Is functional dyspepsia just a subset of the irritable bowel syndrome?

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.

Irritable bowel syndrome: Epidemiology, overlap disorders, pathophysiology and treatment

Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disease with a significant impact on patients' quality of life and a high socioeconomic burden. And the understanding of IBS has changed since the release of the Rome IV diagnosis in 2016. With the upcoming Rome V revision, it is necessary to review the results of IBS research in recent years. In this review of IBS, we can highlight future concerns by reviewing the results of IBS research on epidemiology, overlap disorders, pathophysiology, and treatment over the past decade and summarizing the latest research.

Review article: irritable bowel syndrome: natural history, bowel habit stability and overlap with other gastrointestinal disorders

Symptoms of irritable bowel syndrome (IBS) characteristically fluctuate over time. We aimed to review the natural history of IBS and IBS subgroups including bowel habit disturbances, and the overlap of IBS with other gastrointestinal disorders. The community incidence of IBS is approximately 67 per 1000 person years. The prevalence of IBS is stable over time because symptoms fluctuate and there is a portion who experience resolution of their GI symptoms similar in number to those developing new-onset IBS. The proportion who report resolution of symptoms varies amongst population-based studies from 17% to 55%. There is evidence of substantial movement between subtypes of IBS. For example in a clinical trial cohort, only one in four patients retained their baseline classification throughout the study periods, two in three moved between IBS-C (constipation) and IBS-M (mixed), while over half switched between IBS-D (diarrhoea) and IBS-M. The least stable group was IBS-M. There are very limited data on drivers of bowel habit change in IBS. There are emerging evidence fluctuations in intestinal immune activity might account for symptom variability over time. It is of clinical importance to recognise the substantial overlap of IBS symptoms with other gastrointestinal syndromes including gastro-oesophageal reflux disease. This is important to ensure the correct clinical diagnosis of IBS is made and patients are not over investigated. Knowledge of the natural history, stability of subgroups and overlap of IBS with other gastrointestinal conditions should be considered in therapeutic decision making.

Overlap of Irritable Bowel Syndrome and Functional Dyspepsia in the Clinical Setting: Prevalence and Risk Factors

BACKGROUND

According to Rome IV criteria, functional dyspepsia (FD) and irritable bowel syndrome (IBS) are distinct functional gastrointestinal disorders (FGID); however, overlap of these conditions is common in population-based studies, but clinical data are lacking.

AIMS

To determine the overlap of FD and IBS in the clinical setting and define risk factors for the overlap of FD/IBS.

METHODS

A total of 1127 consecutive gastroenterology outpatients of a tertiary center were recruited and symptoms assessed with a standardized validated questionnaire. Patients without evidence for structural or biochemical abnormalities as a cause of symptoms were then categorized based upon the symptom pattern as having FD, IBS or FD/IBS overlap. Additionally, this categorization was compared with the clinical diagnosis documented in the integrated electronic medical records system.

RESULTS

A total of 120 patients had a clinical diagnosis of a FGID. Based upon standardized assessment with a questionnaire, 64% of patients had FD/IBS overlap as compared to 23% based upon the routine clinical documentation. In patients with severe IBS or FD symptoms (defined as symptoms affecting quality of life), the likelihood of FD/IBS overlap was substantially increased (OR = 3.1; 95%CI 1.9-5.0) and (OR = 9.0; 95%CI 3.5-22.7), respectively. Thus, symptom severity for IBS- or FD symptoms were significantly higher for patients with FD/IBS overlap as compared to patients with FD or IBS alone (p all < 0.01). Age, gender and IBS-subtype were not associated with overlap.

CONCLUSION

In the clinical setting, overlap of FD and IBS is the norm rather than the exception. FD/IBS overlap is associated with a more severe manifestation of a FGID.

Changes of excitatory and inhibitory neurotransmitters in the colon of rats underwent to the wrap partial restraint stress

BACKGROUND

Animal models proposed to reproduce some of the human irritable bowel syndrome (IBS) symptoms are based on the hypothesis that psychosocial stressors play a pivotal role in the IBS etio-pathology. We investigated the wrap restraint stress (WRS) model with the aim to analyze the morphological changes of the entire colonic wall of these animals that showed some of the human IBS symptoms such as visceral hypersensitivity.

METHODS

Male Wistar rats were used and WRS was maintained for 2 h. Abdominal contractions (AC) were recorded in the colon-rectum by balloon distension. Fecal pellets were quantitated. Colonic specimens were examined by routine histology, immunohistochemistry and western blot.

KEY RESULTS

WRS animals were characterized by: (i) increase in AC number and fecal pellets mean weight; (ii) clusters of mononucleated cells, increase in eosinophilic granulocytes and mast cells in the mucosa; (iii) increase in CGRP-immunoreactive (IR) nerve fibers in the lamina propria; (iv) decrease in myenteric NK1r-IR and nNOS-IR neurons and in submucous nNOS-IR neurons; (v) decrease in SP-IR nerve fibers in the muscle wall; (vi) reduction in S100β-IR glia in the entire colonic wall; (vii) increase in CRF1r-IR myenteric neurons; (viii) no change in ChAT-IR neurons, smooth muscle cells and interstitial cells of Cajal.

CONCLUSIONS AND INFERENCES

The present results support the consistency of the WRS as a potential model where part of the human IBS signs and symptoms are reproduced. The changes in glial cells and in excitatory and inhibitory neurotransmitters might represent the substrate for the dysmotility and hypersensitivity.

