Mixture model analysis identifies irritable bowel syndrome subgroups characterised by specific profiles of gastrointestinal, extraintestinal somatic and psychological symptoms

LACE-UP: An ensemble machine-learning method for health subtype classification on multidimensional binary data

Disease and behavior subtype identification is of significant interest in biomedical research. However, in many settings, subtype discovery is limited by a lack of robust statistical clustering methods appropriate for binary data. Here, we introduce LACE-UP [latent class analysis ensembled with UMAP (uniform manifold approximation and projection) and PCA (principal components analysis)], an ensemble machine-learning method for clustering multidimensional binary data that does not require prespecifying the number of clusters and is robust to realistic data settings, such as the correlation of variables observed from the same individual and the inclusion of variables unrelated to the underlying subtype. The method ensembles latent class analysis, a model-based clustering method; principal components analysis, a spectral signal processing method; and UMAP, a cutting-edge model-free dimensionality reduction algorithm. In simulations, LACE-UP outperforms gold-standard techniques across a variety of realistic scenarios, including in the presence of correlated and extraneous data. We apply LACE-UP to dietary behavior data from the UK Biobank to demonstrate its power to uncover interpretable dietary subtypes that are associated with lipids and cardiovascular risk.

Common misconceptions and controversies in the management of irritable bowel syndrome

Despite an increase in our understanding of the pathophysiology of irritable bowel syndrome (IBS), in the context of abnormal gut-brain axis communication, and advances in both pharmacological and non-pharmacological treatment of the disorder, there remain areas in which there are misconceptions and controversies in the clinical management of IBS. This Perspective aims to highlight some of the most common misconceptions and controversies in IBS management, including those that the scientific literature has resolved, but for which further education of clinicians dealing with patients with IBS might be required to implement the findings from medical research. Areas of remaining contention are also discussed, as are suggestions as to how these issues could be addressed, both by advances in clinical practice and by further research.

Elevated Fecal Biomarkers of Colo-Rectal Epithelial Cell Activity in Irritable Bowel Syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a common functional gastro-intestinal disorder characterized by discomfort with constipation and/or diarrhea with unclear pathophysiology. We aimed to determine the activities of colorectal eosinophils, neutrophils and epithelial cells by biomarkers in feces reflecting these activities.

METHODS

Fecal samples were collected from 185 patients with IBS before and after 8 weeks of placebo or mesalazine treatment and from 40 healthy subjects. Calprotectin, eosinophil derived neurotoxin (EDN), eosinophil cationic protein (ECP), human neutrophil lipocalin (HNL) (pab/765) or dimer, human phospholipase BII-precursor (HPLBII-P) and myeloperoxidase (MPO) were measured by ELISA. Symptom scores were evaluated by diaries.

RESULTS

HPLBII-P, HNL (pab/765) and EDN, proteins secreted by intestinal epithelial cells, were elevated in IBS patients as compared to healthy subjects (p < 0.0001-p = 0.008). In contrast, the neutrophil proteins calprotectin, MPO and HNL dimer were unaltered. The eosinophilic protein ECP was lower in IBS (p = 0.001). HNL (pab/765) (p = 0.01) and EDN (p = 0.004) increased in IBS patients after mesalazine treatment. Colo-rectal mucosa showed strong staining of HPLBII-P and western blotting of fecal extracts showed the presence of mainly monomeric, epithelial-associated HNL.

CONCLUSIONS

The absence of signs of involvement of neutrophils and eosinophils in IBS suggests that activity of local epithelial cells rather than inflammation may be a major determinant of the disease. The measurements of EDN, HNL (pab/765), and HPLBII-P may serve as potential fecal biomarkers in the study and monitoring of IBS.

Rome Foundation Working Team Report on overlap in disorders of gut-brain interaction

In patients with disorders of gut-brain interaction (DGBI), overlapping non-gastrointestinal conditions such as fibromyalgia, headaches, gynaecological and urological conditions, sleep disturbances and fatigue are common, as is overlap among DGBI in different regions of the gastrointestinal tract. These overlaps strongly influence patient management and outcome. Shared pathophysiology could explain this scenario, but details are not fully understood. This overlap has been shown to be of great relevance for DGBI. In addition, symptoms considered to be caused by a DGBI could have a detectable organic cause, and in patients with a diagnosed organic gastrointestinal disease, symptoms not clearly explained by the pathology defining this organic disease are common. Thus, the aims of this Rome Foundation Working Team Report were to review the literature on overlapping conditions among patients with paediatric and adult DGBI and, based on the available epidemiological and clinical evidence, make recommendations for the current diagnostic and therapeutic approach, and for future research. Specifically, we focused on other DGBI in the same or different gastrointestinal anatomical region(s), DGBI overlap with organic bowel diseases in remission, and DGBI overlap with non-gastrointestinal, non-structural conditions.

Gastrointestinal transit abnormalities in irritable bowel syndrome and their relation to symptoms

INTRODUCTION

Measurement of gastrointestinal (GI) transit is increasingly becoming a valuable tool in understanding the pathophysiology of symptoms of many digestive diseases, including irritable bowel syndrome (IBS). The objective of this article is to review the relevance of GI transit abnormalities for symptoms of IBS. These abnormalities relate to gastric emptying, small bowel transit, and colonic transit (whole gut transit).

AREAS COVERED

The article briefly describes the current methods of assessment, factors that influence the result of these methods and the relationship of abnormalities of GI transit with symptoms that have been reported in IBS patients. Finally, a recommendation to guide the application of transit studies in IBS in both clinical practice and research is provided.

EXPERT OPINION

Gastrointestinal transit is relevant to symptoms of bowel habits (stool frequency and form) and the relevance for other GI symptoms in IBS is not straightforward and needs further characterization. Intervention studies in IBS that incorporate objective measures of gut transit alongside symptom evaluation are warranted. Incorporating artificial intelligence into the methods of measuring transit could improve accuracy and simplify the measurements.

An evidence-based update on the diagnosis and management of irritable bowel syndrome

INTRODUCTION

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction affecting 5% of the population. The cardinal symptoms are abdominal pain and altered stool form or frequency.

AREAS COVERED

Diagnosis and management of IBS. We searched the literature for diagnostic accuracy studies, randomized controlled trials, and meta-analyses. A positive diagnosis of IBS, alongside testing to exclude celiac disease, is recommended. Exhaustive investigation has a low yield. Patients should be offered traditional dietary advice. If response is incomplete, specialist dietetic guidance should be considered. Probiotics may be beneficial, but quality of evidence is poor. First-line treatment of constipation is with laxatives, with secretagogues used where these are ineffective. Anti-diarrheal drugs should be used first-line for diarrhea, with second-line drugs including 5-hydroxytryptamine-3 antagonists, eluxadoline, or rifaximin, where available. First-line treatment of abdominal pain should be with antispasmodics, with gut-brain neuromodulators prescribed second-line. Low-dose tricyclic antidepressants, such as amitriptyline, are preferred. Brain-gut behavioral therapies are effective and have evidence for efficacy in patients refractory to standard therapies.

EXPERT OPINION

Despite substantial advances, there remains scope for improvement in terms of both the diagnosis and management of IBS. Reinforcement of positive diagnostic strategies for the condition and novel treatment paradigms are required.

Unsupervised machine learning highlights the challenges of subtyping disorders of gut-brain interaction

BACKGROUND

Unsupervised machine learning describes a collection of powerful techniques that seek to identify hidden patterns in unlabeled data. These techniques can be broadly categorized into dimension reduction, which transforms and combines the original set of measurements to simplify data, and cluster analysis, which seeks to group subjects based on some measure of similarity. Unsupervised machine learning can be used to explore alternative subtyping of disorders of gut-brain interaction (DGBI) compared to the existing gastrointestinal symptom-based definitions of Rome IV.

