The Placebo Effect in Pain Therapies

Systematic review of pharmacotherapy for atypical facial pain: evaluation of pain reduction, depression, anxiety and quality of life

BACKGROUND/PURPOSE

Atypical facial pain (AFP) is a chronic condition characterized by persistent facial pain without clear clinical signs, making diagnosis and treatment difficult. Common pharmacological treatments include antidepressants, anticonvulsants and neuromodulators, but their effectiveness remains uncertain, necessitating a systematic review to guide clinical practice.

MATERIALS AND METHODS

Following PRISMA 2020 guidelines, randomized controlled trials (RCTs) evaluating pharmacological treatments for AFP in adults were included. A comprehensive search of five databases without date restrictions was performed. Data on pain reduction, quality of life, and adverse events were extracted. The Cochrane Risk of Bias (RoB 2.0) tool assessed bias, and evidence quality was evaluated using the Critical Appraisal Skills Programme tool.

RESULTS

Out of 196 studies identified, 10 RCTs met the inclusion criteria. Pharmacological responses varied significantly across studies. Antidepressants such as dothiepin and clomipramine demonstrated significant pain reduction, whereas venlafaxine showed limited efficacy. However, onabotulinum toxin A and sumatriptan exhibited inconsistent or minimal effects on AFP pain intensity. Adverse events were reported across multiple treatments, ranging from mild side effects such as dry mouth and nausea to severe reactions like diplopia and facial asymmetry, which impacted adherence. Despite some positive outcomes, the heterogeneity in study methodologies, outcome measures, and follow-up durations limited direct comparisons between interventions.

CONCLUSION

This systematic review highlights the mixed efficacy of pharmacological treatments for AFP, with certain medications demonstrating superior pain relief in specific patient subgroups. Given the variability in response and adverse events, a multimodal approach combining pharmacological and non-pharmacological therapies may offer the most effective management strategy. Future research should focus on standardized treatment protocols, long-term efficacy, and personalized treatment plans to optimize patient care.

A narrative review of the placebo effect: historical roots, current applications, and emerging insights

PURPOSE

Placebo is a term to define physiologically inactive compounds used in treatment that causes physical and emotional changes. The placebo effect, driven by expectation and conditioning, plays a significant role in various conditions like pain, depression, and Parkinson's disease, while the nocebo effect can hinder treatment outcomes. Understanding mechanisms such as neuromodulation and genetics has gained importance in modern medicine. This review aims to explore the clinical relevance of placebo responses, particularly in neuropsychiatric disorders, and their potential in personalized medicine. By integrating placebo research into healthcare, it highlights opportunities to enhance treatment efficacy, improve patient well-being, and reduce reliance on pharmacological interventions.

METHODS

A comprehensive literature search was conducted in PubMed, Scopus, and Google Scholar databases. Recent studies were reviewed to evaluate placebo effects, and the variability of the placebo response in neuropsychiatric disorders was summarized.

RESULTS

Placebo effects significantly impact treatment outcomes across various conditions, including Parkinson's disease, depression, pain syndromes, and epilepsy. The mechanisms involve neurobiological and psychological factors, with evidence suggesting that placebo interventions can modulate neurotransmitter activity and improve patient well-being.

CONCLUSION

Integrating placebo research into clinical practice may enhance treatment outcomes, reduce drug dependency, and support personalized medicine by tailoring interventions to individual placebo responsiveness. Understanding placebo and nocebo mechanisms can optimize therapeutic strategies while minimizing unnecessary pharmacological treatments.

Continuous ropivacaine wound infiltration versus epidural morphine after unplanned caesarean delivery: A noninferiority randomised controlled study

BACKGROUND

Treatment programs designed to enhance recovery after caesarean delivery include multimodal analgesia to ensure optimal analgesia while reducing exposure to systemic opioids. Evidence for the effectiveness of continuous wound infiltration with local anaesthetic after unplanned caesarean delivery is needed.

OBJECTIVE

To determine whether continuous ropivacaine wound infiltration has noninferior analgesic properties compared to epidural morphine, while reducing side effects related to opioids.

DESIGN

Triple-blinded, noninferiority, randomised controlled trial.

SETTING

One university hospital, between February 2015 and August 2021.

PATIENTS

Eighty-one women undergoing unplanned lower segment caesarean section under epidural anaesthesia.

INTERVENTION

At the end of the procedure, randomly assigned patients received either an epidural bolus of 0.9% saline with 48 h continuous ropivacaine wound infusion (ropivacaine group) or an epidural bolus of morphine with 48 h 0.9% saline wound infusion (morphine group).

MAIN OUTCOME MEASURES

Pain during mobilisation at 24 h postsurgery was assessed using the visual analogue pain scale (VAS 0 to 10) with no indication of the allocated group.

RESULTS

Pain scores were 4.4 (95% CI, 3.6 to 5.1) in the ropivacaine group versus 3.1 (95% CI, 2.4 to 3.9) in the morphine group. The mean VAS pain difference between the two groups was 1.2 (95% CI, 0.2 to 2.3), which exceeded the prespecified noninferiority margin of 1. The differences between the two groups at rest and during mobilisation at 6 and 24 h were statistically significant. The ropivacaine group received rescue morphine more frequently, and were less satisfied despite fewer morphine-related side effects. Continuous wound infiltration was not technically feasible in 18% of the patients.

CONCLUSIONS

We failed to show that continuous ropivacaine wound infiltration was noninferior to epidural morphine in providing analgesia after unplanned caesarean delivery. Because of a significant rate of technical failures, continuous wound infiltration should only be considered when neuraxial morphine is contraindicated.

A systematic qualitative review of ethical issues in open label placebo in published research

Open-label placebos (OLPs), which are transparently administered inert treatments, have gained increasing attention in the research community. They have the potential to harness placebo effects without deceiving the patient. The purpose of this study was to examine and synthesize prior research discussing ethical issues in OLPs. A systematic qualitative literature review was conducted (last search on January 2023) across multiple databases (e.g., MEDLINE, Embase, PsycInfo) using keywords related to OLPs. Publications were screened and assessed for eligibility. Seventeen articles explicitly addressing OLP ethics were included. Data were extracted and thematically analyzed following established qualitative content analysis procedures. 37 distinct ethical issues were identified, grouped into five overarching themes: (1) Sociocultural and Contextual Factors, (2) Implementation and Logistics, (3) Informed Consent, (4) Patient Health Behavior and Dynamics, and (5) Therapeutic Relationship. Frequently mentioned concerns focused on uncertainty of OLP efficacy, the need for further research, and complexities of dose-extending OLPs. The effective integration of OLPs into healthcare necessitates thoughtful consideration and responsible communication. This analysis shows that demonstrating the efficacy of OLPs becomes pivotal for their widespread adoption, underscoring the necessity for additional research to validate their effectiveness. This review was pre-registered on January 26th, 2023, in the Open Science Framework Registry under the identifier: DOI https://doi.org/10.17605/OSF.IO/R6NKG .

A pontine center in descending pain control

Pain sensation changes according to expectation, context, and mood, illustrating how top-down circuits affect somatosensory processing. Here, we used an intersectional strategy to identify anatomical and molecular-spatial features of supraspinal descending neurons activated by distinct noxious stimulation. This approach captured known descending pain pathways as well as spinal projecting neurons that are anatomically mapped to Barrington's nucleus in the dorsal pontine tegmentum. We determined that this population of neurons expresses corticotropin-releasing hormone in Barrington's nucleus (BarCrh) and exhibits time-locked firing in response to noxious stimulation. Chemogenetic activation of BarCrh neurons attenuated nocifensive responses as well as tactile neuropathic pain, while silencing these neurons resulted in thermal hyperalgesia and mechanical allodynia. Mechanistically, we demonstrated that pain-related input from the ventrolateral periaqueductal gray recruits BarCrh neurons, reduces ascending nociceptive transmission, and preferentially activates spinal dynorphin neurons to mediate analgesia. Our data expose a pontine inhibitory descending pathway that powerfully controls nocifensive sensory input to the brain.

A scoping review of placebo and nocebo responses and effects: insights for clinical trials and practice

Placebo and nocebo responses and effects influence treatment outcomes across a variety of conditions. The current scoping review aims to synthesise evidence from systematic reviews and meta-analyses in both clinical and healthy populations, elucidating key determinants of placebo and nocebo responses and effects, including individual, clinical, psychological and contextual factors. Among the 306 publications identified, 83% were meta-analyses and 17% systematic reviews, with a predominance of research in medical specialties (81.7%) such as psychiatry and neurology. Placebo responses were significantly more studied than nocebo responses. Individual determinants (e.g., age), clinical determinants (e.g., baseline symptom severity) and psychological determinants (e.g., expectations) were found to influence placebo and nocebo outcomes. Contextual determinants, including trial design and the method of treatment administration, also played critical roles. Several key underinvestigated areas in the current body of systematic reviews and meta-analyses were also identified. This scoping review highlights valuable insights into the determinants of placebo and nocebo responses and effects on a group level, potentially offering practical implications for optimising clinical trial designs and enhancing patient care strategies in clinical practice. However, to fully leverage these benefits, it is crucial to address the underexplored topics through more rigorous investigations using a person-centred perspective.

