Placebo effects and their determinants in gastrointestinal disorders

Persistent physical symptoms: definition, genesis, and management

Persistent physical symptoms (synonymous with persistent somatic symptoms) is an umbrella term for distressing somatic complaints that last several months or more, regardless of their cause. These symptoms are associated with substantial disability and represent a major burden for patients, health-care professionals, and society. Persistent physical symptoms can follow infections, injuries, medical diseases, stressful life events, or arise de novo. As symptoms persist, their link to clearly identifiable pathophysiology often weakens, making diagnosis and treatment challenging. Multiple biological and psychosocial risk factors and mechanisms contribute to the persistence of somatic symptoms, including persistent inflammation; epigenetic profiles; immune, metabolic and microbiome dysregulation; early adverse life experiences; depression; illness-related anxiety; dysfunctional symptom expectations; symptom focusing; symptom learning; and avoidance behaviours, with many factors being common across symptoms and diagnoses. Basic care consists of addressing underlying pathophysiology and using person-centred communication techniques with validation, appropriate reassurance, and biopsychosocial explanation. If basic care is insufficient, targeted psychological and pharmacological interventions can be beneficial. A better understanding of the multifactorial persistence of somatic symptoms should lead to more specific, personalised, and mechanism-based treatment, and a reduction in the stigma patients commonly face.

Postprandial symptoms in disorders of gut-brain interaction and their potential as a treatment target

Postprandial, or meal-related, symptoms, such as abdominal pain, early satiation, fullness or bloating, are often reported by patients with disorders of gut-brain interaction, including functional dyspepsia (FD) or irritable bowel syndrome (IBS). We propose that postprandial symptoms arise via a distinct pathophysiological process. A physiological or psychological insult, for example, acute enteric infection, leads to loss of tolerance to a previously tolerated oral food antigen. This enables interaction of both the microbiota and the food antigen itself with the immune system, causing a localised immunological response, with activation of eosinophils and mast cells, and release of inflammatory mediators, including histamine and cytokines. These have more widespread systemic effects, including triggering nociceptive nerves and altering mood. Dietary interventions, including a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols, elimination of potential food antigens or gluten, IgG food sensitivity diets or salicylate restriction may benefit some patients with IBS or FD. This could be because the restriction of these foods or dietary components modulates this pathophysiological process. Similarly, drugs including proton pump inhibitors, histamine-receptor antagonists, mast cell stabilisers or even tricyclic or tetracyclic antidepressants, which have anti-histaminergic actions, all of which are potential treatments for FD and IBS, act on one or more of these mechanisms. It seems unlikely that food antigens driving intestinal immune activation are the entire explanation for postprandial symptoms in FD and IBS. In others, fermentation of intestinal carbohydrates, with gas release altering reflex responses, adverse reactions to food chemicals, central mechanisms or nocebo effects may dominate. However, if the concept that postprandial symptoms arise from food antigens driving an immune response in the gastrointestinal tract in a subset of patients is correct, it is paradigm-shifting, because if the choice of treatment were based on one or more of these therapeutic targets, patient outcomes may be improved.

The effect of expectancy versus actual gluten intake on gastrointestinal and extra-intestinal symptoms in non-coeliac gluten sensitivity: a randomised, double-blind, placebo-controlled, international, multicentre study

BACKGROUND

Many individuals without coeliac disease or wheat allergy reduce their gluten intake because they believe that gluten causes their gastrointestinal symptoms. Symptoms could be affected by negative expectancy. Therefore, we aimed to investigate the effects of expectancy versus actual gluten intake on symptoms in people with non-coeliac gluten sensitivity (NCGS).

METHODS

This randomised, double-blind, placebo-controlled, international, multicentre study was done at the University of Leeds (Leeds, UK), Maastricht University (Maastricht, the Netherlands), and Wageningen University and Research (Wageningen, the Netherlands). People aged 18-70 years with self-reported NCGS (ie, gastrointestinal symptoms within 8 h of gluten consumption) without coeliac disease and wheat allergy were recruited. Participants had to follow a gluten-free or gluten-restricted diet for at least 1 week before (and throughout) study participation and had to be asymptomatic or mildly symptomatic (overall gastrointestinal symptom score ≤30 mm on the Visual Analogue Scale [VAS]) while on the diet. Participants were randomly assigned (1:1:1:1; blocks of eight; stratified by site and gender) to one of four groups based on the expectation to consume gluten-containing (E+) or gluten-free (E-) oat bread for breakfast and lunch (two slices each) and actual intake of gluten-containing (G+) or gluten-free (G-) oat bread. Participants, investigators, and those assessing outcomes were masked to the actual gluten assignment, and participants were also masked to the expectancy part of the study. The primary outcome was overall gastrointestinal symptom score on the VAS, which was measured at and corrected for baseline (before breakfast) and hourly for 8 h, with lunch served after 4 h, and analysed per-protocol. Safety analysis included all participants incorporated in the per-protocol analysis. The study is registered at ClinicalTrials.gov, NCT05779358, and has ended.

FINDINGS

Between Oct 19, 2018, and Feb 14, 2022, 165 people were screened and 84 were randomly assigned to E+G+ (n=21), E+G- (n=21), E-G+ (n=20), or E-G- (n=22). One person in the E+G+ group was excluded due to not following test day instructions, leaving 83 participants in the per-protocol analysis. Median age was 27·0 years (IQR 21·0-45·0), 71 (86%) of 83 people were women, and 12 (14%) were men. Mean overall gastrointestinal symptom score was significantly higher for E+G+ (16·6 mm [95% CI 13·1 to 20·0]) than for E-G+ (6·9 mm [3·5 to 10·4]; difference 9·6 mm [95% CI 3·0 to 16·2], p=0·0010) and E-G- (7·4 mm [4·2 to 10·7]; difference 9·1 mm [2·7 to 15·6], p=0·0016), but not for E+G- (11·7 mm [8·3 to 15·1]; difference 4·9 mm [-1·7 to 11·5], p=0·28). There was no difference between E+G- and E-G+ (difference 4·7 mm [-1·8 to 11·3], p=0·33), E+G- and E-G- (difference 4·2 mm [-2·2 to 10·7], p=0·47), and E-G+ and E-G- (difference -0·5 mm [-7·0 to 5·9], p=1·0). Adverse events were reported by two participants in the E+G- group (itching jaw [n=1]; feeling lightheaded and stomach rumbling [n=1]) and one participant in the E-G+ group (vomiting).

INTERPRETATION

The combination of expectancy and actual gluten intake had the largest effect on gastrointestinal symptoms, reflecting a nocebo effect, although an additional effect of gluten cannot be ruled out. Our results necessitate further research into the possible involvement of the gut-brain interaction in NCGS.

FUNDING

Government of the Netherlands Topsector Agri & Food Top Consortium for Knowledge and Innovation, AB Mauri Global Bakery Ingredients, Baking Industry Research Trust, Borgesius-Albert Heijn, CSM Innovation Centre, the International Maize and Wheat Improvement Center (CIMMYT), DSM Food Specialties, Fazer, Healthgrain Forum, the International Association for Cereal Science and Technology, the International Wheat Gluten Association, Lantmännen, Mondelez International, Nederlands Bakkerij Centrum, Nutrition & Santé, Puratos, Rademaker, Sonneveld Group, and Zeelandia HJ Doeleman.

Food intolerance related to gastrointestinal symptoms amongst adults living with bile acid diarrhoea: A cross-sectional study

BACKGROUND

The role of food in managing bile acid diarrhoea (BAD) is poorly understood. The present study explored the prevalence of food intolerance amongst adults with BAD.

METHODS

The study comprised a cross-sectional survey of adults with BAD determined by the 75 selenium homotaurocholic acid test (SeHCAT) living in the UK. Participants anonymously completed an online questionnaire on 39 food items. Frequency of food in general affecting BAD symptoms, as well as frequencies of diarrhoea, abdominal pain, bloating, flatulence and consequential food avoidance after food item ingestion, were assessed. Food group avoidance was also assessed.

RESULTS

There were 434 participants who completed the questionnaire between April and May 2021 of whom 80% reported moderate to severe chronic diarrhoea. Food intolerances were reported by 88.0% (95% confidence interval [CI] = 84.6-90.9) of participants. Diarrhoea was reported most frequently after take-away food, fish and chips, creamy sauces, cream and large quantities of fruit (range 41.0%-33.6%). Lowest frequencies were for potato, avocado, mango, watermelon and pear (range 3.7%-7.4%) for the foods listed in the questionnaire. Similar trends were found for abdominal pain, bloating, flatulence and consequential food avoidance. Symptom-triggering within 30 min of ingestion was more prevalence than after 30 min for almost all foods. Food group avoidance was highest for fatty foods (81.2%; 95% CI = 77.8-85.3) followed by dairy (53.9%; 95% CI = 49.1-58.7).

CONCLUSIONS

Perceived food intolerance amongst adults with BAD and persisting diarrhoeal symptoms is high. Important triggers were meals with a higher fat content and higher-fat dairy products. Diets amongst those with persisting diarrhoeal symptoms may be overly restrictive.

The Efficacy of Tradipitant in Patients With Diabetic and Idiopathic Gastroparesis in a Phase 3 Randomized Placebo-Controlled Clinical Trial

BACKGROUND

Neurokinin receptor 1 antagonists are effective in reducing nausea and vomiting in chemotherapy-induced emesis. We investigated the safety and efficacy of tradipitant, a neurokinin receptor 1 antagonist, in patients with idiopathic and diabetic gastroparesis.

