Personality factors in the explanation of sex differences in pain catastrophizing and response to experimental pain

Predictors for severe persisting pain in rheumatoid arthritis are associated with pain origin and appraisal of pain

OBJECTIVES

To determine the proportion of patients with rheumatoid arthritis (RA) with severe persisting pain and to identify predictive factors despite treatment-controlled disease activity.

METHODS

This prospective multicentre study included outpatients with RA scheduled for escalation of anti-inflammatory treatment due to active disease and severe pain (Disease Activity Score 28 (DAS28)>3.2 and Visual Analogue Scale (VAS)>50). At week 24, patients were stratified into reference group (DAS28 improvement>1.2 or DAS28≤3.2 and VAS pain score<50), non-responders (DAS28 improvement≤1.2 and DAS28>3.2, regardless of VAS pain score) and persisting pain group (DAS28 improvement>1.2 or DAS28≤3.2 and VAS pain score≥50). The former two subgroups ended the study at week 24. The latter continued until week 48. Demographic data, DAS28-C reactive protein, VAS for pain, painDETECT Questionnaire (PD-Q) to identify neuropathic pain (NeP) and the Pain Catastrophising Scale were assessed and tested for relation to persisting pain.

RESULTS

Of 567 patients, 337 (59.4%) were classified as reference group, 102 (18.0%) as non-responders and 128 (22.6%) as patients with persisting pain. 21 (8.8%) responders, 28 (35.0%) non-responders and 27 (26.5%) persisting pain patients tested positive for NeP at week 24. Pain catastrophising (p=0.002) and number of tender joints (p=0.004) were positively associated with persisting pain at week 24. Baseline PD-Q was not related to subsequent persisting pain.

CONCLUSIONS

Persisting and non-nociceptive pain occur frequently in RA. Besides the potential involvement of NeP, pain catastrophising and a higher number of tender joints coincide with persisting pain.

Association Between Pain Coping and Symptoms of Anxiety and Depression, and Work Absenteeism in People With Upper Limb Musculoskeletal Disorders: A Systematic Review and Meta-analysis

OBJECTIVE

To determine the prospective association of pain coping strategies and symptoms of anxiety and depression with work absenteeism in people with upper limb musculoskeletal disorders.

DATA SOURCES

A systematic search of PubMed, Web of Science, Embase, Cochrane Library, and Scopus databases was conducted from inception to September 23, 2022.

STUDY SELECTION

Prospective observational studies of adults with upper limb musculoskeletal disorders were included. Included studies had to provide data on the association of pain coping strategies (catastrophizing, kinesiophobia, self-efficacy or fear avoidance) or symptoms of anxiety and depression with work absenteeism.

DATA EXTRACTION

Study selection, data extraction, and assessment of methodological quality (Newcastle Ottawa Scale) were performed by 2 independent authors. Random-effects models were used for quantitative synthesis.

DATA SYNTHESIS

Eighteen studies (n=12,393 participants) were included. Most studies (77.8%) reported at least 1 significant association between 1 or more exposure factors (pain coping strategies or symptoms of anxiety and depression) and work absenteeism. Meta-analyses showed a statistically significant correlation between the exposure factors of catastrophizing (r=0.28, 95% confidence interval [CI]: 0.15 to 0.40; P<.0001) and symptoms of anxiety and depression (r=0.23, 95% CI: 0.10 to 0.34; P=.0003) with work absenteeism. The correlation between self-efficacy and work absenteeism was non-significant (r=0.24, 95% CI: -0.02 to 0.47; P=.0747).

CONCLUSIONS

Rehabilitation teams should consider assessing catastrophizing and symptoms of anxiety and depression to identify patients at risk for work absenteeism. Addressing these variables may also be considered in return-to-work programs for individuals with upper limb disorders.

An investigation into how accurately UK rabbit owners identify pain in their pet rabbits

BACKGROUND

Rabbits are popular family pets. They are prey species and so have evolved to hide signs of illness and pain. Recent research has developed robust pain scales for use in a clinical setting, but to date none has examined rabbit owners' ability to recognise pain in their animals. This study investigated how owners identify pain in their pet rabbits and their ability to correctly identify different levels of pain, in order to determine any need for owner education in this area.

METHODS

Owners were recruited via Facebook and a two-part online survey was distributed. Part one collected data on demographics, owners' knowledge of pain signs and beliefs about pain in rabbits. Part two asked respondents to pain score eight videos of rabbits in different levels of pain for comparison to pain scores made by three experts. We used a simplified version of the Bristol Rabbit Pain Score (BRPS) which involved a single 0 to 3 scale. We explored the number of pain signs each respondent could list, the total score given to the videos, and their deviation from the experts' scores.

RESULTS

A total of 500 respondents completed part one of the survey and 345 additionally completed Part two. Respondents were on average able to state five signs of pain (range 0-12), but females stated significantly more (p = 0.018), as did those who worked with rabbits (p = 0.004) and those with experience of their rabbit having an operation (p = 0.01). Overall, 98.6% of respondents thought rabbits felt pain as much or more that dogs and cats. In Part two, respondents more frequently agreed with the experts when identifying rabbits in no pain (88.8%) and severe pain (65.2%), but there was lower agreement when identifying mild (28.4%) and moderate pain (43.2%). Respondents overall rated pain lower than experts with an average total pain score of 11.9 compared to 18 given by the experts.

CONCLUSIONS

Most rabbit owners are able to list numerous pain signs and are generally able to identify pain-free rabbits and those in severe pain. Owners' ability to differentiate between mild and moderate pain is more limited and could benefit from training in the subtler signs of pain. Veterinary professionals are well placed to educate owners about signs of pain in rabbits and should be aware of areas where owners' knowledge can be improved.

The effect of induced optimism on early pain processing: indication by contact heat evoked potentials (CHEPs) and the sympathetic skin response (SSR)

Situationally induced optimism has been shown to influence several components of experimental pain. The aim of the present study was to enlarge these findings for the first time to the earliest components of the pain response by measuring contact heat evoked potentials (CHEPs) and the sympathetic skin response (SSR). Forty-seven healthy participants underwent two blocks of phasic thermal stimulation. CHEPs, the SSR and self-report pain ratings were recorded. Between the blocks of stimulation, the 'Best Possible Self' imagery and writing task was performed to induce situational optimism. The optimism manipulation was successful in increasing state optimism. It did, however, neither affect pain-evoked potentials nor the SSR nor self-report pain ratings. These results suggest that optimism does not alter early responses to pain. The higher-level cognitive processes involved in optimistic thinking might only act on later stages of pain processing. Therefore, more research is needed targeting different time frames of stimulus processing and response measures for early and late pain processing in parallel.

Exploring the contributions of sex and traditionally genderized interpersonal-expressive traits to variability in post-trauma pain ratings

OBJECTIVES

Multiple intra- and inter-individual variabilities sculpt the experience of pain. However, integration of sex and gender has been under-explored in explanatory models of pain. This study aimed to examine the role of sex and traditionally genderized interpersonal-expressive traits, and their interactions in explaining the variability of pain ratings.

METHODS

Data from 113 participants following acute non-catastrophic musculoskeletal (MSK) injuries were included. Participants completed the Brief Pain Inventory (BPI) and the Gender, Pain and Expectations Scale (GPES). An independent T-test was used to compare differences in BPI subscales between the sexes. Pearson correlations explored the associations between BPI and GPES subscale scores for the overall sample and also for the sample when disaggregated by sex. Multiple linear regression was used to investigate the interaction of sex and gender traits in explaining the BPI scores.

RESULTS

No differences were found between the sexes in mean BPI Severity and Interference. Across sexes, Relationship-oriented was positively associated with greater BPI Severity (r = 0.20) and Emotive was positively associated with BPI Interference (r = 0.24). In sex-disaggregated analyses, these associations were significant in females only. Goal-oriented was associated with neither BPI Severity nor Interference. In multivariate regression, only Emotive was a significant predictor of BPI Interference.

