The IASP classification of chronic pain for ICD-11: chronic primary pain

The prevalence of chronic pain and its impact on activities of daily living disability and depressive symptoms according to multiple definitions in a Japanese population: the Hisayama study

Objectives

This study aimed to compare the prevalence of chronic pain using various definitions from previous studies and to determine the optimal definition for detecting chronic pain associated with physical and emotional dysfunction in a general Japanese population.

Methods

A total of 2700 community-dwelling Japanese residents aged ≥40 years were assessed for chronic pain and its components of duration, frequency, and intensity. The activities of daily living (ADL) disability and depressive symptoms of participants were also evaluated using the modified Lankin Scale and Patient Health Questionnaire-9. The odds ratios and the population attributable fractions (PAFs) for ADL disability and depressive symptoms were estimated using a logistic regression model.

Results

The prevalence of chronic pain varied greatly by definition, ranging from 13% for pain defined as pain duration ≥3 months, pain frequency ≥ twice a week, and pain intensity of ≥50 mm by a visual analogue scale (VAS) to 48% for a simple definition of pain duration ≥3 months. The PAFs for ADL disability and depressive symptoms were relatively high at 33% in participants with pain duration of ≥6 months and 30% in those with pain frequency of ≥twice a week, while the VAS ≥50 mm group had a low PAF of 12%.

Conclusion

For screening people with chronic pain and ADL disability or depressive symptoms, the criteria of pain duration and pain frequency yielded essentially identical results, while the criterion of pain intensity risked overlooking individuals with chronic pain and these associated symptoms.

Understanding the individual's transition from acute to chronic disabling pain: Opportunities for improved care

When acute pain persists, it is said to become chronic after 3 months. Considerable interest has focused on why acute pain appears to transition to chronic pain in some cases, but not all, especially when it becomes disabling. We examine our current understanding of the processes involved in the progression from an acute injury to disabling chronic pain. Rather than viewing this progression as a time dependent transition with specific static risk factors, we consider whether it might be more helpful to understand this evolution in terms of unique individual pathways. While brief self-report screening questionnaires assessing risk factors may enable us to stratify patients into risk levels, they do not provide information on the unique context and factors contributing to the disabling pain for each person. It is proposed that a 2-step process combining screening and individual assessment of those at high risk will enhance the prospect of both early identification and individually relevant interventions before more lasting changes emerge. Rather than being concerned with arbitrary time limits, it is argued that by aiming to understand the unique developmental pathway for those individuals identified as high risk, early, preventive interventions will be both viable and effective. Even so, there are barriers to the implementation of early assessment and matched treatments, and these remain a challenge for future research.

Evaluating amitriptyline's role in chronic TMD management: a placebo-controlled trial

BACKGROUND

To assess the effectiveness of low-dose amitriptyline in reducing pain and improving oral health-related quality of life in individuals with chronic temporomandibular disorders (TMD) over a 2-month period, compared to placebo.

METHODS

Forty participants were randomly assigned to receive either 25 mg of amitriptyline or a placebo pill for 2 months. The primary outcome was pain intensity, measured using a visual analogue scale (VAS). The secondary outcome was the impact of pain on oral health-related quality of life, assessed by the Oral Health Impact Profile questionnaire (OHIP-14). Evaluations were conducted at baseline and after the 1st and 2nd months of treatment.

RESULTS

No statistically significant differences were observed between the treatment groups at baseline (p > 0.05). After 2 months of treatment participants in amitriptyline group experienced a significantly greater reduction in spontaneous pain, with a 63.3% decrease in VAS scores. Participants in placebo group showed a much smaller reduction in spontaneous pain, with only a 16.2% decrease in VAS scores. Additionally, the amitriptyline group demonstrated a significant improvement in OHIP-14 scores (p < 0.001), whereas the placebo group showed no significant change in oral health-related quality of life (p = 0.184).

CONCLUSION

This study highlights low-dose amitriptyline as an effective treatment for chronic TMD, showing significant pain reduction and improved quality of life, underscoring its value in a multimodal approach despite the need for further research to personalize care.

TRIAL REGISTRATION

This study was registered retrospectively in ISRCTNregistry under the number ISRCTN17622685, on 01/10/2024.

Prevalence of Depression and Anxiety Among Adults With Chronic Pain: A Systematic Review and Meta-Analysis

Importance

Depression and anxiety are common among adults with chronic pain, but their prevalence is unclear.

Objectives

To evaluate the prevalence of depression and anxiety among adults with chronic pain and identify factors that moderate prevalence.

Data Sources

A literature search was conducted of MEDLINE, Embase, PsycINFO, and Cochrane Library from January 2013 to October 2023.

Study Selection

Studies reporting the prevalence of depression or anxiety using a validated assessment tool among adults with chronic pain (excluding chronic headache disorders).

Data Extraction and Synthesis

A total of 31 159 initial records were identified, and 5177 full texts were screened. Data were extracted per the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline using Covidence. Two independent reviewers completed abstract screening, full-text review, and data extraction and rated risk of bias. Random-effects meta-analyses were applied to pool prevalence, assess moderation, and compare prevalence of depression or anxiety among samples with chronic pain vs control samples.

Main Outcomes and Measures

Prevalence of depression and anxiety based on clinically significant symptoms or diagnosis. The moderators of prevalence identified were pain condition, recruitment setting, continent, age, percentage female, and pain duration.

Results

The search identified 376 studies from 50 countries comprising 347 468 individuals (mean [SD] age, 51.3 [9.5] years; 70.0% female) with chronic pain. Among adults with chronic pain, clinical symptoms of depression were present in 39.3% (95% CI, 37.3%-41.1%; I2 = 98.9%), and clinical symptoms of anxiety were present in 40.2% (95% CI, 38.0%-42.4%; I2 = 99.0%). Prevalence differed by pain condition (highest among samples of people with fibromyalgia [depression, 54.0% (95% CI, 48.5%-59.4%); anxiety, 55.5% (95% CI, 50.4%-60.4%)]; lowest among samples of people with arthritis conditions [eg, osteoarthritis: depression, 29.1% (95% CI, 20.3%-39.7%); anxiety, 17.5% (95% CI, 6.6%-38.8%)]) and was highest among younger people (depression, β = -0.02 [95% CI, -0.03 to -0.01]; anxiety, β = -0.02 [95% CI, -0.03 to -0.01]) and women (depression, β = 0.69 [95% CI, 0.31-1.08]; anxiety, β = 0.90 [95% CI, 0.48-1.33]). With regard to diagnoses, 36.7% (95% CI, 29.0%-45.1%) had a major depressive disorder, and 16.7% (95% CI, 11.8%-23.2%) had generalized anxiety disorder. Women, younger people, and people with nociplastic pain (ie, pain arising from altered nociception without tissue damage) were most likely to have depression and anxiety.

Conclusions and Relevance

In this systematic review and meta-analysis of depression and anxiety among individuals with chronic pain, approximately 40% of adults had clinically significant depression and anxiety. Women, younger people, and people with nociplastic pain were most likely to have depression and anxiety. The co-occurrence of chronic pain with depression and anxiety is a significant public health concern necessitating routine screening in clinical settings, equitable access to specialty care, and innovative treatment development.

How does chronic psychosocial distress induce pain? Focus on neuroinflammation and neuroplasticity changes

Chronic primary pain including fibromyalgia for the musculoskeletal system persists for more than 3 months. Its etiological factors and the pathophysiological mechanisms are not known, and therefore, there is no satisfactory therapy, it is an unmet medical need condition. The only etiological and aggravating factor is chronic psychosocial distress, which is known to cause neuroimmune and endocrine changes both in the periphery and the central nervous system. In this short review, we introduce our research perspective by summarizing the recent literature on the interactions between chronic pain, stress, and commonly co-morbid mood disorders. Immune activation, autoimmunity, neuro-immune-vascular crosstalks and neuroinflammation play roles in the pathophysiology of these conditions. Data on stress-induced neuroplasticity changes at cellular and molecular levels were also collected in relation to chronic primary pain both from clinical studies and animal experiments of translational relevance. Understanding these mechanisms could help to identify novel therapeutic targets for chronic primary pain including fibromyalgia.

Refining chronic pain phenotypes: A comparative analysis of sociodemographic and disease-related determinants using electronic health records

The use of electronic health records (EHR) for chronic pain phenotyping has gained significant attention in recent years, with various algorithms being developed to enhance accuracy. Structured data fields (e.g., pain intensity, treatment modalities, diagnosis codes, and interventions) offer standardized templates for capturing specific chronic pain phenotypes. This study aims to determine which chronic pain case definitions derived from structured data elements achieve the best accuracy, and how these validation metrics vary by sociodemographic and disease-related factors. We used EHR data from 802 randomly selected adults with autoimmune rheumatic diseases seen at a large academic center in 2019. We extracted structured data elements to derive multiple phenotyping algorithms. We confirmed chronic pain case definitions via manual chart review of clinical notes, and assessed the performance of derived algorithms, e.g., sensitivity/recall, specificity, positive predictive value (PPV). The highest sensitivity (67%) was observed when using ICD codes alone, while specificity peaked at 96% with a quadrimodal algorithm combining pain scores, ICD codes, prescriptions, and interventions. Specificity was generally higher in males and younger patients, particularly those aged 18-40 years, and highest among Asian/Pacific Islander and privately insured patients. PPV was highest among patients who were female, younger, or privately insured. PPV and sensitivity were lowest among males, Asian/Pacific Islander, and older patients. Variability of phenotyping results underscores the importance of refining chronic pain phenotyping algorithms within EHRs to enhance their accuracy and applicability. While our current algorithms provide valuable insights, enhancement is needed to ensure more reliable chronic pain identification across diverse patient populations. PERSPECTIVE: This study evaluates chronic pain phenotyping algorithms using electronic health records, highlighting variability in performance across sociodemographic and disease-related factors.