METHODS

A total of 201 adults with gastroparesis were randomly assigned to oral tradipitant 85 mg (n = 102) or placebo (n = 99) twice daily for 12 weeks. Symptoms were assessed by a daily symptom dairy, Gastroparesis Cardinal Symptom Index scores, and other patient-reported questionnaires. Blood levels were monitored for an exposure-response analysis. The primary outcome was change from baseline to week 12 in average nausea severity, measured by daily symptom diary.

RESULTS

The intention-to-treat (ITT) population did not meet the prespecified primary endpoint at week 12 (difference in nausea severity change drug vs placebo; P = .741) or prespecified secondary endpoints. Post hoc analyses were performed to control for drug exposure, rescue medications, and baseline severity inflation. Subjects with high blood levels of tradipitant significantly improved average nausea severity beginning at early time points (weeks 2-4). In post hoc sensitivity analyses, tradipitant treatment demonstrated strengthened effects, with statistically significant improvements in nausea at week 12.

CONCLUSIONS

Although tradipitant did not reach significance in the ITT population, a pharmacokinetic exposure-response analysis demonstrated significant effects with adequate tradipitant exposure. When accounting for confounding factors such as baseline severity inflation and rescue medication, a statistically significant effect was also observed. These findings suggest that tradipitant has potential as a treatment for the symptom of nausea in gastroparesis. (ClincialTrials.gov, Number: NCT04028492).

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Optimal measurement of gastric emptying of solids in gastroparesis or functional dyspepsia: evidence to establish standard test

OBJECTIVE

Symptoms in gastroparesis (Gp) and functional dyspepsia (FD) overlap; using egg protein substitute to measure gastric emptying of solids (GES), ~40% of patients are reclassified from Gp to FD, and vice versa. Our aim was to assess inter-individual and intra-individual coefficients of variation (COV) in GES in symptomatic patients with Gp or FD with documented slow or normal GES, respectively.

DESIGN

Scintigraphic GES (T1/2 and GE% at 2 and 4 hours) using a 320 kcal real egg meal (30% fat) was tested in the following: single measurements in 20 patients with diabetes mellitus (10 each type 1 and type 2); repeat GES to estimate COVintra measured: 3 days apart in 9 Gp, 4 weeks apart in 21 Gp and 18 with FD with normal GE assigned to placebo and in 70 patients at 94.3 weeks (median) apart.

RESULTS

COVinter for GE% at 4 hours and GE T1/2 were respectively 14.2% and 23.5% in FD and 27.5% and 33% in Gp; COVintra for GE% at 4 hours and GE T1/2 up to 4 weeks apart were 23.4% and 37.9% in FD and 20.1% and 33% in Gp. GE% at 2 hours showed less consistent results. However, >85% retained original diagnosis as normal or delayed. From clinical GES to baseline research for Gp group, repeat GES (after treatment) showed the COVintra for GE% at 4 hours was 37.3% at median 94.3 weeks, with 26/70 changed diagnoses.

CONCLUSION

The 320 kcal (30% fat) GES scintigraphic test provides consistent diagnosis in >85% and should be the standard test for suspected gastric emptying disorders.

Psychological risk factors for Long COVID and their modification: study protocol of a three-arm, randomised controlled trial (SOMA.COV)

BACKGROUND

Growing evidence suggests that in addition to pathophysiological, there are psychological risk factors involved in the development of Long COVID. Illness-related anxiety and dysfunctional symptom expectations seem to contribute to symptom persistence.

AIMS

With regard to the development of effective therapies, our primary aim is to investigate whether symptoms of Long COVID can be improved by a targeted modification of illness-related anxiety and dysfunctional symptom expectations. Second, we aim to identify additional psychosocial risk factors that contribute to the persistence of Long COVID, and compare them with risk factors for symptom persistence in other clinical conditions.

METHOD

We will conduct an observer-blinded, three-arm, randomised controlled trial. A total of 258 patients with Long COVID will be randomised into three groups of equal size: targeted expectation management in addition to treatment as usual (TAU), non-specific supportive treatment plus TAU, or TAU only. Both active intervention groups will comprise three individual online video consultation sessions and a booster session after 3 months. The primary outcome is baseline to post-interventional change in overall somatic symptom severity.

CONCLUSIONS

The study will shed light onto the action mechanisms of a targeted expectation management intervention for Long COVID, which, if proven effective, can be used stand-alone or in the context of broader therapeutic approaches. Further, the study will enable a better understanding of symptom persistence in Long COVID by identifying additional psychological risk factors.

Placebo and nocebo effects and mechanisms associated with pharmacological interventions: an umbrella review

OBJECTIVES

This review aimed to summarise the existing knowledge about placebo and nocebo effects associated with pharmacological interventions and their mechanisms.

DESIGN

Umbrella review, adopting the Assessment of Multiple Systematic Reviews 2 tool for critical appraisal.

DATA SOURCES

MEDLINE/PubMed, Scopus, Web of Science, PsycINFO, Cochrane Central Register of Controlled Trial were searched in September 2022, without any time restriction, for systematic reviews, narrative reviews, original articles. Results were summarised through narrative synthesis, tables, 95% CI.

OUTCOME MEASURES

Mechanisms underlying placebo/nocebo effects and/or their effect sizes.

RESULTS

The databases search identified 372 studies, for a total of 158 312 participants, comprising 41 systematic reviews, 312 narrative reviews and 19 original articles. Seventy-three per cent of the examined systematic reviews were of high quality.Our findings revealed that mechanisms underlying placebo and/or nocebo effects have been characterised, at least in part, for: pain, non-noxious somatic sensation, Parkinson's disease, migraine, sleep disorders, intellectual disability, depression, anxiety, dementia, addiction, gynaecological disorders, attention-deficit hyperactivity disorder, immune and endocrine systems, cardiovascular and respiratory systems, gastrointestinal disorders, skin diseases, influenza and related vaccines, oncology, obesity, physical and cognitive performance. Their magnitude ranged from 0.08 to 2.01 (95% CI 0.37 to 0.89) for placebo effects and from 0.32 to 0.90 (95% CI 0.24 to 1.00) for nocebo effects.

CONCLUSIONS

This study provides a valuable tool for clinicians and researchers, identifying both results ready for clinical practice and gaps to address in the near future.

FUNDING

Università Cattolica del Sacro Cuore, Milan, Italy with the 'Finanziamento Ponte 2022' grant.

PROSPERO REGISTRATION NUMBER

CRD42023392281.

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.

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.

IBS randomized study: FODMAPs alter bile acids, phenolic- and tryptophan metabolites, while gluten modifies lipids

Diet is considered a culprit for symptoms in irritable bowel syndrome (IBS), although the mechanistic understanding of underlying causes is lacking. Metabolomics, i.e., the analysis of metabolites in biological samples may offer a diet-responsive fingerprint for IBS. Our aim was to explore alterations in the plasma metabolome after interventions with fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) or gluten versus control in IBS, and to relate such alterations to symptoms. People with IBS (n = 110) were included in a double-blind, randomized, crossover study with 1-wk provocations of FODMAPs, gluten, or placebo. Symptoms were evaluated with the IBS severity scoring system (IBS-SSS). Untargeted metabolomics was performed on plasma samples using LC-qTOF-MS. Discovery of metabolite alterations by treatment was performed using random forest followed by linear mixed modeling. Associations were studied using Spearman correlation. The metabolome was affected by FODMAP [classification rate (CR) 0.88, P < 0.0001], but less by gluten intake CR 0.72, P = 0.01). FODMAP lowered bile acids, whereas phenolic-derived metabolites and 3-indolepropionic acid (IPA) were higher compared with placebo. IPA and some unidentified metabolites correlated weakly to abdominal pain and quality of life. Gluten affected lipid metabolism weakly, but with no interpretable relationship to IBS. FODMAP affected gut microbial-derived metabolites relating to positive health outcomes. IPA and unknown metabolites correlated weakly to IBS severity. Minor symptom worsening by FODMAP intake must be weighed against general positive health aspects of FODMAP. The gluten intervention affected lipid metabolism weakly with no interpretable association to IBS severity. Registration: www.clinicaltrials.gov as NCT03653689.NEW & NOTEWORTHY In irritable bowel syndrome (IBS), fermentable oligo-, di-, monosaccharides, and polyols (FODMAPs) affected microbial-derived metabolites relating to positive health outcomes such as reduced risk of colon cancer, inflammation, and type 2 diabetes, as shown in previous studies. The minor IBS symptom induction by FODMAP intake must be weighed against the positive health aspects of FODMAP consumption. Gluten affected lipids weakly with no association to IBS severity.

Predictors of Clinical Remission to Placebo in Clinical Trials of Crohn's Disease

BACKGROUND

In placebo-controlled clinical trials for Crohn's disease (CD), some placebo-treated patients demonstrate improvement. However, it is unclear what factors contribute to placebo response and remission.

METHODS

This was a post hoc analysis of 3 placebo-controlled clinical trial programs (GEMINI-2, UNITI-1/2, and CLASSIC-1) of moderate-severe CD evaluating the efficacy of vedolizumab, ustekinumab, and adalimumab. Baseline predictors of clinical remission at the end of induction (week 4/6), defined as Crohn's Disease Activity Index <150 were evaluated among placebo-treated patients. Clinical response (decrease in Crohn's Disease Activity Index ≥100 points from baseline) at the end of induction was also evaluated. Univariate analyses were performed and predictors with P < .10 were included in multivariable analyses.