DISCUSSION

The findings suggest that variances in pain-related interference are partially explained by scores on a scale measuring self-perceptions of Emotive qualities. Sex was not predictive of either pain outcome in both bivariate and multivariate analyses. Researchers and clinicians are encouraged to consider both sex- and gender-based variables when interpreting patient pain reports.

Determination of pain intensity, pain-related disability, anxiety, depression, and perceived stress in Polish adults with temporomandibular disorders: A prospective cohort study

BACKGROUND

There is a need to assess a relationship between the psychoemotional state of patients and the occurrence and the intensity of pain and temporomandibular disorders (TMD) in relation to a Polish population. There are no such precision data in the literature relating to the population of big Eastern European country. The study conducted by the authors refer to a large group of male and female adult patients of the Polish population in a different age profile. As a result, this study provides a picture of the situation that also takes into account population characteristics that may affect the clinical situation of patients.

OBJECTIVE

The aim of the study was to assess the pain intensity, pain-related disability, anxiety, depression, and perceived stress among Polish adults with TMD as well as the association between psychosocial impairment and TMD.

MATERIALS AND METHODS

This prospective cohort study included 219 adult patients from the Outpatient Clinic for Temporomandibular Disorders at the Academic Dental Polyclinic in Wroclaw. The patients completed validated questionnaires, and received a TMD diagnosis based on a standardized examination (Diagnostic Criteria for Temporomandibular Disorders) performed by a qualified dentist. A statistical analysis was carried out on the collected data.

RESULTS

Myalgia was the most commonly diagnosed condition among the TMD patients. Furthermore, the prevalence of perceived stress, anxiety, and depression was high in the studied sample. Females showed more depression symptoms than males, while the level of anxiety and stress was similar in both groups. The most statistically significant correlation was observed between the group of masticatory muscle disorders and the level of depression, stress, pain intensity, and pain-related disability.

CONCLUSION

Due to the high prevalence of increased levels of anxiety, depression, and perceived stress, it is essential to screen the psychosocial status of Polish TMD adult patients. Psychosocial status may have an impact on a studied patient's response to treatment and pain intensity, and pain-related disability. Therefore, Polish TMD adult patients should be provided with management based on an interdisciplinary approach.

CLINICAL TRIAL REGISTRATION

[https://clinicaltrials.gov/], identifier [NCT05183503].

Test-Retest Reliability of an Adaptive Thermal Pain Calibration Procedure in Healthy Volunteers

Quantitative sensory testing (QST) allows researchers to evaluate associations between noxious stimuli and acute pain in clinical populations and healthy participants. Despite its widespread use, our understanding of QST’s reliability is limited, as reliability studies have used small samples and restricted time windows. We examined the reliability of pain ratings in response to noxious thermal stimulation in 171 healthy volunteers (n = 99 female, n = 72 male) who completed QST on multiple visits ranging from 1 day to 952 days between visits. On each visit, participants underwent an adaptive pain calibration in which they experienced 24 heat trials and rated pain intensity after stimulus offset on a 0 to 10 Visual Analog Scale. We used linear regression to determine pain threshold, pain tolerance, and the correlation between temperature and pain for each session and examined the reliability of these measures. Threshold and tolerance were moderately reliable (Intra-class correlation = .66 and .67, respectively; P < .001), whereas temperature-pain correlations had low reliability (Intra-class correlation = .23). In addition, pain tolerance was significantly more reliable in female participants than male participants, and we observed similar trends for other pain sensitive measures. Our findings indicate that threshold and tolerance are largely consistent across visits, whereas sensitivity to changes in temperature vary over time and may be influenced by contextual factors.

Exploration of the trait-activation model of pain catastrophizing in Native Americans: results from the Oklahoma Study of Native American pain risk (OK-SNAP)

OBJECTIVES

Native Americans (NAs) have the highest prevalence of chronic pain of any racial/ethnic group. This issue has received little attention from the scientific community. One factor that may contribute to racial pain disparities is pain catastrophizing. Pain catastrophizing is a construct related to negative pain outcomes in persons with/without chronic pain. It has been suggested that the relationship between trait catastrophizing and pain is mediated by situation-specific (state) catastrophizing. The present study has 2 aims: (1) to investigate whether state pain catastrophizing mediates the relationship between trait catastrophizing and experimental pain (e.g., cold, ischemic, heat and electric tolerance), and (2) to investigate whether this relationship is stronger for NAs.

METHODS

145 non-Hispanic Whites (NHWs) and 137 NAs completed the study. Bootstrapped indirect effects were calculated for 4 unmoderated and 8 moderated mediation models (4 models with path a moderated and 4 with path b).

RESULTS

Consistent with trait-activation theory, significant indirect effects indicated a tendency for trait catastrophizing to be associated with greater state catastrophizing which in turn is associated with reduced pain tolerance during tonic cold (a × b=-0.158) and ischemia stimuli (a × b=-0.126), but not during phasic electric and heat stimuli. Moderation was only noted for the prediction of cold tolerance (path a). Contrary to expectations, the indirect path was stronger for NHWs (a × b for NHW=-.142).

CONCLUSIONS

Together, these findings suggest that state catastrophizing mediates the relationship between trait catastrophizing and some measures of pain tolerance but this indirect effect was non-significant for NAs.

The Influence of Examiner Gender on Responses to Tonic Heat Pain Assessments: A Preliminary Investigation

Background: The influence of examiner gender on pain reporting has been previously explored in both research and clinical settings. However, previous investigations have been limited, with the majority of studies employing single, static assessments of pain (e.g., cold pressor test, verbal pain ratings). The impact of examiner gender on both static and dynamic heat-based pain assessments is currently unknown.

Methods: Thirty eight participants (20 females aged 24.1 ± 4.44, and 18 males, aged 24.8 ± 4.54) completed two identical testing sessions, randomized to a male and female examiner in a cross-over design. Pain sensitivity was examined using heat pain thresholds, verbal pain ratings to tonic heat, computerized visual analog scale (CoVAS) rating to tonic heat, and participant-controlled temperature (PCT) heat pain assessments.

Results: Female participants reported higher verbal pain to tonic heat with a female examiner compared to male participants, with similar trends for CoVAS responses to tonic heat. Conversely heat pain thresholds and PCT were not significantly influenced by experimenter gender.

Conclusions: Overall, verbal ratings were the most impacted by examiner gender, with temperature-based methods such as PCT and pain thresholds showing little to no examiner gender effects. While the gender of the examiner may be an important consideration in the measurement of sex and gender differences in pain research, the choice of pain assessment method may be of similar consequence.

The Association Between Adverse Life Events, Psychological Stress, and Pain-Promoting Affect and Cognitions in Native Americans: Results from the Oklahoma Study of Native American Pain Risk

Native Americans (NAs) experience higher rates of chronic pain. To examine the mechanisms for this pain inequity, we have previously shown that NAs report higher levels of pain-related anxiety and pain catastrophizing, which are in turn related to pronociceptive (pain-promoting) processes. But, it is currently unclear why NAs would report greater pain-related anxiety and catastrophizing. Given that NAs are also more likely to experience adverse life events (ALEs) and associated psychological distress, it was hypothesized that higher anxiety/catastrophizing in NAs would be partially explained by higher rates of ALEs and psychological distress. Structural equation modeling was used to analyze these pathways (NA ethnicity ➔ ALEs ➔ psychological distress ➔ pain anxiety/catastrophizing) in 305 healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Pain-related anxiety and situational pain catastrophizing were assessed in response to a variety of painful tasks. The Life Events Checklist was used to assess cumulative exposure to ALEs that directly happened to each participant. A latent psychological distress variable was modeled from self-reported perceived stress and psychological symptoms. Results found that NAs experienced more ALEs and greater psychological distress which was associated with higher rates of pain-related anxiety and pain catastrophizing. Notably, NAs did not report greater psychological distress when controlling for ALE exposure. This suggests that a higher risk of chronic pain in NAs may be due, in part, to psychological distress, pain-related anxiety, and pain catastrophizing that are promoted by exposure to ALEs. These results highlight several targets for intervention to decrease NA pain risk.

