Presentation and Characteristics of Abdominal Pain Vary by Irritable Bowel Syndrome Subtype: Results of a Nationwide Population-Based Study

Intestinal Permeability, Irritable Bowel Syndrome with Constipation, and the Role of Sodium-Hydrogen Exchanger Isoform 3 (NHE3)

Increased intestinal permeability has been identified as one of the many pathophysiological factors associated with the development of irritable bowel syndrome (IBS), a common disorder of gut-brain interaction. The layer of epithelial cells that lines the intestine is permeable to a limited degree, and the amount of paracellular permeability is tightly controlled to enable the absorption of ions, nutrients, and water from the lumen. Increased intestinal permeability to macromolecules can be triggered by a variety of insults, including infections, toxins from food poisoning, or allergens, which in turn cause an inflammatory response and are associated with abdominal pain in patients with IBS. This review article discusses increased intestinal permeability in IBS, focusing on IBS with constipation (IBS-C) through the lens of a patient case with a reported prior diagnosis of "leaky gut syndrome" upon initial contact with a gastrointestinal specialist. We review advantages and disadvantages of several methods of measuring intestinal permeability in patients and discuss when measuring intestinal permeability is appropriate in the therapeutic journey of patients with IBS-C. Furthermore, we discuss a possible mechanism of restoring the intestinal barrier to its healthy state through altering intracellular pH by inhibiting sodium-hydrogen exchanger isoform 3 (NHE3). Tenapanor is a minimally absorbed, small-molecule inhibitor of NHE3 that has been approved by the US Food and Drug Administration for the treatment of IBS-C in adults. Preclinical studies showed that tenapanor may restore the intestinal barrier in IBS-C by affecting the conformation of tight junction proteins via NHE3 inhibition to block the paracellular transport of macromolecules from the intestinal lumen. Testing for increased permeability in patients with IBS-C who experience abdominal pain may help inform the choice of therapeutics and alter patients' misconceptions about "leaky gut syndrome".

Abdominal Symptom Improvement During Clinical Trials of Tenapanor in Patients With Irritable Bowel Syndrome With Constipation: A Post Hoc Analysis

INTRODUCTION

This post hoc analysis evaluated the efficacy of tenapanor on abdominal symptoms in patients with irritable bowel syndrome with constipation. Abdominal symptoms assessed included pain, discomfort, bloating, cramping, and fullness.

METHODS

The abdominal symptom data were pooled from 3 randomized controlled trials (NCT01923428, T3MPO-1 [NCT02621892], and T3MPO-2 [NCT02686138]). Weekly scores were calculated for each abdominal symptom, and the Abdominal Score (AS) was derived as the average of weekly scores for abdominal pain, discomfort, and bloating. The overall change from baseline during the 12 weeks was assessed for each symptom weekly score and the AS. The AS 6/12-week and 9/12-week response rates (AS improvement of ≥2 points for ≥6/12- or ≥9/12-week) were also evaluated. The association of weekly AS response status (reduction of ≥30%) with weekly complete spontaneous bowel movement (CSBM) status (=0 and >0) was assessed.

RESULTS

Among 1,372 patients (684 tenapanor [50 mg twice a day] and 688 placebo), the least squares mean change from baseline in AS was -2.66 for tenapanor vs -2.09 for placebo ( P < 0.0001). The 6/12-week AS response rate was 44.4% for tenapanor vs 32.4% for placebo ( P < 0.0001), and for 9/12-week AS, 30.6% for tenapanor vs 20.5% for placebo ( P < 0.0001). A significant association between weekly CSBM status and weekly AS response status was observed each week ( P < 0.0001), with a greater proportion achieving an AS reduction in patients with >0 CSBMs in a week.

DISCUSSION

Tenapanor significantly reduced abdominal symptoms in patients with irritable bowel syndrome with constipation, particularly pain, discomfort, and bloating measured by AS, compared with placebo.

Severe Multiple Drug Intolerance Syndrome in Fibromyalgia and Irritable Bowel Syndrome

BACKGROUND

Multiple drug intolerance syndrome (MDIS) describes patients with multiple nonimmunologically mediated adverse reactions to medications. Patients with more than 10 medication intolerance labels are considered to have severe MDIS. There is overlap in the characteristics of patients with MDIS and fibromyalgia and irritable bowel syndrome (IBS). Severe MDIS can limit treatment options in this already complex patient group.

