Cognitive function in patients with chronic pain treated with opioids: characteristics and associated factors

The Effect of Alexithymia, Attention, and Pain Characteristics on Mentalizing Abilities Among Adults With Chronic Pain

Introduction: Impaired mentalizing abilities are found among persons with chronic pain, yet it is still unknown why. The current study focuses on mentalizing abilities and how these could be affected by different pain factors, alexithymia traits, and other aspects of psychological functioning (depression, anxiety, attention) in persons experiencing chronic pain.Methods: 71 participants (80.3% female; mean age 56.1 (SD = 13.1)) with subjectively reported chronic pain conditions participated in the study. Mentalizing abilities were assessed using an objective assessment of the Frith-Happé animations test. Alexithymia was measured using Toronto Alexithymia Scale. Subjectively reported data on various pain characteristics and other related psychological factors (depression, anxiety, attention) were collected. Bivariate linear regression analyses were used to identify variables that had statistically significant relationships with Frith-Happé test scores as dependent variables, which were then used to build multivariate models.Results: Mentalization task scores had no significant associations with alexithymia. However, in bivariate models, greater Frith-Happé animations categorisation score was associated with higher attention task scores (βs = .332, p = .005), higher education (βs = .317, p = .007), and lower level of depressiveness (βs = -.234, p = .049). Greater animations feelings scores were associated with less severe pain intensity (βs = -.322, p = .006), younger age (βs = -.399, p = .001), and better attention (βs = .383, p = .001). In multivariate analysis models predicting both animations categorisation and feelings scores, attention was found to be the only statistically significant factor (respectively, βs = .257, p = .029 and βs = .264, p = .035).Conclusions: No significant correlations were found between mentalizing abilities and alexithymic features in persons with chronic pain. Disruptions of attention was the most significant factor leading to lower mentalizing abilities in persons with chronic pain.

The missing mechanistic link: Improving behavioral treatment efficacy for pediatric chronic pain

Pediatric chronic pain is a significant global issue, with biopsychosocial factors contributing to the complexity of the condition. Studies have explored behavioral treatments for pediatric chronic pain, but these treatments have mixed efficacy for improving functional and psychological outcomes. Furthermore, the literature lacks an understanding of the biobehavioral mechanisms contributing to pediatric chronic pain treatment response. In this mini review, we focus on how neuroimaging has been used to identify biobehavioral mechanisms of different conditions and how this modality can be used in mechanistic clinical trials to identify markers of treatment response for pediatric chronic pain. We propose that mechanistic clinical trials, utilizing neuroimaging, are warranted to investigate how to optimize the efficacy of behavioral treatments for pediatric chronic pain patients across pain types and ages.

Kognition und Kraftfahreignung bei chronischem Schmerzsyndrom

Kognitive Auffälligkeiten bei Patienten mit chronischen Schmerzen finden in wissenschaftlichen Untersuchungen zunehmend Beachtung. Die Folgen dieser kognitiven Störungen in Bezug auf die Schmerzbewältigung, die Alltagsgestaltung und die Kraftfahreignung werden in der klinischen Praxis jedoch kaum berücksichtigt, obwohl die Hälfte aller Patienten davon betroffen ist. Die vorliegende Arbeit fasst die aktuelle Studienlage zusammen und diskutiert Möglichkeiten der Integration in die klinische und therapeutische Versorgung.

Comparison of the Impacts of Under-Treated Pain and Opioid Pain Medication on Cognitive Impairment

Purpose: To guide clinicians in balancing the risks and benefits of opioids when treating pain, we conducted two systematic reviews: 1) the impact of pain on cognitive function, and 2) the impact of opioids on cognitive function.

Methods: Part one addressed the impact of pain on cognitive impairment; Part two considered the impact of opioids on cognitive impairment. PubMed was used to search for eligible articles. For part one, 1786 articles were identified, of which 23 met our eligibility criteria. For part two, among 584 articles, 18 were found eligible.

Results: For part one, 16 studies concluded that patients with chronic pain showed impaired cognitive function; six studies found that chronic pain does not worsen cognitive function; one study concluded that the impact of pain on cognitive function differs based on the underlying cognitive status. For part two, 15 studies found that using opioids to control pain did not cause significant cognitive impairment, while three studies concluded the opposite. Studies evaluating older subjects did not observe different results from those in the whole population for both reviews.