The Spatial Extent of Pain Is Associated with Pain Intensity, Catastrophizing and Some Measures of Central Sensitization in People with Frozen Shoulder

The aim of this cross-sectional study was to explore the spatial extent of pain and its association with clinical symptoms, psychological features, and pain sensitization in people with frozen shoulder (FS). Forty-eight individuals with FS completed pain drawings (PDs) and reported their clinical symptoms including pain intensity (Visual Analogue Scale) and shoulder disability (Shoulder Pain and Disability Index). Moreover, pain sensitization measurements (pressure pain thresholds, temporal summation, conditioned pain modulation, and Central Sensitization Inventory (CSI)) were assessed. Psychological features were assessed by Pain Catastrophizing Scale (PCS) and Pain Vigilance and Awareness Questionnaire. Pain frequency maps were generated, Margolis rating scale was used for pain location, and Spearman correlation coefficients were computed. The mean (SD) pain extent was 12.5% (6.7%) and the most common painful area was the anterolateral shoulder region (100%). Women presented a more widespread pain distribution compared with men. Significant positive associations were obtained between pain extent and current pain intensity (rs = 0.421, p < 0.01), PCS (rs = 0.307, p < 0.05) and CSI (rs = 0.358, p < 0.05). The anterolateral region of the shoulder was the most common painful area in people with FS. Women with FS presented more extended areas of pain; and a more widespread distribution of pain was correlated with higher levels of pain, pain catastrophizing and pain sensitization.

Gender Biases in Estimation of Others' Pain

Caregiving and other interpersonal interactions often require accurate perception of others' pain from nonverbal cues, but perceivers may be subject to systematic biases based on gender, race, and other contextual factors. Such biases could contribute to systematic under-recognition and undertreatment of pain. In 2 experiments, we studied the impact of perceived patient sex on lay perceivers' pain estimates and treatment recommendations. In Experiment 1 (N = 50), perceivers viewed facial video clips of female and male patients in chronic shoulder pain and estimated patients' pain intensity. Multi-level linear modeling revealed that perceivers under-estimated female patients' pain compared with male patients, after controlling for patients' self-reported pain and pain facial expressiveness. Experiment 2 (N = 200) replicated these findings, and additionally found that 1) perceivers' pain-related gender stereotypes, specifically beliefs about typical women's vs. men's willingness to express pain, predicted pain estimation biases; and 2) perceivers judged female patients as relatively more likely to benefit from psychotherapy, whereas male patients were judged to benefit more from pain medicine. In both experiments, the gender bias effect size was on average 2.45 points on a 0-100 pain scale. Gender biases in pain estimation may be an obstacle to effective pain care, and experimental approaches to characterizing biases, such as the one we tested here, could inform the development of interventions to reduce such biases. Perspective: This study identifies a bias towards underestimation of pain in female patients, which is related to gender stereotypes. The findings suggest caregivers' or even clinicians' pain stereotypes are a potential target for intervention.

Recent advancements in tension-type headache: a narrative review

INTRODUCTION

Tension-type headache (TTH) is the most common primary headache disorder with a prevalence of up to 78% in general population and huge expenses in terms of health service. Despite its high incidence and impact on life's quality the knowledge on the pathophysiology and efficacious treatment of TTH was still limited.

AREAS COVERED

In recent years, a series of studies highlighted the heterogeneous nature of this pathology that seems to be determined by a complex interaction between genetic, environmental, and neuromuscular factors, which result in nociceptive system activation. In this setting, alongside the simple analgesic therapies used during the acute attack, a series of therapeutic options based on newly acquired experiences have taken hold.

EXPERT REVIEW

Not having a single substrate or a typical site of pathophysiology, TTH must be analyzed in a global and multidisciplinary way. Herein, we perform a narrative review of the most recent advancement stimulating the concept of this disease as the tip of the iceberg of a more complex individual malaise secondary to different alterations. Strategies based solely on symptomatic drugs should therefore be avoided by experienced personnel and treatment should aim at taking charge of the patient considering the processes behind this complex pathology.

Pain catastrophising in the oro-facial pain population

BACKGROUND

Pain catastrophising is a maladaptive cognitive response characterised by an exaggerated negative interpretation of pain experiences. It has been associated with greater disability and poorer outcomes in chronic pain, to include several specific oro-facial pain conditions. The goal of this study was to examine pain catastrophising at a military oro-facial pain specialty clinic.

METHODS

This retrospective chart review (RCR) examined information collected at initial examination from 699 new patients seen between September 2016 and August 2019 at the Orofacial Pain Center at the Naval Postgraduate Dental School (Bethesda, MD). Pain catastrophising, pain characteristics, psychosocial factors and sleep were assessed using standardised scales. Linear regression was used to evaluate associations of patient characteristics and pain intensity with pain catastrophising. Mediation analyses were done to characterise the extent to which the relationship between pain intensity and pain catastrophising may be explained by anxiety, depression and insomnia.

RESULTS

Higher pain intensity, depression, anxiety, insomnia and younger age were each associated with higher pain catastrophising (all p < .05). A primary diagnosis of neuropathic pain was the strongest independent predictor of higher pain catastrophising. The relationship between pain intensity and pain catastrophising was partially mediated by anxiety, depression and insomnia.

CONCLUSIONS

In this RCR of a population of oro-facial pain patients, those diagnosed with neuropathic pain were most likely to display high levels of pain catastrophising, a characteristic which is associated with poor long-term pain outcomes. This is the first study to show that, independent of other patient characteristics, those suffering from neuropathic pains displayed the highest levels of pain catastrophising. This highlights the importance of also addressing psychosocial factors in the treatment of neuropathic pain conditions, which are commonly treated using a predominantly biomedical approach. Additionally, anxiety, depression and insomnia each partially explains the relationship between pain intensity and pain catastrophising.

Comparative Evaluation of Different Numerical Pain Scales Used for Pain Estimation during Debonding of Orthodontic Brackets

Introduction

Patients experience various levels of discomfort during orthodontic treatment, i.e., after placement of separators, orthodontic implant placement, and archwire placement and during debonding. Various pain control methods have been developed to relive pain during debonding, i.e., finger pressure (FP), elastomeric wafer (EW), and stress relief (SR).

Aim

To analyse various pain scales commonly used to determine the effect of different pain control methods during debonding of orthodontic brackets. Study Design. A comparative cross-sectional study performed on a sample of 60 patients (n = 60) including 14 males and 46 females who were ready for debonding and who were divided into three groups, i.e., finger pressure (FP), elastomeric wafer (EW), and stress relief (SR).

Materials and Methods

A 100 mm Visual Analog Scale (VAS) was used to record the pain intensity for each tooth. Another scale known as Pain Catastrophizing Scale (PCS) was used to evaluate the patient's general attitude towards pain perception. The armamentarium and operator were kept same for all the patients. Statistical analysis used was the Kruskal-Wallis test, used for intergroup and intragroup comparison of pain scores.

Results

Lowest total pain score was recorded in the FP group (P=0.043) on intergroup comparison, while on intragroup comparison, higher pain scores were recorded in lower anterior region (P=0.02) in all three groups. There was no significant difference between the pain scores reported by the male and female subjects.

Conclusion

FP is an effective method of pain control. And teeth in the anterior region of lower and upper arches are more sensitive to pain. In terms of cognitive-affective constructs, although the VAS has been widely used in previous studies, the PCS has been detailed to show the most reliable association with physical discomfort and emotional distress.

