Demographic Predictors of Pain Sensitivity: Results From the OPPERA Study

Minimum clinically important difference and substantial clinical benefit in patients with chronic temporomandibular disorders

BACKGROUND

Research on temporomandibular disorder (TMD) responsiveness is scarce and limited regarding patients' representativeness.

OBJECTIVE(S)

This study aimed to estimate minimum clinically important difference (MCID) and substantial clinical benefit (SCB) among a large and diverse patient population regarding sex and age.

METHODS

In this study, 162 patients participated from five hospitals. MCID and SCB in pain, functional disability and quality of life were examined with anchor-based methods. Patients' global impression of change was used as the anchor. Area under the curve (AUC) values were determined for testing accuracy. Changes from baseline and coefficient of variation by responsiveness status were calculated to explain the results of accuracy.

RESULTS

SCB was estimated to be 2.18 for the numeric rating scale (NRS) for pain (AUC: 0.80 [95% CI: 0.72-0.88]) in all patients and 2.50 in women (AUC: 0.81 [95% CI: 0.71-0.89]). The estimated SCB of NRS for discomfort (1.50) and Jaw Functional Limitation Scale for mastication (1.35) had wide CIs for AUCs. Likewise, the estimated MCIDs of NRS for pain (0.80) and NRS for discomfort (1.50) had wide CIs for AUCs. Among non-responders who did not achieve the MCID of NRS for pain, the coefficient of variation was very high for all outcomes other than the NRS for pain.

CONCLUSION

This study investigated the responsiveness of patients with TMD using a large and diverse patient sample. SCB in pain decrease can be used to assess the responsiveness of patients with TMD. Composite outcomes should be developed to estimate MCID.

The normative values of pain thresholds in healthy Taiwanese

OBJECTIVE

Quantitative sensory testing is widely used in clinical and research settings to assess the sensory functions of healthy subjects and patients. It is of importance to establish normative values in a healthy population to provide reference for studies involving patients. Given the absence of normative values for pain thresholds in Taiwan, the aim of this study was to report the normative values for future reference in the Taiwanese population and compare the differences between male and female participants.

METHODS

Healthy adults without any chronic or acute pain condition were recruited. The pain thresholds were assessed over the cephalic (supraorbital area and masseter muscle) and extracephalic (medio-volar forearm and thenar eminence) areas. The heat, cold, mechanical punctate, and pressure pain thresholds were measured with a standardized protocol. Comparisons between male and female participants were performed.

RESULTS

One hundred and thirty healthy participants (55 males: 30.4 ± 7.4 years; 75 females: 30.5 ± 8.1 years) finished the assessments. Male participants were less sensitive to mechanical stimuli, including pressure over masseter muscle (male vs. female: 178.5 ± 56.7 vs. 156.6 ± 58.4 kPa, p = .034) and punctate over medio-volar forearm (male vs. female: 116.4 ± 45.2 vs. 98.7 ± 65.4 g, p = .011), compared to female participants. However, female participants were less sensitive to cold stimuli, indicated by lower cold pain thresholds over the supraorbital area (male vs. female: 18.6 ± 8.4 vs. 13.6 ± 9.3°C, p = .004), compared to male participants. No significant differences were found between sexes in other pain threshold parameters.

CONCLUSIONS

We provided the normative values of healthy male and female adults in Taiwan. This information is crucial for comparison in future pain-related studies to identify potential hypoalgesia or hyperalgesia of tested subjects.

The Problem of Pain in Rheumatology: Variations in Case Definitions Derived From Chronic Pain Phenotyping Algorithms Using Electronic Health Records

OBJECTIVE

The aim of this study was to investigate and compare different case definitions for chronic pain to provide estimates of possible misclassification when researchers are limited by available electronic health record and administrative claims data, allowing for greater precision in case definitions.

METHODS

We compared the prevalence of different case definitions for chronic pain (N = 3042) in patients with autoimmune rheumatic diseases. We estimated the prevalence of chronic pain based on 15 unique combinations of pain scores, diagnostic codes, analgesic medications, and pain interventions.

RESULTS

Chronic pain prevalence was lowest in unimodal pain phenotyping algorithms: 15% using analgesic medications, 18% using pain scores, 21% using pain diagnostic codes, and 22% using pain interventions. In comparison, the prevalence using a well-validated phenotyping algorithm was 37%. The prevalence of chronic pain also increased with the increasing number (bimodal to quadrimodal) of phenotyping algorithms that comprised the multimodal phenotyping algorithms. The highest estimated chronic pain prevalence (47%) was the multimodal phenotyping algorithm that combined pain scores, diagnostic codes, analgesic medications, and pain interventions. However, this quadrimodal phenotyping algorithm yielded a 10% overestimation of chronic pain compared to the well-validated algorithm.

CONCLUSION

This is the first empirical study to our knowledge that shows that established common modes of phenotyping chronic pain can lead to substantially varying estimates of the number of patients with chronic pain. These findings can be a reference for biases in case definitions for chronic pain and could be used to estimate the extent of possible misclassifications or corrections in using datasets that cannot include specific data elements.

The level of agreement between the numerical rating scale and visual analogue scale for assessing pain intensity in adults with chronic pain

The numerical rating scale and visual analogue scale are used to quantify pain intensity. However, it has not yet been explored whether these scores are interchangeable in adults with chronic pain. Data from the prospective multicentre cross-sectional INTERVAL study were used to evaluate the one-dimensionality and agreement between numerical rating scale scores and visual analogue scale scores in adults with chronic pain. Pain intensity scores using the numerical rating scale and visual analogue scale were provided by 366 patients with chronic pain for current, average, minimal and maximal pain. To evaluate whether pain intensity scales are completed in accordance with each other, the proportion of patients who satisfied the following condition was calculated: minimal pain intensity ≤ maximal pain intensity. A factor analysis confirmed the one-dimensionality of the pain measures. A significant difference was found between numerical rating scale and visual analogue scale scores for average, current, minimum and maximum pain. Intra-class correlation coefficient estimates ranged from 0.739 to 0.858 and all measures failed to show sufficient and acceptable agreement at the 95% level. The strength of agreement between pain severity categories was classified as 'moderate' for average and minimal pain and 'substantial' for current and maximal pain. The proportion of patients who scored minimal pain ≤ maximal pain was 97.5% for the numerical rating scale and 89.5% for the visual analogue scale. This study failed to show an acceptable agreement between the numerical rating scale and visual analogue scale when pain intensity was rated by adults with chronic pain, despite showing both scales measure the same information.

Biomechanical properties of masseter muscle assessed through myotonometry in patients with temporomandibular disorder treated with ultrasound therapy: a randomized comparative study

BACKGROUND

The aim of the study was to make an objective quantitative assessment of effectiveness of procedures with the use of a therapeutic dose of ultrasounds in this nosological entity, in connection with improved biomechanical properties and alleviation of pain experienced in masseter muscles.

METHODS

The study included 40 patients with temporomandibular disorder. In group 1 (N.=20) ultrasound therapy (1.2 W/cm2) was carried out, while in group 2 (N.=20) sham therapy was applied. A total of 10 procedures were performed. Myotonometric measurements and assessment of pain intensity were carried out before treatment and after the completion of procedures.

RESULTS

The analysis revealed a significant difference (P=0.011) between the values of decrement (D) measured on day 0 (2.08±0.45 [log]) and day 4 (1.80±0.55 [log]) in group 1. In group 2 no statistically significant differences were noted between the results obtained on consecutive days of the therapeutic cycle. A statistically significant difference in values of decrement (D) between group 1 (1.80±0.55 [log]) and group 2 (2.23±0.51 [log]) was noted on day 4 of the experiment (P=0.021). Both in group 1 and in group 2, a statistically significant reduction of pain intensity (VAS Scale) was obtained.

CONCLUSIONS

The masseter muscle was more elastic during ultrasound therapy. However, the effect was transient. The analgesic effect was also observed in the control group; therefore, a placebo effect cannot be excluded.

