Altered serum bile acid profile in fibromyalgia is associated with specific gut microbiome changes and symptom severity.

ABSTRACT: Alterations in the composition and function of the gut microbiome in women with fibromyalgia have recently been demonstrated, including changes in the relative abundance of certain bile acid-metabolizing bacteria. Bile acids can affect multiple physiological processes, including visceral pain, but have yet to be explored for association to the fibromyalgia gut microbiome. In this study, 16S rRNA sequencing and targeted metabolomic approaches were used to characterize the gut microbiome and circulating bile acids in a cohort of 42 women with fibromyalgia and 42 healthy controls. Alterations in the relative abundance of several bacterial species known to metabolize bile acids were observed in women with fibromyalgia, accompanied by significant alterations in the serum concentration of secondary bile acids, including a marked depletion of α-muricholic acid. Statistical learning algorithms could accurately detect individuals with fibromyalgia using the concentration of these serum bile acids. Serum α-muricholic acid was highly correlated with symptom severity, including pain intensity and fatigue. Taken together, these findings suggest serum bile acid alterations are implicated in nociplastic pain. The changes observed in the composition of the gut microbiota and the concentration of circulating secondary bile acids seem congruent with the phenotype of increased nociception and are quantitatively correlated with symptom severity. This is a first demonstration of circulating bile acid alteration in individuals with fibromyalgia, potentially secondary to upstream gut microbiome alterations. If corroborated in independent studies, these observations may allow for the development of molecular diagnostic aids for fibromyalgia as well as mechanistic insights into the syndrome.

Predictors of Pain Reduction Among Fibromyalgia Patients Using Medical Cannabis: A Long-Term Prospective Cohort Study.

OBJECTIVE: Many patients with fibromyalgia (FM) report using cannabis as a strategy to improve pain. Given that pain often co-occurs with symptoms of anxiety and depression (i.e., negative affect) and sleep problems among patients with FM, improvements in these symptoms might indirectly contribute to reductions in pain intensity following cannabis use. The main objective of the study was to examine whether changes in pain intensity following initiation of medical cannabis among patients with FM could be attributed to concurrent changes (i.e., reductions) in negative affect and sleep problems. METHODS: This was a 12-month prospective cohort study among patients with FM (n = 323) initiating medical cannabis under the care of physicians. Patients were assessed at baseline, and follow-up assessment visits occurred every 3 months after initiation of medical cannabis. Patients' levels of pain intensity, negative affect, and sleep problems were assessed across all visits. RESULTS: Multilevel mediation analyses indicated that reductions in patients' levels of pain intensity were partly explained by concurrent reductions in sleep problems and negative affect (both P < 0.001). This remained significant even when accounting for patients' baseline characteristics or changes in medical cannabis directives over time (all P > 0.05). CONCLUSION: Our findings provide preliminary insight into the potential mechanisms of action underlying pain reductions among patients with FM who are using medical cannabis. Given the high attrition rate (i.e., 75%) observed in the present study at 12 months, our findings cannot be generalized to all patients with FM who are using medical cannabis.

Transitional Pain Care in Quebec: Did We Forget Our Youths? A Brief Research Report.

Adolescents and young adults (AYAs) represent a unique population with distinct psycho-social risks and care needs. About 10% of AYAs live with chronic pain (CP) and transition to adult pain care between 16 and 25 years of age. These transitions in care happen simultaneously with other bio-psycho-social changes and require flexible multi-disciplinary support models. As it stands, transitional pain care appears suboptimal, fragmented, and opportunistic in Quebec (Canada). The objective of this Brief Report is, therefore, to present our study findings and propose a multi-disciplinary transitional framework vision applicable to AYAs living with CP. Data were collected using a sequential-consensual qualitative design with a longitudinal participatory component. The consecutive stages of this work included an exploratory stage, semi-structured interviews with primary care providers, and inter-disciplinary deliberative stakeholder consultation groups. The deductive inductive thematic approach and the three-level Health Care Transition Research Consortium's theoretical framework were used to analyze the data. A representative group of stakeholders discussed findings from the first two steps, made fifteen actionable recommendations and formulated their vision of a transitional pain care model that can be further adapted in other settings. The study results present important insights into various psycho-social factors associated with transitional pain care for AYAs.

Dietary Intake Is Unlikely to Explain Symptom Severity and Syndrome-Specific Microbiome Alterations in a Cohort of Women with Fibromyalgia.