Personality Traits in Burning Mouth Syndrome Patients With and Without a History of Depression

Objectives: So far, the strong link between neuroticism, chronic pain, and depression has been well-documented in literatures. Some suggested that they might share etiological factors, thus resulting in overlapping constructs. However, such effect has never been tested in burning mouth syndrome (BMS) patients, a complex phenomenon influenced by both neuropathic and psychopathological factors. We aim to clarify how personality affects individual's pain and pain-related experiences. Methods: Two hundred forty-eight patients with BMS provided demographic information and psychiatric history; completed Ten-Item Personality Inventory, a Visual Analog Scale of pain, and McGill Pain Questionnaire; and provided adequate parameters of depressive state, catastrophizing thinking, and central sensitization. Results: BMS patients with depression history suffered more severe clinical symptoms and scored higher in neuroticism and less in openness and extraversion than did those without psychiatric diagnoses. After age, sex, and duration of pain were controlled, neuroticism in BMS patients with depression correlates with affective dimension of pain. Instead, if psychiatric history is absent, neuroticism correlates with sensory dimension and pain intensity. In both groups, higher neuroticism, unlike other personality facets, contributed to a more severe clinical condition. Conclusion: Of the five traits, neuroticism appears to be the most crucial dimension associated with the pain symptoms and patient's conditions. This study implies that management of pain must extend beyond solely providing pain-relieving medication and must require a holistic and multidisciplinary approach.

Association of self-reported bruxism with temporomandibular disorders - Northern Finland Birth Cohort (NFBC) 1966 study

Objective: To investigate the prevalence of self-reported bruxism and its association with temporomandibular disorders (TMD). The hypothesis of the study was that self-reported bruxism is associated with TMD.Methods: The data were gathered from 1962 subjects who participated in a field study in 2012-2013, including a questionnaire concerning bruxism and TMD symptoms as well as clinical sub-diagnoses of TMD using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Statistical method was chi-square test. Bonferroni correction was made, and a p-value of <0.003 was considered as significant.Results: The prevalence of self-reported bruxism was 39.6%: 34.0% in men and 44.5% in women. Those who reported sleep bruxism (SB) or awake bruxism (AB) had significantly more pain-related TMD symptoms and signs compared to those not reporting bruxism.Conclusion: The prevalence of self-reported bruxism is high among middle-aged adults and is associated with TMD pain-related symptoms and signs, as well as TMD diagnoses.

Current perspectives on sex differences in tension-type headache

INTRODUCTION

Clinical and experimental evidence supports the presence of several gender differences in the pain experience.

AREAS COVERED

The current paper discusses biological, psychological, emotional, and social differences according to gender and their relevance to TTH. Gender differences have also been observed in men and women with tension-type headache and they should be considered by clinicians managing this condition. It appears that multimodal treatment approaches lead to better outcomes in people with tension-type headache; however, management of tension-type headache should consider these potential gender differences. Different studies have observed the presence of complex interactions between tension-type headache, emotional stress, sleep, and burden and that these interactions are different between men and women.

EXPERT OPINION

Based on current results, the authors hypothesize that treatment of men with tension-type headache should focus on the improvement of sleep quality and the level of depression whereas treatment of women with TTH should focus on nociceptive mechanisms and emotional/stressful factors. Future trials should investigate the proposed hypotheses.

Effects of (in)validation and plain versus technical language on the experience of experimentally induced pain: A computer controlled simulation paradigm

BACKGROUND AND OBJECTIVES

Amongst social contextual influences on pain, the manner in which pain and painful procedures are communicated to patients is considered an important contributor to the subjective experience of pain. Threatening information, e.g., by the use of technical language, is suggested to increase pain reports. Validation, or communicating understanding towards another person reporting personal experiences, is suggested to reduce pain. The current study examines effects of both information language (technical vs. plain language) and validation (validation vs. invalidation) on the subjective experience of experimentally induced pain.

METHODS

Pain-free participants (N = 132) were randomly assigned to one of four groups as formed by manipulations of validation and information language. After reading a description concerning the upcoming thermal stimulus formulated in technical or plain language, participants engaged in a computer controlled simulation (CCS; based on virtual reality technology). Participants received three thermal stimuli while interacting with an avatar who either validated or invalidated their experience during the CCS. Pain intensity and pain unpleasantness were assessed after each stimulus.

RESULTS

The validation manipulation showed to be effective, but the information language manipulation did not induce differential threat expectancies. Results show no effect of validation or information language on subjective pain reports.

LIMITATIONS

Suboptimality of the information language manipulation and shortcomings of the CCS procedure might account for current findings.

CONCLUSIONS

The study offers an interesting model for the further experimental study of isolated and combined effects of (social) contextual factors on pain. Diverse future research avenues are discussed.

Pain Catastrophising Predicts Alcohol Hangover Severity and Symptoms

Alcohol hangover is a cause of considerable social and economic burden. Identification of predictors of alcohol hangover severity have the potential to contribute to reductions in costs associated with both absenteeism/presenteeism and health care. Pain catastrophising (PC) is the tendency to ruminate and describe a pain experience in more exaggerated terms. The current study examines the possibility that this cognitive coping strategy may influence experience of alcohol hangover. The aims of the current study were to (1) examine the relationship between hangover severity and PC, (2) explore and identify discreet factors within the Acute Hangover Scale (AHS) and (3) explore whether independent factors/dimensions of acute hangover are differentially predicted by PC. A retrospective survey (n = 86) was conducted in which participants completed the Acute Hangover Scale (AHS); the Pain Catastrophising Scale (PCS); a questionnaire pertaining to the amount of alcohol consumed; and a demographic information questionnaire. Regression analyses showed a significant relationship between PC and hangover severity scores and demonstrated that PC was, in fact, a stronger predictor of perceived hangover severity than estimated peak blood alcohol concentrations (eBACs). Factor analysis of the AHS scale, resulted in the identification of two distinct symptom dimensions; ‘Headache and thirst’, and ‘Gastric and cardiovascular’ symptoms. Regression analyses showed that both eBAC and PCS score were significantly associated with ‘Headache and thirst’. However, only PCS score was associated with ‘Gastric and cardiovascular’ symptoms. These novel findings implicate a role for cognitive coping strategies in self-reports of alcohol hangover severity, and may have implications for understanding behavioural response to hangover, as well as suggesting that hangover and PC may be important factors mediating the motivation to drink and/or abuse alcohol, with potential implications in addiction research. Furthermore, these findings suggest that distinct alcohol hangover symptoms may be associated with different mechanisms underlying the experience of alcohol hangover.

Sex differences in negative affect and postoperative pain in patients undergoing total knee arthroplasty

Background

Knee osteoarthritis (OA) is among the most common and disabling persistent pain conditions, with increasing prevalence in the developed world, and affects women to a greater degree than men. In the USA, the growth of knee OA has been paralleled by an increase in rates of total knee arthroplasty (TKA), a surgical treatment option for late-stage knee OA. While TKA outcomes are generally good, postoperative trajectories of pain vary widely, with some patients reporting a complete absence of pain, but with a significant minority reporting worsening pain. Biopsychosocial factors, including anxiety and depression, are known to contribute importantly to the experience of joint pain, with women reporting a higher degree of negative affective symptoms.

Methods

This study investigated sex differences in TKA outcomes in age-matched groups of men and women at two academic medical centers. Pain and physical function were assessed in 100 patients (50 men and 50 women) during the perioperative period (preoperative visit—6 weeks postsurgical). The association of preoperative negative affect (anxiety and depression scores) to postoperative pain and function was evaluated, with specific attention to sex differences in this relationship.

Results

Overall, women reported more baseline pain-related physical dysfunction (although not higher baseline pain scores), as well as higher acute postoperative pain scores during the 2 weeks following TKA than their male counterparts. By 6 weeks postoperatively, sex differences in reported pain were no longer evident. Interestingly, although women reported higher preoperative levels of emotional distress than men, preoperative anxiety and depression scores were better predictors of severe postoperative pain among men than women, throughout the postoperative test period.

Conclusions

This study underlines the importance of considering sex and psychosocial factors, as well as their interaction, in understanding postsurgical pain trajectories.

