Differences in Clinical Pain and Experimental Pain Sensitivity Between Asian Americans and Whites With Knee Osteoarthritis

Epidemiology of osteoarthritis: literature update 2022-2023

PURPOSE OF REVIEW

This review highlights recently published studies on osteoarthritis (OA) epidemiology, including topics related to understudied populations and joints, imaging, and advancements in artificial intelligence (AI) methods.

RECENT FINDINGS

Contemporary research has improved our understanding of the burden of OA in typically understudied regions, including ethnic and racial minorities in high-income countries, the Middle East and North Africa (MENA) and Latin America. Efforts have also been made to explore the burden and risk factors in OA in previously understudied joints, such as the hand, foot, and ankle. Advancements in OA imaging techniques have occurred alongside the developments of AI methods aiming to predict disease phenotypes, progression, and outcomes.

SUMMARY

Continuing efforts to expand our knowledge around OA in understudied populations will allow for the creation of targeted and specific interventions and inform policy changes aimed at reducing disease burden in these groups. The burden and disability associated with OA is notable in understudied joints, warranting further research efforts that may lead to effective therapeutic options. AI methods show promising results of predicting OA phenotypes and progression, which also may encourage the creation of targeted disease modifying OA drugs (DMOADs).

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.

Psychophysics of Pain: A Methodological Introduction

For over 100 years, psychophysics ..÷ the scientific study between physical stimuli and sensation ... has been successfully employed in numerous scientific and healthcare disciplines, as an objective measure of sensory phenomena. This manuscript provides an overview of fundamental psychophysical concepts, emphasizing pain and research application..÷defining common terms, methods, and procedures.Psychophysics can provide systematic and objective measures of sensory perception that can be used by nursing scientists to explore complex, subjective phenomena..÷such as pain perception. While there needs to be improved standardization of terms and techniques, psychophysical approaches are diverse and may be tailored to address or augment current research paradigms. The interdisciplinary nature of psychophysics..÷like nursing..÷provides a unique lens for understanding how our perceptions are influenced by measurable sensations. While the quest to understand human perception is far from complete, nursing science has an opportunity to contribute to pain research by using the techniques and methods available through psychophysical procedures.

A historical review of pain disparities research: Advancing toward health equity and empowerment

BACKGROUND AND PURPOSE

This theory-guided review draws on 30 years of published data to examine and interrogate the current and future state of pain disparities research.

METHODS

Using the Hierarchy of Health Disparity Research framework, we synthesize and present an overview of "three generations" of pain disparities scholarship, while proposing directions for adopting a "fourth generation" that redefines, explains, and theorizes future pain disparities research in a diverse society.

DISCUSSION

Prior research has focused on describing the scope of disparities, and throughout the historical context of human existence, racialized groups have been subjected to inadequate pain care. It is imperative that research not only illuminates existing problems but also provides solutions that can be implemented and sustained across varying social milieus.

CONCLUSION

We must invest in new theoretical models that expand on current perspectives and ideals that position all individuals at the forefront of justice and equity in their health.

Elucidating factors contributing to disparities in pain-related experiences among adults with or at risk for knee osteoarthritis

Background and purpose

We and others have reported ethnic/race group differences in clinical pain, physical function, and experimental pain sensitivity. However, recent research indicates that with consideration for socioenvironmental factors, ethnicity/race differences become less or non-significant. Understanding of factors contributing to pain inequities are needed. Guided by the NIA and NIMHD Health Disparities Research Frameworks, we evaluate the contributions of environmental and behavioral factors on previously reported ethnic/race group differences in: (1) clinical pain, (2) physical function, and (3) experimental pain in individuals with knee pain.

Methods

Baseline data from Understanding of Pain and Limitations in Osteoarthritis Disease (UPLOAD) and UPLOAD-2 studies were analyzed. Participants were adults 45 to 85 years old who self-reported as non-Hispanic white (NHW) or black (NHB) with knee pain. A health assessment and quantitative sensory testing were completed. Sociodemographics, environmental, health, clinical and experimental pain, and physical functioning measures were included in nested regressions.

Results

Pooled data from 468 individuals, 57 ± 8 years of age, 63% women, and 53% NHB adults. As NHB adults were younger and reported greater socioenvironmental risk than the NHW adults, the term sociodemographic groups is used. With inclusion of recognized environmental and behavioral variables, sociodemographic groups remained a significant predictor accounting for <5% of the variance in clinical pain and physical function and <10% of variance in experimental pain.

Conclusion

The incorporation of environmental and behavioral factors reduced relationships between sociodemographic groups and pain-related outcomes. Pain sites, BMI, and income were significant predictors across multiple models. The current study adds to a body of research on the complex array of factors contributing to disparities in pain-related outcomes.

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.

Beyond challenges and enrichment: a qualitative account of cross-cultural experiences of nursing patients with an ethnic minority background in Norway

BACKGROUND

Substantial mass migrations to the Scandinavian countries have made them heterogeneous and multicultural societies. Migration has also influenced the workforce, especially the healthcare system that has had to accommodate a culturally diverse population. This qualitative study aimed to explore nurses' experiences in caring for patients with an ethnic minority background.

METHODS

Focus group interviews with a total of 21 nurses were conducted. Thematic analysis was performed on the transcribed and translated interviews.

RESULTS

The findings of this study revealed three major themes: various experiences concerning language barriers and the use of interpreters, the impact of religious and cultural values, and caring for patients with an ethnic minority background is professionally interesting but demanding.

CONCLUSIONS

Caring for culturally diverse patients offers both challenges and opportunities to enhance cultural competence and cultural sensitivity among nurses. Various culturally divergent needs of patients such as family visits, food preferences, expression of pain, and gender sensitivity are interlinked and depend on effective communication during encounters with nurses and the healthcare system at large.

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.

Short incision versus minimally invasive surgery with tool-kit for carpal tunnel syndrome release: a prospective randomized control trial to evaluate the anterior wrist pain and time to return to work or activities

Trial design

The prospective randomized controlled trial.