BACKGROUND: Significant alterations were recently identified in the composition and putative function of the gut microbiome in women with fibromyalgia. As diet can influence the composition of the gut microbiome, differences in nutritional intake could, in theory, account for some of these specific fibromyalgia microbiome alterations. The current study aims to compare the diet of women with fibromyalgia to that of controls in order to explore possible associations between the intake of certain nutrients, symptom severity and gut microbiome composition. METHODS: The study population was comprised of 56 women with fibromyalgia and 68 controls. Dietary intake was assessed using the NIH Automated Self-Administered 24 h recall, following dietitian's instructions and the completion of a three-day dietary recall. The gut microbiome was assessed by 16S ribosomal RNA gene sequencing of stool samples. RESULTS: Most demographic and anthropometric characteristics were comparable between groups. The average energy and macronutrient intake (total and relative) and overall diet quality score were not different between patients and controls, nor were the main vitamins, minerals, fatty acids, alcohol, caffeine, sugar or fiber intakes. The daily intake of micronutrients and normalized macronutrients in women with fibromyalgia was largely not correlated with disease-specific measures, including pain intensity, fatigue, cognitive symptoms and quality of sleep, or with the relative quantity of almost any of the gut microbiome bacterial taxa differentially abundant in fibromyalgia. CONCLUSION: These data demonstrate that dietary intakes, as evaluated by self-reported questionnaires, probably cannot explain the syndrome-specific differences in gut microbiome or the clinical phenotype of fibromyalgia.

Fluoroscopy-Guided High-Intensity Focused Ultrasound Neurotomy of the Lumbar Zygapophyseal Joints: A Clinical Pilot Study.

OBJECTIVE: To investigate the safety and feasibility of a fluoroscopy-guided, high-intensity focused ultrasound system for zygapophyseal joint denervation as a treatment for chronic low back pain. METHODS: The clinical pilot study was performed on 10 participants diagnosed with lumbar zygapophyseal joint syndrome. Each participant had a documented positive response to a diagnostic block or a previous, clinically beneficial radiofrequency ablation. For a descriptive study, the primary outcome was the safety question. All device- or procedure-related adverse events were collected. Secondary outcome variables included the average numeric rating scale for pain, the Roland-Morris Disability Questionnaire, the Brief Pain Inventory, the Patient Global Impression of Change, the morphine equivalent dose, and the finding of the neurological examination. RESULTS: All participants tolerated the procedure well with no significant device- or procedure-related adverse events; there was one episode of transient pain during the procedure. The average numeric rating scale score for pain decreased from 6.2 at baseline to 2.1 (n = 10) after 1 month, 4.9 (n = 9) after 3 months, 3.0 (n = 8) after 6 months, and 3.0 (n = 6) after 12 months. The ratio of participants who were considered a treatment success was 90% at 1 month, 50% at 3 months, 60% at 6 months, and 40% at 12 months. CONCLUSIONS: The first clinical pilot study using a noninvasive, fluoroscopy-guided, high-intensity focused ultrasound lumbar zygapophyseal neurotomy resulted in no significant device- or procedure-related adverse events and achieved clinical success comparable with that of routine radiofrequency ablation.

Epigenetic signature of chronic low back pain in human T cells.

OBJECTIVE: Determine if chronic low back pain (LBP) is associated with DNA methylation signatures in human T cells that will reveal novel mechanisms and potential therapeutic targets and explore the feasibility of epigenetic diagnostic markers for pain-related pathophysiology. METHODS: Genome-wide DNA methylation analysis of 850,000 CpG sites in women and men with chronic LBP and pain-free controls was performed. T cells were isolated (discovery cohort, n = 32) and used to identify differentially methylated CpG sites, and gene ontologies and molecular pathways were identified. A polygenic DNA methylation score for LBP was generated in both women and men. Validation was performed in an independent cohort (validation cohort, n = 63) of chronic LBP and healthy controls. RESULTS: Analysis with the discovery cohort revealed a total of 2,496 and 419 differentially methylated CpGs in women and men, respectively. In women, most of these sites were hypomethylated and enriched in genes with functions in the extracellular matrix, in the immune system (ie, cytokines), or in epigenetic processes. In men, a unique chronic LBP DNA methylation signature was identified characterized by significant enrichment for genes from the major histocompatibility complex. Sex-specific polygenic DNA methylation scores were generated to estimate the pain status of each individual and confirmed in the validation cohort using pyrosequencing. CONCLUSION: This study reveals sex-specific DNA methylation signatures in human T cells that discriminates chronic LBP participants from healthy controls.

