Chronic pain patients can be classified into four groups: Clustering-based discriminant analysis of psychometric data from 4665 patients referred to a multidisciplinary pain centre (a SQRP study)

Body awareness and cognitive behavioral therapy for multisite musculoskeletal pain: patients` experiences with group rehabilitation

BACKGROUND

An extended group program called Mind and Body (MB), based on body awareness exercises and cognitive behavioral therapy (CBT), was offered to a subgroup of patients who had completed their traditional outpatient multidisciplinary rehabilitation and were motivated for further treatment.

PURPOSE

To explore how patients with multisite musculoskeletal pain experienced participation in the MB program with respect to usefulness, meaningfulness, behavioral changes, and transferability to daily life and work.

METHOD

The study is rooted in the phenomenological tradition. Individual, semi-structured interviews were performed with eight patients aged 29-56 years. The data were analyzed using systematic text condensation.

RESULTS

Two main themes emerged: 1) New knowledge provided increased body awareness, new ways of thinking, and acceptance of one's own situation. This theme reflected how new knowledge and MB coping strategies were useful in the process of changing problematic thoughts, increasing body awareness, and facilitating acceptance; and 2) Implementing new habits and strategies in daily life revealed how demanding it was to alter behavior, a process that unfolded over time.

CONCLUSION

A combination of body awareness exercises and cognitive coping strategies was described as helpful in further improving function and coping with pain and stress in daily life and work.

Eleven neurology-related proteins measured in serum are positively correlated to the severity of diabetic neuropathy

About 20% of patients with diabetes suffer from chronic pain with neuropathic characteristics. We investigated the multivariate associations between 92 neurology-related proteins measured in serum from 190 patients with painful and painless diabetic neuropathy. Participants were recruited from the Pain in Neuropathy Study, an observational cross-sectional multicentre study in which participants underwent deep phenotyping. In the exploration cohort, two groups were defined by hierarchical cluster analyses of protein data. The proportion of painless vs painful neuropathy did not differ between the two groups, but one group had a significantly higher grade of neuropathy as measured by the Toronto Clinical Scoring System (TCSS). This finding was replicated in the replication cohort. Analyzing both groups together, we found that a group of 11 inter-correlated proteins (TNFRSF12A, SCARB2, N2DL-2, SKR3, EFNA4, LAYN, CLM-1, CD38, UNC5C, GFR-alpha-1, and JAM-B) were positively associated with TCSS values. Notably, EFNA4 and UNC5C are known to be part of axon guidance pathways. To conclude, although cluster analysis of 92 neurology-related proteins did not distinguish painful from painless diabetic neuropathy, we identified 11 proteins which positively correlated to neuropathy severity and warrant further investigation as potential biomarkers.

The Impact of Non-Pain Factors on Pain Interference Among U.S. Service Members and Veterans with Symptoms of Mild Traumatic Brain Injury

U.S. Service members and Veterans (SM/V) experience elevated rates of traumatic brain injury (TBI), chronic pain, and other non-pain symptoms. However, the role of non-pain factors on pain interference levels remains unclear among SM/Vs, particularly those with a history of TBI. The primary objective of this study was to identify factors that differentiate high/low pain interference, given equivalent pain intensity among U.S. SM/V participating in the ongoing Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium (LIMBIC-CENC) national multi-center prospective longitudinal observational study. An explainable machine learning was used to identify key predictors of pain interference conditioned on equivalent pain intensity. The final sample consisted of n = 1,577 SM/Vs who were predominantly male (87%), and 83.6% had a history of mild TBI(s) (mTBI), while 16.4% were TBI negative controls. The sample was categorized according to pain interference level (Low: 19.9%, Moderate: 52.5%, and High: 27.6%). Both pain intensity scores and pain interference scores increased with the number of mTBIs (p < 0.001), and there was evidence of a dose response between the number of injuries and pain scores. Machine learning models identified fatigue and anxiety as the most important predictors of pain interference, whereas emotional control was protective. Partial dependence plots identified that marginal effects of fatigue and anxiety were associated with pain interference (p < 0.001), but the marginal effect of mTBI was not significant in models considering all variables (p > 0.05). Non-pain factors are associated with functional limitations and disability experience among SM/V with an mTBI history. The functional effects of pain may be mediated through multiple other factors. Pain is a multi-dimensional experience that may benefit most from holistic treatment approaches that target comorbidities and build supports that promote recovery.

The new chronic pain MG30 category and diagnostic specificity in quality registries-problems and suggested solutions with special reference to Swedish Quality Registry for Pain rehabilitation (SQRP)

The Swedish Quality Registry for Pain rehabilitation (SQRP) is a well-established clinical registry for adult patients with complex chronic pain conditions. SQRP registers patient-reported outcome measures from a majority of specialist chronic pain units/departments in Sweden. Up to four International Classification of Diseases version 10 (ICD-10) diagnoses can be registered in SQRP. The aim of the paper is to describe how we envision the new chronic pain category MG30 in ICD-11 can be used in SQRP. We envision that the first diagnosis in SQRP shall always be a MG30 diagnosis, which will ensure broad implementation of ICD-11 in Swedish pain care. However, at first glance, there seems to be specificity problems with ICD-11 codes that might impair their useability in SQRP or other registries. But ICD-11 offers more than meets the eye. First, the entries at the level of the so-called foundational layer have unique resource identifiers (URI) that can be used to enhance specificity. Second, ICD-11 contains numerous extension codes that can be combined with the MG30 codes - for instance, concerning the anatomical location of pain. Third, to enrich the description of the clinical concept at hand, it is possible to create clusters of stem codes. These three options are briefly discussed. We conclude that the full potential of the MG30 category can be better exploited in registries such as SQRP if foundational codes, extension codes, and/or clustering of stem codes are used to enhance diagnostic specificity.

Multidisciplinary strategies to treat painful mononeuropathies in the upper extremity: from lab to bedside

Neuropathic pain in the upper extremity is a serious problem, commonly involving relatively young patients. The pain causes loss of function and productivity, changes a patient's lifestyle and can progress into a chronic pain syndrome with secondary psychosocial co-morbidities. Treating patients with a painful mononeuropathy remains challenging, with a monodisciplinary approach often having limited treatment efficacy. This narrative review discusses how to deal with this challenge in the treatment of patients with peripheral nerve injury pain, addressing the four important pillars: (1) diagnosing a painful mononeuropathy; (2) clinical pain phenotyping; (3) personalized pain treatment; and (4) using a multidisciplinary team approach.

Prognostic subgroups of chronic pain patients using latent variable mixture modeling within a supervised machine learning framework

The present study combined a supervised machine learning framework with an unsupervised method, finite mixture modeling, to identify prognostically meaningful subgroups of diverse chronic pain patients undergoing interdisciplinary treatment. Questionnaire data collected at pre-treatment and 1-year follow up from 11,995 patients from the Swedish Quality Registry for Pain Rehabilitation were used. Indicators measuring pain characteristics, psychological aspects, and social functioning and general health status were used to form subgroups, and pain interference at follow-up was used for the selection and the performance evaluation of models. A nested cross-validation procedure was used for determining the number of classes (inner cross-validation) and the prediction accuracy of the selected model among unseen cases (outer cross-validation). A four-class solution was identified as the optimal model. Identified subgroups were separable on indicators, predictive of long-term outcomes, and related to background characteristics. Results are discussed in relation to previous clustering attempts of patients with diverse chronic pain conditions. Our analytical approach, as the first to combine mixture modeling with supervised, targeted learning, provides a promising framework that can be further extended and optimized for improving accurate prognosis in pain treatment and identifying clinically meaningful subgroups among chronic pain patients.

Cracking the Chronic Pain code: A scoping review of Artificial Intelligence in Chronic Pain research

OBJECTIVE

The aim of this review is to identify gaps and provide a direction for future research in the utilization of Artificial Intelligence (AI) in chronic pain (CP) management.

METHODS

A comprehensive literature search was conducted using various databases, including Ovid MEDLINE, Web of Science Core Collection, IEEE Xplore, and ACM Digital Library. The search was limited to studies on AI in CP research, focusing on diagnosis, prognosis, clinical decision support, self-management, and rehabilitation. The studies were evaluated based on predefined inclusion criteria, including the reporting quality of AI algorithms used.

RESULTS

After the screening process, 60 studies were reviewed, highlighting AI's effectiveness in diagnosing and classifying CP while revealing gaps in the attention given to treatment and rehabilitation. It was found that the most commonly used algorithms in CP research were support vector machines, logistic regression and random forest classifiers. The review also pointed out that attention to CP mechanisms is negligible despite being the most effective way to treat CP.