Background

This study compares outcomes in terms of early postoperative anterior wrist pain and time to return to work or activities of daily living of patients who underwent carpal tunnel syndrome (CTS) release with short incision and those who had minimally invasive surgery (MIS) with CTS kits.

Methods

A total of 24 patients diagnosed with primary CTS confirmed with electrodiagnosis at an academic university hospital were randomly assigned into one of two groups of 12 patients each: a short incision group and an MIS with tool-kit group using computer-generated block randomization (block of four). Sequentially numbered, opaque, sealed envelopes were used in the allocation concealment process. In the short incision group, skin was incised longitudinally from Kaplan’s line to the area distal to transverse wrist crease (2.5–4.0 cm) while in the tool-kit group, an incision of less than 2.5 cm. was made using special MIS-CTS kits. Primary outcomes evaluated include visual analogue scale (VAS) measurement of pain intensity in the anterior carpal area both while at rest and while conducting daily activities at the 2nd week postoperatively as well as the time to return to activities of daily living and work. Improvement in the Michigan hand questionnaire (MHQ) score, a secondary outcome, was also measured at the 2nd week postoperatively. Patients, allocator and outcome assessor were blinded.

Results

Demographic data, including preoperative electrodiagnostic severity and occupation, were similar in the two groups. There were no significant differences in terms of VAS of the early postoperative anterior carpal area at rest (p > 0.99), while conducting daily activities (p = 0.89) and time to return to activities of daily living (p = 0.46) and work (p = 0.24). The MHQ score improvement at the 2nd week postoperatively showed no significant difference between the groups (p = 0.95). The MIS wound length in the tool-kit group was significantly shorter than in the short incision group (1.95 vs 2.92 cm, p < 0.01).

Conclusions

There is no difference in early postoperative anterior wrist pain, time to return to work or to activities of daily living between the surgical techniques. Short incision is recommended for benefit in term of cost-effectiveness, while MIS with tool-kit could be preferred in patients who concerned in cosmetic appearance between the surgical techniques.

Trial registration

www.clinicaltrials.in.th (TCTR20200530003). Registered 30 May 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05663-5.

Skin conductance levels and responses in Asian and White participants during fear conditioning✰

Fear conditioning paradigms are frequently used in the translational study of anxiety and fear-related disorders. Accordingly, it is important to understand whether the measurement of fear conditioning responses is systematically influenced by an individual's race. Studies have found increased pain sensitivity and smaller physiological startle responses in Asian individuals, compared to White individuals; to our knowledge, no studies have evaluated whether skin conductance response (SCR) outcomes differ between Asian and White individuals. In a series of secondary data analyses, we investigated potential differences in skin conductance level (SCL), orienting SCR, unconditioned SCR, SCR to CS+ and CS-, differential SCR, and differential SCR non-responder status. In sample 1, Asian participants (n = 97) demonstrated a significantly smaller mean differential SCR compared to White participants (n = 86). No other between group differences were observed. In sample 2, there was no difference in mean differential SCR between Asian (n = 52) and White (n = 62) participants, although more Asian participants failed to show adequate skin conductance levels for study entry. To our knowledge, this is the first study to evaluate differences between Asian and White samples using skin conductance outcomes in a fear conditioning paradigm. We detected only subtle evidence for SCR differences between Asian and White samples, unlikely to reach significance outside large studies.

The Model Minority Myth, Data Aggregation, and the Role of Medical Schools in Combating Anti-Asian Sentiment

The COVID-19 pandemic has resulted in an alarming increase in hate incidents directed toward Asian Americans and Pacific Islanders (AAPIs), including verbal harassment and physical assault, spurring the nationwide #StopAsianHate movement. This rise in anti-Asian sentiment is occurring at a critical time of racial reckoning across the United States, galvanized by the Black Lives Matter movement, and of medical student calls for the implementation of antiracist medical curricula. AAPIs are stereotyped by the model minority myth, which posits that AAPIs are educated, hardworking, and therefore able to achieve high levels of success. This myth acts as a racial wedge between minorities and perpetuates harm that is pervasive throughout the field of medicine. Critically, the frequent aggregation of all AAPI subgroups as one monolithic community obfuscates socioeconomic and cultural differences across the AAPI diaspora while reinforcing the model minority myth. Here, the authors illustrate how the model minority myth and data aggregation have negatively affected the recruitment and advancement of diverse AAPI medical students, physicians, and faculty. Additionally, the authors discuss how data aggregation obscures health disparities across the AAPI diaspora and how the model minority myth influences the illness experiences of AAPI patients. Importantly, the authors outline specific actionable policies and reforms that medical schools can implement to combat anti-Asian sentiment and support the AAPI community.

Patient Race, Ethnicity, Language, and Pain Severity in Primary Care: A Retrospective Electronic Health Record Study

BACKGROUND

Patient race, ethnicity, and culture including language are intertwined and may influence patient reporting of pain severity.

PURPOSE

To describe documentation of patient's self-reported pain presence and severity by race, ethnicity, and language, specifically, Spanish, Hmong, Lao, or Khmer requiring an interpreter or English.

DESIGN AND SAMPLE

Retrospective, electronic health record clinical data mining study of 79,195 patient visits with documented pain scores from one primary care clinic.

METHODS

Hurdle regression was used to explore the effect of race, ethnicity, and language on the chances of having any pain (vs. no pain) and pain severity for visits with pain scores ≥1, controlling for age, sex, and documentation of a pain diagnosis. Mann-Whitney tests were used to explore the influence of English vs. non-English language on pain severity within a race or ethnicity category.

RESULTS

Pain scores were higher for limited English proficiency, compared with English-speaking, patients within the Asian race or Hispanic/Latino ethnicity category. Older age, female sex, pain diagnosis, Black or African American race, and Spanish or Lao language increased the chance of having any pain. These same factors, plus American Indian or Alaska Native race, contributed to higher pain severity. Asian race, in contrast, decreased the chance of reporting any pain and contributed to lesser pain severity.