Conclusion: The published literature indicates that moderate to severe pain can impair cognitive function, and that careful use of opioid analgesics in such subjects does not necessarily worsen cognition. Although our results are insufficient to support clear guidance due to heterogeneity of cohorts and outcomes, this study may assist primary care providers by rendering explicitly the factors to be considered by providers caring for this population with pain when opioids are considered.

Factors mediating pain-related risk for opioid use disorder

Pain is a complex experience with far-reaching organismal influences ranging from biological factors to those that are psychological and social. Such influences can serve as pain-related risk factors that represent susceptibilities to opioid use disorder. This review evaluates various pain-related risk factors to form a consensus on those that facilitate opioid abuse. Epidemiological findings represent a high degree of co-occurrence between chronic pain and opioid use disorder that is, in part, driven by an increase in the availability of opioid analgesics and the diversion of their use in a non-medical context. Brain imaging studies in individuals with chronic pain that use/abuse opioids suggest abuse-related mechanisms that are rooted within mesocorticolimbic processing. Preclinical studies suggest that pain states have a limited impact on increasing the rewarding effects of opioids. Indeed, many findings indicate a reduction in the rewarding and reinforcing effects of opioids during pain states. An increase in opioid use may be facilitated by an increase in the availability of opioids and a decrease in access to non-opioid reinforcers that require mobility or social interaction. Moreover, chronic pain and substance abuse conditions are known to impair cognitive function, resulting in deficits in attention and decision making that may promote opioid abuse. A better understanding of pain-related risk factors can improve our knowledge in the development of OUD in persons with pain conditions and can help identify appropriate treatment strategies. This article is part of the special issue on 'Vulnerabilities to Substance Abuse.'.

Insomnia-related Memory Impairment in Individuals With Very Complex Chronic Pain

OBJECTIVE

To investigate the specific effect of insomnia on neuropsychological functioning in patients with very complex chronic pain.

BACKGROUND

Individuals with insomnia disorder or chronic pain often experience cognitive deficits, with both conditions appearing to correlate with impairments in neuropsychological functions. As insomnia often occurs comorbid with chronic pain, distinguishing the differential effects of these two syndromes on an individual's neuropsychological functioning can be challenging. Comorbid depressive symptoms in these individuals, which may also affect cognitive function, may further obscure the associations between chronic pain, insomnia, and the neuropsychological profile.

METHODS

The neuropsychological function of 22 individuals with very complex chronic pain was assessed using specialized tests examining aspects of memory and executive functioning. The severity of insomnia, depression, and anxiety was measured using questionnaires, and pain levels were assessed using a visual analog scale. Pain medications were transformed to the morphine-equivalent daily dose.

RESULTS

Insomnia severity was found to predict memory function, accounting for 32.4% of the variance: A 1 SD increase in insomnia severity decreased memory function by 0.57 SD. The negative correlation between insomnia and memory was significant even after controlling for pain level, morphine-equivalent daily dose, and comorbid levels of anxiety and depression.

CONCLUSIONS

Insomnia severity independently predicted memory function in patients with very complex chronic pain, even after controlling for other factors known to impair cognitive function. Insomnia may possibly explain some of the cognitive impairments related to chronic pain; thus, screening for, and treating, sleep disturbances may be a central aspect of chronic pain rehabilitation.

Validation of a Battery of Neuropsychological Tests for Patients With Metastatic Cancer

This study aimed to investigate the psychometric properties of Trail Making Test (TMT), Continuous Reaction Time (CRT), Finger Tapping Test (FTT), Digit Span Test (DST), and Mini-Mental State Examination (MMSE) in Brazilian patients with metastatic cancer. Cognitive performance of 178 patients with metastatic cancer and 79 controls was assessed using the TMT, CRT, FTT, DST, and MMSE. Discriminant validity, concurrent validity, and reliability (39 patients were retested after 3-7 days) were investigated. Discriminant validity between groups was observed in TMT, DST, and MMSE. Measures of concurrent validity and cognitive performance were positively correlated with physical performance, education level, and better performance on MMSE. Negative correlations were observed between cognitive function, pain, anxiety, and depression. All tests but FTT demonstrated very good reliability. Thus, all neuropsychological tests but FTT showed psychometric properties that permit their use in clinical and research purposes in patients with metastatic cancer.

Prevalence, characteristics and treatment of chronic pain in elderly patients hospitalized in internal medicine wards

BACKGROUND

Chronic pain is a frequent characteristic of elderly people and represents an actual and still poorly debated topic.

OBJECTIVE

We investigated pain prevalence and intensity, and its pharmacological therapy in elderly patients hospitalized in 101 internal medicine wards.