Effect of photobiomodulation on postoperative endodontic pain: A systematic review of clinical trials

Background

This review aims to perform a complete evaluation of the impact of photobiomodulation (PMB) on postoperative endodontic pain.

Materials and Methods

The PRISMA checklist was used to perform this systematic review. The electronic databases were searched, including Google Scholar, PubMed, and Embase. Sixty-three papers were obtained through a main electronic search and a hand search. Nine trials met the criteria after screening the titles, abstracts, and/or full texts.

Results

Seven out of nine studies showed that PMB has a significant impact on relieving postoperative endodontic pain, with no statistically significant difference in the severity of pain between the laser and control groups in the two remaining studies. In addition, eight studies showed no adverse effects, indicating that we can remove the adverse effects of drugs such as nonsteroidal anti-inflammatory drugs. However, one study showed evidence of the consequences of PMB application on teeth with symptomatic irreversible pulpitis. Therefore, it can be concluded that PMB should not be used in teeth with pain because of irreversible pulpitis.

Conclusion

Although there is some understanding from a cellular viewpoint of the effects of PMB, there is still some uncertainty about whether these cell-level modifications impact reducing the postendodontic pain.

Perception of Pain Expression Among Surgical Patients and Families from Three Ethnic Groups of a Nation: A Multicenter Qualitative Study

Background

Despite its universal nature; perception, coping, responses, treatment options, and overall experiences of pain are influenced by biopsychosocial factors to various extents. Pain perception, expression, and control are progressively learned behaviors among members of a society and are culture-specific. Effects of ethnicity-related culture (ethnoculture) on pain experience in a broader context have increasingly been reported. However, evidence from ethnoculturally diverse groups of a nation, particularly based on surgical patients, is limited. Therefore, as a qualitative research effort of a broader project aimed at assessing ethnocultural determinants of surgical pain management, this study explored the perception of ethnoculturally diverse patients and families about expressing surgical disease-related pain.

Methods

This study follows subjectivist-interpretivist philosophical assumptions as an underpinning research paradigm. We purposively selected 11 patients for in-depth interviews and 12 patients' family members for focus group discussions in three hospitals of ethnic-based regions of Ethiopia. In the phenomenological frame, thematic analysis was employed.

Finding

Ethnocultural background influences how individuals express and respond to pain according to emergent themes of finding- Pain and overlooked cultural influence, Pain expressiveness in cultural context, Stereotypes of pain expressiveness, and Bravehood through stoic response. Pain feelings are commonly hidden where the domestic culture values stoic response to pain compared to ethnoculture where pain expressiveness is encouraged.

Conclusion

Individuals can express and respond to pain differently due to ethnocultural diversity within a nation. Researchers and clinicians should consider cultural context while applying the prevailing one-size-fits-all pain assessment tools among surgical patients of a nation with ethnocultural diversity.

Forced mouth opening induces post-traumatic hyperalgesia and associated peripheral sensitization after temporomandibular joints injury in mice

Temporomandibular disorder (TMD) is the most prevalent painful condition in the craniofacial area. The pathophysiology of TMD is not fully understood, and it is necessary to understand pathophysiology underlying painful TMD conditions to develop more effective treatment methods. Recent studies suggested that external or intrinsic trauma to TMJ is associated with chronic TMD in patients. Here, we investigated the effects of the TMJ trauma through forced-mouth opening (FMO) in mice to determine pain behaviors and peripheral sensitization of trigeminal nociceptors. FMO increased mechanical hyperalgesia assessed by von Frey test, spontaneous pain-like behaviors assessed by mouse grimace scale, and anxiety-like behaviors assessed by open-field test. In vivo GCaMP Ca 2+ imaging of intact trigeminal ganglia (TG) showed increased spontaneous Ca 2+ activity and mechanical hypersensitivity of TG neurons in the FMO compared to the sham group. Ca 2+ responses evoked by cold, heat, and capsaicin stimuli were also increased. FMO-induced hyperalgesia and neuronal hyperactivities were not sex dependent. TG neurons sensitized following FMO were primarily small to medium-sized nociceptive afferents. Consistently, most TMJ afferents in the TG were small-sized peptidergic neurons expressing calcitonin gene-related peptides, whereas nonpeptidergic TMJ afferents were relatively low. FMO-induced intraneural inflammation in the surrounding tissues of the TMJ indicates potentially novel mechanisms of peripheral sensitization following TMJ injury. These results suggest that the TMJ injury leads to persistent post-traumatic hyperalgesia associated with peripheral sensitization of trigeminal nociceptors.

Secondary analysis: heat and self-report pain sensitivity associate with biological sex and racialized sociocultural group but may not be mediated by anxiety or pain catastrophizing

Introduction

Previous studies have demonstrated associations between sex and racialized group on pain sensitivity and tolerance. We analyzed the association of sex and racialized group on heat pain sensitivity, sensibility to painful suprathreshold mechanical pain (STMP), and pain sensitivity questionnaire (PSQ). We hypothesized that anxiety and pain catastrophizing reported by racialized minority groups and women would mediate enhanced pain sensitivity. Our secondary aim was to evaluate validity of the PSQ in a diverse population.

Methods

Using quantitative sensory testing for painful heat, STMP (forces: 64, 128, 256, and 512 mN), and PSQ, we evaluated pain sensitivity in 134 healthy participants [34 (18 women) Asian, 25 (13 women) Black, and 75 (41 women) White]. We used general linear and linear mixed models to analyze outcomes. We assessed mediation of state and trait anxiety and pain catastrophizing on pain sensitivity.

Results

Racialized minority status was associated with greater heat pain sensitivity (F = 7.63; P = 0.00074) and PSQ scores (F = 15.45; P = 9.84 × 10-7) but not associated with STMP (F = 1.50; P = 0.23). Female sex was associated with greater heat pain sensitivity (F = 4.9; P = 0.029) and lower PSQ (F = 9.50; P = 0.0025) but not associated with STMP (F = 0.0018; P = 0.97). Neither anxiety nor pain catastrophizing mediated associations between sex or racialized group with heat pain threshold or PSQ. Differential experience of individual items (F = 19.87; P = 3.28 × 10-8) limited PSQ face validity in racialized minorities.

Conclusion

Consistent with previous research, sensitivity to painful heat was associated with racialized minority status and female sex. By contrast, there was no significant effect of racialized minority status or female sex on STMP. Some PSQ items are inapplicable to participants from racialized minority groups.

Electronic Health Record Recording of Patient Pain: Challenges and Discrepancies

PURPOSE OF REVIEW

In the present review, various categories of pain, clinician-observed pain scales, and patient-reported pain scales are evaluated to better understand factors that impact patient pain perceptions. Additionally, the expansion of areas that require further research to determine the optimal way to evaluate pain scale data for treatment and management are discussed.

RECENT FINDINGS

Electronic health record (EHR) data provides a starting point for evaluating whether patient predictors influence postoperative pain. There are several ways to assess pain and choosing the most effective form of pain treatment. Identifying individuals at high risk for severe postoperative pain enables more effective pain treatment. However, there are discrepancies in patient pain reporting dependent on instruments used to measure pain and their storage in the EHR. Additionally, whether administered by a physician or another healthcare practitioner, differences in patient pain perception occur. While each scale has distinct advantages and limitations, pain scale data is a valuable therapeutic tool for assisting clinicians in providing patients with optimal pain control. Accurate assessment of patient pain perceptions by data extraction from electronic health records provides a potential for pain alleviation improvement. Predicting high-risk postoperative pain syndromes is a difficult clinical challenge. Numerous studies have been conducted on factors that impact pain prediction. Postoperative pain is significantly predicted by the kind of operation, the existence of prior discomfort, patient anxiety, and age.

Pain management in adult patients with sickle cell disease in the emergency department: how does current practice compare with existing standards of care?

