Dexamethasone and chronic postsurgical pain: the pendulum meets reductionistic thinking.

Reductionist thinking results in the bulk of anaesthesia trial designs being a single intervention to address what are in fact complex processes. The Perioperative Administration of Dexamethasone and Infection (PADDI) trial assessed the safety of a single preoperative dose of dexamethasone. Surprising to most, in the original report, a single dose of dexamethasone increased the incidence of the secondary outcome chronic postsurgical pain. Was this a chance finding or does dexamethasone increase chronic postsurgical pain? In an attempt to address this question, the PADDI investigators have now analysed this prespecified secondary outcome in two ways: as a substudy published earlier in this Journal, and as a retrospective analysis of the ENIGMA-II chronic pain database in this issue of the Journal. The PADDI investigators have now presented enough data to convince us that indeed a single dose of dexamethasone is safe and effective. However, the increase in chronic postsurgical pain seen in the original PADDI publication highlights the complexities, and the possible immunologic mechanisms, behind the genesis of chronic postsurgical pain. These publications from the PADDI group raise questions about other anti-inflammatory agents we use regularly for long-term postoperative pain management, and highlights the need for well-designed clinical trials to address this critically important patient-centred adverse functional outcome.

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

BACKGROUND: The purpose of this study was to determine the incidence, characteristics, impact, and risk factors associated with persistent incisional pain. The hypothesis was that patient demographics and perioperative interventions are associated with persistent pain. METHODS: This was a secondary analysis of an international prospective cohort study from 2012 to 2014. This study included patients who were 45 yr of age or older who underwent major inpatient noncardiac surgery. Data were collected perioperatively and at 1 yr after surgery to assess for the development of persistent incisional pain (pain present around incision at 1 yr after surgery). RESULTS: Among 14,831 patients, 495 (3.3%; 95% CI, 3.1 to 3.6) reported persistent incisional pain at 1 yr, with an average pain intensity of 3.6 ± 2.5 (0 to 10 numeric rating scale), with 35% and 14% reporting moderate and severe pain intensities, respectively. More than half of patients with persistent pain reported needing analgesic medications, and 85% reported interference with daily activities (denominator = 495 in the above proportions). Risk factors for persistent pain included female sex (P = 0.007), Asian ethnicity (P < 0.001), surgery for fracture (P < 0.001), history of chronic pain (P < 0.001), coronary artery disease (P < 0.001), history of tobacco use (P = 0.048), postoperative patient-controlled analgesia (P < 0.001), postoperative continuous nerve block (P = 0.010), insulin initiation within 24 h of surgery (P < 0.001), and withholding nonsteroidal anti-inflammatory medication or cyclooxygenase-2 inhibitors on the day of surgery (P = 0.029 and P < 0.001, respectively). Older age (P < 0.001), endoscopic surgery (P = 0.005), and South Asian (P < 0.001), Native American/Australian (P = 0.004), and Latin/Hispanic ethnicities (P < 0.001) were associated with a lower risk of persistent pain. CONCLUSIONS: Persistent incisional pain is a common complication of inpatient noncardiac surgery, occurring in approximately 1 in 30 adults. It results in significant morbidity, interferes with daily living, and is associated with persistent analgesic consumption. Certain demographics, ethnicities, and perioperative practices are associated with increased risk of persistent pain.

Interventional treatments for chronic, axial or radicular, non-cancer, spinal pain: a protocol for a systematic review and network meta-analysis of randomised trials.

INTRODUCTION: Chronic, non-cancer, axial or radicular spinal pain is a common condition associated with considerable socioeconomic burden. Clinicians frequently offer patients various interventional procedures for the treatment of chronic spine pain; however, the comparative effectiveness and safety of available procedures remains uncertain. METHODS: We will conduct a systematic review of randomised controlled trials that explores the effectiveness and harms of interventional procedures for the management of axial or radicular, chronic, non-cancer, spine pain. We will identify eligible studies through a systematic search of Medline, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials and Web of Science from inception without language restrictions. Eligible trials will: (1) enrol primarily adult patients (≥18 years old) with axial or radicular, chronic, non-cancer, spine pain, (2) randomise patients to different, currently available, interventional procedures or to an interventional procedure and a placebo/sham procedure or usual care, and (3) measure outcomes at least 1 month after randomisation.Pairs of reviewers will independently screen articles identified through searches and extract information and assess risk of bias of eligible trials. We will use a modified Cochrane instrument to evaluate risk of bias. We will use frequentist random-effects network meta-analyses to assess the relative effects of interventional procedures, and five a priori hypotheses to explore between studies subgroup effects. We will use the Grading of Recommendations Assessment, Development and Evaluation approach to assess the certainty in evidence for each outcome, including direct, indirect and network estimates. ETHICS AND DISSEMINATION: No research ethics approval is required for this systematic review, as no confidential patient data will be used. We will disseminate our findings through publication in a peer-reviewed journal and conference presentations, and our review will support development of a BMJ Rapid Recommendations providing contextualised clinical guidance based on this body of evidence. PROSPERO REGISTRATION NUMBER: CRD42020170667.