METHODS

Taking advantage of the "REgistro POliterapie Società Italiana Medicina Interna" (REPOSI), we collected 2535 patients of whom almost a quarter was older than 85 years old. Among them, 582 patients were affected by pain (either chronic or acute) and 296 were diagnosed with chronic pain.

RESULTS

Patients with pain showed worse cognitive status, higher depression and comorbidities, and a longer duration of hospital stay compared to those without pain (all p < .0366). Patients with chronic pain revealed lower level of independency in their daily life, worse cognitive status and higher level of depression compared to acute pain patients (all p < .0156). Moreover, most of them were not treated for pain at admission (73.4%) and half of them was not treated with any analgesic drug at discharge (50.5%). This difference affected also the reported levels of pain intensity. Patients who received analgesics at both admission and discharge remained stable (p = .172). Conversely, those not treated at admission who received an analgesic treatment during the hospital stay decreased their perceived pain (p < .0001).

CONCLUSIONS

Our results show the need to focus more attention on the pharmacological treatment of chronic pain, especially in hospitalized elderly patients, in order to support them and facilitate their daily life after hospital discharge.

Effects of long-term opioid analgesics on cognitive performance and plasma cytokine concentrations in patients with chronic low back pain: a cross-sectional pilot study

INTRODUCTION

Cognitive performance and inflammation are altered in people with chronic low back pain (CLBP). Yet, the magnitude of these changes has been unclear because of the potential influence of opioid analgesics.

OBJECTIVES

This cross-sectional pilot study aimed to explore whether patients with CLBP receiving long-term opioid analgesics differed from patients not taking opioids on measures of cognitive performance and plasma cytokine concentrations.

METHODS

Patients with CLBP who were either taking (N = 18) or not taking (N = 22) opioids daily for 3 or more months were recruited from a tertiary care private hospital and compared with healthy adults (N = 20). All groups were administered validated questionnaires to assess depression, anxiety, and stress; a cognitive test of memory, attention, and executive function; and a peripheral blood draw to measure proinflammatory (IL-1β, IL-2, IL-8, IL-12p70, TNF-α, and IFN-γ), anti-inflammatory (IL-4, IL-10, and IL-13), and pleiotropic (IL-6) cytokine concentrations. Patients also completed pain-specific questionnaires.

RESULTS

Patients receiving opioid analgesics performed significantly (P < 0.05) worse in attention and had significantly (P < 0.05) lower pain self-efficacy beliefs than those patients not taking opioids. Patient groups did not differ in mean pain severity or pain interference scores, tests of memory and executive function, and mean plasma cytokine concentrations, despite long-term opioid analgesics.

CONCLUSION

Patients receiving long-term opioid analgesics for CLBP have minor differences when compared with patients not taking opioids. This has important clinical implications when considering long-term treatment for patients with CLBP.

The Relationship Between Chronic Pain and Neurocognitive Function: A Systematic Review

OBJECTIVE

Understanding the relationship between chronic pain and neurocognition has important implications for the assessment and treatment of patient experiencing pain. This paper provides an overview of the current literature examining the neurocognition-chronic pain relationship and suggests future avenues of research, along with a discussion of clinical implications of the literature findings. Consideration of potential moderators and mediators of this relationship, as well as a brief discussion of the importance of future research in special populations at particular risk for these problems, are also a focus of this paper.

METHODS

This systematic review summarizes the findings of clinical studies in which neurocognitive performance was measured in chronic pain samples. A literature search led to the inclusion of 53 articles in the review.

RESULTS

Studies of neurocognitive performance in clinical chronic pain samples support a relationship between chronic pain and neurocognitive abnormalities, particularly on tests of memory, attention, and processing speed, with mixed data regarding executive functioning.

DISCUSSION

Several factors may moderate or mediate the relationship between chronic pain and neurocognitive functioning, including mood symptoms, medication side effects, and intensity and/or chronicity of pain. Limitations in the literature include a paucity of methodologically rigorous studies controlling for confounding variables (eg, opioid analgesia) and a limited number of studies examining the relationship between chronic pain and traumatic brain injury (a potential precipitant of both pain and neurocognitive impairment). Nonetheless, findings from the existing literature have significant clinical implications, including for populations with heightened risk of both pain and neurocognitive disorders.