The medico-legal pertinence of musculoskeletal nociplastic pain

Pain conditions can be challenging; nociplastic pain, defined as pain that cannot be sufficiently explained by structural/anatomical changes, is newly categorised as the third pain mechanism. Nociplastic pain complaints are subjective, often accompanied by symptoms of fatigue, sleep and mood disturbance and cognitive difficulties with no diagnostic biomarker or reliable measurement of severity. Medico-legal challenges include attribution of causation after an alleged triggering event, assessment of severity, and reported functional impairment. This review considers nociplastic pain in regard to the musculoskeletal system with focus on causation and temporality of the pain condition and impairment. We hope that this overview will provide a better understanding of these challenging pain conditions.

Chronic pain: a modifiable target to reduce perioperative cardiovascular morbidity

Recent epidemiological studies suggest that chronic pain is a clinically under-recognised cause for cardiovascular morbidity and mortality. Up to 30% of patients undergoing surgery report chronic pain, but the impact of pre-existing pain on postoperative cardiovascular outcomes is not known. Chronic pain and cardiovascular dysfunction share fundamental pathological mechanisms. Chronic pain is a modifiable risk factor for perioperative cardiovascular morbidity.

Chronic pain in multiple sites is associated with depressive symptoms in US adults: A cross-sectional study

BACKGROUND

Chronic pain poses a significant public health challenge, yet its manifestation in multiple body areas remains insufficiently studied. This study seeks to explore the relationship between chronic pain affecting multiple sites and depression.

METHODS

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 2009 to 2010 regarding chronic pain and depression, employing weighted univariate and multivariate logistic regression analyses to explore the relationship between the number of body sites impacted by chronic pain and depression rates. Furthermore, subgroup analyses were performed to identify possible confounding factors that could affect this relationship.

RESULTS

There is a correlation between chronic pain and higher risk of depression (OR 3.821, 95% CI 3.138-4.646, P < 0.001). The multivariable-adjusted observational study indicates that, compared to individuals without chronic pain, the risk of depression is significantly associated with an increasing number of body sites affected by chronic pain. Specifically, when a person experiences chronic pain in five different areas, the risk of depression peaks (OR 16.050, 95% CI 8.723-29.905, P < 0.001).

CONCLUSION

The findings of this study indicate a significant correlation between chronic pain in multiple sites and depressive symptoms.

Inequities time-to-follow-up care and administrative action after low back pain diagnosis in active duty service members

ABSTRACT

As healthcare systems adopt data-driven methods to determine resource allocation for treating low back pain (LBP), it is critical to evaluate equity in time-to-follow-up care after an index visit and long-term occupational outcomes. This retrospective observational study included medical records of 525,252 active duty US service members who received an LBP index diagnosis from June 2016 to February 2022. Poisson generalized additive models evaluated time-to-LBP follow-up visit (primary outcome) and administrative action receipt (eg, disability evaluation; secondary outcome). Service members assigned female in the medical record compared to service members assigned male had lower cumulative hazards of follow-up visit at 1-week, but higher hazards by 4 weeks. Asian and Pacific Islander, Black, and Latino service members compared to white service members had lower cumulative hazards of follow-up visit during the acute/subacute period (up to 7, 19, 31, weeks, respectively), then higher cumulative hazards. Service members whose race and ethnicity was recorded as Other had lower hazards across time. Service members assigned female in the medical record compared to service members assigned male had lower cumulative hazards of administrative action receipt, as did Asian and Pacific Islander, Black, and Latino service members and service members whose race and ethnicity was recorded as Other compared to white service members. Overall, inequities in LBP follow-up visit timing warrant system-level programming to mitigate healthcare barriers acutely and subacutely after an LBP index visit, as well as system-level evaluation of pathways to administration action receipt.

A systematic review of social functioning and peer relationships in adolescents with chronic pain

OBJECTIVE

There is a need for a systematic review on social functioning and peer relationships among adolescents with chronic pain (ACP) given the high prevalence of chronic pain in adolescence and integral role of peer relationships in adolescent development. This review aims to examine the methods used to evaluate social functioning, the types and extent of peer relationship difficulties, and pain characteristics and sociodemographic factors related to social functioning in ACP.

METHODS

A systematic literature search of PubMed, PsycINFO, CINAHL, Web of Science, and Cochrane databases was performed. Included studies were written in English, presented original, quantitative, peer-reviewed research, had a primary focus on social functioning or peer relationships in ACP, and included study participants between the ages of 10 and 18 years. The review was registered in PROSPERO (No. CRD42022364870).

RESULTS

Twenty-eight articles were included in the review. All studies used self-, parent-, or peer-report questionnaires to evaluate social functioning. Most (89%) of the studies were cross-sectional. Findings suggest that ACP experience social difficulties frequently characterized by loneliness, social anxiety, withdrawal, and peer victimization. Studies examining the associations between social functioning and sociodemographic variables, pain location, and pain-related characteristics yielded mixed findings. Study quality was mixed, with 57.14% rated as "good."

CONCLUSIONS

Findings from this review emphasize the increased risk of reduced social connectedness and the complexity of underlying mechanisms associated with poorer social functioning among ACP. Additional research utilizing longitudinal methodologies is needed to understand potential moderators and directionality of associations between chronic pain and social functioning.

Efficacy of a home-based stretching programme on fibromyalgia symptoms: study protocol for a randomised controlled trial

BACKGROUND

This protocol was developed to describe the design of a randomised controlled trial that will examine the clinical efficacy of a 6-week, novel, home-based stretching programme compared with usual care on the effect of symptoms experienced by patients with fibromyalgia. The hypothesis is that the total score of the Fibromyalgia Impact Questionnaire (FIQ-R) and other fibromyalgia symptoms will improve 6 weeks following the stretching intervention compared with usual care.

METHODS

Fifty-eight adults under 65 years of age diagnosed with fibromyalgia will be recruited for this study. Participants will be randomised into an intervention group and a control group (waitlist). Randomisation will be stratified by sex. The intervention group will perform 6 weeks of daily stretching exercises for 6 min-a day. The control group will maintain usual care. A mHealth app will support stretching adherence. The primary outcome will be the total score of the Revised Fibromyalgia Impact Questionnaire (FIQ-R). The secondary outcomes include regional and widespread pain sensitivity, range of motion, quality of life (SF-36), mental and physical functioning and adherence. Evaluations will be performed at baseline, following 6 weeks of daily stretches (primary endpoint) and 6 months after the termination of the intervention period (secondary endpoint).

DISCUSSION

By investigating the clinical efficacy of a 6-week, novel, home-based stretching programme, we hope to provide applicable and generalisable knowledge about the efficacy of stretching exercises that can potentially help ease the burden of symptoms experienced by patients with fibromyalgia.

TRIAL REGISTRATION

NTC, NCT06487741. Registered on 24 June 2024.

Widespread pain phenotypes impact treatment efficacy results in randomized clinical trials for interstitial cystitis/bladder pain syndrome: a Multidisciplinary Approach to the Study of Chronic Pelvic Pain network study

ABSTRACT

Pain clinical trials are notoriously complex and often inefficient in demonstrating efficacy, even for known efficacious treatments. A major issue is the difficulty in the a priori identification of specific phenotypes to include in the study population. Recent work has identified the extent of widespread pain as an important determinant of the likelihood of response to therapy, but it has not been tested in clinical trials for the treatment of interstitial cystitis/bladder pain syndrome (IC/BPS). We explored this hypothesis using data from 3 previously published trials testing treatments for IC/BPS, which suggested modest benefits but did not meet a priori primary outcome statistical significance criteria. Importantly, these studies also collected symptom questionnaire data that allowed us to retrospectively identify participants with and without widespread pain. Analyzing the treatment by the degree of widespread pain revealed a difference in outcome and statistical significance level for each trial. Participants with predominately local pain (ie, limited widespread pain symptoms) responded to therapy targeting local symptoms, whereas those with widespread pain did not. Alternatively, participants with widespread pain beyond their local pelvic pain responded to more centrally acting treatments. Our results suggest that differentiating patients based on widespread vs more localized pain is a key consideration for designing future clinical trials for conditions with variable pain profiles, such as IC/BPS and potentially other pain-based syndromic disorders.

Bio-sociological and clinical factors of chronic pain and pain interference in patients undergoing hemodialysis: a cross-sectional study

BACKGROUND

End-stage kidney disease is an irreversible and incurable alteration of kidney function, requiring renal replacement therapy such as hemodialysis. Hemodialysis patients are one of the most symptomatic of all chronic kidney disease groups, including chronic pain. Overlooked, underestimated, and undermanaged, pain is associated with altered health-related quality of life. Therefore, this study aims to explore the biological, clinical, and social variables associated with chronic pain and its interference with hemodialysis patients.

METHODS

A cross-sectional study was conducted on Moroccan hemodialysis patients. A total of 307 patients participated in the study. Data collection was based on a structured questionnaire with sociodemographic, clinical, and dialysis variables. The Numeric Rating Scale and Brief Pain Inventory were used to assess pain characteristics.

RESULTS

Almost half of the hemodialysis had chronic pain, the mean pain severity and pain interference scores were 3.73 ± 3.59, and 22.89 ± 22.74 respectively. Multiple regression analysis revealed that gender (p = 0.022), number of comorbidities (p = 0.001), dialysis vintage (p < 0.001), number of pain sites (p < 0.001), and PTH level (p < 0.001) were associated with pain severity score. Older patients (p = 0.049), gender (p = 0.007), subjects with a number of comorbidities (p < 0.001), dialysis vintage (p < 0.001), number of pain sites (p < 0.001), and level of PTH (p < 0.001) were significantly associated with pain interference score.

