Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome

Transcriptomic Profiles Associated with Experimental Placebo Effects in Chronic Pain

Gene expression networks associated with placebo effects are understudied; in this study, we identified transcriptomic profiles associated with placebo responsivity. Participants suffering from chronic pain underwent a verbal suggestion and conditioning paradigm with individually tailored thermal painful stimulations to elicit conditioned placebo effects. Participants reported pain intensity on a visual analog scale (VAS) anchored from zero = no pain to 100 = maximum imaginable pain. RNA was extracted from venous blood and RNA sequencing and validation tests were performed to identify differentially expressed genes (DEGs) associated with placebo effects, controlling for sex and level of pain. Unbiased enrichment analyses were performed to identify biological processes associated with placebo effects. Of the 10,700 protein-coding genes that passed quality control filters, 667 were found to be associated with placebo effects (FDR <0.05). Most genes (97%) upregulated were associated with larger placebo effects. The 17 top transcriptome-wide significant genes were further validated via RT-qPCR in an independent cohort of chronic pain participants. Six of them (CCDC85B, FBXL15, HAGH, PI3, SELENOM, and TNFRSF4) showed positive and significant (P < 0.05) correlation with placebo effects in the cohort. The overall DEGs were highly enriched in regulation of expression of SLITs and ROBOs (R-HSA-9010553, FDR = 1.26e-33), metabolism of RNA (R-HSA-8953854, FDR = 1.34e-30), Huntington's disease (hsa05016, FDR = 9.84e-31), and ribosome biogenesis (GO:0042254, FDR = 2.67e-15); alternations in these pathways might jeopardize the proneness to elicit placebo effects. Future studies are needed to replicate this finding and better understand the unique molecular dynamics of people who are more or less affected by pain and placebo.

Inpatient's, therapist's and staff's expectations regarding treatment and their effects on placebo response in the psychiatric ward - results from an add-on oxytocin RCT

OBJECTIVES

Patient's and therapist's expectations are considered an important factor influencing placebo response in experimental and therapeutic settings. Nevertheless, the placebo effects of common neurological facilitators that promote treatment efficacy have not been explored. In the present study we examined the estimations of patients, therapists, and staff members, regarding their treatment type and assessed their influence on the facilitating effects of oxytocin.

METHODS

Patients (N = 87) were randomized and double-blindly allocated to receive either oxytocin or placebo, twice daily for a period of four weeks, as part of a larger randomized, double-blind, placebo-controlled trial. Patient's, therapist's and staff's expectations were assessed based on their estimation of treatment type (agent or placebo). Multilevel modeling and univariate and multivariate regression analysis were performed to assess the effects of patient's, therapist's, and staff's estimations on treatment outcome beyond the effects of treatment type.

RESULTS

Staff's, therapist's, and patient's estimations were significantly associated with treatment outcomes. Nevertheless, only therapist's and patient's estimations significantly predicted improvement beyond actual administration, with therapist's and patient's estimations associated with improvement in trait anxiety (STAI-T, B=-1.80, p < .05, and B=-2.02, p < .05, respectively); therapist's estimations were associated with improvement in general distress (OQ-45, B=-3.71, p < .05), and patient's estimations were associated with symptom relief (HSCL-11, B=-0.13, p < .05). Overall, patient's estimations had a higher relative contribution to treatment success, with standardized coefficients across scales ranging from - 0.06 to -0.26.

CONCLUSIONS

The neurobiological factors that promote treatment success are also influenced by patient's and therapist's expectations. Future studies should consider these effects when examining their impact in inpatient settings.

The impact of an illness perception conversation on open-label placebo response in knee osteoarthritis: A randomised controlled trial

OBJECTIVE

To compare the effect of an illness perception conversation (IPC), relative to a research participation conversation (RPC), on 2-week changes in knee pain in patients with knee osteoarthritis.

METHOD

This was a randomised single-blind trial. Patients were randomised to two matched conversations. An IP conversation concerning the participant's knee pain-related illness perception (IP) or an RPC concerning the participant's motivation for participating in research. Both conversations were followed by an open-label intraarticular saline injection in the most symptomatic knee. The primary outcome was change in knee pain from baseline to 2 weeks follow-up on a 100 mm visual analogue scale (VAS). Key secondary outcomes included the Knee injury and Osteoarthritis Outcome Score (KOOS) subscales: Activities of daily living (ADL) and Quality of life (QoL). Main analyses were based on the intention-to-treat population using repeated measures mixed effects linear models.

RESULTS

103 patients were randomised to the IPC group (n = 52) and the RPC group (n = 51). VAS knee pain scores changed statistically significantly from baseline to end of treatment in both groups, -13.7 (standard error [SE]: 3.2) in the IPC group and -13.0 (SE: 3.1) in the RPC group with an adjusted between-group difference of -0.7 (95% CI: -8.3 to 6.9; P = 0.85). Likewise, no group differences were seen in KOOS ADL and KOOS QoL.

CONCLUSION

A conversation concerning knee pain-related IP did not augment the pain-relieving effect of an open-label placebo injection when compared to a similar control conversation concerning motivations for participating in research.

TRIAL REGISTRATION

NCT05225480.

Placebo treatment affects brain systems related to affective and cognitive processes, but not nociceptive pain

Drug treatments for pain often do not outperform placebo, and a better understanding of placebo mechanisms is needed to improve treatment development and clinical practice. In a large-scale fMRI study (N = 392) with pre-registered analyses, we tested whether placebo analgesic treatment modulates nociceptive processes, and whether its effects generalize from conditioned to unconditioned pain modalities. Placebo treatment caused robust analgesia in conditioned thermal pain that generalized to unconditioned mechanical pain. However, placebo did not decrease pain-related fMRI activity in brain measures linked to nociceptive pain, including the Neurologic Pain Signature (NPS) and spinothalamic pathway regions, with strong support for null effects in Bayes Factor analyses. In addition, surprisingly, placebo increased activity in some spinothalamic regions for unconditioned mechanical pain. In contrast, placebo reduced activity in a neuromarker associated with higher-level contributions to pain, the Stimulus Intensity Independent Pain Signature (SIIPS), and affected activity in brain regions related to motivation and value, in both pain modalities. Individual differences in behavioral analgesia were correlated with neural changes in both modalities. Our results indicate that cognitive and affective processes primarily drive placebo analgesia, and show the potential of neuromarkers for separating treatment influences on nociception from influences on evaluative processes.

The Role of Attention in Placebo and Nocebo Effects

BACKGROUND

Although some existing models propose that attention may be crucially implicated in placebo/nocebo effects, empirical research on this aspect remains limited and scattered.

PURPOSE

This systematic review aims to provide an inclusive overview of studies that have either directly manipulated or assessed attention within the context of placebo and nocebo procedures so to gain a synthetized picture of the role of this variable in placebo/nocebo effects. Importantly, only studies in which attention represented a mechanism or mediator of the placebo/nocebo response, and not a primary outcome, were included.

METHODS

A systematic search was conducted across multiple databases, including PubMed, Scopus, PsycINFO, Web of Science, and Embase, to identify peer-reviewed studies. These studies were subjected to methodological evaluation and eligibility criteria for inclusion.

RESULTS

We identified and classified 12 studies into three categories based on their focus: (i) those that directly assessed attention, (ii) those that directly manipulated participants' attention, and (iii) those that combined both a direct manipulation and assessment of attention. In all selected studies attention acted as a mechanism or mediator of the placebo/nocebo response, and was not considered a primary outcome of the placebo/nocebo manipulation.

CONCLUSIONS

The synthesis of the included studies reveals that the role of attention in placebo and nocebo effects is still a topic of debate, marked by variations in how attention is conceptualized and measured. Results suggest that attention has significant clinical implications, particularly in optimizing therapeutic efficacy by directing patients' focus toward signs of healing and away from indicators of illness or distress. To advance our understanding, future research should explore these attentional mechanisms, in conjunction with neurophysiological correlates.

Patient Expectations and Therapeutic Alliance Affect Pain Reduction Following Lidocaine Infusion in an Interdisciplinary Chronic Pain Clinic

Pain experience is affected by both ascending nociceptive signals and descending modulation. Expectations can affect pain experience and augment treatment-induced analgesia through descending inhibitory modulation of pain. This open-label, prospective cohort study examined the association between participant expectation ratings and pain reduction in adult participants with chronic pain receiving an intravenous lidocaine infusion. We aimed to explore whether: 1) participants' expectations of treatment efficacy were associated with pain reduction over 8 weeks after infusion; and 2) participants' therapeutic alliance was associated with expectations and/or pain reduction. We recruited 70 participants with chronic pain scheduled for lidocaine infusion. Study measures included pain intensity (pre-treatment, post-treatment, and daily for 8 weeks), treatment expectations (EXPECT), and therapeutic alliance (Trust in Physician and Working Alliance Inventory-Short Revised). Baseline treatment expectations were significantly correlated with pain reduction (r = .42, P < .01). Therapeutic alliance was significantly correlated with expectations (r = .27, P < .05) and pain reduction (r = .38, P < .01). This study quantifies the contribution of: 1) treatment expectations; and 2) therapeutic alliance to the magnitude of lidocaine-induced pain reduction. Results generate the hypothesis that focused efforts to augment treatment expectations and therapeutic alliance could serve to improve pain treatment outcomes. PERSPECTIVE: This study evaluates the relationship between pain reduction and ratings of: 1) treatment expectations; and 2) therapeutic alliance following an intravenous lidocaine infusion. Results generate the hypothesis that focused efforts to augment treatment expectations and therapeutic alliance could serve to improve pain treatment outcomes.