CONCLUSIONS

Race, in addition to a new area of focus, language, impacted both the chances of reporting any pain and pain severity. Additional research is needed on the impact of language barriers on pain severity reporting, documentation, and differences in pain outcomes and disparities.

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.

Pain and Opioid Consumption and Mobilization after Surgery: Post Hoc Analysis of Two Randomized Trials

BACKGROUND

Early mobilization is incorporated into many enhanced recovery pathways. Inadequate analgesia or excessive opioids may restrict postoperative mobilization. The authors tested the hypotheses that in adults recovering from abdominal surgery, postoperative pain and opioid consumption are inversely related to postoperative mobilization, and that postoperative mobilization is associated with fewer potentially related complications.

METHODS

The authors conducted a subanalysis of two trials that enrolled adults recovering from abdominal surgery. Posture and movement were continuously monitored for 48 postoperative hours using noninvasive untethered monitors. Mobilization was defined as the fraction of monitored time spent sitting or standing.

RESULTS

A total of 673 patients spent a median [interquartile range] of 7% [3 to 13%] of monitored time sitting or standing. Mobilization time was 1.9 [1.0 to 3.6] h/day for patients with average pain scores 3 or lower, but only 1.2 [0.5 to 2.6] h/day in those with average scores 6 or greater. Each unit increase in average pain score was associated with a decrease in mobilization time of 0.12 (97.5% CI, 0.02 to 0.24; P = 0.009) h/day. In contrast, there was no association between postoperative opioid consumption and mobilization time. The incidence of the composite of postoperative complications was 6.0% (10 of 168) in the lower mobilization quartile, 4.2% (7 of 168) in the second quartile, and 0% among 337 patients in the highest two quartiles (P = 0.009).

CONCLUSIONS

Patients recovering from abdominal surgery spent only 7% of their time mobilized, which is considerably less than recommended. Lower pain scores are associated with increased mobility, independently of opioid consumption. Complications were more common in patients who mobilized poorly.

EDITOR’S PERSPECTIVE

Normative FJS-12 scores for the knee in an Asian population: a cross-sectional study

Background

The Forgotten Joint Score is a patient-reported outcome measure validated in assessing patients post knee arthroplasty, anterior cruciate ligament (ACL) reconstruction surgery and patellar dislocation. A previous study had established the normative scores of a population in the USA but included knees with pathology. The aim of our study is to obtain normative Forgotten Joint Scores in young Asian adults without any pre-existing knee pathologies to increase the interpretability of the Forgotten Joint Score-12 (FJS-12) score.

Methods

We conducted a cross-sectional study across young healthy Asian adults via electronic platforms. Participants who had sought either Western medical consultation, physiotherapy or traditional medical therapies were excluded. Demographic data, occupation, type of sport played, and FJS-12 scores were collected. Scores were stratified into subgroups and analysed.

Results

There were 172 participants who met our inclusion criteria for this study. The average age of participants in our study was 28.1 ± 10.5 years (range 14–70 years), with 83 (47.7%) participants falling into the ages 21–25 years. Average body mass index (BMI) was 21.9 ± 3.3 kg/m² (range 14.7–36.3 kg/m²). The average FJS-12 score was 62.8 ± 25.6. The median FJS-12 was 63.5 with a range of 4.2–100. Nine participants (5.2%) scored the maximum score possible, and 56 (32.6%) participants scored below the midpoint score of 50. The percentiles for each subgroup of participants were tabulated and reported. Notably, males aged 46–70 years old scored the highest average FJS-12 score of 73.4 ± 5.5, and females aged 31–45 years old scored the lowest FJS-12 score of 57.1 ± 25.1. Females scored lower than males, although the difference was not statistically significant (p = 0.157). There were no significant correlations between BMI, age, or type of sport played with FJS-12; however, interestingly, we observed that women reported similar FJS-12 scores across all age groups, while men reported better scores with increasing age.Interestingly, we observed that women reported similar FJS-12 scores across all age groups, while men reported better scores with increasing age. 

Conclusion

Having normative values provides opportunities for benchmarking and comparing individuals against age- and gender-matched peers in the general population. Knowledge of normative values for FJS-12 scores would aid evaluating and tracking progress in patients recovering from injuries or undergoing post-surgery rehabilitation. This would help clinicians  determine if they return to ‘normal’ post intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43019-021-00122-2.

Persistent Incisional Pain after Noncardiac Surgery: An International Prospective Cohort Study

BACKGROUND

The purpose of this study was to determine the incidence, characteristics, impact, and risk factors associated with persistent incisional pain. The hypothesis was that patient demographics and perioperative interventions are associated with persistent pain.

METHODS

This was a secondary analysis of an international prospective cohort study from 2012 to 2014. This study included patients who were 45 yr of age or older who underwent major inpatient noncardiac surgery. Data were collected perioperatively and at 1 yr after surgery to assess for the development of persistent incisional pain (pain present around incision at 1 yr after surgery).

RESULTS

Among 14,831 patients, 495 (3.3%; 95% CI, 3.1 to 3.6) reported persistent incisional pain at 1 yr, with an average pain intensity of 3.6 ± 2.5 (0 to 10 numeric rating scale), with 35% and 14% reporting moderate and severe pain intensities, respectively. More than half of patients with persistent pain reported needing analgesic medications, and 85% reported interference with daily activities (denominator = 495 in the above proportions). Risk factors for persistent pain included female sex (P = 0.007), Asian ethnicity (P < 0.001), surgery for fracture (P < 0.001), history of chronic pain (P < 0.001), coronary artery disease (P < 0.001), history of tobacco use (P = 0.048), postoperative patient-controlled analgesia (P < 0.001), postoperative continuous nerve block (P = 0.010), insulin initiation within 24 h of surgery (P < 0.001), and withholding nonsteroidal anti-inflammatory medication or cyclooxygenase-2 inhibitors on the day of surgery (P = 0.029 and P < 0.001, respectively). Older age (P < 0.001), endoscopic surgery (P = 0.005), and South Asian (P < 0.001), Native American/Australian (P = 0.004), and Latin/Hispanic ethnicities (P < 0.001) were associated with a lower risk of persistent pain.