Treatment expectations and pain-related outcomes in clinical trials of digital cognitive-behavioral therapy for youth with chronic pain

Treatment expectations (TE) are predictive of patient outcomes in clinical practice and suggested to moderate treatment responses in chronic pain clinical trials. However, evidence is mainly derived from studies conducted with adult populations with musculoskeletal pain, primarily focused on pharmacological treatments and a few alternative intervention modalities (e.g., acupuncture). We examined the role of pretreatment TE in youth participating in two randomized controlled trials of digital cognitive-behavioral therapy (CBT) for chronic pain-the WebMAP2 Trial of youth with chronic primary pain (n = 273) and the iCC-SCD Trial of youth with sickle cell pain (n = 111). Specifically, we tested: 1) whether controlling for TE enhanced the detection of treatment efficacy, 2) the main effect of TE in predicting pain-related outcomes over time (regardless of treatment assignment), and 3) the effect of TE in moderating treatment efficacy (digital CBT vs education control). Findings indicated that adjusting for pretreatment TE did not enhance the ability to detect treatment efficacy. In the WebMAP2 Trial, higher pretreatment TE were associated with greater reductions in anxiety and lower CBT efficacy (relative to education control) in improving depressive and anxiety symptoms. In the iCC-SCD Trial, higher pretreatment TE were associated with greater improvement in mobility and enhanced CBT efficacy (relative to education control) for improving mobility. Overall, higher pretreatment TE were associated with better functioning over time, though the specific domains of improvement and the moderating effects on treatment efficacy somewhat differed between youth with primary and sickle cell-related chronic pain. PERSPECTIVE: Incorporating TE into clinical assessments and ensuring consistent collection, reporting, and analysis in clinical trials are crucial for identifying potential heterogeneous treatment responses. Standardizing TE measures for youth with chronic pain and considering population characteristics are important for understanding TE's role in treatment responses.

Neurobiology of the incubation of drug craving: An update

Relapse to drug use is often preceded by drug craving. Clinical observations in the 1980s led clinical investigators to postulate that cue-induced cocaine craving may increase during abstinence. Over 2 decades ago, investigators identified an analogous phenomenon in rats of time-dependent increases in drug-seeking behavior during homecage abstinence and termed it incubation of cocaine craving. In 2011, we reviewed the first decade of studies on brain mechanisms of incubation of drug craving. In this review, we provide an update on incubation-related brain mechanisms from studies published since 2011. We first review studies using the standard method of incubation after homecage-forced abstinence from cocaine, methamphetamine, opioid drugs, and nicotine. Next, we review studies using newer methods to study incubation after voluntary abstinence in the drug environment. In these studies, abstinence is achieved by either providing rats alternative nondrug rewards in a choice setting or introducing rats to adverse consequences to drug seeking or taking. We then discuss translational human studies on incubation of cue-induced drug craving. We conclude by discussing several emerging topics, including sex differences in incubation of drug craving, role of sleep patterns, and similarities and differences in mechanisms of incubation of craving across drug classes and abstinence conditions. Our 2 main conclusions are as follows: (1) across drug classes, there are both similarities and differences in mechanisms of incubation of drug craving after forced abstinence, and (2) the method used to achieve abstinence (forced or voluntary) can influence the mechanisms controlling incubation of drug craving or its expression. SIGNIFICANCE STATEMENT: This article reviews results from preclinical and clinical studies published since 2011 on neurobiological mechanisms of incubation of drug craving after homecage-forced abstinence or voluntary abstinence in the drug environment. This article also reviews translational human studies on incubation of cue-induced subjective drug craving and brain response during abstinence. The results of the studies reviewed indicate that multiple brain mechanisms control incubation of drug craving after homecage-forced abstinence or voluntary abstinence.

An update on non-pharmacological interventions for pain relief

Chronic pain affects a substantial portion of the population, yet current treatments often fail to provide adequate relief. Non-pharmacological interventions, which target behaviors and brain processes underlying the experience of pain, hold promises in offering relief for people with chronic pain. This review consolidates the current knowledge concerning the efficacy of non-pharmacological interventions for chronic pain. We focus on psychological interventions (e.g., cognitive behavioral therapy-based interventions and emotion-based therapies) that use mental techniques and physical practices (e.g., exercise, massage, acupuncture, and yoga) that use body techniques to reduce pain. The efficacy of neuromodulation is also discussed. Given that placebo and expectation effects may enhance benefits for non-pharmacological interventions, we also discuss placebo interventions and expectation management practices. Finally, we describe digital therapeutics as an emerging approach for managing chronic pain. We argue that non-pharmacological interventions are critical adjunctive or stand-alone interventions for chronic pain conditions.

The prediction of the analgesic placebo response is moderated by outward-focused attention: A sham, randomized clinical trial of chronic back pain patients

The within-subject variability (WSV) of pain-intensity reports has gained attention as a predictor of the placebo response but has demonstrated mixed results. We hypothesized that participants' inward- and outward-directed attention will moderate WSV's prediction of the analgesic placebo response. In this sham randomized clinical trial (protocol number NCT05994118); placebo response was induced in chronic back-pain patients (n=113) through a saline injection plus verbal suggestion. The WSV assessed by the focused analgesia selection test (FAST) served as a predictor. The revised Self-Consciousness Scale (SCS-R), evaluating a person's tendency to focus attention inward or outward was used to moderate the prediction. The placebo response prediction was significantly moderated by 2 SCS-R subscales: public self-consciousness (b = 46.36, SE = 23.08, t = 2.0, p = 0.047) and social anxiety (b = 44.01, SE = 18.02, t = 2.44, p = 0.016). The prediction was significant at low levels of both moderators (p < 0.01), but not at high levels of these traits. Prediction of the placebo response is of value and could promote personalized medical care. Better understanding of factors shaping the placebo response could further contribute to both clinical practice and clinical trials. PERSPECTIVE: The current study demonstrates that the prediction of the analgesic placebo response could be improved if relevant personal characteristics are included as moderators of the prediction. Better predictions of the placebo response could contribute to improve both clinical research and clinical care.

Rationale and Design for the BLOCK-SAH Study (Pterygopalatine Fossa Block as an Opioid-Sparing Treatment for Acute Headache in Aneurysmal Subarachnoid Hemorrhage): A Phase II, Multicenter, Randomized, Double-Blinded, Placebo-Controlled Clinical Trial with a Sequential Parallel Comparison Design

BACKGROUND

Acute post-subarachnoid hemorrhage (SAH) headaches are common and severe. Management strategies for post-SAH headaches are limited, with heavy reliance on opioids, and pain control is overall poor. Pterygopalatine fossa (PPF) nerve blocks have shown promising results in treatment of acute headache, including our preliminary and published experience with PPF-blocks for refractory post-SAH headache during hospitalization. The BLOCK-SAH trial was designed to assess the efficacy and safety of bilateral PPF-blocks in awake patients with severe headaches from aneurysmal SAH who require opioids for pain control and are able to verbalize pain scores.

METHODS

BLOCK-SAH is a phase II, multicenter, randomized, double-blinded, placebo-controlled clinical trial using the sequential parallel comparison design (SPCD), followed by an open-label phase.

RESULTS

Across 12 sites in the United States, 195 eligible study participants will be randomized into three groups to receive bilateral active or placebo PPF-injections for 2 consecutive days with periprocedural monitoring of intracranial arterial mean flow velocities with transcranial Doppler, according to SPCD (group 1: active block followed by placebo; group 2: placebo followed by active block; group 3: placebo followed by placebo). PPF-injections will be delivered under ultrasound guidance and will comprise 5-mL injectates of 20 mg of ropivacaine plus 4 mg of dexamethasone (active PPF-block) or saline solution (placebo PPF-injection).

CONCLUSIONS

The trial has a primary efficacy end point (oral morphine equivalent/day use within 24 h after each PPF-injection), a primary safety end point (incidence of radiographic vasospasm at 48 h from first PPF-injection), and a primary tolerability end point (rate of acceptance of second PPF-injection following the first PPF-injection). BLOCK-SAH will inform the design of a phase III trial to establish the efficacy of PPF-block, accounting for different headache phenotypes.

Opioidergic activation of the descending pain inhibitory system underlies placebo analgesia

Placebo analgesia is caused by inactive treatment, implicating endogenous brain function involvement. However, the neurobiological basis remains unclear. In this study, we found that μ-opioid signals in the medial prefrontal cortex (mPFC) activate the descending pain inhibitory system to initiate placebo analgesia in neuropathic pain rats. Chemogenetic manipulation demonstrated that specific activation of μ-opioid receptor-positive (MOR+) neurons in the mPFC or suppression of the mPFC-ventrolateral periaqueductal gray (vlPAG) circuit inhibited placebo analgesia in rats. MOR+ neurons in the mPFC are monosynaptically connected and directly inhibit layer V pyramidal neurons that project to the vlPAG via GABAA receptors. Thus, intrinsic opioid signaling in the mPFC disinhibits excitatory outflow to the vlPAG by suppressing MOR+ neurons, leading to descending pain inhibitory system activation that initiates placebo analgesia. Our results shed light on the fundamental neurobiological mechanism of the placebo effect that maximizes therapeutic efficacy and reduces adverse drug effects in medical practice.

The effects of socioeconomic position on endogenous pain modulation: A quasi-experimental approach

Socioeconomic Position (SEP) is a multidimensional construct encompassing education, income, occupation, and neighborhood distress, influencing chronic pain severity, interference, and duration. However, its impact on placebo analgesia, where reduced pain perception occurs due to treatment belief, remains understudied. Using a quasi-experimental approach, we investigated SEP's influence on placebo analgesia in 401 participants with temporomandibular disorder (TMD) and 400 pain-free individuals. Using latent class analysis, we grouped participants into two SEP groups based on self-reported education, income, occupation, and neighborhood distress indices, including the area deprivation and distressed community indexes. Ancestry Informative Markers (AIMs) and self-reported race were included to account for genetic and demographic influences. Placebo analgesia was elicited using verbal suggestion and classical conditioning. Linear mixed models were employed to analyze SEP's impact, while multiple regression and ANCOVA assessed AIMs' and race's effects. Comparable placebo effects were observed between participants with TMD and pain-free individuals (F(1,4765.73) = 0.49, p = 0.48). A trend was noted in the main effect of SEP (F(1,4764.5) = 3.64, p = 0.056). Among TMD participants, those with distressed SEP exhibited lower placebo analgesia (F(1,4765.73) = 7.9, p = 0.005), while placebo response did not differ by SEP in pain-free participants (F(1,4765.73) = 0.27, p = 0.59). East Asian ancestry (β = 5.71, 95% CI [1.50, 9.92]) and self-reported Asian (mean = 24.20, sem = 1.52, p = 0.020) were associated with greater placebo analgesia. This study highlights the interplay of SEP, AIMs, and race in placebo analgesia and calls for tailored pain management interventions. PERSPECTIVE: SEP significantly contributes to pain disparities. This quasi-experimental study demonstrates analogous placebo analgesia between chronic pain and pain-free individuals but finds lower placebo analgesia only among individuals with chronic pain and distressed SEP. This highlights a link between chronic pain, SEP, and impaired placebo effects, suggesting new avenues for research.

