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.

Pain experience in eating disorders: The mediating role of depression, alexithymia and interoceptive awareness.

OBJECTIVE: Evidence suggests reduced sensitivity to pain due to high pain threshold in anorexia and bulimia nervosa and a possible role of depression, alexithymia and interoceptive awareness on pain experience. This study examined whether self-report and real-time evoked pain experience were mediated by depression, alexithymia and interoceptive awareness in a comprehensive sample of patients with eating disorders (ED). METHOD: 145 participants (90 ED, 55 healthy controls (HC)) underwent a real-time evoked examination of pain and completed self-report questionnaires for pain (Pain Detect Questionnaire (PD-Q), PD-Q VAS, Leeds Assessment of Neuropathic Symptoms and Signs), depression (BDI-II), interoceptive awareness Multidimensional Assessment of Interoceptive Awareness (MAIA), and alexithymia (TAS-20). Three mediation models, with ED diagnosis as independent variable, and BDI, MAIA and TAS-20 as mediators, were tested. RESULTS: Participants with ED and HC exhibited similar pain type and intensity (self-report and real-time). Eating disorders diagnosis was associated with lower self-report pain intensity and non-neuropathic like pain experience (model 1-2). Depressive symptoms partially (model 1-2) or fully (model 3) mediated the association between ED diagnosis and pain experience, alone (model 1) or via alexithymia (model 3). Interoceptive awareness did not influence pain symptomatology. DISCUSSION: ED diagnosis is associated with non-neuropathic and lower pain experience. However, concurrent depression and alexithymia are associated with higher pain symptoms and neuropathic features. These results could inform clinicians about the influence of psychopathology on pain experience in ED.

Medical Extended Reality Trials: Building Robust Comparators, Controls, and Sham.

The explosive pace of development and research in medical extended reality (MXR) is a testament to its promise for health care and medicine. In comparison with this growth, there is a relative sparsity of rigorous clinical trials that establish the efficacy and effectiveness of these interventions. Explicating mechanisms of action across clinical areas and MXR applications is another major area of need. A primary impediment to these goals is a lack of frameworks for trial design, more specifically, the selection of appropriate controls that effectively address unique elements of MXR. This paper delineates a framework for designing controls, sham conditions, and comparators, as well as proposed considerations for MXR trial designs. Special consideration is given to the design of sham conditions. Improved designs would enable more robust findings and the development of generalizable knowledge that could be adopted across MXR interventions.

Motivating older adults through immersive virtual exercise (MOTIVE): A randomized pilot study.

BACKGROUND: This study aimed to: 1) determine the feasibility of a virtual reality physical activity intervention among older adults and 2) test the preliminary effectiveness of the intervention at increasing physical activity and 3) decreasing depressive symptoms. METHODS: We included 10 older adults randomized into the Motivating Older Adults Through Immersive Virtual Exercise (MOTIVE) intervention group and 10 randomized into the physical activity education only control group. We analyzed the data using descriptive statistics and linear mixed models, testing the interaction of time and the treatment condition. RESULTS: Participants in the intervention group attended an average of 15 out of the 16 sessions. A total of 90% of MOTIVE intervention group participants "completely agreed" that the intervention was acceptable, (compared to 30% of education control group participants). CONCLUSION: This study supports testing the effectiveness of the intervention at improving physical activity and depressive symptoms in a larger sample of older adults.

The Placebo Effect in Pain Therapies.

Pharmacological strategies for pain management have primarily focused on dampening ascending neurotransmission and on opioid receptor-mediated therapies. Little is known about the contribution of endogenous descending modulatory systems to clinical pain outcomes and why some patients are mildly affected while others suffer debilitating pain-induced dysfunctions. Placebo effects that arise from patients' positive expectancies and the underlying endogenous modulatory mechanisms may in part account for the variability in pain experience and severity, adherence to treatment, distinct coping strategies, and chronicity. Expectancy-induced analgesia and placebo effects in general have emerged as useful models to assess individual endogenous pain modulatory systems. Different systems and mechanisms trigger placebo effects that highly impact pain processing, clinical outcomes, and sense of well-being. This review illustrates critical elements of placebo mechanisms that inform the methodology of clinical trials, the discovery of new therapeutic targets, and the advancement of personalized pain management.