CONCLUSIONS

Persistent incisional pain is a common complication of inpatient noncardiac surgery, occurring in approximately 1 in 30 adults. It results in significant morbidity, interferes with daily living, and is associated with persistent analgesic consumption. Certain demographics, ethnicities, and perioperative practices are associated with increased risk of persistent pain.

EDITOR’S PERSPECTIVE

Quantitative Sensory Testing Protocols to Evaluate Central and Peripheral Sensitization in Knee OA: A Scoping Review

OBJECTIVE

This scoping review analyzed various quantitative sensory testing methodologies used in the assessment of sensitization and how sensitization is defined in people with knee osteoarthritis.

DESIGN

A scoping review.

SETTING

All clinical and research settings.

SUBJECTS

Non-surgical adults with knee osteoarthritis.

METHODS

This scoping review was guided by existing scoping review methodologies. Relevant studies were extracted from the following electronic databases: Medical Literature Analysis and Retrieval System Online, Excerpta Medica Database, Allied and Complementary Medicine Database and the Cumulative Index to Nursing Allied Health Literature. Abstract and full article screening and data extraction were performed in pairs. Information on quantitative sensory testing techniques and parameters was extracted and summarized in tables. General and technique specific definitions of sensitization were extracted from included texts.

RESULTS

Our search yielded 4199 articles, of which 50 were included in our review. The most common quantitative sensory test was pressure pain threshold. In total 28 unique testing sites were found speaking to the high degree of variability between studies. Sensitization was poorly defined with only 8 studies fully operationalizing it, 22 partially, and the remainder did not provide sufficient information to meet our criteria.

CONCLUSION

This scoping review has provided an overview of the most common methods of quantitative sensory testing being implemented in the assessment of nervous system sensitization to nociceptive signaling in people with knee osteoarthritis. This study provides a foundation for future development of quantitative sensory testing methodology for research and clinical practice in the osteoarthritis population.

Baseline clinical characteristics of predicted structural and pain progressors in the IMI-APPROACH knee OA cohort

OBJECTIVES

To describe the relations between baseline clinical characteristics of the Applied Public-Private Research enabling OsteoArthritis Clinical Headway (IMI-APPROACH) participants and their predicted probabilities for knee osteoarthritis (OA) structural (S) progression and/or pain (P) progression.

METHODS

Baseline clinical characteristics of the IMI-APPROACH participants were used for this study. Radiographs were evaluated according to Kellgren and Lawrence (K&L grade) and Knee Image Digital Analysis. Knee Injury and Osteoarthritis Outcome Score (KOOS) and Numeric Rating Scale (NRS) were used to evaluate pain. Predicted progression scores for each individual were determined using machine learning models. Pearson correlation coefficients were used to evaluate correlations between scores for predicted progression and baseline characteristics. T-tests and χ² tests were used to evaluate differences between participants with high versus low progression scores.

RESULTS

Participants with high S progressions score were found to have statistically significantly less structural damage compared with participants with low S progression scores (minimum Joint Space Width, minJSW 3.56 mm vs 1.63 mm; p<0.001, K&L grade; p=0.028). Participants with high P progression scores had statistically significantly more pain compared with participants with low P progression scores (KOOS pain 51.71 vs 82.11; p<0.001, NRS pain 6.7 vs 2.4; p<0.001).

CONCLUSIONS

The baseline minJSW of the IMI-APPROACH participants contradicts the idea that the (predicted) course of knee OA follows a pattern of inertia, where patients who have progressed previously are more likely to display further progression. In contrast, for pain progressors the pattern of inertia seems valid, since participants with high P score already have more pain at baseline compared with participants with a low P score.

A randomized non-inferiority pilot study on the use of methoxyflurane (Penthrox®) for pain control in the emergency department

Background:

Patients commonly visit the emergency department for pain after musculoskeletal injury, but the problem of oligoanalgesia is prevalent. Methoxyflurane (Penthrox®) is an inhalational analgesic for moderate to severe trauma-associated pain in stable and conscious patients. It is a fast-acting, effective analgesic that can be readily administered via a non-invasive route, making it an attractive agent for managing acute pain in the emergency departments.

Objectives:

The aim was to assess the analgesic efficacy of methoxyflurane in patients with acute traumatic pain by comparing it to ketorolac, a standard analgesic treatment for moderate pain in emergency departments in Hong Kong.

Methods:

This was a single-center, open-label, randomized controlled, parallel-group, non-inferiority pilot study that enrolled adult patients with moderate trauma-associated pain in an emergency department in Hong Kong. Patients were randomized 1:1 to the methoxyflurane group or the ketorolac group. The primary outcome was the change in pain intensity measured by visual analogue scale from baseline to 5, 15, 30, and 60 min after drug administration.

Results:

Twenty patients received methoxyflurane, and twenty patients received ketorolac. There were significant reductions in pain score over 60 min in both groups. The pain reduction at 5 min was significantly greater for the methoxyflurane group (−13.912 mm; 95% confidence interval = −20.008 to −7.817) than for the ketorolac group (−4.888 mm; 95% confidence interval = −10.983 to 1.208), with the treatment effect (−9.025 mm; 95% confidence interval = −17.656 to −0.393; p = 0.041) demonstrating superiority of methoxyflurane. The treatment effect at 15 and 30 min demonstrated non-inferiority of methoxyflurane versus ketorolac.

Conclusion:

Methoxyflurane provided non-inferior analgesia in the first 30 min with a faster onset of action when compared with ketorolac in moderate traumatic pain. It can be considered a non-invasive, rapid-acting, and effective first-line alternative to currently available analgesics for traumatic pain in emergency settings.