RESULTS

A total of 683 patients (148 from GEMINI-2, 470 from UNITI-1/2, and 65 from CLASSIC-1) treated with placebo were included. Of the predictors evaluated, C-reactive protein <5 mg/L (odds ratio [OR], 1.66; 95% confidence interval [CI], 1.04-2.67; P = .035), albumin >40 g/L (OR, 1.57; 95% CI, 1.05-2.93; P = .023), and disease duration <5 years (OR, 1.70; 95% CI, 1.05-2.75; P = .032) were included in the multivariable model for clinical remission. Disease duration <5 years was the only variable that retained significance on multivariable analysis (adjusted OR, 1.67; 95% CI, 1.02-2.73; P = .040). For clinical response, isolated ileal disease and disease duration <1 year were included in the multivariable model, of which only the latter retained significance (adjusted OR, 1.84; 95% CI, 1.04-3.24; P = .035).

CONCLUSIONS

Strategies that reduce placebo response rates in clinical trials of CD should be considered, including stratification or exclusion of subjects by disease duration and mild disease severity as measured by objective biomarkers.

Placebo and Nocebo Effects as Bayesian-Brain Phenomena: The Overlooked Role of Likelihood and Attention

The Bayesian-brain framework applied to placebo responses and other mind-body interactions suggests that the effects on the body result from the interaction between priors, such as expectations and learning, and likelihood, such as somatosensorial information. Significant research in this area focuses on the role of the priors, but the relevance of the likelihood has been surprisingly overlooked. One way of manipulating the relevance of the likelihood is by paying attention to sensorial information. We suggest that attention can influence both precision and position (i.e., the relative distance from the priors) of the likelihood by focusing on specific components of the somatosensorial information. Two forms of attention seem particularly relevant in this framework: mindful attention and selective attention. Attention has the potential to be considered a "major player" in placebo/nocebo research, together with expectations and learning. In terms of application, relying on attentional strategies as "amplifiers" or "silencers" of sensorial information could lead to an active involvement of individuals in shaping their care process and health. In this contribution, we discuss the theoretical implications of these intuitions with the aim to provide a comprehensive framework that includes Bayesian brain, placebo/nocebo effects, and the role of attention in mind-body interactions.

The Impact of a Twelve-Week Moderate Aerobic Exercise Program on Gastrointestinal Symptom Profile and Psychological Well-Being of Irritable Bowel Syndrome Patients: Preliminary Data from a Southern Italy Cohort

Walking is popular moderate-intensity aerobic exercise that improves mental and gastrointestinal (GI) health. It can relieve symptoms associated with irritable bowel syndrome (IBS), e.g., intestinal gas, abdominal distension, and bowel disturbances. This study examined the impact of a moderate-intensity aerobic exercise program on the clinical and psychological parameters of IBS patients. In total, 40 IBS patients (11 males and 29 females; mean age 51.9 ± 7.8 years) participated in a 12-week aerobic exercise program. Participants completed questionnaires assessing GI symptoms, psychological profiles, and quality of life (QoL) before and after the intervention. Field tests, anthropometric measurements, and bioimpedance assessments were also conducted. The present findings confirmed a significant improvement in IBS symptoms after the aerobic exercise program. Bloating was the most common symptom and, together with abdominal pain, was significantly reduced after treatment. Psychological and QoL questionnaires indicated decreased anxiety, depression, somatization, and stress levels. Correlations were found between anxiety/depression and the severity of abdominal pain as well as between stress and the severity of abdominal distension. Moderate-intensity aerobic exercise positively impacted GI symptoms and psychological well-being, complementing dietary and psychological support as a non-pharmacological therapy for the management of IBS. These findings emphasize the importance of alternative approaches for IBS treatment.

Effects of FODMAPs and Gluten on Gut Microbiota and Their Association with the Metabolome in Irritable Bowel Syndrome: A Double-Blind, Randomized, Cross-Over Intervention Study

BACKGROUND

A mechanistic understanding of the effects of dietary treatment in irritable bowel syndrome (IBS) is lacking. Our aim was therefore to investigate how fermentable oligo- di-, monosaccharides, and polyols (FODMAPs) and gluten affected gut microbiota and circulating metabolite profiles, as well as to investigate potential links between gut microbiota, metabolites, and IBS symptoms.

METHODS

We used data from a double-blind, randomized, crossover study with week-long provocations of FODMAPs, gluten, and placebo in participants with IBS. To study the effects of the provocations on fecal microbiota, fecal and plasma short-chain fatty acids, the untargeted plasma metabolome, and IBS symptoms, we used Random Forest, linear mixed model and Spearman correlation analysis.

RESULTS

FODMAPs increased fecal saccharolytic bacteria, plasma phenolic-derived metabolites, 3-indolepropionate, and decreased isobutyrate and bile acids. Gluten decreased fecal isovalerate and altered carnitine derivatives, CoA, and fatty acids in plasma. For FODMAPs, modest correlations were observed between microbiota and phenolic-derived metabolites and 3-indolepropionate, previously associated with improved metabolic health, and reduced inflammation. Correlations between molecular data and IBS symptoms were weak.

CONCLUSIONS

FODMAPs, but not gluten, altered microbiota composition and correlated with phenolic-derived metabolites and 3-indolepropionate, with only weak associations with IBS symptoms. Thus, the minor effect of FODMAPs on IBS symptoms must be weighed against the effect on microbiota and metabolites related to positive health factors.

Inflammation shapes neural processing of interoceptive fear predictors during extinction learning in healthy humans

Inflammation could impact on the formation and persistence of interoceptive fear and hypervigilance, with relevance to psychiatric disorders and chronic pain. To systematically analyze effects of inflammation on fear learning and extinction, we performed two complementary randomized, double-blind, placebo-controlled functional magnetic resonance imaging (fMRI) studies combining experimental endotoxemia as a translational model of acute systemic inflammation with a two-day multiple-threat fear conditioning paradigm involving interoceptive and exteroceptive unconditioned stimuli (US). Healthy volunteers (N = 95) were randomized to receive intravenous injections of either endotoxin (lipopolysaccharide, LPS; 0.4 ng/kg) or placebo prior to fear acquisition (study 1) or extinction training (study2). Treatment effects on behavioral and neural responses to conditioned stimuli (CS) predicting interoceptive or exteroceptive threat were assessed during fear learning and extinction phases, along with US valence ratings. Despite robust inflammatory and emotional responses triggered by LPS, no direct effects of inflammation on US ratings or on the formation or extinction of conditioned fear, as assessed with CS valence ratings, were observed. However, in the group treated with LPS prior to acquisition (i.e., study 1), we found enhanced neural responses to the interoceptive but not the exteroceptive CS in key regions of the central fear circuitry during extinction learning. After extinction, this group further showed enhanced negative valence ratings selectively for the interoceptive US during unexpected US re-exposure when compared to the placebo group. Together, inflammation during fear acquisition may promote the establishment of a more robust neural signature of the interoceptive fear memory trace, which may contribute to altered interoceptive pain perception. The fear extinction circuitry engaged during interoceptive fear memory processing may be particularly vulnerable to inflammation, with transdiagnostic implications for gut-brain mechanisms underlying disturbed interoception in psychiatric conditions and chronic visceral pain.

Placebo effects in functional dyspepsia: Causes and implications for clinical trials

Placebo responses to an apparently inactive intervention are of interest from a scientific perspective as they suggest possible mechanism(s) at work beyond the intervention itself. They are also of interest from a clinical trials perspective since high rates of placebo response limit the potential to demonstrate worthwhile efficacy of a new intervention. This mini-review was motivated by the work of Bosman and colleagues(Neurogastroenterol Motil, 2022, and e14474) that is published in this issue of the journal in which they report on a systematic review and meta-analysis of placebo response in functional dyspepsia clinical trials. The review sets the scene for their work by putting it in the context of other disorders of brain-gut interaction and extra-gastrointestinal disorders. The review canvasses potential mechanisms of placebo response.

Wenn aus einem Bauchgefühl viszerale Schmerzen werden: Placebo- und Nocebo-Mechanismen entlang der Darm-Hirn-Achse

Das Erleben von Schmerz ist nach heutigem Verständnis durch eine Vielzahl biologischer, psychologischer und sozialer Faktoren geprägt und somit eine komplexe, von der Nozizeption abzugrenzende, psychologische Erfahrung. Entsprechend ist das Schmerzerleben durch psychologische Faktoren modulierbar und chronische Schmerzen werden als biopsychosoziale Erkrankungen verstanden. Dies gilt auch für den Viszeralschmerz, dem spezifische psychophysiologische Prinzipien und neurobiologische Mechanismen zugrunde liegen, was eine interdisziplinäre Betrachtung unter Einbeziehung der Psychologie und der Neurowissenschaften erforderlich macht. Ausgehend von den bidirektionalen Verbindungen zwischen Darm und Hirn und aufbauend auf einem biopsychosozialen Krankheitsmodell beschreibt dieser Übersichtsbeitrag psychologische Mechanismen, die bei der Entstehung, Aufrechterhaltung und Therapie viszeraler Schmerzen wichtig sind. Dabei liegt der Fokus auf positiven und negativen Erwartungseffekten im psychosozialen Behandlungskontext. Therapieerwartungen können Krankheitssymptome sowohl positiv als auch negativ beeinflussen. Diese gemeinhin als Placebo- und Noceboeffekte bekannten Phänomene, die durch die Arzt-Patient Kommunikation, Lernprozesse, Stress und Furcht vermittelt werden, sind auch für den Viszeralschmerz bei gastrointestinalen Erkrankungen zunehmend anerkannt und Gegenstand aktueller grundlagenwissenschaftlicher und klinischer Forschungsaktivitäten. Neue interdisziplinäre und translationale Forschungsansätze aus der Forschung zu Placebo- und Noceboeffekten liefern spannende Einblicke in die zahlreichen Verbindungen und Wechselbeziehungen zwischen Darm und Gehirn bei normalen wie auch pathologischen Darm-Hirn Interaktionen und können dazu beitragen, die Pathophysiologie von Erkrankungen, die mit viszeralen Schmerzen einhergehen, besser zu verstehen und wichtige Erkenntnisse für neue Therapieansätze zu gewinnen.