CONCLUSIONS

The subgroups with increased pain severity were female hemodialysis, subjects living with multiple comorbid conditions, those with length dialysis vintage, a high number of painful sites, and increased PTH levels. Assessing and reducing pain intensity, pain interference, and its factors must be a priority for healthcare providers to manage pain and improve health-related quality of life.

Chronic musculoskeletal pain and its association with cognitive function and sarcopenia in older adults: Characterization and change over three months

Pain, cognitive impairment, and sarcopenia share common risk factors and neurophysiological processes, but studies investigating cognition and sarcopenia in older adults with pain are scarce. This study's main aim was to compare cognition and sarcopenia between older adults with and without chronic pain. A secondary aim was to investigate predictors of cognition and sarcopenia at baseline and 3 months while adjusting for confounders. Participants (67 older adults with pain and 67 asymptomatic older adults) were assessed for sociodemographic and clinical information, pain (number of painful body sites - body chart, pain phenotype - PainDETECT, severity and disability - BPI, pain catastrophizing - PCS, and kinesiophobia - Tampa Scale), cognition (MoCA), sarcopenia (risk of sarcopenia - SARC-F, hand grip strength, and calf circumference) and physical activity (RAPA) at baseline and 3 months after. Older adults with and without pain did not differ in cognition (Mean (95% CI): Pain = 21.47 (20.60; 22.34); Asymptomatic = 21.75 (20.89; 22.61)), but older adults with pain had greater signs of sarcopenia than asymptomatic older adults, including higher risk of sarcopenia (Mean (95%CI): Pain=2.89 (2.41; 3.37); Asymptomatic=0.50 (0.32; 0.68)) and lower hand grip strength (Pain=24.01 (21.74; 26.29); Asymptomatic=27.98 (25.80; 30.16)). No between-group differences were found for calf circumference (Pain=35.03 (34.26; 35.79); Asymptomatic=34.55 (33.86; 35.24)). Pain phenotype (baseline) and kinesiophobia (3 months) contributed to poorer cognition. Kinesiophobia and catastrophizing (baseline), and pain severity (3 months) contributed to sarcopenia. Despite no differences in cognition between older adults with and without pain, pain-related variables contributed to explaining sarcopenia and cognition. PERSPECTIVE: This study compared cognition and sarcopenia between older adults with and without pain and explored the association between pain, cognition, and sarcopenia. Groups were similar for cognition, but older adults with pain showed higher signs of sarcopenia. Kinesiophobia and pain severity partially explained cognition and sarcopenia among those with pain.

The brain-gut axis and chronic pain: mechanisms and therapeutic opportunities

The brain-gut axis (BGA) is emerging as a critical mediator in chronic pain, involving bidirectional communication between the central nervous system and the gastrointestinal system. The "Pain Matrix" is associated with microbial dysbiosis, vagus nerve dysfunction, and hypothalamic-pituitary-adrenal (HPA) axis dysregulation, driving neuroinflammation and central sensitization. Key mechanisms include microbial diversity loss, leaky gut, and altered neuroactive signaling via short-chain fatty acids (SCFAs) and vagal pathways. This narrative review explores the intricate interplay between BGA mechanisms and chronic pain, highlighting therapeutic opportunities such as restoring dysbiosis, modulating vagus nerve activity, and regulating endocrine pathways. These interventions target inflammation, autonomic balance, and stress/reward pathway modulation, offering a promising path toward integrative pain management. Further research is required to validate these strategies and improve patient outcomes.

Exploring the emotional impact of pain on children and adolescents: A poetic meta-ethnography

Pain in early life can go unreported and untreated. We use poems to portray findings from a systematic review of qualitative research. The overall aim of the review was to distil essential experiences across pain conditions and contexts. This report, focusing on the emotional impact of pain, is one of a series of three analyses from one systematic review of qualitative research. We used meta-ethnography to synthesise research. We identified studies in English that explored acute and/or chronic child and/or adolescent pain experience. Findings were distilled into themes and poems co-created in English and Spanish. We included 189 reports (177 unique studies) incorporating 5875 people (at least 3484 reported as female). Most studies (93%) included participants aged 11-20 years (range 2-38). The studies explored acute (24% studies), chronic (75%), and acute/chronic (1%). We report seven themes: (1) Pain can be hard to bear; (2) Pain is scary; (3) Pain is constantly at the back of my mind: (4) Pain makes me feel like I am outside alone; (5) Pain makes school a hard fit; (6) Pain can hurt me deep inside; (7) Pain has changed me. Our themes highlight the emotional impact of pain across conditions and contexts. Art and science are both integral to leaps in understanding. The contribution of the Arts is their unique ability to reach audiences on an affective level, giving the potential to underpin compassionate care and policy. We invite readers to utilise these poems to start a conversation about young people's pain experiences. This systematic review was registered on the PROSPERO database (CRD42023429027). Ethical permissions are not required for an evidence synthesis. PERSPECTIVE: The voices of young people in pain are not always heard. This article presents themes, in poetic form, from a synthesis of 189 qualitative studies. Science and art are integral to leaps in understanding and inclusive arts-based research methods have the potential to underpin compassionate pain care for young people.

Similarities and differences between chronic primary pain and depression in brain activities: Evidence from resting-state microstates and auditory Oddball task

BACKGROUND

In 2019, the International Association for the Study of Pain introduced the concept of 'chronic primary pain (CPP)', characterized by persistent non-organic pain with emotional and functional abnormalities. Underdiagnosed and linked to depression, CPP has poorly understood neural characteristics. Electroencephalogram (EEG) microstates enable detailed examination of brain network dynamics at the millisecond level. Incorporating task-related EEG features offers a comprehensive neurophysiological signature of brain dysfunction, facilitating exploration of potential neural mechanisms.

METHODS

This study employed resting-state and task-related auditory Oddball EEG paradigm to evaluate 20 healthy controls, 20 patients with depression, and 20 patients with CPP. An 8-minute recording of resting-state EEG was conducted to identify four typical microstates (A-D). Additionally, power spectral density (PSD) features were examined during an auditory Oddball paradigm.

RESULTS

Both CPP and Major Depressive Disorder (MDD) patients exhibited reduced occurrence rate and transition probabilities of other microstates to microstate C during resting-state EEG. Furthermore, more pronounced increase in Gamma PSD was observed in the occipital region of CPP during the Oddball task. In CPP, both resting-state microstate C and task-related Gamma PSD correlated with pain and emotional indicators. Notably, microstate C occurrence positively correlated with occipital Gamma PSD in MDD.

CONCLUSION

Conclusively, both CPP and MDD display dynamic abnormalities within the salient network, closely associated with pain and depressive symptoms in CPP. Unlike MDD, CPPs' dynamic network changes appear unrelated to perceptual integration function, indicating differing microstate functional impacts. Combining resting-state microstates and Oddball tasks may offer a promising avenue for identifying potential biomarkers in objectively assessing chronic primary pain.

Is poor dietary quality in adolescence a risk factor for painful temporomandibular disorders and headaches in young adulthood? A prospective study in the Danish National Birth Cohort

OBJECTIVE

To investigate the association between adolescents' dietary quality and the presence of painful temporomandibular disorder (p-TMD) and headaches in young adulthood.

BACKGROUND

P-TMD is a common orofacial pain condition often associated with headaches and discomfort. Some studies have shown that dietary behaviors can impact chronic musculoskeletal pain. Although various factors such as sex, age, psychosocial aspects, and pain sensitivity contribute to p-TMD, the role of nutrition remains unclear.

METHODS

The dietary quality of 32,247 singletons from the Danish National Birth Cohort (DNBC) at age 14 was assessed using the Healthy Eating Index (HEI) encompassing eight domains. Among these, 11,982 (37.1%) individuals completed the TMD pain screener and headache-related queries at age 18 and above. HEI and dietary domains were analyzed as potential risk factors for p-TMD and headaches.

RESULTS

P-TMD was present in 3163 of the 11,982 members of the study population. HEI scores were divided into quartiles, with quartile four indicating the highest dietary quality. Quartile four showed a higher odds ratio (OR) for p-TMD than quartile one (OR = 1.14 [95% confidence interval (CI), 1.01-1.29]), but the significance was lost after adjustment for confounders (adjusted OR [aOR] = 1.12 [95% CI, 0.97-1.30]). Overall dietary quality was not significantly associated with headaches. However, specific dietary quality domains, such as dietary fibers (aOR = 0.97 [95% CI, 0.95-0.99]), fish (aOR = 0.98 [95% CI, 0.97-1.00]), sodium (aOR = 1.03 [95% CI, 1.01-1.06]), and added sugar (aOR = 0.97 [95% CI, 0.95-0.99]) were associated with headaches but not with p-TMD after adjustment.

CONCLUSION

Overall adolescent dietary quality did not significantly associate with p-TMD or headaches in young adulthood after adjusting for confounders. However, specific dietary domains exhibited weak but statistically significant associations with headaches. These findings underscore the interplay between diet and pain, calling for further research to unveil the underlying pathophysiological mechanisms connecting lifestyle, p-TMD, and headaches.