PURPOSE

This present review aims to familiarize the reader with fundamental concepts of unsupervised machine learning using accessible definitions and provide a critical summary of their application to the evaluation of DGBI subtyping. By considering the overlap between Rome IV clinical definitions and identified clusters, along with clinical and physiological insights, this paper speculates on the possible implications for DGBI. Also considered are algorithmic developments in the unsupervised machine learning community that may help leverage increasingly available omics data to explore biologically informed definitions. Unsupervised machine learning challenges the modern subtyping of DGBI and, with the necessary clinical validation, has the potential to enhance future iterations of the Rome criteria to identify more homogeneous, diagnosable, and treatable patient populations.

Adverse childhood experiences and alexithymia intensity as predictors of temporal dynamics of functioning in individuals with irritable bowel syndrome: A three-wave latent transition analysis

OBJECTIVE

Despite high prevalence of irritable bowel syndrome (IBS) and its significant negative impact on individuals' quality of life, its etiology remains poorly understood. This prospective study explored whether early life factors (adverse childhood experiences; ACEs) and alexithymia intensity, could explain IBS symptom severity and its effects on psychological functioning over time. We also compared the studied variables between an IBS sample and a healthy control group.

METHOD

Based on the Rome III Diagnostic Criteria for IBS, 245 individuals with a diagnosis of IBS were recruited from a national sample of Poles. The IBS sample completed the following psychometric questionaries in three waves, one month apart: Adverse Childhood Experiences Questionnaire, Toronto Alexithymia Scale, IBS Symptom Severity Score, Short Form Perceived Stress Scale, and Ultra-Brief Patient Health Questionnaire for Anxiety and Depression. Latent transition analysis was used to identify distinct profiles of IBS symptom dynamics.

RESULTS

The IBS group reported a significantly higher number of ACEs, greater alexithymia severity, and more intense levels of stress, anxiety, and depressive symptoms compared to the healthy controls. Four profiles of IBS individuals with distinct dynamics of IBS symptoms, stress, anxiety, and depressive symptoms were extracted, which correlated with the baseline number of ACEs and alexithymia intensity among participants.

CONCLUSION

Childhood adversity and associated problems in emotional processing affect IBS symptom severity. ACEs should be included in IBS screening and considered in the design of individualized multidisciplinary treatment approaches for IBS patients.

Personalisation of therapy in irritable bowel syndrome: a hypothesis

Irritable bowel syndrome (IBS) is a common disorder of gut-brain interaction characterised by symptoms of abdominal pain, occurring at least 1 day per week, and a change in stool frequency or form. Individuals with IBS are usually subtyped according to their predominant bowel habit, which is used to direct symptom-based treatment. However, this approach is probably an oversimplification of a complex and multidimensional condition, and other factors, such as psychological health, are known to influence symptom severity and prognosis. We have previously used latent class analysis, a method of mathematical modelling, to show that people with IBS can be classified into seven unique clusters based on a combination of gastrointestinal symptoms, abdominal pain, extraintestinal symptoms, and psychological comorbidity. The clusters can be used to predict the prognosis of IBS (eg, symptom severity), health-care use (eg, consultation behaviour, prescribing, and costs), and impact (eg, quality of life, work and productivity, activities of daily living, and income). These clusters could also be used to increase the personalisation of IBS treatment that better recognises the heterogenous nature of the condition. We present new data providing additional validation of our seven-cluster model and conduct a comprehensive evidence-based review of IBS management. Based on this evidence, we propose a framework of first-line and second-line treatments according to IBS cluster. Finally, we discuss what further research is needed to implement this approach in clinical practice, including the need for randomised trials comparing cluster-based treatment with conventional treatment according to stool subtype.

Effect of Brain-Gut Behavioral Treatments on Abdominal Pain in Irritable Bowel Syndrome: Systematic Review and Network Meta-Analysis

BACKGROUND & AIMS

Some brain-gut behavioral treatments (BGBTs) are beneficial for global symptoms in irritable bowel syndrome (IBS). United States management guidelines suggest their use in patients with persistent abdominal pain, but their specific effect on this symptom has not been assessed systematically.

METHODS

We searched the literature through December 16, 2023, for randomized controlled trials (RCTs) assessing efficacy of BGBTs for adults with IBS, compared with each other or a control intervention. Trials provided an assessment of abdominal pain resolution or improvement at treatment completion. We extracted data as intention-to-treat analyses, assuming dropouts to be treatment failures and reporting pooled relative risks (RRs) of abdominal pain not improving with 95% confidence intervals (CIs), ranking therapies according to the P score.

RESULTS

We identified 42 eligible randomized controlled trials comprising 5220 participants. After treatment completion, the BGBTs with the largest numbers of trials and patients recruited demonstrating efficacy for abdominal pain, specifically, included self-guided/minimal contact cognitive behavioral therapy (CBT) (RR, 0.71; 95% CI, 0.54-0.95; P score, 0.58), face-to-face multicomponent behavioral therapy (RR, 0.72; 95% CI, 0.54-0.97; P score, 0.56), and face-to-face gut-directed hypnotherapy (RR, 0.77; 95% CI, 0.61-0.96; P score, 0.49). Among trials recruiting only patients with refractory global IBS symptoms, group CBT was more efficacious than routine care for abdominal pain, but no other significant differences were detected. No trials were low risk of bias across all domains, and there was evidence of funnel plot asymmetry.

CONCLUSIONS

Several BGBTs, including self-guided/minimal contact CBT, face-to-face multicomponent behavioral therapy, and face-to-face gut-directed hypnotherapy may be efficacious for abdominal pain in IBS, although none was superior to another.

Decoding IBS: a machine learning approach to psychological distress and gut-brain interaction

PURPOSE

Irritable bowel syndrome (IBS) is a diagnosis defined by gastrointestinal (GI) symptoms like abdominal pain and changes associated with defecation. The condition is classified as a disorder of the gut-brain interaction (DGBI), and patients with IBS commonly experience psychological distress. The present study focuses on this distress, defined from reports of fatigue, anxiety, depression, sleep disturbances, and performance on cognitive tests. The aim was to investigate the joint contribution of these features of psychological distress in predicting IBS versus healthy controls (HCs) and to disentangle clinically meaningful subgroups of IBS patients.

METHODS

IBS patients ( n = 49 ) and HCs ( n = 28 ) completed the Chalder Fatigue Scale (CFQ), the Hamilton Anxiety and Depression Scale (HADS), and the Bergen Insomnia Scale (BIS), and performed tests of memory function and attention from the Repeatable Battery Assessing Neuropsychological Symptoms (RBANS). An initial exploratory data analysis was followed by supervised (Random Forest) and unsupervised (K-means) classification procedures.

RESULTS

The explorative data analysis showed that the group of IBS patients obtained significantly more severe scores than HCs on all included measures, with the strongest pairwise correlation between fatigue and a quality measure of sleep disturbances. The supervised classification model correctly predicted belongings to the IBS group in 80% of the cases in a test set of unseen data. Two methods for calculating feature importance in the test set gave mental and physical fatigue and anxiety the strongest weights. An unsupervised procedure with K = 3 showed that one cluster contained 24% of the patients and all but two HCs. In the two other clusters, their IBS members were overall more impaired, with the following differences. One of the two clusters showed more severe cognitive problems and anxiety symptoms than the other, which experienced more severe problems related to the quality of sleep and fatigue. The three clusters were not different on a severity measure of IBS and age.

