Placebo responses and placebo effects in functional bowel disorders

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.

Placebo Responses and Placebo Effects in Functional Gastrointestinal Disorders

Much has been written about the placebo effects in functional gastrointestinal disorders (FGD), especially in irritable bowel syndrome (IBS), driven by the early hypothesis that in randomized controlled trials (RCTs) of IBS, the placebo effect might be specifically high and thus, corrupts the efficacy of novel drugs developed for this condition. This narrative review is based on a specific search method, a database (www.jips.online) developed since 2004 containing more than 4,500 papers (data papers, meta-analyses, systematic reviews, reviews) pertinent to the topic placebo effects/placebo response. Three central questions-deducted from the body of current literature-are addressed to explore the evidence behind this hypothesis: What is the size placebo effect in FGD, especially in IBS, and is it different from the placebo effect seen in other gastrointestinal disorders? Is the placebo effect in FGD different from other functional, non-intestinal disorders, e.g. in other pain syndromes? Is the placebo effect in FGD related to placebo effects seen in psychiatry, e.g. in depression, anxiety disorders, and alike? Following this discussion, a fourth question is raised as the result of the three: What are the consequences of this for future drug trials in FGD? In summary it is concluded that, contrary to common belief and discussion, the placebo effect seen in RCT in FGD is not specifically high and extraordinary as compared to other comparable (i.e. functional) disorders. It shares less than expected commonalities with the placebo effect in psychiatry, and very few predictors have yet been identified that determine its effect size, especially some that are driven by design features of the studies. Current practice of RCT in IBS seems to limit and control the placebo effect quite well, and future trial practice, e.g. head-to-head trial, still offers options to maintain this control, even in the absence of placebos used.

The effect of rikkunshito on gastrointestinal symptoms and gastric motor function: The first study in a Belgian functional dyspepsia population

BACKGROUND

Rikkunshito, a traditional Kampo medicine, has shown efficacy to treat functional dyspepsia (FD) in controlled trials in Japan. Its putative benefit for European patients and mechanism of action has not been established.

METHODS

This study examined the effect of rikkunshito on gastric motility and GI symptom perception in FD-PDS patients in a randomized, placebo-controlled, cross-over study. After a 2-week run-in period, patients received rikkunshito or matching placebo (2.5 g t.i.d.) for 4 weeks, separated by a 4-week washout period. Symptoms were assessed by the Leuven Postprandial Distress Scale (LPDS) diary throughout the study. At baseline and after both treatment arms, intragastric pressure (IGP) was measured to evaluate gastric accommodation and gastric motility. Simultaneously, GI symptoms were scored on a 100 mm visual analogue scale. Validated symptom questionnaires (PAGI-SYM, VSI, DSS, and PHQ) were completed each study visit.

KEY RESULTS

Twenty-three patients completed the study (33 ± 14 years, 22.7 ± 3.22 kg/m² ). Intragastric pressure was numerically, but not significantly, lower after rikkunshito compared with baseline and placebo (P = .14). No differences were found in gastric accommodation, nutrient volume tolerance, and symptoms assessed during IGP measurements. Early satiation and postprandial fullness (daily diary) decreased after rikkunshito compared with baseline (P < .041 for both). Placebo also improved most other symptoms assessed. No significant changes in VSI scores occurred. No adverse reactions occurred.

CONCLUSIONS

Rikkunshito did not alter gastric motility. Treatment with rikkunshito improved upper GI symptoms in FD patients but similarly high placebo effects were observed using the LPDS diary, PAGI-SYM, SF-NDI, and DSS scores. Rikkunshito was safe and well-tolerated.

Sacral nerve modulation for irritable bowel syndrome: A randomized, double-blinded, placebo-controlled crossover study

BACKGROUND

Irritable bowel syndrome (IBS) is among the most common gastrointestinal disorders, and a substantial proportion of patients have an insufficient response to treatment. In a single-blinded study, sacral nerve modulation (SNM) significantly reduced symptoms of IBS. The aim of the present double-blinded, randomized, placebo-controlled study was to evaluate the effect of SNM for IBS.

METHODS

We included patients with diarrhea-predominant or mixed IBS and a minimum baseline IBS-specific symptom score of 40 points (Gastrointestinal Symptom Rating Scale-IBS version). Patients underwent a 6-week period of SNM. In the first 4 weeks, the patients were randomized 1:1 to have the neurostimulator set subsensory or OFF for 2 weeks and then the opposite for another 2 weeks. Patients and investigators were blinded to settings. In the remaining 2 weeks, the stimulation was set suprasensory. IBS-specific symptoms and quality of life were assessed with validated questionnaires and bowel diaries.

KEY RESULTS

Twenty-one patients were randomized and eligible for analysis. The IBS-specific symptom score was reduced with borderline significance during stimulation (subsensory-OFF median change -1 (-26, 9), OFF-subsensory median change 8 (-11, 36); P = 0.0572). Pain was significantly reduced during stimulation (subsensory-OFF median change -1.5 (-4, 1), OFF-subsensory median change 1 (-4, 3); P = 0.0188), along with the number of daily bowel movements (subsensory-OFF median change 0 (-1.8, 0.2), OFF-subsensory median change 0.2 (-0.5, 1.1); P = 0.0373). The median placebo effect was 14% (0, 55).