What has brain diffusion magnetic resonance imaging taught us about chronic primary pain: a narrative review

ABSTRACT

Chronic pain is a pervasive and debilitating condition with increasing implications for public health, affecting millions of individuals worldwide. Despite its high prevalence, the underlying neural mechanisms and pathophysiology remain only partly understood. Since its introduction 35 years ago, brain diffusion magnetic resonance imaging (MRI) has emerged as a powerful tool to investigate changes in white matter microstructure and connectivity associated with chronic pain. This review synthesizes findings from 58 articles that constitute the current research landscape, covering methods and key discoveries. We discuss the evidence supporting the role of altered white matter microstructure and connectivity in chronic primary pain conditions, highlighting the importance of studying multiple chronic pain syndromes to identify common neurobiological pathways. We also explore the prospective clinical utility of diffusion MRI, such as its role in identifying diagnostic, prognostic, and therapeutic biomarkers. Furthermore, we address shortcomings and challenges associated with brain diffusion MRI in chronic primary pain studies, emphasizing the need for the harmonization of data acquisition and analysis methods. We conclude by highlighting emerging approaches and prospective avenues in the field that may provide new insights into the pathophysiology of chronic pain and potential new therapeutic targets. Because of the limited current body of research and unidentified targeted therapeutic strategies, we are forced to conclude that further research is required. However, we believe that brain diffusion MRI presents a promising opportunity for enhancing our understanding of chronic pain and improving clinical outcomes.

The role and treatment potential of the complement pathway in chronic pain

The role of the complement system in pain syndromes has garnered attention on the back of preclinical and clinical evidence supporting its potential as a target for new analgesic pharmacotherapies. Of the components that make up the complement system, component 5a (C5a) and component 3a (C3a) are most strongly and consistently associated with pain. Receptors for C5a are widely found in immune resident cells (microglia, astrocytes, sensory neuron-associated macrophages (sNAMs)) in the central nervous system (CNS) as well as hematogenous immune cells (mast cells, macrophages, T-lymphocytes, etc.). When active, as is often observed in chronic pain conditions, these cells produce various inflammatory mediators including pro-inflammatory cytokines. These events can trigger nervous tissue inflammation (neuroinflammation) which coexists with and potentially maintains peripheral and central sensitization. C5a has a likely critical role in initiating this process highlighting its potential as a promising non-opioid target for treating pain. This review summarizes the most up-to-date research on the role of the complement system in pain with emphasis on the C5 pathway in peripheral tissue, dorsal root ganglia (DRG) and the CNS, and explores advances in complement-targeted drug development and sex differences. A perspective on the optimal application of different C5a inhibitors for different types (e.g., neuropathic, post-surgical and chemotherapy-induced pain, osteoarthritis pain) and stages (e.g., acute, subacute, chronic) of pain is also provided to help guide future clinical trials. PERSPECTIVE: This review highlights the role and mechanisms of complement components and their receptors in physiological and pathological pain. The potential of complement-targeted therapeutics for the treatment of chronic pain is also explored with a focus on C5a inhibitors to help guide future clinical trials.

Pharmacological interventions for patients with chronic primary musculoskeletal pain: disparity between synthesized evidence and real-world clinical practice

Introduction

Chronic primary musculoskeletal pain (CPMP) poses a major problem of public health, with high prevalence rates and economic burden. There is a wealth of clinical trials examining pharmacological interventions for patients with CPMP. Nevertheless, evidence from such trials does not necessarily mirror clinical realities.

Objectives

We aimed to compare data sets from a clinical sample with an randomized controlled trial (RCT)-based sample.

Methods

Both data sets included participants living with CPMP who received pharmacological interventions. The clinical sample was retrieved from electronic health records. The RCT-based sample stemmed from a network meta-analysis project. The following outcomes were used: demographic information, diagnosis-specific data, and pharmacological interventions (categorized according to the World Health Organization [WHO] analgesic ladder).

Results

The clinical sample consisted of 103 patients (mean age: 50.25 years; SD: 14.0) and the RCT-based samples contributed 8665 participants (mean age: 51.97 years; SD: 6.74). In both samples, the proportion of women was higher than that of men (ie, 74.8% vs 58.9%). Psychiatric disorders were the most common comorbidities in the clinic sample but also the most frequent reason for patient exclusion in RCTs. The 2 samples differed significantly in medication classified as WHO III (clinical sample: 12.9%; RCT sample: 23.5%; P = 0.023) and WHO IV (clinical sample: 23.4%; RCT sample: 8.6%; P < 0.001), yet not WHO I and II.

Conclusion

Our findings suggest a disparity between research-based study populations and clinical populations with CPMP. We advocate for future investigations on how to implement robust scientific evidence into real-world clinical practice, with a particular focus on addressing psychiatric comorbidities.

Day-to-day associations between pain intensity and sleep outcomes in an adult chronic musculoskeletal pain population: A systematic review

BACKGROUND

In individuals with chronic musculoskeletal pain, a reciprocal relationship between sleep and pain across short and long-term evaluations exists. Sleep influences pain levels, while the level of pain also impairs sleep. However, given the day-to-day variability of both sleep and pain intensity, assessing this relationship within a daily time frame should be considered.

OBJECTIVES

To systematically review the literature concerning the bidirectional day-to-day relationship between night-time sleep variables and day-time pain intensity in individuals with chronic musculoskeletal pain.

METHODS

A systematic search (final search on October 12, 2023) in four databases (PubMed, Web of Science, Embase, PsycInfo) identified eligible articles based on pre-defined criteria. Three independent reviewers executed data extraction and risk of bias assessment using the "Quality In Prognosis Studies" tool. The study findings were synthesized narratively.

RESULTS

Eleven articles (1014 study participants; 83 associations) were included. A bidirectional relationship between pain intensity and sleep was found. Nine articles indicated night-time sleep quality to be a more consistent predictor for next day pain intensity than vice versa.

CONCLUSION

Nonetheless the bidirectional day-to-day sleep-pain relationship in individuals with chronic musculoskeletal pain, results suggest that self-reported sleep quality has a stronger predictive value on pain intensity then vice versa.

Harnessing the therapeutic effects of nature for chronic Pain: A role for immersive virtual reality? A narrative review

BACKGROUND AND OBJECTIVE

There is a growing interest in the relationship between nature and pain relief. Evidence from environmental psychology, neuroscience and physiology-based studies point towards analgesic effects of nature being mediated through various cognitive, affective and/or autonomic factors. Being able to harness these therapeutic effects using immersive virtual reality (VR) could help to optimize and improve accessibility of nature-based environments as part of chronic pain management plans. In this narrative review, we present evidence supporting a new theoretical framework for nature-based analgesia and suggest ways for applying this through immersive VR.

DATABASES AND DATA TREATMENT

We provide an overview of the evidence on (1) the therapeutic effects of nature on pain, (2) environmental psychology theory that underpins the health benefits of nature, (3) key mechanistic evidence from nature neuroimaging and physiology-based studies, (4) previous studies that have used VR-based nature in pain research and (5) how to design effective VR interventions that can be used to integrate nature into immersive 360 environments.

RESULTS

We have demonstrated how environmental psychology, neuroscience and physiology-based research can be used to form a novel theoretical framework for nature-based analgesia. Using this framework, we identify how key aspects of nature can act as analgesic and how this can be harnessed using immersive VR.

CONCLUSIONS

Through developing this theoretical framework, we have provided a foundation on which to guide future experimental and clinical studies as well as helping to improve the accessibility of nature for chronic pain patients through immersive VR technologies.

SIGNIFICANCE

This review article summarizes key multidisciplinary evidence to help understand how nature exerts beneficial effects on pain processing. The use of this theoretical framework alongside advances in immersive VR technologies provides a springboard for future research and can be used to help develop new nature-based therapeutics using VR.

Does pain influence control of muscle force? A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

In the presence of pain, whether clinical or experimentally induced, individuals commonly show impairments in the control of muscle force (commonly known as force steadiness). In this systematic review and meta-analysis, we synthesized the available evidence on the influence of clinical and experimental pain on force steadiness.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, PubMed, CINAHL Plus and Web of Science databases were searched from their inception to 19 December 2023, using MeSH terms and pre-selected keywords related to pain and force steadiness. Two independent reviewers screened studies for inclusion and assessed their methodological quality using a modified Newcastle-Ottawa risk of bias tool.

RESULTS

In total, 32 studies (19 clinical pain and 13 experimental pain) were included. Meta-analyses revealed reduced force steadiness in the presence of clinical pain as measured by the coefficient of variation (CoV) and standard deviation (SD) of force (standardized mean difference; SMD = 0.80, 95% CI = 0.31-1.28 and SMD = 0.61, 95% CI = 0.11-1.11). These findings were supported by moderate and low strength of evidence respectively. In the presence of experimental pain, meta-analyses revealed reductions in force steadiness when measured by the CoV of force but not by the SD of force (SMD = 0.50, 95% CI = 0.01-0.99; and SMD = 0.44, 95% CI = -0.04 to 0.92), each supported by very low strength of evidence.

CONCLUSIONS

This work demonstrates that pain, particularly clinical pain, impairs force steadiness. Such impairments likely have clinical relevance and could become targets for treatment when managing people experiencing musculoskeletal pain.

SIGNIFICANCE STATEMENT

This systematic review and meta-analyses enhances our understanding of motor impairments observed in people experiencing musculoskeletal pain. It underscores the significance of incorporating force steadiness assessment when managing individuals experiencing musculoskeletal pain. Additionally, it suggests that future research should explore the potential benefits of force steadiness training in alleviating patients' symptoms and enhancing their functional performance. This could potentially lead to the development of innovative therapeutic approaches for individuals suffering from musculoskeletal pain.