CONCLUSION

The results showed that psychological distress is an integral component of IBS symptomatology. The study should inspire future longitudinal studies to further dissect clinical patterns of IBS to improve the assessment and personalized treatment for this and other patient groups defined as disorders of the gut-brain interaction. The project is registered at https://classic.

CLINICALTRIALS

gov/ct2/show/NCT04296552 20/05/2019.

Novel Symptom Subgroups in Individuals With Irritable Bowel Syndrome Predict Disease Impact and Burden

BACKGROUND & AIMS

Current classification systems based on bowel habit fail to capture the multidimensional nature of irritable bowel syndrome (IBS). We previously derived and validated a classification system, using latent class analysis, incorporating factors beyond bowel habit. We applied this in another cohort of people with IBS to assess its ability to capture the impact of IBS on the individual, the health care system, and society.

METHODS

We collected demographic, symptom, and psychological health data from adults in the community self-identifying as having IBS, and meeting Rome IV criteria. We applied our latent class analysis model to identify the 7 subgroups (clusters) described previously, based on overall gastrointestinal symptom severity and psychological burden. We assessed quality of life, health care costs (£1 = $1.20), employment status, annual income, work productivity, and ability to perform work duties in each cluster.

RESULTS

Of 1278 responders, 752 (58.8%) met Rome IV criteria. The 7-cluster model fit the data well. The patients in the 4 clusters with the highest psychological burden, and particularly those in cluster 6 with high overall gastrointestinal symptom severity and high psychological burden, showed lower educational levels, higher gastrointestinal symptom-specific anxiety, were more likely to have consulted a gastroenterologist, and used more drugs for IBS. IBS-related and generic quality of life were impaired significantly in these 4 clusters and significantly fewer individuals reported earning ≥£30,000 per year. Productivity and the ability to work, manage at home, engage in social and private leisure activities, and maintain close relationships all were impacted significantly, and IBS-related health care costs over the previous 12 months were highest in these 4 clusters. In those in cluster 6, costs were more than £1000 per person per year.

CONCLUSIONS

Our clusters identify groups of individuals with significant impairments in quality of life, earning potential, and ability to work and function socially, who are high utilizers of health care.

Anxiety-Related Factors Associated With Symptom Severity in Irritable Bowel Syndrome in Jazan, Saudi Arabia

BACKGROUND

 This study in Jazan, Saudi Arabia aims to identify anxiety-related factors associated with symptom severity in irritable bowel syndrome (IBS). IBS is a common gastrointestinal disorder causing abdominal pain and altered bowel habits. The prevalence of IBS in Saudi Arabia is estimated to be 10%-20% among the general population. Therefore, the present study aimed to determine anxiety-related factors associated with symptom severity in irritable bowel syndrome in Jazan, Saudi Arabia. Understanding these factors will provide insights into the overall impact of IBS on patients' quality of life.

METHODS

The study utilized a cross-sectional, descriptive observational design to examine the general population in Jazan, Saudi Arabia. The sample size of 385 individuals was calculated based on the population size and desired error margin. A convenience sampling technique was employed to select participants who met the inclusion criteria. A validated anonymous self-administered electronic survey was distributed through social media channels. The survey consisted of four sections gathering demographic information, personal risk factors, IBS types with anxiety and risk factors, and a questionnaire to determine the level of anxiety. A pilot study was conducted to improve the survey's clarity. Ethical considerations were followed, and data were analyzed using Statistical Package for Social Sciences (SPSS; IBM Corp., Armonk, NY, USA). Descriptive statistics and significance tests were performed.

RESULT

A study with 637 participants found a 31.08% prevalence of IBS, which was more common in females. Participants with IBS had a higher rate of chronic disease. There were no significant differences in demographic factors between IBS and non-IBS participants. The duration of IBS diagnosis varied, with the majority of IBS with diarrhea (IBS-D) sufferers being diagnosed five years prior. Symptom severity differed among IBS types, with those with an unspecified type reporting the highest percentage of severe symptoms. IBS types were also correlated with anxiety levels, with IBS-D sufferers reporting moderate anxiety and those with an unspecified type reporting severe anxiety.

CONCLUSION

A study with 637 participants found the prevalence of IBS to be 31.08%, with higher rates in females. IBS was associated with chronic diseases and higher anxiety levels. The findings emphasize the need for comprehensive management of IBS, including psychological interventions and dietary modifications, to improve patients' overall health and quality of life. Further research on genetic and modifiable risk factors is needed.

High-Dimensional Clustering of 4000 Irritable Bowel Syndrome Patients Reveals Seven Distinct Disease Subsets

BACKGROUND AND AIMS

Irritable bowel syndrome (IBS) is a pain disorder classified by bowel habits, disregarding other factors that may influence the clinical course. The aim of this study was to determine if IBS patients can be clustered based on clinical, dietary, lifestyle, and psychosocial factors.

METHODS

Between 2013 and 2020, the Mayo Clinic Biobank surveyed and received 40,291 responses to a questionnaire incorporating Rome III criteria. Factors associated with IBS were determined and latent class analysis, a model-based clustering, was performed on IBS cases.

RESULTS

We identified 4021 IBS patients (mean 64 years; 75% women) and 12,063 controls. Using 26 variables separating cases from controls, the optimal clustering revealed 7 latent clusters. These were characterized by perceived health impairment (moderate or severe), psychoneurological factors, and bowel dysfunction (diarrhea or constipation predominance). Health impairment clusters demonstrated more pain, with the severe cluster also having more psychiatric comorbidities. The next 3 clusters had unique enrichment of psychiatric, neurological, or both comorbidities. The bowel dysfunction clusters demonstrated less abdominal pain, with diarrhea cluster most likely to report pain improvement with defecation. The constipation cluster had the highest exercise score and consumption of fruits, vegetables, and alcohol. The distribution of clusters remained similar when Rome IV criteria were applied. Physiologic tests were available on a limited subset (6%), and there were no significant differences between clusters.

CONCLUSIONS

In this cohort of older IBS patients, 7 distinct clusters were identified demonstrating varying degrees of gastrointestinal symptoms, comorbidities, dietary, and lifestyle factors. Further research is required to assess whether these unique clusters could be used to direct clinical trials and individualize patient management.

Exploring new subgroups for irritable bowel syndrome using a machine learning algorithm

Irritable bowel syndrome (IBS) is a complicated gut-brain axis disorder that has typically been classified into subgroups based on the major abnormal stool consistency and frequency. The presence of components other than lower gastrointestinal (GI) symptoms, such as psychological burden, has also been observed in IBS manifestations. The purpose of this research is to redefine IBS subgroups based on upper GI symptoms and psychological factors in addition to lower GI symptoms using an unsupervised machine learning algorithm. The clustering of 988 individuals who met the Rome III criteria for diagnosis of IBS was performed using a mixed-type data clustering algorithm. Nine sub-groups emerged from the proposed clustering: (I) High diarrhea, pain, and psychological burden, (II) High upper GI, moderate lower GI, and psychological burden, (III) High psychological burden and moderate overall GI, (IV) High constipation, moderate upper GI, and high psychological burden, (V) moderate constipation and low psychological burden, (VI) High diarrhea and moderate psychological burden, (VII) moderate diarrhea and low psychological burden, (VIII) Low overall GI, and psychological burden, (IX) Moderate lower GI, and low psychological burden. The proposed procedure led to the discovery of new homogeneous clusters in addition to certain well-known Rome sub-types for IBS.