PURPOSE

Sickle cell disease (SCD) is an inherited blood disorder with a natural course punctuated by acute complications including painful vaso-occlusive episodes. The objectives were: (1) to determine what proportion of patients with SCD receive opioids within 30 min of triage as recommended by the current clinical recommendations and quality standard; and (2) to identify facilitators to timely opioid administration for patients with SCD.

METHODS

This was a retrospective observational study. The primary outcome was the proportion of visits in which patients received opioid analgesia within 30 min of triage. Secondary outcomes were time in minutes from triage to any analgesic administration and time from triage to first opioid administration. Patient demographics and ED encounter characteristics were included as potential associated variables.

RESULTS

There were 236 patient visits (by 103 patients) that met inclusion criteria. Patients received opioid analgesia within 30 min of triage in only 5.2% of visits. The median time from triage to opioid analgesia was 80 (IQR = 49.0, 125.5) minutes. Using an order set and receiving opioid analgesia prior to physician assessment were both associated with shorter times to opioid analgesia.

CONCLUSION

Existing recommendations are that opioid analgesia be provided within 30 min of triage for patients with SCD and VOEs. Our data show this target is rarely met, even in a department in which SCD VOEs are a common presenting concern. The association of earlier opioid analgesia with order set use and administration prior to physician assessment highlights potential avenues for improving time to analgesia.

Cluster-Randomized Comparative Effectiveness Trial of Physician-Directed Clinical Decision Support Versus Patient-Directed Education to Promote Appropriate Use of Opioids for Chronic Pain

We compared the effectiveness of physician-directed clinical decision support (CDS) administered via electronic health record versus patient-directed education to promote the appropriate use of opioids by conducting a cluster-randomized trial involving 82 primary care physicians and 951 of their patients with chronic pain. Primary outcomes were satisfaction with patient-physician communication consumer assessment of health care providers and system clinician and group survey (CG-CAHPS) and pain interference patient-reported outcomes measurement information system. Secondary outcomes included physical function (patient-reported outcomes measurement information system), depression (PHQ-9), high-risk opioid prescribing (>90 morphine milligram equivalents per day [≥90 mg morphine equivalent/day]), and co-prescription of opioids and benzodiazepines. We used multi-level regression to compare longitudinal difference-in-difference scores between arms. The odds of achieving the maximum CG-CAHPS score were 2.65 times higher in the patient education versus the CDS arm (P = .044; 95% confidence interval [CI] 1.03-6.80). However, baseline CG-CAHPS scores were dissimilar between arms, making these results challenging to interpret definitively. No difference in pain interference was found between groups (Coef = -0.64, 95% CI -2.66 to 1.38). The patient education arm experienced higher odds of Rx ≥ 90 milligrams morphine equivalent/day (odds ratio = 1.63; P = .010; 95% CI 1.13, 2.36). There were no differences between groups in physical function, depression, or co-prescription of opioids and benzodiazepines. These results suggest that patient-directed education may have the potential to improve satisfaction with patient-physician communication, whereas physician-directed CDS via electronic health records may have greater potential to reduce high-risk opioid dosing. More evidence is needed to ascertain the relative cost-effectiveness between strategies. PERSPECTIVE: This article presents the results of a comparative-effectiveness study of 2 broadly used communication strategies to catalyze dialog between patients and primary care physicians around chronic pain. The results add to the decision-making literature and offer insights about the relative benefits of physician-directed versus patient-directed interventions to promote the appropriate use of opioids.

Feasibility and reliability of a quantitative sensory testing protocol in youth with acute musculoskeletal pain postsurgery or postinjury

ABSTRACT

Quantitative sensory testing (QST) is increasingly used in pediatric chronic pain; however, assessment in youth with acute musculoskeletal (MSK) pain is limited. This study evaluated the feasibility, reliability, and sources of variability of a brief QST protocol in 2 clinical samples of youth with acute MSK pain. Participants were 277 youth (M age = 14.5 years, SD = 2.0, range = 11-18 years, 59% female, 81% non-Hispanic) across 3 geographic study sites who completed a QST protocol assessing pressure and thermal pain sensitivity, temporal summation of pain, and conditioned pain modulation 8 weeks after MSK surgery (n = 100) or within 4 weeks after an acute MSK injury (n = 177). High feasibility was demonstrated by protocol completion rates ranging from 97.5% to 100% for each task, with 95.3% of youth completing all tasks. Reliability was high, with reliability coefficients of >0.97 for 7 out of 8 QST parameters and minimal influence of examiner or participating site effects. Younger youth had lower pressure and heat pain thresholds (11-12 vs 13-18 years, d = -0.80 to -0.56) and cold pain tolerance (d = -0.33). Hispanic youth had higher pressure and heat pain thresholds (d = 0.37-0.45) and pain ratings for cold pain tolerance (d = 0.54) compared with non-Hispanic youth. No significant differences were observed in QST values by sex or personal contextual factors at the time of assessment (momentary pain, menstrual period, use of pain medications). Overall findings demonstrate feasibility of a brief QST protocol with youth with diverse acute MSK pain and data provide initial support for the reliability of this QST protocol for multisite research studies.

Acute Ostracism-Related Pain Sensitization in the Context of Accumulated Lifetime Experiences of Ostracism

Ostracism (ie, being ignored/excluded) is a form of social adversity that powerfully impacts health and well-being. While laboratory research indicates that experimentally manipulated experiences of ostracism impact pain, findings have been mixed. Prior investigations have not considered moderating or main effects of individual histories of ostracism, and have been limited in the scope of their pain testing. In this study, participants without current pain reported lifetime experiences of ostracism prior to a laboratory visit where they were randomized to experience either a single episode of ostracism (ie, acute ostracism) or control condition that was immediately followed by quantitative sensory testing. Results indicate that the experimental effect of a single episode of ostracism on pain ratings, after-sensations, and temporal summation of pain is moderated by lifetime ostracism; no main effects were found. For individuals with histories of more lifetime ostracism, encountering a single episode of ostracism led to greater pain sensitization relative to the control condition, whereas no experimental effect was observed for individuals with little lifetime exposure to ostracism. These findings indicate that acute experiences of ostracism may be accompanied by periods of hyperalgesia for people who are chronically ostracized, implicating ostracism as a potential social moderator of pain sensitization. People who are stigmatized may therefore experience enhanced pain burden with repeated and accumulating experiences of ostracism. PERSPECTIVE: Results suggest that in the context of accumulated lifetime experiences of ostracism, single experiences of ostracism evoke central sensitization. In this way, ostracism may function to trigger central sensitization and shape socially- and societally-determined patterns of pain burden and disparity.

Sensory Neuron-TRPV4 Modulates Temporomandibular Disorder Pain Via CGRP in Mice

Temporomandibular disorder (TMD) pain that involves inflammation and injury in the temporomandibular joint (TMJ) and/or masticatory muscle is the most common form of orofacial pain. We recently found that transient receptor potential vanilloid-4 (TRPV4) in trigeminal ganglion (TG) neurons is upregulated after TMJ inflammation, and TRPV4 coexpresses with calcitonin gene-related peptide (CGRP) in TMJ-innervating TG neurons. Here, we extended these findings to determine the specific contribution of TRPV4 in TG neurons to TMD pain, and examine whether sensory neuron-TRPV4 modulates TMD pain via CGRP. In mouse models of TMJ inflammation or masseter muscle injury, sensory neuron-Trpv4 conditional knockout (cKO) mice displayed reduced pain. Coexpression of TRPV4 and CGRP in TMJ- or masseter muscle-innervating TG neurons was increased after TMJ inflammation and masseter muscle injury, respectively. Activation of TRPV4-expressing TG neurons triggered secretion of CGRP, which was associated with increased levels of CGRP in peri-TMJ tissues, masseter muscle, spinal trigeminal nucleus, and plasma in both models. Local injection of CGRP into the TMJ or masseter muscle evoked acute pain in naïve mice, while blockade of CGRP receptor attenuated pain in mouse models of TMD. These results suggest that TRPV4 in TG neurons contributes to TMD pain by potentiating CGRP secretion. PERSPECTIVE: This study demonstrates that activation of TRPV4 in TG sensory neurons drives pain by potentiating the release of pain mediator CGRP in mouse models of TMJ inflammation and masseter muscle injury. Targeting TRPV4 and CGRP may be of clinical potential in alleviating TMD pain.