Opioid-sparing effects of medical cannabis or cannabinoids for chronic pain: a systematic review and meta-analysis of randomised and observational studies.

OBJECTIVE: To assess the efficacy and harms of adding medical cannabis to prescription opioids among people living with chronic pain. DESIGN: Systematic review. DATA SOURCES: CENTRAL, EMBASE and MEDLINE. MAIN OUTCOMES AND MEASURES: Opioid dose reduction, pain relief, sleep disturbance, physical and emotional functioning and adverse events. STUDY SELECTION CRITERIA AND METHODS: We included studies that enrolled patients with chronic pain receiving prescription opioids and explored the impact of adding medical cannabis. We used Grading of Recommendations Assessment, Development and Evaluation to assess the certainty of evidence for each outcome. RESULTS: Eligible studies included five randomised trials (all enrolling chronic cancer-pain patients) and 12 observational studies. All randomised trials instructed participants to maintain their opioid dose, which resulted in a very low certainty evidence that adding cannabis has little or no impact on opioid use (weighted mean difference (WMD) -3.4 milligram morphine equivalent (MME); 95% CI (CI) -12.7 to 5.8). Randomised trials provided high certainty evidence that cannabis addition had little or no effect on pain relief (WMD -0.18 cm; 95% CI -0.38 to 0.02; on a 10 cm Visual Analogue Scale (VAS) for pain) or sleep disturbance (WMD -0.22 cm; 95% CI -0.4 to -0.06; on a 10 cm VAS for sleep disturbance; minimally important difference is 1 cm) among chronic cancer pain patients. Addition of cannabis likely increases nausea (relative risk (RR) 1.43; 95% CI 1.04 to 1.96; risk difference (RD) 4%, 95% CI 0% to 7%) and vomiting (RR 1.5; 95% CI 1.01 to 2.24; RD 3%; 95% CI 0% to 6%) (both moderate certainty) and may have no effect on constipation (RR 0.85; 95% CI 0.54 to 1.35; RD -1%; 95% CI -4% to 2%) (low certainty). Eight observational studies provided very low certainty evidence that adding cannabis reduced opioid use (WMD -22.5 MME; 95% CI -43.06 to -1.97). CONCLUSION: Opioid-sparing effects of medical cannabis for chronic pain remain uncertain due to very low certainty evidence.PROSPERO registration numberCRD42018091098.

Response to "understanding the behavioural determinants of opioid prescribing among family physicians: a qualitative study".

The 2017 Canadian opioid Guideline made both strong recommendations, indicating that all or almost all fully informed patients would choose the recommended course of action, and weak recommendations, in which different choices are appropriate for individual patients based on their values and preferences. The Guideline's recommendation to taper legacy patients prescribed high-dose opioid therapy is weak, and mandatory tapering is expressly discouraged.

The role of anxiety and related states in pediatric postsurgical pain.

Background: Nearly 20% of children and adolescents have pain with disability 1 year after surgery, and they experience poor sleep, school absence, and decreased activities. Negative clinical, psychological, and developmental effects include greater pain medication use, longer recovery, and fear of future medical care. Research has found psychological and family influences (i.e., child and parental anxiety) on pediatric chronic postsurgical pain (CPSP), but a better understanding of the role of perioperative anxiety and its related states in predicting pediatric postsurgical pain is needed. The poor understanding of the causes of child CPSP can lead to misdiagnosis and inadequate treatment, with significant short- and long-term effects. Objectives: The aim of this review was to summarize the literature on children's perioperative anxiety and parental anxiety in relation to acute postsurgical pain, CPSP, and pain trajectories. We also examined other related psychological factors (i.e., anxiety sensitivity, catastrophizing, pain anxiety, and fear of pain) in relation to pediatric acute and chronic postsurgical pain. Lastly, we discuss the interventions that may be effective in reducing children's and parents' preoperative anxiety. Conclusions: Our findings may improve the understanding of the causes of CPSP and highlight the gaps in research and need for further study.

