Placebo effects of a sham opioid solution: a randomized controlled study in patients with chronic low back pain

Do patients with fibromyalgia syndrome and healthy people differ in their opinions on placebo effects in routine medical care?

OBJECTIVES

Placebo effects can relieve acute and chronic pain in both research and clinical treatments by learning mechanisms. However, the application of placebo-based treatment strategies in routine medical care is questioned. The current study investigated the opinions of patients with fibromyalgia and healthy controls regarding learning of placebo effects and their practical applications.

METHOD

An online survey asked 158 age- and sex-matched adult patients and controls (79 per group) to rate the perceived influence of various placebo learning mechanisms on pain relief, and the acceptability and perceived effectiveness of placebo-based strategies (open-label, closed-label, dose-extending, and treatment-enhancing strategies). Respondents' knowledge about placebo effects was obtained through a 7-item quiz.

RESULTS

The groups did not differ in the perceived influence of placebo learning mechanisms on pain relief (p = 0.217). Controls considered closed-label and treatment-enhancing strategies more acceptable than patients (p = 0.003 and p < 0.001), whereas controls perceived all strategies more effective. In both groups, closed-label strategies were significantly less acceptable than any other strategy (p-values < 0.001), and treatment-enhancing or dose-extending strategies were most acceptable. Higher acceptability was predicted by higher perceived effectiveness ratings (p < 0.001). Also, increased placebo knowledge was related to higher acceptability (p = 0.03) and perceived effectiveness (p < 0.001).

DISCUSSION

This survey suggests that both the medical history of patients and knowledge about placebo effects affect the acceptability and perceived effectiveness of placebo-based strategies. Furthermore, strategies that are transparent, assumed effective, or combined with existing medical treatments are deemed most acceptable. Keeping these factors in mind is essential for the clinical implementation of placebo-based strategies in routine medical care.

A randomized trial investigating the impact of response expectancy on the counting blessings intervention: the role of optimism as a moderator

Introduction

This randomized controlled trial aimed to address a knowledge gap concerning the mechanisms responsible for the efficacy of gratitude interventions. Specifically, we investigated how various response expectancies (positive, ambiguous + negative, and no expectancy) impact the efficacy of the "counting blessings" intervention in influencing positive and negative emotions. Additionally, the study explores how optimism levels (high, medium, low) interact with these expectancies to influence intervention efficacy.

Method

A total of 529 adult volunteers were recruited through social media and randomly assigned to one of three experimental conditions, Positive Condition (PC), Ambiguous + Negative Condition (ANC), No Expectancy Condition (NEC), using a Random Sequence Generator. Of these, 142 participants completed the seven-day counting blessings intervention, and 111 participated in a follow-up assessment 1 month later. Missing data were addressed using multiple imputation. The main outcomes were changes in positive and negative emotions, with moderation analysis assessing the interaction between optimism levels and response expectancies. The study adhered to the CONSORT guidelines.

Results

While no significant interaction was found between experimental conditions and time regarding emotional outcomes (p ˃ 0.05), moderation analysis revealed differential interactions between optimism levels and expectancies, particularly influencing positive emotions (p < 0.009). For participants with low optimism, positive emotions significantly increased from post-intervention to follow-up in the PC (t = -2.42, p < 0.016) and from pre-intervention to post-intervention in the ANC (t = 2.41, p < 0.018). Participants with medium optimism experienced an increase in positive emotions across all conditions from pre-intervention to follow-up and from post-intervention to follow-up (ps  < 0.05). High optimism participants showed an increase in positive emotions from pre-intervention to follow-up and post-intervention to follow-up in the PC (t = 2.09, p < 0.038 and t = 3.06, p < 0.003) and NEC c (t = -2.76, p < 0.006 and t = 2.74, p < 0.007).

Conclusion

Our findings emphasize the effectiveness of a brief gratitude journal and underscore the nuanced role of response expectancy, especially in interaction with the initial level of optimism, in enhancing positive emotions. These results hold significance for both theoretical understanding and clinical applications.

Treatment Expectations-You Get What You Expect-and Depression Plays a Role

Positive treatment expectations demonstrably shape treatment outcomes regarding pain and disability in patients with chronic low back pain. However, knowledge about positive and negative treatment expectations as putative predictors of interindividual variability in treatment outcomes is sparse, and the role of other psychological variables of interest, especially of depression as a known predictor of long-term disability, is lacking. We present results of the first prospective study considering expectations in concert with depression in a sample of 200 patients with chronic low back pain undergoing an inpatient interdisciplinary multimodal pain therapy. We analyzed the characteristics of pain and disability, treatment expectation, and depression assessed at the beginning (T0), at the end of (T1), and at 3-month follow-up (T2) of interdisciplinary multimodal pain therapy. Treatment expectations did emerge as a significant predictor of changes in pain intensity and disability, respectively, showing that positive expectations were associated with better treatment outcomes. Mediation analyses revealed a partially mediating effect of treatment expectations on the relation between depression and pain outcomes. PERSPECTIVE: These results expand knowledge regarding the role of treatment expectations in individual treatment outcome trajectories in chronic pain patients, paving the way for much-needed efforts toward optimizing patient expectations and personalized approaches in clinical settings.

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.

Placebo Effects on the Enjoyment of Physical Activity and Performance among Kindergarten Children: A Randomized Controlled Trial

Studies with adults and school children have shown that placebos can enhance motivation and performance in physical activities. This study aimed to investigate whether similar effects are present in kindergarten-aged children. A total of 101 children (58 girls, 43 boys) aged 3 to 6 years were randomly assigned to one of two groups that either received a deceptive placebo (DP: "magic potion") or a nondeceptive placebo (NDP: "water") to enhance physical abilities. Each child completed three tasks (sprinting; balancing: standing on a balance board; strength: using a handheld dynamometer) both with and without the placebo. The variables assessed included task performance, enjoyment, and expected and perceived placebo efficacy (measured with nonverbal pictorial rating scales). Results showed that both the DP and NDP increased speed. For strength, balance, and task enjoyment (which was very high), no placebo-induced changes were observed. Expected efficacy was higher for the DP; perceived efficacy did not differ between DP and NDP. In conclusion, reported outcome expectations indicated that kindergarten-aged children were already able to differentiate between the two types of placebos which exhibited positive effects concerning running performance. This encourages further research on using nondeceptive placebos to enhance physical activity, which is crucial for children's overall health.