A Qualitative Systematic Review of Effects of Provider Characteristics and Nonverbal Behavior on Pain, and Placebo and Nocebo Effects

Background: Previous research has indicated that the sex, status, and nonverbal behaviors of experimenters or clinicians can contribute to reported pain, and placebo and nocebo effects in patients or research participants. However, no systematic review has been published. Objective: The aim of this study was to investigate the effects of experimenter/clinician characteristics and nonverbal behavior on pain, placebo, and nocebo effects. Methods: Using EmBase, Web of Knowledge, and PubMed databases, several literature searches were conducted to find studies that investigated the effects of the experimenter's/clinician's sex, status, and nonverbal behaviors on pain, placebo, and nocebo effects. Results: Thirty-four studies were included, 20 on the effects of characteristics of the experimenter/clinician, 11 on the role of nonverbal behaviors, and 3 on the effects of both nonverbal behaviors and characteristics of experimenters/clinicians on pain and placebo/nocebo effects. There was a tendency for experimenters/clinicians to induce lower pain report in participants of the opposite sex. Furthermore, higher confidence, competence, and professionalism of experimenters/clinicians resulted in lower pain report and higher placebo effects, whereas lower status of experimenters/clinicians such as lower confidence, competence, and professionalism generated higher reported pain and lower placebo effects. Positive nonverbal behaviors (e.g., smiling, strong tone of voice, more eye contact, more leaning toward the patient/participant, and more body gestures) contributed to lower reported pain and higher placebo effects, whereas negative nonverbal behaviors (i.e., no smile, monotonous tone of voice, no eye contact, leaning backward from the participant/patient, and no body gestures) contributed to higher reported pain and nocebo effects. Conclusion: Characteristics and nonverbal behaviors of experimenters/clinicians contribute to the elicitation and modulation of pain, placebo, and nocebo effects.

Evaluating psychosocial contributions to chronic pain outcomes

The biopsychosocial model of pain dominates the scientific community's understanding of chronic pain. Indeed, the biopsychosocial approach describes pain and disability as a multidimensional, dynamic integration among physiological, psychological, and social factors that reciprocally influence one another. In this article, we review two categories of studies that evaluate the contributions of psychosocial factors to the experience of chronic pain. First, we consider general psychosocial variables including distress, trauma, and interpersonal factors. Additionally, we discuss pain-specific psychosocial variables including catastrophizing, expectations, and pain-related coping. Together, we present a diverse array of psychological, social, and contextual factors and highlight the need to consider their roles in the development, maintenance, and treatment of chronic pain conditions.

Sex, Gender, and Orofacial Pain

This review examines gender prevalence in orofacial pain to elucidate underlying factors that can explain such differences. This review highlights how gender affects (1) the association of hormonal factors and pain modulation; (2) the genetic aspects influencing pain sensitivity and pain perception; (3) the role of resting blood pressure and pain threshold; and (4) the impact of sociocultural, environmental, and psychological factors on pain.

Pain catastrophizing, neuroticism, fear of pain, and anxiety: Defining the genetic and environmental factors in a sample of female twins

The objective of the present study was to establish the heritability of pain catastrophizing and its subdomains of helplessness, magnification, and rumination and to further explore the genetic and environmental sources that may contribute to pain catastrophizing as well as to its commonly reported psycho-affective correlates, including neuroticism, anxiety sensitivity, and fear of pain. N = 2,401 female twin individuals from the TwinsUK registry were subject to univariate and multivariate twin analyses. Well validated questionnaires including the Pain Catastrophizing Scale, the Pain Anxiety Symptom Scale, the Ten Item Personality Index, and the Anxiety Sensitivity Index were used to assess the study variables. Moderate estimates of heritability for pain catastrophizing (36%) and the three subdomains of helplessness (35%), rumination (27%), and magnification (36%) were detected. The high correlations observed between the three subdomains were explained mainly by overlapping genetic factors, with a single factor loading on all three phenotypes. High genetic correlations between pain catastrophizing and its psycho-affective correlates of fear of pain and anxiety sensitivity were found, while the genetic overlap between neuroticism and pain catastrophizing was low. Each measure of negative affect demonstrated relatively distinct environmental contributing factors, with very little overlap. This is the first study to show shared genetic factors in the observed association between pain catastrophizing and other measures of negative affect. Our findings provide deeper insight into the aetiology of pain catastrophizing and confirm that it is at least partially distinct from other measures of negative affect and personality that may influence the development and treatment of chronic pain conditions. Further research in males is warranted to check the comparability of the findings.

Neuroticism and pain catastrophizing aggravate response to pain in healthy adults: an experimental study

Background

The aim of this study was to investigate the association between neuroticism, pain catastrophizing, and experimentally induced pain threshold and pain tolerance in a healthy adult sample from two regions of the country of Croatia: the island of Korcula and city of Split.

Methods

A total of 1,322 participants were enrolled from the Island of Korcula (n = 824) and the city of Split (n = 498). Participants completed a self-reported personality measure Eysenck Personality Questionnaire (EPQ) and pain catastrophizing questionnaire Pain Catastrophizing Scale (PCS), followed by a mechanical pain pressure threshold and tolerance test. We have explored the mediating role of catastrophizing in the relationship between neuroticism and pain intensity.

Results

The results showed that pain catastrophizing partially mediated the relationship between neuroticism and pain intensity, suggesting the importance of pain catastrophizing in increasing vulnerability to pain. The results also indicated gender-related differences, marked by the higher pain threshold and tolerance in men.

Conclusions

This study adds to the understanding of the complex interplay between personality and pain, by providing a better understanding of such mechanisms in healthy adults.

Do Correlates of Pain-Related Stoicism and Cautiousness Differ in Younger and Older People With Advanced Cancer?

Age differences are not evident in pain-related stoicism and cautiousness in people with cancer pain. Little is known about the factors associated with these pain-related attitudes or age-related patterns in these associations. The present cross-sectional study investigated the biopsychosocial correlates of the attitudes in younger and older patients with advanced cancer. Pain-related stoicism (fortitude, concealment, superiority) and cautiousness (self-doubt, reluctance) were assessed using the Pain Attitudes Questionnaire-Revised (PAQ-R). Participants, 155 younger (younger than 60 years old) and 114 older (60 years old or older) patients with advanced cancer completed the PAQ-R and measures of sociodemographic and medical characteristics, pain intensity, cognitive-affective pain-related responses, physical functioning, psychological distress and well-being, and psychosocial functioning. Backwards regression analyses identified correlates for each PAQ-R factor separately for younger and older patients. Activity engagement was a frequent correlate, but its relationship with concealment was the only association common to both age groups. Younger and older patients exhibited different avoidance-related constructs suggesting relational challenges in the former group (avoidant attachment) and intrapersonal fear in the latter (cognitive avoidance). Medical correlates also showed age differences: younger patients showed symptom-focused correlates, whereas older patients showed aging-related correlates. Findings support a biopsychosocial framework of cancer-pain adaptation incorporating a lifespan-developmental perspective.

PERSPECTIVE

To our knowledge, this article is the first to identify biopsychosocial correlates of stoic and cautious attitudes toward cancer pain in younger and older patients with advanced cancer. Findings highlight possible age-related motivations for greater pain-related stoicism or cautiousness and can potentially inform interventions addressing challenges in cancer-pain adaptation in advanced cancer.

Sex-Specific Effects of Gender Identification on Pain Study Recruitment

Epidemiological, clinical, and laboratory studies show sex differences in pain responses, with women more sensitive to nociceptive stimulation and more vulnerable to long-term pain conditions than men. Because of evidence that men are culturally reinforced for the ability to endure (or under-report) pain, some of these findings might be explained by sociocultural beliefs about gender-appropriate behavior. One potential manifestation of these effects might be differential participation in pain studies, with men adhering to stereotypical masculine roles viewing participation as a way to demonstrate their masculinity. To test this possibility, we assessed gender identification in 137 healthy participants. At the end of the assessment, they were asked if they would like to participate in other research studies. Interested participants were then asked to participate in a study involving administration of pain-evoking stimulation. We compared individuals who agreed to participate in the pain study with those who declined. We observed a significant Sex × Participation interaction in masculine gender identification, such that men (but not women) who agreed to participate identified significantly more with masculine gender. Among masculine gender traits examined, we found that high levels of aggression and competitiveness were the strongest predictors of pain study participation. Our results suggest that men in pain studies might have higher levels of masculine gender identification than the wider male population. Taken together with previous findings of lower levels of pain sensitivity (or reporting) in masculine-identifying male participants, these results suggest an explanation for some of the sex-related differences observed in pain responses.