OBJECTIVE

This study assessed the prevalence of severe MDIS in patients with fibromyalgia and IBS and its associated risk factors.

METHODS

A retrospective chart review identified patients diagnosed with fibromyalgia or IBS who had been seen at a large academic center from August 2019 to July 2020. Exact birthdate- and sex-matched controls who had been seen within the same time frame were selected at random. Listed drug intolerance data and patient characteristics were then analyzed with logistic regression and χ2 testing.

RESULTS

Patients with fibromyalgia and IBS were 12 and 3 times more likely to have severe MDIS compared with controls, respectively. Severe MDIS was associated with polypharmacy in both groups. Opiates were the most frequently reported drug intolerance across all participants. Although patients with IBS more often reported gastrointestinal symptoms as adverse reactions, individuals with fibromyalgia did not more frequently report pain or behavioral changes as adverse reactions.

CONCLUSIONS

There was an increased rate of severe MDIS in patients diagnosed with fibromyalgia and IBS. Additional studies are needed to better understand the morbidity of MDIS and how it can best be managed in patients with fibromyalgia and IBS.

Plecanatide Improves Symptoms of Irritable Bowel Syndrome with Constipation: Results of an Integrated Efficacy and Safety Analysis of Two Phase 3 Trials

Purpose

Patients with irritable bowel syndrome with constipation (IBS-C) experience abdominal pain with altered bowel movements. Plecanatide is indicated as IBS-C treatment in adults. This integrated analysis further characterizes plecanatide efficacy and safety in IBS-C.

Patients and Methods

Data pooled from 2 identically designed phase 3 trials included adults with IBS-C randomized to plecanatide 3 mg or 6 mg, or placebo once daily for 12 weeks. A daily diary recorded stool frequency/symptoms, with abdominal pain, bloating, cramping, discomfort, fullness, and straining intensity individually rated. Overall response (primary endpoint) was defined as ≥30% improvement from baseline in average worst abdominal pain severity and increase of ≥1 complete spontaneous bowel movement, during same week (composite), for ≥6 of 12 weeks. Secondary endpoints included sustained response (overall response, plus meeting weekly composite criteria during ≥2 of last 4 treatment weeks) and changes from baseline in individual symptoms. Safety assessments included adverse event monitoring.

Results

Overall, 2176 patients (74.0% female; mean [SD] age, 43.5 [14.1] years) were included in efficacy analyses (plecanatide 3 mg [n = 724], 6 mg [n = 723], placebo [n = 729]). A significantly greater percentage of patients achieved overall response with plecanatide 3 mg (25.6%) and 6 mg (26.7%) versus placebo (16.0%; both P < 0.001 vs placebo). A significantly greater percentage of patients were sustained responders with plecanatide 3 mg (24.3%) and 6 mg (25.6%) versus placebo (15.6%; both P < 0.001 vs placebo). Significant improvements from baseline in abdominal discomfort, abdominal fullness, abdominal pain, bloating, and cramping occurred as early as Week 1 (Week 2 for abdominal pain) with plecanatide and were maintained through Week 12 versus placebo. Diarrhea, the most common adverse event, occurred in 4.3% (3 mg), 4.0% (6 mg) and 1.0% (placebo) of patients, leading to study discontinuation in 1.2%, 1.4%, and 0 patients, respectively.

Conclusion

Plecanatide is safe and effective for treating global and individual IBS-C symptoms.

Efficacy and safety of olorinab, a full agonist of the cannabinoid receptor 2, for the treatment of abdominal pain in patients with irritable bowel syndrome: Results from a phase 2b randomized placebo-controlled trial (CAPTIVATE)

BACKGROUND

Olorinab is a highly selective, peripherally acting, full agonist of cannabinoid receptor 2. This study assessed the efficacy and safety of olorinab to treat abdominal pain in patients with irritable bowel syndrome with diarrhea (IBS-D) and constipation (IBS-C).