Preoperative Anxiolysis and Treatment Expectation (PATE Trial): open-label placebo treatment to reduce preoperative anxiety in female patients undergoing gynecological laparoscopic surgery - study protocol for a bicentric, prospective, randomized-controlled trial

One of the most common concerns of patients undergoing surgery is preoperative anxiety, with a prevalence of up to 48%. The effects of preoperative anxiety continue beyond the preoperative period and are associated with more severe postoperative pain and poorer treatment outcomes. Treatment options for preoperative anxiety are often limited as sedatives cause side effects and their efficacy remains controversial. Placebo research has shown that optimization of positive treatment expectations, as can be achieved through placebo administration and education, has clinically relevant effects on preoperative anxiety, pain and treatment outcomes. As the administration of masked placebos raises ethical questions, clinical studies have increasingly focused on the use of open, non-deceptive placebo administration (open-label placebo, OLP). The use of OLPs to reduce preoperative anxiety and modify clinically relevant postoperative outcomes has not yet been investigated. This bicentric, prospective, randomized-controlled clinical trial (PATE Trial; German Registry for Clinical Studies DRKS00033221), an associated project of the Collaborative Research Center (CRC) 289 "Treatment Expectation", aims to alleviate preoperative anxiety by optimizing positive treatment expectations facilitated by OLP. Furthermore, this study examines a potential enhancement of these effects through aspects of observational learning, operationalized by a positive expectation-enhancing video. In addition, patient's perspective on the self-efficacy and appropriateness of OLPs prior to surgery will be assessed. To achieve these objectives, female patients will be randomized into three groups before undergoing gynecological laparoscopic surgery. One group receives the OLP with a positive rationale conveyed by a study physician. A second group receives the same intervention, OLP administration and rationale provided by a physician, and additionally watches a video on OLP presenting a satisfied patient. A third group receives standard treatment as usual (TAU). Outcome measures will be effects on preoperative anxiety and postoperative experience, particularly visceral and somatic postoperative pain. As the non-deceptive administration of placebos; when indicated; may yield positive outcomes without side effects, and as current treatment of preoperative anxiety is limited, evidence from clinical placebo research has the potential to improve outcomes and patient experience in the surgical setting.

Predictors of success of pharmacological management in patients with chronic lower back pain: systematic review

BACKGROUND

Conservative management is recommended as the first therapeutic step in chronic low back pain (LBP), but there is no available evidence regarding the possible effect of patients' baseline characteristics on the therapeutic outcomes. A systematic review of the literature was performed to investigate this point.

METHODS

In February 2024, all the level I studies investigating the role of pharmacological management for chronic LBP were accessed. Data concerning the patient demographic at baseline were collected: number of patients and related mean BMI and age, duration of the symptoms, duration of the follow-up, percentage of females, Numeric Rating Scale (NRS), the Roland Morris Disability Questionnaire (RMQ), Oswestry Disability Index (ODI). The outcomes at the last follow-up were evaluated through NRS, RMQ, and ODI. A multiple linear model regression diagnostic through the Pearson Product-Moment Correlation Coefficient (r) was used.

RESULTS

Data from 47 articles (9007 patients) were obtained. The analysis yielded the following significant associations: age at baseline and NRS at follow-up (r = - 0.22; P = 0.04), NRS at baseline with NRS (r = 0.26; P = 0.03) and RMQ (r = - 0.58; P = 0.02) at follow-up, RMQ at baseline and the same at follow-up (r = 0.69; P = 0.0001).

CONCLUSION

Older age, higher BMI, presence of comorbidities, higher ODI and a long history of symptoms or surgical treatments do not reduce the efficacy of pharmacological management of chronic LBP. However, pharmacological therapy is not an effective option for patients with high baseline RMQ.

LEVEL OF EVIDENCE

I systematic review of RCTs.

The Roles of Endogenous Opioids in Placebo and Nocebo Effects: From Pain to Performance to Prozac

Placebo and nocebo effects have been well documented for nearly two centuries. However, research has only relatively recently begun to explicate the neurobiological underpinnings of these phenomena. Similarly, research on the broader social implications of placebo/nocebo effects, especially within healthcare delivery settings, is in a nascent stage. Biological and psychosocial outcomes of placebo/nocebo effects are of equal relevance. A common pathway for such outcomes is the endogenous opioid system. This chapter describes the history of placebo/nocebo in medicine; delineates the current state of the literature related to placebo/nocebo in relation to pain modulation; summarizes research findings related to human performance in sports and exercise; discusses the implications of placebo/nocebo effects among diverse patient populations; and describes placebo/nocebo influences in research related to psychopharmacology, including the relevance of endogenous opioids to new lines of research on antidepressant pharmacotherapies.

Can open label placebos improve pain and gluten tolerance via open label placebos in fibromyalgia patients? A study protocol for a randomised clinical trial in an outpatient centre

INTRODUCTION

Fibromyalgia syndrome (FMS) is defined as a medical condition with chronic widespread musculoskeletal pain accompanied by mood disorders, fatigue and sleep disturbances. Treatment of this condition can often be challenging. As nutrition in general and nutritional interventions in the context of illness management become more and more important, current research also focuses on the relevance of diets for FMS, including gluten as field of interest. To date, there is no clear evidence that a gluten-free diet or other nutritional interventions are significantly important for the reduction of pain in the context of FMS. Only a very few studies show that FMS patients respond to a gluten-free diet and that cytokine production (also in FMS) can be reduced through the change. However, these studies have not investigated whether and to what extent cognitive factors, such as the expectation of symptom reduction triggered by diet, play a role. Recent research shows that treatment expectation plays an important role in the course of the disease and in the effectiveness of treatment approaches. For example, there are promising pain treatment options using open-label placebos (OLPs), which show that expectation alone, rather than the pharmacological substance of medication, can reduce pain experience. In our study protocol, we hypothesise that treatment expectation can be positively influenced by the given information regarding the placebos, resulting in improved treatment outcomes for pain and indigestions.

METHODS AND ANALYSIS

In this trial, patients with FMS will undergo a food challenge and take an OLP (patients will be informed about the placebo), followed by a 3-week OLP treatment. The subjects will be randomised into four groups: (a) gluten-free porridge+neutral OLP instructions; (b) gluten-free porridge+positive OLP instructions; (c) gluten-containing porridge+neutral OLP instructions and (d) gluten-containing porridge+positive OLP instructions. Patients will be recruited via different institutions and support groups in Hamburg. The inclusion criteria are (a) diagnosed FMS, (b) absence of wheat allergy, coeliac disease or pain-related red flags and (c) being a minimum age of 18 years. The study requires 100 subjects to assess the primary outcomes: pain intensity and occurence of indigestion. Secondary outcomes are functional capacity, treatment expectation, and different pain-related and inflammation-related blood parameters. The measure time points will be before and after the food challenge and before and after the 3-week OLP treatment.

ETHICS AND DISSEMINATION

Ethical approval was obtained in October 2021 from the Hamburg Medical Ethics Council. The results of the study will be disseminated through publications, presentations and conference meetings.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (DRKS; DRKS00027130).

Effects of an open-label placebo intervention on reactions to social exclusion in healthy adults: a randomized controlled trial

Social exclusion, that is being left out by others, can have adverse consequences for individuals' psychological well-being. Even short-term experiences of social exclusion strongly threaten basic psychological needs and cause so-called social pain. Prior research suggests an overlap between the experience of social and physical pain that, amongst others, is reflected by the effectiveness of physical pain treatments in alleviating social pain. Drawing upon these prior findings, we here explore whether open-label placebos, which have previously been found to be effective in reducing physical pain, can alleviate social pain following social exclusion. Seventy-four healthy participants were randomly assigned to one of four conditions in a 2 × 2 between-subjects design: First, they either received an open-label placebo intervention or no treatment. Second, they either experienced inclusion or exclusion by their co-players in the interactive ball-tossing game Cyberball. We find that excluded participants in the open-label placebo condition experienced significantly less hurt feelings compared to those in the control condition (Cohen's d = 0.77). There was no effect of treatment for need threat. The findings suggest new possibilities to alleviate social pain, which is of particular interest in the context of preventing destructive and maladaptive behaviors in situations where functional coping strategies are unavailable.

