Sex and Race Differences in Pain Sensitization among Patients with Chronic Low Back Pain

Associations between pain intensity, pain sensitivity, demographics, psychological factors, disability, physical activity, pain phenotype and COVID-19 history in low back pain: An observational study

BACKGROUND AND PURPOSE

Knowledge of the factors affecting pain intensity and pain sensitivity can inform treatment targets and strategies aimed at personalizing the intervention, conceivably increasing its positive impact on patients. Therefore, this study aimed to investigate the association between demographic factors (sex and age), body mass index (BMI), psychological factors (anxiety and depression, kinesiophobia and catastrophizing), self-reported physical activity, pain phenotype (symptoms of central sensitization, and nociceptive or neuropathic pain), history of COVID-19 and pain intensity and sensitivity in patients with chronic non-specific low back pain (LBP).

METHODS

This was a cross-sectional secondary analysis with 83 participants with chronic non-specific LBP recruited from the community between August 2021 and April 2022. BMI, pain intensity (Visual Analog Scale), pain sensitivity at the lower back and at a distant point [pressure pain threshold], catastrophizing (Pain Catastrophizing Scale), kinesiophobia (Tampa Scale for Kinesiophobia), anxiety and depression (Hospital Anxiety and Depression Scale), pain phenotype (Central Sensitization Inventory and PainDetect Questionnaire), physical activity (International Physical Activity Questionnaire), and disability (Roland Morris Disability Questionnaire) were assessed. Multiple linear regression analyses with pain intensity and sensitivity as the dependent variables were used.

RESULTS

The model for pain intensity explained 34% of its variance (Adjusted R2 = -0.343, p < 0.001), with depression and anxiety (p = 0.008) and disability (p = 0.035) reaching statistical significance. The model for pain sensitivity at the lower back, also explained 34% of its variance (Adjusted R2 = 0.344, p < 0.001) at the lower back with sex, BMI, and kinesiophobia reaching statistical significance (p < 0.05) and 15% of the variance at a distant body site (Adjusted R2 = 0.148, p = 0.018) with sex and BMI reaching statistical significance (p < 0.05).

DISCUSSION

This study found that different factors are associated with pain intensity and pain sensitivity in individuals with LBP. Increased pain intensity was associated with higher levels of anxiety and depression and disability and increased pain sensitivity was associated with being a female, higher kinesiophobia, and lower BMI.

Weak Relationships Between Psychological Factors and Experimental Pain Outcomes in Pain-Free Individuals: An Aggregate Analysis of 8 Studies

Although psychological factors such as anxiety, depression, and pain catastrophizing are known to influence pain outcomes in chronic pain populations, there are mixed results regarding whether they influence experimental pain outcomes in pain-free individuals. The objectives of this study were to determine the associations between psychological factors and experimental pain outcomes in pain-free adolescents and adults. Relationships between anxiety, depression, and pain catastrophizing and experimental pain outcomes across 8 different studies (total N = 595) were examined in different populations of pain-free adult and adolescent participants. Analyses were conducted with and without controlling for sex, age, and race. Studies were analyzed separately and as part of an aggregate analysis. Individual study analyses resulted in 136 regression models. Of these, only 8 models revealed a significant association between psychological factors and pain outcomes. The significant results were small and likely due to Type 1 error. Controlling for demographic factors had minimal effect on the results. The aggregate analyses revealed weak relationships between anxiety and pressure pain threshold (Fisher's z = -.10 [-.19, -.01]), anxiety and cold pain intensity ratings (Fisher's z = .18 [.04, .32]), and pain catastrophizing and pressure pain threshold (Fisher's z = -.14 [-.26, -.02]). Sample size calculations based on the aggregate analyses indicated that several hundred participants would be required to detect true relationships between these psychological factors and pain measures. The overall negative findings suggest that in pain-free individuals, anxiety, depression, and pain catastrophizing are not meaningfully related to experimental pain outcomes. PERSPECTIVE: Psychological variables have been shown to predict pain outcomes in chronic pain populations but these relationships may not generalize to pain-free populations. An analysis of 595 pain-free individuals across 8 studies in our lab revealed that anxiety, depression, and pain catastrophizing were not meaningfully related to experimental pain outcomes.

Associations of pain sensitivity and conditioned pain modulation with physical activity: findings from the Multicenter Osteoarthritis Study (MOST)

OBJECTIVE

Individuals with chronic pain due to knee osteoarthritis (OA) are insufficiently physically active, and alterations of facilitatory and inhibitory nociceptive signaling are common in this population. Our objective was to examine the association of these alterations in nociceptive signaling with objective accelerometer-based measures of physical activity in a large observational cohort.

DESIGN

We used data from the Multicenter Osteoarthritis Study. Measures of peripheral and central pain sensitivity included pressure pain threshold at the knee and mechanical temporal summation at the wrist, respectively. The presence of descending pain inhibition was assessed by conditioned pain modulation (CPM). Physical activity was quantitatively assessed over 7 days using a lower back-worn activity monitor. Summary metrics included steps/day, activity intensity, and sedentary time. Linear regression analyses were used to evaluate the association of pain sensitivity and the presence of descending pain inhibition with physical activity measures.

RESULTS

Data from 1873 participants was analyzed (55.9% female, age = 62.8 ± 10.0 years). People having greater peripheral and central sensitivity showed lower step counts. CPM was not significantly related to any of the physical activity measures, and none of the exposures were significantly related to sedentary time.

CONCLUSIONS

In this cohort, greater peripheral and central sensitivity were associated with reduced levels of objectively-assessed daily step counts. Further research may investigate ways to modify or treat heightened pain sensitivity as a means to increase physical activity in older adults with knee OA.

How to make calibration less painful-A proposition for an automatic, reliable and time-efficient procedure

In behavioral and neurophysiological pain studies, multiple types of calibration methods are used to quantify the individual pain sensation stimuli. Often, studies lack a detailed calibration procedure description, data linearity, and quality quantification and omit required control for sex pain differences. This hampers study repetition and interexperimental comparisons. Moreover, typical calibration procedures require a high number of stimulations, which may cause discomfort and stimuli habituation among participants. To overcome those shortcomings, we present an automatic calibration procedure with a novel stimuli estimation method for intraepidermal stimulation. We provide an in-depth data analysis of the collected self-reports from 70 healthy volunteers (37 males) and propose a method based on a dynamic truncated linear regression model (tLRM). We compare its estimates for the sensation (t) and pain (T) thresholds and mid-pain stimulation (MP), with those calculated using traditional estimation methods and standard linear regression models. Compared to the other methods, tLRM exhibits higher R2 and requires 36% fewer stimuli applications and has significantly higher t intensity and lower T and MP intensities. Regarding sex differences, t and T were found to be lower for females compared to males, regardless of the estimation method. The proposed tLRM method quantifies the calibration procedure quality, minimizes its duration and invasiveness, and provides validation of linearity between stimuli intensity and subjective scores, making it an enabling technique for further studies. Moreover, our results highlight the importance of control for sex in pain studies.

Racial Differences in Movement-Related Appraisals and Pain Behaviors Among Adults With Chronic Low Back Pain

Research documents racial disparities in chronic low back pain (CLBP). Few studies have examined racial disparities in movement-related appraisals and no studies have examined anticipatory appraisals prior to or pain behaviors during functional activities among individuals with CLBP. This cross-sectional study examined racial differences in anticipatory appraisals of pain, concerns about harm, and anxiety, appraisals of pain and anxiety during movement, and observed pain behaviors during 3 activities of daily living (supine-to-standing bed task, sitting-to-standing chair task, floor-to-waist lifting task) in a sample (N = 126) of non-Hispanic Black (31.0%), Hispanic (30.2%), and non-Hispanic White (38.9%) individuals with CLBP. Hispanic participants reported more expected pain, concerns about harm, and pre-movement anxiety prior to the bed and chair tasks compared to non-Hispanic White participants. Hispanic participants reported more pain during the bed task and more anxiety during the bed and chair tasks compared to non-Hispanic White participants. Non-Hispanic Black participants reported more expected pain, concerns about harm, and pre-movement anxiety prior to the bed task and more pre-movement anxiety prior to the chair task compared to non-Hispanic White participants. Non-Hispanic Black participants reported more anxiety during the bed and chair tasks compared to non-Hispanic White participants. Non-Hispanic Black participants were observed to have significantly more verbalizations of pain during the bed task compared to non-Hispanic White participants. Current findings identify racial disparities in important cognitive-behavioral and fear-avoidance mechanisms of pain. Results indicate a need to revisit traditional theoretical and treatment models in CLBP, ensuring racial disparities in pain cognitions are considered. PERSPECTIVE: This study examined racial disparities in anticipatory and movement-related appraisals, and pain behaviors during activities of daily living among Non-Hispanic Black, Non-Hispanic White, and Hispanic individuals with CLBP. Racial disparities identified in the current study have potentially important theoretical implications surrounding cognitive-behavioral and fear-avoidance mechanisms of pain.