Optimizing Cognitive Function in Persons With Chronic Pain

OBJECTIVES

Cognitive functioning is commonly disrupted in people living with chronic pain, yet it is an aspect of pain that is often not routinely assessed in pain management settings, and there is a paucity of research on treatments or strategies to alleviate the problem. The purpose of this review is to outline recent research on cognitive deficits seen in chronic pain, to give an overview of the mechanisms involved, advocate cognitive functioning as an important target for treatment in pain populations, and discuss ways in which it may be assessed and potentially remediated.

METHODS

A narrative review.

RESULTS

There are several options for remediation, including compensatory, restorative, and neuromodulatory approaches to directly modify cognitive functioning, as well as physical, psychological, and medication optimization methods to target secondary factors (mood, sleep, and medications) that may interfere with cognition.

DISCUSSION

We highlight the potential to enhance cognitive functions and identify the major gaps in the research literature.

Everyday Executive Functioning in Chronic Pain: Specific Deficits in Working Memory and Emotion Control, Predicted by Mood, Medications, and Pain Interference

OBJECTIVES

People with chronic pain may experience impairments in high-level cognitive skills, particularly executive functions. Such impairments are not adequately measured in most clinical pain management settings yet could be a key influence on everyday functioning. We administered a well-validated, well-normed self-report measure to determine which aspects of executive functioning are compromised in the daily experience of patients with chronic pain, and whether these are associated with pain severity, medications, and mood.

MATERIALS AND METHODS

Sixty-three patients attending a multidisciplinary pain management clinic, and 66 pain-free age-matched and sex-matched controls, completed the Behavior Rating Inventory of Executive Function, Adult version (BRIEF-A). The BRIEF-A measures 9 aspects of executive function: Inhibit, Shift, Emotional Control, Initiate, Self-Monitor, Working Memory, Plan/Organize, Task Monitor, and Organization of Materials. Patients completed a battery of mood and pain-related measures.

RESULTS

Profile analysis revealed that patients with chronic pain reported significantly greater overall executive function impairments than controls. The patients showed greatest impairments on Working Memory and Emotional Control subscales, with more than half scoring in the clinically elevated range. A significant proportion of the variance in these scores was explained by total medication detriment (but not opioids alone), negative emotional states, and pain interference. Pain intensity and duration were not strong predictors of reported executive dysfunction.

DISCUSSION

Multiple factors impact on self-reported executive problems in this population. Specific deficits in Working Memory and Emotional Control have implications for patient engagement with treatment, and retention of information provided in therapy. A screening tool like the BRIEF-A may be useful in pain management settings.

Cognitive Effects and Sedation

OBJECTIVE

Cognitive effects and sedation (CES) are prevalent in chronic nonmalignant pain populations receiving long-term opioid therapy and are among the most common reasons patients discontinue opioid use. In this narrative review, we describe the phenomenology, epidemiology, mechanisms, assessment, and management of opioid-related CES.

DESIGN

We reviewed the empirical and theoretical literature on CES in opioid-treated populations with chronic pain. Data on long-term opioid therapy (≥ 3 months in duration) in chronic nonmalignant pain patients were sought.

RESULTS

The phenomenology of CES includes: inattention, concentration difficulties, memory deficits, psychomotor dysfunction, perceptual distortions, and executive dysfunction and somnolence, sleep disorders, and lethargy. Deficits may be caused by unrelieved pain or opioid therapy alone, or from a combination of these and other factors. Mechanisms include central nervous system effects, for example, direct toxic effects on neurons resulting in decreased consciousness; direct effects on processing and reaction resulting in cognitive or psychomotor impairment, and inhibitory effects on cholinergic activity. Pharmacological management approaches may include opioid dose reduction and rotation or psychostimulant use. Nonpharmacological approaches may include cognitive-behavioral therapy, mindfulness-based stress reduction, acupuncture, exercise, and yoga.

CONCLUSIONS

The most prevalent CES include: memory deficits (73-81%), sleep disturbance (35-57%), and fatigue (10%). At its most severe, extreme cognitive dysfunction can result in frank delirium and decreased alertness can result in coma. Emotional distress, sleep disorders, and other comorbidities and treatments can worsen CES, particularly among the elderly. Conclusions about the neuropsychological domains affected by opioids are limited due to the heterogeneity of studies and methodological issues.