Multi-Dimensional Gastrointestinal Symptom Severity Index: Validation of a Brief GI Symptom Assessment Tool

Few instruments have been developed and validated for the evaluation of multi-dimensional GI symptoms. The Gastrointestinal Symptoms Severity Index (GISSI), a multi-dimensional, self-report instrument, was designed as a brief measure of the frequency, severity, and bothersomeness of individual GI and pelvic floor/urogynecologic symptoms.

AIM

To report the psychometric properties of the GISSI subscales, including factorial structure, validity, and internal consistency.

METHODS

The GISSI included 32 items that assessed upper and lower GI symptoms and seven items related to pelvic floor/urogynecologic symptoms. A total of 934 patients presenting for upper and lower GI complaints completed the questionnaire between January 2013 and December 2013. The sample was randomly split into derivation (n = 466) and validation datasets (n = 468). A non-patient sample of 200 was collected separately.

RESULTS

Exploratory factor analysis supported a six-factor model for the derivation sample that accounted for 69.3 % of the total variance. The six GI symptom clusters were labeled as constipation/difficult defecation (five items), abdominal pain/discomfort (four items), dyspepsia (four items), diarrhea/anal incontinence (four items), GERD/chest symptoms (four items), and nausea/vomiting (two items). Inclusion of additional items related to female pelvic floor/urogynecologic symptoms resulted in a separate factor. Confirmatory factor analysis of the validation dataset supported the a priori hypothesized six-factor measurement model (Χ (2)(428) = 1462.98; P < 0.001; GFI = .88; RMSEA = .051).

CONCLUSION

The GISSI demonstrated good to excellent psychometric properties and provided multi-dimensional scaling of prominent GI symptom clusters. Further validation may provide an efficient, valid, and reliable measure of patient-reported clinical outcomes.

Obsessive-compulsive disorder in general hospital outpatients: prevalence, correlates, and comorbidity in Lanzhou, China

INTRODUCTION

The prevalence of obsessive-compulsive disorder (OCD), risk factors, and comorbidity rates of Chinese outpatients in Lanzhou general hospitals are unknown.

METHOD

The prevalence rate of OCD was estimated in a representative sample of outpatients in three classes of general hospitals in Lanzhou, China. The rate of OCD within the sample, which was composed of 1,576 individuals aged 16 years or older, was assessed using the World Health Organization Composite International Diagnostic Interview Version 3.0.

RESULTS

The weighted prevalence of OCD were 4.31% (lifetime), 2.86% (12-month), and 1.97% (30-day). Multivariate logistic regression identified the following independent predictors of having lifetime OCD: having a higher level of education, being unemployed, an internal medicine outpatient, a female, 16-35 years old, divorced/widowed/separated, and having a low family income. OCD had a significant comorbid association with neuroses, based on the International Statistical Classification of Diseases and Related Health Problems-10th Revision.

DISCUSSION

These findings show a lower prevalence rate of OCD in Lanzhou general hospitals than that reported for some specialized outpatient clinics in Western countries. Further investigations are required to explore the relationships between OCD and the risk factors identified in the current study. Resolving methodological problems may lead to more accurate prevalence estimates in future epidemiological studies. Our findings suggest that there is an urgent need to improve the ability of clinicians to detect OCD in outpatients.

Advances in research of esophageal visceral hypersensitivity

Gastroesophageal reflux disease (GERD) is a common disorder that is often associated with unpleasant symptoms requiring utilization of health care resource. Both animal and clinical studies suggest that a variety of receptors on afferent nerves sensitized upon exposure to acid increase afferent input to the spinal cord dorsal horn neurons and lead to a reduction in threshold of these neurons together with an increase in their receptive field. This increased sensitivity of primary afferent nerves is described as peripheral sensitization, whereas the consequent increase in sensitivity of the spinal dorsal horn neurons is described as central sensitization. Once these mechanisms have been established, they can cause a long-term increase in sensitivity of tissues to previously innocuous stimuli. Furthermore, psychological stress and mechanical stimulation both have been shown to increase DIS and may therefore facilitate peripheral sensitization. Currently peripheral and central sensitizations are considered to be important mechanisms of esophageal pain hypersensitivity and occurrence of symptoms to even physiological amounts of acid. In these patients treatments aimed at reducing neuronal sensitivity may be effective. This article mainly focuses on the recent advances in research of esophageal visceral hypersensitivity.

Psychopathological features of irritable bowel syndrome patients with and without functional dyspepsia: a cross sectional study

Background

Irritable bowel syndrome (IBS) and functional dyspepsia (FD) show considerable overlap and are both associated with psychiatric comorbidity. The present study aimed to investigate whether IBS patients with FD show higher levels of psychopathology than those without FD. As a preliminary analysis, it also evaluated the psychopathological differences, if any, between IBS patients featuring the two Rome III-defined FD subtypes, i.e. postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS).

Methods

Consecutive outpatients (n = 82, F = 67, mean age 41.6 ± 12.7 years) referred to our third level gastroenterological centre, matching the Rome III criteria for IBS and, if present, for concurrent FD, were recruited. They were asked to complete a 90-item self-rating questionnaire, the Symptom Checklist 90 Revised (SCL-90-R), in order to assess the psychological status. Comparisons between groups were carried out using the non-parametric Mann-Whitney U test.