Engagement in Prescription Opioid Tapering Research: the EMPOWER Study and a Coproduction Model of Success.

Patients with chronic pain experience stigma within the healthcare system. This stigma is compounded for those taking long-term prescription opioids. Often, public messaging and organizational policies have telegraphed that opioid treatment is a problem to be solved by focusing only on medication reduction efforts. Lack of data has contributed to misperceptions and poor opioid policies. In part, data collection remains poor because patients feel fractured from systems of care and are often not interested in engaging with opioid reduction mandates and research. Similarly, clinicians may fail to engage with opioid stewardship and research due to complexities that exceed their training or capacities. The EMPOWER study applies a coproduction model that engages researchers, patients, clinicians, managers, and other health system users. Key stakeholders shaped the design of the study to best ensure acceptability and engagement of the "end users"-patients who enroll in the study and the clinicians who implement the opioid tapers. Targeting the needs of any stakeholder group in isolation is suboptimal. Accordingly, we detail the EMPOWER patient-centered opioid tapering clinical research framework and specific strategies to address stakeholder concerns. We also discuss how this framework may be applied to enhance engagement in healthcare research broadly.

Do Side Effects to the Primary COVID-19 Vaccine Reduce Intentions for a COVID-19 Vaccine Booster?

BACKGROUND: Vaccines are being administered worldwide to combat the COVID-19 pandemic. Vaccine boosters are essential for maintaining immunity and protecting against virus variants. The side effects of the primary COVID-19 vaccine (e.g., headache, nausea), however, could reduce intentions to repeat the vaccination experience, thereby hindering global inoculation efforts. PURPOSE: The aim of this research was to test whether side effects of a primary COVID-19 vaccine relate to reduced intentions to receive a COVID-19 booster. The secondary aim was to test whether psychological and demographic factors predict booster intentions. METHODS: Secondary data analyses were conducted on a U.S. national sample of 551 individuals recruited through the online platform Prolific. Key measures in the dataset were side effects reported from a primary COVID-19 vaccination and subsequent intentions to receive a booster vaccine. Psychological and demographic variables that predicted primary vaccination intentions in prior studies were also measured. RESULTS: Booster intentions were high. COVID-19 booster vaccine intentions were uncorrelated with the number of side effects, intensity of side effects, or occurrence of an intense side effect from the primary COVID-19 vaccine. Correlational and regression analyses indicated intentions for a booster vaccination increased with positive vaccination attitudes, trust in vaccine development, worry about the COVID-19 pandemic, low concern over vaccine side effects, and democratic political party affiliation. CONCLUSIONS: Side effects of a primary COVID-19 vaccine were not directly associated with lower intentions to receive a booster of the COVID-19 vaccine early in the pandemic. However, many variables that predict primary vaccination intentions also predict booster intentions.

Virtual reality for improving pain and pain-related symptoms in patients with advanced stage colorectal cancer: A pilot trial to test feasibility and acceptability.