Pain phenotyping and investigation of outcomes in physical therapy: An exploratory study in patients with low back pain

Phenotypes have been proposed as a method of characterizing subgroups based on biopsychosocial factors to identify responders to analgesic treatments. This study aimed to, first, confirm phenotypes in patients with low back pain receiving physical therapy based on an a priori set of factors used to derive subgroups in other pain populations. Second, an exploratory analysis examined if phenotypes differentiated pain and disability outcomes at four weeks of physical therapy. Fifty-five participants completed psychological questionnaires and pressure pain threshold (PPT). Somatization, anxiety, and depression domains of the Symptom-Checklist-90-Revised, and PPT, were entered into a hierarchical agglomerative cluster analysis with Ward's method to identify phenotypes. Repeated measures ANOVAs assessed pain ratings and disability by phenotype at four weeks. Three clusters emerged: 1) high emotional distress and pain sensitivity (n = 10), 2) low emotional distress (n = 34), 3) low pain sensitivity (n = 11). As an exploratory study, clusters did not differentiate pain ratings or disability after four weeks of physical therapy (p's>0.05). However, trends were observed as magnitude of change for pain varied by phenotype. This supports the characterization of homogenous subgroups based on a protocol conducted in the clinical setting with varying effect sizes noted by phenotype for short-term changes in pain. As an exploratory study, future studies should aim to repeat this trial in a larger sample of patients.

Exploring the sex differences in conditioned pain modulation and its biobehavioral determinants in healthy adults

BACKGROUND

Females are at greater risk of chronic pain, and exhibit higher pain sensitivity compared to males. However, sex differences in conditioned pain modulation (CPM), a neurophysiological risk factor of chronic pain, are unclear. CPM is influenced by many factors, some of which are sex-dependent. This study explored the sex differences in CPM and its biobehavioral determinants, such as blood pressure responses, physical activity levels, pain catastrophizing scores, and conditioning stimulus intensity, in young, healthy, physically active males and females.

METHODS

Twenty-six males and 24 females completed the CPM test using an electrical pain stimulus and a cold pain stimulus induced via 2 min of cold pressor test. Blood pressure was assessed at baseline and during cold pressor test, whereas cold pain ratings were obtained during cold pressor test to monitor the conditioning stimulus intensity. Physical activity was evaluated via questionnaires and accelerometer, whereas pain catastrophizing was evaluated via a questionnaire.

RESULTS

Both males and females exhibited CPM, without sex differences in the magnitude of CPM. The males showed higher resting blood pressure, higher physical activity levels, and lower pain catastrophizing scores than the females, without sex differences observed in cold pain ratings and proportion of those who met the physical activity guidelines. No correlations were observed between CPM and its determinants.

CONCLUSIONS

The results suggest the complexity of mechanisms underlying the sex differences in CPM. The sex differences in CPM, along with its determinants, may need to be examined in individuals with some risk factors for chronic pain.

COVID-Related Distress Is Associated with Increased Menstrual Pain and Symptoms in Adult Women

The COVID-19 pandemic resulted in heightened stress for many individuals, with women reporting more stress than men. Although a large body of evidence has demonstrated that stress, in general, can impact the menstrual cycle, it is not yet clear if COVID-specific stress would impact women's menstrual health. The current study explored the relationship between COVID-related stress and distress and menstrual variables (menstrual pain, number and severity of menstrual symptoms, and menstrual pain interference) in a sample of reproductive-age adult women. Seven-hundred fifteen women completed the initial survey and were re-contacted to complete the same survey three months later. Of those recontacted, 223 completed the follow-up survey. Results indicated that COVID-related stress and distress was associated with higher levels of menstrual pain, more frequent and more severe menstrual symptoms, and greater menstrual pain interference, even after accounting for age, hormonal use, bodily pain, and pain catastrophizing. Our findings suggest that women experience unique vulnerabilities that directly impact their health and functioning, and both research and clinical care should address these symptoms through careful assessment and treatment of menstrual pain and symptoms, particularly during and after periods of high stress and distress.

Association of sociodemographic factors with the prescription pattern of opioids for dental patients: a systematic review

Aim To evaluate the association of patients' sociodemographic factors (sex, age, ethnicity, income, educational level, living environment and health insurance) with the prescription pattern of opioids provided by oral health practitioners.Methods Observational studies that evaluated the association of patients' sociodemographic factors and the likelihood of receiving an opioid prescription provided by an oral health practitioner were eligible. Electronic searches were conducted in Medline (PubMed), Embase, Scopus, Web of Science, LILACS, SciELO, Google Scholar, and OpenGrey up to March 2021. Two authors independently screened the studies, performed data extraction, and assessed the risk-of-bias using the critical appraisal tools developed by the Joanna Briggs Institute (JBI). Certainty of the evidence was assessed with the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE).Results Eight studies were included in this systematic review. Publication year ranged from 2011 to 2021. Narrative synthesis showed with very low certainty of evidence that younger individuals were more likely to receive a prescription of opioids than older individuals. Regarding the other sociodemographic factors and the prescriptions of opioids in dentistry, the evidence is controversial. Risk of bias was low for most items assessed in the included studies.Conclusion The available evidence suggests that there is an association between patients' sociodemographic factors and the prescription patterns of opioids provided by oral health practitioners.

Beyond Black vs White: racial/ethnic disparities in chronic pain including Hispanic, Asian, Native American, and multiracial US adults

ABSTRACT

Previous literature on race/ethnicity and pain has rarely included all major US racial groups or examined the sensitivity of findings to different pain operationalizations. Using data from the 2010 to 2018 National Health Interview Surveys on adults 18 years or older (N = 273,972), we calculated the weighted prevalence of 6 definitions of pain to provide a detailed description of chronic pain in White, Black, Hispanic, Asian, Native American, and multiracial groups. We also estimated modified Poisson models to obtain relative disparities, net of demographic and socioeconomic (SES) factors including educational attainment, family income, and home ownership; finally, we calculated average predicted probabilities to show prevalence disparities in absolute terms. We found that Asian Americans showed the lowest pain prevalence across all pain definitions and model specifications. By contrast, Native American and multiracial adults had the highest pain prevalence. This excess pain was due to the lower SES among Native Americans but remained significant and unexplained among multiracial adults. The pain prevalence in White, Black, and Hispanic adults fell in between the 2 extremes. In this trio, Hispanics showed the lowest prevalence, an advantage not attributable to immigrant status or SES. Although most previous research focuses on Black-White comparisons, these 2 groups differ relatively little. Blacks report lower prevalence of less severe pain definitions than Whites but slightly higher prevalence of severe pain. Net of SES, however, Blacks experienced significantly lower pain across all definitions. Overall, racial disparities are larger than previously recognized once all major racial groups are included, and these disparities are largely consistent across different operationalizations of pain.

Pain catastrophizing, pain sensitivity and fear of pain are associated with early life environmental unpredictability: a path model approach

Background

Socioeconomic disadvantages in the childhood environment might strongly influence beliefs and behavior characterizing the adult years. When children experience unpredictable and adverse situations, they develop an unpredictability schema with the core belief that situations are unpredictable.

Methods

In two studies, we examined the association of childhood socioeconomic disadvantages with self-reported pain sensitivity, pain catastrophizing, and pain-related fear. Multidimensional survey measures were used to assess environmental conditions experienced in childhood. In addition, participants completed the Pain Catastrophizing Scale, Pain Sensitivity Questionnaire, Body Awareness Questionnaire, Unpredictability Schema Questionnaire, and Fear of Pain Questionnaire. In Study 1 (N = 252), in separate models, we examined pain sensitivity and pain catastrophizing of a community sample of pain-free young individuals in association with their childhood experiences. In Study 2 (N = 293), in a new sample, but with a wider age range, we examined the association of early life socioeconomic disadvantages with pain-related fear. In both studies, the predictions were tested with Structural Equation Modeling. Our models constituted a path from childhood socioeconomic status and household unpredictability to pain variables via the factors of family resources, unpredictability schemas, and body awareness.

