The burden of illness of irritable bowel syndrome: current challenges and hope for the future

Capsaicin-sensitive vagal afferent neurons contribute to the detection of pathogenic bacterial colonization in the gut

Vagal activation can reduce inflammation and disease activity in various animal models of intestinal inflammation via the cholinergic anti-inflammatory pathway. In the current model of this pathway, activation of descending vagal efferents is dependent on a signal initiated by stimulation of vagal afferents. However, little is known about how vagal afferents are activated, especially in the context of subclinical or clinical pathogenic bacterial infection. To address this question, we first determined if selective lesions of capsaicin-sensitive vagal afferents altered c-Fos expression in the nucleus of the solitary tract (nTS) after mice were inoculated with either Campylobacter jejuni or Salmonella typhimurium. Our results demonstrate that the activation of nTS neurons by intraluminal pathogenic bacteria is dependent on intact, capsaicin sensitive vagal afferents. We next determined if inflammatory mediators could cause the observed increase in c-Fos expression in the nTS by a direct action on vagal afferents. This was tested by the use of single-cell calcium measurements in cultured vagal afferent neurons. We found that tumor necrosis factor alpha (TNFα) and lipopolysaccharide (LPS) directly activate cultured vagal afferent neurons and that almost all TNFα and LPS responsive neurons were sensitive to capsaicin. We conclude that activation of the afferent arm of the parasympathetic neuroimmune reflex by pathogenic bacteria in the gut is dependent on capsaicin sensitive vagal afferent neurons and that the release of inflammatory mediators into intestinal tissue can be directly sensed by these neurons.

Early life adversity as a risk factor for visceral pain in later life: importance of sex differences

A history of early life adversity (ELA) has health-related consequences that persist beyond the initial maltreatment and into adulthood. Childhood adversity is associated with abnormal glucocorticoid signaling within the hypothalamic-pituitary-adrenal (HPA) axis and the development of functional pain disorders such as the irritable bowel syndrome (IBS). IBS and many adult psychopathologies are more frequently diagnosed in women, and ovarian hormones have been shown to modulate pain sensitivity. Therefore, the sexually dimorphic effects of ELA and the role of ovarian hormones in visceral pain perception represent critical research concepts to enhance our understanding of the etiology of IBS. In this review, we discuss current animal models of ELA and the potential mechanisms through which ovarian hormones modulate the HPA axis to alter nociceptive signaling pathways and induce functionally relevant changes in pain behaviors following ELA.

A review of the clinical efficacy of linaclotide in irritable bowel syndrome with constipation

OBJECTIVES

The aims were: firstly, to review the definition and diagnosis of irritable bowel syndrome with constipation (IBS-C, a subtype of IBS); secondly, to critically assess current therapies for IBS-C with a focus on effectiveness for abdominal pain; and thirdly, to review clinical studies evaluating the efficacy of linaclotide, a therapy recently approved by the US Food and Drug Administration for the treatment of adults with IBS-C and chronic idiopathic constipation and the European Medicines Agency for the symptomatic treatment of moderate to severe IBS-C in adults, and in development for treatment of IBS-C worldwide.

METHODS

A comprehensive literature review was performed to summarize IBS-C and current treatments. MEDLINE and gastrointestinal society congress proceedings were searched to identify data from linaclotide clinical studies in adults with IBS-C published between January 2010 and August 2012.

RESULTS

IBS-C patients have chronic, relapsing symptoms. Rome III diagnostic criteria define the presence of chronic abdominal pain that improves with defecation and has onset associated with changes in stool frequency or form as a key element of IBS-C and other IBS subtypes. IBS-C patients generally are not completely satisfied with existing therapies. A therapy that treats bowel and abdominal symptoms effectively and can be taken safely on a chronic basis is a current unmet need for IBS-C patients. The guanylate cyclase-C agonist linaclotide has been shown to reduce visceral hypersensitivity in preclinical studies and to improve abdominal pain and constipation symptoms in phase 2 and 3 clinical trials of IBS-C patients.

CONCLUSIONS

IBS-C is a functional gastrointestinal disorder with chronic, relapsing abdominal and constipation symptoms. By virtue of its effects in relieving abdominal pain by reducing visceral hypersensitivity and improving constipation symptoms by increasing intestinal secretion and accelerating transit, linaclotide may be uniquely positioned for a role in the management of IBS-C patients.

A 12-week, randomized, controlled trial with a 4-week randomized withdrawal period to evaluate the efficacy and safety of linaclotide in irritable bowel syndrome with constipation

OBJECTIVES

Linaclotide is a minimally absorbed guanylate cyclase-C agonist. The objective of this trial was to determine the efficacy and safety of linaclotide in patients with irritable bowel syndrome with constipation (IBS-C).

METHODS

This phase 3, double-blind, parallel-group, placebo-controlled trial randomized IBS-C patients to placebo or 290 μ g oral linaclotide once daily in a 12-week treatment period, followed by a 4-week randomized withdrawal (RW) period. There were four primary end points, the Food and Drug Administration ’ s (FDA ’ s) primary end point for IBS-C (responder: improvement of ≥ 30 % in average daily worst abdominal pain score and increase by ≥ 1 complete spontaneous bowel movement (CSBM) from baseline (same week) for at least 50 % of weeks assessed) and three other primary end points, based on improvements in abdominal pain and CSBMs for 9 / 12 weeks. Adverse events (AEs) were monitored.

RESULTS

The trial evaluated 800 patients (mean age = 43.5 years, female = 90.5 % , white = 76.9 % ). The FDA end point was met by 136 / 405 linaclotide-treated patients (33.6 % ), compared with 83 / 395 placebo-treated patients (21.0 % ) ( P < 0.0001) (number needed to treat: 8.0, 95 % confidence interval: 5.4, 15.5). A greater percentage of linaclotide patients, compared with placebo patients, reported for at least 6 / 12 treatment period weeks, a reduction of ≥ 30 % in abdominal pain (50.1 vs. 37.5 % , P = 0.0003) and an increase of ≥ 1 CSBM from baseline (48.6 vs. 29.6 % , P < 0.0001). A greater percentage of linaclotide patients vs. placebo patients were also responders for the other three primary end points ( P < 0.05). Significantly greater improvements were seen in linaclotide vs. placebo patients for all secondary end points ( P < 0.001). During the RW period, patients remaining on linaclotide showed sustained improvement; patients re-randomized from linaclotide to placebo showed return of symptoms, but without worsening of symptoms relative to baseline. Diarrhea, the most common AE, resulted in discontinuation of 5.7 % of linaclotide and 0.3 % of placebo patients.