A qualitative study of imaginary pills and open-label placebos in test anxiety

BACKGROUND

The efficacy of open-label placebos (OLPs) has been increasingly demonstrated and their use holds promise for applications compatible with basic ethical principles. Taking this concept one step further an imaginary pill (IP) intervention without the use of a physical pill was developed and tested in a randomized controlled trial (RCT). To explore participants' experiences and views, we conducted the first qualitative study in the field of IPs.

METHODS

A reflexive thematic analysis (RTA) of semi-structured interviews with test anxious students (N = 20) was nested in an RCT investigating an IP and OLP intervention. In addition, open-ended questions from the RCT were evaluated (N = 114) to corroborate the RTA and pill characteristics were included to more accurately capture the IP experience.

RESULTS

Four key themes were identified: (1) attitude towards the intervention, (2) applicability of the intervention, (3) experience of effects, and (4) characteristics of the imagination. The IP intervention was well-accepted, easily applicable, and various effects, pill characteristics and appearances were described. While many participants did not desire a physical pill, either due to the absence of the imagination component or aversion to pills, the approach was considered to be cognitively and time demanding, which in turn, however, encouraged the establishment of a therapeutic ritual that protected against the increase in test anxiety during the preparation phase. OLP findings were comparable, and especially the importance of a treatment rationale was stressed in both groups, counteracting an initial ambivalent attitude. The RTA findings were supported by the open-ended questions of the RCT.

CONCLUSION

IPs appear to be a well-accepted and easily applicable intervention producing a variety of beneficial effects. Thus, the IP approach might serve as an imaginary based alternative to OLPs warranting further investigations on its application to harness placebo effects without a physical pill.

The roles of expectation, comparator, administration route, and population in open-label placebo effects: a network meta-analysis

Three meta-analyses have demonstrated the clinical potential of open-label placebos (OLPs). However, there is a need to synthesize the existing evidence through more complex analyses that would make it possible to answer questions beyond mere efficacy. Such analyses would serve to improve the understanding of why and under what circumstances OLPs work (e.g., depending on induced expectations or across different control groups). To answer these questions, we conducted the first network meta-analyses in the field of OLPs. Our analyses revealed that OLPs could be beneficial in comparison to no treatment in nonclinical (12 trials; 1015 participants) and clinical populations (25 trials; 2006 participants). Positive treatment expectations were found to be important for OLPs to work. Also, OLP effects can vary depending on the comparator used. While the kind of administration route had no substantial impact on the OLP effects, effects were found to be larger in clinical populations than in nonclinical populations. These results suggest that the expectation, comparator, administration route, and population should be considered when designing and interpreting OLP studies.

The Biology of Placebo and Nocebo Effects on Experimental and Chronic Pain: State of the Art

(1) Background: In recent years, placebo and nocebo effects have been extensively documented in different medical conditions, including pain. The scientific literature has provided strong evidence of how the psychosocial context accompanying the treatment administration can influence the therapeutic outcome positively (placebo effects) or negatively (nocebo effects). (2) Methods: This state-of-the-art paper aims to provide an updated overview of placebo and nocebo effects on pain. (3) Results: The most common study designs, the psychological mechanisms, and neurobiological/genetic determinants of these phenomena are discussed, focusing on the differences between positive and negative context effects on pain in experimental settings on healthy volunteers and in clinical settings on chronic pain patients. Finally, the last section describes the implications for clinical and research practice to maximize the medical and scientific routine and correctly interpret the results of research studies on placebo and nocebo effects. (4) Conclusions: While studies on healthy participants seem consistent and provide a clear picture of how the brain reacts to the context, there are no unique results of the occurrence and magnitude of placebo and nocebo effects in chronic pain patients, mainly due to the heterogeneity of pain. This opens up the need for future studies on the topic.

Between guidelines and clinical trials: evidence-based advice on the pharmacological management of non-specific chronic low back pain

The pharmacological management of nonspecific chronic low back pain (NCLBP) aims to restore patients' daily activities and improve their quality of life. The management of NCLBP is not well codified and extremely heterogeneous, and residual symptoms are common. Pharmacological management should be considered as co-adjuvant to non-pharmacological therapy, and should be guided by the symptoms reported by the patients. Depending on the individual severity of NCLPB, pharmacological management may range from nonopioid to opioid analgesics. It is important to identify patients with generalized sensory hypersensitivity, who may benefit from dedicated therapy. This article provides an evidence-based overview of the principles of pharmacological management of NCLPB.

Impact of contextual factors on patient outcomes following conservative low back pain treatment: systematic review

BACKGROUND AND OBJECTIVE

Chronic low back pain is pervasive, societally impactful, and current treatments only provide moderate relief. Exploring whether therapeutic elements, either unrecognised or perceived as implicit within clinical encounters, are acknowledged and deliberately targeted may improve treatment efficacy. Contextual factors (specifically, patient's and practitioner's beliefs/characteristics; patient-practitioner relationships; the therapeutic setting/environment; and treatment characteristics) could be important, but there is limited evidence regarding their influence. This research aims to review the impact of interventions modifying contextual factors during conservative care on patient's pain and physical functioning.

DATABASES AND DATA TREATMENT

Four electronic databases (Medline, CINAHL, PsycINFO and AMED) were searched from 2009 until 15th February 2022, using tailored search strategies, and resulted in 3476 unique citations. After initial screening, 170 full-text records were potentially eligible and assessed against the inclusion-exclusion criteria. Thereafter, studies were assessed for methodological quality using a modified Downs and Black scale, data extracted, and synthesised using a narrative approach.

RESULTS

Twenty-one primary studies (N = 3075 participants), were included in this review. Eight studies reported significant improvements in pain intensity, and seven in physical functioning, in favour of the contextual factor intervention(s). Notable contextual factors included: addressing maladaptive illness beliefs; verbal suggestions to influence symptom change expectations; visual or physical cues to suggest pain-relieving treatment properties; and positive communication such as empathy to enhance the therapeutic alliance.

CONCLUSION

This review identified influential contextual factors which may augment conservative chronic low back pain care. The heterogeneity of interventions suggests modifying more than one contextual factor may be more impactful on patients' clinical outcomes, although these findings require judicious interpretation.