Therapist's warmth and competence increased positive outcome expectations and alliance in an analogue experiment

Objective: The quality of the therapeutic alliance, treatment motivation, outcome expectations (OE), and specific health behaviour predicts psychotherapy success. Therapists should be able to improve these factors to optimize outcomes. This study investigated the therapist's interpersonal behaviour to optimize alliance, motivation, OE, and health behaviour. Method: A stressed study sample (N = 465) completed an online analogue experiment. We gave participants positive information about psychotherapy effectiveness and varied the therapist's interpersonal behaviour along the dimensions of warmth and competence.Results: High (vs. low) competence and high (vs. low) warmth increased alliance, OE, and help-seeking scores, while high (vs. low) competence increased motivation to do psychotherapy. We found no effects on health behaviour.Conclusion: In contrast to previous correlational analyses, our experimental study supports the causal role of the therapist's warmth and competence and its impact on alliance, motivation, and OE. We discuss approaches for future studies and clinical implications.

Contextual Factors-Enriched Standard Care on mechanical neck pain (ContextualizAR trial): Protocol for a randomised controlled trial

BACKGROUND

Understanding the influence of contextual factors (CFs) on interventions for mechanical neck pain (MNP) is essential for evidence-based practice in physical therapy. However, the specific effects and synergies of combining different CFs remain unclear.

OBJECTIVE

The primary purpose of this study will be to determine if a CFs-Enriched Standard Care (SC) approach is an effective treatment for MNP in terms of reducing pain and improving function.

METHODS

This will be an assessor-blinded, 2-group (1:1) randomised clinical trial (RCT) aiming to enrol 94 participants with neck pain persisting for more than 4 weeks. Both groups will undergo 4 weeks of SC twice weekly, following established clinical practice guidelines. In the intervention group, CFs will be enhanced, encompassing the physical, psychological, and social elements inherent in the clinical encounter, based on existing evidence. The primary outcomes will encompass changes in pain and disability after 4 weeks of treatment, with a follow-up reassessment at week 12 post-treatment. Secondary outcomes will include changes in Active Range of Motion, Global Rating of Change, and Satisfaction with treatment. The change between groups after treatment and at the 12-week follow-up will be reported for all outcomes, considering the difference from scores recorded at baseline.

RESULTS

We hypothesise that a 4-week CFs-Enriched SC approach will be superior to SC alone in terms of patient-reported disability and pain, with measurements conducted using the Northwick Park Neck Pain Questionnaire and the Numeric Pain Rating Scale, respectively.

CONCLUSION

This RCT rigorously assesses the effect of purposeful manipulation of CFs during MNP treatment. By elucidating the role of these factors, our findings have the potential to significantly refine clinical practice in managing MNP, thereby enhancing patient care, and advancing the fields of physical therapy and rehabilitation.

Working with patients' treatment expectations - what we can learn from homeopathy

The usual homeopathic remedy, "globules," does not contain any pharmacologically active ingredient. However, many patients and practitioners report beneficial effects of homeopathic treatment on various health outcomes. Experimental and clinical research of the last two decades analyzing the underlying mechanisms of the placebo effect could explain this phenomenon, with patients' treatment expectations as the predominant mechanism. Treatment expectations can be optimized through various factors, such as prior information, communication, and treatment context. This narrative review analyses how homeopathy successfully utilizes these factors. Subsequently, it is discussed what evidence-based medicine could learn from homeopathic practice to optimize treatment expectations (e.g., using an empathic, patient-centered communication style, deliberately selecting objects in practice rooms, or using clear treatment rituals and salient contextual stimuli) and thereby treatment effectiveness. Homeopathic remedy does not work beyond the placebo effect but is recommended or prescribed as an active treatment by those who believe in it. Thus, practitioners need to understand the manner in which homeopathy (as an example of inert treatment) works and are advised to reintegrate its underlying effective placebo mechanisms into evidence-based medicine. This promises to increase treatment efficacy, tolerability, satisfaction, and compliance with evidence-based treatments, and addresses the desires patients are trying to satisfy in homeopathy in an ethical, fully informed way that is grounded in evidence-based medicine.

Neuropsychological mechanisms of observational learning in human placebo effects

Scientific evidence indicates that placebo effects are psychoneurobiological events involving the contribution of distinct central nervous systems and peripheral physiological mechanisms that influence pain perception and other symptoms. Placebo effects can occur without formal conditioning and direct prior experience because crucial information can be acquired through observational learning. Observation of benefits in another person results in placebo effects of a magnitude like those induced by directly experiencing an analgesic benefit. Understanding the psychological mechanisms of observationally induced placebo effects is a complex and multifaceted endeavor. While previous reviews have highlighted various frameworks and models to understand these phenomena, the underlying biological mechanisms have been overlooked. We summarize critically current understanding of its behavioral and neural mechanisms. Understanding the neural mechanisms of hypoalgesia driven by observation can serve as a foundation for future development of novel theoretical and methodological approaches and ultimately, applications.

"Dare to feel full"-A group treatment method for sustainable weight reduction in overweight and obese adults: A randomized controlled trial with 5-years follow-up

OBJECTIVES

To assess the long-term effects on weight reduction and health of a group-based behavioral weight intervention over six months focusing eating for fulfillment as compared to a control regime with brief intervention.

METHOD

Overweight or obese adults (n = 176, 80% female, mean BMI 33.8 ± 4.7 kg/m2, mean age 55.2 ±10.1 years) were randomized to a group treatment or control receiving a brief intervention. Ninety-three participants (53% of original sample) completed the 5-year follow-up. Anthropometrics, blood pressure and biochemical measurements, self-rated lifestyle habits, quality of life and medication were obtained at baseline, at the end of the 6-month intervention, and once a year for five years following randomization.

RESULTS

A per-protocol analysis, performed due to a high drop-out rate, found that weight reduction was small and similar in the two groups after five years. Reduction of waist/hip ratio, total-cholesterol and triglycerides were somewhat larger in the control group than in the treatment group. No changes regarding blood pressure, quality of life or medication use between the treatment and control groups were found.

CONCLUSIONS

No effect on weight reduction of the group intervention was found as compared to brief intervention but both groups achieved small weight loss over time. Findings indicate that any intervention or merely regular follow-ups might be promotive for weight maintenance in middle age.

Change in pain expectations but no open-label placebo analgesia: An experimental study using the heat pain paradigm

BACKGROUND

Open-label placebos (OLP) prescribed without deception and with a convincing rationale have been shown to evoke powerful treatment effects. Patients' treatment expectations seem to influence the magnitude of the effect.

OBJECTIVE

We examined if two different OLP rationales increased pain tolerance and reduced pain intensity and unpleasantness in a standardized heat pain experiment.

METHODS

Participants (N = 71) who self-reported reoccurring pain for at least the last 3 months were randomly assigned to one of three groups. We compared a personal-emotional and a scientific-matter-of-fact rationale with a control group (CG) that received the same placebo without any rationale. The rationale suggested a desensitizing effect on pain perception and improved pain coping of the placebo, whereas in the CG it was introduced as an ointment for measurement. The primary outcomes were pre-post changes in pain tolerance, expected and experienced pain intensity and unpleasantness.

RESULTS

Participants showed a decrease in expected pain intensity, but not expected pain unpleasantness for both rationales. There were no differences in pain tolerance and experienced pain intensity and unpleasantness.

CONCLUSIONS

Our study suggests that evoking positive treatment expectations is not sufficient to elicit an OLP response. Possibly, the magnitude of expectations change in this study was not powerful enough to evoke an OLP effect. Additionally, it is possible that OLP effects in pain are unrelated to positive treatment expectations. The failure of OLP in our study is in contrast to a number of previous studies examining the effects of OLP in experimental and clinical pain.

SIGNIFICANCE

This study provides evidence that positive treatment expectations are not sufficient to evoke an open-label placebo effect in a standardized heat pain experiment. We showed that two different rationales improved participants treatment expectations, but failed to evoke a placebo effect in comparison to a control group that received the same placebo, labelled as an ointment to improve measurement quality.

Practitioner warmth and empathy attenuates the nocebo effect and enhances the placebo effect

Augmented patient-practitioner interactions that enhance therapeutic alliance can increase the placebo effect to sham treatment. Little is known, however, about the effect of these interactions on maladaptive health outcomes (i.e., the nocebo effect). Healthy participants (N = 84) were randomised to a 3-day course of Oxytocin nasal drops (actually, sham treatment) in conjunction with a high-warmth interaction (Oxy-HW: N = 28), a low-warmth interaction (Oxy-LW: N = 28) or to a no treatment control group (NT: N = 28). All participants were informed that the Oxytocin treatment could increase psychological well-being but was associated with several potential side effects. Treatment-related side effects, unwarned symptoms, and psychological well-being were measured at baseline and all post-treatment days. Side effect reporting was increased in the Oxy-LW condition compared to the other groups across all days. Conversely, increased psychological well-being was observed in the Oxy-HW condition, relative to the other conditions, but only on Day 1. Among those receiving treatment, positive and negative expectations, and treatment-related worry, did not vary by interaction-style, while psychological well-being and side effect reporting were inversely associated at the level of the individual. Results have important implications for practice, suggesting poorer quality interactions may not only reduce beneficial health outcomes but also exacerbate those that are maladaptive.