Results

Patients with IBS only were 56 (68.3%, F = 43, mean age 41.6 ± 13.3 years) and patients with both IBS and FD were 26 (31.7%, F = 24, mean age 41.8 ± 11.5 years), 17 of whom had PDS and 9 EPS. Patients with both IBS and FD scored significantly higher on the SCL-90-R GSI and on eight out of the nine subscales than patients with IBS only (P ranging from 0.000 to 0.03). No difference was found between IBS patients with PDS and IBS patients with EPS (P ranging from 0.07 to 0.97), but this result has to be considered provisional, given the small sample size of the two subgroups.

Conclusions

IBS-FD overlap is associated with an increased severity of psychopathological features. This finding suggests that a substantial subset of patients of a third level gastroenterological centre with both IBS and FD may benefit from psychological assessment and treatment.

Psychopathological features of irritable bowel syndrome patients with and without functional dyspepsia: a cross sectional study

BACKGROUND

Irritable bowel syndrome (IBS) and functional dyspepsia (FD) show considerable overlap and are both associated with psychiatric comorbidity. The present study aimed to investigate whether IBS patients with FD show higher levels of psychopathology than those without FD. As a preliminary analysis, it also evaluated the psychopathological differences, if any, between IBS patients featuring the two Rome III-defined FD subtypes, i.e. postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS).

METHODS

Consecutive outpatients (n = 82, F = 67, mean age 41.6 ± 12.7 years) referred to our third level gastroenterological centre, matching the Rome III criteria for IBS and, if present, for concurrent FD, were recruited. They were asked to complete a 90-item self-rating questionnaire, the Symptom Checklist 90 Revised (SCL-90-R), in order to assess the psychological status. Comparisons between groups were carried out using the non-parametric Mann-Whitney U test.

RESULTS

Patients with IBS only were 56 (68.3%, F = 43, mean age 41.6 ± 13.3 years) and patients with both IBS and FD were 26 (31.7%, F = 24, mean age 41.8 ± 11.5 years), 17 of whom had PDS and 9 EPS. Patients with both IBS and FD scored significantly higher on the SCL-90-R GSI and on eight out of the nine subscales than patients with IBS only (P ranging from 0.000 to 0.03). No difference was found between IBS patients with PDS and IBS patients with EPS (P ranging from 0.07 to 0.97), but this result has to be considered provisional, given the small sample size of the two subgroups.

CONCLUSIONS

IBS-FD overlap is associated with an increased severity of psychopathological features. This finding suggests that a substantial subset of patients of a third level gastroenterological centre with both IBS and FD may benefit from psychological assessment and treatment.

Perception of gastro-oesophageal reflux

Gastro-oesophageal reflux disease (GORD) is common and often associated with unpleasant symptoms requiring utilisation of health care resource. While in the majority of patients symptom resolution occurs with acid suppressant therapy, in a proportion this treatment is ineffective in resolving symptoms. This is particularly the case in patients with non-erosive reflux disease (NERD) and functional heartburn (FH). It is increasingly being recognised that the presence of acid in the oesophagus can cause dilated intercellular spaces (DIS) which increases the exposure of the sub-epithelial nerves to the acid. Experimental studies in both animals and humans suggest that a variety of receptors on afferent nerves can be sensitised upon exposure to acid so that there is increased afferent input to the spinal cord dorsal horn neurons which leads to a reduction in threshold of these neurons together with an increase in their receptive field. This increased sensitivity of primary afferent nerves is described as peripheral sensitisation, whereas the consequent increase in sensitivity of the spinal dorsal horn neurons is described as central sensitisation. Once these mechanisms have been established they can cause a long term increase in sensitivity of tissues to previously innocuous stimuli. Furthermore, psychological stress has been shown to increase DIS and may therefore facilitate peripheral sensitisation. Currently peripheral and central sensitisations are considered to be important mechanisms of oesophageal pain hypersensitivity and occurrence of symptoms to even physiological amounts of acid. In these patients treatments aimed at reducing neuronal sensitivity may be effective in the management.

Validation of symptom-based diagnostic criteria for irritable bowel syndrome: a critical review

This article reviews the evidence for validity of symptom-based criteria (Manning, Rome I, Rome II, and Rome III) for irritable bowel syndrome (IBS). Two kinds of validations are reported: (i) studies testing whether symptom criteria discriminate patients with structural disease at colonoscopy from patients without structural disease; and (ii) studies testing whether symptom criteria discriminate patients presumed to have IBS by positive diagnosis from healthy subjects or patients with other functional and structural disorders. The first study type addresses an important clinical management question but cannot provide meaningful information on the sensitivity or positive predictive value because IBS is defined only by exclusion of structural disease. Specificity is modest (about 0.7) but can be improved to 0.9 by the addition of red flag signs and symptoms. The second type of study judges validity by whether the symptom criteria consistently perform as predicted by theory. Here, factor analysis confirms consistent clusters of symptoms corresponding to IBS; symptom-based criteria agree reasonably well (sensitivity, 0.4-0.9) with clinical diagnoses made by experienced clinicians; and patients with a clinical diagnosis of IBS who fulfill Rome II criteria have greater symptom severity and poorer quality of life than patients with a clinical diagnosis of IBS who do not fulfill Rome criteria. There are no consistent differences in sensitivity or specificity between Manning, Rome I, and Rome II. Both study types support the validity of symptom-based IBS criteria. Tests of Rome III are needed.