11th revision of the International Classification of Diseases chronic primary pain diagnoses in children and adolescents: representation of pediatric patients in the new classification system

ABSTRACT

Chronic pain is common among children and adolescents; however, the diagnoses in the newly developed 11th revision of the International Classification of Diseases (ICD-11) chronic pain chapter are based on adult criteria, overlooking pediatric neurodevelopmental differences. The chronic pain diagnoses have demonstrated good clinical applicability in adults, but to date, no field study has examined these diagnoses to the most specific diagnostic level in a pediatric sample. The current study aimed to explore pediatric representation within the ICD-11, with focus on chronic primary pain. Healthcare professionals (HCPs) at a specialized pediatric pain center documented the symptoms of and assigned both ICD-10 and ICD-11 diagnoses to N = 402 patients. Using criteria-based computer algorithms, specific ICD-11 pain diagnoses were allocated for each documented pain location, with residual diagnoses (ie, "unspecified") assigned if criteria were not (fully) met. Within the ICD-11, the algorithms assigned specific pain diagnoses to most patients (73.6%). In ICD-10, HCPs could not specify a diagnosis for 5.2% of patients; the ICD-11 algorithm allocated a residual chronic primary pain diagnosis in 51.2%. Residual categories were especially prevalent among younger children, boys, patients with headaches, and those with lower pain severity. Overall, clinical utility of the ICD-11 was high, although less effective for chronic back pain and headache diagnoses. The latter also exhibited the lowest agreement between HCPs and algorithm. The current study underscores the need for evidence-based improvements to the ICD-11 diagnostic criteria in pediatrics. Developing pediatric coding notes could improve the visibility of patients internationally and improve the likelihood of receiving reimbursement for necessary treatments through accurate coding.

Prediction models for treatment success after an interdisciplinary multimodal pain treatment program

Chronic musculoskeletal pain (CMP) poses a widespread health and socioeconomic problem, being the most prevalent chronic pain condition. Interdisciplinary multimodal pain treatment (IMPT) is considered the gold standard, offering cost-effective long-term care. Unfortunately, only a subset of patients experiences clinically relevant improvements in pain, fatigue, and disability post-IMPT. Establishing a prediction model encompassing various outcome measures could enhance rehabilitation and personalized healthcare. Thus, the aim was to develop and validate a prediction model for IMPT success in patients with CMP. A prospective cohort study within routine care was performed, including patients with CMP undergoing a 10-week IMPT. Success across four outcome measures was determined: patients' recovery perspective, quality of life (physical and mental), and disability. Sixty-five demographic and candidate predictors (mainly patient reported outcome measures) were examined. Finally, 2309 patients participated, with IMPT success rates ranging from 30% to 57%. Four models incorporating 33 predictors were developed, with treatment control being the sole consistent predictor across all models. Additionally, predictors effects varied in direction in the models. All models demonstrated strong calibration, fair to good discrimination, and were internally validated (optimism-corrected AUC range 0.69-0.80). Our findings show that treatment success can be predicted using standardized patient-reported measures, exhibiting strong discriminatory power. However, predictors vary depending on the outcome, underscoring the importance of selecting the appropriate measure upfront. Clinically, these results suggest potential for patient-centered care and may contribute to the development of a scientifically sound decision tool.

Fibromyalgia syndrome-a bodily distress disorder/somatic symptom disorder?

Introduction

The debate addressing the classification of chronic widespread pain as a physical disorder (fibromyalgia syndrome) [FMS] or a somatoform disorder according to psychiatric classification systems has continued for decades.

Objectives

The review aims to line out the new perspectives introduced by the 11th version of the International Classification of Diseases (ICD 11) of the World Health Organization (WHO).

Methods

Critical review of the classification criteria of fibromyalgia syndrome and bodily distress disorder in ICD 11.

Results

Fibromyalgia syndrome has been eliminated from the chapter of diseases of the musculoskeletal system and is now included in a chapter "Symptoms, signs, clinical forms, and abnormal clinical and laboratory findings, not elsewhere classified". Previously, the ICD-10 diagnosis of somatoform disorder was often used by mental health care disciplines instead of the label FMS. Somatoform disorders category has been eliminated as a diagnostic category in the ICD-11 and the 5th version Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association (APA) and has been replaced with the new categories of bodily distress disorder (BDD) and somatic symptom disorder (SSD) respectively. For diagnosis, these latter mental disorders require at least one distressing somatic symptom (e.g. pain) plus positive psychobehavioral criteria, namely "excessive thoughts, feelings, or behaviours related to the somatic symptoms or associated health concerns", without the condition that distressing somatic symptoms have to be medically unexplained.

Conclusion

We argue that the psychobehavioral criteria of BDD/SSD are imprecisely defined and can be misinterpreted as for "Excessive health concerns" which may occur due to the many uncertainties surrounding FMS or "Excessive time devoted to the symptoms" which may be related to patient self-management strategies.

Do biopsychosocial factors predict the level of physical activity in individuals with persistent shoulder pain?

OBJECTIVE

The objective of this cross-sectional study was to compare the physical activity level between individuals with and without rotator cuff related shoulder pain (RCRSP), and, in individuals with RCRSP, investigate whether biopsychosocial factors are associated with the physical activity level.

METHODS

Seventy-four participants with and 84 participants without RCRSP wore a fitness tracking watch for seven consecutive days to assess physical activity (step count, moderate-to-vigorous physical activity (MVPA)-minutes). Additionally, participants with RCRSP completed questionnaires on their level of pain, disability, and physical activity (short version of the International Physical Activity Questionnaire [IPAQ]), as well as on biopsychosocial factors, including resilience, stress, catastrophizing, anxiety and depressive symptoms, self-efficacy, and social support. Statistical analysis included Mann-Whitney U tests and General Linear Models for group comparisons, as well as multiple regression analyses to explore predictors of physical activity.

RESULTS

No significant between-group difference was found concerning step count and MVPA-minutes. Age and depressive symptoms explained 14% of the variance in step count, while age and resilience explained 15% of MVPA-minutes variance. Additionally, resilience was associated with IPAQ (P < 0.05), indicating that higher resilience correlates with greater reported physical activity (odds ratio: 2.32 [1.27, 4.22]).

CONCLUSION

While individuals with RCRSP did not show lower physical activity levels compared to their healthy counterparts, greater physical activity was associated with younger age, lower depressive symptoms, and higher resilience in individuals with RCRSP. Future research should explore whether resilience and physical activity interventions can prevent the transition to persistent RCRSP.

Prevalence of Spinal Segmental Sensitization Syndrome in Outpatients Attending Physical Medicine and Rehabilitation Centers for Chronic Musculoskeletal Pain: A Multicenter Study

OBJECTIVE

To determine the prevalence of spinal segmental sensitization (SSS) syndrome, a regional pain disorder, among patients visiting physical medicine and rehabilitation centers (PM&RCs) for chronic musculoskeletal pain (CMSP).

DESIGN

An observational, descriptive, cross-sectional study conducted from March to July 2023.

SETTING

Seven PM&RCs from 5 cities, representing 3 care systems: Social Security (SS), Ministry of Health (MH), and private practice (PP).

PARTICIPANTS

All patients, regardless of age, attending a physiatry consultation for CMSP for the first time and who provided informed consent to participate were included. Nonprobabilistic sampling was employed.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

We estimated the overall prevalence of SSS syndrome as a percentage among patients with CMSP, stratified by health care institution, sex, age, and occupation type. We also recorded the spinal segments involved and any concomitant painful disorders (CPDs). SSS syndrome was diagnosed using standardized criteria.

RESULTS

Of the eligible participants, 319 with CMSP were enrolled; 73.4% were women, and the median age of participants was 56.9 (range, 13-89y) years. The overall prevalence of SSS syndrome was 53.3%. Of these, 69.1%, 42.2%, and 13.8% were in the SS, MH, and PP systems, respectively. The most affected were female participants (56.4%), those aged 50-64 years (60.4%), and those with active jobs (58.8%). Most commonly, the lumbosacral and lumbar segments were affected, followed by the lower and middle cervical levels. Spine pathologies were the most common CPDs.

CONCLUSION

The prevalence of SSS syndrome was high among patients who visited PM&RCs for CMSP and varied according to the care system. Further research on SSS syndrome is warranted to relieve the burden it poses on patients with CMSP and ensure proper diagnosis in clinical practice.

Impaired somatosensory habituation in older adults with chronic pain during an affective oddball task

BACKGROUND

Chronic pain is one of the most common health conditions among older adults, triggering various disruptions in information processing across attentional, emotional, and somatosensory domains. However, there is insufficient information about how these aspects interact and their potential contribution to the vulnerability of older adults to chronic pain. This study aimed to investigate potential alterations induced by chronic pain during aging in attentional aspects of tactile stimulation and to observe the influence of affective context.

METHOD

Twenty-six older adults with chronic pain (70.00 ± 5.07 years; 11 males), 28 pain-free older adults (69.57 ± 3.96 years; 13 males) and 27 healthy younger adults (21.48 ± 1.80 years; 14 males) participated in the study. We compared the somatosensory evoked potentials elicited by frequent and deviant stimulation (probability 14%) applied when participants were viewing blocks of pleasant, unpleasant, and neutral images from the International Affective Picture System.

RESULTS

During frequent stimulation, older adults with chronic pain showed higher P50 and N100 amplitudes compared to pain-free older adults and younger individuals. Furthermore, the older group with pain exhibited higher P300 amplitude during emotional contexts compared to neutral scenarios. During deviant stimulation, older adults with chronic pain exhibited higher P50 and N100 amplitudes compared to pain-free older adults but displayed typical age-related flattening during P300.

CONCLUSIONS

These findings indicate that chronic pain leads to a decline in the ability to habituate to non-painful irrelevant somatosensory stimuli, especially when it is presented in an emotional context.

SIGNIFICANCE STATEMENT

In the present study, we have observed how older individuals suffering from chronic pain exhibit a decline in the habituation capacity of irrelevant somatosensory information. Furthermore, we have observed how the affective context in which these individuals are situated leads to an exacerbation of this deficit. Enhancing our comprehension of how aging and chronic pain interact to impact somatosensory processing could facilitate the tailoring of novel intervention strategies.