CONCLUSIONS

Linaclotide significantly improved abdominal pain and bowel symptoms associated with IBS-C for at least 12 weeks; there was no worsening of symptoms compared with baseline following cessation of linaclotide during the RW period.

Food patch testing for irritable bowel syndrome

BACKGROUND

The traditional classification of irritable bowel syndrome (IBS) as a functional disorder has been challenged in recent years by evidence of ongoing low-grade gastrointestinal tract inflammation. Inflammation may alter gastrointestinal motility and thus be central to the pathogenesis of IBS. Many foods and food additives are known to cause allergic contact dermatitis. We hypothesize that allergenic foods and food additives may elicit a similar allergic reaction in the gastrointestinal tract, giving rise to symptoms suggestive of IBS.

OBJECTIVE

We sought to determine whether skin patch testing to a panel of foods and food additives may identify food allergens that may be responsible for symptoms of IBS.

METHODS

We performed skin patch testing to common allergenic foods and food additives on individuals with a history of or symptoms suggestive of IBS. We used patch test-guided avoidance diets to determine whether avoidance alleviates IBS symptoms.

RESULTS

Thirty of the 51 study participants showed at least 1 doubtful or positive patch test result. Fourteen of the participants reported symptomatic improvement, ranging from slight to great, upon avoidance of the foods/food additives to which they reacted.

LIMITATIONS

Double-blind study design, inclusion of only patients with active IBS, larger sample size, more balanced gender distribution, testing of more foods/food additives, and longer duration of and more precise quantification of response to dietary avoidance are suggested for future studies.

CONCLUSION

Allergic contact enteritis to ingested foods, food additives, or both may contribute to IBS symptoms. Patch testing may be useful in identifying the causative foods.

Irritable bowel syndrome: Physicians' awareness and patients' experience

AIM: To study if and how physicians use the irritable bowel syndrome (IBS) diagnostic criteria and to assess treatment strategies in IBS patients.

METHODS: A questionnaire was sent to 191 physicians regarding IBS criteria, diagnostic methods and treatment. Furthermore, 94 patients who were diagnosed with IBS underwent telephone interview.

RESULTS: A total of 80/191 (41.9%) physicians responded to the survey. Overall, 13 patients were diagnosed monthly with IBS by specialists in gastroenterology (SGs) and 2.5 patients by general practitioners (GPs). All the SGs knew of the criteria to diagnose IBS, as did 46/70 (65.7%) GPs. Seventy-nine percent used the patient’s history, 38% used a physical examination, and 38% exclusion of other diseases to diagnose IBS. Only 18/80 (22.5%) physicians used specific IBS criteria. Of the patients interviewed, 59/94 (62.8%) knew they had experienced IBS. Two out of five patients knew IBS and had seen a physician because of IBS symptoms. Half of those received a diagnosis of IBS. A total of 13% were satisfied with treatment. IBS affected daily activities in 43% of cases.

CONCLUSION: Half of the patients with IBS who consulted a physician received a diagnosis. Awareness and knowledge of diagnostic criteria for IBS differ between SGs and GPs.

JCM-16021, a Chinese Herbal Formula, Attenuated Visceral Hyperalgesia in TNBS-Induced Postinflammatory Irritable Bowel Syndrome through Reducing Colonic EC Cell Hyperplasia and Serotonin Availability in Rats

The present study aimed to investigate the analgesic effect of JCM-16021, a revised traditional Chinese herbal formula, on postinflammatory irritable bowel syndrome (PI-IBS) in rats. The trinitrobenzene sulfonic (TNBS) acid-induced PI-IBS model rats were orally administrated with different doses of JCM-16021 (1.2, 2.4, and 4.8 g/kg/d) for 14 consecutive days. The results showed that JCM-16021 treatment dose-dependently attenuated visceral hyperalgesia in PI-IBS rats. Further, the colonic enterochromaffin (EC) cell number, serotonin (5-HT) content, tryptophan hydroxylase expression, and mechanical-stimuli-induced 5-HT release were significantly ameliorated. Moreover, the decreased levels of mucosal cytokines in PI-IBS, especially the helper T-cell type 1- (T(h)1-) related cytokine TNF-α, were also elevated after JCM-16021 treatment. These data demonstrate that the analgesic effect of JCM-16021 on TNBS-induced PI-IBS rats may be medicated via reducing colonic EC cell hyperplasia and 5-HT availability.

Effects of β-(1,3-1,6)-D-glucan on irritable bowel syndrome-related colonic hypersensitivity

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by chronic abdominal pain associated with altered bowel habits. Since the prevalence of IBS is very high and thus, involves elevated health-care costs, treatment of this condition by methods other than prescribed medicines could be beneficial. β-(1,3)-D-glucan with β-(1,6) branches (β-glucan) has been used as a nutritional supplement for many years. In this study, we examined the effect of β-glucan on fecal pellet output and visceral pain response in animal models of IBS. Oral administration of β-glucan suppressed the restraint stress- or drug-induced fecal pellet output. β-Glucan also suppressed the visceral pain response to colorectal distension. These results suggest that β-glucan could be beneficial for the treatment and prevention of IBS.