CONCLUSION AND INFERENCES

Sacral nerve modulation for IBS seems promising but should be considered experimental until larger multicenter studies have been performed.

Optimising the performance and interpretation of small bowel capsule endoscopy

Small bowel capsule endoscopy has become a commonly used tool in the investigation of gastrointestinal symptoms and is now widely available in clinical practice. In contrast to conventional endoscopy, there is a lack of clear consensus on when competency is achieved or the way in which capsule endoscopy should be performed in order to maintain quality and clinical accuracy. Here we explore the evidence on the key factors that influence the quality of small bowel capsule endoscopy services.

The British Society of Gastroenterology/UK-PBC primary biliary cholangitis treatment and management guidelines

Primary biliary cholangitis (formerly known as primary biliary cirrhosis, PBC) is an autoimmune liver disease in which a cycle of immune mediated biliary epithelial cell injury, cholestasis and progressive fibrosis can culminate over time in an end-stage biliary cirrhosis. Both genetic and environmental influences are presumed relevant to disease initiation. PBC is most prevalent in women and those over the age of 50, but a spectrum of disease is recognised in adult patients globally; male sex, younger age at onset (<45) and advanced disease at presentation are baseline predictors of poorer outcome. As the disease is increasingly diagnosed through the combination of cholestatic serum liver tests and the presence of antimitochondrial antibodies, most presenting patients are not cirrhotic and the term cholangitis is more accurate. Disease course is frequently accompanied by symptoms that can be burdensome for patients, and management of patients with PBC must address, in a life-long manner, both disease progression and symptom burden. Licensed therapies include ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), alongside experimental new and re-purposed agents. Disease management focuses on initiation of UDCA for all patients and risk stratification based on baseline and on-treatment factors, including in particular the response to treatment. Those intolerant of treatment with UDCA or those with high-risk disease as evidenced by UDCA treatment failure (frequently reflected in trial and clinical practice as an alkaline phosphatase >1.67 × upper limit of normal and/or elevated bilirubin) should be considered for second-line therapy, of which OCA is the only currently licensed National Institute for Health and Care Excellence recommended agent. Follow-up of patients is life-long and must address treatment of the disease and management of associated symptoms.

Discharge of patients with an acute upper gastrointestinal bleed from the emergency department using an extended Glasgow-Blatchford Score

OBJECTIVE

To use an extended Glasgow-Blatchford Score (GBS) cut-off of ≤1 to aid discharge of patients presenting with acute upper gastrointestinal bleeding (AUGIB) from emergency departments.

BACKGROUND

The GBS accurately predicts the need for intervention and death in AUGIB, and a cut-off of 0 is recommended to identify patients for discharge without endoscopy. However, this cut-off is limited by identifying a low percentage of low-risk patients. Extension of the cut-off to ≤1 or ≤2 has been proposed to increase this proportion, but there is controversy as to the optimal cut-off and little data on performance in routine clinical practice.

METHODS

Dual-centre study in which patients with AUGIB and GBS ≤1 were discharged from the emergency department without endoscopy unless there was another reason for admission. Retrospective analysis of associated adverse outcome defined as a 30-day combined endpoint of blood transfusion, intervention or death.

RESULTS

569 patients presented with AUGIB from 2015 to 2018. 146 (25.7%) had a GBS ≤1 (70, GBS=0; 76, GBS=1). Of these, 103 (70.5%) were managed as outpatients, and none had an adverse outcome. GBS ≤1 had a negative predictive value=100% and the GBS had an area under receiver operator characteristic​​ (AUROC)=0.89 (95% CI 0.86 to 0.91) in predicting adverse outcomes. In 2008-2009, prior to risk scoring (n=432), 6.5% of patients presenting with AUGIB were discharged safely from the emergency department in comparison with 18.1% (p<0.001) in this cohort. A GBS cut-off ≤2 was associated with an adverse outcome in 8% of cases.

CONCLUSION

GBS of ≤1 is the optimal cut-off for the discharge of patients with an AUGIB from the emergency department.

Plausibility criteria for putative pathophysiological mechanisms in functional gastrointestinal disorders: a consensus of experts

BACKGROUND AND AIMS

The functional gastrointestinal disorders (FGIDs) are extremely common conditions associated with a considerable personal, social and health economic burden. Managing FGIDs in clinical practice is challenging because of the uncertainty of symptom-based diagnosis, the high frequency of overlap between these conditions and the limited efficacy of available therapies. It has often been argued that successful drug development and management of FGIDs requires knowledge of the underlying pathophysiology. Numerous and highly variable candidate pathophysiological mechanisms have been implicated in the generation of FGID symptoms, but there is no current consensus on how to best define the relevance of these disturbances.

METHODS

A group of international experts on FGIDs developed plausibility criteria that should be fulfilled by relevant pathophysiological mechanisms in FGIDs.