CONCLUSION

The review concludes that to achieve more effective outcomes in CP management, future research should prioritize identifying CP mechanisms, CP management, and rehabilitation while leveraging a wider range of algorithms and architectures.

SIGNIFICANCE

This review highlights the potential of AI in improving the management of CP, which is a significant personal and economic burden affecting more than 30% of the world's population. The identified gaps and future research directions provide valuable insights to researchers and practitioners in the field, with the potential to improve healthcare utilization.

The Adaptive, Pain Sensitive, and Global Symptoms Clusters: Evidence from a Patient-Based Study

OBJECTIVES

The largest epidemiologic study conducted about painful temporomandibular disorders (pTMDs) to date identified 3 clusters of individuals with similar symptoms-adaptive, pain sensitive, and global symptoms-which hold promise as a means of personalizing pain care. Our goal was to compare the clinical and psychological characteristics that are consistent with a pTMD clinical examination among patients who are seeking care and assigned to the different clusters.

METHODS

This cross-sectional study used data from the medical records of patients attending Duke Innovative Pain Therapies between August 2017 and April 2021 who received a pTMD diagnosis (i.e., myalgia) and consented to have their data used for research. Data included orofacial and pain-related measures, dental features, and psychological measures. We used the Rapid OPPERA Algorithm to assign clusters to patients and multinomial regression to determine the likelihood (odds ratios [OR] and 95% confidence intervals [CI]) of being assigned to the pain sensitive or global symptoms cluster attributed to each measure.

RESULTS

In total, 131 patients were included in this study and assigned a cluster: adaptive (n = 54, 41.2%), pain sensitive (n = 49, 37.4%), and global symptoms (n = 28, 21.4%). The PS cluster displayed greater numbers of temporomandibular joint sites (OR, 1.29; 95% CI, 1.01 to 1.65) and masticatory (1.48; 1.19 to 1.83) and cervical (1.23; 1.09 to 1.39) muscles with pain evoked by palpation. The GS cluster displayed greater scores of pain catastrophizing (1.04; 1.01 to 1.06) and perceived stress (1.23; 1.03 to 1.46) and was more likely to report persistent pain (16.23; 1.92 to 137.1) of higher impact (1.43; 1.14 to 1.80).

CONCLUSION

Our findings support that care-seeking patients with pTMDs who are assigned to the GS cluster display a poorer psychological profile, even though those assigned to the PS cluster display more measures consistent with orofacial pain. Findings also establish the PS cluster as a group that does not display psychological comorbidities despite being hypersensitive.

KNOWLEDGE TRANSFER STATEMENT

This study informs clinicians that patients seeking care for painful temporomandibular disorders, in specific cases of myalgia, can be classified into 1 of 3 groups that display unique profiles of symptoms. Most importantly, it emphasizes the importance of examining patients with painful temporomandibular disorders in a holistic manner that includes assessing symptoms of psychological distress. Patients with greater psychological distress will likely benefit from multidisciplinary treatment strategies that may include psychological treatments.

Acceptance and Fear-Avoidance Mediate Outcomes of Interdisciplinary Pain Rehabilitation Programs at 12-Month Follow-Up: A Clinical Registry-Based Longitudinal Cohort Study from the Swedish Quality Registry for Pain Rehabilitation (SQRP)

Background

Factors that influence outcomes of interdisciplinary pain rehabilitation programs (IPRP) are poorly known. It is unclear how outcomes are influenced by pain intensity, psychological distress, and coping strategies.

Aim

This clinical registry-based longitudinal cohort study has three aims: 1) to determine the relative importance of pain intensity, psychological distress, acceptance, and fear-avoidance for changes in three outcomes of IPRP at 12-month follow-up; 2) to investigate whether the effects of pain intensity and psychological distress on the three outcomes are mediated via acceptance and fear-avoidance; and 3) to determine whether sex is a moderator.

Methods

This study uses Patient-Reported Outcome Measures (PROMs) from specialist units reporting data (2008-2016) to the Swedish Quality Registry for Pain Rehabilitation (SQRP). Adult chronic pain patients (N = 1991) answered the PROMs (background, pain, psychological distress, coping, participation, and health-related quality of life (HRQoL)). Partial Least Squares Structural Equation Modelling (PLS-SEM) was used to explore the aims.

Results

Changes in acceptance (β:0.424-0.553; all P<0.001) were the strongest predictor of the three outcomes (changes in life control, interference, and HRQoL) at 12-month follow-up. The next strongest predictor was baseline acceptance (β: 0.177-0.233; all P<0.001) and changes in fear-avoidance (β: -0.152- -0.186; all P<0.001). Baseline pain intensity and psychological distress showed weak positive associations. Their effects on the three outcomes were mediated via acceptance aspects. Sex was not a moderator.

Discussion and Conclusion

Acceptance aspects (baseline and changes) were important predictors of IPRP outcomes. Changes in fear-avoidance were also important although to a lesser degree. Some of the effects of pain intensity and psychological distress on outcomes were mediated via acceptance at baseline. Future PLS-SEM analysis of real-world IPRP should include more potential mediators (eg, catastrophizing and more facets of psychological flexibility and fear-avoidance) and the components of IPRP.

Tonic cuff pressure pain sensitivity in chronic pain patients and its relation to self-reported physical activity

OBJECTIVES

Physical inactivity is a global health concern and a significant problem among chronic pain patients. They often experience pain flare-ups when they try to increase their physical activity level. Most research on the relationship between pain sensitivity and physical activity has been on healthy participants. Data on chronic pain patients are lacking. Using cuff pressure algometry, this study investigated tonic cuff pressure pain sensitivity and its associations to self-reported physical activity and other patient-reported outcomes in chronic pain patients.

METHODS

Chronic pain patients (n=78) were compared to healthy controls (n=98). Multivariate data analysis was used to investigate the associations between tonic cuff pressure pain sensitivity, physical activity, and other patient-reported outcome measures.

RESULTS

The three most important variables for group discrimination were perceived health status (EQVAS: p(corr)=-0.85, i.e., lower in patients), depression (HADS-D: p(corr)=0.81, i.e., higher in patients), and the tonic cuff pressure pain sensitivity variable maximum pain intensity (VAS-peak-arm: p(corr)=0.75, i.e., higher in patients). In patients, the most important predictors for high VAS-peak-arm were female sex (p(corr)=-0.75), higher number of painful regions (p(corr)=0.72), higher pain intensity (p(corr)=0.55), followed by lower level of self-reported physical activity (p(corr)=-0.39). VAS-peak-arm in patients correlated negatively with self-reported physical activity (rho=-0.28, p=0.018).

CONCLUSIONS

Physical activity may be the most important patient-changeable variable correlating to pain sensitivity. This study highlights the importance of more research to further understand how increased physical activity may decrease pain sensitivity in chronic pain patients.

Serum levels of endocannabinoids and related lipids in painful vs painless diabetic neuropathy: results from the Pain in Neuropathy Study

ABSTRACT

N-arachidonoylethanolamine (also known as anandamide) and 2-arachidonoylglycerol are activators of the cannabinoid receptors. The endocannabinoid system also includes structurally and functionally related lipid mediators that do not target cannabinoid receptors, such as oleoylethanolamide, palmitoylethanolamide, and stearoylethanolamide. These bioactive lipids are involved in various physiological processes, including regulation of pain. The primary aim of the study was to analyze associations between serum levels of these lipids and pain in participants in the Pain in Neuropathy Study, an observational, cross-sectional, multicentre, research project in which diabetic patients with painless or painful neuropathy underwent deep phenotyping. Our hypothesis was that painful neuropathy would be associated with higher levels of the 5 lipids compared with painless neuropathy. Secondary aims were to analyze other patient-reported outcome measures and clinical data in relationship to lipid levels. The lipid mediators were analyzed in serum samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). Serum levels of anandamide were significantly higher in the painful group, but the effect size was small (Cohen d = 0.31). Using cluster analysis of lipid data, patients were dichotomized into a "high-level" endocannabinoid group and a "low-level" group. In the high-level group, 61% of patients had painful neuropathy, compared with 45% in the low-level group ( P = 0.039). This work is of a correlative nature only, and the relevance of these findings to the search for analgesics targeting the endocannabinoid system needs to be determined in future studies.

Expectations of treatment outcome in complex cases of patients with chronic pain: A study on the DATAPAIN cohort

BACKGROUND

A better insight in how the biopsychosocial factors influence patient outcome(s) may provide information that helps selecting the optimal pain management for a specific group.