Assessing the Construct Validity and Internal Reliability of the Screening Tool Test Your Memory in Patients with Chronic Pain

Patients with chronic pain often complain about cognitive difficulties, and since these symptoms represent an additional source of suffering and distress, evaluating the cognitive status of these patients with valid and reliable tests should be an important part of their overall assessment. Although cognitive impairment is a critical characteristic of pain, there is no specific measure designed to detect these effects in this population. The objective was to analyze the psychometric properties of the “Test Your Memory” (TYM) test in patients with chronic pain of three different origins. A cross-sectional study was carried out on 72 subjects free of pain and 254 patients suffering from different types of chronic pain: neuropathic pain (104), musculoskeletal pain (99) and fibromyalgia (51). The construct validity of the TYM was assessed using the Mini-Mental State Examination (MMSE), Hospital Anxiety and Depression Scale (HADs), Index-9 from MOS-sleep, SF-12, and through the intensity (Visual Analogical Scale) and duration of pain. An exploratory factor analysis was also performed and internal reliability was assessed using Cronbach’s alpha. After adjusting for potential confounders the TYM could distinguish between pain and pain-free patients, and it was correlated with the: MMSE (0.89, p<0.001); HAD-anxiety (-0.50, p<0.001) and HAD-depression scales (-0.52, p<0.001); MOS-sleep Index-9 (-0.49, p<0.001); and the physical (0.49, p < .001) and mental components (0.55, p < .001) of SF-12. The exploratory structure of the TYM showed an 8-factor solution that explained 53% of the variance, and Cronbach’s alpha was 0.66. The TYM is a valid and reliable screening instrument to assess cognitive function in chronic pain patients that will be of particular value in clinical situations.

Effect of topical application of melatonin cream 12.5% on cognitive parameters: A randomized, placebo-controlled, double-blind crossover study in healthy volunteers

BACKGROUND

Skin cancer is an increasing problem in modern dermatology. Earlier studies have shown protective effects against ultraviolet radiation (UVR)-induced skin damage by topical treatment with melatonin. However, the potential sedative effects of full body topical application of melatonin have never been investigated. Objectives The aim of this study was to assess the degree of cognitive dysfunction when using melatonin cream as full body topical application.

METHODS

In a randomized, placebo-controlled, double-blind crossover study in healthy volunteers, the degree of cognitive dysfunction when using cream containing 12.5% melatonin as full body application was assessed. A group of ten volunteers had melatonin cream 12.5% applied on 80% of their body surface area, and degree of cognitive dysfunction was assessed using a test battery consisting of Karolinska sleepiness scale (KSS), Finger tapping test (FTT) and Continuous Reaction time (CRT).

RESULTS

No significant effects on cognitive parameters were found. However, great inter-individual variations on cognitive parameters were observed.

CONCLUSION

This study was the first to assess degree of cognitive dysfunction resulting from application of melatonin cream on a full body surface area. The results support that melatonin is a safe drug for dermal application even in a high dosage.

Methods and Instruments to Evaluate Cognitive Function in Chronic Pain Patients: A Systematic Review

OBJECTIVE

We aimed to systematically review the methods and instruments used to evaluate cognitive function in chronic pain (CP) patients.

METHODS

A sensitive search strategy was designed using five databases. Based on the objectives and methodology, we selected cross-sectional studies on adults with chronic non-cancer pain in which cognitive function was assessed using validated instruments. The characteristics of the subjects, control groups, and other variables that might affect cognitive function, and the instruments used, were extracted from each article.

RESULTS

In the 42 articles identified, 53 instruments were used to assess cognitive function. Chronic pain criteria were defined in 83.3% of the articles and more than half (57.1%) included single diagnosis samples, with fibromyalgia being the most frequent studied (75%). Patients with prior cognitive impairment were excluded in 61.9% of the studies, and a control group was included in 64.3% of the studies. In most cases potential confounding variables were evaluated. More than 14% of the studies used self-report measures, and 73.8% used neuropsychological instruments, particularly for assessing attention (30%) and memory (27.5%). None of the instruments were specifically validated for pain patients and only five studies analyzed the psychometric properties of the instruments.

CONCLUSIONS

Various instruments and methods were used to assess cognitive function in CP patients, particularly fibromyalgia patients, but also other cohorts with well-defined CP. The instruments used had been validated, but not for pain populations, thus they require specific adaptation and validation to be used in CP patients. Certain recommendations are made in order to improve the evaluation of cognitive function in these patients.