OBJECTIVE: Virtual reality (VR) has the potential to improve pain and pain-related symptoms. We examined the feasibility, acceptability, safety, and impact of a 30-min virtual underwater/sea environment (VR Blue) for reducing pain and pain-related symptoms in advanced colorectal cancer patients. A qualitative exit interview was conducted to understand preferences, thoughts, and feelings about the VR session. METHOD: Participants (N = 20) had stage IV colorectal cancer and moderate-to-severe pain. Participants completed a 30-min VR Blue session that visually and aurally immersed them in virtual ocean scenarios. Feasibility was assessed by accrual (N = 20), protocol adherence (≥80% completing VR Blue), and completed data (≥80% assessment completion). Acceptability was determined by patients reporting ≥80% intervention satisfaction. Safety was determined by ≥80% of patients completing the session without self-reported side effects. Measures of pain, tension, relaxation, stress, anxiety, and mood were collected before, during, and after the VR Blue session. A semi-structured qualitative interview was conducted after VR Blue to assess participants' VR experiences. RESULTS: All participants (100%) completed the VR Blue session. There was 100% data collection at the pre- and post-assessments. Satisfaction with VR Blue was high M = 3.3 (SD = 0.4) (83%). No significant side effects were reported. Pain decreased by 59% (Pre-M = 3 [1]; Post-M = 1 [1]). Tension decreased by 74% (Pre-M = 30 [24]; Post-M = 8 [13]). Relaxation improved by 38% (Pre-M = 62 [21]); Post-M = 86 [17]). Stress decreased by 68% (Pre-M = 24 [24]; Post-M = 8 [14]). Anxiety decreased by 65% (Pre-M = 20 [23]; Post-M = 7 [13]). Mood improved by 70% (Pre-M = 13 [16]; Post-M = 4 [11]). Qualitative data suggested a positive response to the VR Blue protocol. SIGNIFICANCE OF RESULTS: This work supports the feasibility, acceptability, and safety of VR Blue for advanced colorectal cancer patients. Participants showed significant pre-post improvement in pain and pain-related symptoms hinting to the potential feasibility of VR interventions in this population. Larger, randomized trials with a control condition are needed to examine the efficacy of VR-based interventions for patients with advanced colorectal cancer and pain.

Ethnic Differences in Experimental Pain Responses Following a Paired Verbal Suggestion With Saline Infusion: A Quasiexperimental Study.

BACKGROUND: Ethnic differences in placebo and nocebo responses are an important, yet underresearched, patient factor that might contribute to treatment disparities. PURPOSE: The purpose of this study was to examine ethnic differences in pain trajectories following a verbal suggestion paired with a masked, inert substance (i.e., saline). METHODS: Using a quasiexperimental design, we examined differences between 21 non-Hispanic Black (NHB) participants and 20 non-Hispanic White (NHW) participants in capsaicin-related pain rating trajectories following a nondirectional verbal suggestion + saline infusion. All participants were told that the substance would "either increase pain sensation, decrease it, or leave it unchanged." A spline mixed model was used to quantify the interaction of ethnicity and time on ratings. RESULTS: There was a significant Ethnicity × Time interaction effect (ß = -0.28, p = .002); NHB individuals reported significantly greater increases in pain following, but not before, the verbal suggestion + saline infusion. Sensitivity analyses showed no change in primary results based on differences in education level, general pain sensitivity, or condition order. CONCLUSIONS: The present results showed ethnic differences in pain response trajectories following a verbal suggestion + saline infusion and suggest that future research rigorously examining possible ethnic differences in placebo/nocebo responses is warranted.

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.

Patient and Provider Acceptability of a Patient Preauthorized Concealed Opioid Reduction.

OBJECTIVE: Limited research of how to best taper opioids brings about an ethical and clinical dilemma. Experiments using overt and concealed administration of opioids have demonstrated the benefits of a concealed reduction to eliminate negative expectations and prolong analgesic benefits. This may allow for opioid tapering without significant increases in pain. Based on this, we investigated patient and provider acceptance of a concealed opioid reduction for chronic pain. METHODS: We conducted a cross-sectional survey via REDcap with 74 patients, who are currently taking or have taken high dose opioids, and 49 providers using a validated questionnaire based on two hypothetical clinical trials comparing a patient preauthorized concealed opioid reduction vs standard tapering. RESULTS: We found that patients and providers have positive attitudes toward a concealed reduction of opioid dosages. More than 60% of providers and patients surveyed viewed the hypothetical clinical trial as helpful to reduce pain, side effects, and withdrawal symptoms. Sixty-one percent of patients and 77.6% of providers recognized that there would be differences in pain relief depending upon which group the hypothetical participants would be enrolled in. CONCLUSIONS: Patients and providers appear to understand the benefits of a concealed opioid reduction. Our findings support future randomized controlled trials that compare concealed and overt opioid tapering in patients with chronic pain. More research is needed to understand the difference in attitudes between research and clinical practice and to test the acceptability of a concealed reduction following a participation in an active clinical trial.