METHODS

Categorization was made in the prospective DATAPAIN registry, in which patients with pain severity (Numeric Rating Scale [NRS]: 7-10), depression or anxiety (Hospital Anxiety and Depression Scale: > 10), and pain catastrophizing (Pain Catastrophizing Scale: > 31) were identified as complex cases. Patient outcomes; treatment satisfaction on the Patient Global Impression of Change (PGIC), pain relief (NRS), pain interference on the Brief Pain Inventory (BPI) and quality of life indicator General Perceived Health (GPH) were evaluated. Logistic regression analyzed if belonging to the complex cases showed modification in the outcome of the PGIC and GPH. Linear regression was observed if complex cases differed in average reduction in pain relief and interference compared to non-complex cases.

RESULTS

1637 patients were included, of which 345 (21.08%) were considered complex cases. The changes in scores of pain relief and BPI active subscale were not significantly different between groups. The BPI affective subscale had a different change in score (-0.509; p: 0.002). The complex cases had an odds ratio (OR) of 0.59 (95% confidence interval [CI]: 0.36-0.77) on treatment satisfaction compared to non-complex cases, and an OR of 0.28 (95% CI: 0.11-0.56) on the GPH.

CONCLUSION

When treating patients with complex cases, desired treatment outcome(s) should be recognized by specialists and patients, as these may be less likely to occur.

The role of evolving concepts and new technologies and approaches in advancing pain research, management, and education since the establishment of the International Association for the Study of Pain

ABSTRACT

The decades since the inauguration of the International Association for the Study of Pain have witnessed major advances in scientific concepts (such as the biopsychosocial model and chronic primary pain as a disease in its own right) and in new technologies and approaches (from molecular biology to brain imaging) that have inspired innovations in pain research. These have guided progress in pain management and education about pain for healthcare professionals, the general public, and administrative agencies.

Unsupervised learning for prognostic validity in patients with chronic pain in transdisciplinary pain care

Chronic pain is not a singular disorder and presents in various forms and phenotypes. Here we show data from a cohort of patients seeking treatment in a transdisciplinary pain clinic. Patients completed a multidimensional patient-reported battery as part of routine initial evaluation at baseline and at each of the four subsequent visits over 1-year follow-up (0, 1, 3, 6, 12 months). The goal of this work was to use unsupervised modeling approach to identify whether patients with chronic pain undergoing transdisciplinary intensive rehabilitation treatment: (1) can be derived based upon self-reported outcome measures at baseline (or before treatment initiation), (2) are clinically validated based on their clinical diagnosis and medication use, and (3) differ in treatment trajectories over 1 year of transdisciplinary treatment. We applied unsupervised clustering on baseline outcomes using nine patient-reported symptoms and examined treatment trajectories. The three-cluster solution was internally validated. Psychiatric diagnosis, chronic back pain-related disability and symptoms severity determined cluster assignment and treatment prognosis. Conversely, clinical pain severity had lesser effect. Furthermore, clusters showed stability over time despite symptoms improvement. The accurate and meaningful subgrouping of the underlying chronic pain phenotypes would greatly enhance treatment and provide personalized and effective pain management.

Effects of interdisciplinary pain rehabilitation programs on neuropathic and non-neuropathic chronic pain conditions - a registry-based cohort study from Swedish Quality Registry for Pain Rehabilitation (SQRP)

BACKGROUND AND AIM

Neuropathic pain arises as a direct consequence of a lesion or disease affecting the somatosensory system. Pharmacological treatments for neuropathic pain often fail despite following guidelines. Interdisciplinary Pain Rehabilitation Programs (IPRP) are an effective intervention for chronic pain conditions. Little research has investigated whether IPRP can benefit patients with chronic neuropathic pain compared to other chronic pain conditions. This study assesses the real-world effects of IPRP on patients with chronic neuropathic pain compared to non-neuropathic patients using Patient-Reported Outcome Measures (PROMs) available in the Swedish Quality Registry for Pain Rehabilitation (SQRP).

METHODS

A neuropathic group of patients (n = 1,654) were identified in two steps. This group was compared to a non-neuropathic group (n = 14,355) composed of common diagnoses (low back pain, fibromyalgia, whiplash associated disorders, and Ehlers-Danlos Syndrome) in relation to background variables, three overall outcome variables, and mandatory outcome variables (pain intensity, psychological distress symptoms, activity/participation aspects and health-related quality of life variables). Of these patients 43-44% participated in IPRP.

RESULTS

At assessment, the neuropathic group reported significantly (with small effect sizes (ES)) more physician visits the previous year, older age, shorter pain durations, and less spatial extent of the pain (moderate ES). Moreover, for the 22 mandatory outcome variables, we found only clinically insignificant differences according to ESs between the groups. For patients participating in IPRP, the neuropathic group displayed equal or in some cases slightly superior results compared to the non-neuropathic group.

DISCUSSION AND CONCLUSION

After assessing the real-world effects of IPRP, this large study found that neuropathic pain patients can benefit from the IPRP intervention. Both registry studies and RCTs are needed to better understand which patients with neuropathic pain are most suitable for IPRP and to what extent special considerations need to be made for these patients within the framework of IPRP.

Fear network and pain extent: Interplays among psychological constructs related to the fear-avoidance model

OBJECTIVE

Psychological constructs related to the fear-avoidance model such as fear of movement, pain catastrophizing, and affective distress have been found to be inter-related among patients with chronic pain. However, relationships of these constructs have mostly been examined using regression-based analyses. This cross-sectional study employs a novel analytical approach, network analysis, to illustrate the complex interplays among these variables as well as pain intensity and pain interference.

METHODS

This study utilized the Swedish Quality Registry for Pain Rehabilitation, including data from 10,436 participants (76.0% women; M_age = 45.0 years). Networks were analyzed separately for patients with different pain extents (i.e., numbers of pain locations) as the interplays may differ qualitatively depending on pain extent.

RESULTS

We found that patients with a larger pain extent showed a worse clinical presentation (i.e., more depression and anxiety, increased fear of movement and pain interference), and their network differed from the patients with a smaller number of pain extent in terms of how strongly key variables were interconnected. In all network models, pain interference and catastrophizing showed consistently influential roles.

CONCLUSION

Our findings highlight the interactive nature of psychological aspects of pain and how interrelated associations differ depending on pain extent. Findings are discussed based on ideas on how both fear and pain become overgeneralized.

Pain intensity and psychological distress show different associations with interference and lack of life control: A clinical registry-based cohort study of >40,000 chronic pain patients from SQRP

Background

Both chronic pain and depressive and/or anxiety symptoms are associated with negative impacts on daily living, including interference and lack of life control. However, little is known about how pain and psychological distress affect these impacts.

Aim

The first aim was to assess how pain intensity, psychological distress, and social support interact with interference and lack of life control. A second aim was to investigate whether the strength of these relationships is moderated by the presence or absence of depression and/or anxiety.

Subjects and methods

Patient-Reported Outcome Measures (PROMs), which are available in the Swedish Quality Registry for Pain Rehabilitation (SQRP), were retrieved for patients with chronic pain (N = 40,184). A theoretical model with the constructs/latent variables pain intensity, psychological distress, interference, lack of life control, and social support was proposed and analyzed using Partial Least Squares Structural Equation Modelling (PLS-SEM). Indicators for these constructs were identified from the PROMs of the SQRP. Two models of the total cohort, which differed with respect to the causal relationship between pain intensity and psychological distress, were investigated. The moderating effects of anxiety and/or depression were also analyzed.

Results

Relatively low correlation and explanatory power (R ²= 0.16) were found for the pain intensity-psychological distress relationship. Pain intensity had a stronger effect on interference than on lack of life control. The reverse was found for psychological distress - i.e., psychological distress seemed to have a higher negative influence on function than on interference. The underlying assumption of the causal relationship between pain intensity and psychological distress determined how strong pain intensity and psychological distress influenced interference and lack of life control. Social support showed very similar absolute significant correlations with interference and lack of life control. Interference and lack of life control showed relatively weak associations. The psychological distress level was a moderating factor for several of the paths investigated.