Re-investigation of functional gastrointestinal disorders utilizing a machine learning approach

BACKGROUND

Functional gastrointestinal disorders (FGIDs), as a group of syndromes with no identified structural or pathophysiological biomarkers, are currently classified by Rome criteria based on gastrointestinal symptoms (GI). However, the high overlap among FGIDs in patients makes treatment and identifying underlying mechanisms challenging. Furthermore, disregarding psychological factors in the current classification, despite their approved relationship with GI symptoms, underlines the necessity of more investigation into grouping FGID patients. We aimed to provide more homogenous and well-separated clusters based on both GI and psychological characteristics for patients with FGIDs using an unsupervised machine learning algorithm.

METHODS

Based on a cross-sectional study, 3765 (79%) patients with at least one FGID were included in the current study. In the first step, the clustering utilizing a machine learning algorithm was merely executed based on GI symptoms. In the second step, considering the previous step's results and focusing on the clusters with a diverse combination of GI symptoms, the clustering was re-conducted based on both GI symptoms and psychological factors.

RESULTS

The first phase clustering of all participants based on GI symptoms resulted in the formation of pure and non-pure clusters. Pure clusters exactly illustrated the properties of most pure Rome syndromes. Re-clustering the members of the non-pure clusters based on GI and psychological factors (i.e., the second clustering step) resulted in eight new clusters, indicating the dominance of multiple factors but well-discriminated from other clusters. The results of the second step especially highlight the impact of psychological factors in grouping FGIDs.

CONCLUSIONS

In the current study, the existence of Rome disorders, which were previously defined by expert opinion-based consensus, was approved, and, eight new clusters with multiple dominant symptoms based on GI and psychological factors were also introduced. The more homogeneous clusters of patients could lead to the design of more precise clinical experiments and further targeted patient care.

Managing pain in irritable bowel syndrome: current perspectives and best practice

INTRODUCTION

Irritable bowel syndrome (IBS) is characterized by chronic symptoms (>6 months) of abdominal pain in combination with a disturbed bowel habit. There is an association between the intensity of abdominal pain and the need for health care utilization. A bidirectionally disordered gut-brain interaction is central in the pathophysiology of IBS where a number of factors, gastrointestinal and non-gastrointestinal, can contribute to the illness experience. In order to treat abdominal pain in IBS, mapping these factors in a multidimensional clinical profile is helpful.

AREAS COVERED

This review covers basic epidemiology and pathophysiology of abdominal pain in IBS, the diagnostic approach, and a multidimensional treatment model where the management of abdominal pain is in focus.

EXPERT OPINION

A personalized treatment of abdominal pain in IBS is possible in patients who understand the diagnosis, the potential of therapies used, and where a good continuity in the patient-doctor relationship is established.

A psychological symptom based machine learning model for clinical evaluation of irritable bowel syndrome

Background: Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by recurrent abdominal pain associated with alterations  in stool form and/or stool frequency. Co-morbidities such as anxiety, depression, fatigue, and insomnia are frequently reported by patients suffering from IBS. Identification of these symptoms should thus be an integral part of an IBS assessment.      However, an optimal tool to screen for core psychological symptoms in IBS is still  missing. Here, we aim to develop a psychological symptom based machine learning model to efficiently help clinicians to identify patients suffering from IBS. Methods: We developed a machine learning workflow to select the most significant psychological features associated with IBS in a dataset including 49 patients with IBS and 35 healthy controls. These features were used to train three different types of machine learning models: logistic regression, decision trees and support vector machine classifiers; which were validated on a holdout validation dataset and an unseen test set. The performance of these models was compared in terms of balanced accuracy scores. Results: A logistic regression model including a combination of symptom features associated with anxiety and fatigue resulted in a balanced accuracy score of 0.93 (0.81-1.0) on unseen test data and outperformed the other comparable models. The same model correctly identified all patients with IBS in a test set (recall score 1) and misclassified one non-IBS subject (precision score 0.91). A complementary post-hoc leave-one-out cross validation analysis including the same symptom features showed similar, but slightly inferior results (balanced accuracy 0.84, recall 0.88, precision 0.86). Conclusions: Inclusion of machine learning based psychological evaluation can complement and improve existing clinical procedure for diagnosis of IBS.

Review article: exclude or expose? The paradox of conceptually opposite treatments for irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a heterogeneous disorder of gut-brain interaction (DGBI) maintained by interacting biological, psychological, and social processes. Interestingly, there are two contrasting yet evidence-based treatment approaches for reducing IBS symptoms: exclusion diets such as those low in fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) and exposure-based cognitive-behavioural therapy (CBT). Exclusion diets recommend patients avoid foods thought to be symptom-inducing, whereas exposure-based CBT encourages patients to expose themselves to foods.

AIMS

To address the paradox of conceptually opposite exclusion diets and exposure-based CBT for IBS.

METHODS

In this conceptual review, we describe the rationale, practical implementation, evidence base and strengths and weaknesses of each treatment. We conducted up-to-date literature search concerning the low FODMAP diet and CBT, and performed a secondary analysis of a previously conducted trial to illustrate a key point in our review.

RESULTS

The low FODMAP diet has demonstrated efficacy, but problems with adherence, nutritional compromise, and heightened gastrointestinal-specific anxiety raise caution. Exposure-based CBT has demonstrated efficacy with substantial evidence for gastrointestinal-specific anxiety as a key mechanism of action. Mediation analysis also showed that increased FODMAP intake mediated decreased symptom severity in exposure-based CBT. However, there is minimal evidence supporting which treatment "works best for whom" and how these approaches could be best integrated.

CONCLUSIONS

Even though exclusion diets and exposure-based CBT are conceptually opposite, they each have proven efficacy. Clinicians should familiarise themselves with both treatments. Further research is needed on predictors, mechanisms and moderators of treatment outcomes.

Quality of life and sleep in individuals with irritable bowel syndrome according to different diagnostic criteria and inflammatory bowel diseases: A comparison using data from a population-based survey

BACKGROUND

A proportion of irritable bowel syndrome (IBS) affected patients does not fulfil Rome criteria despite considerable impairment similarly to that in patients with organic gastrointestinal diseases.This investigation aims to examine differences regarding Mental (MQoL), Physical Quality of Life (PQoL), and sleep between IBS according to Rome III (IBS Rome), clinically defined IBS, inflammatory bowel diseases (IBD), and non-IBS/non-IBD individuals.

METHODS

Data from SHIP-Trend (Study of Health in Pomerania, 2008-2012), a population-based cohort study in Germany, were used.

RESULTS

Response was 50.1% (N = 4420). Prevalence was 3.5% for IBS Rome (95% confidence interval (CI): 3.0 - 4.1%, n = 148), 0.6% for clinically defined IBS (CI: 0.4 - 0.9%, n = 27), and 0.8% for IBD (CI: 0.6 - 1.1%, n = 34). Individuals with IBS Rome (4.54 (CI: -5.92; -3.17)) and clinically defined IBS (4.69 (CI: -7.82; -1.56)) had lower scores for MQoL compared to the non-IBS/non-IBD group. PQoL scores were lowered in IBS Rome (6.39 (CI: -7.89; -4.88)) and IBD (5.37 (CI: -8.51; -2.22)), but not in clinically defined IBS compared to the non-IBS/non-IBD group. IBS Rome was the only gastroenterological condition with higher odds of sleeping problems (odds ratio (OR) "falling asleep": 1.74; CI: 1.29; 2.36; OR "remaining asleep": 1.73; CI: 1.26; 2.38).

CONCLUSIONS

IBS Rome is associated with reduced MQoL, PQoL, and sleep problems. Clinically defined IBS is associated only with reduced MQoL. Heterogeneity within IBS affected patients should be considered in clinical routine and screening for daily life impairment should be performed.