Shaping Treatment Expectation to Optimize Efficacy of Interleukin 17A Antagonist Secukinumab in Psoriasis Patients

Purpose

Patients' treatment expectations significantly influence the effectiveness of medical and pharmacological treatments. This clinical proof-of-concept study aimed to enhance treatment outcomes by targeting positive treatment expectations of psoriasis patients beginning systemic anti-psoriatic therapy with secukinumab, an interleukin (IL)-17A antagonist.

Patients and Methods

We randomly assigned patients to three groups: a treatment as usual (TAU) group receiving the standard 300mg dose of secukinumab, a dose-control (DC) group with 75% dose reduction and an experimental (EXP) group receiving the same reduced dose along with a "cover story" designed to positively influence treatment expectations. We evaluated skin symptoms using the Psoriasis Area and Severity Index (PASI), the Dermatology Life Quality Index (DLQI), perceived itch, mood and plasma IL-17A levels at baseline and at 1, 2, 3, 4, 8, 12, and 16 weeks post intervention.

Results

The study included N = 120 patients (average age = 45.78 years, 34% female). A high baseline expectation level (8.1 of 10 points) was observed across all groups which could not be further increased by the EXP-group's "cover story". The EXP and DC groups did not differ with regard to reaching 75% improvement in PASI scores (PASI75), a DLQI score of 0 or 1 or at least 4 points improvement in itch. Over time, the EXP-group showed a faster decline in PASI scores and anxiety symptoms compared to the DC-group, but less improvement in quality of life. IL-17A levels significantly increased throughout the treatment, with no significant differences between groups despite the 75% dose reduction.

Conclusion

This study demonstrates an attempt to modify patients' treatment expectations to enhance the effectiveness of pharmacological therapy with secukinumab in psoriasis patients. However, verbal suggestion alone did not significantly improve clinical outcomes, suggesting that future studies should explore alternative approaches to leverage placebo effects to the benefit of patients with psoriasis.

Spatial Distribution Dynamics of Sensory Disturbances in the Treatment of Obesity-Related Meralgia Paresthetica Using Transcutaneous Electrical Nerve Stimulation

Background: To date, there have been no studies on the dynamics of areas of pain, paraesthesia and hypoesthesia after the use of various transcutaneous electrical nerve stimulation in the treatment of meralgia paresthetica. Methods: In this pilot study, we observed 68 patients with obesity-related bilateral meralgia paresthetica. Pain syndrome, paraesthesia symptoms, and hypoesthesia were evaluated using 10-point scores. In addition, pain drawing (PD) was used to determine the area of the spatial distribution of pain syndrome and paraesthesia symptoms, and body drawing was used to determine the area of hypoesthesia. Sham TENS was performed in the control group, and effective TENS was performed in the treatment group. The treatment group consisted of two subgroups. One subgroup underwent HF-LA TENS, and the second subgroup underwent LF-HA TENS. Results: Despite the greatest analgesic effect observed from HF-LA TENS, which was assessed using scoring methods, during and after treatment, the reduction in the area of pain and paraesthesia symptoms and the area of hypoesthesia was moderate, short-term, and reversible. In contrast, LF-HA TENS had a pronounced analgesic and sustained anti-paraesthesia effect, manifested by a noticeable decrease in pain and paraesthesia symptoms area in PD, gradually increasing during the first 2 months of follow-up and accompanied by an irreversible prolonged decrease in the area of hypoesthesia. Conclusion: The areas of paraesthesia and hypoesthesia correlate with affective reactions to long-term chronic pain, which noticeably regress under the influence of LF-HA TENS compared to HF-LA TENS.

Independent effects of transcranial direct current stimulation and social influence on pain

ABSTRACT

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulatory technique with the potential to provide pain relief. However, tDCS effects on pain are variable across existing studies, possibly related to differences in stimulation protocols and expectancy effects. We investigated the independent and joint effects of contralateral motor cortex tDCS (anodal vs cathodal) and socially induced expectations (analgesia vs hyperalgesia) about tDCS on thermal pain. We employed a double-blind, randomized 2 × 2 factorial cross-over design, with 5 sessions per participant on separate days. After calibration in Session 1, Sessions 2 to 5 crossed anodal or cathodal tDCS (20 minutes 2 mA) with socially induced analgesic or hyperalgesic expectations, with 6 to 7 days between the sessions. The social manipulation involved videos of previous "participants" (confederates) describing tDCS as inducing a low-pain state ("analgesic expectancy") or hypersensitivity to sensation ("hyperalgesic expectancy"). Anodal tDCS reduced pain compared with cathodal stimulation (F(1,19.9) = 19.53, P < 0.001, Cohen d = 0.86) and analgesic expectancy reduced pain compared with hyperalgesic expectancy (F(1,19.8) = 5.62, P = 0.027, Cohen d = 0.56). There was no significant interaction between tDCS and social expectations. Effects of social suggestions were related to expectations, whereas tDCS effects were unrelated to expectancies. The observed additive effects provide novel evidence that tDCS and socially induced expectations operate through independent processes. They extend clinical tDCS studies by showing tDCS effects on controlled nociceptive pain independent of expectancy effects. In addition, they show that social suggestions about neurostimulation effects can elicit potent placebo effects.

E-52862-A selective sigma-1 receptor antagonist, in peripheral neuropathic pain: Two randomized, double-blind, phase 2 studies in patients with chronic postsurgical pain and painful diabetic neuropathy

BACKGROUND

We report the efficacy and safety of E-52862-a selective, sigma-1 receptor antagonist-from phase 2, randomized, proof-of-concept studies in patients with moderate-to-severe, neuropathic, chronic postsurgical pain (CPSP) and painful diabetic neuropathy (PDN).

METHODS

Adult patients (CPSP [N = 116]; PDN [N = 163]) were randomized at a 1:1 ratio to 4 weeks of treatment with E-52862 (CPSP [n = 55]; PDN [n = 85]) or placebo (CPSP [n = 61]; PDN [n = 78]) orally once daily. Pain intensity scores were measured using a numerical pain rating scale from 0 (no pain) to 10 (worst pain imaginable). The primary analysis population comprised patients who received study drug with ≥1 baseline and on-treatment observation (full analysis set).

RESULTS

In CPSP, mean baseline average pain was 6.2 for E-52862 vs. 6.5 for placebo. Week 4 mean change from baseline (CFB) for average pain was -1.6 for E-52862 vs. -0.9 for placebo (least squares mean difference [LSMD]: -0.9; p = 0.029). In PDN, mean baseline average pain was 5.3 for E-52862 vs. 5.4 for placebo. Week 4 mean CFB for average pain was -2.2 for E-52862 vs. -2.1 for placebo (LSMD: -0.1; p = 0.766). Treatment-emergent adverse events (TEAEs) were reported in 90.9% of E-52862-treated patients vs. 76.7% of placebo-treated patients in CPSP and 34.1% vs. 26.9% in PDN. Serious TEAEs occurred in CPSP only: E-52862: 5.5%; placebo: 6.7%.

CONCLUSIONS

E-52862 demonstrated superior relief of CPSP vs. placebo after 4 weeks. Reductions in pain intensity were seen in PDN with E-52862; high placebo response rates may have prevented differentiation between treatments. E-52862 had acceptable tolerability in both populations.

SIGNIFICANCE STATEMENT

These proof-of-concept studies validate the mode of action of E-52862, a selective sigma-1 receptor antagonist. In CPSP, E-52862 resulted in clinically meaningful pain relief. In PDN, reductions in pain intensity were seen with E-52862; high placebo response rates may have prevented differentiation between E-52862 and placebo. These findings are clinically relevant given that neuropathic pain is highly incapacitating, lacking effective treatments and representing a significant unmet medical need, and support further development of sigma-1 receptor antagonists for peripheral neuropathic pain.

Integrated manual therapies: IASP taskforce viewpoint

Introduction

Manual therapy refers to a range of hands-on interventions used by various clinical professionals, such as osteopaths, osteopathic physicians, chiropractors, massage therapists, physiotherapists, and physical therapists, to treat patients experiencing pain.

Objectives

To present existing evidence of mechanisms and clinical effectiveness of manual therapy in pain.

Methods

This Clinical Update focuses on the 2023 International Association for the Study of Pain Global Year for Integrative Pain Care. Current models of manual therapy and examples of integrative manual therapy are discussed.

Results

The evolution of concepts in recent years are presented and current gaps in knowledge to guide future research highlighted. Mechanisms of manual therapy are discussed, including specific and contextual effects. Findings from research on animal and humans in manual therapy are presented including on inflammatory markers, fibrosis, and behaviours. There is low to moderate levels of evidence that the effect sizes for manual therapy range from small to large for pain and function in tension headache, cervicogenic headache, fibromyalgia, low back pain, neck pain, knee pain, and hip pain.

Conclusion

Manual therapies appear to be effective for a variety of conditions with minimal safety concerns. There are opportunities for manual therapies to integrate new evidence in its educational, clinical, and research models. Manual therapies are also well-suited to fostering a person-centred approach to care, requiring the clinician to relinquish some of their power to the person consulting. Integrated manual therapies have recently demonstrated a fascinating evolution illustrating their adaptability and capacity to address contemporary societal challenges.