Discussion and conclusion

A clinical treatment consequence of the low correlation between pain intensity and psychological distress may be that clinically treating one may not reduce the effect of the other. The relative importance of pain intensity and psychological distress on interference and lack of life control depends on the underlying assumption concerning the pain intensity-psychological distress relationship. Interference and lack of life control showed relatively weak associations, underscoring the need to clinically assess them separately. Social support influenced both impact constructs investigated. The cohort display heterogeneity and thus presence of definite signs of anxiety and/or depression or not was a moderating factor for several of the associations (paths) investigated. The results are important both for the assessments and the design of treatments for patients with chronic pain.

Pain Empathy and Its Association with the Clinical Pain in Knee Osteoarthritis Patients

Objective

Knee osteoarthritis (KOA) is a painful chronic disorder. Evidence has shown that a history of chronic pain plays an important role in shaping empathy. Empathy, a valuable indicator of social functioning that refers to an individual's ability to share the experiences of others, however, has been overlooked in KOA patients. This study aimed to investigate empathy and its association with clinical pain in KOA patients.

Methods

KOA patients (n=47) and healthy controls (HCs, n=44) completed two empathy-for-pain tasks: a pain judgment task in which participants judged whether a person in an image felt pain or not, and a pain rating task in which they estimated pain intensity for themselves and others. The Interpersonal Reactivity Index was used to measure participants' trait empathy, and clinical severity and psychological factors were assessed using relevant instruments.

Results

Compared to HCs, KOA patients showed higher accuracy when judging pain and non-pain images and reported overall higher pain intensity when rating for themselves and others. KOA patients also showed greater personal distress than HCs in terms of their self-reported empathy. Moreover, pain catastrophizing particularly mediated the relationship between pain severity and pain ratings for others, and depression, anxiety, and pain catastrophizing all mediated the association between pain severity and empathy-induced personal distress.

Conclusion

These findings suggest that patients with KOA have increased empathy, demonstrated by elevated sensitivity to pain-related scenes and intense emotional responses.

The treatment lottery of chronic back pain? A case series at a multidisciplinary pain centre

OBJECTIVES

Despite the number of people affected by chronic back pain, and the many available treatment options, even the best modalities provide limited pain reduction on a group level, often without simultaneous improvements in functioning or health-related quality of life. The objective was to provide an overview of the treatment of chronic back pain in clinical practice at a multidisciplinary pain centre, and to study patient and pain characteristics in different treatment groups.

METHODS

104 chronic back pain patients (primary ICD-10-SE-diagnosis M53.0-M54.9 excluding M54.1 and M54.3), referred to the Pain and Rehabilitation Centre, University Hospital, Linköping in 2015, were studied using data from the Swedish Quality Registry for Pain Rehabilitation, self-reported medication data, and a retrospective medical record review.

RESULTS

The following treatment groups were identified: rehabilitation (n=21), analgesics (n=33), invasive intervention (n=14), and no treatment (n=35). Significant differences between groups were found with regards to age, sick leave, education level, persisting pain duration, punishing responses by significant other, previous invasive intervention, receiving sub-clinic, physician speciality and referring care level.

CONCLUSIONS

Overall, patient demographics were associated with treatment strategy to a higher degree than patient-reported outcome measures. Moreover, physician speciality and organisational factors seemed to play a role in treatment choice.

Profiles of Risk and Resilience in Chronic Pain: Loneliness, Social Support, Mindfulness, and Optimism Coming out of the First Pandemic Year

OBJECTIVE

Individuals experience chronic pain differently, not only because of different clinical diagnoses, but also because of differing degrees of influence from biopsychosocial pain modulators. We aimed to cluster patients with chronic pain into distinct subgroups based on psychosocial characteristics and pain intensity, and we subsequently examined group differences in pain-related interference approximately 1 year later.

METHODS

In this observational, longitudinal study, patients with chronic pain (n = 94) completed validated assessments of psychosocial characteristics and pain intensity at the beginning of COVID-19-related social distancing (April to June 2020). One year later (May to June 2021), patients completed a follow-up survey with assessments of pain interference, loneliness, social support, mindfulness, and optimism.

RESULTS

A cluster analysis, using psychosocial factors and pain intensity, empirically produced three patient groups: 1) psychosocial predominant (PSP), characterized by high psychosocial distress and average pain intensity; 2) pain intensity predominant (PIP), characterized by average psychosocial distress and high pain intensity; and 3) less elevated symptoms (LES), characterized by low psychosocial distress and low pain intensity. At the 1-year follow-up, patients in the PSP and PIP clusters suffered greater pain interference than patients in the LES cluster, while patients in the PSP cluster also reported greater loneliness and lower mindfulness and optimism.

CONCLUSIONS

An empirical psychosocial-based clustering of patients identified three distinct groups that differed in pain interference. Patients with high psychosocial modulation of pain at the onset of social distancing (the PSP cluster) suffered not only greater pain interference but also greater loneliness and lower levels of mindfulness and optimism, which suggests some potential behavioral targets for this group in the future.

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

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

Chronic back pain sub-grouped via psychosocial, brain and physical factors using machine learning

Chronic back pain (CBP) is heterogenous and identifying sub-groups could improve clinical decision making. Machine learning can build upon prior sub-grouping approaches by using a data-driven approach to overcome clinician subjectivity, however, only binary classification of pain versus no-pain has been attempted to date. In our cross-sectional study, age- and sex-matched participants with CBP (n = 4156) and pain-free controls (n = 14,927) from the UkBioBank were included. We included variables of body mass index, depression, loneliness/social isolation, grip strength, brain grey matter volumes and functional connectivity. We used fuzzy c-means clustering to derive CBP sub-groups and Support Vector Machine (SVM), Naïve Bayes, k-Nearest Neighbour (kNN) and Random Forest classifiers to determine classification accuracy. We showed that two variables (loneliness/social isolation and depression) and five clusters were optimal for creating sub-groups of CBP individuals. Classification accuracy was greater than 95% for when CBP sub-groups were assessed only, while misclassification in CBP sub-groups increased to 35-53% across classifiers when pain-free controls were added. We showed that individuals with CBP could sub-grouped and accurately classified. Future research should optimise variables by including specific spinal, psychosocial and nervous system measures associated with CBP to create more robust sub-groups that are discernible from pain-free controls.

Hepatocyte growth factor, colony-stimulating factor 1, CD40, and 11 other inflammation-related proteins are associated with pain in diabetic neuropathy: exploration and replication serum data from the Pain in Neuropathy Study

ABSTRACT

One in 5 patients with diabetes suffers from chronic pain with neuropathic characteristics, but the pathophysiological mechanisms underlying the development of neuropathic pain in patients with diabetic distal symmetrical polyneuropathy (DSP) are poorly understood. Systemic low-grade inflammation has been implicated, but there is still a considerable knowledge gap concerning its scope and meaning in this context. The aim of the study was to establish the broad inflammatory signature of painful diabetic DSP in serum samples from the Pain in Neuropathy Study, an observational cross-sectional multicentre study in which participants underwent deep phenotyping. In the present two cohorts exploration-replication study (180 participants in each cohort), serum samples from Pain in Neuropathy Study participants were analyzed with the Olink INFLAMMATION panel (Olink Bioscience, Uppsala, Sweden) that enables the simultaneous measurement of 92 inflammation-related proteins (mainly cytokines, chemokines, and growth factors). In both the exploration and the replication cohort, we identified a high-inflammation subgroup where 14 inflammation-related proteins in particular were associated with more neuropathy and higher pain intensity. The top 3 proteins were hepatocyte growth factor, colony-stimulating factor 1, and CD40 in both cohorts. In the exploratory cohort, additional clinical data were available, showing an association of inflammation with insomnia and self-reported psychological distress. Hence, this cross-sectional exploration-replication study seems to confirm that low-grade systemic inflammation is related to the severity of neuropathy and neuropathic pain in a subgroup of patients with diabetic DSP. The pathophysiological relevance of these proteins for the development of neuropathic pain in patients with diabetic DSP must be explored in more depth in future studies.

Facing Invalidation: A Further Challenge when Living with Chronic Widespread Pain

OBJECTIVE

The concept of "invalidation" refers to the patient's perception that the social environment does not recognize their medical condition. This study explores and describes invalidation experiences among Swedish patients with chronic widespread pain with regard to sociodemographic and pain characteristics, impact of pain, self-reported health, and symptoms of anxiety and depressive.

METHODS

A cross-sectional design using questionnaires, including sociodemographic and pain variables, the Illness Invalidation Inventory (Likert scale items regarding 5 sources), the Hospital Anxiety and Depression Scale, and the Short-Form General Health Survey. Descriptive and univariate analyses were applied.