The neural processes of acquiring placebo effects through observation.

Learning through social observation is critical for humans. The present study investigates the neural processes underlying the acquisition of placebo effects through observational learning. We created a new functional magnetic resonance imaging (fMRI) paradigm where participants (n â€‹= â€‹38, healthy, both sexes) observed a demonstrator experiencing pain relief by a placebo treatment cream and experiencing pain without a treatment (control cream), and subsequently performed the same procedure themselves. Participants demonstrated placebo hypoalgesia while they performed the procedure themselves, confirming that observational learning can lead to placebo effects. During the observational learning phase, fMRI analysis showed a modulation of the amygdalae, periaqueductal grey, temporoparietal junctions (TPJ), and dorsolateral prefrontal cortex (DLPFC). Connectivity between the DLPFC and TPJ during the observational learning task was modulated by the placebo treatment and predicted subsequent placebo effects. Mediation analysis further confirmed that the DLPFC-TPJ connectivity formally mediated the effect of the observed treatment condition on subsequent placebo effects. Additionally, pre-recorded resting state connectivity between the DLPFC and TPJ also predicted observationally-learned placebo effects. Our findings provide an understanding of the neural processes during the acquisition of placebo effects through observation and indicate a critical role for DLPFC-TPJ integration processes during observational learning of therapeutic outcomes.

Merely Possessing a Placebo Analgesic Improves Analgesia Similar to Using the Placebo Analgesic.

BACKGROUND: Placebo analgesia studies generally reported that the actual use of a placebo analgesic reduces pain. Yeung, Geers, and Kam found that the mere possession (without use) of a placebo analgesic also reduces pain. PURPOSE: We investigated the relative effectiveness of using versus possessing a placebo analgesic on pain outcomes. METHODS: In Study 1a, 120 healthy adults were randomized to either the experimental (EXP) conditions (EXP1: used a placebo analgesic cream, EXP2: possessed a placebo analgesic cream) or control (CO) conditions (CO1: possessed a sham cream, CO2: no cream). All participants underwent a cold pressor test (CPT). Study 1b further delineated the effect of possession from the effect of use. Sixty healthy adults were randomized to either the placebo-possession condition (merely possessed a placebo analgesic cream) or the placebo-possession-use condition (possessed and used a placebo analgesic cream). All participants did a CPT. RESULTS: In Study 1a, as expected, a placebo effect was found-participants who used a placebo analgesic cream showed better pain outcomes than the two CO groups. Surprisingly, participants who merely possessed a placebo analgesic cream performed equally well as those who actually used it. In Study 1b, participants in the two conditions did not differ in most pain outcomes. Participants who possessed and used a placebo analgesic cream only showed slightly more reduction in pain intensity compared to participants who merely possessed the placebo analgesic cream. CONCLUSIONS: Our results suggest that merely possessing a placebo analgesic could enhance pain outcomes similar to that of applying the placebo analgesic.

Prior Therapeutic Experiences, Not Expectation Ratings, Predict Placebo Effects: An Experimental Study in Chronic Pain and Healthy Participants.