METHODS

CAPTIVATE was a phase 2b, randomized, double-blind, placebo-controlled, parallel-group trial. Eligible participants aged 18-70 years with IBS-C and IBS-D diagnosed per Rome IV received olorinab 10 mg, 25 mg, or 50 mg three times daily (TID) or placebo TID for 12 weeks. The primary endpoint was the change in patient-reported average abdominal pain score (AAPS) from baseline to Week 12.

KEY RESULTS

A total of 273 participants were randomized to receive olorinab 10 mg (n = 67), olorinab 25 mg (n = 67), olorinab 50 mg (n = 69), or placebo (n = 70). Although a treatment response was observed across all groups, the weekly change in average AAPS from baseline to Week 12 was not significantly different between placebo and any olorinab dose. In a prespecified subgroup analysis of participants with a baseline AAPS ≥6.5, olorinab 50 mg (n = 35) significantly improved AAPS compared with placebo (n = 30) (p = 0.014). Adverse event rates were comparable between olorinab and placebo and there were no reported serious adverse events or deaths.

CONCLUSION AND INFERENCES

Although olorinab was well-tolerated and improved weekly AAPS, the primary endpoint was not met. However, in participants with moderate-to-severe pain at baseline (AAPS ≥6.5), olorinab 50 mg significantly improved weekly AAPS compared with placebo.

CLINICALTRIALS

gov: NCT04043455.

Randomised clinical trial: effects of MD-7246 on irritable bowel syndrome with diarrhoea

BACKGROUND

MD-7246, a delayed-release formulation of linaclotide, is designed to target the ileocaecal junction and caecum with the aim of relieving abdominal pain independently of bowel function.

AIMS

To evaluate the efficacy, safety and dose-response of MD-7246 in patients with irritable bowel syndrome with diarrhoea (IBS-D).

METHODS

A randomised, double-blind, phase 2 clinical trial enrolled adult patients with IBS-D (Rome IV criteria). Patients were randomised to placebo or once-daily oral MD-7246 300, 600 or 1200 μg for 12 weeks. Abdominal and bowel symptoms were assessed daily. Key efficacy endpoints were change from baseline in abdominal pain and responder rates for a 30% reduction in abdominal pain in 6/12 weeks. Additional abdominal pain responder and exploratory bowel function endpoints were also assessed.

RESULTS

Among the 388 randomised patients, there was no significant difference in mean change from baseline in abdominal pain between the MD-7246 300 μg, 600 μg and 1200 μg groups and placebo (-1.93, -1.58, -1.95 and - 2.01, respectively; p > 0.05 for each group vs placebo). The abdominal pain responder rates in the MD-7246 groups were similar to or lower than those in the placebo group. All doses of MD-7246 had a minimal effect on bowel function and were generally well tolerated.

CONCLUSIONS

MD-7246 at the doses studied did not improve abdominal pain relative to placebo in an IBS-D patient population. Similarly, most additional efficacy endpoints showed no improvement with MD-7246 relative to placebo.

Linaclotide Reduced Response Time for Irritable Bowel Syndrome With Constipation Symptoms: Analysis of 4 Randomized Controlled Trials

INTRODUCTION

These post hoc analyses provide clinically relevant data concerning time to response for individual irritable bowel syndrome with constipation (IBS-C) symptoms after linaclotide use.

METHODS

Time-to-response data were pooled from 4 randomized controlled trials. Response time for abdominal symptoms (pain, discomfort, and bloating) and complete spontaneous bowel movements (CSBMs) were analyzed using the Kaplan-Meier method; patients were categorized as early responders (≤4 weeks), late responders (>4-12 weeks), or nonresponders.

RESULTS

Among 2,350 patients (1,172 placebo and 1,178 linaclotide 290 μg), >50% of patients with IBS-C who initiated linaclotide treatment experienced a decrease of ≥30% in abdominal pain, discomfort, or bloating within 3-4 weeks (median). The median time to achieving ≥3 CSBMs was 4 weeks. Although not all linaclotide-treated patients responded within 12 weeks, a late response occurred between 4 and 12 weeks in 1 in 6 patients for abdominal pain and in approximately 1 in 10 patients for CSBM frequency. Comparisons of early responders, late responders, and nonresponders for both response definitions indicated that women, Whites, and patients with less severe baseline abdominal symptoms were more likely to respond early.