Contexte: Près de 20 % des enfants et adolescents ont des douleurs avec incapacité un après la chirurgie, et ils ont un mauvais sommeil, des absences scolaires et une diminution de leurs activités. Les effets cliniques, psychologiques et développementaux négatifs comprennent une utilisation accrue des analgésiques, une récupération plus longue et la peur des soins médicaux futurs. La recherche a révélé des influences psychologiques et familiales (c.-à-d. de l'anxiété chez les enfants et les parents) sur la douleur chronique postchirurgicale pédiatrique, mais une meilleure compréhension du rôle de l'anxiété périopératoire et ses états associés pour prédire la douleur postchirurgicale pédiatrique est nécessaire. Une mauvaise compréhension des causes de la douleur chronique postchirurgicale pédiatrique peut entraîner un diagnostic erroné et un traitement inadéquat, avec des effets importants à court et à long terme.Objectifs: Le but de cette revue était de résumer la littérature sur l'anxiété périopératoire des enfants et l'anxiété parentale en lien avec la douleur postchirurgicale aiguë, la douleur chronique postchirurgicale et les trajectoires de la douleur. Nous avons aussi examiné d'autres facteurs psychologiques connexes (ex. : sensibilité à l'anxiété, catastrophisme, anxiété de la douleur, et peur de la douleur) en lien avec la douleur chronique postchirurgicale pédiatrique aigue. Enfin, nous discutons des interventions qui peuvent être efficaces pour réduire l'anxiété préopératoire des enfants et des parents.Conclusions: Nos résultats peuvent améliorer la compréhension des causes de la douleur chronique postchirurgicale et mettre en évidence les lacunes dans la recherche, ainsi que la nécessité d'études plus poussées.

Perioperative Pregabalin and Intraoperative Lidocaine Infusion to Reduce Persistent Neuropathic Pain After Breast Cancer Surgery: A Multicenter, Factorial, Randomized, Controlled Pilot Trial.

Persistent postsurgical pain is defined as pain localized to the area of surgery of a duration of ≥2 months and is, unfortunately, a common complication after breast cancer surgery. Although there is insufficient evidence to support any preventative strategy, prior literature suggests the possible efficacy of intravenous lidocaine and perioperative pregabalin in preventing persistent pain after surgery. To determine feasibility of conducting a larger definitive trial, we conducted a multicenter 2 × 2 factorial, randomized, placebo-controlled pilot trial of 100 female patients undergoing breast cancer surgery. Patients were randomized to receive an intraoperative lidocaine infusion (1.5 mg/kg bolus followed by 2 mg/kg/h) or placebo and perioperative pregabalin (300 mg preoperatively, 75 mg twice daily for 9 days) or placebo. All feasibility criteria were surpassed; recruitment of 100 patients was accomplished within 42 weeks, with a follow-up rate of 100% and study drug compliance of ≥80%. At 3 months, 53% of patients reported persistent neuropathic pain. Although there was no interaction between lidocaine and pregabalin, lidocaine decreased the development of persistent neuropathic pain (43.1% vs 63.3%; relative risk = .68; 95% confidence interval = .47-1.0). Pregabalin did not reduce persistent pain (60% vs 46%; relative risk = 1.3; 95% confidence interval = .90-1.90) and neither pregabalin nor lidocaine impacted acute postoperative pain, opioid consumption, pain interference, or quality of life. Our pilot trial successfully demonstrated feasibility and provided promising data for conducting further trials of intraoperative lidocaine infusions during breast cancer surgeries. Clinical trial number: NCT02240199 PERSPECTIVE: This article reports the findings of a pilot randomized, controlled trial evaluating the effects of perioperative pregabalin and intraoperative lidocaine infusions in patients undergoing breast cancer surgery. This trial demonstrated the feasibility of conducting a larger trial and provided promising data that these interventions may decrease the development of persistent pain.

Examination of psychological risk factors for chronic pain following cardiac surgery: protocol for a prospective observational study.