INTRODUCTION: Many clinical trials fail because of placebo responses. Prior therapeutic experiences and patients' expectations may affect the capacity to respond to placebos in chronic disorders. OBJECTIVE: The scope of this study in 763 chronic orofacial pain and healthy study participants was to compare the magnitude and prevalence of placebo effects and determine the putative role of prior therapeutic experiences vs. expectations. METHODS: We tested placebo propensity in a laboratory setting by using 2 distinct levels of individually tailored painful stimulations (high pain and low pain) to reinforce expectations and provide a hypoalgesic experience (conditioning phase). Afterwards, both levels of pain were surreptitiously set at a moderate pain level to test for placebo effects (testing phase). Pain and expectation ratings were assessed as primary outcomes using visual analog scales. RESULTS: In both chronic pain and healthy participants, placebo effects were similar in magnitude, with the larger prevalence of responders in the healthy participants. Although chronic pain participants reported higher pain relief expectations, expectations did not account for the occurrence of placebo effects. Rather, prior experience via conditioning strength mediated placebo effects in both pain and healthy participants. CONCLUSIONS: These findings indicate that participants with chronic pain conditions display robust placebo effects that are not mediated by expectations but are instead directly linked to prior therapeutic experiences. This confirms the importance of assessing the therapeutic history while raising questions about the utility of expectation ratings. Future research is needed to enhance prediction of responses to placebos, which will ultimately improve clinical trial designs.

Attitudes and Perceptions Toward Authorized Deception: A Pilot Comparison of Healthy Controls and Fibromyalgia Patients.

OBJECTIVE: Little is known about the perceptions and attitudes of participants who volunteer in studies involving authorized deception. Thus, this cross-sectional pilot study measured, for the first time, the perceptions about participation in an authorized-deception placebo analgesia study in chronic pain patients with fibromyalgia and assessed whether their perceptions differed from healthy controls. METHODS: An anonymous survey with questions about trust in research and willingness to participate in future research involving deception was mailed to participants in both groups after completion of the parent study. Statistical analyses were performed using the Mann-Whitney U and chi-square tests (31 controls and 16 fibromyalgia patients were included in the analyses). RESULTS: The majority of participants expressed little or no concern about the deception, still trusted the scientific process, and found the debriefing procedure helpful and worthwhile. Group differences were found in willingness to 1) participate in the parent study had the deceptive element been disclosed in advance (controls = definitely, fibromyalgia patients = probably, U = 341.5, P = 0.01) and 2) participate in future studies (controls = definitely, fibromyalgia patients = probably, U = 373, P < 0.001). CONCLUSIONS: Despite slightly less favorable responses of fibromyalgia patients and the relatively small size of the study, these findings suggest that attitudes and perceptions about participating in an authorized placebo study remain positive in both healthy and chronic pain populations.

Comparative Effectiveness of Cognitive Behavioral Therapy for Chronic Pain and Chronic Pain Self-Management within the Context of Voluntary Patient-Centered Prescription Opioid Tapering: The EMPOWER Study Protocol.

OBJECTIVE: Evidence to date, while sparse, suggests that patients taking long-term opioids require special considerations and protections to prevent potential iatrogenic harms from opioid de-prescribing, such as increased pain or suffering. Following this study protocol, the EMPOWER study seeks to address multiple unmet needs of patients with chronic pain who desire to reduce long-term opioid therapy, and provide the clinical evidence on effective methodology. METHODS: EMPOWER applies patient-centered methods for voluntary prescription opioid reduction conducted within a comprehensive, multi-state, 3-arm randomized controlled comparative effectiveness study of three study arms (1) group cognitive behavioral therapy for chronic pain; (2) group chronic pain self-management; and (3) usual care (taper only). Specialized electronic data capture systems collect patient reported symptoms and satisfaction data weekly and monthly during the taper, with real-time clinical alerts and electronic feedback loops informing, documenting, and steering needed care actions. CONCLUSION: The EMPOWER study seeks to provide granular evidence on patient response to voluntary opioid tapering, and will provide evidence to inform clinical systems changes, clinical care, patient satisfaction, and patient outcomes for opioid reduction.