Uncovering moderators of pain perception by women with endometriosis from Latin America and Spain: the roles of sociodemographics, racial self-identity, and pain catastrophizing

ABSTRACT

A cross-sectional multinational collaborative study on women with endometriosis from Latin America and Spain uncovered high levels of painful symptomatology and high pain catastrophizing scores. Associations between pain perception/catastrophizing and race/ethnicity have been documented. This study was conducted to uncover factors moderating pelvic pain severity, including socioeconomic variables, self-identified race, and pain catastrophizing in women with endometriosis from Latin America and Spain, a population encompassing diverse racial and sociocultural contexts. Self-reported data on demographics, clinical history, Ob-Gyn history, pelvic pain intensity, and pain catastrophizing were collected with the Spanish World Endometriosis Research Foundation (WERF) Endometriosis Phenome Project (EPhect) Clinical Questionnaire (ECQ). Multiple logistic regression was conducted to analyze effects of self-identified race, demographic clusters (defined as countries with similar racial population distribution), socioeconomic factors, and pain catastrophizing on reporting severe vs moderate-mild levels of dysmenorrhea, dyspareunia, and pelvic pain. Self-identified race did not affect the likelihood of reporting severe pelvic pain; however, there were significant differences in reporting severe dysmenorrhea at worst among demographic clusters. Older age was associated with severe dyspareunia at worst and recent pelvic pain. Pain catastrophizing score was highly predictive of reporting most types of severe pelvic pain, regardless of race and demographic cluster. These results negate a role of racial categories as moderator of pain in women from Latin America and Spain and support integration of pain catastrophizing assessments and psychological interventions into the pain management plan to enhance therapeutic outcomes and QoL for patients with endometriosis.

Mechanisms of pain in aging and age-related conditions: Focus on caregivers

Pain is a complex, subjective experience that can significantly impact quality of life, particularly in aging individuals, by adversely affecting physical and emotional well-being. Whereas acute pain usually serves a protective function, chronic pain is a persistent pathological condition that contributes to functional deficits, cognitive decline, and emotional disturbances in the elderly. Despite substantial progress that has been made in characterizing age-related changes in pain, complete mechanistic details of pain processing mechanisms in the aging patient remain unknown. Pain is particularly under-recognized and under-managed in the elderly, especially among patients with Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other age-related conditions. Furthermore, difficulties in assessing pain in patients with AD/ADRD and other age-related conditions may contribute to the familial caregiver burden. The purpose of this article is to discuss the mechanisms and risk factors for chronic pain development and persistence, with a particular focus on age-related changes. Our article also highlights the importance of caregivers working with aging chronic pain patients, and emphasizes the urgent need for increased legislative awareness and improved pain management in these populations to substantially alleviate caregiver burden.

Predictors of response in PROMIS-global in a chronic low back pain specialty clinic: STarTBack and chronic overlapping pain conditions

BACKGROUND

Tools, such as the STarTBack Screening Tool (SBT), have been developed to identify risks of progressing to chronic disability in low back pain (LBP) patients in the primary care population. However, less is known about predictors of change in function after treatment in the specialty care population.

OBJECTIVE

We pursued a retrospective observational cohort study involving LBP patients seen in a multidisciplinary specialty clinic to assess which features can predict change in function at follow-up.

METHODS

The SBT was administered at initial visit, and a variety of patient characteristics were available in the chart including the presence of chronic overlapping pain conditions (COPCs). Patient Reported Outcomes Measurement Information System-10 (PROMIS-10) global physical health (PH) and global mental health (MH) were measured at baseline and at pragmatic time points during follow-up. Linear regression was used to estimate adjusted associations between available features and changes in PROMIS scores.

RESULTS

241 patients were followed for a mean of 17.0 ± 7.5 months. Mean baseline pain was 6.7 (SD 2.1), PROMIS-10 global MH score was 44.8 (SD 9.3), and PH score was 39.4 (SD 8.6). 29.7% were low-risk on the SBT, 41.8% were medium-risk, and 28.5% were high-risk. Mean change in MH and PH scores from baseline to the follow-up questionnaire were 0.86 (SD 8.11) and 2.39 (SD 7.52), respectively. Compared to low-risk patients, high-risk patients had a mean 4.35 points greater improvement in their MH score (p= 0.004) and a mean 3.54 points greater improvement in PH score (p= 0.006). Fewer COPCs also predicted greater improvement in MH and PH.

CONCLUSIONS

SBT and the presence of COPC, which can be assessed at initial presentation to a specialty clinic, can predict change in PROMIS following treatment. Effort is needed to identify other factors that can help predict change in function after treatment in the specialty care setting.

Race-Based Differences in the Response to a Mindfulness Based Integrative Medical Group Visit Intervention for Chronic Pain

Background

Chronic pain is one of the most common drivers of healthcare utilization and a marked domain for health disparities, as African American/Black populations experience high rates of chronic pain. Integrative Medical Group Visits (IMGV) combine mindfulness techniques, evidence-based integrative medicine, and medical group visits. In a parent randomized controlled trial, this approach was tested as an adjunct treatment in a diverse, medically underserved population with chronic pain and depression.

Objective

To determine race-based heterogeneity in the effects of a mindfulness based treatment for chronic pain.

Methods

This secondary analysis of the parent trial assessed heterogeneity of treatment effects along racialized identity in terms of primary patient-reported pain outcomes in a racially diverse sample suffering from chronic pain and depression. The analytic approach examined comorbidities and sociodemographics between racialized groups. RMANOVAs examined trajectories in pain outcomes (average pain, pain severity, and pain interference) over three timepoints (baseline, 9, and 21 weeks) between participants identifying as African American/Black (n = 90) vs White (n = 29) across both intervention and control conditions.

Results

At baseline, African American/Black participants had higher pain severity and had significantly different age, work status, and comorbidity profiles. RMANOVA models also identified significant race-based differences in the response to the parent IMGV intervention. There was reduced pain severity in African American/Black subjects in the IMGV condition from baseline to 9 weeks. This change was not observed in White participants over this time period. However, there was a reduction in pain severity in White participants over the subsequent interval from 9 to 21 week where IMGV had no significant effect in African American/Black subjects during this latter time period.

Conclusion

Interactions between pain and racialization require further investigation to understand how race-based heterogeneity in the response to integrative medicine treatments for chronic pain contribute to the broader landscape of health inequity.

Racial Disparities in Pain Among Women with Fibromyalgia: Secondary Data Analysis of Severity, Interference with Function, and Response to Guided Imagery

Background: Fibromyalgia syndrome (FMS) is characterized by widespread persistent musculoskeletal pain. Mostly prevalent among White women, little is known about FMS in other population cohorts. This study examined secondary data of a racially diverse sample of women with FMS that were collected as part of a randomized controlled clinical trial that examined the effect of a complementary therapy intervention over the course of a 10-week guided imagery intervention to identify demographic, social, or economic differences in self-reported pain. Materials and Methods: The Brief Pain Inventory (BPI), which measures pain severity and interference, was administered to 72 women (21 Black and 51 Whites) at baseline, 6 and 10 weeks. Student's t tests and time series regression models examined racial difference in pain dimensions and treatment response. Regression models accounted for age, race, income, duration of symptoms, treatment group, pain at baseline, smoking, alcohol use, comorbid conditions, and time. Results: Black women experienced significantly higher pain severity (β = 5.52, standard deviation [SD] = 2.13) and interference (β = 5.54, SD = 2.74) than Whites (severity β = 4.56, SD = 2.08; interference β = 4.72, SD = 2.76) (interference: t = 1.92, p = 0.05; severity: t = 2.95, p = 0.00). Disparities persisted over time. Controlling for differences in age, income, and previous pain levels, Black women had 0.26 (standard error [SE] = 0.065) higher pain severity and 0.36 (SE = 0.078) higher interference than Whites. Low-income earners also experienced 2.02 (SE = 0.38) and 2.19 (SE = 0.46) higher pain severity and interference, respectively, than other earners. Results were robust to inclusion of comorbidities. Conclusions: Black women and low-income earners experienced significantly higher levels of pain severity and interference and a lower dose response to the intervention. Differentials were robust to inclusion of demographic, health, and behavioral characteristics. Findings suggest that external factors may contribute to pain perception among women with FMS.

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.