A randomised controlled trial of structured nurse-led outpatient clinic follow-up for dyspeptic patients after direct access gastroscopy

Background

Dyspepsia is a common disorder in the community, with many patients referred for diagnostic gastroscopy by their General Practitioner (GP). The National Institute of Clinical Excellence (NICE) recommends follow-up after investigation for cost effective management, including lifestyle advice and drug use. An alternative strategy may be the use of a gastro-intestinal nurse practitioner (GNP) instead of the GP. The objective of this study is to compare the effectiveness and costs of systematic GNP led follow-up to usual care by GPs in dyspeptic patients following gastroscopy.

Results

Direct access adult dyspeptic patients referred for gastroscopy; without serious pathology, were followed-up in a structured nurse-led outpatient clinic. Outcome measurement used to compare the two study cohorts (GNP versus GP) included Glasgow dyspepsia severity (Gladys) score, Health Status Short Form 12 (SF12), ulcer healing drug (UHD) use and costs. One hundred and seventy five patients were eligible after gastroscopy, 89 were randomised to GNP follow-up and 86 to GP follow-up. Follow-up at 6 months was 81/89 (91%) in the GNP arm and 79/86 (92%) in the GP arm. On an intention to treat analysis, adjusted mean differences (95%CI) at follow-up between Nurse and GP follow-up were: Gladys score 2.30 (1.4–3.2) p < 0.001, SF12 140.6 (96.5–184.8) p =< 0.001 and UHD costs £39.60 (£24.20–£55.10) p =< 0.001, all in favour of nurse follow-up.

Conclusion

A standardised and structured follow-up by one gastrointestinal nurse practitioner was effective and may save drug costs in patients after gastroscopy. These findings need replication in other centres.

Functional gastrointestinal disorder is associated with increased non-gastrointestinal healthcare consumption in the general population

OBJECTIVES

Comparison of comorbidity and healthcare consumption in primary healthcare subjects with persistent functional gastrointestinal disorder (FGID) and a strictly gastrointestinal (GI) symptom-free group (SSF).

METHODS

A stratified sample (n=1428, 21-86 years) of subjects living in the Osthammar community, Sweden, was limited to half of the community and classified through the Abdominal Symptom Questionnaire (ASQ) into two study groups, one with persistent FGID (n=71), another SSF (n=48). Symptoms were re-evaluated by means of the ASQ at a surgery visit, as was healthcare consumption during 2 years, and the levels of anxiety and depression, as measured with the Hospital Anxiety and Depression Scale. Diagnoses were set according to The International Classification of Diseases (ICD)-9 and the 14 diagnostic groups.

RESULTS

Of the FGID patients, 97% had a non-GI diagnosis, compared with 100% of SSF (ns). The mean number of doctors' consultations (OR=3.5), phone calls to doctors (OR=3.4), number of prescriptions (OR=2.4) and number of set diagnoses (OR=3.9), anxiety level (OR=11.5) and depression (OR=5.2) were all statistically significantly higher (p<0.05) for FGID than for SSF, while the number of referrals and sick leave were not. Besides a GI diagnosis, there was no significant difference (p>0.05) in the spectrum of morbidity in terms of ICD-9 subgroup classification, except an increased proportion of older SSF subjects with circulatory disorders and hypertension.

CONCLUSIONS

Functional gastrointestinal disorders are related to an increased demand on primary healthcare because of an increased overall comorbidity, which signifies a need for a holistic healthcare approach.

Functional chest pain: esophageal or overlapping functional disorder

BACKGROUND

Whether patients with functional chest pain have an esophageal or overlapping functional disorder of the gut is unclear. We investigated the prevalence of functional gastrointestinal disorders in patients with functional chest pain.

METHODS

One hundred patients with functional chest pain and normal cardiac, endoscopic, and manometric studies were evaluated for esophageal hypersensitivity with a balloon distension test. Subsequently, a modified Rome II functional bowel disorder questionnaire was mailed to these subjects. Prevalence of irritable bowel syndrome (IBS) and other functional disorder were determined using the Rome II criteria. In addition, we assessed the prevalence of chest pain in 81 patients with functional constipation.

RESULTS

There were 69 responders (54 women); 2 were excluded. Fifty-five patients (82%) fulfilled criteria for other functional disorders besides chest pain. Although there was an overlap, IBS (27%) and abdominal bloating (22%) were most common; dyspepsia (7%), dysphagia (7%), nonspecific bowel disorder (7%), constipation (4%), abdominal pain (3%), and diarrhea (1%) were less common. Among responders, 52 (78%) had esophageal hypersensitivity and 15 (22%) had normosensitivity, with similar prevalence of functional disorders. Thirty-two (39%) of the subjects with functional constipation reported chest pain occasionally, and 5 (6%) frequently.

CONCLUSIONS

Approximately 80% of patients with functional chest pain exhibit features of other functional disorders including IBS suggesting an overlap. This association is independent of esophageal hypersensitivity. Recognition of this overlap may facilitate better management of these patients.

Disturbed bowel habits in patients with non-ulcer dyspepsia

BACKGROUND; Emerging medications for non-ulcer-dyspepsia, such as the serotonin-receptor modulators, also affect bowel habits by altering colonic transit. If drugs that alter colonic function were to prove useful in non-ulcer dyspepsia, knowledge of baseline bowel habit disturbances would be potentially critical.