Behavioral, Physiological and EEG Activities Associated with Conditioned Fear as Sensors for Fear and Anxiety.

Anxiety disorders impose substantial costs upon public health and productivity in the USA and worldwide. At present, these conditions are quantified by self-report questionnaires that only apply to behaviors that are accessible to consciousness, or by the timing of responses to fear- and anxiety-related words that are indirect since they do not produce fear, e.g., Dot Probe Test and emotional Stroop. We now review the conditioned responses (CRs) to fear produced by a neutral stimulus (conditioned stimulus CS+) when it cues a painful laser unconditioned stimulus (US). These CRs include autonomic (Skin Conductance Response) and ratings of the CS+ unpleasantness, ability to command attention, and the recognition of the association of CS+ with US (expectancy). These CRs are directly related to fear, and some measure behaviors that are minimally accessible to consciousness e.g., economic scales. Fear-related CRs include non-phase-locked phase changes in oscillatory EEG power defined by frequency and time post-stimulus over baseline, and changes in phase-locked visual and laser evoked responses both of which include late potentials reflecting attention or expectancy, like the P300, or contingent negative variation. Increases (ERS) and decreases (ERD) in oscillatory power post-stimulus may be generalizable given their consistency across healthy subjects. ERS and ERD are related to the ratings above as well as to anxious personalities and clinical anxiety and can resolve activity over short time intervals like those for some moods and emotions. These results could be incorporated into an objective instrumented test that measures EEG and CRs of autonomic activity and psychological ratings related to conditioned fear, some of which are subliminal. As in the case of instrumented tests of vigilance, these results could be useful for the direct, objective measurement of multiple aspects of the risk, diagnosis, and monitoring of therapies for anxiety disorders and anxious personalities.

Randomized Placebo-/Sham-Controlled Trials of Spinal Cord Stimulation: A Systematic Review and Methodological Appraisal.

OBJECTIVES: The recent availability of paraesthesia/sensation free spinal cord stimulation (SCS) modalities allow the design of clinical trials of SCS using placebo/sham controls and blinding of patients, clinicians, and researchers. The aims of this study were to: 1) systematically review the current evidence base of randomized controlled trials (RCTs) of SCS placebo/sham trials and 2) to undertake a methodological critique of their methods. Based on this critique, we developed a checklist for the design and reporting of future RCTs of SCS. MATERIALS AND METHODS: Electronic data bases were searched from inception until January 2019 for RCTs of SCS using a placebo/sham control. RCTs with only an active comparator arm were excluded. The results are presented as a narrative synthesis. RESULTS: Searches identified 12 eligible RCTs. SCS modalities included paraesthesia stimulation, subthreshold, burst, and high-frequency SCS and were mainly conducted in patients with failed back surgery syndrome, complex regional pain syndrome, and refractory angina. The quality and transparency of reporting of the methods of placebo stimulation, blinding of patients, clinicians, and researchers varied markedly across studies. CONCLUSIONS: To date the methods of placebo/sham control and blinding in RCTs have been poorly reported, leading to concerns about the validity and replicability of the findings. Important aspects that need to be clearly reported in the design of placebo-/sham-controlled RCTs of SCS include the transparent reporting of stimulation programming parameters, patient position during perception threshold measurement, management of the patient handheld programmer, frequency of recharging, and assessment of the fidelity of blinding.

European Headache Federation recommendations for placebo and nocebo terminology.