Acupuncture for Chronic Radiation-Induced Xerostomia in Head and Neck Cancer: A Multicenter Randomized Clinical Trial

Importance

Patients with head and neck cancer who undergo radiotherapy can develop chronic radiation-induced xerostomia. Prior acupuncture studies were single center and rated as having high risk of bias, making it difficult to know the benefits of acupuncture for treating radiation-induced xerostomia.

Objective

To compare true acupuncture (TA), sham acupuncture (SA), and standard oral hygiene (SOH) for treating radiation-induced xerostomia.

Design, Setting, and Participants

A randomized, blinded, 3-arm, placebo-controlled trial was conducted between July 29, 2013, and June 9, 2021. Data analysis was performed from March 9, 2022, through May 17, 2023. Patients reporting grade 2 or 3 radiation-induced xerostomia 12 months or more postradiotherapy for head and neck cancer were recruited from community-based cancer centers across the US that were part of the Wake Forest National Cancer Institute Community Oncology Research Program Research Base. Participants had received bilateral radiotherapy with no history of xerostomia.

Interventions

Participants received SOH and were randomized to TA, SA, or SOH only. Participants in the TA and SA cohorts were treated 2 times per week for 4 weeks. Those experiencing a minor response received another 4 weeks of treatment.

Main Outcomes and Measures

Patient-reported outcomes for xerostomia (Xerostomia Questionnaire, primary outcome) and quality of life (Functional Assessment of Cancer Therapy-General) were collected at baseline, 4 (primary time point), 8, 12, and 26 weeks. All analyses were intention to treat.

Results

A total of 258 patients (201 men [77.9%]; mean [SD] age, 65.0 [9.16] years), participated from 33 sites across 13 states. Overall, 86 patients were assigned to each study arm. Mean (SD) years from diagnosis was 4.21 (3.74) years, 67.1% (n = 173) had stage IV disease. At week 4, Xerostomia Questionnaire scores revealed significant between-group differences, with lower Xerostomia Questionnaire scores with TA vs SOH (TA: 50.6; SOH: 57.3; difference, -6.67; 95% CI, -11.08 to -2.27; P = .003), and differences between TA and SA (TA: 50.6; SA: 55.0; difference, -4.41; 95% CI, -8.62 to -0.19; P = .04) yet did not reach statistical significance after adjustment for multiple comparisons. There was no significant difference between SA and SOH. Group differences in Functional Assessment of Cancer Therapy-General scores revealed statistically significant group differences at week 4, with higher scores with TA vs SOH (TA: 101.6; SOH: 97.7; difference, 3.91; 95% CI, 1.43-6.38; P = .002) and at week 12, with higher scores with TA vs SA (TA: 102.1; SA: 98.4; difference, 3.64; 95% CI, 1.10-6.18; P = .005) and TA vs SOH (TA: 102.1; SOH: 97.4; difference, 4.61; 95% CI, 1.99-7.23; P = .001).

Conclusions and Relevance

The findings of this trial suggest that TA was more effective in treating chronic radiation-induced xerostomia 1 or more years after the end of radiotherapy than SA or SOH.

Trial Registration

ClinicalTrials.gov Identifier: NCT02589938.

Matched vs Nonmatched Placebos in a Randomized Trial of COVID-19 Treatments

Importance

Matched placebo interventions are complex and resource intensive. Recent evidence suggests matched placebos may not always be necessary. Previous studies have predominantly evaluated potential bias of nonmatched placebos (ie, differing on dose, frequency of administration, or formulation) in pain and mental health, but to date no systematic examination has been conducted in infectious disease.

Objective

To test for differences between nonmatched and matched placebo arms with respect to clinical outcome measures across multiple therapeutics for COVID-19.

Design, Setting, and Participants

In a comparative effectiveness research study, a post hoc analysis was conducted of data on individual patients enrolled in a large, multiarm, platform randomized clinical trial in symptomatic adult outpatients with COVID-19 between January 15, 2021, to September 28, 2023, in which the outcomes of both matched and nonmatched placebo groups were reported. Bayesian and frequentist covariate-adjusted techniques were compared with 7 intervention-placebo pairs.

Exposures

Seven matched and nonmatched placebo pairs (for a total of 7 comparisons) were evaluated throughout the primary platform trial. Comparisons were made between treatment and its associated matched (concurrent) placebo, as well as with nonmatched placebo (alone and in combination) assessed at a similar time point.

Main Outcomes and Measures

Outcomes assessed included hospitalizations, EuroQol 5-Dimension 5-level scores, and PROMIS Global-10 scores.

Results

A total of 7 intervention-control pairs (N = 2684) were assessed, including 1620 (60.4%) women, with mean (SD) age, 47 (15.2) years; the most common comorbidities were obesity (41.9%) and hypertension (37.9%). In a meta-analysis with decoupled SEs, accounting for overlapping placebo patients, the overall odds ratio (OR) of nonmatched compared with matched placebo was 1.01 (95% credible interval, 0.77-1.32), with posterior probability of equivalence, defined as 0.8 ≤ OR ≤ 1.2 (a deviation from perfect equivalence ie, OR = 1, by no more than 0.2) of 85.4%, implying no significant difference. Unadjusted analysis of the event rate difference between all nonmatched and matched placebo groups did not identify any notable differences across all 7 treatment-placebo combinations assessed. Similar analysis that was conducted for patient-reported quality of life outcomes did not yield statistically significant differences.

Conclusions and Relevance

In this post hoc study of a randomized clinical platform trial, pooling matched and nonmatched placebo patient data did not lead to inconsistencies in treatment effect estimation for any of the investigational drugs. These findings may have significant implications for future platform trials, as the use of nonmatched placebo may improve statistical power, or reduce barriers to placebo implementation.

Effects on temporomandibular disorder in the treatment of tension-type headache with acupuncture and therapeutic exercises. A secondary analysis from a randomized controlled trial

OBJECTIVES

To examine the effects of acupuncture and therapeutic exercise alone and in combination on temporomandibular joint symptoms in tension-type headache and to evaluate the potential interaction of existing temporomandibular dysfunction on the success of headache treatment.

DESIGN

Pre-planned secondary analysis of a randomized controlled, non-blinded trial.

SETTING

Outpatient clinic of a German university hospital.

SUBJECTS

Ninety-six Participants with frequent episodic or chronic tension-type headache were randomized to one of four treatment groups.

INTERVENTIONS

Six weeks of acupuncture or therapeutic exercise either as monotherapies or in combination, or usual care. Follow-up at 3 and 6 months.

MAIN MEASURES

Subjective temporomandibular dysfunction symptoms were measured using the Functional Questionnaire Masticatory Organ, and the influence of this sum score and objective initial dental examination on the efficacy of headache treatment interventions was analyzed.

RESULTS

Temporomandibular dysfunction score improved in all intervention groups at 3-month follow-up (usual care: 0.05 [SD 1.435]; acupuncture: -5 [SD 1.436]; therapeutic exercise: -4 [SD 1.798]; combination: -3 [SD 1.504]; P = 0.03). After 6 months, only acupuncture (-6 [SD 1.736]) showed a significant improvement compared to the usual care group (P < 0.01). Subjective temporomandibular dysfunction symptoms had no overall influence on headache treatment.

CONCLUSIONS

Only acupuncture had long-lasting positive effects on the symptoms of temporomandibular dysfunction. Significant dental findings seem to inhibit the efficacy of acupuncture for tension-type headache.

The Effect of Singular Nonverbal Behaviours of Experimenters on Pain Reports

Introduction

Studies suggest facial expressions of caregivers may be important in placebo effects; however, this has not been systematically tested. This experiment investigated the effects of caregivers' singular positive nonverbal behaviours (NBs) on pain reports.

Methods

Fifty-one males and 53 females (total of 104) participants were randomized to four groups that were displayed positive facial expressions, tone of voice, body movement, or neutral NBs of videotaped experimenters. Subjective reports of pain, stress, arousal, and cardiac activity were obtained in a pre-test, a conditioning phase, and at a post-test. Four minutes of heat pain was induced in each test, and a placebo cream was administered before the conditioning and post-test in all groups.

Results

There were no differences between the NB groups in the reduced pain. Males had larger reduction in pain in the post-test, and females had lower arousal than the opposite sex. During the conditioning, females had larger reduction in pain ie, unconditioned pain response (UPR). In females, the UPR predicted the reinforced expectation ie, increase in expectations from conditioning to post-test, and fear of minor pain negatively predicted both the UPR and reinforced expectation.

Discussion

Singular NBs of caregiver were weak to enhance placebo effects. Females had lower pain during conditioning, and the UPR amplitude in females was associated with positive expectations. Moreover, for females, fear of minor pain weakened the UPR and expectations of cream.

Conclusion

No NB of caregivers is more effective in reducing pain. Caregivers' NBs are less effective when displayed individually. Males and females may be different in underlying mechanisms of placebo effects.