RESULTS

Of the 152 respondents, 91% were women. Swedish patients with chronic widespread pain experienced invalidation to a large extent from all sources. The highest scores for invalidation were reported from contacts with social services (68%), and the lowest from spouses (30%). Being younger (p < 0.006), having periodic pain (p = 0.011), and having had more frequent visits to a doctor in the previous year (p = 0.007) were characteristics associated with higher invalidation scores. Experiences of invalidation were associated with worse selfreported mental health scores (r = -0.29 to -0.46).

CONCLUSION

Since patients with chronic widespread pain frequently experience invalidation from the social environment, this further challenge in daily life must be taken into consideration in pain management within multimodal pain rehabilitation.

Classifying chronic pain using multidimensional pain-agnostic symptom assessments and clustering analysis

Chronic pain conditions present in various forms, yet all feature symptomatic impairments in physical, mental, and social domains. Rather than assessing symptoms as manifestations of illness, we used them to develop a chronic pain classification system. A cohort of real-world treatment-seeking patients completed a multidimensional patient-reported registry as part of a routine initial evaluation in a multidisciplinary academic pain clinic. We applied hierarchical clustering on a training subset of 11,448 patients using nine pain-agnostic symptoms. We then validated a three-cluster solution reflecting a graded scale of severity across all symptoms and eight independent pain-specific measures in additional subsets of 3817 and 1273 patients. Negative affect–related factors were key determinants of cluster assignment. The smallest subset included follow-up assessments that were predicted by baseline cluster assignment. Findings provide a cost-effective classification system that promises to improve clinical care and alleviate suffering by providing putative markers for personalized diagnosis and prognosis.

Hierarchical clustering by patient-reported pain distribution alone identifies distinct chronic pain subgroups differing by pain intensity, quality, and clinical outcomes

Background

In clinical practice, the bodily distribution of chronic pain is often used in conjunction with other signs and symptoms to support a diagnosis or treatment plan. For example, the diagnosis of fibromyalgia involves tallying the areas of pain that a patient reports using a drawn body map. It remains unclear whether patterns of pain distribution independently inform aspects of the pain experience and influence patient outcomes. The objective of the current study was to evaluate the clinical relevance of patterns of pain distribution using an algorithmic approach agnostic to diagnosis or patient-reported facets of the pain experience.

Methods and findings

A large cohort of patients (N = 21,658) completed pain body maps and a multi-dimensional pain assessment. Using hierarchical clustering of patients by body map selection alone, nine distinct subgroups emerged with different patterns of body region selection. Clinician review of cluster body maps recapitulated some clinically-relevant patterns of pain distribution, such as low back pain with radiation below the knee and widespread pain, as well as some unique patterns. Demographic and medical characteristics, pain intensity, pain impact, and neuropathic pain quality all varied significantly across cluster subgroups. Multivariate modeling demonstrated that cluster membership independently predicted pain intensity and neuropathic pain quality. In a subset of patients who completed 3-month follow-up questionnaires (N = 7,138), cluster membership independently predicted the likelihood of improvement in pain, physical function, and a positive overall impression of change related to multidisciplinary pain care.

Conclusions

This study reports a novel method of grouping patients by pain distribution using an algorithmic approach. Pain distribution subgroup was significantly associated with differences in pain intensity, impact, and clinically relevant outcomes. In the future, algorithmic clustering by pain distribution may be an important facet in chronic pain biosignatures developed for the personalization of pain management.

Improvement in pain interference and function by an allied health pain management program: Results of a randomized trial

BACKGROUND

Chronic pain is a significant health problem worldwide and requires a biopsychosocial treatment approach. Access to traditional pain medicine specialist services is limited and innovative treatment models are required to support patients in tertiary care. The study evaluated the clinical effectiveness and safety of the Treatment Access Pathway (TAP), an allied health expanded scope model of care which included innovative group assessment and collaboration with patients to create individualized treatment plans.

METHODS

One hundred and eighty-one patients referred to a tertiary level chronic pain service were randomly allocated to either the TAP or the waitlist study groups. Primary (pain interference) and secondary outcome measures were collected at recruitment and again at 6 months. Per-protocol analyses were utilized due to high participant attrition (46% across groups).

RESULTS

The TAP group reported greater reductions in pain interference at 6 months than waitlist group (0.9, 95% CI: 0.2-1.6), with more than half of the TAP group (52%) reporting clinically significant improvement. In addition, statistically significant differences between the TAP and waitlist groups were observed for objective measurements of walking endurance (5.4 m, 95% CI: 1.7-9.1); and global impressions of change (1.4 unit decrease, 95% CI: 1-1.9). Nil adverse events were recorded.

CONCLUSIONS

The study suggests that an expanded scope allied health model of care prioritizing patient choice and group-based interventions provides modest benefits for tertiary-referral chronic pain patients. TAP warrants further investigation as a potentially viable alternative for tertiary healthcare where traditional pain services are unavailable or have long waiting lists.

SIGNIFICANCE

The study tests effectiveness and safety of an expanded scope allied health-led chronic pain program. Despite a high attrition rate, the study showed reduced pain interference and increased physical function in those who completed the protocol. The results are promising and support introduction of this model as an adjunct to existing traditional chronic pain models of care, with a particular focus on improving participant retention in the program. Additionally, the model of care can be used as a standalone chronic pain model of care where no other pain management resources are available. The study was registered on ANZCTR (Trial ID: ACTRN12617001284358).

Establishing Central Sensitization-Related Symptom Severity Subgroups: A Multicountry Study Using the Central Sensitization Inventory

OBJECTIVES

The goal of this study was to identify central sensitization-related symptom severity subgroups in a large multicountry sample composed of patients with chronic pain and pain-free individuals using the Central Sensitization Inventory (CSI).

METHODS

A large, pooled international (N = 8 countries) sample of chronic pain patients plus healthy subjects (total N = 2,620) was randomly divided into two subsamples for cross-validation purposes. First, a hierarchical cluster analysis (HCA) was performed using CSI item-level data as clustering variables (test sample; N = 1,312). Second, a latent profile analysis (LPA) was conducted to confirm the optimal number of CSI clusters (validation sample; N = 1,308). Finally, to promote implementation in real-world clinical practice, we built a free online Central Sensitization Inventory Symptom Severity Calculator.

RESULTS

In both HCA (N = 1,219 valid cases) and LPA (N = 1,245 valid cases) analyses, a three-cluster and three-profile solution, respectively, emerged as the most statistically optimal and clinically meaningful. Clusters were labeled as follows: (i) Low Level of CS-Related Symptom Severity, (ii) Medium Level of CS-Related Symptom Severity, and (iii) High Level of CS-Related Symptom Severity.

CONCLUSIONS

Our results indicated that a three-cluster solution clearly captured the heterogeneity of the CSI data. The calculator might provide an efficient way of classifying subjects into the cluster groups. Future studies should analyze the extent to which the CSI cluster classification correlates with other patient-reported and objective signs and symptoms of CS in patients with chronic pain, their associations with clinical outcomes, health-related costs, biomarkers, (etc.), and responsiveness to treatment.

Phenotypic profile clustering pragmatically identifies diagnostically and mechanistically informative subgroups of chronic pain patients

ABSTRACT

Traditional classification and prognostic approaches for chronic pain conditions focus primarily on anatomically based clinical characteristics not based on underlying biopsychosocial factors contributing to perception of clinical pain and future pain trajectories. Using a supervised clustering approach in a cohort of temporomandibular disorder cases and controls from the Orofacial Pain: Prospective Evaluation and Risk Assessment study, we recently developed and validated a rapid algorithm (ROPA) to pragmatically classify chronic pain patients into 3 groups that differed in clinical pain report, biopsychosocial profiles, functional limitations, and comorbid conditions. The present aim was to examine the generalizability of this clustering procedure in 2 additional cohorts: a cohort of patients with chronic overlapping pain conditions (Complex Persistent Pain Conditions study) and a real-world clinical population of patients seeking treatment at duke innovative pain therapies. In each cohort, we applied a ROPA for cluster prediction, which requires only 4 input variables: pressure pain threshold and anxiety, depression, and somatization scales. In both complex persistent pain condition and duke innovative pain therapies, we distinguished 3 clusters, including one with more severe clinical characteristics and psychological distress. We observed strong concordance with observed cluster solutions, indicating the ROPA method allows for reliable subtyping of clinical populations with minimal patient burden. The ROPA clustering algorithm represents a rapid and valid stratification tool independent of anatomic diagnosis. ROPA holds promise in classifying patients based on pathophysiological mechanisms rather than structural or anatomical diagnoses. As such, this method of classifying patients will facilitate personalized pain medicine for patients with chronic pain.