Comparative effectiveness of manual therapy, pharmacological treatment, exercise therapy, and education for neck pain (COMPETE study): protocol of a systematic review with network meta-analysis

BACKGROUND AND CONTEXT OF THE STUDY: Neck pain is a prevalent and globally burdensome problem. Clinical practice guidelines have recommended conservative treatments such as education, exercise therapy (ET), manual therapy (MT), and pharmacological therapy (i.e., medication) to manage all types of neck pain based on the chronicity of the disease (acute, subacute, and chronic pain). However, there is scarce evidence to determine which interventions constitute the most effective strategy for this condition. RESEARCH QUESTION: What are the best conservative treatment options (i.e., ET, MT, education, and/or medication) to relieve pain and disability-related outcomes in patients with neck pain? THE OVERALL PURPOSE OF THE STUDY: (1) To identify which type of conservative treatment (education, ET, MT, and/or medication) and their combinations have the greatest probability of being most effective for neck pain using a network meta-analysis (NMA) approach. (2) To rank these conservative treatments in terms of safety (when possible) and effectiveness for managing neck pain. METHODOLOGY: Systematic review (SR) with NMA of randomized controlled trials (RCTs). Studies should include adults (aged > 18) with neck pain who received any of the interventions of interest (education, ET, MT, and medication). The main outcome will be pain intensity. Searches will be conducted in Ovid Medline All®, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Scopus, and Cochrane Library Trials database. No language or publication date restrictions will be applied. The revised Cochrane Risk-of-Bias (RoB) tool for RCTs (RoB-2) will be used to evaluate RoB, and the certainty of evidence will be evaluated by Grading of Recommendations, Assessment, Development, and Evaluations (GRADE). NMAs will be conducted to rank interventions according to their effectiveness and safety (when possible), allowing a comprehensive analysis of all available evidence, with different nodes specified for all conservative interventions of interest, placebo, sham therapy, and non-intervention control. This NMA will help clinicians and the scientific community choose the most effective strategy or combinations of strategies for treating neck pain. The information gathered in this project will inform decision-making and guide personalized care of individual patients in the future.

Real-world implementation of pain science education and barriers to use in private practice physiotherapy settings: an Australia-wide cross-sectional survey

ABSTRACT

Physiotherapists are critically positioned to integrate education into patient care, including pain science education (PSE) to enhance management and outcomes. Anecdotally, many physiotherapists report difficulty providing PSE in private practice settings. Here, we aimed to explore current PSE use, knowledge, and barriers to implementation. A nationwide online (Qualtrics) survey of PSE-trained Australian private practice physiotherapists assessed use, knowledge (revised Neurophysiology of Pain Questionnaire [rNPQ]), concept application, implementation barriers, and resource awareness/use/preferences, exploring associations with individual/clinic-level factors (clinical experience, PSE training, work location). A total of 278 physiotherapists (62.9% female, 39.4 [11.8] years, 15.2 [11.6] years of experience, 37.2% rural/remote) completed the survey. Pain science knowledge (rNPQ: mean 10.4 [2.2]/13) and perceived PSE competence was high, although 30% supported inaccurate PSE concepts. Pain science education training via professional development course was associated with higher knowledge relative to university training (multivariable; β = 1.337, P < 0.001). Physiotherapists reported providing PSE to 61% of patients, with patient-related barriers (expecting other treatments: 94%; previous negative/contradictory PSE experiences: 89%), clinic-level barriers (time constraints: 77%; insufficient billing schedules: 57%), and clinician-specific barriers (difficulties identifying/addressing patient maladaptive beliefs/behaviours: 53%; cultural/demographic translation challenges: 46%) reported. Fewer years of clinical experience was associated with heightened worry that providing PSE might go wrong (multivariable; β = -0.034, P = 0.010) and/or damage therapeutic relationships (multivariable; β = -0.049, P < 0.001). Physiotherapists were aware of over 100 PSE resources, with varying levels of perceived use/effectiveness, yet were largely unaware of educational strategies. Physiotherapists called for reduced complexity and greater ability to individualise PSE resources. Findings will guide improvements in PSE training/resources, to maximise physiotherapists' confidence and preparedness to effectively implement PSE.

Chronic pain is a risk factor for all-cause and cancer-specific mortality in cancer survivors: a population-based cohort study

BACKGROUND

Evidence is lacking on whether chronic pain is related to the risk of cancer mortality. This study seeks to unveil the association between chronic pain and all-cause, cancer, as well as non-cancer death in cancer patients based on the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

Cancer survivors aged at least 20 (n = 1369) from 3 NHANES (1999-2004) cycles were encompassed. Chronic pain and cancer were determined through self-report. We employed records from the National Death Index for the determination of death status and reason. All-cause, cancer, and non-cancer deaths were primary outcomes. We used time-dependent ROC curve assessment to evaluate the predictive value of chronic pain for death in cancer patients.

RESULTS

Over a median 141-month follow-up (interquartile range: 61-201 months), 884 (64.57%) of 1,369 cancer sufferers died, of which 259 (18.91%) died from cancer, and 625 (45.65%) from other causes. Compared with non-chronic pain survivors, chronic pain correlated with elevated all-cause mortality (Hazard Ratio (HR), 1.40; 95% CI, 1.14-1.72, p = 0.001) and cancer death (HR, 1.75; 95% CI, 1.16-2.64, p = 0.008), primarily in patients with pain lasting 3 months or more. Chronic pain was related to higher non-cancer mortality (HR, 1.38; 95% CI, 1.04-1.82, p = 0.025), and no significant results were found in pain duration. Time-dependent ROC curves showed the area under the curve (AUC) for all-cause mortality at 1, 3, 5, 10, and 20-year survival for chronic pain of 0.71, 0.78, 0.84, 0.89, and 0.96, respectively. The AUCs for cancer mortality at 1, 3, 5, 10, and 20-year for chronic pain were 0.83, 0.87, 0.91, 0.94, and 0.95, respectively, and those for non-cancer mortality at 1, 3, 5, 10, and 20-year for chronic pain were 0.82, 0.86, 0.90, 0.91, and 0.97, respectively.

CONCLUSION

Chronic pain is associated with heightened all-cause and cancer mortality in the cancer population. Clinical staff should focus on chronic pain in this patient population.

Incidence of chronic pelvic pain after childbirth and its causal association with C-section

ABSTRACT

This study aimed to report the incidence of chronic pelvic pain in women 12 to 24 months postpartum, to identify the independently associated factors, and to conduct a causal inference with C-section as the exposure. This was a cross-sectional study nested within 2 distinct prospective cohorts from 2 Brazilian cities. Chronic pelvic pain was the dependent variable. Independent variables were collected. Fisher exact test or Pearson χ2 test and t test or Wilcoxon rank-sum test were performed as appropriate, with P-values adjusted. Data were assumed to be missing at random, and multivariate imputation by chained equations was performed. Sensitivity analysis was conducted using complete cases. Multicollinearity was assessed by computing the variance inflation factor. Binomial logistic regression was used to obtain an interpretable model. Odds ratios and 95% confidence intervals were used as measurements. A directed acyclic graph was used for causal inference. A total of 2160 women were included. The incidence of chronic pelvic pain was 12.7%. C-sections doubled the odds of developing chronic pelvic pain (CPP). Additional factors associated with increased odds included city of birth, feelings of discrimination, severe symptoms of anxiety, dissatisfaction with the care received during childbirth, and mental suffering. Women who underwent C-sections had a 6.1% higher incidence of CPP compared to those who did not undergo the procedure. The incidence of CPP postpartum is high, and there is a potential causal effect of C-sections. City of birth, discrimination, anxiety, dissatisfaction with the care, and mental suffering were also associated with an increased odds.

Social prescribing for adults with chronic pain in the U.K.: a rapid review

Introduction

Social prescribing links patients to community groups and services to meet health needs; however, it is uncertain what the benefits and impacts of social prescribing are for people with chronic pain. The National Institute for Health and Care Excellence (NICE) undertook a systematic review to investigate the clinical and cost effectiveness of social interventions aimed at improving the quality of life of people with chronic pain; no relevant clinical studies comparing social interventions with standard care for chronic pain were found, though the inclusion criteria for studies was narrow.

Objectives

To undertake a rapid review of all types of research and policy on social prescribing for adults with chronic pain in the U.K. (i) to describe the characteristics of relevant research and (ii) to synthesise data on impact.

Methods

A two-stage rapid review was planned. Stage (i) scoped and categorised knowledge from a comprehensive representation of the literature. In stage (ii), we undertook a descriptive synthesis of quantitative data along with a thematic analysis of qualitative data identified by stage (i).

Results

Of 40 full-text records assessed for inclusion, three met the inclusion criteria from academic databases. An additional five records were found in grey literature. Six records reported quantitative findings suggesting that social prescribing reduced pain severity and discomfort, pain medication and clinical appointments; and improved quality of life and ability to manage health. Five records captured qualitative data from interviews, case studies and anecdotal quotes that suggested positive impact on health and wellbeing; and increased self-efficacy in social prescribers undertaking training on pain.

Conclusions

There is tentative evidence that social prescribing improves health and wellbeing outcomes in adults with chronic pain and that there is a need to upskill social prescribers in contemporary pain science education. Research on the routes to referral, outcomes and impacts is needed.

Perspective

Social prescribing is valued and may be of benefit for people with chronic pain. There is a need to further develop and evaluate social prescribing services for people with chronic pain to enhance holistic patient centered care.