Placebo response in pharmacological trials in patients with functional dyspepsia-A systematic review and meta-analysis

BACKGROUND

Pharmacological trials in functional dyspepsia (FD) are associated with high placebo response rates. We aimed to identify the magnitude and contributing factors to the placebo response.

METHODS

We conducted a systematic review and meta-analysis including randomized controlled trials (RCTs) with a dichotomous outcome in adult patients with FD that compared an active pharmacotherapeutic treatment with placebo. Our main outcome was identification of the magnitude of the pooled placebo response rate for the following endpoints: symptom responder, symptom-free responder, adequate relief responder, and combined endpoint responder (i.e., the primary endpoint of each specific trial regarding treatment response). Several putative moderators (i.e., patient, disease, and trial characteristics) were examined.

KEY RESULTS

We included 26 RCTs in our analysis. The pooled placebo response rate was 39.6% (95% CI 30.1-50.0) using the symptom responder definition, 20.5% (12.8-31.0) using the symptom-free responder definition, 38.5% (33.8-43.6) using the adequate relief responder definition, and 35.5% (31.6-39.7) using the combined endpoint responder definition. A lower overall baseline symptom score was significantly associated with a higher placebo response rate. No other moderators were found to significantly impact the placebo response rate. Due to the lack of data, no analyses could be performed according to individual FD subtypes or symptoms.

CONCLUSIONS AND INFERENCES

The pooled placebo response rate in pharmacological trials in FD is about 39%, depending on which responder definitions is used. Future trials should consider applying an entry criterion based on minimal level of symptom severity to decrease the placebo response. We also suggest separate reporting of core FD symptoms pending more concrete harmonization efforts in FD trials.

Efficacy and Safety of the Adjuvant Use of Probiotic Bacillus clausii Strains in Pediatric Irritable Bowel Syndrome: A Randomized, Double-Blind, Placebo-Controlled Study

OBJECTIVES

Current irritable bowel syndrome (IBS) treatments have limited efficacy and probiotics like Bacillus clausii (B. clausii) were found to be effective in the management of several gastrointestinal disorders. This phase III trial assessed the efficacy and safety of adding B. clausii (four strains: O/C, N/R, SIN, T), versus placebo, to conventional treatment of pediatric IBS in Mexico.

METHODS

Patients aged 6-17 years 11 months with IBS (Rome IV) for at least 2 months were randomized to receive either B. clausii (oral suspension, total dose 4 billion spores/day) or placebo once daily for 8 weeks. All patients also received conventional treatment. The primary endpoint was the difference in the proportion of patients with clinical improvements at Week 8 (Global Assessment Questions [GAQ]). Secondary endpoints included responders by Subject's Global Assessment of Relief for Children with IBS (SGARC); number/consistency of stools; abdominal distention/bloating; abdominal pain/intensity; and IBS behavior.

RESULTS

73.6% (95% confidence interval [CI] 67.3-80.0; B. clausii n = 129) and 78.5% (95% CI 72.5-84.4; placebo n = 130) of patients had symptom improvement (p = 0.8182). For Week 8 SGARC, 19.2% (B. clausii) and 20.9% (placebo) reported complete symptom relief. Stool evaluations, bloating, abdominal pain/intensity, and IBS behavior were similar between groups. Both treatments were well tolerated.

CONCLUSION

No significant differences in efficacy between B. clausii and placebo were demonstrated in addition to conventional treatment. The sample size calculation was based on an expected placebo/conventional treatment response of 30-40%. However, the actual treatment response observed was 80% and, thus, a study with larger population would be warranted. In addition, this study was conducted during the COVID-19 pandemic, when such controlled social conditions may have resulted in better diet, greater family stability, less psychological stress, and lower risk of infections exacerbating IBS, thereby improving symptoms in both groups.

EUDRACT NUMBER

2018-004519-31.

A postbiotic fermented oat gruel may have a beneficial effect on the colonic mucosal barrier in patients with irritable bowel syndrome

Background

Impaired intestinal permeability and microbial dysbiosis are important pathophysiological mechanisms underlying irritable bowel syndrome (IBS). ReFerm^®, also called Profermin^®, is a postbiotic product of oat gruel fermented with Lactobacillus plantarum 299v. In this study, we investigated whether ReFerm^® has a beneficial effect on the intestinal epithelial barrier function in patients with IBS.

Materials and methods

Thirty patients with moderate to severe IBS-diarrhoea (IBS-D) or IBS-mixed (IBS-M) were treated with enema containing ReFerm^® or placebo. The patients underwent sigmoidoscopy with biopsies obtained from the distal colon at baseline and after 14 days of treatment with ReFerm^® or placebo twice daily. The biopsies were mounted in Ussing chambers, and paracellular and transcellular permeabilities were measured for 120 min. In addition, the effects of ReFerm^® or placebo on the epithelial barrier were investigated in vitro using Caco-2 cells.

Results

ReFerm^® reduced paracellular permeability (p < 0.05) and increased transepithelial resistance (TER) over time (p < 0.01), whereas the placebo had no significant effect in patients. In ReFerm^®-treated Caco-2 cells, paracellular and transcellular permeabilities were decreased compared to the control (p < 0.05) and placebo (p < 0.01). TER was increased in Caco-2 ReFerm^®-treated cells, and normalised TER was increased in ReFerm^®-treated Caco-2 cells compared to control (p < 0.05) and placebo-treated (p < 0.05) cells.

Conclusion

ReFerm^® significantly reduced paracellular permeability and improved TER in colonic biopsies collected from patients with IBS and in a Caco-2 cell model. Our results offer new insights into the potential benefits of ReFerm^® in IBS management. Further studies are needed to identify the molecular mechanisms underlying the barrier-protective properties of ReFerm^®.

Clinical trial registration

[https://clinicaltrials.gov/], identifier [NCT05475314].

Efficacy of a Digital Personalized Elimination Diet for the Self-Management of Irritable Bowel Syndrome and Comorbid Irritable Bowel Syndrome and Inflammatory Bowel Disease

INTRODUCTION

Most patients with irritable bowel syndrome (IBS) and dual-diagnosis IBS and inflammatory bowel disease (IBD) report that symptoms originate from or are exacerbated by trigger foods. Despite patient interest and need, there is no consensus on what diet is optimal. Popular diets have notable limitations including cost, length, implementation complexity, and lack of personalization.

METHODS

This pilot study evaluated the feasibility, desirability, and effect on gastrointestinal symptoms of a digitally delivered personalized elimination diet for patients with IBS and comorbid IBS/IBD, powered by machine learning. Participants were recruited online and were provided access to a digital personalized nutrition tool for 9 weeks (N = 37; IBS only = 16, Crohn's disease and IBS = 9, and ulcerative colitis and IBS = 12).

RESULTS

Significant symptom improvement was seen for 81% of participants at study midpoint and persisted for 70% at end point, measured by the relevant symptom severity score (IBS symptom severity score, Patient Simple Clinical Colitis Activity Index, or Mobile Health Index for Crohn's disease). Clinically significant symptom improvement was observed in 78% of participants at midpoint and 62% at end point. Twenty-five participants (67.6%) achieved total symptomatic resolution by the end of study. Patient-reported quality of life improved for 89% of participants. Ninety-five percentage daily engagement, 95% retention, 89% adherence and 92% satisfaction with the program were reported.

DISCUSSION

Dietary elimination can improve symptoms and quality of life in patients with IBS and comorbid IBS/IBD. Digital technology can personalize dietary interventions and improve adherence. Randomized controlled trials are warranted.

Placebo response rates in randomized controlled trials for perianal Crohn's disease: A systematic review and meta-analysis

BACKGROUND AND AIMS

Perianal fistulizing disease is a common complication of Crohn's disease (CD), for which new therapies are urgently needed. To assist design of clinical trials for novel therapeutics, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to quantify placebo rates and identify factors influencing them in perianal CD.

METHODS

We searched MEDLINE, EMBASE and CENTRAL from inception to June 2021. Eligible studies were placebo-controlled trials of pharmacological interventions for perianal CD (pCD). Placebo fistula response and remission rates for induction and maintenance trials were extracted and pooled using a random-effects model. Mixed-effects meta-regression was used to evaluate the impact of patient and study-level characteristics on point estimates.

RESULTS

In 17 RCTs (13 induction, 5 maintenance) the pooled placebo fistula response and remission rate for induction trials was 25% (95% CI 17-36%) and 17% (95% CI 11-25%), respectively. For maintenance trials, the pooled placebo fistula response and remission rate was 23% (95% CI 17-32%) and 19% (95% CI 14-25%), respectively. Trials enrolling patients with less disease activity and a higher proportion with ileal predominant disease were associated with significantly higher placebo response rates. Trials originating in Europe (compared to North America), therapies requiring perianal injection and a longer timepoint to measure remission were associated with higher placebo remission rates.

CONCLUSIONS

Placebo response and remission rates in pCD trials are influenced by patient and disease-related factors, as well as the type of intervention being studied. These contemporary rates will inform trial design for novel therapeutics.