DISCUSSION

Although treatment responses with linaclotide occurred in >50% of patients with IBS-C within 4 weeks of treatment initiation, benefits for individual abdominal symptoms and/or CSBM frequency can still occur between 4 and 12 weeks. A lack of improvement in one symptom does not negate the possibility of response for others, highlighting the importance of discussing all symptoms with patients and not assuming treatment futility at 4 weeks.

Abdominal Bloating in the United States: Results of a Survey of 88,795 Americans Examining Prevalence and Healthcare Seeking

BACKGROUND & AIMS

Although abdominal bloating is a common symptom, comparatively little is known about its prevalence in the community. This study aimed to examine the prevalence of bloating and assess related health care seeking using survey data from a nationally representative sample of nearly 89,000 Americans.

METHODS

Participants completed the National Gastrointestinal (GI) Survey II to measure the presence and severity of GI symptoms including bloating. We assessed the prevalence of bloating in the past 7 days, as well as severity and health care seeking for bloating. Multivariable regression was performed to identify associations between the outcomes and covariates.

RESULTS

Of 88,795 survey completers, 12,324 (13.9%) reported bloating in the past 7 days. Women and those with comorbidities (eg, irritable bowel syndrome, chronic constipation, ulcerative colitis) and concomitant GI symptoms (eg, abdominal pain, excess gas) had higher odds for bloating (all P < .001). These factors were also associated with more severe bloating (all P < .001). Among those who reported recent bloating, 58.5% never sought care for bloating-29% of whom were self-managing symptoms or were uncomfortable discussing symptoms with their providers.

CONCLUSIONS

Bloating is common in the community because nearly 1 in 7 Americans have experienced this symptom in the past week. Women and those with certain comorbidities and concomitant GI symptoms are more likely to experience bloating and have more severe symptoms. Nearly one third of sufferers who have not sought care are managing symptoms on their own or are uncomfortable discussing it with their providers, emphasizing that efforts should be made to proactively inquire about bloating.

Abdominal Pain Severity Is Mainly Associated with Bloating Severity in Patients with Functional Bowel Disorders and Functional Abdominal Pain

PURPOSE

Abdominal pain is a cardinal sign of functional bowel disorders (FBD), in favor of irritable bowel syndrome (IBS). However, the determinants of abdominal pain severity (APS) are unknown. The present study aimed to search the relationships between APS and demographic, psychological, and clinical parameters in tertiary care FBD outpatients.

PATIENTS AND METHODS

In this retrospective study, we included 2043 new outpatients with FBD or functional abdominal pain. They fulfilled the Rome III questionnaire, psychological evaluation, and four 10-points Likert scale for the perceived severity of constipation, diarrhea, bloating, and abdominal pain. Linear regression was performed for each phenotype to model the severity of abdominal pain with demographic, psychological parameters, and symptoms severity.

RESULTS

APS was positively associated with bloating severity in all phenotypes, but APS was also associated with other variables according to gender and phenotype. APS was negatively associated with age and positively with depression, constipation severity, and diarrhea severity in female patients. In male patients, APS was associated with state anxiety, constipation severity, and diarrhea severity. APS severity was associated with bloating severity and transit severity in IBS patients, while in non-IBS patients, APS was only associated with bloating severity.

CONCLUSION

Perceived abdominal pain severity is always associated with perceived bloating severity in FBD and FAP patients.

Saccharomyces cerevisiae I-3856 in irritable bowel syndrome with predominant constipation

BACKGROUND

Probiotics are a promising solution for managing irritable bowel syndrome (IBS). Saccharomyces cerevisiae (S. cerevisiae) I-3856 has already demonstrated beneficial effects in IBS subjects, particularly in IBS with predominant constipation (IBS-C).

AIM

To confirm the efficacy of S. cerevisiae I-3856 in the management of gastrointestinal symptoms in IBS-C.