Cluster analysis of Canadian Armed Forces veterans living with chronic pain: Life After Service Studies 2016

Objective: This study explored the heterogeneity of Canadian Armed Forces veterans living with chronic pain to inform service needs planning and research using cluster analysis. Design: We used a national cross-sectional Statistics Canada population survey. Participants: Participants included 2754 Canadian Armed Forces (CAF) Regular Force veterans released from service between 1998 and 2015 and surveyed in 2016. Methods: We used cluster analysis of veterans with chronic pain based on pain severity, mental health, and activity limitation characteristics. We compared clusters for sociodemographic, health, and service utilization characteristics. Results: Of 2754 veterans, 1126 (41%) reported chronic pain. Veterans in cluster I (47%) rarely had severe pain (2%) or severe mental health problems (8%), and none had severe activity limitations. Veterans in cluster II (26%) more often than veterans in cluster I but less often than veterans in cluster III endorsed severe pain (27%) and severe mental health problems (22%) and were most likely to report severe activity limitation (91%). Veterans in cluster III (27%) were most likely to report severe pain (36%) and severe mental health problems (96%), and a majority reported severe activity limitations (72%). There was evidence of considerable heterogeneity among individuals in terms of socioeconomic characteristics, pain characteristics, mental and physical health status, activity limitations, social integration, and service utilization indicators. Conclusions: About half of Canadian veterans living with chronic pain infrequently endorse severe pain or serious mental health issues without severe activity limitations. The other half had more complex characteristics. The heterogeneity of CAF veterans with chronic pain emphasizes the need for support systems that can address variability of needs.

The Development of Mindful-Based Dance Movement Therapy Intervention for Chronic Pain: A Pilot Study With Chronic Headache Patients

Chronic pain is of significant global concern. There is growing evidence that body–mind therapies and psychological approaches can contribute toward changing chronic pain perceptions. This is the first model described in the literature that combines a mindfulness-based approach with dance movement therapy and explores the potential psychological and pain-related changes for this client population. In this paper, the results from the pilot study are presented involving patients with chronic headache recruited in an outpatient rehabilitation setting.

Methods: In this pilot study, 29 patients (n = 29) with chronic headache were randomized to either the Mindful-Based Dance Movement Therapy (MBDMT) group or the waiting list control group (treatment as usual, TAU). The MBDMT group was offered 10 sessions in a clinical outpatient rehabilitation setting for 5 weeks. Data were collected pre- and post-intervention and 16 weeks after the intervention was finished. The Hospital Anxiety and Depression Scale (HADS), Patient Health Questionnaire−9 (PHQ-9), Five Facet Mindfulness Questionnaire (FFMQ), and Numeric Rating Scale (NRS) were used as outcome measures.

Results: The working model of MBDMT identifies nine therapeutic mechanisms (safe therapeutic environment, mindfulness skills, body awareness, relaxation/releasing, distancing and staying with discomfort, meaning making, self-regulation, acceptance and integration, creative process). Per-protocol analysis reveals statistically significant reduction of pain intensity and depression scores in favor of the MBDMT group, and these improvements were maintained in the follow-up assessment.

Conclusions: The results suggest that MBDMT is a feasible and promising therapy approach for chronic pain patients. The pilot study offered sufficient information and preliminary results in the desirable direction to enable the researchers to move to a randomized controlled trial (RCT) stage in order to establish the efficacy of the intervention.

Clinical Trial Registration: The study was registered in the www.researchregistry.com, registry (5483).

Outcomes of Interdisciplinary Pain Rehabilitation Across Subgroups of the Multidimensional Pain Inventory - A Study From the Swedish Quality Registry for Pain Rehabilitation

INTRODUCTION

The Multidimensional Pain Inventory (MPI) is frequently used in the assessment of chronic pain. Three subgroups have been derived from MPI: adaptive coper (AC), dysfunctional (DYS), and interpersonally distressed (ID). The primary aim of this study was to examine whether outcome of Interdisciplinary Multimodal Pain Rehabilitation Programs (IMMRPs) differed across the MPI subgroups.

METHODS

Patients with chronic pain (N = 34,513), included in the Swedish Quality Registry for Pain Rehabilitation, were classified into MPI subgroups and a subset that participated in IMMRPs (N = 13,419) was used to examine overall treatment outcomes using a previously established Multivariate Improvement Score (MIS) and 2 retrospective patient-evaluated benefits from treatment.

RESULTS

The subgroups differed on sociodemographic characteristics, pain duration, and spatial spreading of pain. DYS and ID had the best overall outcomes to MIS. AC had the best outcomes according to the 2 retrospective items. Transition into other subgroups following IMMRP was common and most prominent in DYS and least prominent in AC.

CONCLUSION

The validity of the MPI subgroups was partially confirmed. DYS and ID had the most severe clinical presentations at baseline and showed most improvement following IMMRP, but overall severity in DYS and ID at post-treatment was still higher than in the AC group. Future studies should examine how processes captured by MPI interact with neurobiological, medical, sociodemographic, and adaptation/coping factors and how these interactions impact severity of chronic pain and treatment outcome.

Spreading of Pain in Patients with Chronic Pain is Related to Pain Duration and Clinical Presentation and Weakly Associated with Outcomes of Interdisciplinary Pain Rehabilitation: A Cohort Study from the Swedish Quality Registry for Pain Rehabilitation (SQRP)

Introduction

The extent to which pain is distributed across the body (spreading of pain) differs largely among patients with chronic pain conditions and widespread pain has been linked to poor quality of life and work disability. A longer duration of pain is expected to be associated with more widespread pain, but studies are surprisingly scarce. Whether spreading of pain is associated with clinical presentation and treatment outcome in patients seen in interdisciplinary multimodal pain rehabilitation programs (IMMRPs) is unclear. The association between spreading of pain and (1) pain duration (2) clinical presentation (eg, pain intensity, pain-related cognitions, psychological distress, activity/participation aspects and quality of life) and (3) treatment outcome were examined.

Methods

Data from patients included in the Swedish Quality Registry for Pain Rehabilitation were used (n=39,916). A subset of patients that participated in IMMRPs (n=14,666) was used to examine whether spreading of pain at baseline predicted treatment outcome. Spreading of pain was registered using 36 predefined anatomical areas which were summarized and divided into four categories: 1–6 regions with pain (20.6% of patients), 7–12 regions (26.8%), 13–18 regions (22.0%) and 19–36 regions (30.6%).

Results

More widespread pain was associated with a longer pain duration and a more severe clinical picture at baseline with the strongest associations emerging in relation to health and pain aspects (pain intensity, pain interference and pain duration). Widespread pain was associated with a poorer overall treatment outcome following IMMRPs at both posttreatment and at a 12-month follow-up, but effect sizes were small.

Discussion

Spreading of pain is an indicator of the duration and severity of chronic pain and to a limited extent to outcomes of IMMRP. Longer pain duration in those with more widespread pain supports the concept of early intervention as clinically important and implies a need to develop and improve rehabilitation for patients with chronic widespread pain.

Pain management in patients undergoing radiation therapy for head and neck cancer - a descriptive study

OBJECTIVES

Patients with head and neck cancer (HNC) experience serious pain related to tumour, surgery, chemotherapy, and radiotherapy treatment (RT). Oral mucositis, a painful complication of RT, may require opioid analgesics to control pain.This longitudinal study, during RT but also four weeks post-RT, examines the relationships between oral mucositis, pain, and opioid doses in in HNC patients. The aim was to evaluate the clinical effectiveness of an opioid treatment strategy.

METHODS

Sixty-three patients with HNC undergoing radiotherapy answered self-reported questionnaires on pain intensity on a 0-10 numerical rating scale (NRS) three times a week. Oral mucositis signs were evaluated using the WHO mucositis index score, ranging from 0 (normal) to 4 (severe), and pharmacological treatment with opioids was registered prospectively once a week. All data were related to given radiation dose, and all outcome measures at each time point therefore relate to the same radiation dose (i.e., not to when the patient was included in the study).

RESULTS

Opioids were used by 78% of the patients. Most of the patients experienced only mild pain (NRS 0-4), although the majority developed mucositis grade 2-4 according to WHO mucositis index. Function-related pain intensity and opioid doses were highest during the sixth week of RT, with 3.67 (0-9) in NRS and 84 (0-430) mg oral morphine equivalents per day (median, range). At that same time point, significant positive correlations were found between the grade of mucositis and pain intensities. Patients with mucositis grade 2-4 were investigated further; in this subgroup, we found that opioid doses did not differ between patients with mild pain and patients with moderate to severe pain. Our multivariate data analysis defined a cluster of patients characterized by the presence of mucositis, cancer site in pharynx, concomitant chemotherapy, and the absence of surgery.