Analgesia in patients with adhesion-related chronic abdominal and pelvic pain after surgery: a systematic review

BACKGROUND AND OBJECTIVE

Adhesions are the most common cause of chronic abdominal pain after surgery. Surgical adhesiolysis can relieve symptoms in selected patients, but many require other treatments. The aim of this study is to evaluate analgesic treatments other than abdominal surgery in chronic pain related to adhesions.

DATABASE AND DATA TREATMENT

A search was conducted in PubMed, Embase, and Central. Studies with patients suffering from chronic postoperative pain related to adhesions and undergoing all types' analgesic treatment were included. The primary outcome was the number of patients who improved in pain at long-term follow-up (at least 1 year). Secondary outcomes included improvement in pain at 3 months follow-up, quality of life, and physical functioning.

RESULTS

Searches identified 3022 citations. Four studies were included, one trial, one cohort study, and two case reports. The primary outcome was not reported. In a small trial (n = 18) pregabalin tended to have a benefit over placebo improving pain at 3 months. In the cohort study, 17 patients with chronic pelvic pain underwent a trial of sacral nerve stimulation. Eight patients who responded positively received an implanted device for continuous modulation, reporting sustainable improvement during follow-up (range: 6-36 months). One case report described improved pain at 6 months with trans-abdominis plane stimulation. The second report described improvement of physical function with manual therapy at long-term follow-up.

CONCLUSIONS

Low level of evidence is available regarding analgesic treatments of chronic abdominal and pelvic pain related to adhesions. The benefit of pregabalin is doubtful; nerve modulation is promising in a selected group.HighlightsAdhesions are a frequent cause of chronic abdominal and pelvic pain after surgery.Many patients are not good candidates for surgery (Adhesiolysis) or have relapses of pain.There is an important knowledge gap regarding non-surgical analgesic treatment.Analgesia in adhesion-related chronic abdominal pain after surgery.

Circulating Pro-inflammatory Cytokines Do Not Explain Interindividual Variability in Visceral Sensitivity in Healthy Individuals

A role of the immune system in the pathophysiology of pain and hyperalgesia has received growing attention, especially in the context of visceral pain and the gut-brain axis. While acute experimental inflammation can induce visceral hyperalgesia as part of sickness behavior in healthy individuals, it remains unclear if normal plasma levels of circulating pro-inflammatory cytokines contribute to interindividual variability in visceral sensitivity. We herein compiled data from a tightly screened and well-characterized sample of healthy volunteers (N = 98) allowing us to assess associations between visceral sensitivity and gastrointestinal symptoms, and plasma concentrations of three selected pro-inflammatory cytokines (i.e., TNF-α, IL-6, and IL-8), along with cortisol and stress-related psychological variables. For analyses, we compared subgroups created to have distinct pro-inflammatory cytokine profiles, modelling healthy individuals at putative risk or resilience, respectively, for symptoms of the gut-brain axis, and compared them with respect to rectal sensory and pain thresholds and subclinical GI symptoms. Secondly, we computed multiple regression analyses to test if circulating pro-inflammatory markers predict visceral sensitivity in the whole sample. Despite pronounced subgroup differences in pro-inflammatory cytokine and cortisol concentrations, we observed no differences in measures of visceroception. In regression analyses, cytokines did not emerge as predictors. The pain threshold was predicted by emotional state and trait variables, especially state anxiety, together explaining 10.9% of the variance. These negative results do not support the hypothesis that systemic cytokine levels contribute to normal interindividual variability in visceroception in healthy individuals. Trajectories to visceral hyperalgesia as key marker in disorders of gut-brain interactions likely involve complex interactions of biological and psychological factors in keeping with a psychosocial model. Normal variations in systemic cytokines do not appear to constitute a vulnerability factor in otherwise healthy individuals, calling for prospective studies in at risk populations.

A therapeutic guide on pediatric irritable bowel syndrome and functional abdominal pain-not otherwise specified

Disorders of the gut-brain interaction negatively impact quality of life and carry a substantial socioeconomic burden. Irritable bowel syndrome (IBS) and functional abdominal pain-not otherwise specified (FAP-NOS) are common functional abdominal pain disorders in childhood. The pathophysiology is not fully understood, and high-quality intervention trials and international guidelines are missing. Therefore, the management of these disorders remains challenging. This review aims to provide an up-to-date overview of therapeutic possibilities for pediatric IBS or FAP-NOS and recommends management strategies. To prevent unnecessary referrals and extensive costs, it is fundamental to make a positive diagnosis of IBS or FAP-NOS in children with chronic abdominal pain with only minimal investigations. A tailor-made approach for each patient, based on the accompanying physical and psychological symptoms, is proposed to date.

CONCLUSION

Shared decision-making including non-pharmacological and pharmacological interventions should be considered and discussed with the family.

WHAT IS KNOWN

• Irritable bowel syndrome and functional abdominal pain-not otherwise specified are common in childhood. • Although the number of treatment options has grown recently, managing these disorders can be challenging and unsatisfactory, and no evidence-based international management guidelines are available.

WHAT IS NEW

• We suggest using a stepwise individualized approach to management, where after first-line management, both non-pharmacological and pharmacological interventions should be discussed.

Pelvic floor behavioral treatment for fecal incontinence and constipation in quiescent inflammatory bowel disease

BACKGROUND AND AIM

Refractory bowel symptoms in quiescent inflammatory bowel disease (IBD) are common but evidence for effective management is limited. We aimed to determine whether behavioral treatment, including pelvic floor muscle training, decreases the severity of functional bowel symptoms in patients with quiescent IBD. Secondary aims were to evaluate the treatment effect on quality of life, psychological well-being and pelvic floor muscle function.

METHODS

This prospective study included IBD patients in remission with persistent symptoms of fecal incontinence or constipation who received up to six sessions of behavioral treatment at monthly intervals. The primary outcome was patient-rated symptom improvement on a 7-point Likert scale (1 = substantially worse, 7 = substantially better). Secondary outcomes included validated symptom scores, quality-of-life, psychological measures, and transperineal ultrasound assessment of pelvic floor muscle activity.

RESULTS

Thirty-four patients (median age 38 years; 24 females; 18 ulcerative colitis, 13 Crohn's disease, 3 ileo-anal pouch) were included. Twenty-one of the 29 (72%) patients who completed treatment, or 21 of all 34 (62%) patients, reported moderate or substantial improvement (patient rating of 6 or 7). Symptom scores (p < .001), IBD-specific quality of life (p = .008) and illness perception scores (p = .003) significantly improved. General quality of life, and anxiety and depression scores, did not change significantly. Transperineal ultrasound pelvic floor measures did not correlate with patient-rating of symptom improvement.

CONCLUSION

Significant symptomatic improvement occurred in a majority of patients with quiescent IBD. Behavioral treatment should be considered for patients with quiescent IBD and ongoing functional bowel symptoms of fecal incontinence, fecal urgency, or constipation.

Clinical, Endoscopic, and Safety Placebo Rates in Induction and Maintenance Trials of Crohn's Disease: Meta-Analysis of Randomised Controlled Trials

BACKGROUND

Precision in estimating placebo rates is important for clinical trial design.

AIM

To quantify placebo rates across relevant endpoints in Crohn's disease [CD] trials and identify the factors influencing these rates in a contemporary meta-analysis.

METHODS

We searched MEDLINE, EMBASE, and CENTRAL from inception to March 2021. Eligible studies were placebo-controlled trials of pharmacological interventions for CD. Placebo response and remission rates for induction and maintenance trials were extracted and pooled by random-effects to quantify placebo rates across studies. Mixed-effects meta-regression was used to evaluate the effects of study-level characteristics on placebo rates.

RESULTS

In 125 studies [91 induction, 46 maintenance], placebo clinical remission and response rates for induction studies were 18% (95% confidence interval [CI] 16, 21%], and 32% [95% CI 29, 35%], respectively, and for maintenance studies were 28% [95% CI 23, 34%] and 30% [95% CI 24, 37%], respectively. Endoscopic remission and response rates in induction studies were 8% [95% CI 4, 18%] and 16% [95% CI 11, 23%], respectively. Trials enrolling patients with prior biologic exposure, longer disease duration, and higher CD activity index scores were associated with lower placebo clinical remission rates. Increased duration of follow-up, more follow-up visits, and a greater proportion of patients with colonic disease distribution were associated with higher clinical placebo rates.

CONCLUSIONS

Placebo remission and response rates in CD trials vary according to the phase of the trial, endpoint assessed, and induction or maintenance design. These contemporary estimates will help to inform future CD trial design.

Persistence of gastrointestinal symptoms in irritable bowel syndrome and ulcerative colitis: study protocol for a three-arm randomised controlled trial (SOMA.GUT-RCT)

INTRODUCTION

Ulcerative colitis (UC) and irritable bowel syndrome (IBS) are distressing chronic diseases associated with abdominal pain and altered bowel habits of unknown aetiology. Results from previous studies indicate that, across both diseases, increased levels of illness-related anxiety and dysfunctional symptom expectations contribute to symptom persistence. Thus, comparing both disorders with regard to common and disease-specific factors in the persistence and modification of gastrointestinal symptoms seems justified. Our primary hypothesis is that persistent gastrointestinal symptoms in UC and IBS can be improved by modifying dysfunctional symptom expectations and illness-related anxiety using expectation management strategies.

METHODS AND ANALYSIS

To assess the extent to which persistent somatic symptoms are modifiable in adult patients with UC and IBS, we will conduct an observer-blinded, three-arm randomised controlled trial. A total of 117 patients with UC and 117 patients with IBS will be randomised into three groups of equal size: targeted expectation management aiming to reduce illness-related anxiety and dysfunctional symptom expectations in addition to standard care (SC, intervention 1), non-specific supportive treatment in addition to SC (intervention 2) or SC only (control). Both active intervention groups will comprise three individual online consultation sessions and a booster session after 3 months. The primary outcome is baseline to postinterventional change in gastrointestinal symptom severity.