Differential involvement of amygdala corticosteroid receptors in visceral hyperalgesia following acute or repeated stress

Symptoms of irritable bowel syndrome (IBS) are exacerbated by stress. Previously, we demonstrated that the stress hormone corticosterone applied directly to the amygdala induced visceral hypersensitivity through the actions of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). However, the involvement of amygdaloid GR and MR in the regulation of visceral sensitivity following psychological stress is unknown; therefore, the goal of the present study was to determine the relative importance of amygdaloid GR and MR in the regulation of visceral sensitivity in a rodent model of behavioral stress. Male F-344 rats were stereotaxically implanted with micropellets bilaterally on the dorsal margin of the amygdala containing the GR antagonist mifepristone, the MR antagonist spironolactone, or cholesterol as a control. Animals were then exposed to 1 h of water-avoidance stress (WAS) or sham stress for 1 day (acute) or 7 days (repeated). Visceral sensitivity was assessed either 1 h or 24 h after the final session of WAS and quantified as the number of contractions of the external abdominal oblique, a visceromotor response, in response to colorectal distension at pressures of 0-60 mmHg. Acute stress induced transient visceral hyperalgesia, which was absent 24 h after WAS and independent of GR and MR. Conversely, repeated WAS induced sustained visceral hyperalgesia that was abolished by specifically targeting the amygdala with GR and MR antagonists. These results demonstrate that the amygdala corticosteroid system plays an essential role in mediating the effects of repeated WAS on visceral sensitivity. Furthermore, our findings suggest that amygdaloid GR and MR may be involved in IBS symptomatology.

Knowledge, attitudes, and practices of primary care physicians about irritable bowel syndrome in Northern Saudi Arabia

BACKGROUND/AIM

Primary health care (PHC) physicians manage most patients with irritable bowel syndrome (IBS). In Saudi Arabia, there are limited data on their knowledge, attitudes, and practices about this disorder. This study aimed to assess knowledge, attitudes, and practices of primary care physicians about IBS.

PATIENTS AND METHODS

A cross-sectional survey of 70 practitioners aged 36 ± 10.25 years was carried out in primary care centers in AlJouf Province of Saudi Arabia. The physicians were asked to fill a valid questionnaire containing their sociodemographic data, and well-modified questions regarding their knowledge, attitudes, and practices about IBS. Data was processed and analyzed using SPSS (version 15) program, and the level of significance was set at P<0.05.

RESULTS

A response rate of 92.9% yielded 65 questionnaires for analysis. Majority of physicians surveyed (83.1%) considered IBS as a common health problem in Saudi Arabia, and (55.4%) believed it is underestimated. There was a significant association between physicians' qualifications and using diagnostic tools to facilitate IBS diagnosis (14.3% vs 35.5%; P<0.05), while utilization of "Rome or Manning criteria" was more frequent by physicians with master's degree (35.5%) compared to residents (14.3%). Also, 35.4% of physicians (15 males and 8 females) were not sure how to diagnose IBS.

CONCLUSIONS

This study suggested that PHC physicians had a suitable attitude toward IBS, but they lacked knowledge, and their practices toward this condition were inappropriate.

Small intestinal bacterial overgrowth and lactose intolerance contribute to irritable bowel syndrome symptomatology in Pakistan

BACKGROUND /AIM: The symptoms of irritable bowel syndrome resemble those of small intestinal bacterial overgrowth (SIBO). The aim of this study was to determine the frequency of SIBO and lactose intolerance (LI) occurrence in patients with diarrhea-predominant irritable bowel syndrome (IBS-D) according to Rome III criteria.

PATIENTS AND METHODS

In this retrospective case-control study, patients over 18 years of age with altered bowel habit, bloating, and patients who had lactose Hydrogen breath test (H 2 BT) done were included. The "cases" were defined as patients who fulfill Rome III criteria for IBS-D, while "controls" were those having chronic nonspecific diarrhea (CNSD) who did not fulfill Rome III criteria for IBS-D. Demographic data, predominant bowel habit pattern, concurrent use of medications, etc., were noted.

RESULTS

Patients with IBS-D were 119 (51%) with a mean age of 35 ± 13 years, while those with CNSD were 115 (49%) with mean age 36 ± 15 years. Patients in both IBS-D and CNSD were comparable in gender, with male 87 (74%) and female 77 (64%). SIBO was documented by lactose H₂BT in 32/234 (14%) cases. It was positive in 22/119 (19%) cases with IBS-D, while 10/115 (9%) cases had CNSD (P = 0.03). LI was positive in 43/234 (18%) cases. Of these, 25/119 (21%) cases had IBS-D and 18/115 (16%) cases had CNSD (P = 0.29).

CONCLUSION

SIBO was seen in a significant number of our patients with IBS-D. There was no significant age or gender difference in patients with or without SIBO.

Impact of chronic constipation on health-related quality of life, work productivity, and healthcare resource use: an analysis of the National Health and Wellness Survey

BACKGROUND

There has been limited research addressing the effects of constipation on work productivity and healthcare resource use.

AIMS

To assess the effect of chronic constipation on health outcomes and healthcare resource use.

METHODS

Using data from the 2007 National Health and Wellness Survey (NHWS), chronic constipation patients (n = 1,430) were propensity score-matched to controls (n = 1,430) on demographic and clinical characteristics. Differences between groups in health-related quality of life (SF-12v2), work productivity and activity impairment, and resource use in the last 6 months were examined. Mediation analyses were conducted in order to determine whether the relationship between constipation and resource use was caused by a reduction in health status.

RESULTS

Chronic constipation patients reported significantly lower levels of health-related quality of life (physical component summary score: 39.57 vs. 43.73; mental component summary score: 43.19 vs. 47.86, all P-values < 0.01) and significantly higher levels of loss of work productivity and activity impairment (absenteeism: 9.08% vs. 5.20%; presenteeism: 29.52% vs. 19.09%; overall work impairment: 33.65% vs. 21.56%; activity impairment: 46.58% vs. 33.90%, all P-values < 0.01) compared to the matched controls. Chronic constipation patients also reported significantly more provider (7.73 vs. 5.63) and emergency room visits (0.52 vs. 0.30) in the past 6 months (all P-values < 0.01). Mediation analyses suggested that increased resource use among chronic constipation patients were partially a result of reduced health status.

CONCLUSIONS

Compared to matched controls, chronic constipation patients reported greater economic and humanistic burden. Alleviating the humanistic burden associated with constipation may have economic benefits.