Analgetische Placeboeffekte und Implikationen für die Behandlung chronischer Schmerzen

Die Behandlung von chronischen Schmerzen kann langwierig sein. Erste Ansätze zur Nutzung von Placeboeffekten bei der Behandlung von chronischen Schmerzen zeigen erfolgversprechende Ergebnisse und können dazu beitragen, die z. T. frustranen Therapieoptionen zu verbessern. Daher sollten Placeboeffekte zur verbesserten Behandlung genutzt werden. Im derzeitigen Modell zur Entstehung von Placeboeffekten spielt die Erwartung eine zentrale Rolle. Eine positive oder negative Erwartung wird durch psychologische und biologische „State“- und „Trait“-Faktoren der Patient:innen sowie die früheren Lernerfahrungen, die der:die Patient:in mitbringt, beeinflusst. Aus diesem Modell ergeben sich Implikationen für die klinische Praxis: Positive Erwartungen sollten unterstützt werden, wobei unrealistische Erwartungen wiederum den Placeboeffekt reduzieren. Negative Erwartungen sollten kritisch diskutiert werden. Es sollte im interdisziplinären Team eine gemeinsame Botschaft an die Patient:innen vermittelt werden. Open-Label-Placebos können als Intervention genutzt werden, um die Selbstwirksamkeit zu steigern.

Placebo induced expectations of mood enhancement generate a positivity effect in emotional processing

A perceptual bias towards negative emotions is a consistent finding in mood disorders and a major target of therapeutic interventions. Placebo responses in antidepressant treatment are substantial, but it is unclear whether and how underlying expectancy effects can modulate response biases to emotional inputs. In a first attempt to approach this question, we investigated how placebo induced expectation can shape the perception of specific emotional stimuli in healthy individuals. In a controlled cross-over design, positive treatment expectations were induced by verbal instructions and a hidden training manipulation combined with an alleged oxytocin nasal spray before participants performed an emotion classification task on happy and fearful facial expressions with varying intensity. Analyses of response criterion and discrimination ability as derived from emotion-specific psychometric functions demonstrate that expectation specifically lowered participants’ threshold for identifying happy emotions in general, while they became less sensitive to subtle differences in emotional expressions. These indications of a positivity bias were directly correlated with participants’ treatment expectations as well as subjective experiences of treatment effects and went along with a significant mood enhancement. Our findings show that expectations can induce a perceptual positivity effect in healthy individuals which is probably modulated by top-down emotion regulation and which may be able to improve mood state. Clinical implications of these promising results now need to be explored in studies of expectation manipulation in patients with mood disorders.

[Psychosocial factors in pain and pain management : A statement]

Although psychosocial factors have a profound impact on the experience of pain and pain recovery, the transfer to clinical application has so far been insufficient. With this article, a task force of the special interest group "Psychosocial Aspects of Pain" of the German Pain Society (Deutsche Schmerzgesellschaft e. V.) would like to draw attention to the considerable discrepancy between existing scientific evidence on the importance of psychosocial factors in the development of chronic pain disorders and the translation of these findings into the care of pain patients. Our objective is a stronger integration of psychological and psychosomatic expertise in pain treatment and research, as well as the improvement of structural and institutional conditions, to achieve an increased consideration of psychosocial aspects. In this way, modern, integrative and complex pain concepts can reach the patient. Based on these fundamental findings on the importance of psychosocial factors in pain and pain treatment, implications for the transfer to clinic and further research will be shown.

Optimising treatment expectations in chronic lower back pain through observing others: a study protocol for a randomised clinical trial

INTRODUCTION

Chronic lower back pain (CLBP) is a frequent cause of medical consultations worldwide, and it results in decreased quality of life and disability. Current treatments for CLBP are often not effective, and alternatives are urgently needed. Three promising possibilities have emerged: (1) open-label placebo treatment reduces chronic pain, (2) placebo treatment is as efficacious as opioid treatment with a high correlation between patient expectation and treatment outcome, and (3) observing positive effects in another patient can improve functional capacity. We hypothesise that treatment expectations can be positively influenced through social observation and improve treatment outcome.

METHODS AND ANALYSIS

In our clinical trial, we will randomise patients with CLBP into five groups. Two groups receive either a 3 week course of treatment with an analgesic (ANA) (metamizole/dipyrone) or with open-label placebos (OLP). For one of each group, we will build treatment expectations through observational learning and assess its impact on the treatment. For this purpose, one group each will watch either a positive or a neutral video. The intervention groups will be compared with a control group that will not be given any medication or observational learning. Participants will be recruited via all institutions in the Hamburg metropolitan area that treat patients with CLBP. Patients are eligible for inclusion if they are at least 18 years or older, have CLBP (of at least 3 months duration), and agree to potentially receive an active ANA or an OLP. Patients with pain-related "red flags" will be excluded. The study requires 150 participants (30 participants per group) to assess the differences in the primary outcome, pain intensity. Secondary outcomes include changes in treatment expectations, anxiety, comorbid depression, stress-related neuroendocrine measures, functional and structural connectivity, functional capacity, and ANA consumption. All outcomes and treatment expectations will be measured before and after the intervention and 3 months post-intervention.

ETHICS AND DISSEMINATION

Ethical approval was obtained in January 2020 from the Hamburg Medical Ethics Council (ref number PV7067). Outcomes will be disseminated through publications in peer-reviewed journals and presentations at national and international conference meetings.

TRIAL REGISTRATION NUMBER

The approved trial protocol was registered at the German Clinical Trials Register (DRKS) and can be found at drks.de (Identifier: DRKS00024418).

Conditioning to Enhance the Effects of Repetitive Transcranial Magnetic Stimulation on Experimental Pain in Healthy Volunteers

OBJECTIVE

In this proof-of-concept study we sought to explore whether the combination of conditioning procedure based on a surreptitious reduction of a noxious stimulus (SRPS) could enhance rTMS hypoalgesic effects [i.e., increase heat pain threshold (HPT)] and augment intervention expectations in a healthy population.

METHODS

Forty-two healthy volunteers (19-35 years old) were enrolled in a randomized crossover-controlled study and were assigned to one of two groups: (1) SRPS and (2) No SRPS. Each participant received two consecutive sessions of active or sham rTMS over the M1 area of the right hand on two visits (1) active, (2) sham rTMS separated by at least one-week interval. HPT and the temperature needed to elicit moderate heat pain were measured before and after each rTMS intervention on the right forearm. In the SRPS group, conditioning consisted of deliberately decreasing thermode temperature by 3°C following intervention before reassessing HPT, while thermode temperature was held constant in the No SRPS group. Intervention expectations were measured before each rTMS session.

RESULTS

SRPS conditioning procedure did not enhance hypoalgesic effects of rTMS intervention, neither did it modify intervention expectations. Baseline increases in HPT were found on the subsequent intervention session, suggesting variability of this measure over time, habituation or a possible "novelty effect."

CONCLUSION

Using a SRPS procedure in healthy volunteers did not enhance rTMS modulating effects on experimental pain sensation (i.e., HPT). Future studies are therefore needed to come up with a conditioning procedure which allows significant enhancement of rTMS pain modulating effects in healthy volunteers.

What Should Clinicians Tell Patients about Placebo and Nocebo Effects? Practical Considerations Based on Expert Consensus

INTRODUCTION

Clinical and laboratory studies demonstrate that placebo and nocebo effects influence various symptoms and conditions after the administration of both inert and active treatments.