INTRODUCTION: Approximately 400 000 Americans and 36 000 Canadians undergo cardiac surgery annually, and up to 56% will develop chronic postsurgical pain (CPSP). The primary aim of this study is to explore the association of pain-related beliefs and gender-based pain expectations on the development of CPSP. Secondary goals are to: (A) explore risk factors for poor functional status and patient-level cost of illness from a societal perspective up to 12 months following cardiac surgery; and (B) determine the impact of CPSP on quality-adjusted life years (QALYs) borne by cardiac surgery, in addition to the incremental cost for one additional QALY gained, among those who develop CPSP compared with those who do not. METHODS AND ANALYSES: In this prospective cohort study, 1250 adults undergoing cardiac surgery, including coronary artery bypass grafting and open-heart procedures, will be recruited over a 3-year period. Putative risk factors for CPSP will be captured prior to surgery, at postoperative day 3 (in hospital) and day 30 (at home). Outcome data will be collected via telephone interview at 6-month and 12-month follow-up. We will employ generalised estimating equations to model the primary (CPSP) and secondary outcomes (function and cost) while adjusting for prespecified model covariates. QALYs will be estimated by converting data from the Short Form-12 (version 2) to a utility score. ETHICS AND DISSEMINATION: This protocol has been approved by the responsible bodies at each of the hospital sites, and study enrolment began May 2015. We will disseminate our results through CardiacPain.Net, a web-based knowledge dissemination platform, presentation at international conferences and publications in scientific journals. TRIAL REGISTRATION NUMBER: NCT01842568.

Electronic Versus Traditional Data Collection: A Multicenter Randomized Controlled Perioperative Pain Trial.

Background: Electronic data collection is increasingly available as a means to collect pain-related clinical trial data; however, effectiveness and costs relative to traditional data collection are uncertain. Aims: The aim of this study was to evaluate data quality, protocol adherence, satisfaction, and resource requirements of electronic data collection (i.e., Internet-based electronic submission) compared to traditional data collection methods (i.e., paper-based diaries and telephone interviews) in a perioperative factorial randomized controlled trial. Methods: This study was an open-label two-arm parallel randomized controlled trial. Women (18-75 years) undergoing breast cancer surgery were allocated to either electronic or traditional data collection and completed pain-related questionnaires at baseline, postoperative period, and 3-month follow-up (NCT02240199). Results: We acquired outcome data at all time points from 78 randomized patients, 38 in the electronic group and 40 in the traditional group. The number of data queries (e.g., erroneously entered data) per patient was higher in the electronic data group (4.92 [SD = 4.67] vs. 1.88 [SD = 1.51]; P < 0.001). No between-group differences were observed for compliance with medications, data completeness, loss to follow-up, or patient or research assistant satisfaction. More research assistant time per patient was spent collecting data in the traditional group (42.6 min [SD = 12.8] vs. 9.92 min [SD = 7.6]; P < 0.001); however, costs per patient were higher in the electronic group ($176.85 [SD = 2.90] vs. $16.33 [SD = 4.90]; P < 0.001). Conclusion: Electronic data collection is feasible for perioperative pain clinical trials. Additional trials, including different surgical populations, are needed to confirm our findings and optimize use of electronic data capture methods.

Contexte: La collecte électronique de données est de plus en plus disponible en tant que moyen de recueillir les données dans le cadre d'essais cliniques liés à la douleur; toutefois, l'efficacité et le coût de cette méthode, comparativement à la collecte de données traditionnelle, sont incertains.But: Évaluer la qualité des données, le respect du protocole, la satisfaction et les ressources requises dans le cadre de la collecte électronique de données (i.e. la transmission électronique par Internet) comparativement aux méthodes de collecte de données traditionnelles (c.-à.-d les cahiers papier et les entrevues téléphoniques) dans un essai randomisé contrôllé factoriel périopératoire.Méthodes: Cette étude était un essai contrôlé randomisé ouvert parallèle à deux volets. Des femmes (de 18 à 75 ans) subissant une chirurgie pour traiter un cancer du sein ont été réparties en deux groupes, soit celui de la collecte életronique de données et celui de la collecte traditionnelle de données. Elles ont ensuite répondu à des questionnaires liés à la douleur au départ, pendant la période post-opératoire et au bout de trois mois (NCT02240199).Résutats: Nous avons receuilli les données de 78 patientes randomisées à chaque point dans le temps : 38 patientes dans le groupe électronique et 40 patientes dans le groupe traditionnel. Le nombre de questions relatives aux données (ex.: données saisies de manière erronée) par patiente était plus élevé dans le groupe de données électroniques (4,92, É.-T. 4,67 comparativement à 1,88, É.-T. 1,51; p < 0,001). Aucune différence n'a été observée entre les groupes en ce qui concerne l'observance du traitement médicamenteux, l'exhaustivité des données, le nombre de patientes perdues de vue et la satisfaction des patientes ou des assistantes de recherche. Les assistants de recherche ont passé plus de temps par patiente pour recueillir les données dans le groupe traditionnel (42,6 minutes É.-T. 12,8 comparativement à 9,92 minutes É.-T. 76; p < 0,001); toutefois, le coût par patiente était plus élevé dans le groupe électronique (176,85 $ É.-T. 2,90 comparativement à 16,33 $ É.-T. 4,90; p < 0,001).Conclusion: La collecte électronique de données est réalisable dans le cadre d'essais cliniques portant sur la douleur périopératoire. Des essais supplémentaires, y compris auprès de différentes populations de patients chirurgicaux, sont nécessaires pour confirmer nos résultats et optimiser l'utilisation de méthodes éectroniques de saisie de données.