PERSPECTIVE

To examine whether sex and gender affect willingness to participate in pain studies, we assessed gender identification in men and women, then attempted to recruit them to participate in a pain study. Men who agree to participate in pain studies are significantly higher in masculine gender identification than men who decline to participate or women who agree to participate. Men who agreed to participate were rated particularly high in aggressiveness and competitiveness.

Influence of Catastrophizing and Personality Traits on Recalled Ratings of Acute Pain Experience in Healthy Young Adults

Objective

To investigate whether pain catastrophizing and personality traits bias recalled ratings of acute pain in an experimental tonic pain model.

Subjects and Setting

Fifty-six undergraduates (14 males) recruited from the University of Peradeniya (mean age 21.7 ± 0.8 SD years).

Design and Methods

Participants completed the Pain Catastrophizing Scale and the Eysenck Personality Questionnaire. They were subjected to two cold pressor tests (dominant and non-dominant hands) and pain threshold, maximum pain intensity, and pain tolerance were recorded. One-week later, the maximum pain intensities of both hands were recalled and percentage distortions in recalling were calculated. Based on a 180 s cutoff, two participants were considered pain-insensitive during the test and were excluded from the analysis.

Results

The maximum pain intensity was recalled with a moderate accuracy (Intraclass Correlation Coefficients = 0.68 for dominant and 0.59 for non-dominant hands). Hierarchical multiple regression analyses revealed that maximum pain intensity ( P  < 0.001) and pain catastrophizing ( P  < 0.001) contributed significantly to recalled pain intensity, and only pain catastrophizing contributed significantly ( P  < 0.001) to percentage distortion in recalling with positive β-coefficients. Participants who consistently overrated pain for both hands in recalling scored significantly higher on catastrophizing ( P  < 0.001).

Conclusion

This study demonstrated that memory for painful events in healthy subjects was reasonably accurate over a period of 1 week. Pain catastrophizing biased pain recall, whereas among personality traits only neuroticism exhibited a weak positive association with the recalled ratings.

Efficacy of different methods to reduce pain during debonding of orthodontic brackets

OBJECTIVE

To determine pain during debonding and the effects of different pain control methods, gender, and personal traits on the pain experience.

MATERIALS AND METHODS

Patients who had fixed orthodontic treatment with metal brackets, but no surgical treatment or craniofacial deformity, were included. Sixty-three patients (32 female, aged 17.2 ± 2.9 years; 31 male aged, 17.2 ± 2.5 years) were allocated to three groups (n = 21) according to the pain control method: finger pressure, elastomeric wafer, or stress relief. Pain experience for each tooth was scored on a visual analogue scale (VAS), and general responses of participants to pain were evaluated by Pain Catastrophizing Scale (PCS). Multiple linear regression analysis, the Mann Whitney U-test, and Spearman's rank correlation coefficient analysis were used to analyze the data.

RESULTS

When the VAS scores were adjusted, finger pressure caused a 47% reduction overall, 56% in lower elastomer wafer total, 59% in lower right arch, 62% in lower left, and 62% in lower anterior compared with the elastomeric wafer. In the elastomer wafer group, upper and lower anterior scores were higher than posterior scores, respectively. Females had higher VAS (lower left and anterior) and total PCS scores than males. Regardless of the pain control method, total PCS scores were correlated with total (r = .254), upper total (r = .290), right (r = .258), left (r = .244), and posterior (r = .278) VAS scores.

CONCLUSIONS

The stress relief method showed no difference when compared with the other groups. Finger pressure was more effective than the elastomeric wafer in the lower jaw. Higher pain levels were recorded for the anterior regions with the elastomeric wafer. Females and pain catastrophizers gave higher VAS scores.

Quantitative and Qualitative Responses to Topical Cold in Healthy Caucasians Show Variance between Individuals but High Test-Retest Reliability

Increased sensitivity to cold may be a predictor of persistent pain, but cold pain threshold is often viewed as unreliable. This study aimed to determine the within-subject reliability and between-subject variance of cold response, measured comprehensively as cold pain threshold plus pain intensity and sensation quality at threshold. A test-retest design was used over three sessions, one day apart. Response to cold was assessed at four sites (thenar eminence, volar forearm, tibialis anterior, plantar foot). Cold pain threshold was measured using a Medoc thermode and standard method of limits. Intensity of pain at threshold was rated using a 10cm visual analogue scale. Quality of sensation at threshold was quantified with indices calculated from subjects' selection of descriptors from a standard McGill Pain Questionnaire. Within-subject reliability for each measure was calculated with intra-class correlation coefficients and between-subject variance was evaluated as group coefficient of variation percentage (CV%). Gender and site comparisons were also made. Forty-five healthy adults participated: 20 male, 25 female; mean age 29 (range 18–56) years. All measures at all four test sites showed high within-subject reliability: cold pain thresholds r = 0.92–0.95; pain rating r = 0.93–0.97; McGill pain quality indices r = 0.87–0.85. In contrast, all measures showed wide between-subject variance (CV% between 51.4% and 92.5%). Upper limb sites were consistently more sensitive than lower limb sites, but equally reliable. Females showed elevated cold pain thresholds, although similar pain intensity and quality to males. Females were also more reliable and showed lower variance for all measures. Thus, although there was clear population variation, response to cold for healthy individuals was found to be highly reliable, whether measured as pain threshold, pain intensity or sensation quality. A comprehensive approach to cold response testing therefore may add validity and improve acceptance of this potentially important pain measure.

Cognitive processes in comorbid poor sleep and chronic pain

We examined the unique and shared contributions of pain catastrophizing, cognitive pre-sleep arousal, and somatic pre-sleep arousal, to the prediction of insomnia severity in chronic pain. Forty-eight adults with chronic pain completed self-report measures of these study variables, health, and mood. Hierarchical regression showed that pain catastrophizing accounted for unique variance in insomnia severity, independent of pain intensity, depression, restless legs symptoms, and demographics. However, when cognitive and somatic pre-sleep arousal were also taken into account, the significance of cognitive pre-sleep arousal rendered pain catastrophizing non-significant. We identify research and clinical implications of this study.

The fear-avoidance model of chronic pain: assessing the role of neuroticism and negative affect in pain catastrophizing using structural equation modeling

BACKGROUND

Previous research on the fear-avoidance model (FAM) of chronic pain suggests that the personality traits of neuroticism and negative affect (NA) influence pain catastrophizing. However, the mechanisms of their influence on pain catastrophizing remain unclear.

PURPOSE

This study examined four possible models of relationships between neuroticism, NA, and pain catastrophizing within the FAM framework using structural equation modeling.

METHOD

A total of 401 patients with chronic musculoskeletal pain completed measures of neuroticism, NA, three core FAM components (pain catastrophizing, pain-related fear, and pain anxiety), and adjustment outcomes (pain-related disability and depression).

RESULTS

Regression analyses refuted the possibility that neuroticism and NA moderated each other's effect on pain catastrophic thoughts (p > 0.05). Results of structural equation modeling (SEM) evidenced superior data-model fit for the collapsed models in which neuroticism and NA were two secondary traits underlying a latent construct, negative emotion (disability: comparative fit index (CFI) = 0.93; depression: CFI = 0.91).

CONCLUSION

The results offer preliminary evidence that patients presenting with more neurotic symptom and heightened NA probably elicit more catastrophic thoughts about pain.