Rehabilitation therapy using the HUBER platform in chronic non-specific low back pain: a randomized controlled trial

BACKGROUND

Non-specific chronic low back pain (NSCLBP) refers to a complex condition that involves structural, biomechanical, cognitive, psychological, social, and lifestyle issues. First-line therapies include physical therapy and exercise, as well as psychological follow-up and pain medication.

AIM

The aim of this study was to assess the impact of a 6-week center-based program using a multi-axis motorized platform (HUBER) connected with force sensors, that allows the patients to execute isometric exercises on the spine flexion-to-extension ratio at 60 and 120°/s, pain, trunk flexibility, and disability.

DESIGN

The design of the study was prospective, active control, parallel-group, assessor-blinded, randomized controlled trial.

SETTING

The setting was outpatients physical therapy clinic.

POPULATION

The population analyzed presented NSCLBP.

METHODS

Seventy individuals with NSCLBP were randomized into 2 intervention arms (1:1 ratio): 1/standard rehabilitation group (STAND) with physiotherapy, balneotherapy and cycloergometer exercises and 2/HUBER rehabilitation group (HUB) with physiotherapy, balneotherapy and HUBER exercises. Both programs lasted 6 weeks, with 4 sessions of 2 hours each per week.

RESULTS

Each group reported statistically significant improvements on the isokinetic spine strength, flexibility of the trunk, lumbar joint mobility, muscular endurance of the trunk and of the lower limbs, pain score and disability (P<0.05). The spine flexion/extension ratio at 60˚/s improved similarly between groups (-22.23 for HUB, and -13.04 for STAND; P=0.178) with a greater effect size in HUB. Only HUB reported a significant improvement in the spine flexion-to-extension ratio at 120˚/s (from 87.3 to 78.6, P=0.012). HUB reported a greater decrease in the Oswestry Disability Index (-16.83) compared to STAND (-12.11), with a statistically significant effect between groups (P=0.036).

CONCLUSIONS

Exercises performed on the HUBER platform added to physiotherapy and balneotherapy are as effective as a standard rehabilitation program with physiotherapy, balneotherapy and cycloergometer exercises to improve isokinetic spine strength, lumbar joint mobility, flexibility and muscular endurance of the trunk and the lower limbs. In addition, exercising with the HUBER platform result in a greater reduction in disability compared to a standard rehabilitation program (clinicalTrials.gov: NCT05437016).

CLINICAL REHABILITATION IMPACT

A variety of intervention techniques, including supervised exercise and manual therapy are now used to manage persistent NSCLBP. The added value of the HUBER device on disability suggests that the platform could be beneficial.

A descriptive study of physical function and performance in older black men with low back pain

The purpose of this paper is to describe physical function and performance scores and examine the relationships between measures of physical performance in older Black men with low back pain. The Mobility, Aging, Pain, and Disparities study used a cross-sectional, observational design to objectively measure physical performance on the Short Physical Performance Battery (SPPB), the Back Performance Scale (BPS), and the 400-meter Walk Test along with subjective ratings of pain intensity in the past 24 hours. Sixty community-based Black men aged 61-87 (x̄= 70 ± 6) years had an average BPS score of 7.0 ± 4 and total score on the SPPB 8.5 ± 2.1. Average 400-meter Walk time was 6.3 ± 3.1 minutes. Men's average pain intensity in the past 24 hours was 5.7 ± 2, indicating moderate pain. In conclusion, older Black men with low back pain demonstrated low physical function scores and a higher level of disability.

Reference intervals and sources of variation of pressure pain threshold for quantitative sensory testing in a Japanese population

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer.

Toward a causal model of chronic back pain: Challenges and opportunities

Chronic low back pain (cLBP) afflicts 8. 2% of adults in the United States, and is the leading global cause of disability. Neuropsychiatric co-morbidities including anxiety, depression, and substance abuse- are common in cLBP patients. In particular, cLBP is a risk factor for opioid addiction, as more than 50% of opioid prescriptions in the United States are for cLBP. Misuse of these prescriptions is a common precursor to addiction. While associations between cLBP and neuropsychiatric disorders are well established, causal relationships for the most part are unknown. Developing effective treatments for cLBP, and associated co-morbidities, requires identifying and understanding causal relationships. Rigorous methods for causal inference, a process for quantifying causal effects from observational data, have been developed over the past 30 years. In this review we first discuss the conceptual model of cLBP that current treatments are based on, and how gaps in causal knowledge contribute to poor clinical outcomes. We then present cLBP as a "Big Data" problem and identify how advanced analytic techniques may close knowledge gaps and improve clinical outcomes. We will focus on causal discovery, which is a data-driven method that uses artificial intelligence (AI) and high dimensional datasets to identify causal structures, discussing both constraint-based (PC and Fast Causal Inference) and score-based (Fast Greedy Equivalent Search) algorithms.

The Experience of BIPOC Living with Chronic Pain in the USA: Biopsychosocial Factors that Underlie Racial Disparities in Pain Outcomes, Comorbidities, Inequities, and Barriers to Treatment

PURPOSE OF REVIEW

This review synthesizes recent findings related to the biopsychosocial processes that underlie racial disparities in chronic pain, while highlighting opportunities for interventions to reduce disparities in pain treatment among BIPOC.

RECENT FINDINGS

Chronic pain is a prevalent and costly public health concern that disproportionately burdens Black, Indigenous, and people of color (BIPOC). This unequal burden arises from an interplay among biological, psychological, and social factors. Social determinants of health (e.g., income, education level, and lack of access or inability to utilize healthcare services) are known to affect overall health, including chronic pain, and disproportionately affect BIPOC communities. This burden is exacerbated by exposure to psychosocial stressors (i.e., perceived injustice, discrimination, and race-based traumatic stress) and can affect biological systems that modulate pain (i.e., inflammation and pain epigenetics). Further, there are racial/ethnic disparities in pain treatment, perpetuating the cycle of undermanaged chronic pain among BIPOC.

Investigating Women's Health Behavior and Impact of Health Exercise on Low Back Pain Caused by Breast Size

Objectives: The breast size causes back pain in women of every age. Back pain is critical for women with increasing age as they gradually lose energy to carry large breasts. Medical advancement in surgery has introduced treatment for large breast sizes. Natural remedies are difficult to take for women to reduce their breast size. This objective of this cross-sectional research was to investigate the impact of health exercise on low back pain in women caused by increased breast size with moderating influence of health literacy and access to doctors. Methods: The primary data was randomly collected from women in gyms and parks focusing on factors that can account for improving the health of women by reducing their back pain. Results: Furthermore, the study contributes a significant model in the body of knowledge related to the health behavior of women concerning their low back pain. Conclusion: Following significant findings, the study has deliberated the theoretical implication that enriched the literature and practical implications to improve the health behavior of women and reduce the chances of low back pain caused by breast size. Finally, this research highlighted some future directions based on research limitations.

Applying the Rapid OPPERA Algorithm to Predict Persistent Pain Outcomes Among a Cohort of Women Undergoing Breast Cancer Surgery

Persistent postmastectomy pain after breast surgery is variable in duration and severity across patients, due in part to interindividual variability in pain processing. The Rapid OPPERA Algorithm (ROPA) empirically identified 3 clusters of patients with different risk of chronic pain based on 4 key psychophysical and psychosocial characteristics. We aimed to test this type of group-based clustering within in a perioperative cohort undergoing breast surgery to investigate differences in postsurgical pain outcomes. Women (N = 228) scheduled for breast cancer surgery were prospectively enrolled in a longitudinal observational study. Pressure pain threshold (PPT), anxiety, depression, and somatization were assessed preoperatively. At 2-weeks, 3, 6, and 12-months after surgery, patients reported surgical area pain severity, impact of pain on cognitive/emotional and physical functioning, and pain catastrophizing. The ROPA clustering, which used patients' preoperative anxiety, depression, somatization, and PPT scores, assigned patients to 3 groups: Adaptive (low psychosocial scores, high PPT), Pain Sensitive (moderate psychosocial scores, low PPT), and Global Symptoms (high psychosocial scores, moderate PPT). The Global Symptoms cluster, compared to other clusters, reported significantly worse persistent pain outcomes following surgery. Findings suggest that patient characteristic-based clustering algorithms, like ROPA, may generalize across diverse diagnoses and clinical settings, indicating the importance of "person type" in understanding pain variability. PERSPECTIVE: This article presents the practical translation of a previously developed patient clustering solution, based within a chronic pain cohort, to a perioperative cohort of women undergoing breast cancer surgery. Such preoperative characterization could potentially help clinicians apply personalized interventions based on predictions concerning postsurgical pain.