Results and conclusions

The findings converged on the conclusion that individuals experiencing disadvantageous early life conditions tended to have an elevated level of pain catastrophizing, higher perceived sensitivity to pain, and higher level of pain-related fear. These associations were mediated by an unpredictability schema and body awareness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40359-022-00800-0.

Associations between pain catastrophizing and resting-state functional brain connectivity: Ethnic/race group differences in persons with chronic knee pain

Chronic pain is a significant public health problem, and the prevalence and societal impact continues to worsen annually. Multiple cognitive and emotional factors are known to modulate pain, including pain catastrophizing, which contributes to pain facilitation and is associated with altered resting-state functional connectivity in pain-related cortical and subcortical circuitry. Pain and catastrophizing levels are reported to be higher in non-Hispanic black (NHB) compared with non-Hispanic White (NHW) individuals. The current study, a substudy of a larger ongoing observational cohort investigation, investigated the pathways by which ethnicity/race influences the relationship between pain catastrophizing, clinical pain, and resting-state functional connectivity between anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (dlPFC), insula, and primary somatosensory cortex (S1). Participants included 136 (66 NHBs and 70 NHWs) community-dwelling adults with knee osteoarthritis. Participants completed the Coping Strategies Questionnaire-Revised Pain Catastrophizing subscale and Western Ontario and McMaster Universities Osteoarthritis Index. Magnetic resonance imaging data were obtained, and resting-state functional connectivity was analyzed. Relative to NHW, the NHB participants were younger, reported lower income, were less likely to be married, and self-reported greater clinical pain and pain catastrophizing (ps < 0.05). Ethnicity/race moderated the mediation effects of catastrophizing on the relationship between clinical pain and resting-state functional connectivity between the ACC, dlPFC, insula, and S1. These results indicate the NHB and NHW groups demonstrated different relationships between pain, catastrophizing, and functional connectivity. These results provide evidence for a potentially important role of ethnicity/race in the interrelationships among pain, catastrophizing, and resting-state functional connectivity.

Quantitative Sensory Testing Across Chronic Pain Conditions and Use in Special Populations

Chronic pain imposes a significant burden to the healthcare system and adversely affects patients' quality of life. Traditional subjective assessments, however, do not adequately capture the complex phenomenon of pain, which is influenced by a multitude of factors including environmental, developmental, genetic, and psychological. Quantitative sensory testing (QST), established as a protocol to examine thermal and mechanical sensory function, offers insight on potential mechanisms contributing to an individual's experience of pain, by assessing their perceived response to standardized delivery of stimuli. Although the use of QST as a research methodology has been described in the literature in reference to specific pain populations, this manuscript details application of QST across a variety of chronic pain conditions. Specific conditions include lower extremity chronic pain, knee osteoarthritis, chronic low back pain, temporomandibular joint disorder, and irritable bowel syndrome. Furthermore, we describe the use of QST in placebo/nocebo research, and discuss the use of QST in vulnerable populations such as those with dementia. We illustrate how the evaluation of peripheral sensory nerve function holds clinical promise in targeting interventions, and how using QST can enhance patient education regarding prognostic outcomes with particular treatments. Incorporation of QST methodology in research investigations may facilitate the identification of common mechanisms underlying chronic pain conditions, guide the development of non-pharmacological behavioral interventions to reduce pain and pain-related morbidity, and enhance our efforts toward reducing the burden of chronic pain.

Estrogen-dependent regulation of transient receptor potential vanilloid 1 (TRPV1) and P2X purinoceptor 3 (P2X3): Implication in burning mouth syndrome

Sex differences in the nervous system have gained recent academic interest. While the prominent differences are observed in mood and anxiety disorders, growing number of evidences also suggest sex difference in pain perception. This review focuses on estrogen as the key molecule underlying such difference, because estrogen plays many functions in the nervous system, including modulation of transient receptor potential vanilloid 1 (TRPV1) and P2X purinoceptor 3 (P2X3), two important nociceptive receptors. Estrogen was shown in various studies to up-regulate TRPV1 expression through two distinct pathways, resulting in pro-nociceptive effect. However, estrogen alleviated pain in other studies, by down-regulating nerve growth factor (NGF)-activated pathways and TRPV1. Estrogen may also attenuate nociception by inhibiting P2X3 receptors and ATP-signaling. Understanding the mechanism underlying the pro- and anti-nociceptive effect of estrogen might be crucial to understand pathophysiology of the burning mouth syndrome (BMS), a common chronic orofacial pain disorder in menopausal women. The involvement of TRPV1 is strongly suspected because of burning sensation. Reduced estrogen level of the BMS patient might have caused increased activity of P2X3 receptors. Interestingly, the increased expression of TRPV1 and P2X3 in oral mucosa of BMS patients was reported. The combinational impact of differential modulation of TRPV1/P2X3 during menopause might be an important contributing factor of etiology of BMS. Understanding the estrogen-dependent regulation of nociceptive receptors may provide a valuable insight toward the peripheral mechanism of sex-difference in pain perception.

The effect of photodynamic therapy on postoperative pain in teeth with primary endodontic infection

INTRODUCTION

The objective of this study was to investigate the action of photodynamic therapy on pain control after endodontic treatment in asymptomatic teeth with a primary infection, within a single visit.

METHODS

Sixty (60) single-rooted teeth with pulp necrosis and periapical lesions were selected and randomly divided into two (2) groups (n=30), according to the protocol; a control group (CG) and a group using photodynamic therapy (aPDT). The canals were instrumented with Reciproc files # 25 up to 40 along the entire length of the canal, using 2% chlorhexidine gel as the auxiliary chemical substance, followed by irrigation with sterile saline. The canals were filled with Endomethasone N cement, 0.005% methylene blue, using AsGaAl diode laser, 660 nm wavelength, 100 mW of power and 9 J of energy, using optical fibers with 365 µm in diameter.

RESULTS

Pain intensity was assessed at 8, 12, 24, 48, 72 hours and 1 week after endodontic treatment using a visual analogue scale. The level of pain was classified as none (0), mild (1-3), moderate (4-7) or severe (8-10). The data were at a significance level of 5%. There was a statistically significant difference (p<0.05) in the periods of 8, 12, 24, 48 and 72 hours between the control group and the aPDT group. After 1 week, there was no statistically significant difference.

CONCLUSIONS

It is concluded that photodynamic therapy had a significant effect on decreasing post-endodontic treatment pain in teeth with necrotic pulp and asymptomatic periapical lesions.

Race-Related Differences Between and Within Sex to Experimental Thermal Pain in Middle and Older Adulthood: An Exploratory Pilot Analysis

This brief report details a pilot analysis conducted to explore racial differences in pain sensitivity and unpleasantness between cognitively healthy Black and White adults, stratified by sex. A total of 24 cognitively healthy adults (12 Black and 12 White) from two completed studies were matched by age and sex, and divided into two groups based on race. Stratified analyses by sex demonstrated that Black females reported experiencing pain intensity ratings of all three intensity sensations at lower temperatures than White females. These findings will inform future research studies to determine if these results hold true in a fully-powered sample and should include mixed methodologies, incorporating neuroimaging data to further assess this phenomenon. Improving pain assessment and management across racial/ethnic groups will help healthcare providers such as nurses and physicians to ensure optimal quality of life for all.

Unsupervised Machine Learning Identified Distinct Population Clusters Based on Symptoms of Oral Pain, Psychological Distress, and Sleep Problems

Objectives:

The aims of this study were to explore the use of unsupervised machine learning in clustering the population based on reports of oral pain, psychological distress, and sleep problems and to compare demographic and socio-economic characteristics as well as levels of functional domains (work, social, and leisure) between clusters.