RESULTS

Five criteria are proposed: (1) the presence of the abnormality in a subset of patients, (2) temporal association between proposed mechanism and symptom(s), (3) correlation between the level of impairment of the mechanism and symptom(s), (4) induction of the symptom(s) by provoking the pathophysiological abnormality in healthy subjects and (5) treatment response by a therapy specifically correcting the underlying disorder or congruent natural history of symptoms and dysfunction in the absence of specific therapy. Based on strength of evidence for these five criteria according to the Grading of Recommendations Assessment, Development and Evaluation system, a plausibility score can be calculated for each mechanism.

CONCLUSION

Evaluation of the strength of evidence for candidate pathophysiological abnormalities fulfilling these five plausibility criteria will help to identify the most relevant mechanisms to target for novel diagnostic approaches and for the development of new therapies.

The role of diet in the management of irritable bowel syndrome: a focus on FODMAPs

Irritable bowel syndrome is a common condition that negatively impacts quality of life and results in significant health care expenditures. The vast majority of IBS patients associate their symptoms with eating. Numerous randomized, controlled trials suggest that restriction of dietary FODMAPs improves overall symptoms, abdominal pain, bloating and quality of life in more than half of IBS sufferers. There is emerging data which suggests that other diets (gluten free, guided elimination diets) might also be of benefit to IBS patients. Areas covered: Comprehensive literature review on dietary therapies available for IBS to date and exploration into individualized dietary therapy development based on diagnostic testing. Expert commentary: FODMAP elimination identifies IBS patients who are sensitive to FODMAPs. Responders should undergo a structured reintroduction of foods containing FODMAPs to determine a patient's sensitivities. This information can then be used to create a personalized, less restrictive low FODMAP diet. Future research should focus on the identification of other effective diet therapies focusing on supplementation of functional foods in addition to elimination and the development of biomarker-based diet treatment plans which identify the right treatment for the right patient.

The Rome IV versus Rome III criteria for heartburn diagnosis: A comparative study

BACKGROUND

The phenotypes of heartburn patients are heterogeneous.

OBJECTIVE

The objective of this study was to investigate the proportion of heartburn phenotypes in a Chinese population and to compare the Rome IV and III criteria for heartburn diagnosis.

METHODS

A retrospective study was performed among heartburn patients referred for upper endoscopy and esophageal function tests in a tertiary hospital. Their symptoms fulfilled Rome IV and III criteria.

RESULTS

A total of 233 patients were included. Fifty-nine patients (25%) were diagnosed with esophagitis, 96 (41%) with non-erosive reflux disease (NERD) and 78 (34%) with functional heartburn (FH) based on Rome III criteria. Approximately 70% of the Rome III NERD patients were changed based on Rome IV criteria, with 36 patients (15%) diagnosed with reflux hypersensitivity (RH) and 32 patients (14%) who didn't fulfill the criteria considered unclassified. The FH and RH patients showed higher esophagogastric junction-contractile integral (EGJ-CI) and less hiatal hernia than did Rome IV NERD patients. The unclassified had more hiatal hernias than the FH and RH (p < 0.05). The EGJ-CI was similar between Rome III NERD and FH cases.

CONCLUSION

The Rome IV criteria were stricter for heartburn diagnosis and superior in distinguishing NERD from functional disorders on motility patterns than Rome III.

Dietary therapies for functional bowel symptoms: Recent advances, challenges, and future directions

BACKGROUND

Functional gastrointestinal symptoms in irritable bowel syndrome (IBS) and quiescent inflammatory bowel disease (IBD) cause significant morbidity and a reduction in quality of life. Multiple dietary therapies are now available to treat these symptoms, but supporting evidence for many is limited. In addition to a further need for studies demonstrating efficacy and mechanism of action of dietary therapies, the risk of nutritional inadequacy, alterations to the microbiome and changes in quality of life are key concerns requiring elucidation. Identifying predictors of response to dietary therapy is an important goal as management could be tailored to the individual to target specific dietary components, and thereby reduce the level of dietary restriction necessary.

PURPOSE

This review discusses the available dietary therapies to treat symptoms in patients with IBS and patients with quiescent IBD suffering from IBS symptoms, with the aim to understand where current dietary evidence lies and how to move forward in dietary research in this field.

A non-interventional, observational study of a fixed combination of pepsin and amino acid hydrochloride in patients with functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a gastrointestinal disorder characterized by recurrent and diverse symptoms and pathophysiology that remains unexplained following routine clinical investigation. Enzynorm®f is a pharmaceutical preparation comprising fixed amounts of pepsin of biological origin and organically bound acid in the form of amino acid hydrochloride. It is traditionally used as a mild agent to support gastric function and to stimulate the stomach's proteolytic activities in FD.

METHODS

In a non-interventional, observational, post-marketing surveillance study, patients with an established diagnosis of FD were treated with a fixed combination of pepsin and amino acid hydrochloride taken as tablets three times daily for 6 weeks. The primary objective of this study was to assess the change in symptoms using the validated Gastrointestinal Symptom Score (GIS©). Secondary objectives included patients' assessment of their gastrointestinal symptoms as well as treatment safety and tolerability.