All-cause health care charges among managed care patients with constipation and comorbid irritable bowel syndrome

OBJECTIVE

Chronic idiopathic constipation and irritable bowel syndrome (IBS) are common gastrointestinal conditions with potentially significant burden on managed care systems. Our objective was to examine all-cause resource utilization and charges associated with constipation alone (C-only) and with IBS with comorbid constipation (IBS+C).

METHODS

Administrative claims from a US health plan between January 1, 2003 and December 31, 2005 were analyzed. Patients with C-only (n = 48 585) and IBS+C (n = 10 952) were identified using International Classification of Diseases, 9th Revision, Clinical Modification diagnosis codes. Outcomes were compared with demographically matched controls and with a benchmark group of patients with migraine (N = 48 759). An index date was defined as the date 3 months prior to first observed diagnosis of the condition of interest. Outcomes were evaluated over a 12-month period before and after the index date.

RESULTS

The pre-to-post increase in total charges for subjects with C-only was substantially higher than that for the comparison group ($8837 vs $1717; P < 0.001) or the migraine group ($8837 vs $ 4804; P < 0.001). Subjects with IBS+C also had a greater pre-to-post increase in total charges than did comparison group members ($6192 vs $1319; P < 0.001) and subjects with migraine ($6192 vs $4804; P = 0.0120).

CONCLUSIONS

Both C-only and IBS+C impose substantial economic burden on third-party payers.

Functional abdominal pain and irritable bowel syndrome in children and adolescents

Functional abdominal pain (FAP) and irritable bowel syndrome (IBS) are both associated with recurrent abdominal pain and are among the most commonly diagnosed medical problems in pediatrics. The majority of patients with mild complaints improve with reassurance and time. For a distinct subset of patients with more severe and disabling illness, finding effective treatment for these disorders remains a challenge. Based on the biopsychosocial model of functional disease, the Rome III criteria have helped frame FAP and IBS in terms of being a positive diagnosis and not a diagnosis of exclusion. However, the lack of a single, proven intervention highlights the complex interplay of pathologic mechanisms likely involved in the development of childhood FAP and IBS and the need for a multidisciplinary, integrated approach. This article discusses the epidemiology, proposed mechanisms, clinical approach and therapeutic options for the management of FAP and IBS in children and adolescents.

Genetic risk factors for post-infectious irritable bowel syndrome following a waterborne outbreak of gastroenteritis

BACKGROUND & AIMS

Acute gastroenteritis is the strongest risk factor for irritable bowel syndrome (IBS). In May 2000, >2300 residents of Walkerton, Ontario, developed gastroenteritis from microbial contamination of the municipal water supply; a longitudinal study found that >36.2% of these developed IBS. We used this cohort to study genetic susceptibility to post-infectious (PI)-IBS.

METHODS

We screened 79 functional variants of genes with products involved in serotoninergic pathways, intestinal epithelial barrier function, and innate immunity and performed fine mapping in regions of interest. We compared data from Walkerton residents who developed gastroenteritis and reported PI-IBS 2 to 3 years after the outbreak (n = 228, cases) with data from residents who developed gastroenteritis but did not develop PI-IBS (n = 581, controls).

RESULTS

Four variants were associated with PI-IBS, although the association was not significant after correction for the total number of single nucleotide polymorphisms. Two were located in TLR9, which encodes a pattern recognition receptor (rs352139, P545P; P = .0059 and rs5743836, -T1237C; P = .0250; r(2) < 0.14); 1 was in CDH1, which encodes a tight junction protein (rs16260, -C160A; P = .0352); and 1 was in IL6, which encodes a cytokine (rs1800795, -G174C; P = .0420). Denser mapping of these 3 regions revealed 1 novel association in IL6 (rs2069861; P = .0069) and 14 associations that could be accounted for by linkage disequilibrium with the 4 original variants. The TLR9, IL6, and CDH1 variants all persisted as independent risk factors for PI-IBS when controlling for previously identified clinical risk factors.

CONCLUSION

This is the first descriptive study to assess potential genetic determinants of PI-IBS. Genes that encode proteins involved in epithelial cell barrier function and the innate immune response to enteric bacteria are associated with development of IBS following acute gastroenteritis.

Small intestinal bacterial overgrowth in irritable bowel syndrome: are there any predictors?

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is a condition in which excessive levels of bacteria, mainly the colonic-type species are present in the small intestine. Recent data suggest that SIBO may contribute to the pathophysiology of Irritable bowel syndrome (IBS). The purpose of this study was to identify potential predictors of SIBO in patients with IBS.

METHODS

Adults with IBS based on Rome II criteria who had predominance of bloating and flatulence underwent a glucose breath test (GBT) to determine the presence of SIBO. Breath samples were obtained at baseline and at 30, 45, 60, 75 and 90 minutes after ingestion of 50 g of glucose dissolved in 150 mL of water. Results of the glucose breath test, which measures hydrogen and methane levels in the breath, were considered positive for SIBO if 1) the hydrogen or methane peak was >20 ppm when the baseline was <10 ppm, or 2) the hydrogen or methane peak increased by 12 ppm when baseline was >or=10 ppm.

RESULTS

Ninety-eight patients were identified who underwent a GBT (mean age, 49 y; 78% female). Thirty-five patients (36%) had a positive GBT result suggestive of SIBO. A positive GBT result was more likely in patients >55 years of age (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.4-9.0) and in females (OR, 4.0; 95% CI, 1.1-14.5). Hydrogen was detected more frequently in patients with diarrhea-predominant IBS (OR, 8; 95% CI, 1.4-45), and methane was the main gas detected in patients with constipation-predominant IBS (OR, 8; 95% CI, 1.3-44). There was no significant correlation between the presence of SIBO and the predominant bowel pattern or concurrent use of tegaserod, proton pump inhibitors, or opiate analgesics.

CONCLUSIONS

Small intestinal bacterial overgrowth was present in a sizeable percentage of patients with IBS with predominance of bloating and flatulence. Older age and female sex were predictors of SIBO in patients with IBS. Identification of possible predictors of SIBO in patients with IBS could aid in the development of successful treatment plans.