Gender and Sex Are Key Determinants in Osteoarthritis Not Only Confounding Variables. A Systematic Review of Clinical Data

Many risk factors for osteoarthritis (OA) have been noted, while gender/sex differences have been understated. The work aimed to systematically review literature investigating as primary aim the relationship between gender/sex related discriminants and OA. The search was performed in PubMed, Science Direct and Web of Knowledge in the last 10 years. Inclusion criteria were limited to clinical studies of patients affected by OA in any joints, analyzing as primary aim gender/sex differences. Exclusion criteria were review articles, in vitro, in vivo and ex vivo studies, case series studies and papers in which gender/sex differences were adjusted as confounding variable. Of the 120 records screened, 42 studies were included. Different clinical outcomes were analyzed: morphometric differences, followed by kinematics, pain, functional outcomes after arthroplasty and health care needs of patients. Women appear to use more health care, have higher OA prevalence, clinical pain and inflammation, decreased cartilage volume, physical difficulty, and smaller joint parameters and dimensions, as compared to men. No in-depth studies or mechanistic studies analyzing biomarker differential expressions, molecular pathways and omic profiles were found that might drive preclinical and clinical research towards sex-/gender-oriented protocols.

Applying the NIA Health Disparities Research Framework to Identify Needs and Opportunities in Chronic Musculoskeletal Pain Research

Disparities in the experience of chronic musculoskeletal pain in the United States stem from a confluence of a broad array of factors. Organized within the National Institute on Aging Health Disparity Research Framework, a literature review was completed to evaluate what is known and what is needed to move chronic musculoskeletal pain research forward specific to disproportionately affected populations. Peer-reviewed studies published in English, on human adults, from 2000 to 2019, and conducted in the United States were extracted from PubMed and Web of Science. Articles were reviewed for key words that focused on underrepresented ethnic/race groups with chronic musculoskeletal pain applying health factor terms identified in the NIAHealth Disparity Research Framework four levels of analysis: 1) environmental, 2) sociocultural, 3) behavioral, and 4) biological. A total of 52 articles met inclusion criteria. There were limited publications specific to underrepresented ethnic/race groups with chronic musculoskeletal pain across all levels with particular research gaps under sociocultural and biological categories. Current limitations in evidence may be supplemented by a foundation of findings specific to the broader topic of "chronic pain" which provides guidance for future investigations. Study designs including a focus on protective factors and multiple levels of analyses would be particularly meritorious. PERSPECTIVE: Chronic musculoskeletal pain unequally burdens underrepresented ethnic/race groups. In order to move research forward and to systematically investigate the complex array of factors contributing toward health disparities, an organized approach is necessary. Applying the NIA Health Disparities Research Framework, an overview of the current state of evidence specific to chronic musculoskeletal pain and underrepresented ethnic/race groups is provided with future directions identified.

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.

Chronic postsurgical pain after total knee arthroplasty: A prospective cohort study in Japanese population

OBJECTIVES

To elucidate the prevalence and risk factors of chronic postsurgical pain (CPSP) after primary total knee arthroplasty (TKA) in Japanese population.

METHODS

Consecutive patients undergoing primary TKA in a Japanese tertiary hospital (211 knees) were assessed. CPSP after TKA was defined as moderate to severe pain (VAS >30 mm), either at rest or during walking, one year after surgery. Clinical and radiographic data were compared between CPSP and non-CPSP groups and multivariate logistic regression was used to identify predictors of CPSP.

RESULTS

The prevalence of CPSP was 8.8%. CPSP group showed significantly higher preoperative WOMAC subscales (pain, function and stiffness), higher rate of postoperative coronal malalignment (femorotibial angle >178° or <170°) and larger varus angle of tibial component compared with non-CPSP group. Logistic regression analysis revealed that preoperative higher WOMAC pain and postoperative coronal malalignment were independent risk factors of CPSP. In a subgroup analysis of patients with well-aligned TKA, preoperative pain VAS at rest was the only risk factor of CPSP.

CONCLUSION

Preoperative severe pain and postoperative coronal malalignment were independent risk factors of CPSP after TKA. Preoperative pain management in patients with severe pain and good coronal alignment after TKA possibly minimize the development of CPSP.

Changes in Experimental Pain Sensitivity from Using Home-Based Remotely Supervised Transcranial Direct Current Stimulation in Older Adults with Knee Osteoarthritis

OBJECTIVE

The present study examined the effects of home-based remotely supervised transcranial direct current stimulation on quantitative sensory testing measurements in older adults with knee osteoarthritis. Participants were hypothesized to experience improved pain measurements over time.

DESIGN

Open-label, single-arm trial.

SETTING

Southeast Texas between March and November 2018 at a nursing school and participant homes.

SUBJECTS

Older adults (aged 50-85 years) with self-reported unilateral or bilateral knee osteoarthritis pain who met eligibility criteria set by the American College of Rheumatology.

METHODS

The intervention was applied with a constant current intensity for 20 minutes every weekday for two weeks (10 total sessions). Quantitative measures of pain were collected three times over 10 days (days 1, 5, and 10) and included heat threshold and tolerance, pressure pain threshold, punctate mechanical pain, pain, and conditioned pain modulation. Analyses used nonparametric tests to evaluate differences between day 1 and day 10. Generalized linear mixed models were then used to evaluate change across all three time points for each measure. Bayesian inference was used to provide the posterior probability of longitudinal effects.

RESULTS

Nonparametric tests found improvements in seven measures, and longitudinal models supported improvements in 10 measures, with some nonlinear effects.

CONCLUSIONS

The home-based, remotely supervised intervention improved quantitative measurements of pain in older adults with knee osteoarthritis. This study contributes to the growing body of literature supporting home-based noninvasive stimulation interventions.

Racial/Ethnic, Socioeconomic, and Geographic Disparities in the Epidemiology of Knee and Hip Osteoarthritis

It is estimated that 32.5 million US adults have clinical osteoarthritis (OA), with the most common sites being knee and hip. OA is associated with substantial individual and societal costs. Race/ethnicity, socioeconomic status (SES), and geographic variations in the prevalence of knee and hip OA are well established around the world. In addition, clinical outcomes associated with hip and knee OA differ according to race/ethnicity, SES, and geography. This variation is likely multifactorial and may also reflect country-specific differences in health care systems. The interplay between different factors, such as geography, SES, and race/ethnicity, is difficult to study.