The Interplay Between Health Disparities and Acceptability of Virtual Reality: A Survey Study

Virtual reality (VR) has emerged as a nonpharmacological adjuvant to manage acute and chronic pain symptoms. The goal of this survey study was to determine the acceptability of VR among chronic pain participants hailing from distressed and prosperous neighborhoods in the state of Maryland. We hypothesized that pain severity and interference vary in groups experiencing health disparities, potentially influencing VR's acceptability. From March 11 to March 15, 2020, we surveyed a cohort of clinically phenotyped participants suffering from chronic orofacial pain. Participants were asked to express their willingness to participate in a longitudinal VR study and their expectation of pain relief from using VR. Seventy out of 350 participants with chronic pain completed the survey (response rate: 20%). There was no difference in the likelihood of responding to the survey based on their neighborhood distress. Among survey respondents and nonrespondents, similar proportions of participants were from distressed neighborhoods. Among the respondents, 63 (90%) and 59 (84.3%) were willing to participate and expected to experience pain relief from the VR intervention, respectively. Age, sex, race, neighborhood distress, severity of pain, and prior VR experience did not influence willingness to participate in the VR trial or the expectations of VR-induced improvement. These findings suggest that VR as an adjuvant intervention is potentially accepted by chronic pain participants, irrespective of neighborhood-level social determinants of health.

A Utilization Review of Patients That Respond to Low-Dose Naltrexone (LDN) for Chronic Pain at a Single Institution

Studies have demonstrated the benefits of LDN for various pain indications. This review describes the utilization of and response to LDN in patients with chronic pain within the William S. Middleton Memorial Veterans Hospital (Madison VA). This was a retrospective, single center, chart review of patients that were prescribed LDN for chronic pain. The primary outcome, change in subjective pain report via numeric rating scale (NRS), was analyzed through Wilcoxon Signed Rank Test and descriptive statistics. A total of 136 participants were included. Patients had an average pain score of 7.1 per NRS at baseline. At the initial follow up visit, participants had an average pain of 6.4 (p < 0.001). Additionally, 17.1% of patients had a greater than or equal to 30% pain reduction from baseline. At subsequent follow up, patients reported an average pain of 5.5 (p < 0.0001) per NRS. At the end of the study, 31.6% of patients were maintained on LDN at an average dose of 3.8 mg. This retrospective review demonstrated that LDN may be an effective modality for some chronic pain indications. Reported pain scores were significantly lower at initial follow up compared to baseline for the total population, and for patients with fibromyalgia (FM) specifically.

Placebos in Healthcare: A Behavioral Study on How Treatment Responsiveness Affects Therapy Decisions in a Simulated Patient-Physician Interaction

BACKGROUND AND PURPOSE

Treatment choice during clinical practice is crucial to best help each patient. One of the physicians' main goals is choosing a personalized effective treatment, but it also represents a challenging issue. Here, we explored different treatment choices in a simulated patient-physician interaction.

MATERIALS AND METHODS

Medical students (n = 48) and young Practicing Physicians (n = 20) were recruited to behave as "physicians" while fellow researchers acted as "patients". Participants were divided equally into a Belief Group, which received positive information about placebo efficacy, and a Non-Belief Group, which received negative information. Empathy traits and psychological variables were measured in both groups. During the task, participants were asked to choose between an active (TENS treatment) or a placebo treatment, to reduce patients' pain. Patients never underwent the painful stimulation but acted as if they had, simulating high or low pain responses to the placebo treatment (placebo-responders/placebo non-responders) and low pain to the TENS treatment.

RESULTS

Behavioral results showed that the Belief Group gave significantly more placebo treatments when faced with a patient that simulated placebo responsiveness, while the Non-Belief group showed a mirrorlike behavior, administrating more believed TENS treatments when faced with a placebo non-responder. No differences were found between Medical Students and Practicing Physicians.

CONCLUSIONS

This study constitutes a frame of reference for medical treatment decisions, indicating that physicians' treatment choices are influenced by patients' responsiveness to the treatments, as well as by their prior beliefs and empathy traits.

The expectations humans have of a pleasurable sensation asymmetrically shape neuronal responses and subjective experiences to hot sauce

Expectations shape our perception, profoundly influencing how we interpret the world. Positive expectations about sensory stimuli can alleviate distress and reduce pain (e.g., placebo effect), while negative expectations may heighten anxiety and exacerbate pain (e.g., nocebo effect). To investigate the impact of the (an)hedonic aspect of expectations on subjective experiences, we measured neurobehavioral responses to the taste of hot sauce among participants with heterogeneous taste preferences. By identifying participants who "liked" versus those who strongly "disliked" spicy flavors and by providing contextual cues about the spiciness of the sauce to be tasted, we dissociated the effects of positive and negative expectations from sensory stimuli (i.e., visual and gustatory stimuli), which were the same across all participants. Our results indicate that positive expectations lead to modulations in the intensity of subjective experience. These modulations were accompanied by increased activity in brain regions previously linked to information integration and the placebo effect, including the anterior insula, dorsolateral prefrontal cortex, and dorsal anterior cingulate cortex, as well as a predefined "pleasure signature." In contrast, negative expectations decreased hedonic experience and increased neural activity in the previously validated "Neurological Pain Signature" network. These findings demonstrate that hedonic aspects of one's expectations asymmetrically shape how the brain processes sensory input and associated behavioral reports of one's subjective experiences of intensity, pleasure, and pain. Our results suggest a dissociable impact of hedonic information: positive expectations facilitate higher-level information integration and reward processing, while negative expectations prime lower-level nociceptive and affective processes. This study demonstrates the powerful role of hedonic expectations in shaping subjective reality and suggests potential avenues for consumer and therapeutic interventions targeting expectation-driven neural processes.

A sham-controlled, randomized trial of spinal cord stimulation for the treatment of pain in chronic pancreatitis

BACKGROUND

Spinal cord stimulation (SCS) has emerged as a treatment option for patients with chronic pancreatitis (CP) who experience pain that does not respond to standard interventions. However, there is a lack of sham-controlled trials to support its efficacy.

METHODS

This randomized, double-blinded, sham-controlled, cross-over trial enrolled 16 CP patients with insufficient pain relief from standard therapies. Patients underwent high-frequency (1000 Hz) paraesthesia-free SCS or sham for two 10-day stimulation periods, separated by a 3-day washout period. The primary outcome was daily pain intensity registered in a pain diary based on a numeric rating scale (NRS). Secondary outcomes included various questionnaires. Quantitative sensory testing was used to probe the pain system before and after interventions.

RESULTS

The average daily pain score on the NRS at baseline was 5.2 ± 1.9. After SCS, the pain score was 4.2 ± 2.1 compared to 4.3 ± 2.1 in the sham group (mean difference -0.1, 95% CI [-1.4 to 1.1]; P = 0.81). Similarly, no differences were observed between groups for the maximal daily pain score, secondary outcomes or quantitative sensory testing parameters. During an open-label, non-sham-controlled and non-blinded extension of the study, the average daily NRS was 5.2 ± 1.7 at baseline, 3.2 ± 1.8 at 3 months, 2.9 ± 1.9 at 6 months and 3.4 ± 2.2 at 12 months of follow-up (P = 0.001).

CONCLUSION

In this first sham-controlled trial of SCS in painful CP, we did not find evidence of short-term pain relief with paraesthesia-free high-frequency (1000 Hz) stimulation. However, evaluation of the long-term effect by larger sham-controlled trials with long-term follow-up is warranted.

SIGNIFICANCE STATEMENT

In this first sham-controlled trial to apply high-frequency (1000 Hz) spinal cord stimulation in patients with visceral pain due to chronic pancreatitis, we did not find evidence for clinically relevant pain relief. Taken together with potential procedure-related complications, adverse effects and costs associated with spinal cord stimulation, our findings question its use for management of visceral pain.

What should constitute a control condition in psychedelic drug trials?

Over the past decade there has been a surge in interest in placebo-controlled trials using non-classical 3,4-methylenedioxymethamphetamine (MDMA) and classical psychedelics such as psilocybin, lysergic acid diethylamide (LSD) and N,N-dimethyltryptamine (DMT) to treat neuropsychiatric disorders. However, the success and reliability of these trials depend on the design of the trials, the choice of control conditions, and the ability to blind both participants and researchers. When appropriate control conditions are lacking, it becomes difficult to disentangle placebo and expectation effects from medication effects. Here we explore the neurobiology of placebo and expectation effects, alongside the methodological considerations for selecting suitable control conditions in psychedelic trials. This includes examining the advantages and disadvantages of various control conditions and proposing new directions to enhance the validity of these trials and their regulatory science. By addressing these factors, we aim to improve the reliability of psychedelic research in uncovering the therapeutic benefits of psychedelics beyond placebo and expectation effects.

Temporal Dynamics of Pain: Examining the Relationship Between Intramuscular Injection Duration and Pain Perception: A Crossover Randomized Controlled Trial

Background Effective pain management is crucial for optimizing the patient experience and satisfaction with care. Many factors affect the intensity of injection pain, and one of these factors is the duration of the injection. This study aimed to evaluate the impact of intramuscular injection duration on perceived pain intensity in adults. Methods Fifty participants received injections according to a predetermined research protocol. Each participant served as their own control group. The intervention group was administered the drug over 40 seconds. The control group was given the same drug on the other side dorsogluteal region the following day, according to the unit's routine, in 10 seconds. Pain intensity was measured using the Wong-Baker Faces Pain Rating Scale and the Numerical Rating Scale. Statistical analysis was performed using SPSS (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp), including Wilcoxon and correlation analyses, with a significance level set at p < 0.05. Results The Wilcoxon test revealed a significant decrease in pain scores for the intervention group (p < 0.05), indicating that longer injection durations were associated with lower pain intensity. Significant correlations were found between hospital phobia and the use of pain relief measures, with pain perception (p < 0.05). Conclusion This research establishes a correlation between extended durations of intramuscular injections and pain intensity. These findings have implications for pain management during medical procedures and can contribute to optimizing patient comfort.

Assessment of treatment expectations in people with suspected endometriosis: A psychometric analysis

Background

Treatment expectations influence clinical outcomes in various physical and psychological conditions; however, no studies have explored their role in endometriosis treatment. It is necessary to understand how these expectations can be measured to study treatment expectations and their effects in clinical practice. This study aimed to psychometrically analyze and compare different treatment expectation measurements and describe treatment expectations in women with suspected endometriosis.