Materials and Methods:

In this cross-sectional study, a total of 1613 participants from the National Health and Nutrition Examination Survey in 2017–2018 were analyzed. Five variables, including oral pain, depression, anxiety, sleep apnea, and excessive daytime sleepiness, were selected for cluster analysis using the k-medoids clustering algorithm. The distribution of categorical variables between clusters was assessed using χ² test. One-way analysis of variance and Kruskal–Wallis H test were used to compare numerical variables as appropriate.

Results:

Five distinct clusters were identified: healthy, norm, anxiety, apnea-comorbid, and pain-comorbid. The apnea-comorbid cluster had mean age of 59 years and higher proportion of men. The pain-comorbid cluster had mean age of 56 years and higher proportion of women. Whites constituted a majority of both comorbid clusters. The pain-comorbid cluster demonstrated the least percentage of individuals with college degree, the lowest income, and significant impairment in all functional domains.

Conclusion:

Through the use of unsupervised machine learning, the clusters with comorbidity of oral pain, psychological distress, and sleep problems have emerged. Major characteristics of the comorbid clusters included mean age below 60 years, White, and low levels of education and income. Functional domains were significantly impaired. The comorbid clusters thus call for public health intervention.

Predictors of persistent postoperative pain after surgery for idiopathic scoliosis

PURPOSE

To identify factors contributing to persistent postoperative pain in patients treated surgically for idiopathic scoliosis.

METHODS

In total, 280 patients aged ten through 25 years at surgery, were identified in the Swedish Spine registry; all having preoperative and postoperative visual analogue scale (VAS) for back pain scores. The patients were divided into a high and low postoperative pain group based on the reported postoperative VAS for back pain scores (by using 45 mm on the 0 mm to 100 mm VAS scale as a cut-off). The patient-reported questionnaire included VAS for back pain, the 3-level version of EuroQol 5-dimensional (EQ-5D-3L) instrument, the EuroQol VAS (EQ-VAS) and the Scoliosis Research Society 22r instrument (SRS-22r). Predictors of postoperative back pain were searched in the preoperative data.

RESULTS

The 67 (24%) patients that reported high postoperative VAS back pain (> 45 mm) also reported lower postoperative EQ-5D-3L, EQ-VAS and SRS-22r than patients with low postoperative VAS back pain (all p < 0.001). Two preoperative variables were independently associated with postoperative pain; each millimetre increase in preoperative VAS back pain (on the 0 mm to 100 mm scale) was associated with a higher risk of being in the high postoperative back pain group (odds ratio (OR) 1.03; 95% confidence interval (CI) 1.02 to 1.05) and each 1 point decrease on the preoperative SRS-22r mental health (scale from 1 to 5) was associated with a higher risk of being in the high postoperative back pain group (OR 1.68; 95% CI 1.03 to 2.73).

CONCLUSION

High preoperative back pain and low preoperative mental health are independent predictors of back pain after surgery for idiopathic scoliosis.

LEVEL OF EVIDENCE

III.

The role of self-evaluated pain sensitivity as a mediator of objectively measured pain tolerance in Native Americans: findings from the Oklahoma Study of Native American Pain Risk (OK-SNAP)

Native Americans (NAs) are at increased risk for chronic pain. One mechanism contributing to this pain disparity could be personal pain beliefs, which may influence actual pain sensitivity. Thus, we examined whether self-evaluated pain sensitivity (SEPS) mediates the relationship between ethnicity [NAs vs. non-Hispanic Whites (NHWs)] and objectively-measured pain tolerance, and whether catastrophic thinking and pain-related anxiety influence these pain beliefs. 232 healthy, pain-free NAs and NHWs completed questionnaires measuring SEPS, catastrophizing, and anxiety. Objective pain tolerance was also assessed. Results suggested: (1) NAs reported higher levels of SEPS, catastrophizing, and anxiety, (2) catastrophizing may have enhanced anxiety and both catastrophizing and anxiety were associated with higher SEPS, and (3) anxiety and SEPS were associated with lower pain tolerance. A significant bootstrapped mediation analysis suggested NAs experienced higher pain-related anxiety, which may have promoted higher SEPS, that in turn reduced pain tolerance. Longitudinal research is needed to confirm this.

Association of temporomandibular disorders with pain sensitivity: A cohort study

BACKGROUND

Pain related to temporomandibular disorders (TMD) can be linked with multiple site pain (MSP), and may associate with increased pain sensitivity, more frequently among women than men. The aim of the study was to examine the associations of pressure pain threshold (PPT) and tolerance (PPTo) with TMD and associated MSP in the Northern Finland Birth Cohort 1966 (NFBC1966) study.

METHODS

Altogether 1961 NFBC1966 subjects attended clinical medical and dental examination at the Institute of Dentistry, University of Oulu in 2012-2013. Clinical examinations were carried out using a modified Diagnostic Criteria for TMD protocol (DC/TMD). MSP was defined based on questions regarding body pain sites. Additionally, PPT and PPTo were assessed using algometer measurements. Mann-Whitney U-test and Tobit regression models were used to analyse associations between TMD sub-diagnoses, MSP, PPT and PPTo, stratified by sex. Further models were adjusted with anxiety and depressive symptoms, which were assessed using Hopkins Symptom Checklist-25 (HSCL-25) and two-way interaction terms.

RESULTS

Among females, lower PPT and PPTo were associated with myalgia and arthralgia. Among males, lower PPT and PPTo were associated with MSP-linked TMD. Tobit regression analysis showed significantly lower PPT and PPTo values in the myalgia and arthralgia subgroups among female TMD subjects. Among females, disc displacement with reduction had an inverse association with PPT and PPTo. Among males, lower PPTo was associated with degenerative joint disease and MSP-linked TMD.

CONCLUSIONS

The pain regulatory mechanisms behind TMD act differently between the genders as local TMD among females and MSP-linked TMD among males were associated with pain sensitivity.

SIGNIFICANCE

The study shows that there are differences in the associations of painful TMD with pressure pain tolerance, pressure pain sensitivity and MSP between male and female subjects.

Sleep and neighborhood socioeconomic status: a micro longitudinal study of chronic low-back pain and pain-free individuals

Individuals with chronic low back pain (cLBP) frequently report sleep disturbances. Living in a neighborhood characterized by low-socioeconomic status (SES) is associated with a variety of negative health outcomes, including poor sleep. Whether low-neighborhood SES exacerbates sleep disturbances of people with cLBP, relative to pain-free individuals, has not previously been observed. This study compared associations between neighborhood-level SES, pain-status (cLBP vs. pain-free), and daily sleep metrics in 117 adults (cLBP = 82, pain-free = 35). Neighborhood-level SES was gathered from Neighborhood Atlas, which provides a composite measurement of overall neighborhood deprivation (e.g. area deprivation index). Individuals completed home sleep monitoring for 7-consecutive days/nights. Neighborhood SES and pain-status were tested as predictors of actigraphic sleep variables (e.g., sleep efficiency). Analyses revealed neighborhood-level SES and neighborhood-level SES*pain-status interaction significantly impacted objective sleep quality. These findings provide initial support for the negative impact of low neighborhood-level SES and chronic pain on sleep quality.

Pain, symptom distress, and pain barriers by age among patients with cancer receiving hospice care: Comparison of baseline data

OBJECTIVES

Age group differences have been reported for pain and symptom presentations in outpatient and inpatient oncology settings, but it is unknown if these differences occur in hospice. We examined whether there were differences in pain, symptom distress, pain barriers, and comorbidities among three age groups (20-64 years, 65-84 years, and 85+) of hospice patients with cancer.