Prevalence and correlation between TMD based on RDC/TMD diagnoses, oral parafunctions and psychoemotional stress in Polish university students

The aim of the study was to assess the prevalence of temporomandibular disorders (TMD) and oral parafunctions, as well as their correlation with psychoemotional factors in Polish university students. The research was conducted in a group of 456 students (N = 456). The examination form comprised of two parts: survey and clinical examination. The research diagnostic criteria for temporomandibular disorders (RDC/TMD) was used in order to assess TMD. Symptoms of TMD were observed in 246 (54%) students after clinical examination. The largest group involved students with disc displacement (women: 132, 29%; men: 70, 15%). Women (164; 36%) suffered more frequently than men (82; 18%) from problems related to the stomatognathic system (P < 0.05), described themselves as easily excitable and emotionally burdened, and reported symptoms as tightness of the facial and neck muscles (P < 0.05). In 289 (64%) students intraoral symptoms concerning occlusal parafunctions were observed. In 404 (89%) examined students, nonocclusal parafunctions were recorded. A significant correlation between TMD and psychoemotional problems could be detected. TMD symptoms more often concern women. Emotional burden and excitability are factors predisposing muscular disorders.

The socially evaluated cold-pressor test (SECPT) for groups: effects of repeated administration of a combined physiological and psychological stressor

The combined administration of physiological (cold pressor) and psychological (social-evaluative threat) stressors, as in the socially evaluated cold pressor test (SECPT; Schwabe et al., 2008) activates the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis. Thus far, the SECPT has been administered exclusively to individual participants, which requires substantial personal effort and time. Therefore, the aim of the present study was to investigate whether and to what extent cardiovascular parameters (SNS) and salivary cortisol concentrations (HPA axis) are affected over the course of repeated SECPT administration in a group design. The SECPT was conducted in groups of seven or more persons and repeated twice with a 24-h interval between each administration. During the stress test, the participants (n=61) were videotaped and observed continuously while they immersed their hands into ice-cold (1 °C, experimental group) or room-temperature (20 °C, control group) water. Blood pressure, heart rate, salivary cortisol concentration, and subjective stress perception were measured. All of these parameters increased significantly during each of the three stress exposures; in contrast, they remained constant in the control group. Moreover, the heart rate response towards the stressor decreased significantly over the course of the repeated stress exposures and salivary cortisol concentration of the experimental group was elevated before the third SECPT administration. Our results indicate that the group SECPT activates the SNS and the HPA, leading to increased blood pressure, heart rate, and cortisol concentration. Moreover, the repeated administration leads to habituation exclusively of heart rate.

Performance based on sEMG activity is related to psychosocial components: differences between back and abdominal endurance tests

The influence of psychosocial components on back and abdominal endurance tests in patients with persistent non-specific low back pain should be investigated to ensure the correct interpretation of these measures. Three-hundred and thirty-two patients (291 men and 41 women) from 19 to 63years performed an abdominal and back muscle endurance test after completing some psychosocial questionnaires. During the endurance tests, surface electromyography signals of the internal obliques, the external obliques, the lumbar multifidus and the iliocostalis were recorded. Patients were dichotomized as underperformers and good performers, by comparing their real endurance time, to the expected time of endurance derived from the normalized median frequency slope. Independent t-tests were performed to examine the differences on the outcome of the questionnaires. In the back muscle endurance test, the underperformers had significantly lower (p<0.05) scores on some of the physical subscales of the SF-36. The underperformers group of the AE test scored significantly higher on the DRAM MZDI (p=0.018) and on the PCS scale (p=0.020) and showed also significantly lower scores on the SF-36 (p<0.05). Back muscle endurance tests are influenced by physical components, while abdominal endurance tests seem influenced by psychosocial components.

Pain rating schema: three distinct subgroups of individuals emerge when rating mild, moderate, and severe pain

Background

While the validity of pain assessment has been well documented, the underlying schema (ie, organized, preconceived ideas) of how individuals interpret numerical pain ratings is not well understood. This study’s objectives were to examine numerical pain intensity ratings, from (0 to 10 cm on the visual analog scale [VAS]) across multiple severities of commonly experienced acute pain conditions to determine whether the ratings differed between these pain conditions and/or between individuals.

Methods

A community sample (N=365, 66% female) rated their anticipated pain intensity (VAS) for threshold, mild, moderate, severe, and tolerance level, using several common pain conditions: headache, toothache, joint injury, delayed-onset muscle soreness, burns, and “general pain.”

Results

Cluster analysis revealed three subgroups of individuals, suggesting three types of underlying pain rating schema: 1) Low Rating subgroup (low VAS pain intensity ratings across all the pain severity categories); 2) Low/High Rating subgroup (low VAS pain intensity rating for mild, but high VAS pain intensity rating for severe pain); and 3) High Rating subgroup (high VAS pain intensity ratings across all the pain severity categories). Overall, differences between pain conditions were small: muscle soreness pain intensity was consistently rated lower than the other pain types across severities. The highest pain ratings varied between joint injury and general pain, depending on severity level. No effects of sex or current experience of pain were noted.

Conclusion

The results indicate that: 1) three distinct pain schemas were present in this community-based sample, indicating significant variation in how pain scales are utilized and/or interpreted between clusters of individuals; 2) pain ratings vary by condition, but these differences are minor; and 3) pain rating schemas are not significantly different between males and females or between individuals with and without current pain.

Parental risk factors for the development of pediatric acute and chronic postsurgical pain: a longitudinal study

Background

The goal of this longitudinal study was to examine the associations among psychological factors and pain reports of children and their parents over the 12 month period after pediatric surgery.

Materials and methods

Included in the study were 83 children aged 8–18 years undergoing major surgery. In each case, the child and one of their parents completed measures of pain intensity and unpleasantness, psychological function, and functional disability at 48–72 hours, 2 weeks (child only), 6 months, and 12 months after surgery.

Results

The strength of the correlation coefficients between the psychological measures of the parent and their child increased significantly over time. There was a fair level of agreement between parent ratings of child acute and chronic pain (6 months after surgery) and the child’s actual ratings. Parent and child pain anxiety scores 48–72 hours after surgery interacted significantly to predict pain intensity, pain unpleasantness, and functional disability levels 2 weeks after discharge from hospital. Parent pain catastrophizing scores 48–72 hours after surgery predicted child pain intensity reports 12 months later.

Conclusion

These results raise the possibility that as time from surgery increases, parents exert greater and greater influence over the pain response of their children, so that by 12 months postsurgery mark, parent pain catastrophizing (measured in the days after surgery) is the main risk factor for the development of postsurgical pain chronicity.

Gender role expectations of pain mediate sex differences in cold pain responses in healthy Libyans

Previous studies found a relationship between response to experimentally-induced pain and scores for the gender role expectations of pain (GREP) questionnaire. Findings were similar in individuals from America, Portugal and Israel suggesting that gender role expectations may be universal. The aim of this study was to translate and validate Arabic GREP using Factor Analysis and to investigate if sex differences to cold-pressor pain in healthy Libyan men and women are mediated through stereotypical social constructs of gender role expectations and/or pain-related anxiety. One hundred fourteen university students (58 women) underwent two cycles of cold pressor pain test to measure pain threshold, tolerance, intensity, and unpleasantness. Participants also completed the Arabic GREP questionnaire and the Pain Anxiety Symptom Scale-Short form (PASS-20). It was found that Libyan men had higher pain thresholds and tolerances than women (mean difference, 95% CI: threshold = 4.69 (s), -0.72 to 10.1, p = 0.005; tolerance = 13.46 (s), 0.5-26.4, p = 0.018). There were significant differences between sexes in 6 out of 12 GREP items (p < 0.004 after Bonferonni adjustment). The results of mediational analysis showed that GREP factors were the mediators of the effects of sex on pain threshold (z = -2.452, p = 0.014 for Self Sensitivity); (z = -2.563, p = 0.01, for Self Endurance) and on pain tolerance (z = -2.538, p = 0.01 for Self Endurance). In conclusion, sex differences in response to pain were mediated by gender role expectations of pain but not pain-related anxiety.

Psychological factors predict local and referred experimental muscle pain: a cluster analysis in healthy adults

BACKGROUND

Recent studies suggest an underlying three- or four-factor structure explains the conceptual overlap and distinctiveness of several negative emotionality and pain-related constructs. However, the validity of these latent factors for predicting pain has not been examined.