AIM

To estimate the rate of non-ulcer dyspepsia patients with clinically relevant constipation or diarrhoea potentially precluding use of motility agents.

METHODS

Consecutive patients with non-ulcer dyspepsia (n = 79), gastro-oesophageal reflux disease (n = 135) and organic upper gastrointestinal disease (upper gastrointestinal disease; n = 36) completed a validated symptom questionnaire evaluating predominant bowel habits in the last year.

RESULTS

Prevalence of constipation was higher in non-ulcer dyspepsia (34%) than in gastro-oesophageal reflux disease (P = 0.01) and organic upper gastrointestinal disease (P = 0.01), prevalence of alternating diarrhoea/constipation (24%) and diarrhoea (22%) was similar, while prevalence of normal bowel habits was significantly less in non-ulcer dyspepsia (20%; P = 0.01 vs. gastro-oesophageal reflux disease and P < 0.01 vs. organic upper gastrointestinal disease). Constipation was particularly frequent in ulcer-like and dysmotility-like non-ulcer dyspepsia, while prevalence of diarrhoea was lowest in dysmotility-like non-ulcer dyspepsia. A normal bowel habit was equally uncommon in male (21%) and female non-ulcer dyspepsia patients (20%).

CONCLUSIONS

Only one of five non-ulcer dyspepsia patients had normal bowel habits based on clinical symptoms; constipation is particularly prevalent. Patients with functional dyspepsia who are prescribed motility altering drugs should be evaluated by taking a thorough bowel habit history.

Racial differences in epidemiology of irritable bowel syndrome alone, un-investigated dyspepsia alone, and "overlap syndrome" among african americans compared to Caucasians: a population-based study

There is A paucity of data on racial differences in epidemiology of irritable bowel syndrome (IBS) alone and un-investigated dyspepsia (UD) alone compared to "overlap syndrome" (OS). We conducted a random survey (n = 990). Subjects completed a questionnaire which included Rome II criteria for IBS and functional dyspepsia (FD). Among African Americans, the prevalence of IBS alone, UD alone, and OS was 0.6%, 17%, and 7.3%, respectively. It was 0%, 13%, and 13% among Caucasian Americans. All but four patients with IBS had UD. Among patients with UD, OS was seen in 30% of African Americans, compared to 50% among Caucasian Americans. Among African Americans, UD patients were younger compared to OS patients. African Americans with UD were more likely than OS patients to have children. Marital status, education, and household income were not a factor among Caucasians. African Americans patients below poverty level were more likely to have UD than OS (22% vs 10%). Considering patients with UD alone, race, age, sex, marital status, number of children, education, and income level were not different between African Americans and Caucasians. Compared to African Americans, Caucasians with OS were likely to be married and live in an urban area. There was a higher prevalence of OS among Caucasians with lower education. OS is 2.5 times more likely to occur among Caucasians compared to African Americans. We conclude that OS is more common among Caucasians than African Americans. IBS and OS are virtually synonymous.

Rectal distension modulates canine gastric tone and accommodation

Rectal distension affects upper GI myoelectrical activity and motility. The aim of this experiment was to investigate the effect of rectal distension on gastric tone, accommodation, and the underlying mechanism. Seven healthy dogs were surgically prepared and studied. Gastric tone and accommodation were assessed with a barostat. In Experiment 1, the effect of rectal distension on gastric tone and accommodation was evaluated; in Experiment 2, rectal distensions with various volumes were randomly applied and its effects on gastric tone were evaluated; and in Experiment 3, the role of the cholinergic pathway in distension-induced gastric relaxation was assessed. The results showed the following. (1) Rectal distension exerted an inhibitory effect on gastric tone, and this response was distension volume-dependent. (2) Postprandial gastric volume was similar in the control (468.6 +/- 24.7 ml) and the distension study (463.2 +/- 17.5 ml). However, rectal distension increased the preprandial gastric volume, and subsequently decreased the extent of gastric accommodation (139.3 +/- 34.7 ml), which was significantly lower than that of the control (383.2 +/- 26.3 ml; P < 0.001). (3) An intravenous bolus of atropine increased the astric volume from the baseline of 89.4 +/- 12.6 ml to 161.5 +/- 9.8 ml (P < 0.01), and subsequent rectal distension further increased this volume, but the overall change was comparable between the control (297.6 +/- 18.7 ml) and the atropine study (312.1 +/- 21.9 ml; P > 0.05). In conclusion, rectal distension inhibits gastric tone in a volume-dependent manner and impairs gastric accommodation. Atropine dose not block the effect of rectal distension on proximal gastric tone, suggesting that the observed effect may not be mediated by cholinergic pathway.

Functional dyspepsia pathogenesis and therapeutic options--implications for management

Functional dyspepsia is far more common than dyspepsia due to organic disease, both in the community and general practice. Proposed aetiopathogenic factors include gastric acid, Helicobacter pylori infection, delayed emptying, hypersensitivity or impaired accommodation of the stomach, dysfunction of the duodenum or brain-gut axis, psychosocial morbidity and post-infective mucosal damage. More effective therapy will depend on the development of drugs targeted at these putative pathophysiological mechanisms. On current evidence tricyclic antidepressants appear to be more effective than either acid suppressants or H. pylori eradication.