MATERIALS AND METHODS

Participants were recruited from two hospices. Half were women; 49% White and 34% Black. 42% were 20-64 y, 43% 65-84 y, and 15% 85+ y. We analyzed baseline data for 230 hospice patients with cancer (enrolled 2014-2016, mean age 68.2 ± 14.0, 20-100 years) from a stepped-wedge randomized controlled trial. Measures were the Average pain intensity (API, 0-10: current, least and worst pain intensity during the past 24 h), Symptom Distress Scale (SDS, 13-65), Barriers Questionnaire-13 (BQ-13, 0-5), and comorbid conditions. Descriptive, bivariate association, and multiple regression analyses were performed.

RESULTS

Mean API scores differed (p < .001) among the three age groups (5.6 ± 2.0 [20-64 years], 4.7 ± 2.0 [65-84 years], and 4.4 ± 1.8 [85+], as did the mean SDS scores (36.1 ± 7.3, 33.5 ± 8.1, and 31.6 ± 6.6, p = .004). BQ-13 mean scores (2.6 ± 0.9, 2.7 ± 0.8, and 2.5 ± 0.7) and comorbidities were not significantly different across age groups. In multiple regression analyses, age-related differences in API and SDS remained significant after adjusting for gender, race, cancer, palliative performance score, and comorbidities. Comorbidities were positively associated with SDS (p = .046) but not with API (p = .64) in the regression model.

CONCLUSION

Older hospice patients with cancer reported less pain and symptoms than younger patients, but all groups reported similar barriers to pain management. These findings suggest the need for age- and race-sensitive interventions to reduce pain and symptom distress levels at life's end.

Treatment responses in chronic temporomandibular patients depending on the treatment modalities and frequency of parafunctional behaviour

OBJECTIVES

(i) To evaluate the effect of three different interventions on treatment outcomes and (ii) to determine how the frequency of oral parafunction influences the effectiveness of the different therapeutic modalities.

METHODS

Forty-five participants were randomly assigned into three treatment groups [physical therapy (PT), stabilisation splint (SS) and control therapy (CT)]. According to Oral Behavior Checklist score, participants were divided into "high-frequency parafunction" (HFP) and low-frequency parafunction" (LFP) group. Primary (spontaneous pain and characteristic pain intensity) and secondary outcomes (range of mouth opening, anxiety symptoms, quality of life, perceived stress and global functional limitation) were evaluated during six-month treatment period.

RESULTS

Participants in PT group showed a significant reduction in characteristic pain intensity (p = .047, η²  = 0.243) when compared to SS and CT group, but significant improvement in spontaneous pain was found in all treatment groups. Patients treated with PT and SS exhibited significantly stronger improvement in pain-free mouth opening than patients in CT group (3rd month: p=.037, η2=0.258; 6th month: p = .005, η²  = 0.383). Within-group analyses showed significant decrease of perceived stress, anxiety symptoms and global functional limitation only in PT group over a six-month treatment period. Participants with HFP presented significantly greater levels of anxiety (3rd month: p = .009, η²  = 0.275; 6th month: p = .041, η²  = 0.176) than participants with LFP. Within-group analyses, however, showed significant improvement of anxiety, but also the decrease of perceived stress and improvement of global limitation for the HFP group but not for the LFP group.

CONCLUSION

Although no treatment can be marked as superior in terms of spontaneous pain relief, PT was more effective when observing relief of characteristic pain intensity. In HFP group the reduction of anxiety, stress and functional limitation was present regardless of the applied therapy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04694274. Registered on 01/04/2021.

Differences in Psychosocial Factors and Experimental Pain Sensitivity between Hispanics and non-Hispanic Whites from the U.S.-Mexico Border

PURPOSE

Research suggests that ethnicity is a predictor of pain-related outcomes; however, studies comparing the differences in experimental pain sensitivity between Hispanics and non-Hispanic Whites (NHW) are scarce. This study investigated these differences between Hispanics and NHW from the U.S- Mexico border.

METHODS

Fifty-eight healthy subjects completed the survey packet, which included a demographic and a psychosocial factors questionnaire. Participants underwent quantitative sensory testing which included heat pain threshold, heat pain tolerance, Suprathreshold Heat Pain Response (SHPR), and Conditioned Pain Modulation (CPM). SHPR was induced by repeated thermal stimuli in both thenar eminences. CPM was assessed using SHPR as the experimental stimulus, and cold pressor task as the conditioning stimulus.

RESULTS

Analyses showed significant differences in experimental pain measures believed to be representative of facilitatory pain processing including SHPR, and heat pain threshold, where Hispanics reported significantly higher pain ratings than NHW. Hispanics also reported higher levels of ethnic identity and acculturation. However, these factors were not significantly associated with experimental pain sensitivity.

CONCLUSION

The experimental pain sensitivity and psychosocial factors included in this study differed by ethnic group, where Hispanics reported significantly higher pain ratings, when compared to NHW. However, ethnic identity and acculturation were not associated with these pain-related outcomes. Overall, enhanced understanding by clinicians of pain sensitivity and disparities in the pain experience between ethnic groups allows for increased cultural sensitivity and can be used to optimize pain treatment on an individual-by-individual basis.

Pain Prevalence, Chronicity and Impact Within Subpopulations Based on Both Hispanic Ancestry and Race: United States, 2010-2017

We provide national surveillance estimates of pain chronicity, severity and impact in adult subpopulations defined by both Hispanic Ancestry and Race. Data are from 144,434 adults who completed validated questionnaires in the 2010-2017 National Health Interview Survey asking about pain status within the last 3 (N = 84,664) or 6 months (N = 59,770). Multivariable logistic regression was used to assess the relationship between pain and ethnicity/race. Compared to White Puerto Rican participants, White participants with Central/South American and Mexican ancestry had reduced odds of reporting Category 3-4 pain and High-Impact Chronic Pain (HICP), while those of Cuban ancestry had reduced odds of only HICP - eg, White participants with Mexican ancestry had 32% lower odds of having Category 3-4 pain and 50% lower odds of having HICP. While no differences were seen between White Puerto Rican and White Non-Hispanic participants for Category 3-4 pain, White Non-Hispanics had 40% lower odds of reporting HICP. Asian Non-Hispanic and Black Non-Hispanic participants had significantly lower odds of reporting Category 3-4 pain and HICP compared to White Puerto Rican participants, eg, Black Non-Hispanic participants had 26% lower odds off having Category 3-4 pain and 42% lower odds of having HICP. Perspective: By examining pain status in discrete demographic groups based on Hispanic Ancestry and Race, this report further documents substantial difference in health status among underserved populations and provides a baseline for continuing surveillance research on pain, with the eventual goal of eliminating disparities in pain assessment and treatment.

Interaction Between Sex and Cardiac Interoceptive Accuracy in Measures of Induced Pain

Pain perception is influenced by several factors, and among them, affect, sex, and perception of bodily signals are assumed to play a prominent role. The aim of the present study is to explore how sex, cardiac interoceptive accuracy, and the interaction of the latter two influence the perception of experimentally induced pain. We investigated a large sample of young adults (n = 159, 50.9% female, age: 23.45, SD = 3.767), assessing current positive and negative affective state with the Positive and Negative Affect Schedule (both involved as control variables), cardiac interoceptive accuracy with the mental heartbeat tracking task, and pain sensitivity with electrical stimulation on the back of the dominant hand, applying a repeated-measures staircase protocol. Males showed a significantly higher pain threshold and tolerance level than females, whereas cardiac interoceptive accuracy was not associated with pain sensitivity. The impact of sex × cardiac interoceptive accuracy interaction was significant for pain threshold only, while pain tolerance was predicted only by sex. According to these findings, the associations between pain sensitivity, cardiac IAc, and sex might be more complicated than it was supposed in previous studies. Interactions between factors impacting pain perception appear worthy of further investigation.