The effect of nocebo explanation and empathy on side-effect expectations of medication use following a fictional GP consultation

The simple act of informing patients about side-effects increases the likelihood they will experience them (i.e. the nocebo effect). Explaining this psychological phenomenon could help to reduce side-effect experience, however, it is yet to be explored if this can be applied to clinical settings where new medication is prescribed. In addition, the degree to which a health-care provider empathetically communicates this to patients may have an impact. To investigate this, we carried out 2 × 2 factorial trial to assess the effect of nocebo explanation and empathy (plus their interaction) on side-effect expectations following a fictional GP consultation prescribing a new medication. Overall, 208 participants were randomised to watch one of the four fictive GP consultations and play the role of the patient. In all videos, participants received information about the reason for the consultation, the recommendation of a new fictive medicine, how to take it, benefits and side-effects. The videos differed in whether the GP provided an explanation of the nocebo effect (yes/no) and whether they communicated in an empathetic style (yes/no). After watching the video, participants were asked about their side-effect expectations and rated the quality of the GP's communication. Two-way ANOVAs revealed no main effect of nocebo explanation on expectation of side-effects warned or not warned about in the consultation. However, there was a main effect of empathy, with participants watching the empathetic consultations having significantly lower expectations of non-warned-about side-effects. There was no significant interaction. Findings suggest that explaining the nocebo effect and GP empathy did little to allay expectations of side-effects that were specifically mentioned in the consultation. However, GP empathy had an effect by helping to reduce additional side-effect expectations participants still had. Future work should extend these findings to real GP consultations where the full dimensions of empathy can be explored.

A double-blind, randomized, placebo-controlled study assessing the impact of probiotic supplementation on the symptoms of irritable bowel syndrome in females

BACKGROUND

A previous exploratory study demonstrated the ability of the Lab4 probiotic to alleviate the symptoms of IBS, and post hoc data analysis indicated greatest improvements in the female subgroup. The aim of this study is to confirm the impact of this multistrain probiotic on IBS symptom severity in females.

METHODS

An 8-week, single-center, randomized, double-blinded, placebo-controlled, superiority study in 70 females with Rome IV-diagnosed irritable bowel syndrome (IBS) receiving the Lab4 probiotic (25 billion colony-forming units) daily or a matched placebo. Changes from baseline in the IBS-symptom severity score (IBS-SSS), daily bowel habits, anxiety, depression, IBS-related control, and avoidance behavior, executive function, and the fecal microbiota composition were assessed. The study was prospectively registered: ISRCTN 14866272 (registration date 20/07/22).

KEY RESULTS

At the end of the study, there were significant between-group reductions in IBS-SSS (-85.0, p < 0.0001), anxiety and depression scores (-1.9, p = 0.0002 and -2.4, p < 0.0001, respectively), and the IBS-related control and avoidance behavior score (-7.5, p = 0.0002), all favoring the probiotic group. A higher proportion of the participants in the probiotic group had normal stool form (p = 0.0106) and/or fewer defecations with loose stool form (p = 0.0311). There was little impact on the overall diversity of the fecal microbiota but there were significant differences in Roseburia, Holdemanella, Blautia, Agathobacter, Ruminococcus, Prevotella, Bacteroides, and Anaerostipes between the probiotic and placebo groups at the end of the study.

CONCLUSIONS & INFERENCES

Daily supplementation with this probiotic may represent an option to be considered in the management of IBS.

Association between expectations and clinical outcomes in online v. face-to-face therapy - an individual participant data meta-analysis

BACKGROUND

Online treatments are increasing in number and are currently available for a wide range of clinical problems. To date little is known about the role of treatment expectations and other placebo-like mechanisms in online settings compared to traditional face-to-face treatment. To address this knowledge gap, we analyzed individual participant data from randomized clinical trials that compared online and face-to-face psychological interventions.

METHODS

MEDLINE (Ovid) and PsycINFO (Ovid) were last searched on 2 February 2021. Randomized clinical trials of therapist guided online v. face-to-face psychological interventions for psychiatric or somatic conditions using a randomized controlled design were included. Titles, abstracts, and full texts of studies were independently screened by multiple observers. The Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline was followed. Authors of the matching trials were contacted for individual participant data. Ratings from the Credibility and Expectancy Questionnaire and the primary outcome measure from each trial were used to estimate the association between expectation ratings and treatment outcomes in online v. face-to-face interventions, using a mixed-effects model.

RESULTS

Of 7045 screened studies, 62 full-text articles were retrieved whereof six studies fulfilled the criteria and provided individual participant data (n = 491). Overall, CEQ ratings predicted clinical outcomes (β = 0.27) at end of treatment with no moderating effect of treatment modality (online v. face-to-face).

CONCLUSIONS

Online treatment appears to be equally susceptible to expectancy effects as face-to-face therapy. This furthers our understanding of the importance of placebo-like factors in online treatment and may aid the improvement of healthcare in online settings.

Influence of patient-clinician relationship style on acupuncture outcomes in functional dyspepsia: A multi-site randomized controlled trial in Korea

INTRODUCTION

Research suggests that a warm and empathic "patient-centered" patient-clinician relationship produces better clinical outcomes when compared with a more neutral "disease-centered" relationship. Acupuncturists performed both styles of therapy for patients with functional dyspepsia in Korea.

METHODS

The present randomized controlled trial assigned patients (n = 73) to identical acupuncture treatment with either patient-centered augmented care or disease-centered limited care. The Korean version of the Nepean Dyspepsia Index (NDI-K) was the primary outcome measure. Secondary outcome measures included Consultation And Relational Empathy (CARE) scale.

RESULTS

Both groups showed improvement in NDI-K. Patient-centered augmented acupuncture produced less effective symptom improvement compared to disease-centered limited acupuncture (NDI-K sum score and frequency; P = 0.008 and P = 0.037 respectively). CARE scores were higher for the augmented versus limited group (P = 0.001), supporting the fidelity of the experimentally controlled patient/clinician relationship. There were no significant differences between the groups in any of other secondary outcomes.

CONCLUSION

Patients demonstrated greater improvement following acupuncture conducted with a more neutral, "disease-centered" style of relationship. This result is counter to similar research conducted in Western countries and suggests that cultural factors can significantly shape optimum styles of acupuncture therapy.

PRACTICE IMPLICATIONS

Clinicians should consider cultural differences when applying acupuncture therapy.

Negative expectations (nocebo phenomenon) in clinical interventions: A scoping review

Unpredictable, undesirable, and confusing reactions in the face of psychological or medical interventions make the clinical presentation more complicated and may represent clinically unexplained symptoms and also disturbed the doctor-patients relationship and decrease patients' benefits of treatment. It seems that negative expectations from the treatment (nocebo phenomenon) can explain such reactions. The aim of the current study is a scoping review and investigate different aspects of the nocebo phenomenon (negative expectations) in clinical interventions. This paper follows a scoping review of the existence, importance, and multidimensions of the nocebo phenomenon in medical and psychological interventions. Data sources include literature databases (ProQuest, PubMed, Google Scholar, and Scopus) reviewed from inception dates to 2023, and the terms negative expectations, nocebo effect, placebo effect, negative placebo, and clinical interventions were searched. The review of the available articles showed that negative expectations play an important role in the process and effectiveness of clinical interventions. Negative expectations (here named nocebo effect) can significantly interfere with rapport and treatment processes. Some underlying components of the nocebo effect include negative expectancies, conditioning, social learning, memory, cognitive distortions, meaning, motivation, somatic focus, negative reinforcements, personality, anxiety, and neurophysiological factors such as CCK, dopamine, and cortisol are proposed for development and presence of nocebo phenomenon in clinical practice. Negative expectations with its biopsychosocial aspects play an important and amazing role in disorganizing medical and psychological interventions. Using appropriate methods to reduce nocebo effects in therapeutic interventions may increase treatment compliance and adherence and increase the effectiveness of interventions.

When does the placebo effect have an impact on network meta-analysis results?

The placebo effect is the 'effect of the simulation of treatment that occurs due to a participant's belief or expectation that a treatment is effective'. Although the effect might be of little importance for some conditions, it can have a great role in others, mostly when the evaluated symptoms are subjective. Several characteristics that include informed consent, number of arms in a study, the occurrence of adverse events and quality of blinding may influence response to placebo and possibly bias the results of randomised controlled trials. Such a bias is inherited in systematic reviews of evidence and their quantitative components, pairwise meta-analysis (when two treatments are compared) and network meta-analysis (when more than two treatments are compared). In this paper, we aim to provide red flags as to when a placebo effect is likely to bias pairwise and network meta-analysis treatment effects. The classic paradigm has been that placebo-controlled randomised trials are focused on estimating the treatment effect. However, the magnitude of placebo effect itself may also in some instances be of interest and has also lately received attention. We use component network meta-analysis to estimate placebo effects. We apply these methods to a published network meta-analysis, examining the relative effectiveness of four psychotherapies and four control treatments for depression in 123 studies.

Placebo effect in randomized controlled trials for Meniere's disease: A meta-analysis

PURPOSE

Meniere's Disease is a condition known for its recurrent vertigo, fluctuating sensorineural hearing loss, aural fullness, and tinnitus. Previous studies have demonstrated significant influence of placebo treatments. Our objective was to quantify the magnitude of the placebo effect in randomized controlled trials for Meniere's Disease.

MATERIALS AND METHODS

A systematic review was performed by searching PubMed, SCOPUS, CINAHL, and Cochrane databases from inception through September 27, 2022. Data extraction, quality rating, and risk of bias assessment were performed by two independent reviewers. A meta-analysis of mean differences with 95 % confidence interval, weighted summary proportions, and proportion differences were calculated using random and fixed effects models.

RESULTS

A total of 15 studies (N = 892) were included in the review. Significant improvement was seen in the functional level scores of the pooled placebo groups, with a mean difference of -0.6 points, (95%CI: -1.2 to -0.1). There was no difference in pure tone audiometry, speech discrimination score, or vertigo frequency at 1 and 3 months for the placebo group. Patient-reported vertigo episodes were improved in 52.5 % (95%CI: 39.2 to 65.5) of the placebo group and was significantly less than the pooled experimental group (90.1 %, 95%CI: 39.2 to 65.5, p < 0.001).