Relationship between Acculturative Stress and Pain Catastrophizing in Korean Americans

Acculturative stress is speculated to be a sociocultural factor contributing to pain since cultural beliefs and practices can influence the way patients perceive and respond to pain. However, the relationship between acculturative stress and pain catastrophizing remains poorly understood. Therefore, we examined the relationship between acculturative stress and pain catastrophizing in Korean Americans. We collected survey data from Korean American in Texas (N = 374). Acculturative stress was measured with the Acculturative Stress Scale, and pain catastrophizing was measured with the Pain Catastrophizing Scale. Participants' mean age was 46.89 years, and 63% were women. Bivariate and multivariate statistical analyses indicated that higher acculturative stress may contribute to higher pain catastrophizing (regression coefficient = 1.02, P = 0.04). These findings advance our understanding of sociocultural factors associated with pain in Korean Americans; additional research with a larger sample is warranted for cross-validation.

Placebo hypoalgesia: racial differences

No large-cohort studies that examine potential racial effects on placebo hypoalgesic effects exist. To fill this void, we studied placebo effects in healthy and chronic pain participants self-identified as either African American/black (AA/black) or white. We enrolled 372 study participants, 186 with a diagnosis of temporomandibular disorder (TMD) and 186 race-, sex-, and age-matched healthy participants to participate in a placebo experiment. Using a well-established paradigm of classical conditioning with verbal suggestions, each individual pain sensitivity was measured to calibrate the temperatures for high- and low-pain stimuli in the conditioning protocol. These 2 temperatures were then paired with a red and green screen, respectively, and participants were told that the analgesic intervention would activate during the green screens to reduce pain. Participants then rated the painfulness of each stimulus on a visual analog scale ranging from 0 to 100. Racial influences were tested on conditioning strength, reinforced expectations, and placebo hypoalgesia. We found that white participants reported greater conditioning effects, reinforced relief expectations, and placebo effects when compared with their AA/black counterparts. Racial effects on placebo were observed in TMD, although negligible, short-lasting, and mediated by conditioning strength. Secondary analyses on the effect of experimenter-participant race and sex concordance indicated that same experimenter-participant race induced greater placebo hypoalgesia in TMDs while different sex induced greater placebo hypoalgesia in healthy participants. This is the first and largest study to analyze racial effects on placebo hypoalgesia and has implications for both clinical research and treatment outcomes.

The roles of race, sex and cognitions in response to experimental pain

BACKGROUND

This study reports a multivariate test of sex and race differences in experimental pain, and the degree to which these differences could be uniquely attributable to three levels of cognition: primary appraisals (threat, challenge), secondary appraisals (pain catastrophizing) and/or cognitive processes (mindful observing, non-reactivity). Both the predictive and mediator role of the cognitive variables was of interest.

METHODS

The study employed a cross-sectional experimental design, with the cold pressor task employed as the pain stimulus. The total sample included N = 355 healthy adults (67% female, 33% male; 70% Caucasian, 30% Asian).

RESULTS

Significant sex and race differences on pain tolerance were found, with females and racial minorities reporting less pain tolerance (ps < 0.001). Males reported significantly higher challenge appraisals and non-reactivity, and lower pain catastrophizing than females; Asians reported significantly higher threat appraisals and pain catastrophizing than Caucasians. In multivariate analyses, challenge appraisals and non-reactivity emerged as the strongest predictors of pain tolerance. Furthermore, challenge appraisals mediated the sex-pain tolerance association (p = .017).

CONCLUSIONS

This study showed that race and sex differences, at least in part, may be accounted for by differences in pain-related cognitions.

SIGNIFICANCE

The three levels of cognition investigated in this research represent changeable, important processes for potentially mitigating the impact of pain in vulnerable groups.

A Biopsychosocial Model of Chronic Pain for Older Adults

Population

Comprehensive evaluation of chronic pain in older adults is multifaceted.

Objective and Methods

Research on chronic pain in older adults needs to be guided by sound conceptual models. The purpose of this paper is to describe an adaptation of the Biopsychosocial Model (BPS) of Chronic Pain for older adults. The extant literature was reviewed, and selected research findings that provide the empiric foundation for this adaptation of the BPS model of chronic pain are summarized. The paper concludes with a discussion of specific recommendations for how this adapted model can be used to guide future research.

Conclusions

This adaptation of the BPS model of chronic pain for older adults provides a comprehensive framework to guide future research in this vulnerable population.

Mirogabalin for the management of postherpetic neuralgia: a randomized, double-blind, placebo-controlled phase 3 study in Asian patients

Mirogabalin has demonstrated a well-balanced profile of efficacy and safety and may provide an alternative therapeutic option for the treatment of postherpetic neuralgia.

This study investigated the safety and efficacy of mirogabalin, a novel, potent, selective ligand of the α₂δ subunit of voltage-dependent Ca²⁺ channels, for the treatment of postherpetic neuralgia (PHN). In this multicenter, double-blind, placebo-controlled phase 3 study, Asian patients ≥20 years with PHN were randomized 2:1:1:1 to placebo or mirogabalin 15, 20, or 30 mg/day for up to 14 weeks (NCT02318719). The primary efficacy endpoint was the change from baseline in average daily pain score at week 14, defined as a weekly average of daily pain (0 = “no pain” to 10 = “worst possible pain,” for the last 24 hours). Of 765 patients randomized, 763 received ≥ 1 dose of the study drug and were included in the analysis; 303, 152, 153, and 155 received placebo, mirogabalin 15, 20, or 30 mg/day, respectively. A total of 671 (87.7%) patients completed the study. At week 14, the difference in average daily pain score least squares mean vs placebo was −0.41, −0.47, and −0.77, respectively; all mirogabalin groups showed statistical significance. The most common treatment-emergent adverse events were somnolence, nasopharyngitis, dizziness, weight increase, and edema, and all of them were mild or moderate in severity. Mirogabalin was superior to placebo in all groups for relieving PHN and appeared well tolerated.