ETHICS AND DISSEMINATION

The study was approved by the Ethics Committee of the Hamburg Medical Association (2020-10198-BO-ff). The study will shed light onto the efficacy and mechanisms of action of a targeted expectation management intervention for persistent gastrointestinal symptoms in patients with UC and IBS. Furthermore, the detailed analysis of the complex biopsychosocial mechanisms will allow the further advancement of aetiological models and according evidence-based intervention strategies.

TRIAL REGISTRATION NUMBER

ISRCTN30800023.

[From gut feeling to visceral pain : Effects of negative expectations in the context of the gut-brain axis]

Disturbances of the gut-brain axis are characterized by complex dysfunctions on peripheral and central nervous system levels, which can contribute to visceral hypervigilance and hyperalgesia and imprint visceral pain. Numerous cognitive, emotional and psychoneurobiological factors are involved in visceral pain modulation, which in the psychosocial treatment concept can have a positive as well as a negative impact on the experience of visceral pain. Nocebo effects induced by negative expectations are of high clinical relevance in acute and especially in chronic visceral pain but the underlying mechanisms remain insufficiently understood. Verbal instructions, previous experiences and learning processes as well as emotional factors, such as fear and stress contribute to the development and maintenance of negative expectation effects. Targeted communication strategies, a sensitive use of information in the clarification and positive environmental context conditions can contribute to establishing an adequate expectation management and minimize negative expectation effects in the clinical practice. At the same time, translational research approaches are required to gain further insights into the mediators and moderators of negative expectation effects and to transfer these into clinical practice. In this way the treatment of patients with disorders of the gut-brain communication can be improved.

[Psychosocial Support for People with Ulcerative Colitis and Irritable Bowel Syndrome: A Feasibility Study on Need, Focus and Viability]

OBJECTIVES

Ulcerative colitis (UC) and irritable bowel syndrome (IBS) are associated with high somatic symptom burden, reduced quality of life, and increased psychological distress. The subjective burden, the wish of many patients, and the involvement of psychological processes in symptom perception justify the development of psychosocial support services. We aimed to evaluate need, content and feasibility of such an offer. We included patients with both UC and RDS in order to identify disease-specific and trans-diagnostic aspects for psychosocial interventions.

METHODS

We conducted telephone interviews with adult patients with UC or IBS using a standardized interview guide. We used numerical rating scales and open-ended questions to assess burden of and coping with the disease, disease-related expectations and anxiety, satisfaction with care, support and information needs, and preferences regarding support programs. We calculated descriptive metrics for quantitative variables as well as diagnosis-specific group comparisons. The answers to the open questions were summarised and counted in close accordance with the participants' statements.

RESULTS

N=35 patients (UC: n = 15; IBS: n=20) participated (age: M=40.80, SD=14.56; 71% female). In both groups, patients showed a medium level of disease burden, with higher rates for IBS. Both groups reported disease-related anxiety, with higher levels in patients with IBS. Disease-related expectations did not differ between groups. Patients with IBS showed low satisfaction with care and felt less informed about their disease than patients with UC. Both groups indicated a high motivation of participating in a psychological support program and named illness-related expectations and illness anxiety as important components of such.

DISCUSSION

The results confirm an increased need for psychosocial support and the relevance of disease-related expectations and anxiety for both diseases. Differences in symptom perception and care satisfaction indicate the importance of disease-specific elements in psychosocial therapy programs.

CONCLUSION

The results demonstrate the high need for psychosocial support of patients with UC and IBS and indicate the feasibility of a psychosocial therapy program.

The efficacy of vitamin D supplementation for irritable bowel syndrome: a systematic review with meta-analysis

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder involving gut-brain interactions with limited effective treatment options. Vitamin D deficiency is commonly observed in patients with IBS, but whether vitamin D supplementation ameliorates IBS is controversial in randomized controlled trials. The present systematic review and meta-analysis explored the efficacy of vitamin D supplementation in patients with IBS.

METHODS

We performed a systematic search of potentially relevant publications from PubMed, EMBASE, the Cochrane Central Register of Controlled Studies and the Web of Science up until January 2022. We assessed the weighted mean difference (WMD) and 95% confidence interval (95% CI) of the IBS severity scoring system (IBS-SSS), IBS quality of life (IBS-QoL) and IBS total score (IBS-TS) before and after vitamin D supplementation intervention.

RESULTS

We included four randomized, placebo-controlled trials involving 335 participants. The differences in IBS-SSS score between participants in the intervention group and the placebo group increased after intervention (WMD: -55.55, 95% CI: -70.22 to -40.87, I2 = 53.7%, after intervention; WMD: -3.17, 95% CI: -18.15 to 11.81, I2 = 0.0%, before intervention). Participants receiving vitamin D supplementation showed greater improvement in IBS-SSS after intervention than participants receiving placebo treatment (WMD: -84.21, 95% CI: -111.38 to -57.05, I2 = 73.2%; WMD: -28.29, 95% CI: -49.95 to -6.62, I2 = 46.6%, respectively). Vitamin D supplementation was also superior to placebo in IBS-QoL improvement (WMD: 14.98, 95% CI: 12.06 to 17.90, I2 = 0.0%; WMD: 6.55, 95% CI: -2.23 to 15.33, I2 = 82.7%, respectively). Sensitivity analyses revealed an unstable pooled effect on IBS-TS in participants receiving vitamin D supplementation. Therefore, we did not evaluate the efficacy of vitamin D intervention in IBS-TS.

CONCLUSIONS

This systematic review and meta-analysis suggested that vitamin D supplementation was superior to placebo for IBS treatment.

Budesonide Oral Suspension Improves Outcomes in Patients With Eosinophilic Esophagitis: Results from a Phase 3 Trial

BACKGROUND & AIMS

Eosinophilic esophagitis (EoE) is a chronic, immune-mediated disease for which there is currently no pharmacologic therapy approved by the US Food and Drug Administration.

METHODS

In this double-blind, placebo-controlled, phase 3 trial, patients 11-55 years of age with EoE and dysphagia were randomized 2:1 to receive budesonide oral suspension (BOS) 2.0 mg twice daily or placebo for 12 weeks at academic or community care practices. Co-primary endpoints were the proportion of stringent histologic responders (≤6 eosinophils/high-power field) or dysphagia symptom responders (≥30% reduction in Dysphagia Symptom Questionnaire [DSQ] score) over 12 weeks. Changes in DSQ score (key secondary endpoint) and EoE Endoscopic Reference Score (EREFS) (secondary endpoint) from baseline to week 12, and safety parameters were examined.

RESULTS

Overall, 318 patients (BOS, n = 213; placebo, n = 105) were randomized and received ≥1 dose of study treatment. More BOS-treated than placebo-treated patients achieved a stringent histologic response (53.1% vs 1.0%; Δ52% [95% confidence interval (CI), 43.3%-59.1%]; P < .001) or symptom response (52.6% vs 39.1%; Δ13% [95% CI, 1.6%-24.3%]; P = .024) over 12 weeks. BOS-treated patients also had greater improvements in least-squares mean DSQ scores and EREFS over 12 weeks than placebo-treated patients: DSQ, -13.0 (SEM 1.2) vs -9.1 (SEM 1.5) (Δ-3.9 [95% CI, -7.1 to -0.8]; P = .015); EREFS, -4.0 (SEM 0.3) vs -2.2 (SEM 0.4) (Δ-1.8 [95% CI, -2.6 to -1.1]; P < .001). BOS was well tolerated; most adverse events were mild or moderate in severity.

CONCLUSIONS

In patients with EoE, BOS 2.0 mg twice daily was superior to placebo in improving histologic, symptomatic, and endoscopic outcomes over 12 weeks. BOS 2.0 mg twice daily was well tolerated. ClinicalTrials.gov number: NCT02605837.

Patients' perceptions on non-specific effects of acupuncture: Qualitative comparison between responders and non-responders

BACKGROUND

Non-specific effect of acupuncture constitutes part of the overall effect generated via clinical encounter beyond needle insertion and stimulation. It is unclear how responders and non-responders of acupuncture experience non-specific effects differently. We aimed to compare their experiences in a nested qualitative study embedded in an acupuncture randomized trial on functional dyspepsia.

METHODS

Purposive sampling was used to capture experience of responders (n=15) and non-responders (n=15) to acupuncture via individual in-depth interviews. Design and analysis followed a framework analysis approach, with reference to an existing model on acupuncture non-specific effects. Themes emerging outside of this model were purposefully explored.

RESULTS

Responders had a more trusting relationship with acupuncturist in response to their expression of empathy. In turn they were more actively engaged in lifestyle modifications and dietary advice offered by acupuncturists. Non-responders were not satisfied with the level of reassurance regarding acupuncture safety. They were also expecting more peer support from fellow participants, regarded that as an empowerment process for initiating and sustaining lifestyle changes.

CONCLUSIONS

Our results highlighted key differences in acupuncture non-specific effect components experienced by responders and non-responders. Positive non-specific effects contributing to overall benefits could be enhanced by emphasizing on empathy expression from acupuncturists, trust-building, offering appropriate explanations on safety, and organizing patient support groups. Further research on the relative importance of each component is warranted.