OBJECTIVE

There is an increasing need for up-to-date recommendations on how to inform patients about placebo and nocebo effects in clinical practice and train clinicians how to disclose this information.

METHODS

Based on previous clinical recommendations concerning placebo and nocebo effects, a 3-step, invitation-only Delphi study was conducted among an interdisciplinary group of internationally recognized experts. The study consisted of open- and closed-ended survey questions followed by a final expert meeting. The surveys were subdivided into 3 parts: (1) informing patients about placebo effects, (2) informing patients about nocebo effects, and (3) training clinicians how to communicate this information to the patients.

RESULTS

There was consensus that communicating general information about placebo and nocebo effects to patients (e.g., explaining their role in treatment) could be beneficial, but that such information needs to be adjusted to match the specific clinical context (e.g., condition and treatment). Experts also agreed that training clinicians to communicate about placebo and nocebo effects should be a regular and integrated part of medical education that makes use of multiple formats, including face-to-face and online modalities.

CONCLUSIONS

The current 3-step Delphi study provides consensus-based recommendations and practical considerations for disclosures about placebo and nocebo effects in clinical practice. Future research is needed on how to optimally tailor information to specific clinical conditions and patients' needs, and on developing standardized disclosure training modules for clinicians.

Placebo effects in low back pain: A systematic review and meta-analysis of the literature

BACKGROUND AND OBJECTIVE

The current treatments of primary musculoskeletal low back pain (LBP) have a low to moderate efficacy, which might be improved by looking at the contribution of placebo effects. However, the size of true placebo effects in LBP is unknown. Therefore, a systematic review and meta-analysis were executed of randomized controlled trials investigating placebo effects in LBP.

DATABASES AND DATA TREATMENT

The study protocol was registered in the international prospective register of systematic reviews Prospero (CRD42019148745). A literature search (in PubMed, Embase, The Cochrane Library, CINAHL and PsycINFO) up to 2021 February 16th yielded 2,423 studies. Two independent reviewers assessed eligibility and risk of bias.

RESULTS

Eighteen studies were eligible for the systematic review and 5 for the meta-analysis. Fourteen of the 18 studies were clinical treatment studies, and 4 were experimental studies specifically assessing placebo effects. The clinical treatment studies provided varying evidence for placebo effects in chronic LBP but insufficient evidence for acute and subacute LBP. Most experimental studies investigating chronic LBP revealed significant placebo effects. The meta-analysis of 5 treatment studies investigating chronic LBP depicted a significant moderate effect size of placebo for pain intensity (SMD = 0.57) and disability (SMD = 0.52).

CONCLUSIONS

This review shows a significant contribution of placebo effects to chronic LBP symptom relief in clinical and experimental conditions. The meta-analysis revealed that placebo effects can influence chronic LBP intensity and disability. However, additional studies are required for more supporting evidence and evidence for placebo effects in acute or subacute LBP.

SIGNIFICANCE

This systematic review and meta-analysis provides evidence of true placebo effects in low back pain (LBP). It shows a significant contribution of placebo effects to chronic LBP symptom relief. The results highlight the importance of patient- and context-related factors in fostering treatment effects in this patient group. New studies could provide insight into the potential value of actively making use of placebo effects in clinical practice.

Targeted Use of Placebo Effects Decreases Experimental Itch in Atopic Dermatitis Patients: A Randomized Controlled Trial

Evidence from pain research shows that the effectiveness of active pharmacological treatments can be enhanced by placebo effects. The "open drug administration" is superior to "hidden drug administration.​" In a randomized controlled trial, we aimed to show that the targeted use of placebo effects increases the efficacy of an antihistamine (dimetindene) infusion in participants with atopic dermatitis. We openly infused dimetindene (drug) in full sight with information (intervention group 1: OPEN-DRUG+INST), openly infused drug with an additional classical conditioning learning experience (intervention group 2: OPEN-DRUG+INST+COND) or infused drug without any information or sight (i.e., hidden administration (control group 1: HIDDEN-DRUG)). Control group 2 received a placebo infusion (saline) declared as dimetindene and also experienced the conditioning experience (PLAC+INST+COND). Itch was experimentally induced with histamine via a skin prick test. Outcome was assessed at the subjective (primary end point: experimental itch intensity, numeric rating scale), and objective level (secondary end point: wheal size, mm² ). Experimental-induced itch intensity decreased in all groups but at different rates (P < 0.001). The groups with the open administration, whether it was dimetindene or placebo, had significantly stronger reductions in itch compared to the HIDDEN-DRUG group (OPEN-DRUG+INST+COND: P < 0.001; OPEN-DRUG+INST: P = 0.009; and PLAC+INST+COND: P < 0.001). Additional drug conditioning mediated via expectation led to a stronger reduction of itching (P = 0.001). Results on wheal size were similar (P = 0.048), however, no significant difference between the HIDDEN-DRUG group and the PLAC+INST+COND group (P = 0.967) was found. We conclude that specifically generated targeted placebo effects can significantly increase the action of a drug (dimetindene) and should be used in clinical practice.

Peripheral nerve field stimulation in medically refractory trigeminal neuralgia attributed to multiple sclerosis

OBJECTIVE

Case reports and small patient series have suggested peripheral nerve field stimulation (PNFS) as a treatment for refractory trigeminal neuralgia attributed to multiple sclerosis (MS). Here, the authors aimed to assess the effects of this technique on long-term pain severity.

METHODS

Data were prospectively collected on patients with refractory trigeminal neuralgia attributed to MS who underwent PNFS between July 2013 and August 2017 at the authors' neurosurgical department. Patients were evaluated before and after the first treatment as well as at follow-up at least twice a year. Patients underwent assessment of their pain severity using the Barrow Neurological Institute (BNI) Scale before treatment and at follow-up and were questioned about adverse events following cranial MRI performed after implantation of a permanent PNFS system.

RESULTS

Eight patients (3 women) underwent PNFS trials and their median age was 61 years (IQR 73.75 - 46.5 years). Seven patients proceeded to permanent implantation of the stimulation system. At a median follow-up of 33 months (IQR 42 - 24 months), pain severity decreased from baseline to the last follow-up (BNI score decrease from V [IQR V - V] to III [IQR V - III], p = 0.054). Four patients experienced long-lasting benefit (at 48, 33, 24, and 15 months' follow-up, respectively), while in 3 patients the treatment eventually failed after an initially successful period. One patient had an infection, requiring system removal and subsequent reimplantation. No other complications occurred. No adverse events were noted in the patients undergoing MRI postimplantation.

CONCLUSIONS

This analysis indicates a possibly beneficial long-term effect of PNFS on refractory trigeminal neuralgia attributed to MS in some patients.