Altered Structural Covariance of Insula, Cerebellum and Prefrontal Cortex Is Associated with Somatic Symptom Levels in Irritable Bowel Syndrome (IBS)

Somatization, defined as the presence of multiple somatic symptoms, frequently occurs in irritable bowel syndrome (IBS) and may constitute the clinical manifestation of a neurobiological sensitization process. Brain imaging data was acquired with T1 weighted 3 tesla MRI, and gray matter morphometry were analyzed using FreeSurfer. We investigated differences in networks of structural covariance, based on graph analysis, between regional gray matter volumes in IBS-related brain regions between IBS patients with high and low somatization levels, and compared them to healthy controls (HCs). When comparing IBS low somatization (N = 31), IBS high somatization (N = 35), and HCs (N = 31), we found: (1) higher centrality and neighbourhood connectivity of prefrontal cortex subregions in IBS high somatization compared to healthy controls; (2) higher centrality of left cerebellum in IBS low somatization compared to both IBS high somatization and healthy controls; (3) higher centrality of the anterior insula in healthy controls compared to both IBS groups, and in IBS low compared to IBS high somatization. The altered structural covariance of prefrontal cortex and anterior insula in IBS high somatization implicates that prefrontal processes may be more important than insular in the neurobiological sensitization process associated with IBS high somatization.

Longitudinal follow-up of a novel classification system for irritable bowel syndrome: natural history and prognostic value

BACKGROUND

Conventionally, irritable bowel syndrome (IBS) is subgrouped using predominant stool form, yet it is a complex disorder, with multiple biopsychosocial contributors. We previously derived and validated a latent class model subgrouping people with IBS into seven clusters based on gastrointestinal and extraintestinal symptoms and psychological profile.

AIMS

To conduct longitudinal follow-up examining the natural history and prognostic value of these clusters.

METHODS

Participants completed a 12-month follow-up questionnaire. We applied our model to these data, comparing cluster membership between the two time points in those still meeting Rome IV criteria at follow-up, including stratifying the analysis by predominant stool pattern, and level of psychological burden, at baseline. We examined whether baseline cluster predicted the course of IBS, and whether starting new treatment was associated with changing cluster.

RESULTS

Eight hundred and eleven participants met Rome IV criteria for IBS at baseline, of whom 452 (55.7%) responded, and 319 (70.6%) still met Rome IV criteria for IBS at follow-up. Of these, 172 (53.9%) remained in the same IBS cluster as at baseline and 147 changed cluster. Cluster membership stratified according to psychological comorbidity was more stable; 84% of those in a cluster with high psychological burden at baseline remained in such a cluster at follow-up. People in clusters with high psychological burden at baseline had more severe symptoms (P < 0.001), received a higher mean number of subsequent treatments (P < 0.001), and were more likely to consult a doctor than people in clusters with low psychological burden (P < 0.001). There was no significant association between starting a new treatment and changing cluster at follow-up.

CONCLUSIONS

Longitudinal follow-up demonstrated little transition between clusters with respect to psychological burden, and these appeared to predict disease course. Directing treatment according to cluster, including earlier use of psychological therapies, and exploring how this approach influences outcomes in IBS, should be examined.

A Novel Method to Classify and Subgroup Patients With IBS Based on Gastrointestinal Symptoms and Psychological Profiles

INTRODUCTION

Conventionally, patients with irritable bowel syndrome (IBS) are subgrouped based on their predominant bowel habit. Given the relevance of psychological comorbidity to IBS symptoms, our aim was to explore an alternative approach to subgrouping by incorporating factors beyond stool form and frequency.

METHODS

We collected demographic, symptom, and psychological health data from 1,375 adult subjects in the community who self-identified as having IBS, identifying 2 cohorts meeting either Rome III or Rome IV criteria. In each cohort, we performed latent class analysis, a method of model-based clustering, to identify specific subgroups (clusters). For each cluster, we drew a radar plot and compared these by visual inspection, describing cluster characteristics.

RESULTS

In total, 1,080 individuals met the Rome III criteria for IBS, and 811 met the Rome IV criteria. In both cohorts, a 7-cluster model was the optimum solution, and the characteristics of the clusters were almost identical between Rome III and IV. Four clusters were defined by the pattern of gastrointestinal symptoms (loose stools and urgency or hard stools and bloating), further differentiated by the presence of abdominal pain not relieved by defecation, and by the extent of psychological comorbidity. Two clusters had below-average gastrointestinal symptoms, differentiated by the extent of psychological comorbidity. The final cluster had well-above-average gastrointestinal symptoms and high levels of psychological comorbidity. The proportion of subjects with severe IBS symptom scores, high levels of perceived stress, and high levels of gastrointestinal symptom-specific anxiety was significantly higher in clusters with high psychological comorbidity (P < 0.001).

DISCUSSION

Latent class analysis identified 7 distinct IBS subgroups characterized by varying degrees of gastrointestinal symptoms, extraintestinal symptoms, and psychological comorbidity. Further research is needed to assess whether they might be used to direct treatment.

Constipation Predominant Irritable Bowel Syndrome and Functional Constipation Are Not Discrete Disorders: A Machine Learning Approach

INTRODUCTION

Chronic constipation is classified into 2 main syndromes, irritable bowel syndrome with constipation (IBS-C) and functional constipation (FC), on the assumption that they differ along multiple clinical characteristics and are plausibly of distinct pathophysiology. Our aim was to test this assumption by applying machine learning to a large prospective cohort of comprehensively phenotyped patients with constipation.

METHODS

Demographics, validated symptom and quality of life questionnaires, clinical examination findings, stool transit, and diagnosis were collected in 768 patients with chronic constipation from a tertiary center. We used machine learning to compare the accuracy of diagnostic models for IBS-C and FC based on single differentiating features such as abdominal pain (a "unisymptomatic" model) vs multiple features encompassing a range of symptoms, examination findings and investigations (a "syndromic" model) to assess the grounds for the syndromic segregation of IBS-C and FC in a statistically formalized way.

RESULTS

Unisymptomatic models of abdominal pain distinguished between IBS-C and FC cohorts near perfectly (area under the curve 0.97). Syndromic models did not significantly increase diagnostic accuracy (P > 0.15). Furthermore, syndromic models from which abdominal pain was omitted performed at chance-level (area under the curve 0.56). Statistical clustering of clinical characteristics showed no structure relatable to diagnosis, but a syndromic segregation of 18 features differentiating patients by impact of constipation on daily life.

DISCUSSION

IBS-C and FC differ only about the presence of abdominal pain, arguably a self-fulfilling difference given that abdominal pain inherently distinguishes the 2 in current diagnostic criteria. This suggests that they are not distinct syndromes but a single syndrome varying along one clinical dimension. An alternative syndromic segregation is identified, which needs evaluation in community-based cohorts. These results have implications for patient recruitment into clinical trials, future disease classifications, and management guidelines.

Efficacy of psychological therapies for irritable bowel syndrome: systematic review and network meta-analysis

OBJECTIVES

National guidelines for the management of irritable bowel syndrome (IBS) recommend that psychological therapies should be considered, but their relative efficacy is unknown, because there have been few head-to-head trials. We performed a systematic review and network meta-analysis to try to resolve this uncertainty.

DESIGN

We searched the medical literature through January 2020 for randomised controlled trials (RCTs) assessing efficacy of psychological therapies for adults with IBS, compared with each other, or a control intervention. Trials reported a dichotomous assessment of symptom status after completion of therapy. We pooled data using a random effects model. Efficacy was reported as a pooled relative risk (RR) of remaining symptomatic, with a 95% CI to summarise efficacy of each comparison tested, and ranked by therapy according to P score.