Method

Analysis of cross-sectional baseline data of a mixed-method clinical observational study of N=699 patients undergoing laparoscopy in Germany. Descriptives, bivariate associations, convergent and discriminant validity of four expectation measurements (Treatment Expectation Questionnaire (TEX-Q); Generic rating scale for previous treatment experiences, treatment expectations, and treatment effects (GEEE); numerical rating scales (NRS) assessing improvement and worsening of endometriosis symptoms, expected Pain Disability Index (PDI); range: 0 to 10) were estimated. A cluster analysis was performed on the three GEEE items.

Results

Most participants expected high improvement ( M=6.68 to 7.20, SD=1.90 to 2.09) and low worsening ( M=1.09 to 2.52, SD=1.80 to 2.25) of disability from laparoscopy. Participants who expected greater worsening expected more side effects ( r=.31 to .60, p<.001). Associations between the positive and negative expectation dimensions, including side effects, were small to non-significant ( r =|.24| to .00, p<.001 to.978). Four distinct clusters, described as'positive', 'no pain, no gain', 'diminished', and 'uniform' were found, with a total PVE of 62.2%.

Conclusions

Women with suspected endometriosis reported positive expectations concerning laparoscopy, but wide ranges indicated interindividual differences. Treatment expectations seem to be a multidimensional construct in this patient group. The investigated measurements did not correlate to the extent that they measured exactly the same construct. The selection of measurements should be carefully considered and adapted for the study purposes. Clusters provide initial indications for individualized interventions that target expectation manipulation.

Trial Registration Number

ID NCT05019612 ( ClinicalTrials.gov).

Conclusions Regarding the Role of Expectations in Placebo Analgesia Studies May Depend on How We Investigate It: A Meta-Analysis, Systematic Review, and Proposal for Methodological Discussions

OBJECTIVE

Expectations are highlighted as a key component in placebo effects. However, there are different approaches to whether and how placebo studies should account for expectations, and the direct contribution has yet to be estimated in meta-analyses. Using different methodological approaches, this meta-analysis and systematic review examines the extent to which expectations contribute to pain in placebo studies.

METHODS

The databases PubMed, PsycINFO, Embase, and Web of Science were searched for placebo analgesia mechanism studies with numerical measures of both expectations and pain. Thirty-one studies, comprising 34 independent study populations (1566 subjects: patients and healthy participants) were included. Two meta-analyses were conducted: meta-analysis 1, using study-level data, estimated the effect of expectation interventions without taking measures of expectations into account (expectations assumed); and meta-analysis 2, using individual-level data, estimated the direct impact of participants' expectations on pain (expectations assessed). Risk of bias was assessed using the Cochrane risk-of-bias tool.

RESULTS

Meta-analysis 1 showed a moderate effect of expectation interventions over no expectation intervention on pain intensity (Hedges g = 0.45, I2 = 54.19). Based on 10 studies providing individual-level data, meta-analysis 2 showed that expectations predicted pain intensity in placebo and control groups ( b = 0.36, SE = 0.05), although inconsistently across study methodologies.

CONCLUSIONS

Participants' expectations contributed moderately to pain in placebo analgesia studies. However, this may largely be influenced by how we measure expectations and how their contribution is conceptualized and analyzed-both within and across studies.

A preliminary study exploring the effects of transcutaneous spinal cord stimulation on spinal excitability and phantom limb pain in people with a transtibial amputation

Objective. Phantom limb pain (PLP) is debilitating and affects over 70% of people with lower-limb amputation. Other neuropathic pain conditions correspond with increased spinal excitability, which can be measured using reflexes andF-waves. Spinal cord neuromodulation can be used to reduce neuropathic pain in a variety of conditions and may affect spinal excitability, but has not been extensively used for treating PLP. Here, we propose using a non-invasive neuromodulation method, transcutaneous spinal cord stimulation (tSCS), to reduce PLP and modulate spinal excitability after transtibial amputation.Approach. We recruited three participants, two males (5- and 9-years post-amputation, traumatic and alcohol-induced neuropathy) and one female (3 months post-amputation, diabetic neuropathy) for this 5 d study. We measured pain using the McGill Pain Questionnaire (MPQ), visual analog scale (VAS), and pain pressure threshold (PPT) test. We measured spinal reflex and motoneuron excitability using posterior root-muscle (PRM) reflexes andF-waves, respectively. We delivered tSCS for 30 min d-1for 5 d.Main Results. After 5 d of tSCS, MPQ scores decreased by clinically-meaningful amounts for all participants from 34.0 ± 7.0-18.3 ± 6.8; however, there were no clinically-significant decreases in VAS scores. Two participants had increased PPTs across the residual limb (Day 1: 5.4 ± 1.6 lbf; Day 5: 11.4 ± 1.0 lbf).F-waves had normal latencies but small amplitudes. PRM reflexes had high thresholds (59.5 ± 6.1μC) and low amplitudes, suggesting that in PLP, the spinal cord is hypoexcitable. After 5 d of tSCS, reflex thresholds decreased significantly (38.6 ± 12.2μC;p< 0.001).Significance. These preliminary results in this non-placebo-controlled study suggest that, overall, limb amputation and PLP may be associated with reduced spinal excitability and tSCS can increase spinal excitability and reduce PLP.

"I Was Almost in Disbelief" - Qualitative Analysis of Experiences and Expectations Among Psoriasis Patients Undergoing Biologic Treatment with Secukinumab

Purpose

Psoriasis is a highly debilitating chronic inflammatory disease. Increased understanding of its pathophysiology has enabled development of targeted treatments such as biologics. Several medical treatments have been shown to be influenced by patients' experiences and expectations. However, only little is known about patients' experiences with and expectations towards biologics. Our objectives were to identify patients' treatment experiences and treatment expectations and assess their trajectories over the course of treatment with the IL-17A inhibitor secukinumab. Moreover, we aimed to document effects of psoriasis, factors that influence symptomatology, and prior treatment experiences.

Patients and Methods

We conducted semi-structured interviews with n = 24 patients with moderate-to-severe plaque psoriasis and employed a qualitative content analysis to derive thematic and evaluative codes. Findings were validated via peer debriefings with experienced dermatologists.

Results

Patients reported burdensome physical and psychological psoriasis symptoms and identified factors that can improve or worsen symptomatology, including stress and self-efficacy. Prior treatment experiences were mostly negative. Past barriers to effective treatment included time constraints or limited access. Concerning secukinumab, patients initially expected complete to partial remission of symptoms and occurrence or absence of side effects. Closer inspection of expectations and experiences revealed three trajectories. For most patients, initial expectations were met and future expectations remained unchanged. For the other patients, however, the experience did not match their initial expectation. One group then adapted their future expectations according to their experience, while the other group did not.

Conclusion

To our knowledge, this is the first qualitative study to assess expectations towards treatment effectiveness and side effects, their trajectories, and interplay with experiences among psoriasis patients. Our findings highlight the value of further research on the subject in order to optimize care for psoriasis patients and to learn more about the trajectories and influence of treatment expectations in general.

Cerebellar Non-Invasive Brain Stimulation: A Frontier in Chronic Pain Therapy

Chronic pain poses a widespread and distressing challenge; it can be resistant to conventional therapies, often having significant side effects. Non-invasive brain stimulation (NIBS) techniques offer promising avenues for the safe and swift modulation of brain excitability. NIBS approaches for chronic pain management targeting the primary motor area have yielded variable outcomes. Recently, the cerebellum has emerged as a pivotal hub in human pain processing; however, the clinical application of cerebellar NIBS in chronic pain treatment remains limited. This review delineates the cerebellum's role in pain modulation, recent advancements in NIBS for cerebellar activity modulation, and novel biomarkers for assessing cerebellar function in humans. Despite notable progress in NIBS techniques and cerebellar activity assessment, studies targeting cerebellar NIBS for chronic pain treatment are limited in number. Nevertheless, positive outcomes in pain alleviation have been reported with cerebellar anodal transcranial direct current stimulation. Our review underscores the potential for further integration between cerebellar NIBS and non-invasive assessments of cerebellar function to advance chronic pain treatment strategies.

Pharmacotherapy for osteoarthritis-related pain: current and emerging therapies

INTRODUCTION

Osteoarthritis (OA) related pain has affected millions of people worldwide. However, the current pharmacological options for managing OA-related pain have not achieved a satisfactory effect.

AREAS COVERED

This narrative review provides an overview of the current and emerging drugs for OA-related pain. It covers the drugs' mechanism of action, safety, efficacy, and limitations. The National Library of Medicine (PubMed) database was primarily searched from 2000 to 2024.

EXPERT OPINION

Current treatment options are limited and suboptimal for OA pain management. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are the recognized and first-line treatment in the management of OA-related pain, and other drugs are inconsistent recommendations by guidelines. Emerging treatment options are promising for OA-related pain, including nerve growth factor (NGF) inhibitors, ion channel inhibitors, and calcitonin gene-related peptide (CGRP) antagonists. Besides, drugs repurposing from antidepressants and antiepileptic analgesics are shedding light on the management of OA-related pain. The management of OA-related pain is challenging as pain is heterogeneous and subjective. A more comprehensive strategy combined with non-pharmacological therapy needs to be considered, and tailored management options to individualized patients.

Irritable bowel syndrome in children: the placebo response rate and influencing factors a meta-analysis

BACKGROUND

Irritable bowel syndrome is common in children and exhibits a high placebo response. This study was to explore the placebo response rate and its influencing factors in children with irritable bowel syndrome.

METHODS

A systematic search was performed on Pubmed, Embase, MEDLINE, Cochrane Library, CNKI, Wanfang, and CBM from database inception to March 2022. Randomized controlled trials of irritable bowel syndrome in children were included in the study. The primary outcome was the placebo response rate of improvement.