RESULTS

A total of 97 patients (mean age 58.4 ± 13.9 years; 63.2% females) were included in the study, with 72 data having GIS© score data at baseline and at 6 weeks, and 34 also at 3 weeks. The overall GIS© sum score decreased by 4.1 (p < 0.0001) from 11.6 (±4.8) at baseline to 7.4 (± 4.6) reflecting an improvement of clinical symptomatology after 6 weeks of treatment. In a subgroup of 70 patients who had FD meeting the Rome III criteria a GIS© score reduction of ≥50% was observed after 3 weeks treatment in 24% and in 30.8% after 6 weeks. Adverse events were mostly gastrointestinal in nature and consistent with the underlying disease; no unexpected adverse reactions were reported. Twenty-seven patients discontinued the study, mostly because of gastrointestinal symptoms.

CONCLUSION

The results of this study support the efficacy of a fixed combination of pepsin and amino acid hydrochloride for the treatment of patients with FD and also suggest good to moderate treatment tolerability. These findings should be further explored in a randomised, placebo-controlled clinical trial.

CLINICAL TRIAL REGISTRATION

This study has been retrospectively registered in the ClinicalTrials.gov registry, trial identifier NCT03076411 .

Systematic review: quality of trials on the symptomatic effects of the low FODMAP diet for irritable bowel syndrome

BACKGROUND

The low Fermentable Oligo-, Di- Monosaccharides, and Polyoles (FODMAP) diet is a new treatment option for irritable bowel syndrome (IBS). Experts refer to the diet as supported by high level of evidence, but an evaluation of the quality of trials is lacking.

AIM

To provide a systematic review of the quality of trials on the symptomatic effects of the low FODMAP diet for IBS.

METHODS

Pubmed and EMBASE were searched for randomised controlled trials (RCTs) reporting effect of the low FODMAP diet on IBS symptoms. The quality of trials was evaluated by estimating risk of bias and assessing trial methodology.

RESULTS

Nine RCTs were eligible, including 542 patients. The intervention period was from 2 days to 6 weeks and one trial included a 6-month follow-up. Three trials intervened by providing meals, controlling with a diet high in FODMAP content. In six trials, the intervention was instruction by a dietician and a variety of control interventions were used, all with limited established efficacy. Domains with a high risk of bias were identified for all the trials. High risk of bias dominated domains regarding blinding, with only one trial double-blinded.

CONCLUSIONS

The RCTs on the low FODMAP diet are characterized by high risk of bias. The diet has not been studied in a randomised, controlled setting for more than 6 weeks and trials examining the effect of the important reintroduction period are lacking. There is a risk that the symptomatic effects reported in the trials are driven primarily by a placebo response.

Electroacupuncture for patients with diarrhea-predominant irritable bowel syndrome or functional diarrhea: A randomized controlled trial

Diarrhea-predominant irritable bowel syndrome (IBS-D) and functional diarrhea (FD) are highly prevalent, and the effectiveness of acupuncture for managing IBS-D and FD is still unknown.The aim of this study was to compare the effectiveness of electroacupuncture with loperamide.It was a prospective, randomized, parallel group controlled trial.A total of 448 participants were randomly assigned to He electroacupuncture group (n = 113), Shu-Mu electroacupuncture group (n = 111), He-Shu-Mu electroacupuncture group (n = 112), or loperamide group (n = 112). Participants in the 3 acupuncture groups received 16 sessions of electroacupuncture during a 4-week treatment phase, whereas participants in the loperamide group received oral loperamide 2 mg thrice daily. The primary outcome was the change from baseline in stool frequency at the end of the 4-weeks treatment. The secondary outcomes were the Bristol scale, the MOS 36-item short form health survey (SF-36), the weekly average number of days with normal defecations and the proportion of adverse events.Stool frequency was significantly reduced at the end of the 4-week treatment in the 4 groups (mean change from baseline, 5.35 times/week). No significant difference was found between the 3 electroacupuncture groups and the loperamide group in the primary outcome (He vs. loperamide group [mean difference 0.6, 95% CI, -1.2 to 2.4]; Shu-Mu vs. loperamide group [0.4, 95% CI, -1.4 to 2.3]; He-Shu-Mu vs. loperamide group [0.0, 95% CI, -1.8 to 1.8]). Both electroacupuncture and loperamide significantly improved the mean score of Bristol scale and increased the weekly average number of days with normal defecations and the mean scores of SF-36; they were equivalent in these outcomes. However, the participants in electroacupuncture groups did not report fewer adverse events than those in the loperamide group. Similar results were found in a subgroup analysis of separating patients with IBS-D and FD patients.Electroacupuncture is equivalent to loperamide for reducing stool frequency in IBS-D and FD patients. Further studies on cost effectiveness of acupuncture are warranted.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

The placebo effect has often been considered a nuisance in basic and particularly clinical research. This view has gradually changed in recent years due to deeper insight into the neuro-bio-behavioral mechanisms steering both the placebo and nocebo responses, the evil twin of placebo. For the neuroscientist, placebo and nocebo responses have evolved as indispensable tools to understand brain mechanisms that link cognitive and emotional factors with symptom perception as well as peripheral physiologic systems and end organ functioning. For the clinical investigator, better understanding of the mechanisms driving placebo and nocebo responses allow the control of these responses and thereby help to more precisely define the efficacy of a specific pharmacological intervention. Finally, in the clinical context, the systematic exploitation of these mechanisms will help to maximize placebo responses and minimize nocebo responses for the patient's benefit. In this review, we summarize and critically examine the neuro-bio-behavioral mechanisms underlying placebo and nocebo responses that are currently known in terms of different diseases and physiologic systems. We subsequently elaborate on the consequences of this knowledge for pharmacological treatments of patients and the implications for pharmacological research, the training of healthcare professionals, and for the health care system and future research strategies on placebo and nocebo responses.