Exploring the therapeutic potential of TRPC channels in chronic pain: An investigation into their mechanisms, functions, and prospects

Transient Receptor Potential Canonical (TRPC) channels have received more attention in recent years for their role of in the pathophysiology of chronic pain. These non-selective cation channels, which are predominantly present on cell membranes, play a pivotal role in regulating both physiological and pathological processes. Research advances have shown the critical role of TRPC channels in a variety of chronic pain, including neuropathic, inflammatory, and visceral pain. Activation of TRPC channels increases neuronal excitability, amplifying and prolonging pain signals. Moreover, these channels collaborate with other ion channels and receptors to form complexes that augment the transmission and perception of pain. As research advances, our understanding of TRPC channels' regulation mechanisms and signaling pathways improves. An expanding variety of TRPC modulators has been identified as promising therapeutic agents for chronic pain, opening up novel treatment options. Nevertheless, the diversity and complexity of TRPC channels present challenges in drug development, highlighting the importance of full understanding of their unique properties and activities. This review aims to provide a thorough evaluation of recent breakthrough in TRPC channels research related to chronic pain, with a focus on their mechanisms, functions, and prospective therapeutic application. By integrating existing research findings, we seek to bring new viewpoints and approaches for chronic pain management.

Chronic overlapping pain conditions and nociplastic pain

Chronic overlapping pain conditions (COPCs) are a subset of chronic pain conditions commonly comorbid with one another and more prevalent in women and individuals assigned female at birth (AFAB). Pain experience in these conditions may better fit with a new mechanistic pain descriptor, nociplastic pain, and nociplastic pain may represent a shared underlying factor among COPCs. We applied GenomicSEM common-factor genome-wide association study (GWAS) and multivariate transcriptome-wide association (TWAS) analyses to existing GWAS output for six COPCs in order to find genetic variation associated with nociplastic pain, followed by genetic correlation (linkage disequilibrium score regression), gene set, and tissue enrichment analyses. We found 24 independent single nucleotide polymorphisms (SNPs), and 127 unique genes significantly associated with nociplastic pain, and showed nociplastic pain to be a polygenic trait with significant SNP heritability. We found significant genetic overlap between multisite chronic pain and nociplastic pain, and to a smaller extent with rheumatoid arthritis and a neuropathic pain phenotype. Tissue enrichment analyses highlighted cardiac and thyroid tissue, and gene set enrichment analyses emphasized potential shared mechanisms in cognitive, personality, and metabolic traits and nociplastic pain along with distinct pathology in migraine and headache. We used a well-powered network approach to investigate nociplastic pain using existing COPC GWAS output, and show nociplastic pain to be a complex, heritable trait, in addition to contributing to understanding of potential mechanisms in development of nociplastic pain.

Differences in Plasma BDNF Levels Between Chronic Primary Musculoskeletal Pain, Fibromyalgia Syndrome, and Asymptomatic Subjects: A Cross-Sectional Study

This cross-sectional study compared plasma brain-derived neurotrophic factor (BDNF) levels among chronic primary musculoskeletal pain patients, chronic widespread pain patients, and asymptomatic controls. The study included 126 participants aged 18-65, divided into three groups of 42 each. Pain intensity was assessed using a Numeric Rating Scale (NRS), and plasma BDNF levels were measured via ELISA. Differences between groups were evaluated using ANOVA with 2000 bootstrap resamples and a bias-corrected and accelerated method. Results showed significantly higher plasma BDNF levels in chronic widespread pain patients (mean difference [MD] = 0.44; 95% CI = 0.28, 0.62; p < .001) compared to controls, and higher than in chronic primary musculoskeletal pain patients (MD = 0.83; 95% CI = 0.64, 1.02; p < .001). Chronic primary musculoskeletal pain patients had lower plasma BDNF levels compared to controls (MD = -0.39; 95% CI = -0.54, -0.24; p < .001). No significant correlations were observed between plasma BDNF levels and clinical variables. These findings suggest the potential of BDNF as a biomarker to differentiate chronic primary pain conditions.

The Economic Analysis of the Overlooked Recurrent Low Back Pain: Three Years Retrospective Observational Study

Purpose

Recent redefinitions of pain emphasize the importance of the previously overlooked recurrent low back pain (LBP). Understanding the direct medical cost for recurrent LBP cases based on the cost per visit is crucial economically. We aimed to compare the cost per visit for LBP and recurrent LBP, including the impact of gender and type of medical service, estimating the approximate annual cost of recurrent LBP.

Patients and Methods

Data on LBP categorized according to ICD-10 codes (G54, G55, M45, M46, M47, M48, M49, M51, M53, and M54) from the Polish National Health Fund (NHF) and Opolskie Rehabilitation Center (OCR) were analyzed based on the recurrent state as outlined in the new chronic pain definition.

Results

In OCR, a recurrent LBP was confirmed for 22.78% of patients, of which 59.72% were female (p<0.001). The mean value of a single procedure for recurrent LBP was 110.56 EUR, it was significantly higher for males (135.35 EUR) than for females (92.94 EUR) (p=0.008). Recurrent LBP generated a higher cost per visit for medical services than LBP (p<0.001), except for physiotherapy. Notably, males had a higher cost per visit in inpatient admissions, while females had a significantly higher cost per visit in physiotherapy services for both LBP and recurrent LBP. Moreover, recurrent LBP generated a statistically higher cost per visit for medical services than non-recurrent cases, except for physiotherapy. The average annual cost of LBP-related medical services in Poland was €243,861,639.

Conclusion

Recurrent LBP accounts for 5% of total direct LBP costs and has a higher cost per visit than LBP, excluding physiotherapy services. Gender significantly affected per-visit costs, with males having more inpatient admissions and females utilizing more physiotherapy services for both LBP and recurrent LBP.

Impact of Nasal Anatomical Variation Subtype on Surgical Outcomes for Rhinogenic Contact Point Headache

Background/Objectives: Rhinogenic contact point headache (RCPH) is a controversial secondary headache disorder involving mucosal contact points in the nasal sinuses. The efficacy of surgical versus medical management has been debated, with some studies showing excellent long-term outcomes but others citing placebo effects. This study aimed to clarify the correlation with nasal anatomical variation detected by CT and RCPH treatment outcomes. Methods: A prospective cohort study was conducted on 90 RCPH patients undergoing surgery or medical therapy. Patients were diagnosed using CT scans, endoscopy, and lidocaine testing. The surgery group had endoscopic procedures to remove contact points. The medical group received intranasal steroids. Outcomes were measured by visual analog scale (VAS) for pain and headache frequency. Predictors like age, gender, and nasal anatomical variations were analyzed. Results: The surgery group showed significant reductions in VAS scores (6.02 to 2.51, p < 0.001) and headache frequency (9.11 to 3.04, p < 0.001). The medical group did not improve significantly. All nasal subtypes improved with surgery but concha bullosa had worse VAS outcomes (4.0) than septal deviation (1.8, p < 0.001) or spur (1.73, p < 0.001). Multivariate analysis found nasal anomalies predicted postoperative VAS scores (p < 0.001) but not headache frequency (p = 0.255). Conclusions: Surgery demonstrated superiority over medications for RCPH. This study provides new evidence that preoperative CT scans should be considered a non-invasive gold standard for analyzing nasal subtypes as they significantly influence surgical success, with concha bullosa associated with worse pain relief. Larger studies should validate these findings to optimize RCPH management.

Clinical Efficacy of Virtual Reality Cave Automatic Virtual Environments (CAVE) for Chronic Musculoskeletal Pain in Older Adults: A Randomized Controlled Trial

OBJECTIVES

To assess whether tai chi assisted by the Cave Automatic Virtual Environment (CAVE), a novel virtual reality (VR) technology, was superior to tai chi alone in managing chronic pain in older adults. CAVE may offer a promising alternative to head-mounted displays in chronic pain treatment.

DESIGN

The study was a 12-week, 2-arm, parallel, randomized controlled trial implemented in VR and non-VR groups (N = 80, each arm = 40). The VR group underwent an 8-week tai chi program in a 3-wall VR-CAVE with projections of nature scenes and music, whereas the control group received tai chi only.

SETTING AND PARTICIPANTS

Community-dwelling older adults with chronic musculoskeletal pain were randomized (1:1) to VR and non-VR groups.

MEASURES

Participants were assessed at baseline, posttreatment at 8 weeks, and 12 weeks. The primary outcome was the Brief Pain Inventory severity score at 8 weeks, modeled within an intention-to-treat framework using generalized estimating equations.

RESULTS

Participants had a mean age of 65.1 ± 5.6 years, with 78.8% female and mean BPI-pain severity score of 4.4 ± 1.5. At 8 weeks, the VR group demonstrated a statistically significant improvement in BPI severity score compared with the non-VR group (β = -0.75, 95% CI -1.48 to -0.03, P = .043), with the effect sustained to 12 weeks (β = -1.18, 95% CI -1.90 to -0.46, P = .001). No major adverse events were reported.

CONCLUSIONS AND IMPLICATIONS

VR-CAVE tai chi was superior to non-VR tai chi for chronic musculoskeletal pain. Future trials that are longer-term, larger in scale, and include other forms of exercise will further inform VR-CAVE's role in post-acute and long-term rehabilitation.

Beyond the chronic pain stage: default mode network perturbation depends on years lived with back pain

ABSTRACT

Research has indicated that the default mode network (DMN) is perturbated in patients with chronic pain when compared with healthy controls, and this perturbation is correlated with the duration of pain during the chronic pain stage. It remains unclear whether DMN adaptations manifest during the subacute pain stage and progress over time because of the duration of pain experience, rather than being a specific correlate of the chronic pain stage. Furthermore, information regarding whether these adaptations are related to cognitive processes of adaptation is lacking. To this end, we examined the DMN in 31 patients with chronic back pain (CBP), 77 patients with subacute back pain (SBP), as well as 39 healthy pain-free controls (HC) applying a graph-theoretic network approach on functional resting-state magnetic resonance imaging. Beyond the comparison between groups, we used a linear analysis considering the years lived with pain (YLP) across all patients with back pain and additionally performed a mediation analysis of the role of cognitive pain coping. In line with previous studies, we found significant DMN perturbation in CBP compared with HC. However, this did not apply to the comparison of CBP with SBP. Instead, we observed a positive correlation between DMN perturbation and YLP. This was significantly mediated by coping attitudes towards pain. Default mode network perturbation may thus reflect neural adaptation processes to pain experience rather than a single correlate of the chronic pain stage and be modulated by cognitive adaption. This points to potentially underinvestigated significant adaptation processes that could enable more fine-grained patient stratification.