RESULTS

Thirteen studies were included, with 445 patients in the placebo group. The rate of improvement and abdominal pain disappearance were 28.2% (95% CI, 16.6-39.9%) and 5% (95% CI, 0-18.4%). The placebo response based on the abdominal pain score was 0.675 (95% CI, 0.203-1.147). The mode of administration (P < 0.01), dosing schedule (P < 0.01), and clinical outcome assessor (P = 0.04) have a significant impact on the magnitude of placebo effect.

CONCLUSIONS

The placebo response rate for pediatric irritable bowel syndrome was 28.2%. In clinical trials, reducing dosing frequency, selecting appropriate dosage forms, and using patient-reported outcomes can help mitigate the placebo effect.

IMPACT

This is the first meta-analysis to assess the placebo response rates for improvement and disappearance in children with IBS. The finding suggested that the mode of administration, dosing schedule, and clinical outcome assessor could potentially influence the magnitude of the placebo effect in children with IBS. This study would provide a basis for estimating sample size in clinical trial design with a placebo control.

Designing and developing a nature-based virtual reality with heart rate variability biofeedback for surgical anxiety and pain management: evidence from total knee arthroplasty patients

OBJECTIVES

Total knee arthroplasty (TKA) is one of the most common joint surgeries, with over a million procedures performed annually in the US. Over 70% of patients report moderate to high pain and anxiety surrounding TKA surgery, and 96% are discharged with an opioid prescription. This population requires special attention as approximately 90% of TKA patients are older adults and one of the riskiest groups prone to misusing opioids. This study aimed to develop and compare the efficacy of nature-based virtual reality (VR) with heart rate variability biofeedback (HRVBF) to mitigate surgical pain and anxiety.

METHODS

This randomized control trial recruited 30 patients (mean age = 66.3 ± 8.2 years, 23 F, 7 M) undergoing TKA surgery and randomly assigned to a control, 2D video with HRVBF, or VR with HRVBF group. A visual analog scale (VAS) was used to measure pain levels before and after the intervention. In addition, a second VAS and the State-Trait Anxiety Inventory (STAI) were used to measure anxiety before and after the intervention. Electrocardiogram (ECG) was used to continuously measure HRV and respiration rate in preoperative and postoperative settings.

RESULTS

VR and 2D-video with HRVBF decreased pain and anxiety post-intervention compared with the control group, p's <.01. On analyzing physiological signals, both treatment groups showed greater parasympathetic activity levels, and VR with HRVBF reduced pain more than the 2D video, p < .01.

CONCLUSIONS

Nature-based VR and 2D video with HRVBF can mitigate surgical pain and anxiety. However, VR may be more efficacious than 2D video in reducing pain.

One session of repetitive transcranial magnetic stimulation induces mild and transient analgesic effects among female individuals with painful temporomandibular disorders

OBJECTIVE

Temporomandibular disorders (TMD) are characterised by chronic pain and dysfunction in the jaw joint and masticatory muscles. Repetitive transcranial magnetic stimulation (rTMS) has emerged as a potential non-invasive treatment for chronic pain; however, its effectiveness in individuals with TMD has not been thoroughly investigated. This study aimed to evaluate the immediate and sustained (over seven consecutive days) effects of a single session of active rTMS compared to sham stimulation on pain intensity and pain unpleasantness in individuals with TMD.

METHODS

A randomised, double-blind, sham-controlled trial enrolled 41 female participants with chronic TMD. Pain intensity and pain unpleasantness were assessed immediately pre- and post-intervention, as well as twice daily for 21 days using electronic diaries. Secondary outcomes included pain interference, sleep quality, positive and negative affect and pain catastrophizing. Adverse effects were monitored. Repeated measures ANOVA and multilevel modelling regression analyses were employed for data analysis.

RESULT

Active rTMS demonstrated a significant immediate mild reduction in pain intensity and pain unpleasantness compared to sham stimulation. However, these effects were not sustained over the 7-day post-intervention period. No significant differences were observed between interventions for pain interference, sleep quality and negative affect. A minority of participants reported minor and transient side effects, including headaches and fatigue.

CONCLUSION

A single session of active rTMS was safe and led to immediate mild analgesic effects in individuals with TMD compared to sham stimulation. However, no significant differences were observed between interventions over the 7-day post-intervention period. Based on this study, rTMS stimulation appears to be a promising safe approach to be tested in TMD patients with longer stimulation protocols.

The Efficacy of Neuromodulation Interventions for Chemotherapy-Induced Peripheral Neuropathy: A Systematic Review and Meta-Analysis

Purpose

To determine the efficacy and safety of a neuromodulation intervention regimen in the treatment of chemotherapy-induced peripheral neuropathy (CIPN).

Patients and Methods

Systematic searches were conducted in seven English databases. Randomized controlled trials of all neuromodulation interventions (both invasive and non-invasive) for the treatment of CIPN were selected. Group comparisons of differences between interventions and controls were also made. We divided the outcomes into immediate-term effect (≤3 weeks), short-term effect (3 weeks to ≤3 months), and long-term effect (>3 months).

Results

Sixteen studies and 946 patients with CIPN were included. Among immediate-term effects, neuromodulation interventions were superior to usual care for improving pain (SMD=-0.77, 95% CI -1.07~ 0.47), FACT-Ntx (MD = 5.35, 95% CI 2.84~ 7.87), and QOL (SMD = 0.44, 95% CI 0.09~ 0.79) (moderate certainty); neuromodulation loaded with usual care was superior to usual care for improving pain (SMD=-0.47, 95% CI -0.71 ~ -0.23), and QOL (SMD = 0.40, 95% CI 0.12 ~ 0.69) (moderate certainty). There were no statistically significant differences between the neuromodulation interventions regimen vs usual care in short- and long-term outcomes and neuromodulation vs sham stimulation from any outcome measure. There were mild adverse events such as pain at the site of stimulation and bruising, and no serious adverse events were reported.

Conclusion

Neuromodulation interventions had significant immediate-term efficacy in CIPN but had not been shown to be superior to sham stimulation; short-term and long-term efficacy could not be determined because there were too few original RCTs. Moreover, there are no serious adverse effects of this therapy.

Efficacy and safety of eliapixant in diabetic neuropathic pain and prediction of placebo responders with an exploratory novel algorithm: results from the randomized controlled phase 2a PUCCINI study

ABSTRACT

Phase 2a of the PUCCINI study was a placebo-controlled, double-blind, parallel-group, multicenter, proof-of-concept study evaluating the efficacy and safety of the selective P2X3 antagonist eliapixant in patients with diabetic neuropathic pain (DNP) ( ClinicalTrials.gov NCT04641273). Adults with type 1 or type 2 diabetes mellitus with painful distal symmetric sensorimotor neuropathy of >6 months' duration and neuropathic pain were enrolled and randomized 1:1 to 150 mg oral eliapixant twice daily or placebo for 8 weeks. The primary endpoint was change from baseline in weekly mean 24-hour average pain intensity score at week 8. In total, 135 participants completed treatment, 67 in the eliapixant group and 68 in the placebo group. At week 8, the change from baseline in posterior mean 24-hour average pain intensity score (90% credible interval) in the eliapixant group was -1.56 (-1.95, -1.18) compared with -2.17 (-2.54, -1.80) for the placebo group. The mean treatment difference was 0.60 (0.06, 1.14) in favor of placebo. The use of a model-based framework suggests that various factors may contribute to the placebo-responder profile. Adverse events were mostly mild or moderate in severity and occurred in 51% of the eliapixant group and 48% of the placebo group. As the primary endpoint was not met, the PUCCINI study was terminated after completion of phase 2a and did not proceed to phase 2b. In conclusion, selective P2X3 antagonism in patients with DNP did not translate to any relevant improvement in different pain intensity outcomes compared with placebo. Funding: Bayer AG.

Psychedelic Therapy: A Primer for Primary Care Clinicians-Ketamine

BACKGROUND

Ketamine, an arylcyclohexylamine dissociative anesthetic agent, has evolved into a versatile therapeutic. It has a rapid-onset, well-understood cardiovascular effects and a favorable safety profile in clinical use. Its enantiomeric compound, esketamine, was approved by the Food and Drug Administration in 2019 for both treatment-resistant depression and major depressive disorder with suicidal ideation.

AREAS OF UNCERTAINTY

Research indicates dose-dependent impacts on cognition, particularly affecting episodic and working memory following both acute administration and chronic use, albeit temporarily for the former and potentially persistent for the latter. Alongside acute risks to cardiovascular stability, ketamine use poses potential liver toxicity concerns, especially with prolonged or repeated exposure within short time frames. The drug's association with "ketamine cystitis," characterized by bladder inflammation, adds to its profile of physiological risks.

THERAPEUTIC ADVANCES

Data demonstrate a single intravenous infusion of ketamine exhibits antidepressant effects within hours (weighted effect size averages of depression scores (N = 518) following a single 0.5 mg/kg infusion of ketamine is d = 0.96 at 24 hours). Ketamine is also effective at reducing posttraumatic stress disorder (PTSD) symptom severity following repeated infusions (Clinician-Administered PTSD Scale scores: -11.88 points compared with midazolam control). Ketamine also decreased suicidal ideation in emergency settings (Scale for Suicidal Ideation scores: -4.96 compared with midazolam control). Through its opioid-sparing effect, ketamine has revolutionized postoperative pain management by reducing analgesic consumption and enhancing recovery.

LIMITATIONS

Many studies indicate that ketamine's therapeutic effects may subside within weeks. Repeated administrations, given multiple times per week, are often required to sustain decreases in suicidality and depressive symptoms.

CONCLUSIONS

Ketamine's comprehensive clinical profile, combined with its robust effects on depression, suicidal ideation, PTSD, chronic pain, and other psychiatric conditions, positions it as a substantial contender for transformative therapeutic application.