Diagnosis and Management of Functional Heartburn

Heartburn is among the most common gastrointestinal symptoms presenting to both generalist physicians and gastroenterologists. Heartburn that does not respond to traditional acid suppression is a diagnostic and therapeutic dilemma. In the era of high utilization of proton pump inhibitors, a substantial proportion of patients presenting to the gastroenterologist with chronic symptoms of heartburn do not have a reflux-mediated disease. Subjects without objective evidence of reflux as a cause of their symptoms have "functional heartburn". The diagnostic role of endoscopy, reflux and motility testing in functional heartburn (FH) patients is discussed. Lifestyle modifications, pharmacological interventions, and alternative therapies for FH are also presented. Recognition of patients with FH allows earlier assignment of these patients to different treatment algorithms, which may allow greater likelihood of success of treatment, diminished resource utilization and improved quality of life. Further data on this large and understudied group of patients is necessary to allow improvement in treatment algorithms and a more evidence-based approach to care of these patients.

Percutaneous tibial nerve stimulation versus sham electrical stimulation for the treatment of faecal incontinence in adults (CONFIDeNT): a double-blind, multicentre, pragmatic, parallel-group, randomised controlled trial

BACKGROUND

Percutaneous tibial nerve stimulation (PTNS) is a new ambulatory therapy for faecal incontinence. Data from case series suggest it has beneficial outcomes in 50-80% patients; however its effectiveness against sham electrical stimulation has not been investigated. We therefore aimed to assess the short-term efficacy of PTNS against sham electrical stimulation in adults with faecal incontinence.

METHODS

We did a double-blind, multicentre, pragmatic, parallel-group, randomised controlled trial (CONtrol of Faecal Incontinence using Distal NeuromodulaTion [CONFIDeNT]) in 17 specialist hospital units in the UK that had the skills to manage patients with faecal incontinence. Eligible participants aged 18 years or older with substantial faecal incontinence for whom conservative treatments (such as dietary changes and pelvic floor exercises) had not worked, were randomly assigned (1:1) to receive either PTNS (via the Urgent PC neuromodulation system) or sham stimulation (via a transcutaneous electrical nerve stimulation machine to the lateral forefoot) once per week for 12 weeks. Randomisation was done with permuted block sizes of two, four, and six, and was stratified by sex and then by centre for women. Patients and outcome assessors were both masked to treatment allocation for the 14-week duration of the trial (but investigators giving the treatment were not masked). The primary outcome was a clinical response to treatment, which we defined as a 50% or greater reduction in episodes of faecal incontinence per week. We assessed this outcome after 12 treatment sessions, using data from patients' bowel diaries. Analysis was by intention to treat, and missing data were multiply imputed. This trial is registered with the ISRCTN registry, number 88559475, and is closed to new participants.

FINDINGS

Between Jan 23, 2012, and Oct 31, 2013, we randomly assigned 227 eligible patients (of 373 screened) to receive either PTNS (n=115) or sham stimulation (n=112). 12 patients withdrew from the trial: seven from the PTNS group and five from the sham group (mainly because they could not commit to receiving treatment every week). Two patients (one in each group) withdrew because of an adverse event that was unrelated to treatment (exacerbation of fibromyalgia and rectal bleeding). 39 (38%) of 103 patients with full data from bowel diaries in the PTNS group had a 50% or greater reduction in the number of episodes of faecal incontinence per week compared with 32 (31%) of 102 patients in the sham group (adjusted odds ratio 1·28, 95% CI 0·72-2·28; p=0·396). No serious adverse events related to treatment were reported in the trial. Seven mild, related adverse events were reported in each treatment group, mainly pain at the needle site (four in PTNS, three in sham).

INTERPRETATION

PTNS given for 12 weeks did not confer significant clinical benefit over sham electrical stimulation in the treatment of adults with faecal incontinence. Further studies are warranted to determine its efficacy in the long term, and in patient subgroups (ie, those with urgency).

FUNDING

National Institute for Health Research.