METHODS

A randomized, double-blind, placebo-controlled clinical study was performed in a total of 456 subjects. After a run-in period, subjects were randomly assigned to the group receiving S. cerevisiae I-3856 (8 × 10⁹ CFU daily) or the placebo for 8 wk, and they performed daily self-evaluations of gastrointestinal symptoms. The primary objective was to assess the effect of the probiotic on abdominal pain. The secondary objectives were the evaluation of other gastrointestinal symptoms, bowel movement frequency and consistency, and quality of life (QOL).

RESULTS

A significantly higher proportion of abdominal pain responders was reported in the Probiotic group (45.1% vs 33.9%, P = 0.017). A nonsignificant difference in the area under the curve for abdominal pain over the second month of supplementation was observed in subjects receiving probiotic vs placebo [P = 0.073, 95%CI: -0.59 (-1.23; 0.05)]. No statistically significant differences were reported in the evolution of bowel movement frequency and stool consistency between the groups. After 8 wk of supplementation, the overall QOL score was significantly higher in the Probiotic group than in the Placebo group [P = 0.047, 95%CI: 3.86 (0.52; 7.20)]. Furthermore, exploratory analyses showed statistically significant and clinically relevant improvements in QOL scores in abdominal pain responders vs nonresponders.

CONCLUSION

The results of this clinical study confirmed the abdominal pain alleviation properties of S. cerevisiae I-3856 in IBS-C. Abdominal pain relief was associated with improved QOL. ClinicalTrials.gov identifier: NCT03150212.

Mechanism of dexmedetomidine preconditioning on spinal cord analgesia in rats with functional chronic visceral pain

Purpose:

To analyze the effect and mechanism of dexmedetomidine (DEX) analgesia pretreatment on functional chronic visceral pain in rats.

Methods:

Rats were divided into six groups: W1, W2, W3, W4, W5, and W6. The behavioral changes and electrophysiological indexes of rats in each group before and after DEX treatment were detected.

Results:

The levels of abdominal withdrawal reflex (AWR) in W5 and W6 groups were significantly lower than those in group W3, while the levels of thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) were significantly higher than those in group W3 (p < 0.05). The electromyographic signals of W1, W5, and W6 groups showed little fluctuation, while those of groups W2, W3, and W4 showed obvious fluctuation. TLR4 mRNA expression, IRF3, P65, and phosphorylation levels in W4, W5, and W6 groups were significantly lower than those in group W2 (p < 0.05).

Conclusions:

Dexmedetomidine epidural anesthesia pretreatment could significantly inhibit visceral pain response in rats with functional chronic visceral pain, and its mechanism was related to the activation of TLR4 in spinal dorsal horn tissue of rats and the activation inhibition of IRF3 and P65 in the downstream key signals.

Placebo Response Rates in Trials of Licensed Drugs for Irritable Bowel Syndrome With Constipation or Diarrhea: Meta-analysis

BACKGROUND & AIMS

There are several licensed drugs for irritable bowel syndrome (IBS) that have proven efficacy in randomized controlled trials (RCTs), but placebo response rates are high. We conducted a systematic review and meta-analysis of licensed drugs to estimate magnitude of placebo response rate according to Food and Drug Administration (FDA)-recommended endpoints and to assess how this varies with stringency of the endpoint used to define response.

METHODS

We searched MEDLINE, EMBASE CLASSIC and EMBASE, and the Cochrane central register of controlled trials (through January 2021) to identify RCTs comparing licensed drugs with placebo in adult IBS patients. Studies assessed efficacy according to at least one of composite response, abdominal pain response, or stool response. Data were extracted as intention-to-treat analyses, with dropouts assumed to be treatment failures and pooled using a random-effects model.

RESULTS

There were 17 RCTs of licensed drugs versus placebo in IBS with constipation (4603 patients placebo) and 17 trials in IBS with diarrhea (3908 patients placebo). In IBS with constipation, according to FDA criteria, pooled composite, abdominal pain, and stool response rates with placebo over ≥6 of 12 weeks were 18.9%, 34.6%, and 30.1%, respectively. Evaluating response rates over ≥9 of 12 weeks led to placebo response rates of 4.3% for the composite endpoint, 24.5% for abdominal pain, and 7.7% for stool. In IBS with diarrhea, pooled placebo response rates according to FDA criteria were 16.2% for the composite endpoint, 40.2% for abdominal pain, and 16.2% for stool. Increasing the threshold used to define abdominal pain response from ≥30% improvement to ≥40% or ≥50% led to lower placebo response rates of 34.5% and 23.4%.