Day-to-day opioid withdrawal symptoms, psychological distress, and opioid craving in patients with chronic pain prescribed opioid therapy.

BACKGROUND: Research has shown that opioid craving is one of the strongest determinants of opioid misuse in patients with chronic pain. To date, however, little is known on the factors that contribute to opioid craving in these patients. It is possible that patients' physical dependence to opioids, manifested by opioid withdrawal symptoms in between daily opioid doses, contribute to opioid craving. Physical dependence symptoms might also lead to psychological distress, which in turn might contribute to opioid craving. The first objective of this study was to examine the day-to-day association between opioid withdrawal symptoms and opioid craving among patients with chronic pain. We also examined whether negative affect and catastrophic thinking mediated this association. METHODS: In this longitudinal study, chronic pain patients (n = 79) prescribed short-acting opioids completed daily diaries for 14 consecutive days. Diaries assessed a host of pain, psychological, and opioid-related variables. RESULTS: Day-to-day elevations in opioid withdrawal symptoms were associated with heightened opioid craving (p < .001). Results of a multilevel mediation analysis revealed that this association was mediated by patients' daily levels of negative affect and catastrophizing (p < .001). CONCLUSIONS: Our study provides valuable new insights into our understanding of factors that may contribute to prescription opioid craving among patients with chronic pain.

Use of medical cannabis by patients with fibromyalgia in Canada after cannabis legalisation: a cross-sectional study.

OBJECTIVES: Medications have only small to moderate effects on symptoms in fibromyalgia (FM). Cannabinoids, including medical cannabis (MC) may have potential to fill this gap. Since recreational legalisation of cannabis in Canada, patients have easier access and may be self-medicating with cannabis. We have examined the prevalence and characteristics of MC use in FM patients. METHODS: During a two-month period (June-August 2019), consecutive attending rheumatology patients participated in an onsite survey comprising 2 questionnaires: 1) demographic and disease information completed by the rheumatologist, 2) patient anonymous questionnaire of health status, cannabis use (recreational and/or medicinal) and characteristics of use. RESULTS: In a cohort of 1000 rheumatology attendees, 117 (11.7%) were diagnosed with FM. Ever use of MC was reported by 28 (23.9%; 95%CI: 16.5%-32.7%) FM patients compared to 98 (11.1%; 95%CI: 9.1%-13.4%) non-FM patients. Among FM ever users, 17 (61%) patients continued use of MC. FM ever users vs. FM nonusers tended to be younger, 53 vs. 58 years (p=0.072), were more likely unemployed or disabled 39% vs. 17% (p=0.019) and used more medication types (p=0.013) but did not differ in symptom severity parameters. Cigarette smoking and recreational cannabis were more common in ever users. Global symptom relief on a VAS (1-10) was 7.0±2.3. CONCLUSIONS: FM patients have commonly used MC, with more than half continuing use. Reported symptom relief was substantial. Cigarette smoking and recreational cannabis use may play a facilitatory role in MC use in FM. Adjunctive MC may be a treatment consideration for some FM patients.

Day-to-day hedonic and calming effects of opioids, opioid craving, and opioid misuse among patients with chronic pain prescribed long-term opioid therapy.

ABSTRACT: Concerns have been raised regarding the misuse of opioids among patients with chronic pain. Although a number of factors may contribute to opioid misuse, research has yet to examine if the hedonic and calming effects that can potentially accompany the use of opioids contribute to opioid misuse. The first objective of this study was to examine the degree to which the hedonic and calming effects of opioids contribute to opioid misuse in patients with chronic pain. We also examined whether the hedonic and calming effects of opioids contribute to patients' daily levels of opioid craving, and whether these associations were moderated by patients' daily levels of pain intensity, catastrophizing, negative affect, or positive affect. In this longitudinal diary study, patients (n = 103) prescribed opioid therapy completed daily diaries for 14 consecutive days. Diaries assessed a host of pain, psychological, and opioid-related variables. The hedonic and calming effects of opioids were not significantly associated with any type of opioid misuse behavior. However, greater hedonic and calming effects were associated with heightened reports of opioid craving (both P's < 0.005). Analyses revealed that these associations were moderated by patients' daily levels of pain intensity, catastrophizing, and negative affect (all P's < 0.001). Results from this study provide valuable new insights into our understanding of factors that may contribute to opioid craving among patients with chronic pain who are prescribed long-term opioid therapy. The implications of our findings for the management of patients with chronic pain are discussed.