Placebo effects and their determinants in gastrointestinal disorders

Placebo effects in clinical trials have sparked an interest in the placebo phenomenon, both in randomized controlled trials (RCTs) and in experimental gastroenterology. RCTs have demonstrated similar short-term and long-term placebo response rates in gastrointestinal compared to other medical diagnoses. Most mediators and moderators of placebo effects in gastrointestinal diseases are also of similar type and size to other medical diagnoses and not specific for gastrointestinal diagnoses. Other characteristics such as an increase in the placebo response over time and the placebo-enhancing effects of unbalanced randomization were not seen, at least in IBS. Experimental placebo and nocebo studies underscore the 'power' of expectancies and conditioning processes in shaping gastrointestinal symptoms not only at the level of self-reports, but also within the brain and along the brain-gut axis. Brain imaging studies have redressed earlier criticism that placebo effects might merely reflect a response bias. These findings raise hope that sophisticated trials and experiments designed to boost positive expectations and minimize negative expectations could pave the way for a practical and ethically sound use of placebo knowledge in daily practice. Rather than focusing on a 'personalized' choice of drugs based on biomarkers or genes, it might be the doctor-patient communication that needs to be tailored.

Randomised clinical trial: gut microbiome biomarkers are associated with clinical response to a low FODMAP diet in children with the irritable bowel syndrome

BACKGROUND

A low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet can ameliorate symptoms in adult irritable bowel syndrome (IBS) within 48 h.

AIM

To determine the efficacy of a low FODMAP diet in childhood IBS and whether gut microbial composition and/or metabolic capacity are associated with its efficacy.

METHODS

In a double-blind, crossover trial, children with Rome III IBS completed a 1-week baseline period. They then were randomised to a low FODMAP diet or typical American childhood diet (TACD), followed by a 5-day washout period before crossing over to the other diet. GI symptoms were assessed with abdominal pain frequency being the primary outcome. Baseline gut microbial composition (16S rRNA sequencing) and metabolic capacity (PICRUSt) were determined. Metagenomic biomarker discovery (LEfSe) compared Responders (≥50% decrease in abdominal pain frequency on low FODMAP diet only) vs. Nonresponders (no improvement during either intervention).

RESULTS

Thirty-three children completed the study. Less abdominal pain occurred during the low FODMAP diet vs. TACD [1.1 ± 0.2 (SEM) episodes/day vs. 1.7 ± 0.4, P < 0.05]. Compared to baseline (1.4 ± 0.2), children had fewer daily abdominal pain episodes during the low FODMAP diet (P < 0.01) but more episodes during the TACD (P < 0.01). Responders were enriched at baseline in taxa with known greater saccharolytic metabolic capacity (e.g. Bacteroides, Ruminococcaceae, Faecalibacterium prausnitzii) and three Kyoto Encyclopedia of Genes and Genomes orthologues, of which two relate to carbohydrate metabolism.

CONCLUSIONS

In childhood IBS, a low FODMAP diet decreases abdominal pain frequency. Gut microbiome biomarkers may be associated with low FODMAP diet efficacy. ClinicalTrials.gov identifier: NCT01339117.

Effect of administering a multi-species probiotic mixture on the changes in fecal microbiota and symptoms of irritable bowel syndrome: a randomized, double-blind, placebo-controlled trial

We assessed the effect of multi-species probiotic mixture on the changes in fecal microbiota and irritable bowel syndrome (IBS) symptoms. Eighty-one IBS patients were randomly assigned to receive either probiotic mixture (n = 39; containing Lactobacillus acidophilus, L. rhamnosus, Bifidobacterium breve, B. actis, B. longum, and Streptococcus thermophilus) or placebo (n = 42) for 4 weeks. A questionnaire regarding general symptom relief was administered. The change in total symptom scores (sum of 10 IBS symptoms) and subtotal scores in 4 domains (pain, constipation, diarrhea, and bloating/gas) were evaluated. The change in fecal flora was determined by quantitative real-time PCR. The concentration of probiotic strains significantly increased after ingestion in probiotics group (B. bifidum, p = 0.043; B. lactis, p<0.001; L. acidophilus, p = 0.016; L. rhamnosus, p<0.001). The proportion of patients with adequate symptom relief was higher in probiotics group than in placebo group (74.4% vs 61.9%, p = 0.230). The decrease in total symptom score over time was not significantly different between the groups (p = 0.703). Among subtotal scores of 4 IBS symptom domains, the time effect was significantly different for diarrhea-symptom score between the groups (p = 0.017). A 4-week administration of multi-species probiotic mixture significantly increased the fecal concentration of most probiotic strains and improved diarrhea-symptom scores in IBS patients.

Placebo eff ects in psychiatry: mediators and moderators

A strong placebo response in psychiatric disorders has been noted for the past 50 years and various attempts have been made to identify predictors of it, by use of meta-analyses of randomised controlled trials and laboratory studies. We reviewed 31 meta-analyses and systematic reviews of more than 500 randomised placebo-controlled trials across psychiatry (depression, schizophrenia, mania, attention-deficit hyperactivity disorder, autism, psychosis, binge-eating disorder, and addiction) for factors identified to be associated with increased placebo response. Of 20 factors discussed, only three were often linked to high placebo responses: low baseline severity of symptoms, more recent trials, and unbalanced randomisation (more patients randomly assigned to drug than placebo). Randomised controlled trials in non-drug therapy have not added further predictors, and laboratory studies with psychological, brain, and genetic approaches have not been successful in identifying predictors of placebo responses. This comprehensive Review suggests that predictors of the placebo response are still to be discovered, the response probably has more than one mediator, and that different and distinct moderators are probably what cause the placebo response within psychiatry and beyond.