CONCLUSIONS

The placebo effect in Meniere's Disease trials is associated with some symptomatic improvement in subjective outcomes, such as patient reported vertigo episodes. However, the clinical significance is questionable across other outcomes measures, especially when analyzing objective data. The extent and strength of the placebo effect continues to be a hurdle in the search for better treatment options.

I and thou in dialogue: Becoming more relational in couple therapy

Couple therapists have the unique and challenging opportunity of helping people find deeper connection in their intimate relationships. These clinicians apply therapeutic models and interventions designed to help couples. However, many of these models are derived from theoretical, scientific, and sociocultural traditions that conceptualize human phenomena as individualistic and reductionistic, and the language in these theories may not match clients' experiences, which include deeply relational phenomena such as love and loss. We review how Western scientific and sociocultural traditions have shaped conceptualization of problems and clinical intervention in couple therapy. In contrast, we provide an alternative, strongly relational framework for couple therapy that draws upon philosophical perspectives asserting that relational, rather than individual, experience is fundamental in human interaction. These ideas provide relational language which can influence how couple therapy is viewed and enacted. Specifically, we discuss how a strongly relational approach changes how therapists understand and intervene with conflict, abuse, love, and deception. This relational framework can help couples in their own goals to become more unified. Implications for the therapeutic relationship, interventions, and scholarship are provided.

Virtual reality hypnosis prior to radiofrequency thermocoagulation for patients with chronic pain: an exploratory clinical trial

Background

The management of chronic pain may involve an array of tools, including radiofrequency thermocoagulation (Rf-Tc) of sensory nerve terminals. Like many other invasive procedures, Rf-Tc can generate anxiety in a lot of patients, either during the expectation of the procedure or in the course of it. Virtual reality hypnosis (VRH) is a promising tool for managing anxiety and pain in several situations, but its anxiolytic property has not been investigated in participants with chronic pain and going through a Rf-Tc procedure.

Objectives

The goal of this study was to evaluate the effectiveness of VRH for reducing self-assessed anxiety in participants with chronic pain, when received in preparation for Rf-Tc.

Materials and methods

This prospective, controlled trial was conducted in the Interdisciplinary Algology Centre of the University Hospital of Liège (Belgium). Participants were assigned to two groups: VRH or control (usual care). Assessment was carried-out at 4 time points: T0 (one week before Rf-Tc); T1 (pre-intervention, on the day of Rf-Tc); T2 (immediately after the VRH intervention outside of the Rf-Tc room); and T3 (right after Rf-Tc). Medical, sociodemographic data, anxiety trait and immersive tendencies were collected at T0. Anxiety state and pain intensity were assessed at each time points. Satisfaction was examined at T3.

Results

Forty-two participants were quasi-randomly assigned to the VRH or control group. No statistically significant interaction group by time was observed regarding all measured variables, including primary endpoint. However, a significant effect of time was found for anxiety and pain when considering both groups together, toward a progressive reduction.

Conclusion

In the context of our study, there appears to be no significant effect of VRH at reducing anxiety in participants with chronic pain undergoing Rf-Tc. Anxiety decreases along the procedure, while pain is attenuated by the local anesthetic infiltration of the Rf site. Our results suggest that the presence of a caregiver throughout the procedure might explain the progressive decrease in anxiety. Future randomized controlled trials are needed to precisely study the effectiveness of the VRH tool, and the possibility of using it as a complementary approach for anxiety during invasive procedures.

"SO FAR AWAY" How Doctors Can Contribute to Making Endometriosis Hell on Earth. A Call for Humanistic Medicine and Empathetic Practice for Genuine Person-Centered Care. A Narrative Review

"SO FAR AWAY" * How Doctors Can Contribute to Making Endometriosis Hell on Earth [* by Knopfler M. In Dire Straits. Brothers in Arms. Vertigo Records, U.K., 1985].

Abstract

The distance physicians may create within the relationship with their patients by not having a humanistic approach to their practice may strongly influence clinical outcomes. The purpose of this paper is to convey the well-known narrative of patient dissatisfaction into pro-action by discussing the aspects of dehumanization, which may occur in the relationship between physicians and women with endometriosis. Eight dimensions of dehumanization are examined and related to everyday scenarios occurring in endometriosis care settings and the possible downstream consequences on patients' clinical outcomes are described. Objectification, which may come across as minimization of pain, may not only increase patients' perception of pain but also lead to undertreatment of unrecognized forms of endometriosis, especially among adolescents. Passivity, that is not favoring shared decision-making nor self-management, may compromise adherence to treatment, reducing patients' trust in physicians and quality of life. The same consequences may result from homogenization, that is giving for granted that all patients have the same access to care. Both isolation, ie not practicing therapeutic empathy, and loss of meaning, ie not supporting patients in the re-definition of their life plans, may affect women's psychological wellbeing and further increase pain perception. Ignoring women's personal journey by not providing clear information on the consequences endometriosis may have on their lives may favor women's self-silencing. Not promoting an un-biased communication and not setting aside scientific polarization are the main features of dislocation, which may jeopardize patient empowerment. Lastly, having a reductionist approach to the body may contribute to chronicization of pain, thus compromising quality of life. This considered, taking time to listen to women with endometriosis and tailoring decisions on the basis of their individual needs should be fostered as a moral duty. Physicians should always keep in mind that they are not only deliverers of treatment; they are a form of treatment themselves.

Histological Remission Placebo Rates in Ulcerative Colitis Trials: A Systematic Review and Meta-analysis

BACKGROUND

High histologic remission rates have been reported with placebos in randomized controlled trials (RCTs) evaluating ulcerative colitis (UC) therapies and have varied based on trial designs. We performed a systematic review and meta-analysis to quantify placebo histological remission rates and identify factors influencing those rates.

METHODS

MEDLINE, EMBASE, and the Cochrane library were searched from inception of the databases until December 2021. We included placebo-controlled RCTs of adult patients with UC treated with aminosalicylates, corticosteroids, immunosuppressives, biologics, and small molecules. We pooled estimates using a random-effects model and performed subgroup analysis and meta-regression to evaluate the effect of different covariates on placebo rates.

RESULTS

Thirty-three studies (30 induction and 3 maintenance) were included. The overall placebo histological remission rate was 15.7% (95% confidence interval, 12.9%-19%) across all 33 studies. High heterogeneity was observed among studies with I2 = 62.10%. The pooled estimate of histological remission was 15.8% in induction studies and 14.5% in maintenance studies. Subgroup analysis revealed statistically significant differences in placebo rates when accounting for background medications, the intervention drug class, and disease severity (P = .041, .025, and .025, respectively). There was no statistical difference between induction vs maintenance studies or between different histological scales (P = .771, and .075, respectively).

CONCLUSIONS

Placebo histological remission rates range from 13% to 19% in UC RCTs, but studies are highly heterogeneous. Factors found to influence placebo rates include presence of background medications, the drug used, and the disease severity. These observations inform future trial designs to minimize placebo rates and reduce heterogeneity.

Brain-computer interface relieves chronic chemotherapy-induced peripheral neuropathy: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) includes negative sensations that remain a major chronic problem for cancer survivors. Previous research demonstrated that neurofeedback (a closed-loop brain-computer interface [BCI]) was effective at treating CIPN versus a waitlist control (WLC). The authors' a priori hypothesis was that BCI would be superior to placebo feedback (placebo control [PLC]) and to WLC in alleviating CIPN and that changes in brain activity would predict symptom report.

METHODS

Randomization to one of three conditions occurred between November 2014 and November 2018. Breast cancer survivors no longer in treatment were assessed at baseline, at the end of 20 treatment sessions, and 1 month later. Auditory and visual rewards were given over 20 sessions based on each patient's ability to modify their own electroencephalographic signals. The Pain Quality Assessment Scale (PQAS) at the end of treatment was the primary outcome, and changes in electroencephalographic signals and 1-month data also were examined.

RESULTS

The BCI and PLC groups reported significant symptom reduction. The BCI group demonstrated larger effect size differences from the WLC group than the PLC group (mean change score: BCI vs. WLC, -2.60 vs. 0.38; 95% confidence interval, -3.67, -1.46 [p = .000; effect size, 1.07]; PLC, -2.26; 95% confidence interval, -3.33, -1.19 [p = .001 vs. WLC; effect size, 0.9]). At 1 month, symptoms continued to improve only for the BCI group. Targeted brain changes at the end of treatment predicted symptoms at 1 month for the BCI group only.

CONCLUSIONS

BCI is a promising treatment for CIPN and may have a longer lasting effect than placebo (nonspecific BCI), which is an important consideration for long-term symptom relief. Although scientifically interesting, the ability to separate real from placebo treatment may not be as important as understanding the placebo effects differently from effects of the intervention.

PLAIN LANGUAGE SUMMARY

Chemotherapy-induced nerve pain (neuropathy) can be disabling for cancer survivors; however, the way symptoms are felt depends on how the brain interprets the signals from nerves in the body. We determined that the perception of neuropathy can be changed by working directly with the brain. Survivors in our trial played 20 sessions of a type of video game that was designed to change the way the brain processed sensation and movement. In this, our second trial, we again observed significant improvement in symptoms that lasted after the treatment was complete.