The effect of a topical combination of clonidine and pentoxifylline on post-traumatic neuropathic pain patients: study protocol for a randomized, double-blind placebo-controlled trial.

BACKGROUND: First-line pharmacotherapy for neuropathic pain entails the use of systemic antidepressants and anticonvulsants. These drugs are not optimally effective and poorly tolerated, especially for older patients with comorbid conditions. Given the high number of such patients, there is a need for a greater repertoire of safer and more effective analgesics. Clonidine and pentoxifylline are vasodilator agents that work synergistically to enhance tissue perfusion and oxygenation. The topical administration of these drugs, individually and in combination, has shown anti-nociceptive properties in rodent models of neuropathic pain. A topically-administered combination of clonidine and pentoxifylline also effectively reduced the intensity of both spontaneous and evoked pain in healthy volunteers with experimentally-induced neuropathic pain. The next step in advancing this formulation to clinical use is the undertaking of a phase II clinical study to assess its efficacy and safety in neuropathic pain patients. METHODS/DESIGN: This is a study protocol for a randomized, double-blind, placebo-controlled, phase II clinical trial with a cross-over design. It is a single-centered, 5-week study that will enroll a total of 32 patients with post-traumatic peripheral neuropathic pain. Patients will be treated topically with either a combination of clonidine and pentoxifylline or placebo for a period of 2 weeks each, in randomly assigned order across patients, with an intervening washout period of 1 week. The primary outcome measures of the study are the intensity of spontaneous pain recorded daily in a pain diary with a visual analog scale, and the degree of mechanical allodynia evoked by a brush stimulus. The secondary outcome measures of the study include scores of pain relief and change in the area of punctate hyperalgesia. This trial has been prospectively registered with ClinicalTrials.gov on November 1, 2017. ClinicalTrials.gov Identifier: NCT03342950 . DISCUSSION: The analgesic use of topical treatment with clonidine and pentoxifylline in combination has not been investigated in post-traumatic neuropathic pain. This study could generate the first evidence for the efficacy and safety of the formulation in alleviating pain in patients with neuropathic pain. Furthermore, this trial will provide objective grounds for the investigation of other agents that enhance tissue oxygenation in the topical treatment of peripheral neuropathic pain. TRIAL REGISTRATION: This trial has been registered with ClinicalTrials.gov owned by NIH's US National Library of Medicine. ClinicalTrials.gov NCT03342950 . Registered on November 1, 2017 (trial was prospectively registered). PROTOCOL VERSION AND IDENTIFIERS: This is protocol version 5, dated June 2018. McGill University Health Center (MUHC) Reaseach Ethics Board (REB) identification number: TTNP 2018-3906.

Tolerability and Feasibility of X-ray Guided Non-Invasive Ablation of the Medial Branch Nerve with Focused Ultrasound: Preliminary Proof of Concept in a Pre-clinical Model.

Four to six million patients a year in the United States suffer from chronic pain caused by facet joint degeneration. Thermal ablation of the affected facet joint's sensory nerve using radiofrequency electrodes is the therapeutic standard of care. High-intensity focused ultrasound (HIFU) is a novel technology enabling image-guided non-invasive thermal ablation of tissue. Six pigs underwent fluoroscopy-guided HIFU of the medial branch nerve and were followed up for 1 wk (two pigs), 1 mo (two pigs) and 3 mo (two pigs). At the end of each follow-up period, the animals were sacrificed, and targeted tissue was excised and evaluated with computed tomography scans as well as by macro- and micropathology. No significant adverse events were recorded during the procedure or follow-up period. All targets were successfully ablated. X-Ray-guided HIFU is a feasible and promising alternative to radiofrequency ablation of the lumbar facet joint sensory nerve.

Medical Cannabis Use by Rheumatology Patients Following Recreational Legalization: A Prospective Observational Study of 1000 Patients in Canada.