Are all placebo respondents non-smokers?

BACKGROUND

In smoking cessation trials, placebo response rates are reported to be rather low, and they are lowest when compared to the placebo response rates of treatment of other addictions. We hypothesized that high placebo response rates in trials outside of cessation treatment may predict low participation of smokers, and that non-smoking may be a behavioral marker of the placebo response.

METHODS

We re-analyzed raw data from a randomized controlled drug trial in functional dyspepsia (n=315) for the number of smokers and non-smokers in both treatment arms (drug, placebo) and varied the responder definition in a sensitivity analysis.

RESULTS

An equal number of smokers and non-smokers were assigned to drug and placebo. With the pre-defined responder definition (40% symptom improvement of a patient-reported outcome scale), 3% of placebo responders were smokers, but around 20% of patients among the placebo non-responder, and the drug responders and non-responders. With a more restrictive response definition (50% improvement) none of the placebo responders (n=29) was a smoker while the percentage of smokers remained similar in all other groups (p<.001). Age and gender did not affect this distribution.

CONCLUSION

Non-smoking behavior may be association with higher placebo response rates and may indicate a biomarker for reward sensitivity of the nicotine-dopamine pathway. Common genotypes may underlie both behaviors.

How positive and negative expectations shape the experience of visceral pain

Knowledge from placebo and nocebo research aimed at elucidating the role of treatment expectations and learning experiences in shaping the response to visceral pain fills an important research gap. First, chronic abdominal pain, such as in irritable bowel syndrome (IBS), is highly prevalent, with detrimental individual and socioeconomic impact and limited effective treatment options. At the same time, IBS patients show high placebo response rates in clinical trials and benefit from placebo interventions. Second, psychological factors including emotions and cognitions in the context of visceral pain have been implicated in the pathophysiology of IBS and other conditions characterized by medically unexplained somatic symptoms. Hence, the study of nocebo and placebo effects in visceral pain constitutes a model to assess the contribution of psychological factors. Herein, the clinical relevance of visceral pain is introduced with a focus on IBS as a bio-psycho-social disorder, followed by a review of existing clinical and experimental work on placebo and nocebo effects in IBS and in clinically relevant visceral pain models. Finally, emerging research trends are highlighted along with an outlook regarding goals for ongoing and future research.

Traditional and innovative experimental and clinical trial designs and their advantages and pitfalls

Many study designs and design variants have been developed in the past to either overcome or enhance drug-placebo differences in clinical trials or to identify and characterize placebo responders in experimental studies. They share many commonalities as well as differences that are discussed here: the role of deception and ethical restrictions, habituation effects and the control of the natural course of disease, assay sensitivity testing and effective blinding, acceptability and motivation of patients and volunteers, and the development of individualized medicine. These are fostered by two opposite strategies: utilizing the beneficial aspects of the placebo response-and avoiding its negative counterpart, the nocebo effect-in medical routine for the benefit of patients, and minimizing-by controlling-the negative aspects of the placebo effect during drug development.

A traditional herbal formula, Hyangsa-Pyeongwi san (HPS), improves quality of life (QoL) of the patient with functional dyspepsia (FD): randomized double-blinded controlled trial

ETHNOPHARMACOLOGICAL RELEVANCE

Hyangaa-Pyeongwi san is the most well known description in Traditional Chinese Medicine for treating functional gastrointestinal disorders. Functional dyspepsia (FD) is a main concern of intimidating quality of life (QoL) in recent days. Although many medicines have been developed to improve FD symptoms as well as QoL, there are no potential drugs and treatments for FD. The aim of this study is to investigate the effects of Hyangaa-Pyeongwi san (HPS) on QoL of patients with FD.

METHODS

This study was designed as a randomized, double blinded, placebo controlled, and parallel group trial. Participants received either placebo or HPS (9.68g of HPS at once, three times daily) for 4-weeks, and the efficacy evaluations were performed by assessing the Nepean Dyspepsia Index (NDI) and functional dyspepsia-quality of life (FD-QoL) at 0-, 4- and 8-weeks.

RESULTS

Total of 170 patients participated and were randomly allocated into placebo or HPS groups. Total symptom score of NDI decreased after 4-weeks trial in both groups (p>0.05). HPS significantly improved QoL scores, especially in the area of 'interference and eat/drink' in NDI (p=0.0031) as well as 'liveliness status', 'role-functioning status', and total score in FD-QoL (p=0.026 for liveliness status and p=0.035 for role-functioning status). This significant improvement of FD-QoL had lasted for 4-weeks.

CONCLUSION

HPS treatment is markedly effective in improving QoL in patients with FD. Moreover, we observed that this improvement had lasted for 4 weeks after finishing the trial through the follow-up study.

A survey of pharmacological and nonpharmacological treatment of functional gastrointestinal disorders

BACKGROUND

Treatment of functional gastrointestinal disorders (FGIDs) is based on symptoms relieve by conventional drugs, but increasingly complementary and alternative medicine (CAM) is used.

OBJECTIVE

This survey aimed to investigate the current treatments used by FGIDs patients.