Disparities Exist in Physical Therapy Utilization and Time to Utilization Between Black and White Patients With Musculoskeletal Pain

OBJECTIVE

Black patients are less likely than White patients to receive physical therapy for musculoskeletal pain conditions. Current evidence, however, is limited to self-reported conditions and health services use. The purpose of this study was to use a large electronic health record database to determine whether a race disparity existed in use of physical therapy within 90 days of a new musculoskeletal diagnosis.

METHODS

Eligible patients (n = 52,384) were sampled from an Optum deidentified electronic health record database of 5 million adults distributed throughout the United States. In this database, patients were designated as "Black" and "White." Patients were eligible if they had a new diagnosis for musculoskeletal neck, shoulder, back, or knee pain between January 1, 2012, and December 31, 2017. Logistic regression and Cox proportional hazard models were computed before and after adjusting for covariates to estimate the association between race and receipt of physical therapy services within 90 days of musculoskeletal pain diagnoses.

RESULTS

Patients were on average 47.5 (SD = 14.9) years of age, 12.8% were Black, 87.2% were White, and 52.7% were female. Ten percent of Black patients and 15.5% of White patients received physical therapy services within 90 days of musculoskeletal pain diagnoses. After adjusting for covariates, White patients were 57% more likely (odds ratio = 1.57; 95% CI = 1.44-1.71) to receive physical therapy compared with Black patients and had significantly shorter time to physical therapy than Black patients (hazard ratio = 1.53; 95% CI = 1.42-1.66).

CONCLUSIONS

In a nationally distributed cohort, Black patients were less likely than White patients to utilize physical therapy and had a longer time to utilization of physical therapy for musculoskeletal pain.

IMPACT

These findings highlight the need to determine the mechanisms underlying the observed disparities and how these disparities influence health outcomes.

Influence of genetic variants on remifentanil sensitivity in Chinese women

WHAT IS KNOWN AND OBJECTIVE

Significant individual differences have been observed in pain sensitivity and analgesic effect of opioids. Previous studies have shown that genetic factors contributed to analgesics requirement obviously. Therefore, we investigated the role of genetic polymorphisms in the sensitivity to the analgesic effect of remifentanil in this study.

METHODS

One hundred thirty-seven patients undergoing gynaecological surgery were observed. Before procedures, we measured the basal pain threshold of each patient, including the pressure pain threshold and pressure pain tolerance threshold. Subsequently, patients received a continuous remifentanil infusion for 15 min at a constant rate of 0.2 μg/(kg min). The pain thresholds were measured again after the remifentanil infusion. Moreover, respiratory depression was estimated using oxygen saturation during infusion. DNA was extracted from peripheral venous blood and genotyped using SNaPshot technology.

RESULTS AND DISCUSSION

Polymorphisms were found in genes associated with the individual variation in analgesia. Participants carrying OPRM1 rs9397685 AA, ADRB1 rs1801253 CC, and GCH1 rs8007267 CC polymorphisms showed higher sensitivity to analgesic effect induced by remifentanil, and the participants carrying the OPRD1 rs2234918 TT showed lower sensitivity to remifentanil-related respiratory depression. Moreover, individual susceptibility to remifentanil increases with age.

WHAT IS NEW AND CONCLUSION

Gene variation in OPRM1 rs9397685 AA, ADRB1 rs1801253 CC, GCH1 rs8007267 CC, and OPRD1 rs2234918 TT were related to the conspicuous interindividual differences in the analgesia and respiratory depression of remifentanil, mainly by affecting the target protein receptors and relative metabolic enzymes.

Association between chronic low back pain and regular exercise, sedentary behaviour and mental health before and during COVID-19 pandemic: insights from a large-scale cross-sectional study in Germany

Background

Nonspecific chronic low back pain (CLBP) is a complex symptom with numerous possible causes and influencing factors. Understanding how modifiable factors affect the course of CLBP is important for preventing progression. As the COVID-19 pandemic has changed the lifestyle of many people, this study paper assessed whether it also changed the influence of modifiable lifestyle factors (regular exercise and sedentary behaviour) and mental health factors (anxiety and depression) on CLBP pain intensity and disability by comparing the strength of these associations before and during the pandemic. We hypothesised that the importance of regular physical activity and good mental health for CLBP patients would increase during the pandemic.

Methods

These questions were investigated in a cross-sectional study of insurance claims data and self-reported data from various questionnaires from 3,478 participants in a German CLBP health intervention (2014–2021) by calculating pre- and intra-pandemic odds ratios (OR) and 95% confidence intervals (CI) for each variable of interest and outcome. Potential confounders were also considered. Pandemic status was treated as an effect modifier. Based on the date of enrolment, participants were classified as “pre-pandemic” or “pandemic”.

Results

Regularly exercising ≥ 4 h/week significantly reduced the odds of high disability for men (OR 0.49, 95% CI 0.31 – 0.79, p = 0.003) and women (OR 0.30, 95% CI 0.14 – 0.563, p = 0.002) and reduced the probability of severe pain in women (OR 0.37, 95% CI 0.21 – 0.65, p < 0.001). Each one-point increase in PHQ-4 score for anxiety and depression increased the OR of high pain intensity by 1.25 points (95% CI 1.18 – 1.34, p < 0.001). A clear impact of COVID-19 lockdowns was observed. In individuals who exercised ≥ 4 h/week the OR of high disability was 0.57 (95% CI 0.36 – 0.92, p = 0.021) in the pre-pandemic group compared to 0.29 (95% CI 0.12 – 0.56, p = 0.002) in the pandemic group. The probability of high disability increased from an OR of 1.42 (95% CI 1.33 – 1.52, p < 0.001) per marginal increase in the PHQ-4 scale before the pandemic, to an OR of 1.73 (95% CI 1.58 – 1.89, p < 0.001) during the pandemic.

Conclusions

The magnitude of association of the factors that influenced high pain intensity and disability increased during the pandemic. On the one hand, the protective effect of regular exercising was greater in participants surveyed during lockdown. On the other hand, a higher risk through anxiety or depression during the lockdown was identified. An additional study with objective measures of sedentary behaviour and physical activity is needed to validate these results. More in-depth investigation of lockdown-induced associations between reduced daily physical activity, increased levels of anxiety and depression, and their effects on CLPB could also be worthwhile.

Trial registration

This study used routinely collected data from a CLBP intervention that was previously evaluated and registered in the German Registry of Clinical Trials under DRKS00015463 (04/09/2018). The original ethics approval, informed consent and self-reported questionnaire have remained unchanged and are still valid.

Osteoarthritis is positively associated with self-reported sleep trouble in older adults

BACKGROUND

Osteoarthritis (OA) is a leading cause of disability in older adults. Most research has focused on minimizing pain and maximizing physical function so as to maintain patient mobility preceding joint arthroplasty. However, few studies have formally studied the relationship between OA and sleep trouble, although it is clinically recognized that OA may affect sleep.

METHODS

The study was based on the National Health and Nutrition Examination Survey (NHANES) database from 2011-2018. Participants were defined as adults aged 60 years or older with diagnoses of OA and self-reported sleep trouble. Multivariable regression analyses were applied to assess the association between OA and sleep trouble, adjusting for age, sex, body mass index, race/ethnicity, education level, marital status, income, depression level, etc. RESULTS: This study included 4154 participants, consisting of the control group (n = 2966) and the OA group (n = 1188). OA individuals were 2.11 (95% CI 1.79-2.47, p < 0.001) times more likely to have sleep trouble compared with those without OA. On subgroup analyses, there was lower odds ratio value of sleep trouble in men compared with women, and in the highest income group compared with the other income groups.

CONCLUSIONS

OA was positively associated with sleep trouble in older adults, with different odds ratio values among different subgroups. Our results suggest that older adults with OA should be aggressively screened for sleep problems.

Effects of an Intensive 6-Week Rehabilitation Program with the HUBER Platform in the Treatment of Non-Specific Chronic Low Back Pain: A Pilot Study

Non-specific chronic low back pain (NSCLBP) is defined as a complex disorder involving structural, biomechanical, cognitive, psychological, social, and lifestyle factors. Non-pharmacological approaches such as exercise and physical therapy have been proposed in first-line treatments, along with psychological follow-up and pain medication if needed. Our objective was to evaluate the effectiveness of an intensive rehabilitation program with HUBER (a multi-axis motorized platform equipped with force sensors, allowing patients to perform physical exercises in an isometric mode) on the spine flexion-to-extension ratio at 60 and 120°/s, pain, and trunk flexibility in individuals with NSCLBP. Twelve participants underwent a clinical evaluation including isokinetic spine strength and participated in a 6-week rehabilitation program with HUBER 360 Evolution. The main findings of this pilot study show that the flexor/extensor ratios at 60°, the flexibility of the hamstring and quadriceps, and muscular endurance of the trunk, disability, and quality of life were significantly improved at the end of the rehabilitation program (p < 0.05). Low back pain and analgesic medication were also reduced. Exercising with the HUBER Platform seems to be effective in managing NSCLBP but a randomized study with a larger sample size and a control group is necessary.