Somatosensory rehabilitation for allodynia in complex regional pain syndrome of the upper limb: A retrospective cohort study.

STUDY DESIGN: Retrospective cohort study. INTRODUCTION: Somatosensory rehabilitation is a standardized method of evaluation and conservative treatment of painful disorders of vibrotactile sensation, including the mechanical allodynia and burning pain of complex regional pain syndrome (CRPS). PURPOSE OF THE STUDY: The purpose of this study was to examine the effectiveness of somatosensory rehabilitation for reducing allodynia in persons with CRPS of 1 upper limb in a retrospective consecutive cohort of patients. METHODS: An independent chart review of all client records (May 2004-August 2015) in the Somatosensory Rehabilitation Centre (Fribourg, Switzerland) identified 48 persons meeting the Budapest criteria for CRPS of 1 limb who had undergone assessment and treatment. Outcomes of interest were the French version of the McGill Pain Questionnaire (Questionnaire de la Douleur St-Antoine [QDSA]), total area of allodynia as recorded by mapping the area of skin where a 15-g monofilament was perceived as painful, and the allodynia threshold (minimum pressure required to elicit pain within the allodynic territory). RESULTS: This cohort was primarily women (70%), with a mean age of 45 years (range: 18-74). Mean duration of burning pain was 31 months (range: 1 week-27.5 years), and baseline QDSA core was 48. The average primary area of allodynia was 66 cm2 (range: 2.6-320), and the most common allodynia threshold was 4.0 g. The average duration of treatment was 81 days. At cessation of treatment, the average QDSA score was 20 (effect size Cohen's d = 1.64). Allodynia completely resolved in 27 persons (56% of the total sample where only 58% completed treatment). DISCUSSION: This uncontrolled retrospective study suggests that somatosensory rehabilitation may be an effective treatment with a large effect size for reducing the allodynia and painful sensations associated with CRPS of the upper limb. More work is in progress to provide estimates of reliability and validity for the measurement tools for allodynia employed by this method. LEVEL OF EVIDENCE: 2c.

Characteristics of patients receiving long-term opioid therapy for chronic noncancer pain: a cross-sectional survey of patients attending the Pain Management Centre at Hamilton General Hospital, Hamilton, Ontario.

BACKGROUND: Characteristics of patients receiving long-term opioid therapy (≥ 6 months) for chronic noncancer pain are poorly understood. We conducted a cross-sectional survey of this patient population to explore demographic variables, pain relief, functional improvement, adverse effects and impressions of an educational pamphlet on long-term opioid therapy. METHODS: We invited 260 adult patients presenting to the Pain Management Centre at the Hamilton General Hospital, Hamilton, Ontario, with chronic noncancer pain to complete a 20-item survey. Patients who presented for procedures were not eligible for our study. We used adjusted logistic regression models to explore the association between higher morphine equivalent dose and pain relief, functional improvement, adverse events and employment. RESULTS: The survey was completed by 170 patients (a response rate of 65.4%). Most respondents (87.6%; 149 out of 170) were receiving long-term opioid therapy, and the median morphine equivalent dose was 180 mg daily (interquartile range 60-501). Most respondents reported at least modest (> 40%) opioid-specific pain relief (74.1%; 106 out of 143) and functional improvement (67.6%; 96 out of 142), and 46.5% (66 out of 142) reported troublesome adverse effects that they attributed to their opioid use. Most patients were receiving disability benefits (68.3%; 99 out of 145) and, among those respondents who were less than 65 years of age (90.3%; 131 out of 145), 10 (7.6%) were working full-time and 14 (10.7%) part-time. In our adjusted analyses, higher morphine equivalent dose was associated with greater self-reported functional improvement (odds ratio [OR] 1.45, 95% confidence interval [CI] 1.07-1.96) but not with pain relief (OR 1.38, 95% CI 1.00-1.89), troublesome adverse effects (OR 0.92, 95% CI 0.70-1.20) or employment (OR 0.80, 95% CI 0.56-1.15). INTERPRETATION: Most outpatients receiving long-term opioid therapy for chronic noncancer pain at a tertiary care chronic pain clinic reported at least moderate pain relief and functional improvement; however, adverse effects were common and few patients were engaged in competitive employment.