CONCLUSIONS

In HNC patients who were followed closely by pain care personnel during and after RT, pain was often satisfactorily alleviated with a structured use of opioids, including stepwise increases of fentanyl patches and oral morphine as needed. However, some patients with oral mucositis grade 2-4 experienced severe pain. Strong opioids, i.e. the third step of the WHO pain ladder, remain the mainstay of analgesic therapy in treating moderate to severe cancer-related pain, including patients with HNC. This real-life study indicates that RT-related pain is not a fatality. A proactive stance, monitoring these patients closely and regularly, is probably crucial in order to achieve good treatment results. Further studies are needed to develop better pain treatment strategies for those patients who develop severe oral mucositis-related pain despite intensive opioid treatment.

Subgroups of Pediatric Patients With Functional Abdominal Pain: Replication, Parental Characteristics, and Health Service Use

OBJECTIVES

Prior work in a cohort of youth with functional abdominal pain (FAP) identified patient subgroups (High Pain Dysfunctional, High Pain Adaptive, Low Pain Adaptive) that predicted differences in the course of FAP from childhood into young adulthood. We aimed to replicate these subgroups in a new sample of adolescents with FAP using the original classification algorithm and to extend subgroup characteristics to include parental characteristics and health service use.

METHODS

Adolescents (n=278; ages 11 to 17 y, 66% females) presenting to a gastroenterology clinic for abdominal pain, and their parents (92% mothers) completed self-report measures; adolescents also completed a 7-day pain diary.

RESULTS

The replicated patient subgroups exhibited distress and impairment similar to subgroups in the original sample. Moreover, in novel findings, the High Pain Dysfunctional subgroup differed from other subgroups by the predominance of mother-daughter dyads jointly characterized by high levels of anxiety, depressive symptoms, pain behavior, and pain catastrophizing. The High Pain Dysfunctional subgroup used more health care services than Low Pain Adaptive but did not differ from High Pain Adaptive.

DISCUSSION

Findings replicate and extend the original FAP classification and suggest that the subgroups have unique patient and parent features that may reflect distinct illness mechanisms requiring different treatments.

Influences of Sex, Education, and Country of Birth on Clinical Presentations and Overall Outcomes of Interdisciplinary Pain Rehabilitation in Chronic Pain Patients: A Cohort Study from the Swedish Quality Registry for Pain Rehabilitation (SQRP)

This study investigates the effects of sex, education, and country of birth on clinical presentations and outcomes of interdisciplinary multimodal pain rehabilitation programs (IMMRPs). A multivariate improvement score (MIS) and two retrospective estimations of changes in pain and ability to handle life situations were used as the three overall outcomes of IMMRPs. The study population consisted of chronic pain patients within specialist care in the Swedish Quality Registry for Pain Rehabilitation (SQRP) between 2008 and 2016 at baseline (n = 39,916), and for the subset participating in IMMRPs (n = 14,666). A cluster analysis based on sex, education, and country of origin revealed significant differences in the following aspects: best baseline clinical situation was for European women with university educations and the worst baseline clinical situation was for all patients born outside Europe of both sexes and different educations (i.e., moderate-large effect sizes). In addition, European women with university educations also had the most favorable overall outcomes in response to IMMRPs (small effect sizes). These results raise important questions concerning fairness and equality and need to be considered when optimizing assessments and content and delivery of IMMRPs for patients with chronic pain.

Pain Catastrophizing in Older Adults with Chronic Pain: The Mediator Effect of Mood Using a Path Analysis Approach

Cognitive models of pain propose that catastrophic thinking is negatively associated with chronic pain. However, pain catastrophizing is a complex phenomenon requiring a multivariate examination. This study estimates the effects of mood variables (anxiety and depression) on pain catastrophizing in older adults with chronic pain. A postal survey addressing pain aspects was sent to 6611 people ≥ 65 years old living in south-eastern Sweden. Pain catastrophizing was measured using the pain catastrophizing scale. Anxiety and depression were assessed using two subscales of the general well-being schedule. Data were analysed using a path analysis approach. A total of 2790 respondents (76.2 ± 7.4 years old) reported chronic pain (≥three months). The mediation model accounted for 16.3% of anxiety, 17.1% of depression, and 30.9% of pain catastrophizing variances. Pain intensity, insomnia, number of comorbidities, and lifestyle factors (smoking, alcohol consumption, and weight) significantly affected both pain catastrophizing and mood. Anxiety (standardized path coefficient (b_std) = 0.324, p < 0.001) in comparison to depression (b_std = 0.125, p < 0.001) had a greater effect on pain catastrophizing. Mood mediated the relationship between pain catastrophizing and pain-related factors accounting for lifestyle and sociodemographic factors.

A Step Towards a Better Understanding of Pain Phenotypes: Latent Class Analysis in Chronic Pain Patients Receiving Multimodal Inpatient Treatment

Purpose

The number of non-responders to treatment among patients with chronic pain (CP) is high, although intensive multimodal treatment is broadly accessible. One reason is the large variability in manifestations of CP. To facilitate the development of tailored treatment approaches, phenotypes of CP must be identified. In this study, we aim to identify subgroups in patients with CP based on several aspects of self-reported health.

Patients and Methods

A latent class analysis (LCA) was carried out in retrospective data from 411 patients with CP of different origins. All patients experienced severe physical and psychosocial consequences and were therefore undergoing multimodal inpatient pain treatment. Self-reported measures of pain (visual analogue scales for pain intensity, frequency, and impairment; Pain Perception Scale), emotional distress (Patient Health Questionnaire, PHQ-9; Generalized Anxiety Disorder Scale, GAD-7) and physical health (Short Form Health Survey; SF-8) were collected immediately after admission and before discharge. Instruments assessed at admission were used as input to the LCA. Resulting classes were compared in terms of patient characteristics and treatment outcome.

Results

A model with four latent classes demonstrated the best model fit and interpretability. Classes 1 to 4 included patients with high (54.7%), extreme (17.0%), moderate (15.6%), and low (12.7%) pain burden, respectively. Patients in class 4 showed high levels of emotional distress, whereas emotional distress in the other classes corresponded to the levels of pain burden. While pain as well as physical and mental health improved in class 1, only the levels of depression and anxiety improved in patients in the other groups during multimodal treatment.

Conclusion

The specific needs of these subgroups should be taken into account when developing individualized treatment programs. However, the retrospective design limits the significance of the results and replication in prospective studies is desirable.

Pre-consultation biopsychosocial data from patients admitted for management at pain centers in Norway

Background and aims

A bio-psycho-social approach has been recommended in multidisciplinary pain clinics, and in Norway patients with severe chronic nonmalignant pain (CNMP, defined as pain that has persisted for more than 3 months) might be treated at a regional multidisciplinary pain center. The specific aims of this study were (1) to describe characteristics of a sample of outpatients referred and accepted for treatment/management to three regional multidisciplinary pain centers in Norway, (2) to examine patient differences between the centers and (3) to study associations between symptom scores (insomnia, fatigue, depression, anxiety) and patient characteristics.

Methods

Patients, aged 17 years or older with CNMP admitted to and given a date for first consultation at one of three tertiary, multidisciplinary pain centers: St. Olavs Hospital Trondheim University Hospital (STO), Haukeland University Hospital (HUS) and University Hospital of North Norway (UNN), were included in the study. Data on demographics, physical activity, characteristics of pain, previous traumatic events, social network, Insomnia Severity Index (ISI), Chalder Fatigue Questionnaire (CFQ), Hopkins Symptom Checklist-25 (HSCL-25) and SF-36v2® were retrieved from the local quality registry at each pain center.

Results

Data from 1563 patients [mean age 42 (SD 15) years and 63% females] were available for analyses. Average years with pain were 9.3 (SD 9.1). Primary education as highest level of education was reported by 20%, being actively working/student/military by 32%, and no physical activity by 31%. Further, 48% reported widespread pain, 61% reported being exposed to serious life event(s), and 77% reported having a close friend to talk to. Non-worker status, no physical activity, lack of social network, reports of being exposed to serious life event(s) and widespread pain were all characteristics repeatedly associated with clinically high symptom scores. No significant differences between the centers were found in the proportions of patients reporting fatigue nor mean levels of insomnia symptoms. However, the proportion of patients reporting symptoms of anxiety and depression was a little lower at UNN compared with STO and HUS.