The distinct longitudinal impact of pain catastrophizing on pain interference among youth living with sickle cell disease and chronic pain

Youth living with chronic sickle cell disease (SCD) pain are at risk for psychosocial distress and high levels of pain catastrophizing that contribute to functional impairment. This study aimed to identify the unique long-term impact of pain catastrophizing on pain impairment among youth with SCD. Youth with chronic SCD pain (N = 63, 10-18 years old, 58.3% female, 95.1% Black or African American) were recruited within comprehensive SCD clinics and completed a battery of measures at baseline and 4-months follow-up. A linear hierarchical regression examined baseline demographic and clinical characteristics (child SCD genotype, age, and average pain intensity), psychosocial functioning (anxiety, depression), and pain catastrophizing as predictors of pain interference at 4-months follow-up. Pain catastrophizing was the only unique predictor of pain interference at 4-months follow-up. Among youth with chronic SCD pain, pain catastrophizing warrants greater consideration as an important predictor that influences pain management and overall functioning.

Making Pain Research More Inclusive: Why and How

Current knowledge about mechanisms and interventions for pain has largely been derived from samples that are healthier, wealthier, younger, and more likely to be White than the general population. Failure to conduct inclusive pain research not only restricts generalizability and application of findings, but also hampers the discovery of mechanisms and the development of measures and interventions that are valid across population subgroups. Most of all, inclusive practices are critical to ensure that underrepresented groups derive equitable benefit from pain research. Here, we provide guidance for the pain research community on how to adopt inclusive research practices. We define "inclusion" to encompass a range of identities and characteristics, including racialized group/ethnicity, disability status, gender identity, sexual orientation, and age. We first describe principles relevant to promoting inclusion in pain research, including attention to: 1) stakeholder engagement; 2) structural factors underlying inequities; 3) the limitations of "disparity" research; 4) intersectionality; and 5) universal design. Next, we provide checklists with practical strategies for making studies more inclusive at each stage of the research process. We conclude by calling for system-level changes to ensure that the future of pain research is socially just, scientifically productive, and responsive to the needs of all people. PERSPECTIVE: This paper offers guidance on promoting inclusion of underrepresented groups in pain research. We describe principles relevant to conducting more inclusive research; eg, attention to stakeholder engagement, structural factors, and universal design. We provide checklists with practical strategies for inclusion at each stage of the research process.

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.

Primary care providers' experiences treating low back pain

CONTEXT

Our original work addresses the biological sex impact on low back pain (LBP) management and prognosis in primary care settings. To our knowledge, our study is the first in the United States to evaluate the differences in clinicians' approaches to LBP in the ambulatory setting specifically based on patient gender. Our findings suggest that there is a knowledge gap among primary care providers (PCPs) toward the potential impact of biological sex on LBP and a bias toward gender roles when counseling patients for home chores or occupational tasks. Further evaluation of this knowledge gap and its impact on LBP management and prognosis is recommended in US healthcare settings.

OBJECTIVES

This study aims to explore PCP experiences and practice patterns regarding LBP in females compared to males in US healthcare settings.

METHODS

We utilized a cross-sectional study design and convenience sampling. Data were collected anonymously utilizing a 27-item online survey sent periodically via email to PCPs working in Ohio. We had 58 responses for analysis; data were analyzed utilizing bivariate and multivariate analyses.

RESULTS

On average, approximately 9 out of 10 responding clinicians reported experiencing LBP. PCPs were not in agreement that LBP is different in women than men. Clinicians with a women's health, osteopathic, or sport's medicine background were more likely to agree that LBP is different in women than in men. PCPs were more likely to counsel female patients about pelvic floor exercises; however, their intake of present pelvic symptoms in LBP female patients is suboptimal. PCPs were more likely to counsel females for home chores than males, which is aligned with the perceived traditional gender roles among PCPs.

CONCLUSIONS

There may be a knowledge gap among PCPs toward the potential impact of biological sex on LBP and a bias toward gender roles when counseling patients for home chores or occupational tasks. Further investigation of this knowledge gap and counseling approaches is recommended to better bridge the gender disparity.

Responsiveness and minimal important change of the Pain Catastrophizing Scale in people with chronic low back pain undergoing multidisciplinary rehabilitation

BACKGROUND

The Pain Catastrophizing Scale (PCS), a widely used tool to assess catastrophizing related to spinal disorders, shows valid psychometric properties in general but the minimal important change (MIC) is still not determined.

AIM

The aim of this study was to assess responsiveness and MIC of the PCS in individuals with chronic low back pain (LBP) undergoing multidisciplinary rehabilitation.

DESIGN

Prospective observational study.

SETTING

The setting was outpatient rehabilitation hospital.

POPULATION

Two hundred and five patients with chronic LBP.

METHODS

Before and after an 8-week multidisciplinary rehabilitation program, 205 patients completed the Italian version of the PCS (PCS-I). We calculated the PCS-I responsiveness by distribution-based methods (effect size [ES], standardized response mean [SRM], and minimum detectable change [MDC]) and anchor-based methods [receiver operating characteristic (ROC) curves]. After the program, participants completed a 7-point global perceived effect scale (GPE), based on which they were classified as "improved" vs. "stable." ROC curves computed the best cut-off level (taken as the MIC) between the two groups. ROC analysis was also performed on subgroups according to patients' baseline PCS scores.

RESULTS

ES, SRM and MDC were 0.71, 0.67 and 7.73, respectively. ROC analysis yielded an MIC of 8 points (95% confidence interval [CI]: 6-10; area under the curve [AUC]: 0.88). ROC analysis of the PCS subgroups confirmed an MIC of 8 points (95%CI: 6-10) for no/low catastrophizers (score <30, N.=159; AUC: 0.90) and indicated an MIC of 11 points (95%CI: 8-14) for catastrophizers (score >30, N.=33; AUC: 0.84).

CONCLUSIONS

The PCS-I showed good ability to detect patient-perceived clinical changes in chronic LBP postrehabilitation. The MIC values we determined provide a benchmark for assessing individual improvement in this clinical context.

CLINICAL REHABILITATION IMPACT

The present study calculated - in a sample of people with chronic LBP - the responsiveness and MIC of the PCS. These values increase confidence in interpreting score changes, enhancing their meaningfulness for both research and clinical contexts.

Racial Differences in Pain, Nutrition, and Oxidative Stress

Investigating the disproportionate rates of chronic pain and their related comorbidities between Black and non-Hispanic White (White) individuals is a growing area of interest, both in the healthcare community and in general society. Researchers have identified racial differences in chronic pain prevalence and severity, but still very little is known about the mechanisms underlying them. Current explanations for these differences have primarily focused on socioeconomic status and unequal healthcare between races as causal factors. Whereas these factors are informative, a racial gap still exists between Black and White individuals when these factors are controlled for. One potential cause of this racial gap in chronic pain is the differences in nutrition and dietary intake between groups. Certain foods play a key role in the inflammatory and oxidative stress pathways in the human body and could potentially influence the severity of the pain experience. Here, we review the previous literature on the surrounding topics and propose a potential mechanism to explain racial differences in the chronic pain population, based on established racial differences in diet and oxidative stress.

Differential DNA methylation in Black and White individuals with chronic low back pain enrich different genomic pathways

Compared to Non-Hispanic Whites (NHWs), individuals who self-identify as Non-Hispanic Blacks (NHBs) in the United States experience more severe and disabling chronic low back pain (cLBP). We hypothesized that differences in DNA methylation (DNAm) play a role in racial disparities in cLBP.

PURPOSE

To determine the relationship between DNAm levels and racial group differences in adults with cLBP. Our study's secondary purpose was to perform a race-stratified comparison of adults with cLBP and pain-free controls and identify functional genomic pathways enriched by annotated differentially methylated genes.

PATIENTS AND METHODS

We recruited 49 NHBs and 49 NHWs (49 cLBP and 49 pain-free controls, PFCs), analyzed DNAm from whole blood using reduced representation bisulfite sequencing, and identified enriched genomic pathways.