Current and Emerging Technologies to Address the Placebo Response Challenge in CNS Clinical Trials: Promise, Pitfalls, and Pathways Forward

Excessive placebo response rates have long been a major challenge for central nervous system (CNS) drug discovery. As CNS trials progressively shift toward digitalization, decentralization, and novel remote assessment approaches, questions are emerging about whether innovative technologies can help mitigate the placebo response. This article begins with a conceptual framework for understanding placebo response. We then critically evaluate the potential of a range of innovative technologies and associated research designs that might help mitigate the placebo response and enhance detection of treatment signals. These include technologies developed to directly address placebo response; technology-based approaches focused on recruitment, retention, and data collection with potential relevance to placebo response; and novel remote digital phenotyping technologies. Finally, we describe key scientific and regulatory considerations when evaluating and selecting innovative strategies to mitigate placebo response. While a range of technological innovations shows potential for helping to address the placebo response in CNS trials, much work remains to carefully evaluate their risks and benefits.

Patient engagement as a core element of translating clinical evidence into practice- application of the COM-B model behaviour change model

BACKGROUND

The results of rehabilitation trials are often not fully attained when the intervention is implemented beyond the initial trial. One of the key reasons is that a patients' ability and/or capacity to take part in their own healthcare is not considered in the trial design yet has significant impact on the outcomes during the implementation phase.

BODY OF TEXT

We propose a shift from a therapist-focus to patient-focus in trial design, through addressing patient engagement as a core consideration in trials. We argue that engaging patients in any rehabilitation program is a process of behavioural change. Exercise prescription is used as an example to illustrate how the Behaviour Change Wheel can be applied to analyse barriers and facilitators associated with patients' capabilities, opportunities and motivations in integrating trial interventions into their daily life. We propose a framework to assist in this shift.

CONCLUSION

A core part of implementing rehabilitation interventions at the primary care level requires patient engagement. Related aspects of interventions should be identified and assessed using the COM-B model at the outset of trial design to ensure that the results are realistic, meaningful and transferable, so as to enable real impact.

The Optimal Learning Cocktail for Placebo Analgesia: A Randomized Controlled Trial Comparing Individual and Combined Techniques

This study investigated for the first time the effects of individual and combined application of 3 learning techniques (verbal suggestions, classical conditioning, and observational learning) on placebo analgesia and extinction. Healthy participants (N = 206) were assigned to 8 different groups in which they were taught through either a verbal suggestion, a conditioning paradigm, a video observing someone, or any combination thereof that a placebo device (inactive transcutaneous electric nerve stimulation [TENS]) was capable of alleviating heat pain, whereas one group did not (control). Placebo analgesia was quantified as the within-group difference in experienced pain when the placebo device was (sham) 'activated' or 'inactivated' during equal pain stimuli, and compared between groups. Placebo analgesia was induced in groups with 2 or 3 learning techniques. Significantly stronger placebo analgesia was induced in the combination of all 3 learning techniques as compared to the individual learning techniques or control condition, underlining the additional contribution of 3 combined techniques. Extinction did not differ between groups. Furthermore, pain expectancies, but not state anxiety or trust, mediated placebo analgesia. Our findings emphasize the added value of combining 3 learning techniques to optimally shape expectancies that lead to placebo analgesia, which can be used in experimental and clinical settings. PERSPECTIVE: This unique experimental study compared the individual versus combined effects of 3 important ways of learning (verbal suggestions, classical conditioning, and observational learning) on expectation-based pain relief. The findings indicate that placebo effects occurring in clinical practice could be optimally strengthened if healthcare providers apply these techniques in combination.

Highlights of three metabolites HDL and reduction in blood pressure values after dietary fiber supplementation in overweight and obese normotensive women: a metabolomic study

INTRODUCTION

The prevalence of hypertension and obesity are a worldwide concern.

OBJETIVES

Assess the metabolites profile after intervention with mixed dietary fiber in overweight and obese normotensive women.

METHODS

This is a randomized double blind placebo-controlled study. Through a simple randomization process, two groups were allocated, with eleven women (group 1) receiving 12 g of mixed dietary fiber and thirteen women (group 2) receiving 12 g of placebo (corn starch) for eight weeks. Anthropometric and biochemical tests and lifestyle were analyzed. As for evaluation metabolomics, used a 1H NMR. The data matrix generated 96 samples and 225 variables, which was exported in the ASCII format for the "The Unscrumbler" statistics software (version 9.7, CAMO Process).

RESULTS

After the intervention with mixed dietary fiber, significant differences were observed between the main types of metabolites, referring to the increase in the relative peak areas of in three HDL metabolites 4.94 ppm (0.0086*), HDL 1.28 ppm (0 .0337*), HDL 0.88 ppm (0.0224*) and an α-glucose metabolite 4.90 ppm (0.0106) and the reduction in systolic blood pressure (SBP) (0.0292*) of 7 mmHg in the reference range and in the placebo group there was a reduction in SBP (0.0118*) of 4 mmHg and of a choline metabolite 3.65 ppm (0.0266*), which does not call into question the validity of these results in the literature.

CONCLUSION

The synergism of the functions of these statistically highlighted metabolites contributed to prevention the increase in SBP after fiber intervention in overweight and obese normotensive women.

Probiotics for the management of irritable bowel syndrome: a systematic review and three-level meta-analysis

OBJECTIVE

Previous systematic reviews demonstrated a potentially beneficial effect of probiotics on irritable bowel syndrome (IBS). However, these studies are either affected by the inclusion of insufficient trials or by the problem of dependent data across multiple outcomes, and an overall effect size has not been provided. We aimed to determine the effect of probiotics on IBS through a three-level meta-analysis and clarify potential effect moderators.

METHODS

We searched MEDLINE, Embase, and Web of Science, screening for randomized controlled trials (RCTs) that examine the effect of probiotics on IBS. The primary outcome was the improvement in the severity of global IBS symptoms at the end of treatment. The secondary outcomes were the improvement in abdominal pain and the quality of life. The effect sizes of the probiotics were measured by using the standardized mean difference (SMD) and pooled by a three-level meta-analysis model.

RESULTS

We included 72 RCTs in the analysis. The meta-analysis showed significantly better overall effect of probiotics than placebo on the global IBS symptoms (SMD -0.55, 95% CI -0.76 to -0.34, P <0.001), abdominal pain (SMD -0.89, 95% CI -1.29 to -0.5, P <0.001) and quality of life (SMD 0.99, 95% CI 0.45 to 1.54, P <0.001), respectively. Moderator analysis found that a treatment duration shorter than 4 weeks was associated with a larger effect size in all the outcomes, and Bacillus probiotics had better improvement on the abdominal pain.

CONCLUSIONS

Probiotics had a short-term effect and a medium effect size on the global IBS symptoms. Treatment duration and types of probiotics affected the effect size of probiotics, and shorter durations and Bacillus probiotics were associated with better treatment effects.

REGISTRATION

Open Science Framework.

Is Positive Communication Sufficient to Modulate Procedural Pain and Anxiety in the Emergency Department? A Randomized Controlled Trial

OBJECTIVE

Research suggests that therapeutic communication could enhance patient comfort during medical procedures. Few studies have been conducted in clinical settings, with adequate blinding. Our hypothesis was that a positive message could lead to analgesia and anxiolysis, and that this effect would be enhanced by an empathetic interaction with the nurse performing the procedure, compared with an audio-taped message. This study aimed to modulate the contents and delivery vector of a message regarding peripheral intravenous catheter (PIC) placement in the emergency department (ED).

METHODS

This study was a 2 + 2 randomized controlled trial registered on ClinicalTrials.gov (NCT03502655). A positive versus standard message was delivered through audio tape (double-blind) in the first phase ( N = 131) and through the nurse placing the catheter (single-blind) in the second phase ( N = 120).

RESULTS

By design, low practitioner empathic behavior was observed in the first phase (median, 1 of 5 points). In the second phase, higher empathic behavior was observed in the positive than in the standard message (median, 2 versus 3, p < .001). Contrary to our hypothesis, the intervention did not affect pain or anxiety reports due to PIC placement in either phase (all p values > .2).

CONCLUSIONS

The positive communication intervention did not impact pain or anxiety reports after PIC. There might have been a floor effect, with low PIC pain ratings in a context of moderate pain due to the presenting condition. Hence, such a therapeutic communication intervention might not be sufficient to modulate a mild procedural pain in the ED.

Systematic manipulation of experimenters' non-verbal behaviors for the investigation of pain reports and placebo effects

Objective

Non-verbal behaviors (NBs) of caregivers affect pain reports and placebo effects. However, little experimental research has systematically examined the caregivers' NBs. This study protocol and preparatory study report a systematic manipulation of experimenters' NBs to investigate pain report and placebo effects.

Methods

We propose an experiment in which videotaped experimenters (VEs) conduct a pain stimulation and a placebo treatment study. The VEs express one positively enhanced NB and keep the other NBs neutral. Participants will be randomized to either the positive facial expressions (+FE), tone of voice (+TV), body movement (+BM), or neutral NBs (i.e., neutral condition; NC) of the VEs. As a preparatory study for proof of concept, two groups of NB coders from Norway and the USA separately rated the degree of NBs (eye contact, body postures and movements, and tone of voice), and impressions of dominance and being in charge, positivity, and expressivity from each NB video. The NB videos had construct validity and reliability. The +BM and +FE were rated as more dominant and in charge than the +TV and the NC. The +FE and +BM were rated as the most positive and expressive NBs, respectively.