RESULTS

We identified 41 eligible RCTs, containing 4072 participants. After completion of therapy, the psychological interventions with the largest numbers of trials, and patients recruited, demonstrating efficacy included self-administered or minimal contact cognitive behavioural therapy (CBT) (RR 0.61; 95% CI 0.45 to 0.83, P score 0.66), face-to-face CBT (RR 0.62; 95% CI 0.48 to 0.80, P score 0.65) and gut-directed hypnotherapy (RR 0.67; 95% CI 0.49 to 0.91, P score 0.57). After completion of therapy, among trials recruiting only patients with refractory symptoms, group CBT and gut-directed hypnotherapy were more efficacious than either education and/or support or routine care, and CBT via the telephone, contingency management, CBT via the internet and dynamic psychotherapy were all superior to routine care. Risk of bias of trials was high, with evidence of funnel plot asymmetry; the efficacy of psychological therapies is therefore likely to have been overestimated.

CONCLUSIONS

Several psychological therapies are efficacious for IBS, although none were superior to another. CBT-based interventions and gut-directed hypnotherapy had the largest evidence base and were the most efficacious long term.

TRIAL REGISTRATION NUMBER

The study protocol was published on the PROSPERO international prospective register of systematic reviews (registration number CRD 42020163246).

Anxiety-related factors associated with symptom severity in irritable bowel syndrome

BACKGROUND

Gastrointestinal symptom-specific anxiety and somatization have both been associated with higher symptom severity in patients with irritable bowel syndrome (IBS); however, this relationship has not been explored fully. Moreover, the performance of the visceral sensitivity index (VSI) for measuring gastrointestinal symptom-specific anxiety has not been examined in a UK population. We conducted a cross-sectional survey to examine these issues.

METHODS

Gastrointestinal symptom-specific anxiety was measured using the VSI, and somatization was measured via the patient health questionnaire-12 (PHQ-12) in adults from the UK community with Rome IV-defined IBS. Exploratory factor analysis was performed on the VSI, prior to subsequent analyses, to establish its factor structure. Multiple regression analysis was used to determine the relationship between demographic features, different factors of the VSI, somatization, and IBS symptom severity.

KEY RESULTS

A total of 811 individuals with IBS provided complete data. Factor analysis of the VSI revealed a three-factor structure, accounting for 47% of the variance. The first of these VSI factors and the PHQ-12 were both strongly and independently associated with IBS symptom severity, for the group as a whole and for all four IBS subtypes. Most VSI items concerned with overt gastrointestinal symptom-specific anxiety loaded onto the other two VSI factors that were not associated with symptom severity.

CONCLUSIONS AND INFERENCES

The factor structure of the VSI requires further investigation. Our findings cast doubt on the central role of gastrointestinal symptom-specific anxiety as a driver for symptom severity in IBS. Awareness of both gastrointestinal and extra-intestinal symptoms, however, is strongly associated with symptom severity.

Associations among neurophysiology measures in irritable bowel syndrome (IBS) and their relevance for IBS symptoms

Abnormal gut-brain interactions are common in irritable bowel syndrome (IBS), but the associations between neurophysiological measures and their relation to gastrointestinal (GI) symptoms are poorly understood. Our aim was to explore these relationships and define the most relevant neurophysiology measures for GI symptom severity in IBS. IBS patients underwent small intestinal motility (manometry; fasted and fed contraction frequency, phase III time) and secretion (transmural potential difference), rectal sensorimotor (barostat; sensory thresholds, tone response, compliance), autonomic nervous system (baroreceptor sensitivity and effectiveness), and colonic motor function (transit time) examinations. GI symptom severity (GSRS-IBS), and anxiety and depression (HAD) as a proxy measure of central nervous system (CNS) dysfunction, were assessed. In total 281 IBS patients (Rome II criteria) were included (74% females, median age 36 [interquartile range 28-50] years). Significant correlations between neurophysiology measures were stronger within, rather than between, different neurophysiological examinations. The strongest neurophysiology-symptom correlations occurred between a combination of CNS and visceral sensitivity parameters, and GSRS-IBS total score and pain domain (ρ = 0.40, p < 0.001, and ρ = 0.38, p < 0.001). Associations between GI symptoms in IBS and individual and combinations of neurophysiological factors occurred, primarily in CNS and visceral sensitivity measures, providing new insights into the clinical presentation of IBS.

Postprandial Symptoms in Patients With Functional Dyspepsia and Irritable Bowel Syndrome: Relations to Ultrasound Measurements and Psychological Factors

Background/Aims

Dyspeptic symptoms are common in patients with functional gastrointestinal (GI) disorders, and may be related to visceral hypersensitivity. We aim to explore the relation between visceral hypersensitivity by using an ultrasonographic meal test and questionnaires in patients with irritable bowel syndrome (IBS) and/or functional dyspepsia (FD).

Methods

Patients (FD, n = 94; IBS, n = 88; IBS + FD, n = 66, healthy controls [HC], n = 30) were recruited consecutively and examined with ultrasound of the proximal and distal stomach after drinking 500 mL of a low caloric meat soup, and scored dyspeptic symptoms on a visual analogue scale (0-100 mm) before and after the meal. Psychological symptoms were assessed by Visceral Sensitivity Index (GI specific anxiety, n = 58), and Eysenck's Personality Questionnaire-neuroticism (EPQ-N, n = 203).

Results

Patients with IBS and/or FD reported higher levels of nausea, upper GI discomfort, and epigastric pain both before and after a liquid meal compared to HC (P < 0.001), and had a larger antral area in a fasting state, compared to HC. We found impaired accommodation in 33% of the patients with FD, however ultrasound measurements and symptom severity did not correlate. Symptoms of epigastric pain, fullness and upper GI discomfort positively correlated to Visceral Sensitivity Index and EPQ-N in a fasting state, but not postprandially.

Conclusions

Nausea, upper GI discomfort, and epigastric pain was common in patients with IBS and FD. Both patient groups had enlarged antral area in a fasting state compared to HC. Discomfort and pain were associated to GI specific anxiety and neuroticism in a fasting state.

The Role of Chronic Stress in Normal Visceroception: Insights From an Experimental Visceral Pain Study in Healthy Volunteers

Visceroception is a complex phenomenon comprising the sensation, interpretation, and integration of sensations along the gut-brain axis, including pain or defecatory urgency. Stress is considered a crucial risk factor for the development and maintenance of disorders of gut-brain signaling, which are characterized by altered visceroception. Although the broad role of stress and stress mediators in disturbed visceroception is widely acknowledged, the putative contribution of chronic stress to variations in normal visceroception remains incompletely understood. We aimed to elucidate the role of chronic stress in shaping different facets of visceroception. From a well-characterized, large sample of healthy men and women (N = 180, 50% female), volunteers presenting with low (n = 57) and elevated (n = 61) perceived chronic stress were identified based on the validated Trier Inventory for Chronic Stress (TICS). Visceral sensitivity together with perceived and recalled intensity and defecatory urgency induced by repeated rectal distensions was experimentally assessed, and compared between low and elevated stress groups. Subgroups were compared regarding state anxiety and salivary cortisol concentrations across experimental phases and with respect to psychological measures. Finally, in the full sample and in chronic stress subgroups, a recall bias in terms of a discrepancy between the perception of experimentally-induced symptoms and their recall was tested. Participants with elevated chronic stress presented with increased state anxiety and higher cortisol concentrations throughout the experimental phases compared to the group with low chronic stress. Group differences in visceral sensitivity were not evident. The elevated stress group perceived significantly higher urgency during the stimulation phase, and recalled substantially higher feelings of urgency induced by rectal distensions, while perceived and recalled intensity were comparable between groups. Volunteers with elevated stress exhibited a recall bias in terms of a higher recall relative to mean perception of urgency, whereas no such bias was observed for the intensity of experimental visceral stimulation. Our findings in healthy men and women provide first evidence that the troublesome symptom of urgency might be particularly modifiable by chronic stress and support the relevance of memory biases in visceroception. These results may help to disentangle the impact of chronic stress on altered visceroception in disturbances of gut-brain communication.