METHODS

A total of 25 Italian gastroenterologists interviewed outpatients on gastrointestinal symptoms and treatments (pharmacological, CAM, diet/dietary supplements) used during the last year to relieve FGIDs. Consecutive adults with FGIDs according to Rome III were included.

RESULTS

Of the 199 patients, 81% used conventional drugs, 64.3% diet/dietary supplements, and 48.7% CAM. Conventional drugs, diet/dietary supplements, or CAM as exclusive treatment were used by 24.6, 6, and 2.5% of patients, respectively. Two-thirds used more than one treatment: 34.7% conventional drugs, CAM, and diet/dietary supplements, 17.1% conventional drugs and diet/dietary supplements, 10.1% diet and CAM, and 5% conventional drugs and CAM. Benefits and adverse effects were similar for conventional drugs and nonpharmacological treatments. Males (OR 2.4) without lower GI symptoms (OR 5.4) used more frequently exclusive pharmacological treatment of FGIDs.

CONCLUSIONS

Conventional drugs are the preferred treatment for FGID. CAM and dietary modifications are more likely used as an adjunct to rather than instead of conventional drugs. Adverse effects occurred in all treatments.

Effects of improved patient participation in primary care on health-related outcomes: a systematic review

BACKGROUND

In primary care, many consultations address symptom-based complaints. Recovery from these complaints seldom exceeds placebo effects. Patient participation, because of its supposed effects on trust and patient expectancies, is assumed to benefit patients' recovery. While the idea is theoretically promising, it is still unclear what the effects of increased patient participation are on patient outcomes. Aim. To review the effects of controlled intervention studies aiming to improve patient participation in face-to-face primary care consultations on patient-oriented and/or disease-oriented outcomes.

METHODS

This study is a systematic review. A systematic search was undertaken for randomized controlled trials designed to measure the effects of interventions that aimed to improve adult patients' participation in primary care visits. The CINAHL, Cochrane, EMBASE, PsycINFO and PubMed databases were searched.

RESULTS

Seven different trials fulfilled the inclusion criteria. Three of the studies were related to symptom-based complaints. Five studies measured patient-oriented outcomes, the primary outcome of interest for this review. All studies suffered from substantial bias. Studies varied widely in their aims, types of complaints/diseases, strength of the interventions and their outcomes. The effects on patient-oriented outcomes and disease-oriented outcomes were ambiguous.

CONCLUSION

Little research has been performed on health outcomes of interventions aiming to increase patient participation in general practice visits among patients suffering from symptom-based complaints. The results still are non-conclusive. The quality of the trials has been weak, possibly due to the complexity of the concept. This weak quality may explain the lack of conclusive results. Proposals for future research designs are offered.

Placebo effects in children: a review

Of more than 155,000 PubMed citations found with the search term "placebo," only ~9,000 (5.8%) included the terms "children" or "adolescents." When all these papers were screened, only ~2,000 of them investigated the placebo effect per se, and of those, only ~50 (2.5%) discussed the placebo effect in children and adolescents. In this narrative review, we explore four aspects of the placebo response in children and adolescents: (i) the legal and ethical limitations and restrictions for the inclusion of children in clinical trials as well as in experimental (placebo) research that may explain the poor knowledge base; (ii) the question of whether or not the placebo effect is larger in children and adolescents as compared with adults; (iii) whether the mechanisms underlying the placebo effect are similar between children and adults; and (iv) whether mediators and moderators of the placebo effect are comparable between children and adults. We finally discuss some of the consequences from the current placebo research in adults that may affect both experimental and clinical research in children and adolescents.

Perceived treatment group affects behavioral and neural responses to visceral pain in a deceptive placebo study

BACKGROUND

To assess effects of perceived treatment (i.e. drug vs placebo) on behavioral and neural responses to rectal pain stimuli delivered in a deceptive placebo condition.

METHODS

This fMRI study analyzed the behavioral and neural responses during expectation-mediated placebo analgesia in a rectal pain model. In N = 36 healthy subjects, the blood oxygen level-dependent (BOLD) response during cued anticipation and painful stimulation was measured after participants were informed that they had a 50% chance of receiving either a potent analgesic drug or an inert substance (i.e., double-blind administration). In reality, all received placebo. We compared responses in subjects who retrospectively indicated that they received the drug and those who believed to have received placebo.

KEY RESULTS

55.6% (N = 20) of subjects believed that they had received a placebo, whereas 36.1% (N = 13) believed that they had received a potent analgesic drug. Subjects who were uncertain (8.3%, N = 3) were excluded. Rectal pain-induced discomfort was significantly lower in the perceived drug treatment group (P < 0.05), along with significantly reduced activation of the insular, the posterior and anterior cingulate cortices during pain anticipation, and of the anterior cingulate cortex during pain (all P < 0.05 in regions-of-interest analyses).

CONCLUSIONS & INFERENCES

Perceived treatment constitutes an important aspect in placebo analgesia. A more refined understanding of individual treatment expectations and perceived treatment allocation has multiple implications for the design and interpretation of clinical trials and experimental studies on placebo and nocebo effects.