OBJECTIVE: Recreational legalization of cannabis may influence the medical use by patients. When only medical access was legally available in Canada, 4.3% of rheumatology patients reported use. With the current recreational legalization, we have reexamined the prevalence and characteristics of medical cannabis use in this same rheumatology setting. METHODS: Consecutively attending rheumatology patients participated in an onsite survey comprising the following two questionnaires: 1) demographic and disease information completed by the rheumatologist and 2) patient anonymous questionnaire of health status, cannabis use (recreational and/or medicinal), and characteristics of cannabis use. RESULTS: Of 1047 attendees from June to August 2019, with 1000 participating, medical cannabis had been used by 12.6% of patients (95% confidence interval 10.7%-14.8%), with half continuing use for mostly pain relief. Discontinuation was due to lack of effect in 57% of patients and side effects in 28% of patients. Ever medical users were younger (61.2 vs. 64.9 years; P = 0.006), more likely unemployed/disabled (16.7% vs. 5.9%; P < 0.001), and had more previous (47.6% vs. 25.5%; P < 0.001) and current recreational cannabis use (17.5% vs. 3.1%; P < 0.001) than nonusers. Most patients used multiple methods of administration, including smoking, vaporizing, and using oral oil preparations, but were poorly knowledgeable of product content, which was bought solely via the legal medical route by only 20%, and only one-third disclosed their use to the rheumatologist. CONCLUSION: Medical cannabis use has tripled for rheumatology patients since recreational legalization, with users being younger, not working, and having recreational cannabis experience. Concerning issues are the poor knowledge of the product being used, access via the nonmedical route, and nondisclosure to the physician.

Altered microbiome composition in individuals with fibromyalgia.

Fibromyalgia (FM) is a prevalent syndrome, characterised by chronic widespread pain, fatigue, and impaired sleep, that is challenging to diagnose and difficult to treat. The microbiomes of 77 women with FM and that of 79 control participants were compared using 16S rRNA gene amplification and whole-genome sequencing. When comparing FM patients with unrelated controls using differential abundance analysis, significant differences were revealed in several bacterial taxa. Variance in the composition of the microbiomes was explained by FM-related variables more than by any other innate or environmental variable and correlated with clinical indices of FM. In line with observed alteration in butyrate-metabolising species, targeted serum metabolite analysis verified differences in the serum levels of butyrate and propionate in FM patients. Using machine-learning algorithms, the microbiome composition alone allowed for the classification of patients and controls (receiver operating characteristic area under the curve 87.8%). To the best of our knowledge, this is the first demonstration of gut microbiome alteration in nonvisceral pain. This observation paves the way for further studies, elucidating the pathophysiology of FM, developing diagnostic aids and possibly allowing for new treatment modalities to be explored.

Development and validation of the Treatment Expectations in Chronic Pain Scale.

OBJECTIVES: To develop and examine the psychometric properties of the Treatment Expectations in Chronic Pain (TEC) scale, a brief measure of treatment expectations of chronic non-cancer pain treatment. DESIGN: A cross-sectional study design was used. METHODS: After conducting a literature review and expert discussions, a preliminary version of the TEC scale was developed. Cognitive interviews with 10 clinicians and 14 patients were conducted to examine the scale's face validity and item wording. Last, two hundred and five patients on the waitlist for a multidisciplinary pain treatment centre completed a battery of self-report questionnaires to examine the TEC scale's reliability and construct validity. Mokken scale analysis was conducted to select the final items. Reliability (Cronbach's alpha and Guttman's lambda2 ) and construct validity (Pearson correlations) were assessed. RESULTS: The final scale was composed of nine items that each measured ideal and predicted expectations about process and outcome of treatment. Mokken scale analysis showed the presence of two subscales: ideal and predicted expectations. The TEC scale had good internal consistency (α = 0.876-0.869) and adequate discriminant validity as assessed by its low correlation with measures of depression, anxiety, and quality of life (r = -.038 to .114). The scale had however low correlation with a theoretically related measure of optimism (r = .240). CONCLUSION: The TEC scale is a reliable scale measuring pain treatment expectation. Further evaluation of its psychometric properties is needed. The scale has the potential to deepen our understanding of the role treatment expectations play in chronic non-cancer pain treatment response. Statement of contribution What is already known on this subject? Expectations play a role in pain perception and the response to pain treatment Patients' expectations about pain and its management are associated with treatment satisfaction The absence of a validated tool to measure treatment expectations in chronic non-cancer pain prevents further exploration and understanding of the role of expectations in the context of multidisciplinary pain treatment . What does this study add? A new, reliable 9-item scale measuring treatment expectations among chronic non-cancer pain patients attending specialized multidisciplinary pain clinics .