CONCLUSIONS

Future RCTs should adhere to current FDA-recommended endpoints for IBS because these lead to lower placebo response rates. However, consideration should be given to further refining some of these to better differentiate between active drug and placebo.

Whole Body Pain Distribution and Risk Factors for Widespread Pain Among Patients Presenting with Abdominal Pain: A Retrospective Cohort Study

Introduction

Abdominal pain frequently co-occurs with pain in other body sites. Chronic overlapping pain conditions (COPCs) represent a group of widespread pain diagnoses. Our study characterized how patterns of somatic pain distribution are associated with COPCs and aimed to characterize predictors of widespread pain among patients with chronic abdominal pain.

Methods

This retrospective cohort study included adults presenting to a tertiary pain clinic, reporting abdominal pain at their initial visit, and with a follow-up visit at 12 months. Body maps divided patients into localized, intermediate, and widespread pain distribution patterns. Diagnostic and psychosocial measures were assessed across groups at the initial and follow-up visits. We analyzed the association of baseline diagnoses and demographics and time-varying changes in psychosocial measures from initial to follow-up visit with changes in pain distribution over time with alternating logistic regression (ALR).

Results

Among 258 patients, most were female (91.5%) and reported widespread pain (61.5%). Those with widespread pain at baseline reported elevated anger and 60.0% of patients remained in the same pain category at follow-up. Multivariable ALR demonstrated higher pain interference (AOR 1.06, 95% CI 1.02–1.10, P = 0.002), higher anxiety (AOR 1.05, 95% CI 1.01–1.09, P = 0.01), more than one COPC at initial visit (AOR 2.85, 95% CI 1.59–5.11, P = 0.0005), and initial visit widespread pain categorization (AOR 4.18, 95% CI 2.20–8.00, P < 0.0001) were associated with an increased risk of widespread pain at the follow-up visit.

Conclusion

Most patients with abdominal pain report additional pain locations at multiple other body sites, and non-localized pain persists 12 months after pain treatment. Screening for widespread pain and COPC at the initial visit may identify patients at higher risk for persistent or new-onset widespread pain, and interventions to reduce pain interference and anxiety may promote reversal of widespread pain.

Baseline Predictors of Discontinuation of Prescription Drug Therapy for IBS-C: Cohort Analysis at an Integrated Healthcare System

BACKGROUND

Effective prescription drug treatment of constipation-predominant irritable bowel syndrome (IBS-C) requires patients to remain on daily therapy, yet predictive factors to optimize treatment selection are unknown.

AIMS

We assessed whether common comorbidities including chronic overlapping pain conditions (COPCs), mood disorders, or concurrent medications influence the risk of discontinuing IBS-C prescription drug therapy.

METHODS

We included all IBS-C patients who initiated treatment with the secretagogues linaclotide or lubiprostone across the Michigan Medicine healthcare system between 2012 and 2016. A Cox proportional hazards model was constructed to model time-to-treatment discontinuation as a valid, quantifiable measure of IBS medication persistence using hazards ratios (HR) with 95% confidence intervals (CI).

RESULTS

Our cohort included 225 patients on linaclotide and 492 on lubiprostone (mean age 48.3 years, 86.9% women, 46.6% with at least one COPC, 60.3% with at least one mood disorder) with an average follow-up of 2.1 years. Patients with at least one COPC (HR = 0.566; 95%CI = 0.371-0.863) and also women (HR = 0.535; 95%CI = 0.307-0.934) had a lower risk of discontinuing linaclotide, while COPCs predicted a trend toward increased discontinuation of lubiprostone (HR = 1.254; 95%CI = 0.997-1.576). Age, comorbid mood disorders, and baseline use of narcotics or benzodiazepines did not significantly mediate the risk of treatment discontinuation; our findings remained stable in univariate and multivariable analyses.

CONCLUSIONS

COPCs and sex appear to influence the likelihood of discontinuation of two commonly prescribed secretagogues, while mood disorders, narcotics, and benzodiazepines may not. Routine assessment for comorbid COPCs prior to initiating therapy may optimize IBS-C treatment selection and outcomes in practice.