Quality of life and sugar and fiber intake in women with irritable bowel syndrome

The purpose of this study is to examine quality of life (QOL) and dietary constituents in three subgroups of women with irritable bowel syndrome (IBS) based on the severity of their bloating symptoms. A secondary analysis of data from two studies of women with IBS (n = 183), ages 18 to 48, is performed. Measures include the Modified Flanagan Quality of Life Scale and a 3-day food record ( n = 95) and a daily symptom diary completed over a month. There are no differences in QOL and few differences in dietary intake, although women with the most severe bloating report less dietary intake of fructose ( p = .035) as compared with the women with less severe bloating symptoms. The findings suggest that women with IBS who experience moderate to severe bloating symptoms may not reduce their dietary intake except fructose.

The putative role of the intestinal microbiota in the irritable bowel syndrome

The irritable bowel syndrome (IBS) is a chronic abdominal symptom complex that is heterogeneous in terms of its clinical presentation and underlying pathophysiology and pathogenesis. It is now established that enteric infection can trigger the syndrome in at least a subset of patients. In addition, there is growing evidence of low grade inflammation and immune activation in the distal bowel of some IBS patients. These observations now prompt the question as to what maintains gut dysfunction in these patients. The intestinal microbiota influences a broad array of host organs that include the gut and the brain, and is an important determinant of normal function in these systems. Disruption of the delicate balance between the host and its intestinal microbiota (termed dysbiosis) results in changes in the mucosal immune system that range from overt inflammation as seen in Crohn's Disease, to low grade inflammation without tissue injury, as seen in a subset of IBS patients. Under experimental conditions, disruption of the microbiota also produces changes in gut sensory-motor function and immune activity. Thus, dysbiosis induced by infection, dietary change or drugs such as antibiotics could produce low grade inflammation and chronic gut dysfunction, reminiscent of that seen in IBS. Fluctuations in gut physiology destabilize the habitat of commensal bacteria and provide a basis for chronic dysbiosis. Recent observations in animal models that changes in gut flora influence behavior provide a basis for a novel unifying hypothesis that accommodates both gut dysfunction and behavioral changes that characterize many IBS patients. This hypothesis states that dysbiosis exists in at least a subset of IBS patients, as a result of infection, dietary change or drugs and contributes to gut inflammatory and functional change in addition to psychiatric co-morbidity.

Symptom management for irritable bowel syndrome: a pilot randomized controlled trial of acupuncture/moxibustion

The purpose of this pilot study was to assess the effect of an individualized traditional Chinese medicine (TCM) acupuncture and moxibustion (Acu/Moxa) treatment on symptom control in patients with irritable bowel syndrome (IBS) in a preliminary, randomized, sham/placebo-controlled trial. Twenty-nine men and women with IBS were randomized to either individualized Acu/Moxa (treatment group) or sham/placebo Acu/Moxa (control group). All subjects were assessed by a diagnostic acupuncturist for a TCM evaluation and individualized point prescription. Only those subjects assigned to the experimental group received the individually prescribed treatment. The diagnostic acupuncturist did not administer treatments and was blind to treatment assignments. All subjects kept a symptom diary for the duration of the study, enabling measurement of symptom frequency, severity, and improvement. The Clinical Global Impression Scale was administered preintervention to establish baseline severity and on completion of the 4-week, eight-session treatment intervention. After 4 weeks of twice-weekly Acu/Moxa treatment, average daily abdominal pain/discomfort improved whereas the control group showed minimal reduction. This between-group difference adjusted for baseline difference was statistically significant. The intestinal gas, bloating, and stool consistency composite score showed a similar pattern of improvement. The findings indicate that Acu/Moxa treatment shows promise in the area of symptom management for IBS.

Role of anxiety in the pathophysiology of irritable bowel syndrome: importance of the amygdala

A common characteristic of irritable bowel syndrome (IBS) is that symptoms, including abdominal pain and abnormal bowel habits, are often triggered or exacerbated during periods of stress and anxiety. However, the impact of anxiety and affective disorders on the gastrointestinal (GI) tract is poorly understood and may in part explain the lack of effective therapeutic approaches to treat IBS. The amygdala is an important structure for regulating anxiety with the central nucleus of the amygdala facilitating the activation of the hypothalamic-pituitary-adrenal axis and the autonomic nervous system in response to stress. Moreover, chronic stress enhances function of the amygdala and promotes neural plasticity throughout the amygdaloid complex. This review outlines the latest findings obtained from human studies and animal models related to the role of the emotional brain in the regulation of enteric function, specifically how increasing the gain of the amygdala to induce anxiety-like behavior using corticosterone or chronic stress increases responsiveness to both visceral and somatic stimuli in rodents. A focus of the review is the relative importance of mineralocorticoid receptor and glucocorticoid receptor-mediated mechanisms within the amygdala in the regulation of anxiety and nociceptive behaviors that are characteristic features of IBS. This review also discusses several outstanding questions important for future research on the role of the amygdala in the generation of abnormal GI function that may lead to potential targets for new therapies to treat functional bowel disorders such as IBS.

Use of serum biomarkers in a diagnostic test for irritable bowel syndrome

BACKGROUND

Currently, no single serum biomarker can reliably differentiate irritable bowel syndrome (IBS) from other functional gastrointestinal disorders or organic diseases of the gastrointestinal tract.

AIM

To develop and validate a diagnostic test using serum biomarkers to detect IBS.

METHODS

Ten serum biomarkers were selected from a potential panel of 140 for their ability to differentiate IBS from non-IBS disease in blood samples from patients with IBS, other gastrointestinal disorders and healthy volunteers. A predictive modelling tool was developed to assess patterns and relationships among the 10 serum biomarkers that best differentiated IBS patients from healthy controls and patients with non-IBS gastrointestinal disease. This model was tested in a different cohort of patients and healthy controls (n = 516) to determine the predictive accuracy of differentiating IBS from non-IBS.

RESULTS

The sensitivity and specificity of the 10-biomarker algorithm for differentiating IBS from non-IBS was 50% and 88% respectively. The positive predictive value was 81%, and the negative predictive value was 64% at 50% IBS prevalence in the validation cohort. Overall accuracy was 70%.