Over-triage occurs when considering the patient's pain in Korean Triage and Acuity Scale (KTAS)

Background

The Korean Triage and Acuity Scale (KTAS) was developed based on the Canadian Emergency Department Triage and Acuity Scale. In patients with pain, to determine the KTAS level, the pain scale is considered; however, since the degree of pain is subjective, this may affect the accuracy of KTAS. The purpose of this study was to evaluate the accuracy of KTAS in predicting patient's severity with the degree of pain used as a modifier.

Method

A retrospective observational cohort study was conducted in an urban tertiary hospital emergency department (ED). We investigated patients over 16 years old from January to June 2016. The patients were divided into the pain and non-pain groups according to whether the degree of pain was used as a modifier or not. We compared the predictive power of KTAS on the urgency of patients between the two groups. Acute area registration in the ED, emergency procedure, emergency operation, hospitalization, intensive care unit admission, and 7-day mortality were used as markers to determine urgent patients.

Results

Overall, 24,253 patients were included in the study, with 9,175 (37.8%) in the pain group. The proportions of patients with KTAS 1–3 were 61.4% in the pain and 75.6% in the non-pain groups. Among patients with KTAS 2–3, the proportion of urgent patients was higher in the non-pain group than the pain group (p<0.001). The odds ratios for urgent patients at each KTAS level revealed a more evident discriminatory power of KTAS for urgent patients in the non-pain group. The predictability of KTAS for urgent patients was higher in the non-pain group than the pain group (area under the curve; 0.736 vs. 0.765, p-value <0.001).

Conclusions

Considering the degree of pain with KTAS led to overestimation of patient severity and had a negative impact on the predictability of KTAS for urgent patients.

Racial and ethnic differences in the experience and treatment of noncancer pain

The burden of pain is unequal across racial and ethnic groups. In addition to racial and ethnic differences in the experience of pain, there are racial and ethnic disparities in the assessment and treatment of pain. In this article, we provide a nonexhaustive review of the biopsychosocial mechanistic factors contributing to racial and ethnic differences in both the experience and treatment of pain. Using a modified version of the Socioecological Model, we focus on patient-, provider- and system-level factors including coping, perceived bias and discrimination, patient preferences, expectations, patient/provider communication, treatment outcomes and healthcare access. In conclusion, we provide psychosocial factors influencing racial and ethnic differences in pain and highlight future research targets and possible solutions to reduce these disparities.

The Relationship between Acculturation and Experimental Pain Sensitivity in Asian Americans with Knee Osteoarthritis

Multiple studies in healthy populations and clinical samples have shown that ethnic minorities have greater pain sensitivity than their majority counterparts. Acculturation is speculated to be one of the sociocultural factors contributing to pain sensitivity since cultural beliefs and practices can influence the way patients perceive and respond to pain. However, the relationship of acculturation to pain sensitivity in minority populations remains poorly understood. Therefore, in this cross-sectional study, we examined the relationship between acculturation and experimental pain sensitivity in 50 Asian Americans residing in North Central Florida with knee osteoarthritis pain. The Suinn-Lew Asian Self Identity Acculturation Scale was used to assess acculturation, and multimodal quantitative sensory testing was performed to measure experimental sensitivity, including heat pain tolerance, pressure pain threshold, and punctate mechanical pain. Descriptive and regression analyses were performed. Participants' mean age was 55.7 years, and about half of this sample were Korean American (56%). The participants had lived in the United States for 21 years on average. Regression analyses indicated that lower acculturation to American culture may contribute to greater experimental pain sensitivity. Asian Americans who were more acculturated to the American culture had higher heat pain tolerance (beta = 0.61, P=0.01), higher pressure pain threshold (beta = 0.59, P=0.02), and lower ratings of punctate mechanical pain (beta = -0.70, P < 0.01). These findings add to the literature regarding sociocultural factors associated with pain in Asian Americans; additional research with a larger and more diverse sample of Asian Americans is warranted for cross-validation.

Evaluating psychosocial contributions to chronic pain outcomes

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

The perception of procedural vascular laser pain and discrepancies amongst patients, physicians, and industry

BACKGROUND

The inherent subjectivity of pain perception makes pre-procedural pain counseling especially challenging. Setting the wrong pain expectations will negatively impact the patient's experience and affect their physiologic and emotional state. Best practices for sourcing pain related information about a given procedure, however, remains understudied. This retrospective study explores the accuracy of industry materials for describing procedural pain in a clinical trial when compared to subject reported pain scores from the same clinical trial.

METHODS

Median and mode pain scores were collected from the data of a past clinical trial investigating a dual wavelength laser used for 4 different types of treatments. Industry provided materials were reviewed to ascertain language regarding procedural pain. The principal investigator was interviewed about setting pain expectations during the trial. Subject-reported pain scores and verbal pain descriptors were transferred to validated pain scales, the Numerical Rating Scale and the Verbal Rating Scale, for comparison.

RESULTS

A total of 85 procedural pain scores were collected from 22 subject charts. The average procedural pain scores for 3 of 4 treatment types reported by subjects were translated to entirely different verbal and numerical categories of pain than that described by industry materials.

CONCLUSIONS

Industry materials failed to capture the range of procedural pain scores reported by subjects for 3 of 4 treatment types in a clinical trial setting. When counseling patients on procedural pain, physicians should take extra care to not mislead patients and cause undue physiological or emotional stress.