How Well Can We Measure Chronic Pain Impact in Existing Longitudinal Cohort Studies? Lessons Learned

Multiple large longitudinal cohorts provide opportunities to address questions about predictors of pain and pain trajectories, even when not anticipated in the design of the historical databases. This focus article uses 2 empirical examples to illustrate the processes of assessing the measurement properties of data from large cohort studies to answer questions about pain. In both examples, data were screened to select candidate variables that captured the impact of chronic pain on self-care activities, productivity, and social activities. We describe a series of steps to select candidate items and evaluate their psychometric characteristics in relation to the measurement of pain impact proposed. In the UK Biobank, a general lack of internal consistency of variables selected prevented the identification of a satisfactory measurement model, with lessons for the measurement of chronic pain impact. In the English Longitudinal Study of Ageing, a measurement model for chronic pain impact was identified, albeit limited to capturing the impact of pain on self-care and productivity but lacking coverage related to social participation. In conjunction with its Supplementary Material, this focus article aims to encourage exploration of these valuable prospectively collected data to support researchers to make explicit the relationships between items in the databases and constructs of interest in pain research and to use empirical methods to estimate the possible biases in these variables. PERSPECTIVE: This focus article outlines a theory-driven approach for fitting new measurement models to data from large cohort studies and evaluating their psychometric properties. This aims to help researchers develop an empirical understanding of the gains and limitations connected with the process of repurposing the data stored in these datasets.

The measurement of "high-impact chronic pain": Limitations and alternative methods

OBJECTIVE

Chronic pain is known to be an important construct in clinical practice and a particular form of chronic pain, high-impact chronic pain (HICP), has gained recent interest and attention by pain clinicians, epidemiologists, and clinical researchers. The purpose of our Topical Review is to describe the historical development of measures of HICP and to explore the psychometric properties of HICP as well as to present alternative measurement methods.

METHODS

We identified strengths and weaknesses of the psychometric characteristics of HICP measures. Limitations of existing HICP measures were discussed and summarized and alternatives to current methods were proposed.

RESULTS

HICP operational definitions show variability across studies. All definitions cannot be correct, but which ones are incorrect cannot be determined as there is no gold standard. Random measurement error and recall bias are among the other limitations of current HICP measures. Model-based definitions of HICP, the discrete (for epidemiologic applications) and continuous (for clinical applications) latent variable models are discussed as likely superior alternatives to current methods.

CONCLUSIONS

Limitations of existing HICP methods are discussed and alternative development approaches to HICP measures are presented. The use of either discrete or continuous latent variable models would improve upon the psychometric characteristics of current HICP evidence. Examples are used to illustrate the benefits of latent variable models over traditional observed variable conceptualizations as the measurement of HICP continues to develop.

SIGNIFICANCE STATEMENT

This work takes the position that current methods of measuring high impact chronic pain (HICP) likely contain substantial error. We have endorsed an alternative approach for several psychometrically grounded reasons. We recommend that future work consider the discrete latent variable framework for dichotomous measures of HICP and the continuous latent variable framework for continuous measures of HICP. The paper provides illustrative examples of these methods for a different patient reported measure that is lacking a gold standard, much like HICP measures.

Application of the grading system for "nociplastic pain" in chronic primary and chronic secondary pain conditions: a field study

ABSTRACT

The concept "nociplastic pain" has been developed for patients with features of nociceptive system sensitization that are not explained as nociceptive or neuropathic. Here, we tested how well the recently published grading system differentiates between chronic primary and secondary pain conditions. We recruited patients with fibromyalgia (FMS, n = 41), complex regional pain syndrome (CRPS, n = 11), osteoarthritis (OA, n = 21), or peripheral nerve injury (PNI, n = 8). We used clinical history, pain drawings, quantitative sensory testing (QST), and questionnaires to classify their pains as possibly or probably "nociplastic." All patients with chronic primary pain exhibited widespread/regional pain not explainable by either nociceptive or neuropathic mechanisms. Widespread pain occurred in 12 patients with OA but was identified as nociceptive in 11 of 12. Regional pain occurred in 4 patients with PNI but was identified as neuropathic in 3 of 4. At this step, the grading system had 100% sensitivity and 93% specificity. Clinical evidence for pain hypersensitivity by QST, and history of hypersensitivity and mental comorbidities did not differentiate between chronic primary pain (QST: 36/52 = 69%, history: 43/52 = 83%) and secondary pain conditions (QST: 20/29 = 69%, history: 24/29 83%). Based on these data, specificity remained excellent (93%), but sensitivity dropped substantially (60%) due to lacking evidence for pain hypersensitivity in many patients with FMS. This low sensitivity suggests that the published grading system is not suitable for screening purposes. We suggest structural and content modifications to improve sensitivity, including placement of patient history before clinical examination and addition of a high tender point count as evidence for widespread pain hypersensitivity.

The Effectiveness of Auricular Acupressure on Chronic Musculoskeletal Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objectives: To assess the effectiveness of auricular acupressure (AA) in managing pain and disability in individuals with chronic musculoskeletal pain. Materials and Methods: A systematic search on six electronic databases was performed from their inception to May 7, 2023, to identified relevant randomized controlled trials (RCTs). Two independent reviewers screened the abstracts and full texts, extracted data, and assessed risk of bias using RoB 2. The primary outcomes were pain intensity and disability. The secondary outcomes were pain pressure thresholds, pain catastrophizing level, and fear avoidance beliefs. A random-effects model was used for meta-analyses. The certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation. Sensitivity analyses were conducted after removing low-quality papers. Results: Of 633 identified records, six studies involving 496 participants were included. All included studies compared the effectiveness of AA with sham controls in treating various chronic musculoskeletal pain. Four meta-analyses were conducted to compare the effectiveness of AA with sham controls. Low-quality evidence supported that AA had a large effect size on postintervention subjective pain reduction (standardized mean difference [SMD] = -0.95; 95% confidence interval [CI]: -1.36 to -0.54; p = 0.00; I2 = 52.61%); moderate-quality evidence substantiated that AA had a large effect size on enhancing postintervention pressure pain threshold (SMD = -0.55; 95% CI: -0.88 to -0.23; p = 0.00; I2 = 0%). There was low-quality evidence that AA had a large effect on reducing postintervention disability (SMD = -0.68; 95% CI: -1.24 to -0.12; p = 0.02; I2 = 51.33%). Our sensitivity analysis reaffirmed the same conclusion regarding pain reduction immediately after the intervention. Fourteen participants reported minimal adverse events, including soreness, tenderness, irritation, and redness, which disappeared within 1-7 days. Discussion: Our systematic review revealed that AA significantly improved pain, pressure pain thresholds, and disability in individuals with various chronic musculoskeletal pain conditions immediately post-treatment compared with sham treatment. Given the paucity of studies and inconsistent protocols, future RCTs are warranted to evaluate the effectiveness of AA in people with chronic musculoskeletal pain at a longer follow-up with detailed protocols, which allows researchers and clinicians to optimize AA intervention. Conclusion: AA has immediate post-treatment benefits for chronic musculoskeletal pain, whereas its effects at the 1- or 6-month follow-up remain uncertain.

Effectiveness of non-invasive vagus nerve stimulation vs heart rate variability biofeedback interventions for chronic pain conditions: A systematic review

OBJECTIVES

Autonomic regulation has been identified as a potential regulator of pain via vagal nerve mediation, assessed through heart rate variability (HRV). Non-invasive vagal nerve stimulation (nVNS) and heart rate variability biofeedback (HRVB) have been proposed to modulate pain. A limited number of studies compare nVNS and HRVB in persons with chronic pain conditions. This systematic review compared interventions of nVNS and HRVB in adults with long-standing pain conditions.

METHODS

PubMed, MEDLINE, CINAHL, SPORTDiscus, Google Scholar, and Cochrane library were used to retrieve the randomized controlled trials for this review between the years 2010 and 2023. Search terms included chronic pain, fibromyalgia, headache, migraine, vagus nerve stimulation, biofeedback, HRV, pain assessment, pain, and transcutaneous.

RESULTS

Ten full-text articles of 1,474 identified were selected for full qualitative synthesis, with a combined population of 813 subjects. There were n = 763 subjects in studies of nVNS and n = 50 subjects for HRVB. Six of the nine nVNS studies looked at headache disorders and migraines (n = 603), with two investigating effects on fibromyalgia symptoms (n = 138) and one the effects on chronic low back pain (n = 22). Of the nVNS studies, three demonstrated significant results in episode frequency, six in pain intensity (PI) reduction, and three in reduced medication use. The HRVB study showed statistically significant findings for reduced PI, depression scores, and increased HRV coherence.

CONCLUSION

Moderate to high-quality evidence suggests that nVNS is beneficial in reducing headache frequency and is well-tolerated, indicating it might be an alternative intervention to medication. HRVB interventions are beneficial in reducing pain, depression scores, use of non-steroidal anti-inflammatory medication, and in increasing HRV coherence ratio. HRVB and nVNS appear to show clinical benefits for chronic pain conditions; however, insufficient literature exists to support either approach.