Clinical Phenotypes Supporting the Relationship Between Sleep Disturbance and Impairment of Placebo Effects

Lack of good sleep or insomnia can lead to many health issues, including an elevated risk of cardiovascular disease, obesity, fatigue, low mood, and pain. While chronic pain negatively impacts sleep quality, the relationship between descending pain modulatory systems like placebo effects and sleep quality is not thoroughly known. We addressed this aspect in a cross-sectional study in participants with chronic pain. Placebo effects were elicited in a laboratory setting using thermal heat stimulations delivered with visual cues using classical conditioning and verbal suggestions. We estimated the levels of insomnia severity with the Insomnia Severity Index and the sleep quality with the Pittsburg Sleep Quality Index. The previous night's sleep continuity was assessed as total sleep time, sleep efficiency, and sleep midpoint the night before the experiment. 277 people with chronic pain and 189 pain-free control individuals participated. Participants with chronic pain and insomnia showed smaller placebo effects than those with chronic pain without insomnia. Similarly, poor sleep quality was associated with reduced placebo effects among participants with chronic pain. Clinical anxiety measured by Depression Anxiety Stress Scales partially mediated these effects. In contrast, placebo effects were not influenced by the presence of insomnia or poor sleep quality in pain-free participants. Sleep continuity the night before the experiment did not influence the placebo effects. Our results indicate that participants who experience insomnia and/or poor sleep quality and chronic pain have smaller placebo effects, and that the previous night sleep continuity does not influence the magnitude of placebo effects. PERSPECTIVE: This study examined the relationship between sleep disturbances and experimentally induced placebo effects. We found that individuals with chronic pain who experience insomnia and poor sleep quality demonstrated reduced placebo effects compared to their counterparts with good sleep quality and no insomnia.

Pilot RCT comparing low-dose naltrexone, gabapentin and placebo to reduce pain among people with HIV with alcohol problems

BACKGROUND

To estimate the effects on pain of two medications (low-dose naltrexone and gabapentin) compared to placebo among people with HIV (PWH) with heavy alcohol use and chronic pain.

METHODS

We conducted a pilot, randomized, double-blinded, 3-arm study of PWH with chronic pain and past-year heavy alcohol use in 2021. Participants were recruited in St. Petersburg, Russia, and randomized to receive daily low-dose naltrexone (4.5mg), gabapentin (up to 1800mg), or placebo. The two primary outcomes were change in self-reported pain severity and pain interference measured with the Brief Pain Inventory from baseline to 8 weeks.

RESULTS

Participants (N = 45, 15 in each arm) had the following baseline characteristics: 64% male; age 41 years (SD±7); mean 2 (SD±4) heavy drinking days in the past month and mean pain severity and interference were 3.2 (SD±1) and 3.0 (SD±2), respectively. Pain severity decreased for all three arms. Mean differences in change in pain severity for gabapentin vs. placebo, and naltrexone vs. placebo were -0.27 (95% confidence interval [CI] -1.76, 1.23; p = 0.73) and 0.88 (95% CI -0.7, 2.46; p = 0.55), respectively. Pain interference decreased for all three arms. Mean differences in change in pain interference for gabapentin vs. placebo, and naltrexone vs. placebo was 0.16 (95% CI -1.38, 1.71; p = 0.83) and 0.40 (95% CI -1.18, 1.99; p = 0.83), respectively.

CONCLUSION

Neither gabapentin nor low-dose naltrexone appeared to improve pain more than placebo among PWH with chronic pain and past-year heavy alcohol use.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT4052139).

The Nocebo Effect

Adverse nocebo responses can cause harm to patients and interfere with treatment adherence and effects in both clinic practice and clinical trials. Nocebo responses refer to negative outcomes to active medical treatments in clinical trials or practice that cannot be explained by the treatment's pharmacologic effects. Negative expectancies and nocebo effects are less known than placebo responses. Nocebo effects can be triggered by verbal suggestions, prior negative experiences, observation of others experiencing negative outcomes, and other contextual and environmental factors. As research advances over the years, mechanistic knowledge is accumulating on the neurobiological mechanisms of nocebo effects. This review summarizes studies on different facets of nocebo effects and responses and discusses clinical implications, ethical considerations, and future directions.

Pharmacokinetics and pharmacodynamics of cannabis-based medicine in a patient population included in a randomized, placebo-controlled, clinical trial

Information on the pharmacokinetics (PK) and pharmacodynamics (PD) of orally administered cannabis-based medicine (CBM) in capsule formulation in patient populations is sparse. In this exploratory study, we aimed to evaluate the PK and PD in a probable steady state of CBM in neuropathic pain and spasticity in a population of patients with multiple sclerosis (MS). Of 134 patients participating in a randomized, double-blinded, placebo-controlled, trial, 23 patients with MS (17 female) mean age 52 years (range 21-67) were enrolled in this substudy. They received oral capsules containing Δ9 -tetrahydrocannabinol (THC, n = 4), cannabidiol (CBD, n = 6), a combination (THC&CBD, n = 4), or placebo (n = 9). Maximum doses were 22.5 mg (THC) and 45 mg (CBD) a day divided into three administrations. PD parameters were evaluated for pain and spasticity. Blood samples were analyzed using an ultra-high-performance liquid chromatography-tandem mass spectrometer after protein precipitation and phospholipid removal. PK parameters were estimated using computerized modeling. The variation in daily dose and PK between individuals was considerable in a steady state, yet comparable with previous reports from healthy controls. Based on a simulation of the best model, the estimated PK parameters (mean) for THC (5 mg) were Cmax 1.21 ng/mL, Tmax 2.68 h, and half-life 2.75 h, and for CBD (10 mg) were Cmax 2.67 ng/mL, Tmax 0.10 h, and half-life 4.95 h, respectively. No effect was found on the PD parameters, but the placebo response was considerable. More immediate adverse events were registered in the active treatment groups compared with the placebo group.

Pre-treatment expectations and their influence on subjective symptom change in Crohn's disease

BACKGROUND

Treatment expectations reportedly shape treatment outcomes, but have not been studied in the context of multimodal therapy in Crohn's disease (CD). Therefore, the current study investigated the role of treatment expectations for subjective symptom changes in CD patients who have undergone an integrative multimodal therapy program.

METHODS

Validated questionnaires were completed at the start of the treatment program and post intervention. Pre-treatment expectations and experienced symptom change were assessed with the Generic Rating Scale for Previous Treatment Experiences, Treatment Expectations, and Treatment Effects (GEEE); stress levels were quantified with the Perceived Stress Scale (PSS-10) and disease specific quality of life was quantified with the disease-specific Inflammatory Bowel Disease Questionnaire (IBDQ). We performed multiple linear and Bayesian regression to determine how expectations related to symptom change.

RESULTS

N = 71 CD patients (66.2% female) were included. Stronger expectations regarding symptom improvement (b = 0.422, t = 3.70, p < .001) were associated with higher experienced symptom improvement. Additionally, Bayesian analysis provided strong evidence for including improvement expectations as a predictor of improvement experience (BFinclusion = 13.78).

CONCLUSIONS

In line with research in other disorders, we found that positive treatment expectations were associated with experienced symptom improvement. In contrast, we found no indication that an experience of symptom worsening was associated with positive or negative baseline treatment expectations. Induction of positive expectations might be a potential avenue for improving treatment outcomes in CD therapy.

Effects of MLS Laser on pain, function, and disability in chronic non-specific low back pain: A double-blind placebo randomized-controlled trial

BACKGROUND

Among non-pharmacological interventions, Multiwave Locked System (MLS) Laser therapy has been used in patients with several musculoskeletal pathologies and in combination with other therapeutical interventions. The effects of sole MLS therapy on pain and function in patients with chronic non-specific low-back pain are unknown.

OBJECTIVE

The objective of this study was to investigate the effects of MLS Laser therapy on pain, function, and disability in patients with chronic non-specific low back pain in comparison to a placebo treatment group.

METHODS

Forty-five patients were randomized into two groups: the MLS Laser group and the Sham Laser group, undergoing 8 sessions of either a MLS Laser therapy or a Sham Laser therapy, respectively. At the beginning of the therapy (T0), at the end of the therapy (T1), and 1 month after the end of therapy (T2) patients were assessed for low back pain (by means of a VAS scale), function (by means of kinematic and electromyographic assessment of a forward bending movement) and self-reported disability (by means of the Roland-Morris and Oswestry Disability questionnaires).

RESULTS

There was a significant reduction of pain and disability in both groups at T1 and T2 in comparison with T0. At T2 patients in the MLS group showed a significantly lower pain in comparison with patients in the Sham group (VAS = 2.2 ± 2 vs. 3.6 ± 2.4; p< 0.05). No differences between the two groups were found for function and disability.

CONCLUSION

Both MLS Laser and Sham Laser therapies lead to a significant and comparable reduction in pain and disability in patients with chronic non-specific low back pain. However, one month after treatment, MLS Laser therapy has been found to be significantly more effective in reducing pain as compared to sham treatment.

Interpreting clinical trial outcomes complicated by placebo response with an assessment of false-negative and true-negative clinical trials in depression using propensity-weighting

The objective of this study was to evaluate the performances of the propensity score weighted (PSW) methodology in a post-hoc re-analysis of a failed and a negative RCTs in depressive disorders. The conventional study designs, randomizations, and statistical approaches do not account for the baseline distribution of major non-specific prognostic and confounding factors such as the individual propensity to show a placebo effect (PE). Therefore, the conventional analysis approaches implicitly assume that the baseline PE is the same for all subjects in the trial even if this assumption is not supported by our knowledge on the impact of PE on the estimated treatment effect (TE). The consequence of this assumption is an inflation of false negative results (type II error) in presence of a high proportion of subjects with high PE and an inflation of false positive (type I error) in presence of a high proportion of subjects with low PE value. Differently from conventional approaches, the inverse of the PE probability was used as weight in the mixed-effects analysis to assess TE in the PSW analysis. The results of this analysis indicated an enhanced signal of drug response in a failed trial and confirmed the absence of drug effect in a negative trial. This approach can be considered as a reference prospective or post-hoc analysis approach that minimize the risk of inflating either type I or type II error in contrast to what happens in the analyses of RCT studies conducted with the conventional statistical methodology.