BACKGROUND AND AIM: Despite recent publications, practitioners remain unfamiliar with the current terminology related to the placebo and nocebo phenomena observed in clinical trials and practice, nor with the factors that modulate them. To cover the gap, the European Headache Federation appointed a panel of experts to clarify the terms associated with the use of placebo in clinical trials. METHODS: The working group identified relevant questions and agreed upon recommendations. Because no data were required to answer the questions, the GRADE approach was not applicable, and thus only expert opinion was provided according to an amended Delphi method. The initial 12 topics for discussion were revised in the opinion of the majority of the panelists, and after a total of 6 rounds of negotiations, the final agreement is presented. RESULTS/RECOMMENDATIONS: Two primary and mechanism-based recommendations are provided for the results of clinical trials: [1] to distinguish the placebo or nocebo response from the placebo or nocebo effect; and [2] for any favorable outcome observed after placebo administration, the term "placebo response" should be used, and for any unfavorable outcome recorded after placebo administration, the term "nocebo response" should be used (12 out of 17 panelists agreed, 70.6% agreement). The placebo or nocebo responses are attributed to a set of factors including those that are related to the medical condition (e.g. natural history, random comorbidities, etc.), along with idiosyncratic ones, in which the placebo or nocebo effects are attributed to idiosyncratic, or nonspecific mechanisms, exclusively (e.g. expectation, conditioning, observational learning etc.). To help investigators and practitioners, the panel summarized a list of environmental factors and idiosyncratic dynamics modulating placebo and nocebo effects. Some of them are modifiable, and investigators or physicians need to know about them in order to modify these factors appropriately to improve treatment. One secondary recommendation addresses the use of the terms "placebo" and "nocebo" ("placebos" and "nocebos" in plural), which refer to the triggers of the placebo/nocebo effects or responses, respectively, and which are inert agents or interventions that should not be confused with the placebo/nocebo responses or effects themselves (all panelists agreed, 100% agreement). CONCLUSION: The working group recommends distinguishing the term response from effect to describe health changes from before to after placebo application and to distinguish the terms placebo(s) or nocebo(s) from the health consequences that they cause (placebo/nocebo responses or effects).

Are Invasive Procedures Effective for Chronic Pain? A Systematic Review.

OBJECTIVE: To assess the evidence for the safety and efficacy of invasive procedures for reducing chronic pain and improving function and health-related quality of life compared with sham (placebo) procedures. DESIGN: Systematic review with meta-analysis. METHODS: Studies were identified by searching multiple electronic databases, examining reference lists, and communicating with experts. Randomized controlled trials comparing invasive procedures with identical but otherwise sham procedures for chronic pain conditions were selected. Three authors independently extracted and described study characteristics and assessed Cochrane risk of bias. Two subsets of data on back and knee pain, respectively, were pooled using random-effects meta-analysis. Overall quality of the literature was assessed through Grading of Recommendations, Assessment, Development, and Evaluation. RESULTS: Twenty-five trials (2,000 participants) were included in the review assessing the effect of invasive procedures over sham. Conditions included low back (N = 7 trials), arthritis (4), angina (4), abdominal pain (3), endometriosis (3), biliary colic (2), and migraine (2). Thirteen trials (52%) reported an adequate concealment of allocation. Fourteen studies (56%) reported on adverse events. Of these, the risk of any adverse event was significantly higher for invasive procedures (12%) than sham procedures (4%; risk difference = 0.05, 95% confidence interval [CI] = 0.01 to 0.09, P = 0.01, I2 = 65%). In the two meta-analysis subsets, the standardized mean difference for reduction of low back pain in seven studies (N = 445) was 0.18 (95% CI = -0.14 to 0.51, P = 0.26, I2 = 62%), and for knee pain in three studies (N = 496) it was 0.04 (95% CI = -0.11 to 0.19, P = 0.63, I2 = 36%). The relative contribution of within-group improvement in sham treatments accounted for 87% of the effect compared with active treatment across all conditions. CONCLUSIONS: There is little evidence for the specific efficacy beyond sham for invasive procedures in chronic pain. A moderate amount of evidence does not support the use of invasive procedures as compared with sham procedures for patients with chronic back or knee pain. Given their high cost and safety concerns, more rigorous studies are required before invasive procedures are routinely used for patients with chronic pain.