RESULTS

Among participants with cLBP, we identified 2873 differentially methylated loci (DML; methylation differences of at least 10% and p < 0.0001), many of which were annotated to genes of importance to pain pathology. These DMLs significantly enriched pathways to involved in nociception/pain processing (Dopamine-DARPP32 Feedback in cAMP signaling, GABA Receptor Signaling, Opioid Signaling) and neuronal differentiation (e.g., Calcium Signaling, Axon Guidance Signaling, and Endocannabinoid Neuronal Synapse). Our race stratified analyses of individuals with cLBP versus PFCs revealed 2356 DMLs in NHBs and 772 DMLs in NHWs with p < 0.0001 and > 10% methylation difference. Ingenuity Pathway Analysis revealed that many pathways of significance to pain such as Corticotropin Releasing Hormone Signaling, White Adipose Tissue Browning, and GABA Receptor Signaling pathways, were more significant in NHBs than NHWs.

CONCLUSION

Even though an individual's self-identified race is a social construct, not a biological variable, racism associated with that classification affects virtually every aspect of life, including disease risk. DNAm induced alterations in stress signaling pathways may explain worse pain outcomes in NHBs.

Low back pain prevalence, beliefs and treatment-seeking behaviour in multi-ethnic Suriname

Objectives

The aims were to determine, for the first time, the prevalence of low back pain (LBP) in urban and rural communities and to assess back beliefs and treatment-seeking behaviour in Suriname, a multi-ethnic country in the Caribbean community.

Methods

A cross-sectional community-based survey using the Community Oriented Program for the Control of Rheumatic Diseases methodology was performed between April 2016 and July 2017. Information was collected on LBP prevalence and LBP-related treatment seeking, beliefs about LBP [Back Beliefs Questionnaire (BBQ)], level of disability (Oswestry Disability Index) and the risk of developing persistent disabling pain (Start Back Screening Tool).

Results

A total of 541 out of 2902 individuals reported current acute or chronic LBP. It was more prevalent in urban (20.2%) than in rural (13.7%) communities, especially in females and older adults (>55 years of age). Individuals from rural areas [median BBQ = 18.00 (14.00-22.00)] had significantly more negative beliefs than the urban population [median BBQ = 25.00 (19.00-31.00); P < 0.001]. Maroons displayed more negative beliefs than Creole (P = 0.040), Hindustani (P < 0.001), Javanese (P < 0.001) and mixed ethnicity (P < 0.001) groups. At least 75% of the LBP population sought care, especially from a western health-care practitioner. Seeking treatment and having a higher risk of developing persistent disabling pain was significantly associated with more disability (P < 0.001). Age ≥45 years (P < 0.001), Indigenous ethnicity (P < 0.05) and functional disability (P < 0.001) were factors influencing treatment seeking.

Conclusion

Low back pain is a prevalent health problem in the Surinamese urban community, especially in older adults and among females. Most individuals experiencing LBP visited a western health-care practitioner and had more negative beliefs compared with other communities.

The role of negative emotions in sex differences in pain sensitivity

Pain perception varies widely among individuals due to the varying degrees of biological, psychological, and social factors. Notably, sex differences in pain sensitivity have been consistently observed in various experimental and clinical investigations. However, the neuropsychological mechanism underlying sex differences in pain sensitivity remains unclear. To address this issue, we quantified pain sensitivity (i.e., pain threshold and tolerance) using the cold pressure test and negative emotions (i.e., pain-related fear, pain-related anxiety, trait anxiety, and depression) using well-established questionnaires and collected magnetic resonance imaging (MRI) data (i.e., high-resolution T1 structural images and resting-state functional images) from 450 healthy subjects. We observed that, as compared to males, females exhibited lower pain threshold and tolerance. Notably, sex differences in pain sensitivity were mediated by pain-related fear and anxiety. Specifically, pain-related fear and anxiety were the complementary mediators of the relationship between sex and pain threshold, and they were the indirect-only mediators of the relationship between sex and pain tolerance. Besides, structural MRI data revealed that the amygdala subnuclei (i.e., the lateral and basal nuclei in the left hemisphere) volumes were the complementary mediators of the relationship between sex and pain-related fear, which further influenced pain sensitivity. Altogether, our results provided a comprehensive picture of how negative emotions (especially pain-related negative emotions) and related brain structures (especially the amygdala) contribute to sex differences in pain sensitivity. These results deepen our understanding of the neuropsychological underpinnings of sex differences in pain sensitivity, which is important to tailor a personalized method for treating pain according to sex and the level of pain-related negative emotions for patients with painful conditions.

The predictors for altered central pain modulation in individuals with nonspecific chronic low back pain: A systematic review

BACKGROUND

Research suggests that the prognosis of chronic nonspecific low back pain is poor when there is an alteration in the central pain processing pathway. This alteration creates a cascade of events, leading to poor outcomes. An overview of the predictors which increase this heightened pain perception is needed.

OBJECTIVES

To review the studies identifying predictors for altered central main modulation in individuals with nonspecific chronic low back pain.

DESIGN

This is a systematic review.

METHODS

PubMed, Cochrane Library, Science Direct, Scopus, Ovid, Embase, Web of Science, and CINAHL were searched from inception to 25th May 2021. Titles, abstracts, and full text were searched for eligible articles, which met the set criteria. Research articles that have employed outcome measure specific to altered central pain modulation and assessed at least one predictor were included.

RESULTS

Six studies (n = 1389) were included in this review. The following five groups of predictors were identified: (1) psychological, (2) psychosocial (education, employment status, pain catastrophizing, and kinesiophobia), (3) sensory profile, (4) gender, and (5) others (illness and cognitive factors). Positive evidence of association was found for psychological predisposition and psychosocial (pain catastrophizing and employment and education status), whereas no evidence of association was found for kinesiophobia and cognitive factors.

CONCLUSION

This review identified the predictors for altered central pain modulation in chronic nonspecific low back pain. This alteration could be responsible for the suspected poor outcomes even post treatment. Furthermore, the knowledge of predictors could potentially aid the therapist in planning a treatment regime when poor outcomes are suspected.

Race, Social Status, and Depressive Symptoms: A Moderated Mediation Analysis of Chronic Low Back Pain Interference and Severity

BACKGROUND

Chronic low back pain (cLBP) is the leading cause of disability, with a significant societal cost. It disproportionately affects non-Hispanic blacks and individuals of lower socioeconomic status. The biopsychosocial framework has been used to study and manage cLBP, yet disparities persist.

OBJECTIVE

The objective of this study was to assess whether self-identified race moderated the relationship between perceived social status and cLBP outcomes (pain interference and pain severity) and investigate whether race moderated the indirect relationship between perceived social status and pain outcomes via depressive symptoms.

METHODS

Fifty-seven blacks and 48 whites with cLBP were recruited as part of a large ongoing study. Depressive symptoms, objective and subjective measures of socioeconomic status, and pain outcomes were measured. Hayes' moderated mediation model was used to estimate conditional direct and indirect relationship between these variables.

RESULT

On average black participants reported significantly more pain interference (4.12 [SD=2.65] vs. 2.95 [SD=2.13]) and severity (5.57 [SD=2.27] vs. 3.99 [SD=1.99]) than white participants, (P<0.05). Race moderated the association between perceived social status and pain interference: higher social status decreases pain interference for white participants, but that trend was not observed in black participants. Moreover, race moderated association of perceived social status with depressive symptoms (P<0.001); which mediates the effects of perceived social status on pain outcomes.

CONCLUSION

Higher perceived social status is associated with less severe depressive symptoms, which in turn is associated with less pain severity and less pain interference for whites but not for blacks with cLBP.

The effects of chair intervention on lower back pain, discomfort and trunk muscle activation in office workers: a systematic review

Objectives. The chair is a standard piece of workstation equipment in an office. Previous studies showed that a suitable chair may reduce musculoskeletal symptoms. This review investigated the effect of chair intervention on lower back pain (LBP), discomfort and trunk muscle activation among office workers. Methods. Five electronic databases from 1980 to May 2020 were searched for relevant randomized and non-randomized controlled trials. The methodological quality of the included studies was assessed using the 13-item Cochrane risk of bias tool. Quality of evidence was assessed and rated according to Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines. Results. Two randomized controlled trials, 10 repeated-measures studies and two prospective cohort studies were included in this review. Nine studies were rated as high quality. The results indicated very low-quality to low-quality evidence for the conflicting effect of chair intervention on pain and discomfort reduction as well as trunk muscle activation among office workers. When stratified by chair type, the level of evidence for health benefits derived from any type of chair was still of very low to low quality. Conclusion. Unless supplementary high-quality studies provide different evidence, chair interventions are not recommended to reduce LBP or discomfort and activate trunk muscles.

Higher Pain Sensitivity Predicts Efficacy of a Wearable Transcutaneous Electrical Nerve Stimulation Device for Persons With Fibromyalgia: A Randomized Double-Blind Sham-Controlled Trial

OBJECTIVES

This study investigated the efficacy of a transcutaneous electrical nerve stimulation (TENS) device (Quell®) for persons with symptoms due to fibromyalgia (FM).