Expected results

+FE will have the largest placebo effects on pain and stress levels. However, transmitting the NBs to patients by VEs is challenging. Moreover, controlling for the effects of research assistants present in the testing room is challenging.

Discussion

We propose that caregivers' NBs affect pain reports and placebo effects. Moreover, different NBs elicit different impressions, and a better understanding of the role of caregiver NBs requires more rigorous investigations. Lastly, aiming to investigate the caregiver NBs, the varying degrees of micro-NBs and their effects on the formation of impressions should be considered.

Nocebo effects in visceral pain: concept and design of the experimental randomized-controlled pain study 'NoVis'

The role of psychological factors in the pathophysiology and treatment of chronic visceral pain in disorders of gut-brain interactions (DGBI) is increasingly appreciated. Placebo research has underscored that expectations arising from the psychosocial treatment context and from prior experiences shape treatment responses. However, effects of negative expectations, i.e., nocebo effects, as they are likely crucial elements of DGBI patients' clinical reality, have thus far only rarely been investigated in the context of visceral pain, with untapped potential for improved prevention and treatment. The experimental randomized-controlled pain study "NoVis," carried out within the Collaborative Research Center (CRC) 289 ("Treatment Expectation"), aims to close gaps regarding the generation and persistence of nocebo effects in healthy volunteers. It is designed to elucidate effects of negative expectations in a multiple-threat paradigm with intensity-matched rectal distensions and cutaneous thermal stimuli, allowing to test nocebo effects in the visceral and somatic pain modalities. Negative expectations are experimentally induced by elements of doctor-patient communication (i.e., instruction) and/or by surreptitious amplification of symptom intensity (i.e., experience/learning) within a treatment context. Accordingly, the repeated measures between-subject design contains the between-group factors "treatment instruction" (negative vs. control) and "treatment experience" (negative vs. control), with volunteers randomized into four experimental groups undergoing several pain stimulation phases (repeated factor). This allows to compare the efficacy of instruction vs. experience, and more importantly, their combined effects on the magnitude of negative expectations and their impact on pain responses, which we expect will be greatest for the visceral modality. After a Baseline, short-term effects are assessed during a test phase accomplished on study day 1 (Test-1 Phase). To explore the persistence of effects, a second test phase is accomplished 1 week later (Test-2 Phase). Effects of negative expectations within and across pain modalities are assessed at the subjective and objective levels, with a focus on psychophysiological and neuroendocrine measures related to stress, fear, and anxiety. Since nocebo effects can play a considerable role in the generation, maintenance, or worsening of chronic visceral pain, and may even constitute risk factors for treatment failure, knowledge from experimental nocebo research has potential to improve treatment outcomes in DGBI and other clinical conditions associated with chronic visceral pain.

The relationship of perceived empathy with levels of pain intensity and incapability among patients visiting a musculoskeletal specialist

BACKGROUND

People that have more intense symptoms and greater incapability might have less rapport with the clinicians that care for them.

OBJECTIVE

This study tested the hypothesis that perceived clinician empathy is related to pain intensity and magnitude of incapability among people seeing a musculoskeletal specialist.

PATIENT INVOLVEMENT

After a consult with a musculoskeletal specialist, 211 adult patients completed a survey recording demographics, and measures of pain intensity, incapability, and perceived clinician empathy.

RESULTS

Higher perceived empathy was associated with being in a committed relationship and, to a modest degree (r = -0.16) lower pain intensity in bivariate and multivariable analyses.

DISCUSSION

People experiencing greater pain may be slightly less likely to perceive the clinician as empathetic.

PRACTICAL VALUE

Study of the relationship between the patient's experience of care and patient and clinician personal factors can inform efforts to improve patient experience. Advances may depend on experience measures with more normal distributions and less ceiling effect.

Randomized clinical trial: A phase 2b controlled study of the efficacy and safety of trazpiroben (TAK-906) for idiopathic or diabetic gastroparesis

BACKGROUND

Previous clinical studies of trazpiroben, a dopamine D2 /D3 receptor antagonist for long-term treatment of moderate-to-severe idiopathic and diabetic gastroparesis, have shown improved symptoms of fullness. This study assessed trazpiroben efficacy, safety, and tolerability in adults with idiopathic and diabetic gastroparesis versus placebo.

METHODS

This global, multicenter, double-blind, parallel-group, phase 2b study (NCT03544229) enrolled eligible adults aged 18-85 years with symptomatic idiopathic or diabetic gastroparesis. Randomized participants received either oral placebo or trazpiroben 5, 25, or 50 mg, administered twice daily over 12 weeks, and completed the American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index-Daily Diary. Change in weekly composite score from baseline to week 12 (primary endpoint) and treatment-emergent adverse events were assessed. Data were summarized descriptively.

KEY RESULTS

Overall, 242 participants were enrolled (mean [standard deviation] age 55.7 [14.2] years; 75.6% female); 193 completed the study. No significant differences in change from baseline in weekly average of the daily diary composite score occurred at week 12 between placebo (least-squares mean [standard error] -1.19 [0.12]) and trazpiroben (5, 25, and 50 mg: -1.11 [0.22], -1.17 [0.12], and -1.21 [0.12], respectively). Overall, 41.4% of participants receiving trazpiroben reported treatment-emergent adverse events (placebo, 39.7%). No serious events were considered trazpiroben-related; no life-threatening or fatal events were reported.

CONCLUSIONS & INFERENCES

There was no clinically meaningful difference in efficacy between trazpiroben and placebo in treating gastroparesis, based on the primary endpoint analysis. Trazpiroben was well tolerated with no new safety concerns identified, strengthening evidence supporting its favorable safety profile. NCT number: NCT03544229.

The Placebo Effect in Psychosis: Why It Matters and How to Measure It

Psychosis is characterized by unusual percepts and beliefs in the form of hallucinations and delusions. Antipsychotic medication, the primary treatment for psychosis, is often ineffective and accompanied by severe side effects, but research has not identified an effective alternative in several decades. One reason that clinical trials fail is that patients with psychosis tend to show a significant therapeutic response to inert control treatments, known as the placebo effect, which makes it difficult to distinguish drug effects from placebo effects. Conversely, in clinical practice, a strong placebo effect may be useful because it could enhance the overall treatment response. Identifying factors that predict large placebo effects could improve the future outlook of psychosis treatment. Biomarkers of the placebo effect have already been suggested in pain and depression, but not in psychosis. Quantifying markers of the placebo effect would have the potential to predict placebo effects in psychosis clinical trials. Furthermore, the placebo effect and psychosis may represent a shared neurocognitive mechanism in which prior beliefs are weighted against new sensory information to make inferences about reality. Examining this overlap could reveal new insights into the mechanisms underlying psychosis and indicate novel treatment targets. We provide a narrative review of the importance of the placebo effect in psychosis and propose a novel method to assess it.

Acupuncture for Patients with Chronic Spontaneous Urticaria: A Randomized, Sham-Controlled Pilot Trial

OBJECTIVE

To determine the feasibility of conducting a full-scale randomized controlled trial (RCT) and investigate the basic information and safety of acupuncture for patients with chronic spontaneous urticaria (CSU).

METHODS

A total of 80 participants with CSU from July 2018 to July 2019 were randomly assigned to receive active acupuncture (n=41) on a fixed prescription of acupoints or sham acupuncture (n=39) with superficial acupuncture on non-acupuncture points through the completely randomized design. Patients in both groups received 5 sessions per week for 2 weeks, and participants were followed for a further 2 weeks. Feasibility was assessed by recruitment and randomization rates, retention of participants, treatment protocol adherence, and the incidence of adverse events (AEs). The clinical primary outcome was the changes from baseline weekly urticaria activity scores (UAS7) after treatment at 2 weeks. Secondary outcomes included the Visual Analogue Scale (VAS) score of itching intensity, Dermatology Life Quality Index (DLQI), Hamilton Depression Scale (HAMD), and Hamilton Anxiety Scale (HAMA).

RESULTS

A total of 80 participants were enrolled. The recruitment rate of 24.02%, randomization rate of 100%, a loss rate of 6.25%, and no obvious AEs were observed in either group. The decrease from baseline in the mean UAS7 total score at week 2 in the active acupuncture group was -8.63 (95%CI, -11.78 to -5.49) and -6.21 (95%CI, -9.43 to -2.98) in the sham acupuncture group for a between-group difference of -2.42 (95% CI, -6.93 to 2.07). The change in the DLQI, VAS of itching intensity, HAMA, and HAMD were a slightly better improvement trend in the active acupuncture group than the sham acupuncture group, but the between-group difference was not significant.

CONCLUSIONS

Active acupuncture had a better improvement trend in alleviating symptoms, improving quality of life and regulating the mood of anxiety and depression in patients with CSU than sham acupuncture. (Registration Nos. AMCTR-ICR-18000190 and ChiCTR2100054776).

Placebo treatment affects brain systems related to affective and cognitive processes, but not nociceptive pain

Placebo analgesia is a replicable and well-studied phenomenon, yet it remains unclear to what degree it includes modulation of nociceptive processes. Some studies find effects consistent with nociceptive effects, but meta-analyses show that these effects are often small. We analyzed placebo analgesia in a large fMRI study (N = 392), including placebo effects on brain responses to noxious stimuli. Placebo treatment caused robust analgesia in both conditioned thermal and unconditioned mechanical pain. Placebo did not decrease fMRI activity in nociceptive pain regions, including the Neurologic Pain Signature (NPS) and pre-registered spinothalamic pathway regions, with strong support from Bayes Factor analyses. However, placebo treatment affected activity in pre-registered analyses of a second neuromarker, the Stimulus Intensity Independent Pain Signature (SIIPS), and several associated a priori brain regions related to motivation and value, in both thermal and mechanical pain. Individual differences in behavioral analgesia were correlated with neural changes in both thermal and mechanical pain. Our results indicate that processes related to affective and cognitive aspects of pain primarily drive placebo analgesia.