Psychological illness is commonly associated with functional gastrointestinal disorders and is important to consider during patient consultation: a population-based study

BACKGROUND

Some individuals with functional gastrointestinal disorders (FGID) suffer long-lasting symptoms without ever consulting their doctors. Our aim was to study co-morbidity and lifestyle differences among consulters and non-consulters with persistent FGID and controls in a defined adult population.

METHODS

A random sample of the general adult Swedish population was obtained by a postal questionnaire. The Abdominal Symptom Questionnaire (ASQ) was used to measure GI symptomatology and grade of GI symptom severity and the Complaint Score Questionnaire (CSQ) was used to measure general symptoms. Subjects were then grouped for study by their symptomatic profiles. Subjects with long-standing FGID (n = 141) and subjects strictly free from gastrointestinal (GI) symptoms (n = 97) were invited to attend their local health centers for further assessment.

RESULTS

Subjects with FGID have a higher risk of psychological illness [OR 8.4, CI95(4.0-17.5)] than somatic illness [OR 2.8, CI95(1.3-5.7)] or ache and fatigue symptoms [OR 4.3, CI95(2.1-8.7)]. Subjects with psychological illness have a higher risk of severe GI symptoms than controls; moreover they have a greater chance of being consulters. Patients with FGID have more severe GI symptoms than non-patients.

CONCLUSION

There is a strong relation between extra-intestinal, mental and somatic complaints and FGID in both patients and non-patients. Psychological illness increases the chance of concomitantly having more severe GI symptoms, which also enhance consultation behaviour.

Impact of coexisting irritable bowel syndrome on symptoms and pathophysiological mechanisms in functional dyspepsia

Epidemiological studies suggest considerable overlap between functional dyspepsia (FD) and irritable bowel syndrome (IBS).

AIM

The aim of the present study was to investigate whether coexisting IBS is also associated with symptom pattern or pathophysiology in FD.

METHODS

In 309 consecutive FD patients (207 women, age 42 +/- 0.8 yr), questionnaires were used to assess the dyspepsia symptom pattern and the Rome II criteria for IBS. The overall symptom severity was calculated adding the severity score (0-3, 0 = absent, 3 = severe) of eight dyspepsia symptoms. All patients underwent Helicobacter pylori testing, gastric barostat to determine sensitivity to distention and accommodation to a meal, and gastric emptying breath test.

RESULTS

Fifty-four percent of the patients had FD alone, whereas 46% had FD + IBS. FD + IBS patients were more likely to be female (75%vs 60%, p < 0.01) and to have a greater weight loss (5.4 +/- 0.6 vs 3.5 +/- 0.4 kg, p < 0.05). Coexisting IBS did not increase the risk of having any of the dyspeptic symptoms but the overall symptom severity was significantly higher in FD + IBS (12.4 +/- 0.4 vs 9.8 +/- 0.3, p < 0.01). FD + IBS patients had a lower threshold for first perception (2.9 +/- 0.3 vs 3.8 +/- 0.3 mmHg, p < 0.05) and for discomfort (7.9 +/- 0.4 vs 9.5 +/- 0.5 mmHg, p < 0.05) and a greater prevalence of hypersensitivity to gastric distention (44%vs 28%, p < 0.05). Gastric emptying, accommodation to a meal, and prevalence of H. pylori infection did not differ in the two groups.

CONCLUSION

About half of the FD patients fulfill the Rome II criteria for IBS. FD + IBS is more prevalent in female patients and is associated with a higher weight loss, with greater overall symptom severity, and with hypersensitivity to distention.

The effect of new diagnostic criteria for irritable bowel syndrome on community prevalence estimates

The 'Rome' criteria for irritable bowel syndrome (IBS) have evolved over 15 years with four published versions. The impact of these changes on community prevalence rates is not known. Study aims were to estimate the prevalence of IBS using the four Rome criteria and agreement between Rome II and previous criteria. Questionnaires were mailed to a random sample of Olmsted County, Minnesota residents in 1992. Age- and gender-adjusted prevalence estimates were calculated for Rome II (1999), Rome I (1992), Rome (1990), and Rome (1989) criteria. Per cent agreement and kappa values were calculated to assess agreement. Of 892 eligible subjects, 643 (72%) responded. The age- and gender-adjusted prevalence of IBS was 5.1% [95% confidence interval (CI): 3.1, 7.0], 6.8% (95% CI: 4.7, 8.9), 5.1% (95% CI: 3.2, 7.1) and 27.6% (95% CI: 23.6, 31.5), respectively. In comparison with Rome II criteria, per cent agreement and kappa values were 97.2% and 0.78 (95% CI: 0.69, 0.88), 96.4% and 0.68 (95% CI: 0.55, 0.80), and 79.0% and 0.29 (95% CI: 0.19, 0.40), respectively. Thus, although differences were seen with the older criteria, compared with the Rome I criteria, good agreement was seen and community prevalence estimates were similar with the Rome II criteria.

Factor analysis of bowel symptoms in US and Italian populations

BACKGROUND AND AIMS

Functional gastrointestinal disorders are diagnosed by the presence of a characteristic set of symptoms. Aims of this study were to validate the Rome symptom criteria by factor analysis and to determine whether symptoms cluster in the same way in different cultures.