OnabotulinumtoxinA for Pediatric Migraine

BACKGROUND

Migraine is a painful, prevalent, and problematic condition among children. Children need access to safe and effective treatment options to alleviate the impact of this chronic condition on their wellbeing.

CLINICAL IMPLICATIONS

Nurses have a crucial role in supporting patient access to BTX-A. Given the results of this and other studies demonstrating the safety and efficacy of BTX-A in children, nurses can support policy change for health plans to fund this intervention for pediatric migraineurs. Allowing children to receive the safe and effective BTX-A injections will lessen the already significant impact of chronic migraine on their physical, emotional and mental health. Nurses can also play a key role in providing education to patients regarding safe administration of BTX-A for migraine.

AIM

The objective of this study was to define the experiences, effects, and clinical response of children to onabotulinumtoxinA (BTX-A) for migraine prevention.

METHODS

Clinical documentation for patients aged 13-17 years presenting for BTX-A treatment for chronic migraine between 2016-2022 in a community-based specialty clinic within a large, urban, pediatric academic medical center were included. A series of one-way repeated measures (analysis of variance [ANOVA]) were conducted to compare headache frequency, severity, and duration at baseline, and following first and second injections of BTX-A.

RESULTS

Of 32 eligible participants, administration of BTX-A demonstrated a decrease in headache frequency and severity. Participants reported nearly seven fewer headache days per month. Participants reported neck stiffness, fever or flu-like symptoms, fatigue, and worsening pain following BTX-A administration.

CONCLUSIONS

Pediatric migraineurs need therapies that are safe, effective, and accessible. BTX-A was a safe and effective treatment for migraine among the children included in this study.

Efficacy of antiresorptive agents in fibrous dysplasia and McCune Albright syndrome, a systematic review and meta-analysis

Fibrous dysplasia (FD) is a rare skeletal disorder in which normal bone is replaced by a fibro-osseous tissue, resulting in possible deformities and fractures. The aim of this systematic review and meta-analysis was to synthesize the available evidence on the use of antiresorptive drugs in FD in terms of changes in bone turnover markers (BTMs), bone mineral density (BMD), and reducing pain. Three databases were searched in October 2022, with an update in July 2023. Of the 1037 studies identified, 21 were retained after eligibility assessment. A random-effects model was used to calculate global effect size and the corresponding standard error. Pamidronate and Denosumab were the most reported drugs in a total of 374 patients assessed. The initiation of treatments was accompanied by an average reduction of 40.5% [CI95% -51.6, -29.3] in the bone resorption parameters, and 22.0% [CI95% -31.9, -12.1] in the parameters of bone formation after 6-12 months. BMD was increased in both FD lesions and in the unaffected skeleton. Pain was reduced by 32.7% [CI95% -52.7, -12.6] after 6-12 months of treatment, and by 44.5% [CI95% -65.3, -23.6] after a mean 41.2 months of follow-up. The variation in pain was highly correlated to variation in bone resorption (R2 = 0.08, p < 0.0001) and formation parameters (R2 = 0.17, p < 0.0001). This study supports the overall efficacy of antiresorptive therapies in terms of reducing bone remodeling, improving bone density, and pain in FD.

Placebo effects on all-cause mortality of patients with COVID-19 in randomized controlled trials of interleukin 6 antagonists: A systematic review and network meta-analysis

AIM

Many randomized controlled trials (RCTs) have investigated the use of interleukin 6 antagonists for the treatment of coronavirus disease 2019 (COVID-19), yielding inconsistent results. This network meta-analysis (NMA) aimed to identify the source of these inconsistent results by reassessing whether participants treated with standard of care (SoC) plus placebo have different all-cause mortality from those treated with SoC alone and to reevaluate the efficacy of interleukin 6 antagonists in the treatment of COVID-19.

METHODS

We conducted a systematic search for relevant RCTs from the inception of electronic databases through 1 September 2022. The primary outcome was all-cause mortality. The secondary outcomes were the incidences of major medical events, secondary infections, all-cause discontinuation, and serious adverse events.

RESULTS

The results of NMA of 33 RCTs showed that patients with COVID-19 treated with SoC plus placebo had lower odds of all-cause mortality than those who received SoC alone (OR, 0.75 [95% confidence interval, 0.58-0.97]). This finding remained consistent after excluding studies with no incident deaths. In addition, when we consider the impact of the widely promoted COVID-19 vaccination and newly developed antiviral treatment strategy, the results from the analysis of the RCT published in 2021 and 2022 remained similar.

CONCLUSION

These findings suggest the potential influence of placebo effects on the treatment outcomes of COVID-19 in RCTs. When evaluating the efficacy of treatment strategies for COVID-19, it is crucial to consider the use of placebo in the design of clinical trials.

Placebo response in sham-acupuncture-controlled trials for migraine: A systematic review and meta-analysis

AIM

To understand the placebo response of acupuncture and its effect on migraine and optimize the design of future acupuncture clinical trials on migraine treatment.

METHODS

Randomized controlled trials with sham acupuncture as a control in migraine treatment were searched in four English databases from inception to September 1, 2022. The primary outcome was placebo response rate. Secondary outcomes were migraine symptoms, emotional condition, and quality of life. Factors associated with placebo response were also explored. Results were combined using risk difference (RD) or standardized mean difference (SMD) and 95% confidence interval (CI) with a random effects model.

RESULTS

The final analysis included 21 studies involving 1177 patients. The pooled response rate of sham acupuncture was 0.34 (RD, 95% CI 0.23-0.45, I2 89.8%). The results (SMD [95% CI]) showed significant improvements in migraine symptoms (pain intensity -0.56 [-0.73 to -0.38], and episode conditions -0.55 [-0.75 to -0.35]); emotional condition (anxiety scale -0.49 [-0.90 to -0.08] and depression scale -0.21 [-0.40 to -0.03]); and quality of life on the Migraine-Specific Quality-of-Life Questionnaire (restrictive 0.78 [0.61-0.95]; preventive 0.52 [0.35-0.68]; and emotional 0.45 [0.28-0.62]) and on the Medical Outcomes Study Short-Form (physical 0.48 [0.34-0.62] and mental 0.21 [0.02-0.41]). Only acupuncture treatment frequency had a significant impact on the placebo response rate (RD 0.49 vs. 0.14; p = 0.00).

CONCLUSIONS

The effect sizes for placebo response of sham acupuncture varied across migraine treatment trials. Further studies should routinely consider adjusting for a more complete set of treatment factors.

The influence of psychological traits and prior experience on treatment expectations

BACKGROUND

Placebo and nocebo responses are modulated by the treatment expectations of participants and patients. However, interindividual differences predicting treatment expectations and placebo responses are unclear. In this large-scale pooled analysis, we aim to investigate the influence of psychological traits and prior experiences on treatment expectations.

METHODS

This paper analyses data from six different placebo studies (total n = 748). In all studies, participants' sociodemographic information, treatment expectations and prior treatment experiences and traits relating to stress, somatization, depression and anxiety, the Big Five and behavioral inhibition and approach tendencies were assessed using the same established questionnaires. Correlation coefficients and structural equation models were calculated to investigate the relationship between trait variables and expectations.

RESULTS

We found small positive correlations between side effect expectations and improvement expectations (r = 0.187), perceived stress (r = 0.154), somatization (r = 0.115), agitation (r = 0.108), anhedonia (r = 0.118), and dysthymia (r = 0.118). In the structural equation model previous experiences emerged as the strongest predictors of improvement (β = 0.32, p = .005), worsening (β = -0.24, p = .005) and side effect expectations (β = 0.47, p = .005). Traits related to positive affect (β = - 0.09; p = .007) and negative affect (β = 0.04; p = .014) were associated with side effect expectations.

DISCUSSION

This study is the first large analysis to investigate the relationship between traits, prior experiences and treatment expectations. Exploratory analyses indicate that experiences of symptom improvement are associated with improvement and worsening expectations, while previous negative experiences are only related to side effect expectations. Additionally, a proneness to experience negative affect may be a predictor for side effect expectation and thus mediate the occurrence of nocebo responses.

Neurostimulation for Chronic Pain: A Systematic Review of High-Quality Randomized Controlled Trials With Long-Term Follow-Up

OBJECTIVE

This study aimed to review the best evidence on the long-term efficacy of neurostimulation for chronic pain.

MATERIALS AND METHODS

We systematically reviewed PubMed, CENTRAL, and WikiStim for studies published between the inception of the data bases and July 21, 2022. Randomized controlled trials (RCTs) with a minimum of one-year follow-up that were of high methodologic quality as ascertained using the Delphi list criteria were included in the evidence synthesis. The primary outcome was long-term reduction in pain intensity, and the secondary outcomes were all other reported outcomes. Level of recommendation was graded from I to III, with level I being the highest level of recommendation.

RESULTS

Of the 7119 records screened, 24 RCTs were included in the evidence synthesis. Therapies with recommendations for their usage include pulsed radiofrequency (PRF) for postherpetic neuralgia, transcutaneous electrical nerve stimulation for trigeminal neuralgia, motor cortex stimulation for neuropathic pain and poststroke pain, deep brain stimulation for cluster headache, sphenopalatine ganglion stimulation for cluster headache, occipital nerve stimulation for migraine, peripheral nerve field stimulation for back pain, and spinal cord stimulation (SCS) for back and leg pain, nonsurgical back pain, persistent spinal pain syndrome, and painful diabetic neuropathy. Closed-loop SCS is recommended over open-loop SCS for back and leg pain. SCS is recommended over PRF for postherpetic neuralgia. Dorsal root ganglion stimulation is recommended over SCS for complex regional pain syndrome.

CONCLUSIONS

Neurostimulation is generally effective in the long term as an adjunctive treatment for chronic pain. Future studies should evaluate whether the multidisciplinary management of the physical perception of pain, affect, and social stressors is superior to their management alone.