Evaluating tolerability of resistant starch 2, alone and in combination with minimally fermented fibre for patients with irritable bowel syndrome: a pilot randomised controlled cross-over trial

Resistant starch 2 (RS2) may offer therapeutic value to irritable bowel syndrome (IBS) patients particularly in combination with minimally fermented fibre, but tolerability data are lacking. The present study evaluated the tolerability of RS2, sugarcane bagasse and their combination in IBS patients and healthy controls. Following baseline, participants consumed the fibres in escalating doses lasting 3 d each: RS2 (10, 15 and 20 g/d); sugarcane bagasse (5, 10 and 15 g/d); and their combination (20, 25 and 30 g/d). Gastrointestinal symptoms were assessed daily. Six IBS patients and five controls were recruited. No differences in overall symptoms from baseline were found across the fibre doses (IBS, P = 0⋅586; controls, P = 0⋅687). For IBS patients, all RS2 doses led to increased bloating. One IBS patient did not tolerate the low combination dose and another the high sugarcane bagasse dose. Supplementation of RS2 ≤ 20 g/d caused mild symptoms and was generally tolerated in IBS patients even when combined with minimally fermented fibre.

Positive Treatment Expectations Shape Perceived Medication Efficacy in a Translational Placebo Paradigm for the Gut-Brain Axis

Placebo research has established the pivotal role of treatment expectations in shaping symptom experience and patient-reported treatment outcomes. Perceived treatment efficacy constitutes a relevant yet understudied aspect, especially in the context of the gut-brain axis with visceral pain as key symptom. Using a clinically relevant experimental model of visceral pain, we elucidated effects of pre-treatment expectations on post-treatment perceived treatment efficacy as an indicator of treatment satisfaction in a translational placebo intervention. We implemented positive suggestions regarding intravenous treatment with a spasmolytic drug (in reality saline), herein applied in combination with two series of individually calibrated rectal distensions in healthy volunteers. The first series used distension pressures inducing pain (pain phase). In the second series, pressures were surreptitiously reduced, modeling pain relief (pain relief phase). Using visual analog scales (VAS), expected and perceived treatment efficacy were assessed, along with perceived pain intensity. Manipulation checks supported that the induction of positive pre-treatment expectations and the modeling of pain relief were successful. Generalized Linear Models (GLM) were implemented to assess the role of inter-individual variability in positive pre-treatment expectations in perceived treatment efficacy and pain perception. GLM indicated no association between pre-treatment expectations and perceived treatment efficacy or perceived pain for the pain phase. For the relief phase, pre-treatment expectations (p = 0.024) as well as efficacy ratings assessed after the preceding pain phase (p < 0.001) were significantly associated with treatment efficacy assessed after the relief phase, together explaining 54% of the variance in perceived treatment efficacy. The association between pre-treatment expectations and perceived pain approached significance (p = 0.057) in the relief phase. Our data from an experimental translational placebo intervention in visceral pain support that reported post-treatment medication efficacy is shaped by pre-treatment expectations. The observation that individuals with higher positive expectations reported less pain and higher treatment satisfaction after pain relief may provide first evidence that perceived symptom improvement may facilitate treatment satisfaction. The immediate experience of symptoms within a given psychosocial treatment context may dynamically change perceptions about treatment, with implications for treatment satisfaction, compliance and adherence of patients with conditions of the gut-brain axis.

Dietary fibres and IBS: translating functional characteristics to clinical value in the era of personalised medicine

Clinical guidelines in the use of fibre supplementation for patients with IBS provide one-size-fits-all advice, which has limited value. This narrative review addresses data and concepts around the functional characteristics of fibre and subsequent physiological responses induced in patients with IBS with a view to exploring the application of such knowledge to the precision use of fibre supplements. The key findings are that first, individual fibres elicit highly distinct physiological responses that are associated with their functional characteristics rather than solubility. Second, the current evidence has focused on the use of fibres as a monotherapy for IBS symptoms overall without attempting to exploit these functional characteristics to elicit specific, symptom-targeted effects, or to use fibre types as adjunctive therapies. Personalisation of fibre therapies can therefore target several therapeutic goals. Proposed goals include achieving normalisation of bowel habit, modulation of gut microbiota function towards health and correction of microbial effects of other dietary therapies. To put into perspective, bulking fibres that are minimally fermented can offer utility in modulating indices of bowel habit; slowly fermented fibres may enhance the activities of the gut microbiota; and the combination of both fibres may potentially offer both benefits while optimising the activities of the microbiota throughout the different regions of the colon. In conclusion, understanding the GI responses to specific fibres, particularly in relation to the physiology of the individual, will be the future for personalising fibre therapy for enhancing the personalised management of patients with IBS.

Meta-Analysis: Placebo Response and Its Determinants in Functional Dyspepsia

INTRODUCTION

Placebo response rates are relatively higher in clinical trials of disorders of brain-gut interaction. However, placebo response in functional dyspepsia (FD) has not been well described. Minimizing placebo response is important in drug development. We therefore conducted a meta-analysis to determine placebo response in trials for FD and to identify factors affecting placebo response rates.

METHODS

PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched to identify double-blinded randomized controlled trials (RCTs) comparing medication with placebo in patients with FD. Both symptom improvement and complete relief were considered as separate primary endpoints in the analysis. Proportions of placebo patients experiencing any symptom improvement or complete relief were calculated. Dropouts after randomization for any reason were assumed to represent treatment failure for data extraction and analysis. Placebo response was pooled by a random-effects model, and effects of trial characteristics on the magnitude of placebo response were evaluated.

RESULTS

In 58 eligible placebo-controlled RCTs of FD from 52 selected citations, 6,732 of 17,890 participants in all trials received placebo. Pooled placebo response rates for symptom improvement and complete relief were 44.3% and 15.6%, respectively. The placebo response rate was lower when improvements were assessed for ≥8 weeks. Trials assessing complete symptom relief showed lower placebo response rates even in trials for <8 weeks.

DISCUSSION

Our systematic review and meta-analysis showed that pooled placebo response rates in double-blinded RCTs of FD depended on efficacy criteria. Trials assessing complete symptom relief showed stable low placebo response rates in short-term trials.

Ayurvedic vs. Conventional Nutritional Therapy Including Low-FODMAP Diet for Patients With Irritable Bowel Syndrome-A Randomized Controlled Trial

Aims: To compare the effects of Ayurvedic and conventional nutritional therapy in patients with irritable bowel syndrome (IBS).

Methods: Sixty-nine patients with IBS were randomized to Ayurvedic (n = 35) or conventional nutritional therapy according to the recommendations of the German Nutrition Society including the low-FODMAP diet (n = 34). Study visits took place at baseline and after 1, 3, and 6 months. The primary outcome was IBS symptom severity (IBS-SSS) after 3 months; secondary outcomes included stress (CPSS), anxiety and depression (HADS), well-being (WHO-5) and IBS-specific quality of life (IBS-QOL). A repeated measures general linear model (GLM) for intent-to-treat-analyses was applied in this explorative study.

Results: After 3 months, estimated marginal means for IBS-SSS reductions were 123.8 [95% confidence interval (95% CI) = 92.8–154.9; p < 0.001] in the Ayurvedic and 72.7 (95% CI = 38.8–106.7; p < 0.001) in the conventional group. The IBS-SSS reduction was significantly higher in the Ayurveda group compared to the conventional therapy group (estimated marginal mean = 51.1; 95% CI = 3.8–98.5; p = 0.035) and clinically meaningful. Sixty-eight percentage of the variance in IBS-SSS reduction after 3 months can be explained by treatment, 6.5% by patients' expectations for their therapies and 23.4% by IBS-SSS at pre-intervention. Both therapies are equivalent in their contribution to the outcome variance. The higher the IBS-SSS score at pre-intervention and the larger the patients' expectations, the greater the IBS-SSS reduction. There were no significant group differences in any secondary outcome measures. No serious adverse events occurred in either group.

Conclusion: Patients with IBS seem to benefit significantly from Ayurvedic or conventional nutritional therapy. The results warrant further studies with longer-term follow-ups and larger sample sizes.

Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT03019861, identifier: NCT03019861.

The Relieving Effects of a Polyherb-Based Dietary Supplement ColonVita on Gastrointestinal Quality of Life Index (GIQLI) in Older Adults with Chronic Gastrointestinal Symptoms Are Influenced by Age and Cardiovascular Disease: A 12-Week Randomized Placebo-Controlled Trial

Chronic gastrointestinal symptoms (CGS) negatively affect the quality of life in about 15–30% of the population without effective drugs. Recent studies suggest that dietary supplement may improve CGS, but inconsistent results exist. The goal of this study is to evaluate the effect of a polyherbal-based supplement ColonVita on the gastrointestinal quality of life index (GIQLI) in 100 old adults with CGS (63.1 ± 9.6 years) who were randomly assigned to daily ColonVita or placebo tablets (n = 50/group) for 12 weeks in a double-blind, randomized controlled trial design. No significant fibrdifferences were found between ColonVita and placebo in the baseline total GIQLI score (101.12 ± 16.87 vs. 101.80 ± 16.48) (P > 0.05) or postintervention total GIQLI score (114.78 ± 9.62 vs. 111.74 ± 13.01) (P > 0.05). However, ColonVita significantly improved 16 scores of the 19 core GI symptoms compared with 10 items improved by placebo. The ColonVita group significantly improved the remission rate of 5 core GI symptoms compared to placebo and significantly improved the total GIQLI scores (118.09 ± 7.88 vs. 109.50 ± 16.71) (P < 0.05) and core GI symptom scores (64.61 ± 3.99 vs. 60.00 ± 8.65) (P < 0.05) in people ≥60 years of age (n = 49) but not in those under 60 y (n = 51). ColonVita significantly improved the total GIQLI scores and core GI symptom scores in people without cardiovascular diseases (CVD) (n = 56) (116.74 ± 9.38 vs. 110.10 ± 14.28) (P < 0.05) and (63.11 ± 4.53 vs. 59.93 ± 8.03) (P=0.07), respectively, but not in those with CVD (n = 44). Thus, ColonVita was beneficial for old adults with CGS, especially those ≥60 years of age and without CVD. Because a heterogenous pathogenesis of CGS-like irritable bowel syndrome (IBS) and inflammatory bowel disease (ISD) is differentially associated with CVD, different comorbidities may have influenced the outcomes of different trials that should be controlled in further studies.