Effects of sex on placebo effects in chronic pain participants: a cross-sectional study

ABSTRACT

Sex-related differences can influence outcomes of randomized clinical trials and may jeopardize the effectiveness of pain management and other therapeutics. Thus, it is essential to understand the mechanistic and translational aspects of sex differences in placebo outcomes. Recently, studies in healthy participants have shed light on how sex-related placebo effects might influence outcomes, yet no research has been conducted in a patient population. Herein, we used a tripartite approach to evaluate the interaction of prior therapeutic experience (eg, conditioning), expectations, and placebo effects in 280 chronic (orofacial) pain patients (215 women). In this cross-sectional study, we assessed sex differences in placebo effects, conditioning as a proxy of prior therapeutic effects, and expectations evaluated before and after the exposure to positive outcomes, taking into account participant-experimenter sex concordance and hormonal levels (estradiol and progesterone assessed in premenopausal women). We used mediation analysis to determine how conditioning strength and expectations impacted sex differences in placebo outcomes. Independent of gonadal hormone levels, women showed stronger placebo effects than men. We also found significant statistical sex differences in the conditioning strength and reinforced expectations whereby reinforced expectations mediated the sex-related placebo effects. In addition, the participant-experimenter sex concordance influenced conditioning strength, reinforced expectations, and placebo effects in women but not in men. Our findings suggest that women experience larger conditioning effects, expectations, and placebo effects emphasizing the need to consider sex as a biological variable when placebo components of any outcomes are part of drug development trials and in pain management.

Advanced age attenuates the antihyperalgesic effect of morphine and decreases μ-opioid receptor expression and binding in the rat midbrain periaqueductal gray in male and female rats

The present study investigated the impact of advanced age on morphine modulation of persistent inflammatory pain in male and female rats. The impact of age, sex, and pain on μ-opioid receptor (MOR) expression and binding in the ventrolateral periaqueductal gray (vlPAG) was also examined using immunohistochemistry and receptor autoradiography. Intraplantar administration of complete Freund's adjuvant induced comparable levels of edema and hyperalgesia in adult (2-3 mos) and aged (16-18 mos) male and female rats. Morphine potency was highest in adult males, with a greater than two-fold increase in morphine EC50 observed in adult versus aged males (3.83 mg/kg vs. 10.16 mg/kg). Adult and aged female rats also exhibited significantly higher EC50 values (7.76 mg/kg and 8.74 mg/kg, respectively) than adult males. The upward shift in EC50 from adult to aged males was paralleled by a reduction in vlPAG MOR expression and binding. The observed age-related reductions in morphine potency and vlPAG MOR expression and binding have significant implications in pain management in the aged population.

Within-session test-retest reliability of pressure pain threshold and mechanical temporal summation in healthy subjects

Objective

To determine the absolute and relative intra-rater within-session test-retest reliability of pressure pain threshold (PPT) and mechanical temporal summation of pain (TSP) at the low back and the forearm in healthy participants and to test the influence of the number and sequence of measurements on reliability metrics.

Methods

In 24 participants, three PPT and TSP measures were assessed at four sites (2 at the low back, 2 at the forearm) in two blocks of measurements separated by 20 minutes. The standard error of measurement, the minimal detectable change (MDC) and the intraclass correlation coefficient (ICC) were investigated for five different sequences of measurements (e.g. measurement 1, 1–2, 1-2-3).

Results

The MDC for the group (MDC_gr) for PPT ranged from 28.71 to 50.56 kPa across the sites tested, whereas MDC_gr for TSP varied from 0.33 to 0.57 out of 10 (numeric scale). Almost all ICC showed an excellent relative reliability (between 0.80 and 0.97), except when only the first measurement was considered (moderate). Although minimal differences in absolute PPT reliability were present between the different sequences, in general, using only the first measurement increase measurement error. Three TSP measures reduced the measurement error.

Discussion

We established that two measurements of PPT and three of TSP reduced the measurement error and demonstrated an excellent relative reliability. Our results could be used in future pain research to confirm the presence of true hypo/hyperalgesia for paradigms such as conditioned pain modulation or exercise-induced hypoalgesia, indicated by a change exceeding the measurement variability.

Effect of 940 nm laser diode irradiation prior to bonding procedure on postoperative sensitivity following class II composite restorations: a split-mouth randomized clinical trial

The aim of this study was to evaluate the effect of 940 nm laser diode on class II composite cavities prior to bonding and restoration process on the postoperative sensitivity (POS). Thirty patients with two bilateral premolars with mesio or disto-occlusal carious lesions were evaluated. In each patient, the teeth were randomly divided into the control and laser groups. After cavity preparation and isolation and before the bonding process, the laser group was subjected to 940 nm irradiation (Epic 10, Biolase, USA) by 400 μ tip continuously at 100 mW with 398 J/cm² energy density of tip, which was applied for 5 s at a distance of 2 mm on the axial wall of the cavity. In the control group, irradiation was performed by using the aiming beam. Access cavity was then restored with a composite resin. Cold sensitivity was measured using a cold spray application on the middle third of teeth buccal surface at baseline (before the intervention), 1, 14, and 30 days after the restoration by visual analog scale (VAS) criteria. The mean Friedman and Wilcoxon signed-rank tests were used for data analysis. It was shown that in both laser and control groups, the VAS was significantly decreased at all times compared to the baseline (p ≤ 0.05). There was no statistically significant difference between the mean VAS of two groups at baseline and first day (p ≤ 0.05), but at 14 and 30 days after the intervention, it was significantly lower in the laser group (p ≤ 0.05). The results of this study demonstrated that the cavity pretreatment with laser diode (940 nm) effectively reduces the postoperative sensitivity in class II composite restorations.

Self-reported sensory responsiveness patterns in typically-developing and early-onset schizophrenia adolescents: Its relationship with schizotypal and autistic traits

Altered behavioural responses to sensory stimuli, including both hypo- and hyper-reactivity, have been found in individuals with schizophrenia. However, how specific sensory responsiveness patterns are associated with symptomatology of schizophrenia remains largely unknown. The present study aimed to examine sensory responsiveness in typically-developing (TD) adolescents (n = 98) and adolescents with early-onset schizophrenia (EOS) (n = 29) and investigate the relationship between schizotypal traits and sensory responsiveness patterns. All participants completed the Adult/Adolescent Sensory Profile (AASP), the Schizotypal Personality Questionnaire (SPQ) and the Autism Spectrum Quotient (AQ). Results showed that higher levels of hypersensitivity and hyposensitivity coexisted in EOS patients and were correlated with positive and negative symptoms of schizophrenia. Atypical sensory experiences except for sensory seeking were found to be positively correlated with higher levels of schizotypal traits regardless of diagnostic status. Moreover, the strength and pattern of such correlations were comparable in both EOS and TD groups. This study also provided evidence that higher levels of autistic traits would intensify the positive correlation between schizotypal traits and sensory responsiveness abnormalities, suggesting an additive effect of co-occurring schizotypal and autistic traits on atypical sensory experiences. These findings extend previous research by depicting sensory responsiveness patterns in younger populations with schizophrenia, and may have implications for future development of sensory-related interventions in clinical settings.

Effects of Language Context and Cultural Identity on the Pain Experience of Spanish-English Bilinguals

While language and culture influence cognition, their role in shaping pain remains understudied. We tested whether language and cultural identification influence pain report among Spanish-English bilinguals. Eighty bilingual Hispanics/Latinos (40 female) experienced painful thermal stimulations, providing pain intensity and unpleasantness ratings, on separate English and Spanish testing days. Participants' skin conductance responses (SCRs) during stimulations served as measures of physiological arousal. Bilingual participants showed larger SCRs and higher pain intensity when speaking the language congruent with their dominant cultural identification. That is, those endorsing more Hispanic cultural identification showed higher pain in Spanish, while US-American-dominant participants demonstrated increased pain in English. Follow-up moderated mediation demonstrated that SCRs mediated language effects on pain ratings for participants endorsing greater Hispanic cultural identification. Together, our results suggest language, cultural associations, and bodily arousal synergistically influence pain evaluations among bilingual people, potentially contributing to well-documented health disparities between Hispanic and non-Hispanic communities.