METHODS

One thousand forty-one gastroenterology clinic patients in the US (response rate 53%) and 228 family members accompanying clinic patients in Italy (84%) completed a previously validated symptom questionnaire. Factor analysis identified clusters of symptoms which are highly correlated with each other, and these were compared to the Rome diagnostic criteria.

RESULTS

In the US, 13 factors were identified. The irritable bowel factor was composed of three core symptoms corresponding to the Rome II classification system. Two dyspepsia factors were identified which correspond to the ulcer- and motility-like subtypes proposed in the Rome I classification system. All symptoms of constipation formed a single cluster as proposed in the Rome II classification system. Symptom clusters in the US agreed well with symptom clusters identified in Italian subjects.

CONCLUSIONS

Empirically derived symptom clusters agree in most respects with the Rome II classification system and support their validity. These symptom clusters are independent of cultural differences in diet and behaviour.

Overlapping upper and lower gastrointestinal symptoms in irritable bowel syndrome patients with constipation or diarrhea

OBJECTIVES

Distinguishing between irritable bowel syndrome (IBS) and functional dyspepsia can be challenging because of the variations in symptom patterns, which commonly overlap. However, the overlap is poorly quantified, and it is equally uncertain whether symptom patterns differ in subgroups of IBS arbitrarily defined by primary bowel patterns of constipation (IBS-C) and diarrhea (IBS-D). We aimed to determine and to compare the distribution of GI symptoms, both, upper and lower, among IBS-C and IBS-D patients.

METHODS

A total of 121 consecutive patients presenting with a diagnosis of IBS were grouped according to primary bowel symptoms as IBS-C (58 women and 18 men, mean age 47 +/- 17 yr) or IBS-D (26 women and 19 men, mean age 47 +/- 15 yr). The Hopkins Bowel Symptom Questionnaire, which includes a brief Quality of Life assessment, and the Hopkins Symptom Checklist 90-Revised were completed by all patients at intake.

RESULTS

IBS-C patients reported significantly more overall GI symptoms when compared to patients with IBS-D (6.67 vs 4.62, respectively, p<0.001). Abdominal pain patterns differed in patients with IBS-C versus IBS-D (lower abdominal pain: 40.8% vs 24.4% p=0.05 and upper abdominal pain: 36.8% vs 24.4%, respectively). Bloating was substantially more common in IBS-C patients (75%) than in IBS-D (40.9%). There were no significant differences in personality subscales by IBS subgroup; however, somatization was positively associated with multiple symptom reports and was negatively correlated with quality of life.

CONCLUSIONS

Upper GI symptoms consistent with functional dyspepsia were more frequent in IBS-C. Although there was considerable overlap of upper and lower GI symptoms in patients with IBS-C and IBS-D, the former had more frequent lower abdominal pain and bloating.

Validation of Rome II criteria for functional gastrointestinal disorders by factor analysis of symptoms in Asian patient sample

BACKGROUND

It has been unclear as to whether the Rome II criteria could be applied to patients in the Asia region with functional gastrointestinal (GI) diseases. The aim of the present study was to determine if symptoms of Asian patients with functional gastrointestinal disorders formed groups which corresponded to the Rome II diagnostic criteria.

METHODS

A modified English version of Talley's bowel disease questionnaire was developed in collaboration with various research teams in accordance with the Rome II criteria. This instrument was translated into the local languages of the following nine Asian regions: China, Hong Kong, Indonesia, Korea, Malaysia, Singapore, Taiwan, Thailand and Vietnam. From September to December 2001, newly enrolled outpatients attending 14 GI or medical clinics in these regions were invited to complete the questionnaire. From these respondents, patients with functional gastrointestinal disorders fulfilling the '12 weeks out of 12 months' criteria were separated for further analysis. Principal component factor analysis with varimax rotation was used to identify symptom clusters or factors. These factors were compared with the existing classification of functional GI diseases derived from the Rome II criteria.

RESULTS

Factor analysis of symptoms from 1012 functional GI patients supported the Rome II classification of the following groups of functional GI disorders: diarrhea-predominant irritable bowel syndrome, functional constipation, functional dyspepsia, functional abdominal pain syndrome, functional heartburn, and functional vomiting. Functional diarrhea was combined with functional anorectal disorders, and globus merged with functional dysphagia into one factor. Some of the functional dyspepsia, abdominal bloating and belching symptoms were loaded into one factor.

CONCLUSIONS

Factor analysis of symptoms from a sample of Asian patients with functional GI disorders partially supported the use of the Rome II classification.

Heterogeneity of symptom pattern, psychosocial factors, and pathophysiological mechanisms in severe functional dyspepsia

BACKGROUND & AIMS

Categorization of functional dyspepsia into subgroups is based on expert opinion according to (dominant) symptoms or on underlying pathophysiological mechanisms. We used an evidence-based approach to the determination of subtypes of functional dyspepsia.

METHODS

Consecutive functional dyspepsia patients were recruited from a tertiary referral center. The following were performed: (1) exploratory (EFA) and confirmatory factor analysis (CFA) of symptom patterns in a large group of patients with functional dyspepsia; (2) external validation of these factors by the determination of their association pattern with physio- and psychopathological mechanisms, and with health-related quality of life and sickness behavior; and (3) cluster analysis of their distribution in this population.