Do Children With Functional Abdominal Pain Benefit More From a Pain-Specific Cognitive-Behavioral Intervention Than From an Unspecific Attention Control Intervention? Results of a Randomized Controlled Trial

INTRODUCTION

We aimed to compare the efficacy of cognitive-behavioral therapy (CBT) among children with functional abdominal pain with an attention control (AC), hypothesizing the superiority of CBT group intervention regarding pain intensity (primary outcome), pain duration and frequency (further primary outcomes), functional disability, and quality of life and coping strategies (key secondary outcomes).

METHODS

We conducted a prospective, multicenter, randomized controlled efficacy trial (RCT) with 4 time points (before intervention, after intervention, 3-month follow-up, and 12-month follow-up). One hundred twenty-seven children aged 7-12 years were randomized to either the CBT (n = 63; 55.6% girls) or the AC (n = 64; 57.8% girls).

RESULTS

Primary endpoint analysis of the logarithmized area under the pain intensity curve showed no significant difference between groups (mean reduction = 49.04%, 95% confidence interval [CI] -19.98%-78.36%). Treatment success rates were comparable (adjusted odds ratio = 0.53, 95% CI 0.21-1.34, number needed to treat = 16). However, time trend analyses over the course of 1 year revealed a significantly greater reduction in pain intensity (40.9%, 95% CI 2.7%-64.1%) and pain duration (43.6%, 95% CI 6.2%-66.1%) in the CBT compared with the AC, but not in pain frequency per day (1.2, 95% CI -2.7 to 5.2). In the long term, children in the CBT benefitted slightly more than those in the AC with respect to functional disability, quality of life, and coping strategies.

DISCUSSION

Both interventions were effective, which underlines the role of time and attention for treatment efficacy. However, in the longer term, CBT yielded more favorable results.

Pharmacologic Treatment in Functional Abdominal Pain Disorders in Children: A Systematic Review

CONTEXT

Functional abdominal pain disorders (FAPDs) are common in childhood, impacting quality of life and school attendance. There are several compounds available for the treatment of pediatric FAPDs, but their efficacy and safety are unclear because of a lack of head-to-head randomized controlled trials (RCTs).

OBJECTIVE

To systematically review the efficacy and safety of the pharmacologic treatments available for pediatric FAPDs.

DATA SOURCES

Electronic databases were searched from inception to February 2021.

STUDY SELECTION

RCTs or systematic reviews were included if the researchers investigated a study population of children (4-18 years) in whom FAPDs were treated with pharmacologic interventions and compared with placebo, no treatment, or any other agent.

DATA EXTRACTION

Two reviewers independently performed data extraction and assessed their quality. Any interresearcher disagreements in the assessments were resolved by a third investigator.

RESULTS

Seventeen articles representing 1197 children with an FAPD were included. Trials investigating antispasmodics, antidepressants, antibiotics, antihistaminic, antiemetic, histamine-2-receptor antagonist, 5-HT4-receptor agonist, melatonin, and buspirone were included. No studies were found on treatment with laxatives, antidiarrheals, analgesics, antimigraines, and serotonergics.

LIMITATIONS

The overall quality of evidence on the basis of the Grading of Recommendations, Assessment, Development and Evaluations system was very low to low.

CONCLUSIONS

On the basis of current evidence, it is not possible to recommend any specific pharmacologic agent for the treatment of pediatric FAPDs. However, agents such as antispasmodics or antidepressants can be discussed in daily practice because of their favorable treatment outcomes and the lack of important side effects. High-quality RCTs are necessary to provide adequate pharmacologic treatment. For future intervention trials, we recommend using homogenous outcome measures and instruments, a large sample size, and long-term follow-up.

The placebo response rate in pharmacological trials in patients with irritable bowel syndrome: a systematic review and meta-analysis

BACKGROUND

Clinical trials in irritable bowel syndrome are associated with high placebo response rates. We aimed to identify the magnitude of the placebo response and the contributing factors to this occurrence.

METHODS

We did a systematic review and meta-analysis with a search of MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials between April 1, 1959, and April 30, 2020. We included all randomised controlled trials that compared an active pharmacotherapeutic agent with placebo and had a dichotomous outcome of response to therapy (in terms of global improvement or improvement in abdominal pain) in adults (aged ≥18 years) with irritable bowel syndrome. Exclusion criteria were trials reporting on treatment satisfaction as a dichotomous outcome of response to therapy or clinician-reported outcomes and a treatment duration of less than 4 weeks. Our main outcome was identification of the magnitude of the pooled placebo response rate for the following endpoints: global improvement, abdominal pain, and US Food and Drug Administration (FDA) endpoints. We extracted information from published reports and pooled proportions through meta-analysis with random effects. The study was registered with PROSPERO, CRD42020170908.

FINDINGS

Of the 6863 publications identified, 70 articles describing 73 randomised controlled trials were included in our analysis. The pooled placebo response rate was 27·3% (95% CI 24·3-30·9) using the global improvement endpoint, 34·4% (31·2-37·8) using the abdominal pain endpoint, and 17·9% (15·2-21·0) using the composite FDA endpoint responder definition, all with substantial heterogeneity between the trials. Studies published before 2006, and those done in Europe, with a parallel design, a run-in period of 2 weeks or less, a dose schedule of three times a day or more, or a smaller sample size of the control group were significantly associated with an increased pooled placebo response rate.

INTERPRETATION

More than a quarter of patients with irritable bowel syndrome had a placebo response in terms of global improvement, with multiple associated moderators. We recommend future trials apply a run-in period of at least 2 weeks and dose once or twice a day to minimise the placebo response rate.

FUNDING

None.

Does the placebo effect on hot flashes depend on the placebo dose?

PURPOSE

To investigate the presence of a placebo dose-response effect in four randomized, double-blind, placebo-controlled, multi-dose hot flash clinical trials conducted at Mayo Clinic.

METHODS

Hot flash score, frequency, and hot flash-related distress for each placebo dose level were summarized at each time point by mean and standard deviation and changes from baseline were plotted to visualize a possible placebo dose-effect response. Furthermore, a meta-analysis was conducted for each endpoint in the highest and lowest dosage arms across the four trials.

RESULTS

Longitudinal plots of mean hot flash scores, frequencies, and hot flash-related distress scores in patients taking placebo in each study showed a decline in hot flash scores over time without any clinically meaningful differences between the lowest and highest dosage arms in each study. The meta-analysis for each endpoint in the highest and lowest dosage arms across the four trials revealed no clinically important differences either.

CONCLUSION

While the current study cannot rule out the existence of a placebo dose-response effect in multi-dose placebo-controlled trials in patients with hot flashes or other conditions, it suggests, along with the available data in the placebo literature, that, at least in well-conducted multi-dose clinical trials in which the placebo was used as control, such an effect, if it exists at all, should be very small. Therefore, pooling data from different placebo subgroups is unlikely to compromise the validity of comparisons between the combined placebo arms and each treatment arm.

Associative learning and extinction of conditioned threat predictors across sensory modalities

The formation and persistence of negative pain-related expectations by classical conditioning remain incompletely understood. We elucidated behavioural and neural correlates involved in the acquisition and extinction of negative expectations towards different threats across sensory modalities. In two complementary functional magnetic resonance imaging studies in healthy humans, differential conditioning paradigms combined interoceptive visceral pain with somatic pain (study 1) and aversive tone (study 2) as exteroceptive threats. Conditioned responses to interoceptive threat predictors were enhanced in both studies, consistently involving the insula and cingulate cortex. Interoceptive threats had a greater impact on extinction efficacy, resulting in disruption of ongoing extinction (study 1), and selective resurgence of interoceptive CS-US associations after complete extinction (study 2). In the face of multiple threats, we preferentially learn, store, and remember interoceptive danger signals. As key mediators of nocebo effects, conditioned responses may be particularly relevant to clinical conditions involving disturbed interoception and chronic visceral pain.

The Placebo and Nocebo Responses in Clinical Trials in Inflammatory Bowel Diseases

Placebo and nocebo responses are mostly discussed in clinical trials with functional bowel disorders. Much less has been investigated and is known in gastrointestinal diseases beyond irritable bowel syndrome (IBS), especially in inflammatory bowel diseases (IBD). For the purpose of this review, we screened the Journal of Interdisciplinary Placebo Studies (JIPS) database with approximately 4,500 genuine placebo research articles and identified nine meta-analyses covering more than 135 randomized and placebo-controlled trials (RCTs) with more than 10,000 patients with Crohn´s disease (CD) and another five meta-analyses with 150 RCTs and more than 10,000 patients with ulcerative colitis (UC). Only three discussed nocebo effects, especially in the context of clinical use of biosimilars to treat inflammation. The articles were critically analyzed with respect to the size of the placebo response in CD and UC, its effects on clinical improvement versus maintenance of remission, and mediators and moderators of the response identified. Finally, we discussed and compared the differences and similarities of the placebo responses in IBD and IBS and the nocebo effect in switching from biologics to biosimilars in IBD management.