The placebo phenomenon and the underlying mechanisms

The clinical role of the placebo effect is a topic of increasing interest for the scientific community. Focus is shifting from the inert role of placebos in randomized controlled trials (RCTs) to potential effects in clinical applications, since the phenomenon is thought to be inherent in routine clinical practice, affecting therapy success rates. Mediation of the mind-brain-body relationship involves both psychosocial and neurobiological factors, the interaction of which comprises the placebo mechanisms. Psychosocial factors include environmentally induced expectations, reward expectations, and even conditioned responses to certain stimuli. Expectations also depend on previous experience of the patient with a similar procedure and can affect future responses. Moreover, the supportive bedside behavior of the clinician and the positive framing of information provided to the patient have proven to be of great importance, setting the foundations for reconsideration of standardized practices. Neurobiological mechanisms mediate these effects through neurotransmitter and neuromodulator pathways. The best understood mechanisms are those regulating non-opioid- and opioid-mediated analgesic responses that implicate specific brain regions of pain control and activation of endogenous opioids. Other responses concern, among others, hormonal control, motor performance, and antidepressant responses. Although mechanisms underlying placebo responses are not as yet completely elucidated, there is substantial evidence suggesting that placebo effects are indicative of healthy functioning of intact brain structures and occur through actual functional changes, and are not simply subjective symptom reports. These effects can be utilized in treatment optimization while maintaining an ethical and respectful manner toward the patient and the standardized disclosure procedures.

The Effect of Temporal Information on Placebo Analgesia and Nocebo Hyperalgesia

OBJECTIVE

Expectations are known to be key determinants of placebo and nocebo phenomena. In previous studies, verbal suggestions to induce such expectations have mainly focused on the direction and magnitude of the effect, whereas little is known about the influence of temporal information.

METHODS

Using an experimental placebo and nocebo design, we investigated whether information about the expected onset of a treatment effect modulates the start and time course of analgesic and hyperalgesic responses. Healthy volunteers (n = 166) in three placebo and three nocebo groups were informed that the application of an (inert) cream would reduce (placebo groups) or amplify pain (nocebo groups) after 5, 15, or 30 minutes. Two control groups were also included (natural history and no expectations). Participants' pain intensity rating of electrical stimuli administered before and 10, 20, and 35 minutes after cream application was obtained.

RESULTS

Mixed-method analysis of variance showed a significant interaction between group and time (F(12,262) = 18.172, p < .001, pη2 = 0.454), suggesting that pain variations differed across time points and between groups. Post hoc comparisons revealed that the placebo and nocebo groups began to show a significantly larger change in perceived pain intensity than the no-expectancy control group at the expected time point (p < .05) but not earlier (p > .05). Once triggered, the analgesic effect remained constant over the course of the experiment, whereas the hyperalgesic effect increased over time.

CONCLUSIONS

Our results indicate that temporal suggestions can shape expectancy-related treatment effects, which, if used systematically, could open up new ways to optimize treatment outcome.

The pharmacological management of chronic lower back pain

INTRODUCTION

Treating chronic low back pain (LBP) can be challenging, and the most effective pharmacological therapy is controversial. The present systematic review investigated the efficacy of various pharmacological compounds to achieve pain relief and improve disability in chronic LBP patients. The present study focused on acetaminophen, amoxicillin, flupirtine, baclofen, tryciclic antidepressants (TCAs), duloxetine, topiramate, gabapentinoids, non-steroid anti-inflammatory drugs (NSAIDs) and opioids.

AREAS COVERED

All randomized clinical trials comparing two or more drug treatments for chronic low back pain were accessed. Studies reporting outcomes concerning patients with neurologic or mechanic, specific or aspecific low back pain with or without radiculopathy were included. LBP was considered chronic if pain had lasted more than 6 weeks. Data from 47 articles (9007 patients: mean age: 52.62 ± 7.0 years; mean BMI: 28.26 ± 2.8; mean follow-up: 3.23 ± 3.2 months) were obtained.

EXPERT OPINION

According to published level I evidence, only baclofen, duloxetine, NSAIDs, and opiates showed to improve pain and disability levels in patients with LBP. However, the patients' demographics are heterogeneous, and the results must be interpreted with caution and in the light of possible adverse events connected to the use of these drugs.

[Placebo effects in pain therapy]

In the past few decades, research on pain and placebo analgesia has gained importance both scientifically and clinically. In this article, the current findings and focus of research as well as the significance of placebo research for assessing the effectiveness of pain medication are illustrated. The underlying mechanisms of placebo analgesia not only have implications for theoretical models but also offer clinically relevant guidelines for everyday interventions in pain treatment. However, many placebo phenomena are not fully understood and have to be investigated further in order to exploit the full potential of placebo effects. Interindividual differences and their inclusion in treatment will play a major role in this aspect.

Placebo effects in pain

Placebo effects influence symptom perceptions and treatment outcomes. Placebo effects can be explored in laboratory settings controlling for natural history and expectations. Such a mechanistic approach to neurological disorders has been implemented in the domain of chronic clinical pain and other neurological disorders. This article therefore focuses on definitions and historical notes related to placebo effects and mechanisms of placebo effects in chronic pain. Knowledge on mechanisms of placebo effects could inform current clinical practice for the treatment of neurological disorders by focusing on patients (and providers) expectations for outcome optimization.

Positive Treatment Expectancies Reduce Clinical Pain and Perceived Limitations in Movement Ability Despite Increased Experimental Pain: A Randomized Controlled Trial on Sham Opioid Infusion in Patients with Chronic Back Pain

BACKGROUND

Increasing evidence for the efficacy of analgesic placebo effects in laboratory studies with healthy persons raises the question whether placebos could be used to improve the treatment of pain patients. Expectancies play a central role in shaping analgesic placebo but also nocebo effects.

OBJECTIVES

We investigated to what extent a sham opioid infusion (saline solution) produces sustained clinically relevant placebo and nocebo effects in chronic back pain patients.

METHODS

Fifty-nine patients received the sham opioid infusion applied via a large drain dressing and were compared to 14 control patients without intervention (natural history, NH) while experimental pain stimuli were applied. All subjects were told that the infusion would decrease pain although in rare cases pain increase would be possible (induction of expectancy). In addition, conditioning was introduced where the participants either experienced a decrease in experimental pain (n = 17; placebo conditioning), an increase (n = 21; nocebo conditioning), or no change (n = 21, no conditioning).

RESULTS

Compared to the NH group, all infusion groups showed positive treatment expectancies and significantly (p < 0.001) reduced clinical back pain (primary outcome) and pain-related disability (secondary outcome, assessed by self-reported functional capacity and perceived impairment of mobility). Even the nocebo conditioned group experiencing increased experimental pain developed positive treatment expectancies followed by reduced pain experience. Positive treatment expectancies and relief in clinical back pain were significantly positively correlated (r = 0.72, p < 0.01).

CONCLUSIONS

These findings suggest that it may be beneficial to explicitly shape and integrate treatment expectancies into clinical pain management.

The Association Between Daily Physical Activity and Pain Among Patients with Knee Osteoarthritis: The Moderating Role of Pain Catastrophizing

OBJECTIVE

The primary objective of this study was to examine the day-to-day association between physical activity and pain intensity among a sample of patients with knee osteoarthritis (KOA) and the potential moderation of this association by negative cognitive processes.