Pain in irritable bowel syndrome: Does anything really help?

Pain relief remains a significant challenge in the management of irritable bowel syndrome (IBS): "Does anything really help relieve the pain in patients with IBS?". Interventions aimed at pain relief in patients with IBS include diet, probiotics or antibiotics, antidepressants, antispasmodics, and drugs targeting specific gastrointestinal receptors such as opioid or histamine receptors. In the systematic review and meta-analysis published in this journal, Lambarth et al. examined the literature on the role of oral and parenteral anti-neuropathic agents in the management of pain in patients with IBS. This review article appraises their assessment of the efficacy of the anti-neuropathic agents amitriptyline, pregabalin, gabapentin, and duloxetine in the relief of abdominal pain or discomfort, and impact on overall IBS severity and quality of life. This commentary provides an update of current evidence on the efficacy of the dietary and pharmacological treatments that are available or in development, as well psychological and cognitive behavioral therapy for pain in IBS. Advances in recent years augur well for efficacious treatments that may expand the therapeutic arsenal for pain in IBS.

Review article: current and future treatment approaches for pain in IBS

BACKGROUND

Abdominal pain is a core symptom of IBS and a primary driver of care seeking. Visceral hypersensitivity is a key pathophysiological mechanism and therapeutic target for pain in IBS, with components of peripheral and central sensitisation and psychological factors.

AIM

To review current and future treatment approaches specifically for the pain component of IBS.

METHODS

Pubmed search terms included combinations of irritable bowel, pain, visceral hypersensitivity, novel, new, emerging, future and advances.

RESULTS

Established non-pharmacological treatments for IBS pain include the low FODMAP diet, probiotics and psychological interventions, especially hypnotherapy. Tricyclics remain the best evidenced pharmacological approach with GCC agonists, tenapanor, lubiprostone, eluxadoline and 5HT3 antagonists second line according to patient characteristics and availability. Less well-evidenced current options include anti-spasmodics, peppermint oil, SSRIs, SNRIs, alpha 2 delta ligands, melatonin and histamine antagonists. Patients are vulnerable to iatrogenesis and harmful approaches to be avoided include opioids and unwarranted surgical interventions. For severe pain, the concept of augmentation with combined gut-brain neuromodulators and psychotherapy in a multi-disciplinary setting is considered. A plethora of molecular targets and ligands are emerging from pre-clinical studies, together with early clinical evidence for a range of pharmacological, dietary, neurostimulation and novel psychological treatment delivery methods which are reviewed. The history of such emerging approaches, however, merits both caution and optimism in equal measure.

CONCLUSIONS

Despite good in-roads and emerging options, the management of abdominal pain remains one of the biggest challenges and research priorities for patients with IBS.

Aloe barbadensis Mill. extract improves symptoms in IBS patients with diarrhoea: post hoc analysis of two randomized double-blind controlled studies

BACKGROUND

Aloe barbadensis Mill. (Aloe) extract was found to be well-tolerated, safe and showed beneficial effects in subsets of irritable bowel syndrome (IBS) patients in two randomized, double-blind, controlled studies. However, the individual studies were underpowered to perform subgroup analyses. We therefore determined the effect of Aloe extract in IBS subgroups in a post hoc analysis combining the results from the two studies.

METHODS

Data from the two controlled studies comparing Aloe and control treatment taken orally for 4 weeks, were pooled. Both studies included IBS patients fulfilling the ROME III criteria and IBS Symptom Severity Score (IBS-SSS) was assessed. We analysed the effect of Aloe extract on IBS symptom severity and the proportion of responders (IBS-SSS reduction ⩾ 50) in IBS subgroups.

RESULTS

In total, 213 IBS patients were included in the post hoc subgroup analyses. A reduction in overall symptom severity, primarily driven by effect on pain severity and frequency, comparing baseline versus end of treatment, was recorded in IBS patients with diarrhoea (IBS-D) receiving Aloe (n = 38, p < 0.001) but not control treatment (n = 33, p = 0.33), with difference between the treatment groups (p = 0.01). Moreover, the frequency of responders was higher in IBS-D patients receiving Aloe (n = 22, 58%) compared to control treatment (n = 10, 30%) (p = 0.02). The effect of Aloe extract treatment on IBS symptom severity was not superior to control treatment in the other IBS subtypes.