Effects of a comprehensive self-management intervention on extraintestinal symptoms among patients with IBS

OBJECTIVE

Adults with irritable bowel syndrome (IBS) often report extraintestinal pain, fatigue, and sleep disturbances in addition to abdominal pain. Few interventions have sought to reduce these extraintestinal symptoms within the IBS population. To address this, we compared the effects of a comprehensive self-management (CSM) intervention to a control intervention (usual care) on extraintestinal pain, fatigue, and sleep disturbances among patients with IBS.

METHOD

Data were obtained from 243 IBS patients participating in two CSM intervention trials. Daily symptom diaries were collected at baseline, 3 and 6 months post-randomization. Daily symptoms of headache, backache, muscle pain, joint pain, fatigue, sleepiness during the day, sleep quality, and refreshed by sleep were analyzed. Analysis of covariance was used to determine the effects of the intervention on each symptom at 3 and 6 months controlling for 'study' and baseline symptom levels.

RESULTS

Patients in the CSM intervention group reported decreased symptoms of fatigue, sleep disturbances, backache and headache compared to usual care at 3 and 6 months. The CSM group also reported significantly decreased joint pain at 3 months compared to usual care, but not 6 months. No significant difference was found for muscle pain.

CONCLUSIONS

An existing CSM intervention is effective in reducing fatigue and sleep disturbances. However, mixed results for extraintestinal pain indicates a need to better differentiate between underlying mechanisms. Addressing such symptoms is important to decrease the overall burden of IBS, reduce health care expenditures, and improve patients' quality of life.

TRIAL REGISTRATION

NCT00907790; NCT00167635.

Symptom-based latent classes of persons with irritable bowel syndrome

A large amount of interindividual variability exists in symptom experiences of persons with irritable bowel syndrome (IBS). Thus, consideration of multiple symptoms to identify distinct symptom subgroups may be useful in directing personalized health strategies for symptom management. We aimed to identify latent classes (i.e., subgroups) of persons with IBS who share similar patterns of symptoms using symptom-related variables (six groups of daily diary symptoms, cognitive beliefs about IBS, and IBS quality of life [QOL]); and to examine how subgroups differed in patient characteristics. Data were derived from a baseline assessment of men and women enrolled in two cognitively-focused intervention trials (N = 332). Using latent class analysis, four latent classes were identified: Class 1 (low symptoms and good QOL, n = 153), Class 2 (low symptoms and moderate QOL, n = 106), Class 3 (high symptoms with diarrhea and poor QOL, n = 38), and Class 4 (high symptoms with low diarrhea and moderate QOL, n = 35). Diarrhea, being female, less formal education, unemployment, and previous history of major depressive disorder were associated with membership in Class 3. Using these distinct symptom profiles, the next step is to explore underlying mechanisms accounting for symptom burden with the goal of designing tailored interventions to reduce that burden.

IBS clinical management in Italy: The AIGO survey

BACKGROUND

Irritable bowel syndrome (IBS) is the most frequent functional gastrointestinal disorder, both in primary and secondary care.

AIMS

(1) To describe diagnostic tools and treatments suggested to IBS patients by Italian gastroenterologists; (2) To evaluate patients' quality of life and psychological involvement and the relationship of these factors with symptom severity.

METHODS

Twenty-six gastroenterologists recorded the demographic and clinical data of 677 IBS patients. Diagnostic and treatment measures taken in the previous year and those suggested by gastroenterologists were analysed.

RESULTS

IBS with constipation was found in 43.4%, with diarrhoea in 21.6%, mixed-IBS in 35.0%. Routine blood tests, ultrasonography, colonoscopy, barium enema and CT were more frequently requested in the previous year than by the gastroenterologists (p < 0.001). Colonoscopy (11%), and ultrasonography (20.4%) were also suggested by the gastroenterologists in a non-negligible number of patients. Abdominal pain and distension, bowel dissatisfaction, anxiety and depression were more severe in females than in males. Quality of life decreased with increasing IBS-symptom severity.

CONCLUSIONS

IBS diagnosis is still largely based on exclusion criteria even if gastroenterologists try to improve diagnostic appropriateness. However, therapy remains symptom-based also in the gastroenterological setting even if gastroenterologists use a wide variety of approaches, including innovative therapies such as linaclotide and psychotherapy.

Cognitive and Behavioral Differences Between Subtypes in Refractory Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal syndrome consisting of different bowel pattern subtypes: diarrhea predominant (IBS-D), constipation predominant (IBS-C), and alternating (IBS-A). This paper aimed to identify whether (a) psychological factors implicated in the cognitive behavioral model of IBS were differentially associated with bowel pattern subtypes, (b) whether there were differences in symptom severity and work and social adjustment across the IBS-subtypes. Analysis was conducted on baseline data of 557 individuals with refractory IBS recruited into the Assessing Cognitive Therapy in Irritable Bowel (ACTIB) randomized controlled trial. Correlations assessed the associations between psychological factors, stool patterns, symptom severity, and work and social adjustment. Hierarchical regressions identified whether cognitive and behavioral factors were significantly associated with frequency of loose/watery stools, hard/lumpy stools and symptom severity while controlling for affective (anxiety and depression) and demographic factors (age, gender, symptom duration). One-way ANOVAs were conducted to assess differences across Rome III classified subtypes (IBS-A, D and C) in cognitive, behavioral, affective, symptom severity, and adjustment measures. Psychological factors were significantly associated with symptom severity and work and social adjustment. Increased avoidance behavior and unhelpful gastrointestinal (GI) cognitions were significantly associated with higher frequency of loose/watery stools. Increased control behaviors were associated with higher frequency of hard/lumpy stools. Cognitive and behavioral differences were significant across the Rome III classified IBS subtypes. There were no differences in anxiety, depression, overall symptom severity, or work and social adjustment. The results are discussed in terms of their utility in tailoring cognitive behavioral treatments to IBS subtypes.

Key mechanisms of cognitive behavioural therapy in irritable bowel syndrome: The importance of gastrointestinal related cognitions, behaviours and general anxiety

BACKGROUND

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterised by abdominal pain and altered bowel movements. Cognitive behavioural therapy (CBT) has been shown to be effective in reducing symptom severity in IBS and enhancing quality of life/functioning. The present study sought to identify how CBT achieves change in these outcomes.

METHOD

Secondary analysis was conducted on 149 patients with irritable bowel syndrome who had been randomised to cognitive behavioural therapy plus an antispasmodic medication or antispasmodic alone. Single and sequential mediation was modelled using structural equation modelling. Gastrointestinal (GI) related avoidance behaviour, safety behaviour, cognitions and general anxiety were included as mediators.

RESULTS

GI safety behaviours, cognitions and general anxiety mediated treatment effect on the outcomes of symptom severity and work and social adjustment. Avoidance behaviour was not a significant mediator for either outcome. Sequential mediation models indicated that unhelpful GI related cognitions reduced before anxiety did, and this sequential path (R➔GI related cognitions➔anxiety➔outcome) was significant for both symptom severity (b = -0.22, CI [-0.40 to -0.90], p = .005) and work and social adjustment (b = -0.26, CI [-0.44 to -0.11], p = .003) where 'R' is randomisation. Reduction in GI safety behaviours also preceded reduction in anxiety. This sequence (R ➔GI safety behaviours➔anxiety➔outcome) was significant for both symptom severity (b = -0.11, CI [-0.24 to -0.01], p = .049) and work and social adjustment (b = -0.12, CI [-0.23 to -0.03], p = .03).