Prevalence of chronic postsurgical pain after thoracotomy and total knee arthroplasty: a retrospective multicenter study in Japan (Japanese Study Group of Subacute Postoperative Pain)

We performed a multicenter observational study to assess the prevalence and risk factors of persistent pain after lung cancer surgery and total knee arthroplasty (TKA) in the Japanese population. After receiving Ethics Committee approval, a retrospective chart review was performed for patients who underwent surgery at seven university hospitals in Japan in 2013. A total of 511 patients who underwent lung cancer surgery and 298 patients who underwent TKA were included. The prevalence of chronic postsurgical pain (CPSP) at 3 and 6 months was 18 and 12% after lung surgery and 49 and 33% after TKA, respectively. The prevalence of analgesic use at 3 and 6 months was 16 and 9% after lung surgery and 34 and 22% after TKA, respectively. In both groups, preoperative analgesic use was associated with CPSP. Anesthetic methods or techniques during both types of surgery did not significantly affect the prevalence of CPSP. This is the first study in which the prevalence of CPSP after lung surgery and TKA in Japanese population was extensively evaluated in a multicenter trial. Further prospective studies are needed to confirm the prevalence of CPSP in the Japanese population and to identify risk factors and prevention methods.

Test Procedures to Assess Somatosensory Abnormalities in Individuals with Peripheral Joint Pain: A Systematic Review of Psychometric Properties

BACKGROUND

Test procedures that were developed to assess somatosensory abnormalities should possess optimal psychometric properties (PMPs) to be used in clinical practice. The aim of this systematic review was to evaluate the literature to assess the level of evidence for PMPs of test procedures investigated in individuals with peripheral joint pain (PJP).

METHODS

A comprehensive electronic literature search was conducted in 7 databases from inception to March 2016. The Quality Appraisal for Reliability Studies (QAREL) checklist and the Consensus-based Standards for the Selection of Health Status Measurement Instruments (COSMIN) tool were used to assess risk for bias of the included studies. Level of evidence was evaluated based on the methodological quality and the quality of the measurement properties.

RESULTS

Forty-one studies related to PJP were included. The majority of included studies were considered to be of insufficient methodological quality, and the level of evidence for PMPs varied across different test procedures. The level of evidence for PMPs varied across different test procedures in different types of PJP. Hand-held pressure algometry is the only test procedure that showed moderate positive evidence of intrarater reliability, agreement, and responsiveness, simultaneously, when it was investigated in patients with chronic knee osteoarthritis.

CONCLUSIONS

This systematic review identified that the level of evidence for PMPs varied across different testing procedures to assess somatosensory abnormalities for different PJP populations. Further research with standardized protocols is recommended to further investigate the predictive ability and responsiveness of reported test procedures in order to warrant their extended utility in clinical practice.

Characteristics of Chronic Pain Patients Attending a Primary Health Care Center in Oman

Objectives

To determine the characteristics of patients presenting with chronic pain in a primary health care setting in Oman.

Methods

A retrospective cross-sectional study was carried out including all patients aged ≥ 18 years who attended Sultan Qaboos University Health Center during 2010. Patients were identified to have chronic pain if they were prescribed an analgesic medication for at least three months. Patients were compared to a control group which consisted of age- and gender-matched patients with no chronic pain.

Results

Out of 6 609 patients, 241 (3.6%) were found to have chronic pain. The mean age of patients with chronic pain was 54.0±13.0 years. The majority of patients were female (n = 174; 72.1%), and most were Omani (n = 201; 83.4%). The prevalence of chronic pain was found to be significantly higher among females compared to males (4.5% vs. 2.5%; p < 0.001) and also among Omani nationals to non-nationals (83.4% vs. 70.1%; p < 0.001). Chronic pain was significantly associated with the following comorbidities; diabetes (33.1% vs. 20.7%; p < 0.001), obesity (35.2% vs. 26.5%; p = 0.001), and hypertension (51.0% vs. 38.5%; p = 0.002). Osteoarthritis was the most common pain condition (n = 104; 43.1%). Diclofenac was the most commonly prescribed drug (n = 168; 69.7%).

Conclusions

The findings of our study point towards a higher prevalence of chronic pain in Omani females. These patients were also found to have a higher prevalence of other common comorbid conditions.

Depression and Pain in Asian and White Americans With Knee Osteoarthritis

Few studies have examined the underlying psychosocial mechanisms of pain in Asian Americans. Using the biopsychosocial model, we sought to determine whether variations in depression contribute to racial group differences in symptomatic knee osteoarthritis pain between Asian Americans and non-Hispanic white Americans. The sample consisted of 100 participants, including 50 Asian Americans (28 Korean Americans, 9 Chinese Americans, 7 Japanese Americans, 5 Filipino Americans, and 1 Indian American) and 50 age- and sex-matched non-Hispanic white Americans with symptomatic knee osteoarthritis pain. The Centers for Epidemiologic Studies Depression Scale was used to assess symptoms of depression, and the Western Ontario and McMaster Universities Osteoarthritis Index and the Graded Chronic Pain Scale were used to measure clinical pain. In addition, quantitative sensory testing was used to measure experimental sensitivity to heat- and mechanically-induced pain. The results indicated that higher levels of depression in Asian Americans may contribute to greater clinical pain and experimental pain sensitivity. These findings add to the growing literature regarding ethnic and racial differences in pain and its associated psychological conditions, and additional research is warranted to strengthen these findings.

PERSPECTIVE

This article shows the contribution of depression to clinical pain and experimental pain sensitivity in Asian Americans with knee osteoarthritis. Our results suggest that Asian Americans have higher levels of depressive symptoms and that depression plays a relevant role in greater clinical pain and experimental pain sensitivity in Asian Americans.

Different pain responses to chronic and acute pain in various ethnic/racial groups

AIM

Our goal in this study was to review the similarities and differences among ethnic groups and their respective responses to acute and chronic clinically related and experimentally induced pain.

METHOD

In this review, the PUBMED and Google-Scholar databases were searched to analyze articles that have assessed the variations in both acute and chronic pain responses among different ethnic/racial groups.

RESULTS

According to the results from 42 reviewed articles, significant differences exist among ethnic-racial groups for pain prevalence as well as responses to acute and chronic pain. Compared with Caucasians, other ethnic groups are more susceptible to acute pain responses to nociceptive stimulation and to the development of long-term chronic pain.

CONCLUSION

These differences need to be addressed and assessed more extensively in the future in order to minimize the pain management disparities among various ethnic-racial groups and also to improve the relationship between pain management providers and their patients.