METHODS

In this micro-longitudinal daily diary study, KOA patients (N = 121) completed questionnaires assessing pain (Brief Pain Inventory) and psychosocial functioning (pain catrophizing scale, WOMAC McMaster Universities Osteoarthritis Index function, Patient-Reported Outcomes Measurement Information System [PROMIS; anxiety and depression], the Godin-Shephard Leisure-Time Physical Activity questionnaire, the six-minute walking test) and were then asked to report their levels of physical activity and pain intensity once per day for a period of seven days using an electronic diary.

RESULTS

Multilevel modeling analyses indicated that day-to-day increases in physical activity were associated with heightened levels of pain intensity (B = 0.13 SE = 0.03, P < 0.001). In addition, it was revealed that the association between physical activity and pain intensity was moderated by catastrophizing (B = -0.01 SE = 0.002, P < 0.05), with patients scoring higher in catastrophizing showing a relatively stronger link between day-to-day physical activity and increased knee pain. This effect was specific to catastrophizing, as depression and anxiety did not moderate the activity-pain relationship (P > 0.05).

CONCLUSIONS

Our findings suggest that increases in daily physical activity are associated with concurrent increases in KOA patients' levels of knee pain, particularly among patients reporting higher levels of pain catastrophizing. These results may have clinical implications for the design and testing of interventions targeted at reducing catastrophizing and increasing physical activity among patients with chronic osteoarthritis pain.

Pain Response to Open Label Placebo in Induced Acute Pain in Healthy Adult Males

Background

Open label placebos with patient education are effective in reducing chronic pain, and recent studies on their effect on pain have established interest in this field. Nevertheless, data on their effect on acute pain are scarce, and on hyperalgesia and allodynia, absent. This study assessed the effect of open label placebos on acute pain in healthy adult males and the influence of placebo education.

Methods

Thirty-two healthy males were included in this prospective, randomized, assessor-blinded crossover, single-center study assessing pain intensities (via numeric rating scale), area of hyperalgesia (von Frey filament), and allodynia (dry cotton swab) in a pain model utilizing intracutaneous electrical stimulation. The authors compared the effect of intravenous open label placebo on pain compared to no treatment. The authors further examined the effect of placebo on hyperalgesia and allodynia, and the influence of education (short vs. detailed) before placebo application. Saliva cortisol concentrations were also measured.

Results

Pain ratings (median, first to third quartile) were 21% lower during placebo treatment compared to no treatment, 4.0 (3.2 to 4.9) versus 5.1 (4.7 to 5.4), respectively (P = 0.001). The areas of hyperalgesia and allodynia were lower during placebo treatment compared to no treatment (hyperalgesia, 30 cm2 [17 to 47] vs. 55 cm2 [42 to 68], P = 0.003; allodynia, 24 cm2 [11 to 39] vs. 45 cm2 [31 to 62], P = 0.007). This corresponds to reductions of 47%. The extent of placebo education had no effect on pain. Saliva cortisol decreased significantly over time and was under the limit of detectability in the majority of participants in postbaseline measurements in both treatment branches. Baseline cortisol was not associated with the placebo effect or strength applied of current to reach defined pain ratings.

Conclusions

Open label placebos might play a role in multimodal analgesic concepts.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Modeling Learning Patterns to Predict Placebo Analgesic Effects in Healthy and Chronic Orofacial Pain Participants

Successfully predicting the susceptibility of individuals to placebo analgesics will aid in developing more effective pain medication and therapies, as well as aiding potential future clinical use of placebos. In pursuit of this goal, we analyzed healthy and chronic pain patients' patterns of responsiveness during conditioning rounds and their links to conditioned placebo analgesia and the mediating effect of expectation on those responses. We recruited 579 participants (380 healthy, 199 with temporomandibular disorder [TMD]) to participate in a laboratory placebo experiment. Individual pain sensitivity dictated the temperatures used for high- and low-pain stimuli, paired with red or green screens, respectively, and participants were told there would be an analgesic intervention paired with the green screens. Over two conditioning sessions and one testing session, participants rated the painfulness of each stimulus on a visual analogue scale from 0 to 100. During the testing phase, the same temperature was used for both red and green screens to assess responses to the placebo effect, which was defined as the difference between the average of the high-pain-cue stimuli and low-pain-cue stimuli. Delta scores, defined as each low-pain rating subtracted from its corresponding high-pain rating, served as a means of modeling patterns of conditioning strength and placebo responsiveness. Latent class analysis (LCA) was then conducted to classify the participants based on the trajectories of the delta values during the conditioning rounds. Classes characterized by persistently greater or increasing delta scores during conditioning displayed greater placebo analgesia during testing than those with persistently lower or decreasing delta scores. Furthermore, the identified groups' expectation of pain relief acted as a mediator for individual placebo analgesic effects. This study is the first to use LCA to discern the relationship between patterns of learning and the resultant placebo analgesia in chronic pain patients. In clinical settings, this knowledge can be used to enhance clinical pain outcomes, as chronic pain patients with greater prior experiences of pain reduction may benefit more from placebo analgesia.

A test of psychological and electrodermal changes immediately after the delivery of 3 analgesic treatment messages

Introduction:

Placebo analgesia often results when a pain reduction treatment message is delivered to a patient or research participant. Little information exists regarding the psychological changes that are immediately triggered by the delivery of a treatment message.

Objectives:

This experiment tested the impact of 3 different analgesic treatment messages on the expectations, feelings, and electrodermal activity of participants anticipating a pain stimulus.

Methods:

In laboratory sessions, healthy participants (N = 138) were randomly assigned to 1 of 4 conditions in a between-subject design. The design included a no treatment message control condition and 3 treatment message conditions: a standard analgesic message, an analgesic treatment with side-effect message, and a double-blind analgesic message. After the treatment message manipulation, measures were taken of: treatment efficacy expectations, pain experience expectations, pretask anxiety, positive affect, negative affect, and electrodermal activity.

Results:

Overall, the dependent measures showed relatively few correlations. Furthermore, across all 3 message conditions, treatment-specific expectations were greatly increased compared with the control condition. Finally, participants in the double-blind message condition displayed elevated negative affect.

Conclusion:

All 3 analgesic treatment messages produced a stronger immediate influence on treatment efficacy expectations than on the other dependent measures. Treatment messages can alter negative affect along with expectancies. The low correlations found between dependent measures suggest that different patterns of psychological responses may emerge from analgesic treatment messages depending on contextual factors.

Psychobiological Mechanisms of Placebo and Nocebo Effects: Pathways to Improve Treatments and Reduce Side Effects

Placebo effects constitute a major part of treatment success in medical interventions. The nocebo effect also has a major impact, as it accounts for a significant proportion of the reported side effects for many treatments. Historically, clinical trials have aimed to reduce placebo effects; however, currently, there is interest in optimizing placebo effects to improve existing treatments and in examining ways to minimize nocebo effects to improve clinical outcome. To achieve these aims, a better understanding of the psychological and neurobiological mechanisms of the placebo and nocebo response is required. This review discusses the impact of the placebo and nocebo response in health care. We also examine the mechanisms involved in the placebo and nocebo effects, including the central mechanism of expectations. Finally, we examine ways to enhance placebo effects and reduce the impact of the nocebo response in clinical practice and suggest areas for future research.

