditioned pain modulation? E Lannon, B Kuhn, S Pali, M Payne, C Sturycz, Y Guereca, K Thomoson, J Fisher, S Herbig, N Hellman, J Shadlow, and J Rhudy; University of Tulsa, Tulsa, OK

Conditioned pain modulation (CPM) and emotional controls of nociception (ECON) are, in part, due to activation of supraspinal structures that modulate pain signaling at the spinal level. The present study assessed CPM and ECON modulation of pain and a reflex used as a marker of spinal nociception (nociceptive flexion reflex, NFR). 172 healthy pain-free individuals completed ECON, CPM, and a control task for CPM (CPM-Sham). During ECON, pain and NFR were recorded in response to electrocutaneous stimulations while viewing positive (e.g., people in sexual acts), negative (e.g., human injuries), and neutral (e.g., household objects) pictures. During CPM, pain and NFR were recorded in response to electrocutaneous stimulations, before, during and after a conditioning stimulus (cold pressor test, 10C water). For CPM-Sham, procedures were the same except the conditioning stimulus was non-painful (26C water). Order of CPM and CPMSham were counterbalanced. Change scores were computed for ECON (pain/NFR during negative pictures minus pain/NFR during positive pictures) and CPM/CPM-Sham (pain/NFR during conditioning phases minus pain/NFR during baseline phases). Participants rated the expected change in pain from the conditioning phases and the baseline phases in CPM and CPM-Sham. Outlier’s were detected and excluded with modified one-step M-estimators. A negative correlation was found between modulation of pain during ECON and CPM (r=-.18, p=.01), but not CPM-Sham (r=-.02, p=.40). Similarly, a negative correlation was found between modulation of NFR during ECON and CPM (r=-.15, p=.03), but not CPM-Sham (r=-.04, p=.33). Results suggest that greater modulation of pain and spinal nociception in ECON is related to greater inhibition of pain and spinal nociception in CPM however, the magnitude of the relationships are small suggesting relatively distinct processes.

(288) The temporal stability of conditioned pain modulation and temporal summation of pain in healthy older adults T Ohlman, L Miller, and K Naugle; Indiana University- Purdue University, Indianapolis, Indianapolis, IN

The temporal stability (i.e., test-retest reliability) of temporal summation of pain (TS) and conditioned pain modulation (CPM) has been established in young and middle-aged healthy adults; however, little data is available on the temporal stability of these tests in populations characterized by abnormal pain modulation, including older adults. Thus, the purpose of this study was to evaluate the temporal stability of TS and CPM in healthy older adults. The study also examined factors that might impact the stability of TS and CPM. In a test-retest study, 40 healthy older adults (19 men, 60-79 years old) completed a training session and two sessions of quantitative sensory testing (QST) within a 2-week period that included the following QST tests: 1) TS of heat pain at 46oC, 48oC, and 50oC on forearm, 2) TS of mechanical pain on forearm and hand, 3) CPM which included pressure pain thresholds (CPM-PPT) and prolonged suprathreshold heat pain (CPM-Heat) as test stimuli and a cold water bath as conditioning stimulus. Participants also completed the Pain Catastrophizing Scale (PCS) and Graded Chronic Pain Scale (GCPS). TS and CPM scores were calculated for each test. The absolute stability (time x sex ANOVA), relative stability (Interclass correlation coefficients: ICCs), and intra-individual stability coefficients were examined for each variable. Overall, results for TS showed good to excellent stability (ICC’s=0.63-0.92), except for heat TS at 50oC for women (ICC-0.51). Correlational analyses indicated that greater intra-individual stability for mechanical TS was associated with less pain catastrophizing and lower intensity of self-reported pain on the GCPS. The results showed moderate stability for CPM-Heat (ICC=0.57), but poor stability for CPM-PPT (ICC=0.18). Our findings suggest sufficient reliability for TS in older adults, whereas the reliability of CPM may depend on the test-stimulus. This study was