MATERIALS AND METHODS

One hundred nineteen (N = 119) subjects were randomly assigned to use an active (N = 62) or sham (N = 57) TENS for three months. All subjects completed baseline questionnaires and were administered quantitative sensory testing (QST). Subjects completed the Patients' Global Impression of Change (PGIC, primary outcome measure) and other mailed questionnaires (secondary outcome measures) at six weeks and three months.

RESULTS

The subjects averaged 50.4 ± 13.5 years of age, 93.3% were female, and 79.8% were Caucasian. Most showed benefit from using the TENS, but no differences between groups were found on the primary outcome measure after three months (active 3.87 ± 1.85, sham 3.73 ± 1.80, 95% confidence interval [CI] [-0.60, 0.88], p = 0.707). Those with more hypersensitivity showed most improvement on the PGIC at six weeks (0.22, 95% CI [0.01, 0.43], p = 0.042) and three months (0.20, 95% CI [0.00, 0.41], p = 0.049) and among those with higher sensitivity based on QST, the active TENS group showed the most benefit with TENS compared with the sham treatment (1.20, 95% CI [0.22, 2.18], p = 0.017). No TENS-related serious adverse events were reported. Subjects in the sham group correctly identified their treatment 87.5% of the time, while, surprisingly, subjects in the active group correctly identified their treatment only 17.4% of the time.

CONCLUSION

This study found no differences between those who were exposed to maximal-frequency active stimulation or minimal-frequency sham stimulation from a wearable TENS in reducing FM-related symptoms. However, those with greater hypersensitivity showed most benefit from TENS. Additional studies to help determine the role individual differences play in the use of TENS in managing FM-related symptoms are needed.

A Mediation Appraisal of Catastrophizing, Pain-Related Outcomes, and Race in Adults With Knee Osteoarthritis

The current cross-sectional study investigates whether pain catastrophizing mediates the relationship between ethnicity/race and pain, disability and physical function in individuals with knee osteoarthritis. Furthermore, this study examined mediation at 2-year follow-up. Participants included 187 community-dwelling adults with unilateral or bilateral knee pain who screened positive for knee osteoarthritis. Participants completed several self-reported pain-related measures and pain catastrophizing subscale at baseline and 2-year follow-up. Non-Hispanic Black (NHB) adults reported greater pain, disability, and poorer functional performance compared to their non-Hispanic White (NHW) counterparts (Ps < .05). NHB adults also reported greater catastrophizing compared to NHW adults. Mediation analyses revealed that catastrophizing mediated the relationship between ethnicity/race and pain outcome measures. Specifically, NHB individuals reported significantly greater pain and disability, and exhibited lower levels of physical function, compared to NHW individuals, and these differences were mediated by higher levels of catastrophizing among NHB persons. Catastrophizing was a significant predictor of pain and disability 2-years later in both ethnic/race groups. These results suggest that pain catastrophizing is an important variable to consider in efforts to reduce ethnic/race group disparities in chronic pain. The findings are discussed in light of structural/systemic factors that may contribute to greater self-reports of pain catastrophizing among NHB individuals. PERSPECTIVE: The current study examines whether pain catastrophizing mediates the relationship between ethnicity/race and OA-related pain, disability, and functional impairment at baseline and during a 2-year follow-up period in non-Hispanic Black and non-Hispanic White adults with knee pain. These results point to the need for interventions that target pain catastrophizing.

Racial and Ethnic Disparities in the Treatment of Chronic Pain

OBJECTIVE

To summarize the current literature on disparities in the treatment of chronic pain.

METHODS

We focused on studies conducted in the United States and published from 2000 and onward. Studies of cross-sectional, longitudinal, and interventional designs were included.

RESULTS

A review of the current literature revealed that an adverse association between non-White race and treatment of chronic pain is well supported. Studies have also shown that racial differences exist in the long-term monitoring for opioid misuse among patients suffering from chronic pain. In addition, a patient's sociodemographic profile appears to influence the relationship between chronic pain and quality of life. Results from interventional studies were mixed.

CONCLUSIONS

Disparities exist within the treatment of chronic pain. Currently, it is unclear how to best combat these disparities. Further work is needed to understand why disparities exist and to identify points in patients' treatment when they are most vulnerable to unequal care. Such work will help guide the development and implementation of effective interventions.

Medial Prefrontal Transcranial Direct Current Stimulation Aimed to Improve Affective and Attentional Modulation of Pain in Chronic Low Back Pain Patients

Chronic low back pain (CLBP) is often without clear underlying pathology. Affective disturbance and dysfunctional pain mechanisms, commonly observed in populations with CLBP, have, therefore, been suggested as potential contributors to CLBP development and maintenance. However, little consensus exists on how these features interact and if they can be targeted using non-invasive brain stimulation. In this pilot trial, 12 participants completed two phases (Active or Sham) of high-definition transcranial direct current stimulation (HD-tDCS) to the medial prefrontal cortex, applied for 20 min on three consecutive days. Clinical pain ratings, questionnaires, and sensitivity to painful cuff pressure were completed at baseline, then 4 trials of conditioned pain modulation (CPM; alone, with distraction using a Flanker task, with positive affect induction, and with negative affect induction using an image slideshow) were performed prior to HD-tDCS on Day 1 and Day 4 (24 h post-HD-tDCS). At baseline, attentional and affective manipulations were effective in inducing the desired state (p < 0.001) but did not significantly change the magnitude of CPM-effect. Active HD-tDCS was unable to significantly alter the magnitude of the shift in valence and arousal due to affective manipulations, nor did it alter the magnitude of CPM under any basal, attentional, or affective manipulation trial significantly on Day 4 compared to sham. The CPM-effect was greater across all manipulations on Day 1 than Day 4 (p < 0.02) but also showed poor reliability across days. Future work is needed to expand upon these findings and better understand how and if HD-tDCS can be used to enhance attentional and affective effects on pain modulation.

Women, opioid use and addiction

In the midst of the current coronavirus pandemic, the United States continues to struggle with an ongoing opioid epidemic, initially fueled by widespread prescribing of opioid medications during the 1990s. The primary reason for prescribing opioids is to treat pain. Women have more acute and chronic pain and have been prescribed these drugs in significantly greater numbers than men. Comparison of women and men with chronic pain also shows that women receive the majority of prescription opioids, and the use of these prescribed medications became the major pathway to misuse and addiction for women. Yet, recognition of the extent of women's exposure to opioids and the attendant consequences has been limited. Attempts to stem the overall tide of the epidemic focused on reducing the availability of prescription opioids. However, as these medications became more difficult to obtain and treatment opportunities were limited, many turned to other synthetic opioids, such as heroin and fentanyl. Thus, the public health crisis of opioid addiction has endured. This paper highlights the importance of understanding differences among women and men in opioid use and its biological and psychosocial effects to advance the gender-based treatment approaches and effective public health policy.

Greater mechanical temporal summation of pain in Latinx-Americans and the role of adverse life experiences

Supplemental Digital Content is Available in the Text.

Latinx-Americans showed greater temporal summation, adversity, and adversity correlates relative to non-Hispanic Whites. Discrimination and lifespan social status change inversely related to summation for Latinx-Americans.

Introduction:

Adverse life experiences disproportionately impact Latinx-Americans and are related to greater chronic pain rates. However, little is known about how adversities interact with central pain mechanisms for the development of later pain among Latinx-Americans.

Objectives:

The current study examined the relationship between adverse life experiences (eg, trauma and ethnic discrimination) and correlates (eg, social status) with mechanical temporal summation of pain (a proxy measure of central sensitization) between pain-free U.S. native Latinx (n = 65) and non-Hispanic White (NHW) (n = 51) adults.

Methods:

Participants completed self-report adverse life experience and correlational measures regarding childhood and adulthood and a mechanical temporal summation protocol.

Results:

Relative to NHWs, Latinx-Americans reported experiencing significantly greater trauma, discrimination, and lower social status during childhood and adulthood, along with greater temporal summation. Contrary to hypotheses, recent and lifetime experiences of ethnic discrimination significantly correlated with less temporal summation among Latinx-Americans. Decreases in objective and subjective social status across the lifespan (childhood to present day) correlated with greater temporal summation for Latinx-Americans. However, r-to-z transformation analyses confirmed that significant adversity and social status correlations observed among the Latinx group did not significantly differ from NHW participants.

Conclusions:

The present findings highlight the complex association between adverse experiences, adverse experience risk factors, and pain for Latinx-Americans. Given the disproportion of experienced pain and adversity among Latinx-Americans, the current findings suggest that a better understanding of the unique adversities for this sample may help elucidate the mechanisms underlying the relationship between adversities, adversity correlates, and pain risk for Latinx-Americans.