Substance-related disorders: A review of prevalence and correlates among patients with chronic pain.

Over the past few decades, research has revealed high rates of substance-related disorders among patients with chronic pain. In addition to their potentially deleterious health consequences, substance-related disorders have consistently been associated with negative pain-related outcomes among patients with chronic pain. The goal of this narrative review was to provide an overview of studies that have examined the prevalence and correlates of substance-related disorders among patients with chronic pain. A particular focus was placed on opioids, sedatives/hypnotics, cannabis, tobacco, and alcohol given that these substances have received the bulk of research attention among patients with pain. Research conducted to date suggests that a host of biological and psychological factors are likely to contribute to the elevated rates of substance-related disorders among patients with chronic pain. In this review, in addition to reviewing the prevalence and correlates of substance-related disorders among patients with pain, we briefly discussed the changes that were recently made from the DSM-4 to the DSM-5 in the diagnostic criteria for substance-related disorders, and the implications of these changes for the assessment of patients with chronic pain. We also provided a brief overview of instruments that can be used for the assessment of these disorders in clinical and research settings.

Triage processes at multidisciplinary chronic pain clinics: An international review of current procedures.

Background: Multidisciplinary pain clinics are considered the gold standard for the treatment of chronic pain, yet access to such clinics is difficult and patients' conditions deteriorate while waiting. Instituting a triage process is one way of reducing wait time for some patients and ensuring optimal access given the limited resources available. Surprisingly, there are no established guidelines on how to optimally triage chronic pain patients at tertiary multidisciplinary pain clinics. Aims: The goal of this study was to gather information regarding existing triage systems in multidisciplinary chronic pain clinics worldwide as an initial step toward establishing a definitive evidence-based set of triage guidelines. Methods: A total of 66 multidisciplinary pain clinics worldwide completed an online survey detailing current triage practices at their clinic. The survey was distributed via international and national pain associations. Results: Results showed that the vast majority of multidisciplinary pain clinics (94%) use a triage system, yet many difficulties with these systems have been identified (time requirement, administrative burden, lack of control over scheduling, missing high-priority patients, and prioritizing low-priority patients). The level of satisfaction was noted to be higher in those clinics using a structured triage template. Conclusions: This study identified a need for the elaboration of best practice clinical guidelines for triage processes at tertiary pain clinics. The use of a structured referral template could become a central element to such guidelines.

Contexte: Les cliniques multidisciplinaires de la douleur sont considérées comme l'exemple idéal pour le traitement de la douleur chronique. L'accès à ces cliniques est toutefois difficile, de sorte que l'état de santé des patients se détériore pendant la période d'attente. L'instauration d'un processus de triage est l'une des façons de réduire le temps d'attente pour certains patients et d'assurer un accès optimal aux ressources limitées qui sont disponibles.Objectifs: Le but de cette étude était de recueillir de l'information concernant les systèmes de triage existants dans les cliniques multidisciplinaires de la douleur à travers le monde, comme première étape vers l'établissement de lignes directrices définitives fondées sur des données probantes.Méthodes: Au total, 66 cliniques multidisciplinaires de la douleur à travers le monde ont répondu à un sondage en ligne portant sur les pratiques de triage dans leur clinique. Le sondage a été distribué par l'entremise d'associations nationales et internationales de la douleur.Résultats: Les résultats ont démontré que la vaste majorité des cliniques multidisciplinaires de la douleur (94 %) utilisent un système de triage. Toutefois, de nombreuses difficultés ont été recensées en lien avec ces systèmes (temps nécessaire, fardeau administratif, manque de contrôle sur la prise de rendez-vous, difficulté à identifier certains patients prioritaires et priorisation des patients non prioritaires). Le niveau de satisfaction était plus élevé dans les cliniques qui utilisaient un modèle de référence structuré pour le triage.Conclusions: Cette étude a mis en évidence la nécessité d'élaborer des lignes directrices cliniques indiquant les pratiques exemplaires pour les processus de triage dans les cliniques de la douleur de niveau tertiaire. L'utilisation d'un modèle de référence structuré pourrait être un élément central de ces lignes directrices.