CONCLUSIONS

Assessing serum biomarker patterns can differentiate IBS from non-IBS with reasonable sensitivity and specificity. Assessing serum biomarkers in an overall diagnostic strategy may allow earlier diagnosis and treatment for patients with IBS.

Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection

Blastocystis is a prevalent enteric protozoan that infects a variety of vertebrates. Infection with Blastocystis in humans has been associated with abdominal pain, diarrhea, constipation, fatigue, skin rash, and other symptoms. Researchers using different methods and examining different patient groups have reported asymptomatic infection, acute symptomatic infection, and chronic symptomatic infection. The variation in accounts has lead to disagreements concerning the role of Blastocystis in human disease, and the importance of treating it. A better understanding of the number of species of Blastocystis that can infect humans, along with realization of the limitations of the existing clinical laboratory diagnostic techniques may account for much of the disagreement. The possibility that disagreement was caused by the emergence of particular pathogenic variants of Blastocystis is discussed, along with the potential role of Blastocystis infection in irritable bowel syndrome (IBS). Findings are discussed concerning the role of protease-activated receptor-2 in enteric disease which may account for the presence of abdominal pain and diffuse symptoms in Blastocystis infection, even in the absence of fever and endoscopic findings. The availability of better diagnostic techniques and treatments for Blastocystis infection may be of value in understanding chronic gastrointestinal illness of unknown etiology.

Neural and psychological predictors of treatment response in irritable bowel syndrome patients with a 5-HT3 receptor antagonist: a pilot study

BACKGROUND

Symptom improvement in irritable bowel syndrome (IBS) treatment trials varies widely, with only 50-70% of patients qualifying as responders. Factors predicting treatment responsiveness are not known, although we have demonstrated that symptom improvement with the 5-HT3R antagonist alosetron is correlated with reduced amygdala activity.

AIM

To determine whether neural activity during rectal discomfort or psychological distress predicts symptom improvement following treatment with alosetron.

METHODS

Basal psychological distress and neural activity (15O PET) during uncomfortable rectal stimulation were measured in 17 nonconstipated IBS patients who then received 3 weeks of alosetron treatment.

RESULTS

Greater symptom improvement was predicted by less activity in bilateral orbitofrontal cortex (OFC) and medial temporal gyrus during pre-treatment scans. Lower levels of interpersonal sensitivity predicted greater symptom improvement and were positively related to activity in left OFC. Connectivity analysis revealed a positive relationship between activity in the left OFC and right amygdala.

CONCLUSIONS

Irritable bowel disease symptom improvement with 5-HT3R antagonist alosetron is related to pre-treatment reactivity of the left OFC, which may be partially captured by subjective measures of interpersonal sensitivity. The left OFC may fail to modulate amygdala response to visceral stimulation, thereby diminishing effectiveness of treatment. Psychological factors and their neurobiological correlates are plausible predictors of IBS treatment outcome.

Multidimensionality of symptom complexes in irritable bowel syndrome and other functional gastrointestinal disorders

The definition of irritable bowel syndrome (IBS) by Rome criteria was a major advancement in the nosology of the disease, but this goal was achieved by employing symptoms related to the gastrointestinal tract and by eliminating all symptoms that were nonspecific. The description of the course of the illness and response to treatment has been hampered by restrictions to the defining characteristics, abdominal pain and altered bowel habit. Other abdominal symptoms (e.g., bloating, nausea, and epigastric discomfort) and general somatic symptoms (e.g., fatigue, headache, and sleep disturbance) are not included in the Rome definition, yet are commonly reported by patients with IBS. This article addresses the following questions: Are comorbid conditions part of or distinct from the syndrome of IBS and other functional gastrointestinal disorders (FGIDs)? Are there overlapping abdominal or extra-abdominal symptoms confounding the definition of IBS? Are extra-abdominal somatic symptoms and/or syndromes part of the clinical presentation of IBS? Are "nondiagnostic" abdominal symptoms important in defining symptom burden in IBS? Is the concept of somatization related to IBS, and, if so, how? How can we better define the symptom burden in IBS and other FGIDs? In short, have we hampered the evaluation of IBS (and other FGIDs) by making the definitions too reductionist? While definite answers to the above questions are not possible at this time, this article proposes that the definitions of IBS or other FGIDs not be altered, but that in the process of evaluation of the clinical end points and/or severity of the diseases, consideration be given to the possibility of including other components of the symptom burden of these disorders.

Updates on treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder characterized by abdominal pain and discomfort in association with altered bowel habits. It is estimated to affect 10%-15% of the Western population, and has a large impact on quality of life and (in)direct healthcare costs. IBS is a multifactorial disorder involving dysregulation within the brain-gut axis, and it is frequently associated with gastrointestinal motor and sensory dysfunction, enteric and central nervous system irregularities, neuroimmune dysregulation, and post-infectious inflammation. As with other functional medical disorders, the treatment for IBS can be challenging. Conventional therapy for those with moderate to severe symptoms is largely unsatisfactory, and the development of new and effective drugs is made difficult by the complex pathogenesis, variety of symptoms, and lack of objective clinical findings that are the hallmark of this disorder. Fortunately, research advances over the past several decades have provided insight into potential mechanisms responsible for the pathogenesis of IBS, and have led to the development of several promising pharmaceutical agents. In recent years there has been much publicity over several of these new IBS medications (alosetron and tegaserod) because of their reported association with ischemic colitis and cardiovascular disease. While these agents remain available for use under restricted prescribing programs, this highlights the need for continued development of safe and effective medication for IBS. This article provides a physiologically-based overview of recently developed and frequently employed pharmaceutical agents used to treat IBS, and discusses some non-pharmaceutical options that may be beneficial in this disorder.

Integrative medicine in gastrointestinal disease: evaluating the evidence

Current Western therapies for many gastrointestinal diseases are suboptimal and potentially toxic. The majority of patients with digestive diseases are turning to complementary and alternative medicine for symptom relief and improved quality of life, due to dissatisfaction with conventional medical therapies. There is emerging evidence that many of these complementary and alternative medicine modalities are highly effective in modulating the immune system, disrupting the proinflammatory cascade and restoring digestive health while improving patients' quality of life. We present evidence to support the potential utility of complementary and alternative medicine modalities for irritable bowel syndrome and inflammatory bowel disease. For each condition, we detail the proposed mechanisms of action and explore the current data for the prevention and/or treatment of disease.