Evidence-Based Pain Management: Building on the Foundations of Cochrane Systematic Reviews

We discuss the history and current status of evidence-based medicine for the prevention and treatment of acute and chronic pain as it has developed in the Cochrane Collaboration's Pain, Palliative and Supportive Care Review Group.To date, the Pain, Palliative and Supportive Care Review Group has published 277 reviews and a further 11 reviews of systematic reviews summarizing the evidence for interventions. The Cochrane Library has readily available high-quality summaries of evidence of pharmacological interventions especially for postsurgical pain but also for chronic musculoskeletal and neuropathic pain. The library covers all forms of intervention, not only pharmacological.The world of evidence-based medicine is changing: most historical trials have been entered into reviews, but the evidence is still not well disseminated and needs to be better translated into decision support. Evidence should be at the heart of policymaking. Much has been achieved in the past 21 years, but there are no grounds for complacency.

Orthopedic Professionals' Recognition and Knowledge of Pain and Perceived Barriers to Optimal Pain Management at Five Hospitals

Pain is a challenge for orthopedic healthcare professionals (OHCP). However, pain studies examined the competencies of a single OHCP category, did not consider various pain management domains or barriers to optimal pain service, and are deficient across the Arabic Eastern Mediterranean region. We surveyed OHCP's recognition and knowledge of pain and perceived barriers to optimal pain service (361 OHCP, five hospitals). Chi square compared doctors' (n = 63) vs. nurses/physiotherapists' (n = 187) views. In terms of pain recognition, more nurses had pain management training, confidently assessed pediatric/elderly pain, were aware of their departments' pain protocols, and felt that their patients receive proper pain management. More doctors comfortably prescribed opiate medications and agreed that some nationalities were more sensitive to pain. For pain knowledge, more nurses felt patients are accurate in assessing their pain, vital signs are accurate in assessing children's pain, children feel less pain because of nervous system immaturity, narcotics are not preferred due respiratory depression, and knew pre-emptive analgesia. As for barriers to optimal pain service, less nurses agreed about the lack of local policies/guidelines, knowledge, and skills; time to pre-medicate patients; knowledge about medications; complexity of the clinical environment; and physicians being not comfortable prescribing pain medication. We conclude that doctors required confidence in pain, especially pediatric and geriatric pain, using vital signs in assessing pain and narcotics use. Their most perceived barriers were lack of local policies/guidelines and skills. Nurses required more confidence in medications, caring for patients on narcotics, expressed fewer barriers than doctors, and the complexity of the clinical environment was their highest barrier. Educational programs with clinical application could improve OHCPs' pain competencies/clinical practices in pain assessment and administration of analgesics.

Clinical Use of Placebo Effects in Patients With Pain Disorders

The analgesic placebo effect is well documented by numerous studies. Many important influencing factors, however, are yet to be discovered. In the arena of placebo effects and clinical implications, expectancies play a central role. Expectancies are shaped by processes of classical and social learning as well as verbal instructions and are strongly related to emotional factors. Expectancies trigger a cascade of endogenous opioids and non-opioids, which alter the experience of pain. For clinical application it is important to know, that placebo research yields ethical possibilities to use placebo effects without deception and without using placebos. Since placebo effects contribute to responses to active analgesics, it is feasible to enhance patients' benefits from pain treatments by increasing the additional placebo effect. There are several possibilities to use the placebo effects via shaping and adapting information about analgesic medication and via associating medication intake with a positive context. A positive patient-clinician communication atmosphere is very important to generate clinically meaningful placebo effects in pain medicine.

Implications of Placebo and Nocebo Effects for Clinical Practice: Expert Consensus

BACKGROUND

Placebo and nocebo effects occur in clinical or laboratory medical contexts after administration of an inert treatment or as part of active treatments and are due to psychobiological mechanisms such as expectancies of the patient. Placebo and nocebo studies have evolved from predominantly methodological research into a far-reaching interdisciplinary field that is unravelling the neurobiological, behavioural and clinical underpinnings of these phenomena in a broad variety of medical conditions. As a consequence, there is an increasing demand from health professionals to develop expert recommendations about evidence-based and ethical use of placebo and nocebo effects for clinical practice.

METHODS

A survey and interdisciplinary expert meeting by invitation was organized as part of the 1st Society for Interdisciplinary Placebo Studies (SIPS) conference in 2017. Twenty-nine internationally recognized placebo researchers participated.

RESULTS

There was consensus that maximizing placebo effects and minimizing nocebo effects should lead to better treatment outcomes with fewer side effects. Experts particularly agreed on the importance of informing patients about placebo and nocebo effects and training health professionals in patient-clinician communication to maximize placebo and minimize nocebo effects.

CONCLUSIONS

The current paper forms a first step towards developing evidence-based and ethical recommendations about the implications of placebo and nocebo research for medical practice, based on the current state of evidence and the consensus of experts. Future research might focus on how to implement these recommendations, including how to optimize conditions for educating patients about placebo and nocebo effects and providing training for the implementation in clinical practice.

Placebo hypoalgesic effects in pain: Potential applications in dental and orofacial pain management

Placebo and nocebo effects are present within every treatment and intervention, and can be purposefully enhanced and reduced, respectively, in order to improve patients' clinical outcomes. A plethora of research has been conducted on the mechanisms of placebo hypoalgesia and nocebo hyperalgesia in experimental and clinical settings. However, its implications in particular clinical settings such as orthodontic pain management remain underexplored. We conducted a search of the literature regarding placebo analgesia, orthodontic pain management, and orofacial and dental pain. Articles were qualitatively assessed and selected based on the scope of this narrative review. Although no studies investigating the extent of the implications of the placebo and nocebo phenomena in the orthodontic clinical setting were found, we herein present a comprehensive review on the influences of placebo and nocebo effects in experimental and clinical pain management, as well as on the potential for engaging placebo-related endogenous pain modulation for orthodontic pain management. Ethical considerations for the clinical application of placebos are discussed, and future research directions are presented.

The Underestimated Significance of Conditioning in Placebo Hypoalgesia and Nocebo Hyperalgesia

Placebo and nocebo effects are intriguing phenomena in pain perception with important implications for clinical research and practice because they can alleviate or increase pain. According to current theoretical accounts, these effects can be shaped by verbal suggestions, social observational learning, and classical conditioning and are necessarily mediated by explicit expectation. In this review, we focus on the contribution of conditioning in the induction of placebo hypoalgesia and nocebo hyperalgesia and present accumulating evidence that conditioning independent from explicit expectation can cause these effects. Especially studies using subliminal stimulus presentation and implicit conditioning (i.e., without contingency awareness) that bypass the development of explicit expectation suggest that conditioning without explicit expectation can lead to placebo and nocebo effects in pain perception. Because only few studies have investigated clinical samples, the picture seems less clear when it comes to patient populations with chronic pain. However, conditioning appears to be a promising means to optimize treatment. In order to get a better insight into the mechanisms of placebo and nocebo effects in pain and the possible benefits of conditioning compared to explicit expectation, future studies should carefully distinguish both methods of induction.