RESULTS

Both EFA and CFA do not support the existence of functional dyspepsia as a homogeneous (unidimensional) condition. A 4-factor model is found to be valid, with differential distribution within the patient population according to cluster analysis. Factor 1 is characterized by nausea, vomiting, early satiety, and weight loss and factor 2 by postprandial fullness and bloating. Both factor 1 and 2 are associated with delayed emptying, but only factor 1 is associated with younger age, female sex, and sickness behavior. Factor 3 is characterized by pain symptoms and associated with gastric hypersensitivity and several psychosocial dimensions including medically unexplained symptoms and health-related quality of life dimensions. Factor 4, characterized by belching, is also associated with hypersensitivity, but is unrelated to psychosocial dimensions.

CONCLUSIONS

In a tertiary care population, functional dyspepsia is a heterogeneous condition characterized by 4 major dimensions differentially associated with psychopathological and physiopathological mechanisms.

Systematic review of the comorbidity of irritable bowel syndrome with other disorders: what are the causes and implications?

BACKGROUND & AIMS

Comorbid or extraintestinal symptoms occur frequently with irritable bowel syndrome and account for up to three fourths of excess health care visits. This challenges the assumption that irritable bowel is a distinct disorder. The aims of this study were to (1) assess comorbidity in 3 areas: gastrointestinal disorders, psychiatric disorders, and nongastrointestinal somatic disorders; and (2) evaluate explanatory hypotheses.

METHODS

The scientific literature since 1966 in all languages cited in Medline was systematically reviewed.

RESULTS

Comorbidity with other functional gastrointestinal disorders is high and may be caused by shared pathophysiological mechanisms such as visceral hypersensitivity. Psychiatric disorders, especially major depression, anxiety, and somatoform disorders, occur in up to 94%. The nongastrointestinal nonpsychiatric disorders with the best-documented association are fibromyalgia (median of 49% have IBS), chronic fatigue syndrome (51%), temporomandibular joint disorder (64%), and chronic pelvic pain (50%).

CONCLUSIONS

Multivariate statistical analyses suggest that these are distinct disorders and not manifestations of a common somatization disorder, but their strong comorbidity suggests a common feature important to their expression, which is most likely psychological. Some models explain the comorbidity of irritable bowel with other disorders by suggesting that each disorder is the manifestation of varying combinations of interacting physiological and psychological factors. An alternative hypothesis is that the irritable bowel diagnosis is applied to a heterogeneous group of patients, some of whom have a predominantly psychological etiology, whereas others have a predominantly biological etiology, and that the presence of multiple comorbid disorders is a marker for psychological influences on etiology.

Neuroendocrinology of stress

Stimuli that are interpreted by the brain as extreme or threatening, regardless of their modality, elicit an immediate stereotypic response characterized by enhanced cognition, affective immobility, vigilance, autonomic arousal and a global catabolic state. The brain's ability to mobilize this so-called stress response is paralleled by activation of corticotropin-releasing hormone (CRH) in several nuclei, including the hypothalamus, amygdala and locus ceruleus, and stimulation of the locus ceruleus norepinephrine (LC/NE) system in the brain stem. These systems perpetuate one another, interact with several other transmitter systems in the brain and directly activate the hypothalamic-pituitary-adrenal (HPA) axis and the three components of the autonomic nervous system, namely the sympatho-adrenal, the cranio-sacral parasympathetic and the enteric nervous systems. The widespread body system responses to stress are discussed, and the implications of aberrant stress system activity on physical and mental health are outlined. Moreover, the promise of nonpeptide CRH type-1 receptor antagonists to directly target the stress system in the brain is highlighted.

Artichoke leaf extract reduces symptoms of irritable bowel syndrome in a post-marketing surveillance study

Irritable bowel syndrome (IBS) is a problem reported to affect 22% of the general population. It is characterized by abdominal pain and altered bowel habit, but has so far defied elucidation of its pathogenesis and proved difficult to treat. There is a growing body of evidence which indicates therapeutic properties for artichoke leaf extract (ALE). Dyspepsia is the condition for which the herb is specifically indicated, but the symptom overlap between dyspeptic syndrome and IBS has given rise to the notion that ALE may have potential for treating IBS as well. A sub-group of patients with IBS symptoms was therefore identified from a sample of individuals with dyspeptic syndrome who were being monitored in a post-marketing surveillance study of ALE for 6 weeks. Analysis of the data from the IBS sub-group revealed significant reductions in the severity of symptoms and favourable evaluations of overall effectiveness by both physicians and patients. Furthermore, 96% of patients rated ALE as better than or at least equal to previous therapies administered for their symptoms, and the tolerability of ALE was very good. These results provide support for the notion that ALE has potential value in relieving IBS symptoms and suggest that a controlled trial is justified.

Patient subgroups in irritable bowel syndrome that can be defined by symptom evaluation and physical examination

Subgroups of patients with irritable bowel syndrome (IBS) are likely to respond differently to existing and evolving therapies. The following criteria for subgrouping may be considered: (1) Patients with different predominant bowel habits respond differently to treatment (antidepressants, 5HT3-antagonists, psychotherapy). (2) Postprandial exacerbation of pain or other gastrointestinal symptoms is seen in approximately half of patients with IBS and may identify patients who are more responsive to some classes of drugs (e.g., those targeted at motility). (3) Women appear to respond differently from men to 5HT3-antagonists, and there may be gender differences in gastrointestinal physiology. (4) There is more overlap in the diagnosis of functional dyspepsia and IBS than would be predicted by chance, and both are associated with hyperalgesia to intraluminal distention.