Chronic pain treatment with opioid analgesics: benefits versus harms of long-term therapy

Chronic non-cancer pain (CNCP) is a disabling chronic condition with a high prevalence rate around the world. Opioids are routinely prescribed for treatment of chronic pain (CP). In the past two decades there has been a massive increase in the number of opioid prescriptions, prescribed daily opioid doses and overall opioid availability. Many more patients with CNCP receive high doses of long-acting opioids on a long-term basis. Yet CP and related disability rates remain high, and majority of the patients with CNCP are dissatisfied with their treatments. Intersecting with the upward trajectory in opioid use are the increasing trends in opioid related adverse effects, especially prescription drug abuse, addiction and overdose deaths. This complex situation raises questions on the relevance of opioid therapy in the treatment of CNCP. This article reviews current evidence on opioid effectiveness, the benefits and harms of long-term therapy in CNCP.

Does cognitive functioning predict chronic pain? Results from a prospective surgical cohort

It is well established that chronic pain impairs cognition, particularly memory, attention and mental flexibility. Overlaps have been found between the brain regions involved in pain modulation and cognition, including in particular the prefrontal cortex and the anterior cingulate cortex, which are involved in executive function, attention and memory. However, whether cognitive function may predict chronic pain has not been investigated. We addressed this question in surgical patients, because such patients can be followed prospectively and may have no pain before surgery. In this prospective longitudinal study, we investigated the links between executive function, visual memory and attention, as assessed by clinical measurements and the development of chronic pain, its severity and neuropathic symptoms (based on the 'Douleur Neuropathique 4' questionnaire), 6 and 12 months after surgery (total knee arthroplasty for osteoarthritis or breast surgery for cancer). Neuropsychological tests included the Trail-Making Test A and B, and the Rey-Osterrieth Complex Figure copy and immediate recall, which assess cognitive flexibility, visuospatial processing and visual memory. Anxiety, depression and coping strategies were also evaluated. In total, we investigated 189 patients before surgery: 96% were re-evaluated at 6 months, and 88% at 12 months. Multivariate logistic regression (stepwise selection) for the total group of patients indicated that the presence of clinical meaningful pain at 6 and 12 months (pain intensity ≥ 3/10) was predicted by poorer cognitive performance in the Trail Making Test B (P = 0.0009 and 0.02 for pain at 6 and 12 months, respectively), Rey-Osterrieth Complex Figure copy (P = 0.015 and 0.006 for pain at 6 and 12 months, respectively) and recall (P = 0.016 for pain at 12 months), independently of affective variables. Linear regression analyses indicated that impaired scores on these tests predicted pain intensity (P < 0.01) and neuropathic symptoms in patients with pain (P < 0.05), although the strength of the association was less robust for neuropathic symptoms. These results were not affected by the type of surgery or presurgical pain, similar findings being obtained specifically for patients who initially had no pain. In conclusion, these findings support, for the first time, the notion that premorbid limited cognitive flexibility and memory capacities may be linked to the mechanisms of pain chronicity and probably also to its neuropathic quality. This may imply that patients with deficits in executive functioning or memory because of cerebral conditions have a greater risk of pain chronicity after a painful event.

Is Pain Intensity Really That Important to Assess in Chronic Pain Patients? A Study Based on the Swedish Quality Registry for Pain Rehabilitation (SQRP)

BACKGROUND

Incorporating the patient's view on care and treatment has become increasingly important for health care. Patients describe the variety of consequences of their chronic pain conditions as significant pain intensity, depression, and anxiety. We hypothesised that intensities of common symptoms in chronic pain conditions carry important information that can be used to identify clinically relevant subgroups. This study has three aims: 1) to determine the importance of different symptoms with respect to participation and ill-health; 2) to identify subgroups based on data concerning important symptoms; and 3) to determine the secondary consequences for the identified subgroups with respect to participation and health factors.

METHODS AND SUBJECTS

This study is based on a cohort of patients referred to a multidisciplinary pain centre at a university hospital (n = 4645, participation rate 88%) in Sweden. The patients answered a number of questionnaires concerning symptoms, participation, and health aspects as a part of the Swedish Quality Registry for Pain Rehabilitation (SQRP).

RESULTS

Common symptoms (such as pain intensity, depression, and anxiety) in patients with chronic pain showed great variability across subjects and 60% of the cohort had normal values with respect to depressive and anxiety symptoms. Pain intensity more than psychological symptoms showed stronger relationships with participation and health. It was possible to identify subgroups based on pain intensity, depression, and anxiety. With respect to participation and health, high depressive symptomatology had greater negative consequences than high anxiety.

CONCLUSIONS

Common symptoms (such as pain intensity and depressive and anxiety symptoms) in chronic pain conditions carry important information that can be used to identify clinically relevant subgroups.