Conclusions

Analyses of registry data from three tertiary multidisciplinary pain centers in Norway support previous findings from other registry studies regarding patient characterized: A large proportion being women, many years of pain, low employment rate, low physical activity rate, and a large proportion reporting previous traumatic event(s). Characteristics such as non-work participation, no physical activity, lack of social network, have been exposed to serious life event(s), and chronic widespread pain were all associated with high clinical score levels of insomnia, fatigue, and mental distress. Health related quality of life was low compared to what has been reported for a general population and a range of other patient groups.

Implications

The findings of this study indicate that physical activity and work participation might be two important factors to address in the rehabilitation of patients with chronic non-malignant pain. Future studies should also explore whether pre consultation self-reported data might give direction to rehabilitation modalities.

'A lifebuoy' and 'a waste of time': patients' varying experiences of multidisciplinary pain centre treatment- a qualitative study

Background

The recognition of chronic pain as a biopsychosocial phenomenon has led to the establishment of multidisciplinary pain treatment facilities, such as pain centres. Previous studies have focussed on inpatient, group-based or time-limited multidisciplinary pain programmes. The aim was to investigate variation in patients’ experiences of attending individual outpatient multidisciplinary treatment at pain centres in Norway.

Methods

This was a qualitative study using semi-structured individual interviews with 19 informants. The informants were recruited among persons who after referral by their general practitioners 12 months prior had attended multidisciplinary pain treatment at a pain centre. The data were analysed thematically using systematic text condensation.

Results

The informants had received different treatments at the pain centres. Some had undergone only one multidisciplinary assessment in which a physician, a psychologist and a physiotherapist had been present, whereas others had initially been to a multidisciplinary assessment and then continued treatment by one or more of the professionals at the centre. Their experiences ranged from the pain centre as being described as a lifebuoy by some informants who had attended treatment over time, to being described as a waste of time by others who had only attended one or two multidisciplinary sessions. Prominent experiences included being met with understanding and a perception of receiving the best possible treatment, but also included disappointment over not being offered any treatment and perceiving the multidisciplinary approach as unnecessary.

Conclusions

There were large variations in the informants’ experiences in the pain centres. The findings indicate that the pain centres’ multidisciplinary approach can represent a new approach to living with chronic pain but may also not provide anything new. Efforts should be devoted to ensuring that the pain centres’ multidisciplinary treatment approach is aligned with their patients’ actual needs.

Moderate and Stable Pain Reductions as a Result of Interdisciplinary Pain Rehabilitation-A Cohort Study from the Swedish Quality Registry for Pain Rehabilitation (SQRP)

Few studies have investigated the real-life outcomes of interdisciplinary multimodal pain rehabilitation programs (IMMRP) for chronic pain. This study has four aims: investigate effect sizes (ES); analyse correlation patterns of outcome changes; define a multivariate outcome measure; and investigate whether the clinical self-reported presentation pre-IMMRP predicts the multivariate outcome. To this end, this study analysed chronic pain patients in specialist care included in the Swedish Quality Registry for Pain Rehabilitation for 22 outcomes (pain, psychological distress, participation, and health) on three occasions: pre-IMMRP, post-IMMRP, and 12-month follow-up. Moderate stable ES were demonstrated for pain intensity, interference in daily life, vitality, and health; most other outcomes showed small ES. Using a Multivariate Improvement Score (MIS), we identified three clusters. Cluster 1 had marked positive MIS and was associated with the overall worst situation pre-IMMRP. However, the pre-IMMRP situation could only predict 8% of the variation in MIS. Specialist care IMPRPs showed moderate ES for pain, interference, vitality, and health. Outcomes were best for patients with the worst clinical presentation pre-IMMRP. It was not possible to predict who would clinically benefit most from IMMRP.

The importance of emotional distress, cognitive behavioural factors and pain for life impact at baseline and for outcomes after rehabilitation – a SQRP study of more than 20,000 chronic pain patients

Background and aims

Although literature concerning chronic pain patients indicates that cognitive behavioural variables, specifically acceptance and fear of movement/(re)injury, are related to life impact, the relative roles of these factors in relation to pain characteristics (e.g. intensity and spreading) and emotional distress are unclear. Moreover, how these variables affect rehabilitation outcomes in different subgroups is insufficiently understood. This study has two aims: (1) to investigate how pain, cognitive behavioural, and emotional distress variables intercorrelate and whether these variables can regress aspects of life impact and (2) to analyse whether these variables can be used to identify clinically meaningful subgroups at baseline and which subgroups benefit most from multimodal rehabilitation programs (MMRP) immediately after and at 12-month follow-up.

Methods

Pain aspects, background variables, psychological distress, cognitive behavioural variables, and two life impact variables were obtained from the Swedish Quality Registry for Pain Rehabilitation (SQRP) for chronic pain patients. These data were analysed mainly using advanced multivariate methods.

Results

The study includes 22,406 chronic pain patients. Many variables, including acceptance variables, showed important contributions to the variation in clinical presentations and in life impacts. Based on the statistically important variables considering the clinical presentation, three clusters/subgroups of patients were identified at baseline; from the worst clinical situation to the relatively good situation. These clusters showed significant differences in outcomes after participating in MMRP; the subgroup with the worst situation at baseline showed the most significant improvements.

Conclusions

Pain intensity/severity, emotional distress, acceptance, and life impacts were important for the clinical presentation and were used to identify three clusters with marked differences at baseline (i.e. before MMRP). Life impacts showed complex relationships with acceptance, pain intensity/severity, and emotional distress. The most significant improvements after MMRP were seen in the subgroup with the lowest level of functioning before treatment, indicating that patients with complex problems should be offered MMRP.

Implications

This study emphasizes the need to adopt a biopsychosocial perspective when assessing patients with chronic pain. Patients with chronic pain referred to specialist clinics are not homogenous in their clinical presentation. Instead we identified three distinct subgroups of patients. The outcomes of MMRP appears to be related to the clinical presentation. Thus, patients with the most severe clinical presentation show the most prominent improvements. However, even though this group of patients improve they still after MMRP show a complex situation and there is thus a need for optimizing the content of MMRP for these patients. The subgroup of patients with a relatively good situation with respect to pain, psychological distress, coping and life impact only showed minor improvements after MMRP. Hence, there is a need to develop other complex interventions for them.

Who benefits from multimodal rehabilitation - an exploration of pain, psychological distress, and life impacts in over 35,000 chronic pain patients identified in the Swedish Quality Registry for Pain Rehabilitation

BACKGROUND

Chronic pain patients frequently suffer from psychological symptoms. There is no consensus concerning the prevalence of severe anxiety and depressive symptoms and the strength of the associations between pain intensity and psychological distress. Although an important aspect of the clinical picture is understanding how the pain condition impacts life, little is known about the relative importance of pain and psychological symptoms for individual's life impact. The aims of this study were to identify subgroups of pain patients; to analyze if pain, psychological distress, and life impact variables influence subgrouping; and to investigate how patients in the subgroups benefit from treatments.

METHODS

Background variables, pain aspects (intensity/severity and spreading), psychological distress (depressive and anxiety symptoms), and two life impact variables (pain interference and perceived life control) were obtained from the Swedish Quality Registry for Pain Rehabilitation for chronic pain patients and analyzed mainly using advanced multivariate methods.

RESULTS

Based on >35,000 patients, 35%-40% had severe anxiety or depressive symptoms. Severe psychological distress was associated with being born outside Europe (21%-24% vs 6%-8% in the category without psychological distress) and low education level (20.7%-20.8% vs 26%-27% in the category without psychological distress). Dose relationships existed between the two psychological distress variables and pain aspects, but the explained variances were generally low. Pain intensity/severity and the two psychological distress variables were significantly associated (R 2=0.40-0.48; P>0.001) with the two life impact variables (pain interference and life control). Two subgroups of patients were identified at baseline (subgroup 1: n=15,901-16,119; subgroup 2: n=20,690-20,981) and the subgroup with the worst situation regarding all variables participated less in an MMRP (51% vs 58%, P<0.001) but showed the largest improvements in outcomes.

CONCLUSION

The results emphasize the need to assess both pain and psychological distress and not take for granted that pain involves high psychological stress in the individual case. Not all patients benefit from MMRP. A better matching between common clinical pictures and the content of MMRPs may help improve results. We only partly found support for treatment resistance in patients with psychological distress burden.