METHODS

A cohort of 189 (99 female, 90 male) healthy volunteers completed eight self-report negative emotionality and pain-related measures (Eysenck Personality Questionnaire - Revised, Positive and Negative Affect Schedule, State-Trait Anxiety Inventory, Pain Catastrophizing Scale, Fear of Pain Questionnaire; Somatosensory Amplification Scale, Anxiety Sensitivity Index and Whiteley Index). Using principal axis factoring, three primary latent factors were extracted: general distress, catastrophic thinking and pain-related fear. Using these factors, individuals clustered into three subgroups of high, moderate and low negative emotionality responses. Experimental pain was induced via intramuscular acidic infusion into the anterior tibialis muscle, producing local (infusion site) and/or referred (anterior ankle) pain and hyperalgesia.

RESULTS

Pain outcomes differed between clusters (multivariate analysis of variance and multinomial regression), with individuals in the highest negative emotionality cluster reporting the greatest local pain (p = 0.05), mechanical hyperalgesia (pressure pain thresholds; p = 0.009) and greater odds (2.21 odds ratio) of experiencing referred pain when compared to the lowest negative emotionality cluster.

CONCLUSION

Our results provide support for three latent psychological factors explaining the majority of the variance between several pain-related psychological measures, and that individuals in the high negative emotionality subgroup are at increased risk for (1) acute local muscle pain; (2) local hyperalgesia; and (3) referred pain using a standardized nociceptive input.

Changes in pain catastrophizing predict later changes in fibromyalgia clinical and experimental pain report: cross-lagged panel analyses of dispositional and situational catastrophizing

Introduction

Fibromyalgia (FM), characterized by wide-spread diffuse pain and sensory abnormalities, is associated with elevated indices of distress and pain-related catastrophizing compared to both pain-free samples and those with chronic pain conditions. Catastrophizing is a pervasive negative mental set, and is a strong predictor of negative pain-related outcomes such as clinical pain intensity, and physical disability. Situational catastrophizing, measured in the context of experimentally-induced pain, is strongly related to enhanced pain sensitivity, a core aspect of the pathophysiology of fibromyalgia. However, little is known regarding the temporal course of the association between catastrophizing and pain-related "outcomes". Most studies involve only static assessments of pain and catastrophizing at a single time point, which provides little insight into the direction of the observed associations. We sought to investigate the temporal relationships between catastrophizing and indices of both clinical pain (substudy 1) and experimentally-induced pain (substudy 2) in a larger randomized controlled longitudinal trial.

Methods

Fifty-seven patients with FM completed catastrophizing, depression, and pain questionnaires as well as laboratory cold pressor pain testing at baseline, post-intervention and three month follow-up during a lifestyle physical activity study. Cross-lagged panel analyses were used to address these temporal relationships.

Results

In substudy 1, analyses revealed that pre-to-post changes in dispositional catastrophizing ratings prospectively accounted for unique variance in subsequent post-to-follow-up changes in clinical pain ratings (p = 0.005), while pre-to-post changes in pain ratings did not account for unique variance in post-to-follow-up changes in catastrophizing ratings. An identical pattern was observed experimentally in substudy 2, with pre-to-post changes in situational catastrophizing ratings prospectively accounting for unique variance in subsequent post-to-follow-up changes in experimental pain ratings (p = 0.014), while pre-to-post changes in pain ratings did not account for unique variance in post-to-follow-up changes in catastrophizing ratings. Specifically, initial alterations in catastrophizing were associated with subsequent alterations in clinical and experimentally induced pain. Controlling for levels of depression did not affect the results.

Conclusions

These findings provide empirical evidence that catastrophizing processes might precede and contribute to subsequent alterations in the pain experience for FM patients.

Trial Registration

clinicaltrials.gov: NCT00383084.

Effects of ethnicity and gender role expectations of pain on experimental pain: a cross-cultural study

BACKGROUND

Gender role expectations of pain (GREP) have been shown to mediate sex differences in experimental pain. Few studies have investigated the role of ethnicity in shaping GREP. The aim of this study was to examine interactions between ethnicity and GREP on experimentally induced pressure and ischaemic pain in Libyan and white British students in their respective countries.

METHODS

Libyan (n = 124) and white British (n = 51) students completed a GREP questionnaire and their response to experimental pain was measured. Blunt pressure pain threshold (PPT) was measured over the 1st interosseous muscle using algometry. Pain intensity and pain unpleasantness (100 mm visual analogue scale) were measured at 1-min intervals during a submaximal effort tourniquet test on the forearm.

RESULTS

Multivariate analysis of variance detected significant effects for Sex and Ethnicity on pain measurements. Men had higher PPTs than women (p < 0.001). Libyans had higher PPTs than white British participants (p < 0.001). There were significant effects for Sex and Ethnicity for pain intensity ratings (p < 0.01) but no significant differences between the sexes in pain unpleasantness (p > 0.05). Libyan participants had higher pain intensity (p < 0.01) and pain unpleasantness (p < 0.05) ratings compared with white British participants. There were effects for Sex and Ethnicity for all GREP dimensions. Libyan participants exhibited stronger stereotypical views in GREP than white British participants (p < 0.001).

CONCLUSIONS

GREP was the mediator of sex but not ethnic differences in pain report, suggesting that gender stereotypical attitudes to pain account for differences in pain expression between men and women.

Gender role affects experimental pain responses: a systematic review with meta-analysis

Gender role refers to the culturally and socially constructed meanings that describe how women and men should behave in certain situations according to feminine and masculine roles learned throughout life. The aim of this meta-analysis was to evaluate the relationship between gender role and experimental pain responses in healthy human participants. We searched computerized databases for studies published between January 1950 and May 2011 that had measured gender role in healthy human adults and pain response to noxious stimuli. Studies were entered into a meta-analysis if they calculated a correlation coefficient (r) for gender role and experimental pain. Searches yielded 4465 'hits' and 13 studies were eligible for review. Sample sizes were 67-235 participants and the proportion of female participants was 45-67%. Eight types of gender role instrument were used. Meta-analysis of six studies (406 men and 539 women) found a significant positive correlation between masculine and feminine personality traits and pain threshold and tolerance, with a small effect size (r = 0.17, p = 0.01). Meta-analysis of four studies (263 men and 297 women) found a significant negative correlation between gender stereotypes specific to pain and pain threshold and tolerance, with a moderate effect size (r = -0.41, p < 0.001). In conclusion, individuals who considered themselves more masculine and less sensitive to pain than the typical man showed higher pain thresholds and tolerances. Gender stereotypes specific to pain scales showed stronger associations with sex differences in pain sensitivity response than masculine and feminine personality trait scales.

A systematic literature review of 10 years of research on sex/gender and experimental pain perception - part 1: are there really differences between women and men?

The purpose of this systematic review was to summarize and critically appraise the results of 10 years of human laboratory research on pain and sex/gender. An electronic search strategy was designed by a medical librarian and conducted in multiple databases. A total of 172 articles published between 1998 and 2008 were retrieved, analyzed, and synthesized. The first set of results (122 articles), which is presented in this paper, examined sex difference in the perception of laboratory-induced thermal, pressure, ischemic, muscle, electrical, chemical, and visceral pain in healthy subjects. This review suggests that females (F) and males (M) have comparable thresholds for cold and ischemic pain, while pressure pain thresholds are lower in F than M. There is strong evidence that F tolerate less thermal (heat, cold) and pressure pain than M but it is not the case for tolerance to ischemic pain, which is comparable in both sexes. The majority of the studies that measured pain intensity and unpleasantness showed no sex difference in many pain modalities. In summary, 10 years of laboratory research have not been successful in producing a clear and consistent pattern of sex differences in human pain sensitivity, even with the use of deep, tonic, long-lasting stimuli, which are known to better mimic clinical pain. Whether laboratory studies in healthy subjects are the best paradigm to investigate sex differences in pain perception is open to question and should be discussed with a view to enhancing the clinical relevance of these experiments and developing new research avenues.