Efficacy of on-demand asimadoline, a peripheral kappa-opioid agonist, in females with irritable bowel syndrome

BACKGROUND & AIMS

In experimental animal models of irritable bowel syndrome (IBS) and human studies, peripheral kappa opioid agonists have been shown to decrease sensation to colonic distention. The aim of this study was to compare the effects of the kappa opioid agonist, asimadoline, and placebo on episodes of abdominal pain in patients with IBS.

METHODS

After a 2-week run-in period, 100 patients with IBS were randomized (3:2 ratio) to receive asimadoline, up to 1 mg 4 times daily, or placebo for 4 weeks in a double-blind study. Pain was scored by daily diary using a 100-mm visual analogue scale. During pain episodes, patients recorded the pain severity, took study medication, and recorded their pain score 2 hours later. The primary end point was the average reduction in pain severity 2 hours after treatment.

RESULTS

The average pain reduction 2 hours posttreatment was not significantly different between the groups. Post hoc analyses suggest asimadoline was effective in mixed IBS (P = .003, unadjusted), but may be worse in diarrhea-predominant IBS (P = .065 unadjusted). The anxiety score was reduced modestly by asimadoline (P = .053). No significant adverse effects were noted.

CONCLUSIONS

An on-demand dosing schedule of asimadoline was not effective in reducing severity of abdominal pain in IBS. Further studies in visceral pain and IBS appear warranted.

School nurse knowledge and perceptions of recurrent abdominal pain: opportunity for therapeutic alliance?

Recurrent abdominal pain of childhood affects up to 15% of school-age children, who face significant psychosocial consequences, including school absence. Because assessment of recurrent abdominal pain is frequently made at the school nurse level, a questionnaire was sent to 425 school nurses to evaluate perceptions about recurrent abdominal pain. Among the responses, 47.1% believed children were taking or seeking attention; 3.6% considered it a serious disease, 77.9% stated that affected children should see a physician, 51.5% believed they should relax, and 25.0% believed they needed medicine. Results indicated that school nurses were unclear on epidemiologic and etiologic features of recurrent abdominal pain and had negative views that may inadvertently contribute to the anxiety felt by affected children. Education of school nurses and communication from physicians may advance strategies designed to reduce the fiscal and social costs associated with this common childhood condition.

Psychological distress and impaired quality of life common among community-dwelling adults with lower gastrointestinal disorders

This study examines the comparison of psychological well-being and health-related quality of life (HRQOL) between adults with and without lower gastrointestinal (GI) disorders and between adults with lower GI disorders and those with other common chronic illnesses. Data of adults aged 18 years or older from the 2002 National Health Interview Survey (n=29,828) were analyzed. Approximately 5.4% of survey participants reported they had been told by a physician that they had lower GI disorders. Those reporting lower GI disorders were 1.8 times more likely to meet the criteria for serious mental illness (SMI) and were significantly more likely to report impaired HRQOL than those without GI disorders. In addition, those with lower GI disorders were significantly more likely than those with heart disease and diabetes and equally as likely as those with arthritis and asthma to meet the criteria for SMI. Because psychological comorbidity is common among adults with lower GI disorders and may complicate their course and treatment, clinicians should consider screening patients presenting with lower GI disorders for these comorbid conditions.

A patient follow-up survey programme for alosetron: assessing compliance to and effectiveness of the risk management programme

BACKGROUND

In November 2002, alosetron HCl (Lotronex, GlaxoSmithKline Research Triangle Park, NC, USA) was re-introduced to the US marketplace for women with severe diarrhoea-predominant irritable bowel syndrome. In support of the re-introduction, a risk management programme was implemented, which included a patient follow-up study in which all users of alosetron could participate.

AIM

We report on the methods used and the effectiveness of key elements of the risk management programme.

METHODS

Patients voluntarily enroled in the study and completed questionnaires at baseline, after 5 and 10 weeks, and quarterly thereafter. Questions focussed on patient eligibility, knowledge of risks and benefits, and adherence to the recommended programme elements for education, prescribing and dispensing.

RESULTS

Between December 2002 and 2004, 4,803 patients enrolled in the study, and <3% were lost to follow-up. The average follow-up time was approximately 6 months, and the response rate for each assessment was >95%. A total of 90% of patients at baseline met the full clinical criteria recommended for the treatment. Patient adherence to the risk management programme was >87%.

CONCLUSIONS

Using the Lotronex risk management programme, patients met clinical criteria, were knowledgeable about treatment risks and benefits, and were adherent to the process elements of the programme. These patients seemed to engage in active dialogue with their physicians about symptoms and use of alosetron.

Quality of life of patients with irritable bowel syndrome is low compared to others with chronic diseases

BACKGROUND

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal dysmotility disorder. This study aimed to estimate the burden of illness of a Dutch population of community dwelling patients suffering from IBS.

METHODS

Patients identified at community pharmacies, using mebeverine as a proxy for IBS, were administered a questionnaire regarding (1) the Rome II criteria for IBS, (2) predominant type of stool during complaints, (3) severity of symptoms (abdominal pain and discomfort), (4) generic and disease-specific quality of life, (5) current health status (utilities), and (6) loss of productivity.

RESULTS

Three hundred and seventy-five users of mebeverine were identified of which 169 patients met the Rome II criteria for IBS, and were included in the study. More than half (58%) of the IBS patients reported severe abdominal pain and complaints. Generic and disease-specific quality of life outcomes showed impairment on all dimensions. Current health status in IBS patients, calculated on the basis of the EQ-5D VAS, was perceived on 62% of full health (95% CI, 60-66%). A calculation of health status in these patients based on the SF-6D algorithm showed a comparable score of 0.67 (1 is full health; 95% CI, 0.65-0.68). The loss in productivity of IBS patients was 1.8 days (95% CI, 1.1-2.5) per month.