The role of the communicated treatment rationale on treatment outcome: study protocol for a randomized controlled trial

BACKGROUND

Placebo effects are a well-established phenomenon in the treatment of depression. However, the mechanism underlying these effects are not fully understood. Treatment expectations are considered one explanation for why placebos work. Treatment expectations are likely to be affected by clinician-patient interactions. This study aims to investigate the role of the communicated treatment rationale in modulating treatment expectations and its effects on the treatment outcomes of a pharmacological and a psychological active placebo intervention for depression. In this study, treatment expectations are modulated by presenting illness models that are either congruent or incongruent with the treatment intervention that follows.

METHODS

This 2 × 2 randomized controlled trial will involve patients with major depression. Participants will either receive a biological or a psychological illness model from a clinician. Following this, they are randomly assigned to receive either a pharmacological or a psychological active placebo intervention. The illness model and the treatment are either congruent or incongruent with each other, resulting in four groups. In addition, a natural course control group will be included.

DISCUSSION

This study will provide insights into the mechanism of expectation modulation in active placebo treatments for major depression. The results may provide insights for clinicians to improve their communication with patients by focusing on treatment expectations. By identifying the factors that contribute to placebo effects, this study has the potential to improve the effectiveness of existing depression treatments and reduce the burden of this highly prevalent mental health condition.

TRIAL REGISTRATION

This trial has been registered prospectively at ClinicalTrials.gov under the identifier: NCT04719663. Registered on January 22, 2021.

Up-Front Endoscopy Maximizes Cost-Effectiveness and Cost-Satisfaction in Uninvestigated Dyspepsia

BACKGROUND & AIMS

Practice guidelines promote a routine noninvasive, non-endoscopic initial approach to investigating dyspepsia without alarm features in young patients, yet many patients undergo prompt upper endoscopy. We aimed to assess tradeoffs among costs, patient satisfaction, and clinical outcomes to inform discrepancy between guidelines and practice.

METHODS

We constructed a decision-analytic model and performed cost-effectiveness/cost-satisfaction analysis over a 1-year time horizon on patients with uninvestigated dyspepsia without alarm features referred to gastroenterology. A RAND/UCLA expert panel informed model design. Four competing diagnostic/management strategies were evaluated: prompt endoscopy, testing for Helicobacter pylori and eradicating if present (test-and-treat), testing for H pylori and performing endoscopy if present (test-and-scope), and empiric acid suppression. Outcomes were derived from systematic reviews of clinical trials. Costs were informed by prospective observational cohort studies and national commercial/federal cost databases. Health gains were represented using quality-adjusted life years.

RESULTS

From the patient perspective, costs and outcomes were similar for all strategies (maximum out-of-pocket difference of $30 and <0.01 quality-adjusted life years gained/year regardless of strategy). Prompt endoscopy maximized cost-satisfaction and health system reimbursement. Test-and-scope maximized cost-effectiveness from insurer and patient perspectives. Results remained robust on multiple one-way sensitivity analyses on model inputs and across most willingness-to-pay thresholds.

CONCLUSIONS

Noninvasive management strategies appear to result in inferior cost-effectiveness and patient satisfaction outcomes compared with strategies promoting up-front endoscopy. Therefore, additional studies are needed to evaluate the drivers of patient satisfaction to facilitate inclusion in value-based healthcare transformation efforts.

Brain-to-brain mechanisms underlying pain empathy and social modulation of pain in the patient-clinician interaction

Social interactions such as the patient-clinician encounter can influence pain, but the underlying dynamic interbrain processes are unclear. Here, we investigated the dynamic brain processes supporting social modulation of pain by assessing simultaneous brain activity (fMRI hyperscanning) from chronic pain patients and clinicians during video-based live interaction. Patients received painful and nonpainful pressure stimuli either with a supportive clinician present (Dyadic) or in isolation (Solo). In half of the dyads, clinicians performed a clinical consultation and intake with the patient prior to hyperscanning (Clinical Interaction), which increased self-reported therapeutic alliance. For the other half, patient-clinician hyperscanning was completed without prior clinical interaction (No Interaction). Patients reported lower pain intensity in the Dyadic, relative to the Solo, condition. In Clinical Interaction dyads relative to No Interaction, patients evaluated their clinicians as better able to understand their pain, and clinicians were more accurate when estimating patients' pain levels. In Clinical Interaction dyads, compared to No Interaction, patients showed stronger activation of the dorsolateral and ventrolateral prefrontal cortex (dlPFC and vlPFC) and primary (S1) and secondary (S2) somatosensory areas (Dyadic-Solo contrast), and clinicians showed increased dynamic dlPFC concordance with patients' S2 activity during pain. Furthermore, the strength of S2-dlPFC concordance was positively correlated with self-reported therapeutic alliance. These findings support that empathy and supportive care can reduce pain intensity and shed light on the brain processes underpinning social modulation of pain in patient-clinician interactions. Our findings further suggest that clinicians' dlPFC concordance with patients' somatosensory processing during pain can be boosted by increasing therapeutic alliance.

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.

Catechol-O-Methyltransferase Loss Drives Cell-Specific Nociceptive Signaling via the Enteric Catechol-O-Methyltransferase/microRNA-155/Tumor Necrosis Factor α Axis

BACKGROUND & AIMS

The etiology of abdominal pain in postinfectious, diarrhea-predominant irritable bowel syndrome (PI-IBS-D) is unknown, and few treatment options exist. Catechol-O-methyltransferase (COMT), an enzyme that inactivates and degrades biologically active catecholamines, plays an important role in numerous physiologic processes, including modulation of pain perception. Our objective was to determine the mechanism(s) of how decreased colonic COMT in PI-IBS-D patients contributes to the chronic abdominal pain phenotype after enteric infections.

METHODS

Colon neurons, epithelial cells, and macrophages were procured with laser capture microdissection from PI-IBS-D patients to evaluate cell-specific colonic COMT, microRNA-155 (miR-155), and tumor necrosis factor (TNF) α expression levels compared to recovered patients (infection cleared: did not develop PI-IBS-D) and control individuals. COMT-/-, colon-specific COMT-/-, and miR-155-/- mice and human colonoids were used to model phenotypic expression of COMT in PI-IBS-D patients and to investigate signaling pathways linking abdominal pain. Citrobacter rodentium and trinitrobenzene sulfonic acid animal models were used to model postinflammatory changes seen in PI-IBS-D patients.

RESULTS

Colonic COMT levels were significantly decreased and correlated with increased visual analog scale abdominal pain ratings in PI-IBS-D patients compared to recovered patients and control individuals. Colonic miR-155 and TNF-α were increased in PI-IBS-D patients with diminished colonic COMT. COMT-/- mice had significantly increased expression of miR-155 and TNF-α in both colon tissues and dorsal root ganglia. Introduction of cV1q antibody (anti-TNF-α) into mice reversed visceral hypersensitivity after C rodentium and trinitrobenzene sulfonic acid.

CONCLUSIONS

Decreased colonic COMT in PI-IBS-D patients drives abdominal pain phenotypes via the COMT/miR-155/TNF-α axis. These important findings will allow new treatment paradigms and more targeted and personalized medicine approaches for gastrointestinal disorders after enteric infections.

Meta-analysis: Placebo rates in microscopic colitis randomised trials and applications for future drug development using a historical control arm

BACKGROUND

Effective medical therapies for patients with microscopic colitis (MC) who fail budesonide are lacking. However, conducting randomised controlled trials (RCTs) in MC has been challenging due to small sample sizes. Understanding placebo responses can help inform more efficient future trials.

AIMS

The aim of this study is to estimate clinical and histologic placebo response rates and to determine factors associated with placebo response in MC.

METHODS

EMBASE, MEDLINE, and CENTRAL were searched until 7 January 2022, to identify placebo-controlled RCTs in adult patients with MC. Clinical and histologic response in the placebo arms were pooled using random-effects models. Stratified analyses based on disease- and trial-level characteristics, leave-one-out meta-analysis, and cumulative meta-analysis were performed.

RESULTS

Twelve RCTs enrolling a total of 391 patients (placebo n = 163) with MC were included. Pooled clinical and histologic placebo response rates were 24.4% (95% CI: 12.4%-38.4%), I²  = 60.8%, p < 0.01, and 19.9% (95% CI: 5.3%-39.0%), I²  = 66.4%, p = 0.01 (tests for heterogeneity), respectively. Clinical response to placebo was numerically higher in patients with lymphocytic compared to collagenous colitis (39.9% vs. 19.8%, p = 0.08). Heterogeneity in clinical response to placebo was significantly reduced when the Miehlke 2014 RCT was excluded in the leave-one-out meta-analysis or when a more stringent secondary definition of response based on the Hjortswang criteria was applied.

CONCLUSIONS

Approximately one-quarter of patients in MC trials respond to placebo, although with substantial heterogeneity, reflecting the need for standardised outcome definitions and study designs for MC. This analysis also serves to inform future MC trials that may consider incorporating an external, historical placebo control arm, rather than directly randomising patients to placebo.