Pain relief for osteoarthritis through combined treatment (PROACT): Protocol for a randomized controlled trial of mindfulness meditation combined with transcranial direct current stimulation in non-Hispanic black and white adults with knee osteoarthritis

Knee osteoarthritis (OA) is a leading cause of late life pain and disability, and non-Hispanic black (NHB) adults experience greater OA-related pain and disability than non-Hispanic whites (NHWs). Recent evidence implicates psychosocial stress, cognitive-attentional processes, and altered central pain processing as contributors to greater OA-related pain and disability among NHBs. To address these ethnic/race disparities, this clinical trial will test whether a mindfulness intervention (Breathing and Attention Training, BAT) combined with transcranial direct current stimulation (tDCS) will enhance pain modulatory balance and pain-related brain function, reduce clinical pain, and attenuate ethnic differences therein, among NHBs and NHWs with knee OA. Participants will complete assessments of clinical pain, function, psychosocial measures, and quantitative sensory testing (QST), including mechanical temporal summation and conditioned pain modulation. Neuroimaging will be performed to examine pain-related brain structure and function. Then, participants will be randomized to one of four groups created by crossing two BAT conditions (Real vs. Sham) with two tDCS conditions (Real vs. Sham). Participants will then undergo five treatment sessions during which the assigned BAT and tDCS interventions will be delivered concurrently for 20 min over one week. After the fifth intervention session, participants will undergo assessments of clinical pain and function, QST and neuroimaging identical to the pretreatment measures, and monthly follow-up assessments of pain will be conducted for three months. This will be the first study to determine whether mindfulness and tDCS treatments will show additive or synergistic effects when combined, and whether treatment effects differ across ethnic/race groups.

Pain catastrophizing and distress intolerance: prediction of pain and emotional stress reactivity

Exposure to stress is associated with poor outcomes in people with chronic pain. Dispositional variables, such as pain catastrophizing and distress intolerance, may impact reactivity to stressors. Importantly, these variables can be modified with treatment. The aim of this study was to investigate whether pain catastrophizing and distress intolerance were associated with tolerance of a pain stressor or a psychosocial stressor, and heightened negative affect following these stressors. A sample of 50 adults with chronic pain completed self-report measures and pain and psychosocial stress inductions. Results indicated that pain catastrophizing was associated with heightened anxiety during pain induction. Distress intolerance was associated with negative affect following a psychosocial stressor, and with poorer tolerance of the psychosocial stressor. Pain catastrophizing and distress intolerance are related factors, however, they exhibit distinct associations with amplification of pain and psychosocial stress reactivity. These variables may be important treatment targets in people with chronic pain.

Disentangling trait versus state characteristics of the Pain Catastrophizing Scale and the PHQ-8 Depression Scale

BACKGROUND

Research on the role of trait versus state characteristics of a variety of measures among persons experiencing pain has been a focus for the past few decades. Studying the trait versus state nature of the Pain Catastrophizing Scale (PCS) and the Patient Health Questionnaire (PHQ-8) depression scale would be highly informative given both are commonly measured in pain populations and neither scale has been studied for trait/state contributions.

METHODS

The PHQ-8 and PCS were obtained on persons undergoing knee arthroplasty at baseline, 2-, 6- and 12-month post-surgery (N = 402). The multi-trait generalization of the latent trait-state model was used to partition trait and state variability in PCS and PHQ-8 item responses simultaneously. A set of variables were used to predict trait catastrophizing and trait depression.

RESULTS

For total scores, the latent traits and latent states explain 63.2% (trait = 43.2%; state = 20.0%) and 50.2% (trait = 29.4%; state = 20.8%) of the variability in PCS and PHQ-8, respectively. Patients with a high number of bodily pain sites, high levels of anxiety, young patients and African-American patients had high levels of trait catastrophizing and trait depression. The PCS and the PHQ-8 consist of both enduring trait and dynamic state characteristics, with trait characteristics dominating for both measures.

CONCLUSION

Clinicians and researchers using these scales should not assume the obtained measurements solely reflect either trait- or state-based characteristics.

SIGNIFICANCE

Clinicians and researchers using the PCS or PHQ-8 scales are measuring both state and trait characteristics and not just trait- or state-based characteristics.

Self-Efficacy and Multisite Pain Predictors among Economically Disadvantaged Women with Back Pain

BACKGROUND

Chronic low back pain (CLBP) prevalence is higher among women and those with low socioeconomic status. Without adequate self-efficacy and subsequent self-management, patients gradually develop chronic multisite pain after one year of having CLBP alone.

AIM

This study investigated the predictors of self-efficacy and multisite pain among adult, economically disadvantaged women, where pain prevalence is higher.

DESIGN

Cross-sectional, descriptive study.

SETTING

Pain management center.

SUBJECTS

Participants (n = 50) with primary diagnosis of chronic low back pain.

METHODS

After Institutional Review Board approval, data collection was conducted using valid and reliable instruments measuring several variables. Controlling for age and race, multiple linear regression was used for analyses.

RESULTS AND CONCLUSIONS

For all predictors of self-efficacy, a significant regression equation was identified (p < .01) with R2 of .413 and variance of .643. Pain catastrophizing was a significant individual predictor (p < .05). A significant regression equation was also found for all predictors of multisite pain (p < .001) with R2 of .528 and variance of .726. Individual predictors (p < .05) were age, physical function, and numbers of pain treatments and chronic medical conditions. Study findings suggest that significant predictors can be key to advancing pain research, education, practice, and healthcare policy toward improving pain management. Particularly among this population, pain catastrophizing needs to be targeted in pain management. To minimize development of multisite pain, further investigation of identified predictors including number of chronic medical conditions and pain treatments received are necessary. Multimodal, but targeted approaches addressing these predictors are recommended, instead of costly, indiscriminate multimodal therapy. Targeted interventions can help reduce pain care disparities among socioeconomically disadvantaged women, identify high risk groups for prompt intervention, facilitate better pain response to treatments, and minimize further disability.

Pain thresholds and intensities of CRPS type I and neuropathic pain in respect to sex

BACKGROUND AND AIMS

Healthy women have generally been found to have increased experimental pain perception and chronic pain has a higher prevalence in female as compared to male patients. However, no study has investigated whether pain intensity and pain perception thresholds are distinct or similar between sexes within various chronic pain entities. We investigated whether average pain intensities and pain thresholds assessed using quantitative sensory testing (QST) differed between women and men suffering from three distinct chronic pain conditions: Complex Regional Pain Syndrome (CRPS type I), peripheral nerve injury (PNI) or polyneuropathy (PNP), as compared to paired healthy volunteers.

METHODS

QST data of 1,252 patients (669 female, 583 male) with PNI (n = 342), PNP (n = 571) or CRPS (n = 339), and average pain intensity reports from previously published studies were included. Absolute and z-values (adjusted for age and body region) of cold, heat, pressure (PPT) and pinprick pain thresholds were compared in generalized linear models with aetiology, duration of underlying pain disease and average pain intensity as fixed effects.

RESULTS

Average pain intensity during the past four weeks did not differ between women and men, in both mean and range. In women absolute pain thresholds for cold, heat and pinprick were lower than in males across all diagnoses (p < .05). However, after z-transformation these differences disappeared except for PPT in CRPS (p = .001).

DISCUSSION

Pain thresholds in patients show only minor sex differences. However, these differences mimic those observed in healthy subjects and do not seem to be linked to specific pathophysiological processes.

SIGNIFICANCE

Female healthy participants and female patients with neuropathic pain conditions or CRPS I report lower pain thresholds compared to males, but pain intensity is similar and there is no sex difference in the extent to which the thresholds are altered in neuropathic pain or CRPS. Thus, the sex differences observed in various chronic pain conditions mimic those obtained in healthy participants, indicating that these differences are not linked to specific pathophysiological processes and are of minor clinical relevance.

Alcohol and Pain: A Translational Review of Preclinical and Clinical Findings to Inform Future Treatment Strategies

Alcohol use disorder (AUD) and chronic pain are enduring and devastating conditions that share an intersecting epidemiology and neurobiology. Chronic alcohol use itself can produce a characteristic painful neuropathy, while the regular analgesic use of alcohol in the context of nociceptive sensitization and heightened affective pain sensitivity may promote negative reinforcement mechanisms that underlie AUD maintenance and progression. The goal of this review was to provide a broad translational framework that communicates research findings spanning preclinical and clinical studies, including a review of genetic, molecular, behavioral, and social mechanisms that facilitate interactions between persistent pain and alcohol use. We also consider recent evidence that will shape future investigations into novel treatment mechanisms for pain in individuals suffering from AUD.