CONCLUSION

Results suggest that it is important for psychological treatments to target IBS specific factors for change.

The gut-brain axis in health neuroscience: implications for functional gastrointestinal disorders and appetite regulation

Over the past few years, scientific interest in the gut-brain axis (i.e., the bidirectional communication system between the gastrointestinal tract and the brain) has exploded, mostly due to the identification of the gut microbiota as a novel key player in this communication. However, important progress has also been made in other aspects of gut-brain axis research, which has been relatively underemphasized in the review literature. Therefore, in this review, we provide a comprehensive, although not exhaustive, overview of recent research on the functional neuroanatomy of the gut-brain axis and its relevance toward the multidisciplinary field of health neuroscience, excluding studies on the role of the gut microbiota. More specifically, we first focus on irritable bowel syndrome, after which we outline recent findings on the role of the gut-brain axis in appetite and feeding regulation, primarily focusing on the impact of subliminal nutrient-related gut-brain signals. We conclude by providing future perspectives to facilitate translation of the findings from gut-brain axis neuroscientific research to clinical applications in these domains.

Subgroups of IBS patients are characterized by specific, reproducible profiles of GI and non-GI symptoms and report differences in healthcare utilization: A population-based study

BACKGROUND

In a previous clinical sample of IBS patients, subgroups characterized by profiles of GI and non-GI symptoms were identified. We aimed to replicate these subgroups and symptom associations in participants fulfilling IBS diagnostic criteria from a population-based study and relate them to healthcare utilization.

METHODS

An Internet-based health survey was completed by general population adults from United States, Canada, and UK. Respondents fulfilling IBS diagnosis (Rome III and IV) were analyzed for latent subgroups using Gaussian mixture model analysis. Symptom measures were derived from validated questionnaires: IBS-related GI symptoms (Rome IV), extraintestinal somatic symptoms (PHQ-12), and psychological symptoms (SF-8).

KEY RESULTS

A total of 637 respondents fulfilled Rome III criteria (average age 46 years, range 18-87, 66% females) and 341 Rome IV criteria (average age 44, range 18-77, 64% female) for IBS. Seven subgroups were identified in the Rome III cohort, characterized by profiles of GI symptoms (constipation-related, diarrhea-related, and mixed, respectively), and further distinguished by the presence or absence of non-GI comorbidities. The Rome IV cohort showed five similar but less distinct subgroups with a preponderance of mixed symptom profiles. Higher severity of non-GI comorbidities was associated with more frequent healthcare visits and medication usage.

CONCLUSIONS AND INFERENCES

In line with previous findings in a clinical IBS cohort, we were able to identify population-based subgroups characterized by a combination of GI symptoms with the additional distinction made by varying severity of non-GI symptoms and with differences in healthcare utilization.

The Relationship Between Daytime Salivary Melatonin and Gastrointestinal Symptoms in Young Adults Seeking Psychiatric Care

OBJECTIVE

The pathophysiology of irritable bowel syndrome (IBS) is not completely understood, although we do know that patients with IBS have a high prevalence of psychiatric comorbidity (mainly depression and anxiety disorders). Melatonin, produced in the gastrointestinal tract, influences gut motility. Psychiatric conditions are associated with circadian disturbances in peripheral melatonin levels. This study aimed to investigate associations between daytime salivary melatonin and gastrointestinal symptoms in young adult psychiatric patients.

METHODS

Ninety-six patients (86% women), aged 18-25 years (M (SD) = 21 (2)), seeking psychiatric care with primarily anxiety disorders, affective disorders, or both were included in the study. Total scores from the Gastrointestinal Symptoms Rating Scale - IBS were compared with salivary melatonin measured at three time points (30 minutes after waking up, at 11:00 hours and 30 minutes after lunch) during the waking hours of 1 day.

RESULTS

After adjustment for potential confounders, melatonin levels in saliva 30 minutes after lunch remained significantly correlated to the total Gastrointestinal Symptoms Rating Scale - IBS score after correction for multiple testing (B = 0.016, SE = 0.006, p = .015, q = 0.045). In a post hoc analysis, symptoms of gastrointestinal pain and bloating contributed most to this association.

CONCLUSIONS

In young adult psychiatric patients, salivary melatonin levels after lunch are associated with gastrointestinal symptoms, which is consistent with the proposed effect of elevated levels of gastrointestinal melatonin on gut motility. This result suggests a link between IBS symptoms and regulation of melatonin in patients with psychiatric disorders.

Heart rate variability characteristics of patients with irritable bowel syndrome and associations with symptoms

BACKGROUND

Disturbed brain-gut interactions are assumed to be of importance for symptom generation in patients with irritable bowel syndrome (IBS). The autonomic nervous system (ANS) is part of the bidirectional brain-gut communication, but previous studies in IBS show diverging results. We aimed to identify subgroups of IBS patients with distinct ANS characteristics differentiating them from healthy controls (HC), and to study associations between ANS status and symptoms.

METHODS

Heart rate variability (HRV) was measured in IBS patients and HC (Holter monitoring: supine and standing positions with controlled respiration and ambulatory 24-hour period). Frequency (5 minutes, supine, standing) and time domains (24 hours, day, night) were analyzed. Validated questionnaires were used to measure gastrointestinal and psychological symptoms in patients. Patients and HC were compared on a univariate and multivariate level (principal component analysis [PCA] and orthogonal partial least squares discriminatory analysis (OPLS-DA)).

KEY RESULTS

We analyzed 158 IBS patients (Rome III) and 39 HC. Patients differed significantly from HC in HRV parameters during daytime and in standing position. In the PCA, a majority of patients overlapped with HC, but the weighted means differed (P < .01). A subset of patients (n = 30; 19%) with an aberrant global HRV profile was identified through PCA and OPLS-DA; these patients reported more severe symptoms of frequent (P < .05) and loose stools (P = .03), as well as urgency (P = .01).

CONCLUSIONS AND INFERENCES

Altered ANS function was demonstrated in patients with IBS, and this might be of particular relevance for symptoms in a subset of the patients.

Efficacy and safety of plecanatide in treating constipation predominant irritable bowel syndrome

INTRODUCTION

Uroguanylin interacting with intestinal Guanylate Cyclase C (GC-C) receptors plays an important role in gastrointestinal fluid and electrolyte homeostasis. Plecanatide is the first uroguanylin analog that stimulates GC-C receptors on gastrointestinal mucosa with pH-sensitive receptor binding. Binding to the GC-C receptor activates intracellular conversion of GTP to cGMP resulting in the stimulation of intestinal fluid secretion. Areas covered: Herein, all published research regarding the development of and clinical experience with plecanatide is reviewed. Clinical study results in patients with Chronic Idiopathic Constipation (CIC) and Irritable Bowel Syndrome with Constipation (IBS-C) are also reviewed. Success in the treatment of CIC and IBS-C is supported by beneficial effects on stool viscosity, Complete Spontaneous Bowel Movements and visceral sensation. Finally, the discussion within focuses on the importance of plecanatide in understanding the physiology of uroguanylin, the pathophysiology of IBS-C and the potential for development of uroguanylin and guanylin analogs. Expert opinion: Given this broad spectrum of potential activity for GC-C agonists, it would not be surprising to see that the use of agents such as plecanatide in new areas grow to a level even greater than the use for the present CIC and IBS-C indications.