CONCLUSIONS

This study confirmed that the burden of illness of IBS in the Netherlands is substantial. IBS patients treated with mebeverine experienced low quality of life and suffered from severe pain. Based on these results, more attention for the diagnosis and treatment of IBS seems to be justified.

Health-related quality of life of irritable bowel syndrome patients in different cultural settings

BACKGROUND

Persons with Irritable bowel syndrome (IBS) are seriously affected in their everyday life. The effect across different cultural settings of IBS on their quality of life has been little studied. The aim was to compare health-related quality of life (HRQOL) of individuals suffering from IBS in two different cultural settings; Crete, Greece and Linköping, Sweden.

METHODS

This study is a sex and age-matched case-control study, with n = 30 Cretan IBS cases and n = 90 Swedish IBS cases and a Swedish control group (n = 300) randomly selected from the general population. Health-related quality of life, measured by SF-36 and demographics, life style indicators and co-morbidity, was measured.

RESULTS

Cretan IBS cases reported lower HRQOL on most dimensions of SF-36 in comparison to the Swedish IBS cases. Significant differences were found for the dimensions mental health (p < 0.0001) and general health (p = 0.05) even after adjustments for educational level and co-morbidity. Women from Crete with IBS scored especially low on the dimensions general health (p = 0.009) and mental health (p < 0.0001) in comparison with Swedish women with IBS. The IBS cases, from both sites, reported significantly lower scores on all HRQOL dimensions in comparison with the Swedish control group.

CONCLUSION

The results from this study tentatively support that the claim that similar individuals having the same disease, e.g. IBS, but living in different cultural environments could perceive their disease differently and that the disease might affect their everyday life and quality of life in a different way. The Cretan population, and especially women, are more seriously affected mentally by their disease than Swedish IBS cases. Coping with IBS in everyday life might be more problematic in the Cretan environment than in the Swedish setting.

Patients with irritable bowel syndrome in primary care appear not to be heavy healthcare utilizers

BACKGROUND

Irritable bowel syndrome is a frequently diagnosed gastrointestinal condition in general practice. Managing this chronic condition requires a co-ordinated effort between patient and doctor.

AIM

To explore the patterns of treatment and healthcare utilization of irritable bowel syndrome cases in a Swedish primary care setting.

METHODS

All cases with a registered diagnosis of irritable bowel syndrome were identified retrospectively for a 5-year period through computerized medical records at three primary healthcare centres in Sweden. Documentation of diagnosis, healthcare visits, treatments, investigations, medications, referrals, laboratory tests, mental and demographic data were retrieved from the records.

RESULTS

Of all 723 irritable bowel syndrome patients identified, only 37% had a follow-up appointment to their General Practitioner during the study period. For 80%, the General Practitioner initiated some treatment during the initial consultation and 75% were prescribed medication. Fibre and bulking laxatives and acid-suppressive drugs were the most common medication. Almost a quarter was referred for complementary investigations at hospital, only 8.9% of the irritable bowel syndrome patients were referred to a specialist investigation. Laboratory investigations varied and were ordered more frequently (P = 0.05) for men.

CONCLUSIONS

Irritable bowel syndrome patients appear not to be heavy utilizers of primary care and, of those who attend, the majority are managed by their General Practitioner.

Quality of life for children with functional abdominal pain: a comparison study of patients' and parents' perceptions

OBJECTIVE

Children with chronic abdominal pain of nonorganic origin, termed functional abdominal pain (FAP), experience school absences and social withdrawal and report impaired physical ability. The aim of this study was to assess patients' and parents' perceptions of health-related quality of life (QoL) for children with FAP.

METHODS

Between October 2002 and November 2003, 209 children (including 125 girls; age: 11.2 +/- 3.5 years) and 209 parents were recruited from a pediatric referral center. At the time of their initial evaluations, participants completed a validated, health-related QoL instrument (Pediatric Quality of Life Inventory), which was scored on a scale of 0 (poor) through 100 (best). Children with FAP (n = 65) and their families were compared with control groups of healthy children (n = 46) and children with histologically proven inflammatory bowel disease (IBD) (n = 42) or gastroesophageal reflux disease (GERD) (n = 56).

RESULTS

Children with FAP had self-reported QoL scores (score: 78) that were similar to those for children with GERD (score: 80) or IBD (score: 84). Children with FAP had lower QoL scores than did healthy children (score: 88). Parents of children with FAP reported lower QoL scores, compared with their children's scores (scores: 70 vs 78).

CONCLUSIONS

Children with FAP reported lower QoL, compared with their healthy peers, and had the same QoL scores as did children with IBD or GERD. Parents' perceptions of QoL for children with FAP were lower than their children's self-reported scores. These findings highlight the clinical significance of FAP and may provide insight into one facet of the disease's biopsychosocial etiology.

Irritable bowel syndrome medications side effects survey

OBJECTIVES

This study was conducted to determine the frequency and severity of side effects (SEs) experienced during treatment with standard medications used to treat patients with irritable bowel syndrome (IBS) with constipation (IBS-C).

METHODS

In January of 2002, 668 subjects responded to a survey addressed to an online panel of 25,000 physician-diagnosed IBS sufferers. Of the survey respondents, 504 had constipation as a predominant bowel habit (median age 45 years, and 88% were women). Respondents answered questions about the therapies they used to relieve their IBS symptoms and about any SEs they experienced while taking these therapies; they were also asked to rate their satisfaction with their current/past medications. To gauge IBS impact, respondents were also asked about the number of times they either visited or called their health-care provider about their IBS symptoms and approximately how many days of work or school they missed because of their IBS symptoms.

RESULTS

Subjects reported having tried an average of 3.9 +/- 3.3 medications for their IBS-C symptoms with virtually all subjects (99%) having tried at least 1 medication. Subjects reported an average of 3.3 +/- 2.7 SEs. Nearly three quarters reported discontinuing treatment because of SEs, and many sought medical help or missed work, school, or social activities because of SEs.

CONCLUSIONS

Traditional therapies for IBS-C, including laxatives, fiber, and stool softeners, are associated with SEs that negatively affect the lives of IBS sufferers.