CONCLUSION

Aloe extract improves symptom severity in IBS-D patients and can be regarded as a safe and effective treatment option for this patient group.

Efficacy of Linaclotide in Reducing Abdominal Symptoms of Bloating, Discomfort, and Pain: A Phase 3B Trial Using a Novel Abdominal Scoring System

INTRODUCTION

Linaclotide improves abdominal pain and constipation in patients with constipation-predominant irritable bowel syndrome (IBS-C). Patients report additional bothersome abdominal symptoms of bloating and discomfort. The intention of this study was to evaluate linaclotide's efficacy in relieving IBS-C-related abdominal symptoms (bloating, discomfort, and pain) using a novel multi-item Abdominal Score (AS).

METHODS

Patients with IBS-C with abdominal pain ≥3 (0-10 scale) were randomized to linaclotide 290 μg or placebo daily for 12 weeks. The AS, derived from the Diary for IBS Symptoms-Constipation, is the average of abdominal bloating, discomfort, and pain at their worst (0 = none, 10 = worst possible). The primary end point was overall change from baseline (CFB) in AS. Secondary end points included CFB in 12-week AS evaluated using cumulative distribution function and 6-week/12-week AS responder (AS improvement ≥2 points for ≥6-week/12-week).

RESULTS

Overall, 614 patients (mean age 46.7 years; 81% female) were randomized. All prespecified end points showed significant benefit of linaclotide vs placebo. The mean overall CFB AS reduction for linaclotide was -1.9 vs -1.2 for placebo (P < 0.0001); the 6-week/12-week AS responder rate was 40.5% for linaclotide vs 23.4% for placebo (odds ratio = 2.2 [95% confidence interval, 1.55-3.12; P < 0.0001]). Diarrhea was the most common treatment-emergent adverse event (linaclotide = 4.6%, placebo = 1.6%).

DISCUSSION

Linaclotide significantly reduced multiple abdominal symptoms important to patients with IBS-C (bloating, discomfort, and pain) compared with placebo, as measured by a novel multi-item AS. The AS, derived from the Diary for IBS Symptoms-Constipation, should be considered for use in future IBS-C clinical studies to measure clinically meaningful improvements beyond traditional end points.

Contrasting Clinician and Insurer Perspectives to Managing Irritable Bowel Syndrome: Multilevel Modeling Analysis

INTRODUCTION

Insurance coverage is an important determinant of treatment choice in irritable bowel syndrome (IBS), often taking precedence over desired mechanisms of action or patient goals/values. We aimed to determine whether routine and algorithmic coverage restrictions are cost-effective from a commercial insurer perspective.

METHODS

A multilevel microsimulation tracking costs and outcomes among 10 million hypothetical moderate-to-severe patients with IBS was developed to model all possible algorithms including common global IBS treatments (neuromodulators; low fermentable oligo-, di-, and mono-saccharides, and polyols; and cognitive behavioral therapy) and prescription drugs treating diarrhea-predominant IBS (IBS-D) or constipation-predominant IBS (IBS-C) over 1 year.

RESULTS

Routinely using global IBS treatments (central neuromodulator; low fermentable oligo-, di-, and mono-saccharides, and polyols; and cognitive behavioral therapy) before US Food and Drug Administration-approved drug therapies resulted in per-patient cost savings of $9,034.59 for IBS-D and $2,972.83 for IBS-C over 1 year to insurers, compared with patients starting with on-label drug therapy. Health outcomes were similar, regardless of treatment sequence. Costs varied less than $200 per year, regardless of the global IBS treatment order. The most cost-saving and cost-effective IBS-D algorithm was rifaximin, then eluxadoline, followed by alosetron. The most cost-saving and cost-effective IBS-C algorithm was linaclotide, followed by either plecanatide or lubiprostone. In no scenario were prescription drugs routinely more cost-effective than global IBS treatments, despite a stronger level of evidence with prescription drugs. These findings were driven by higher prescription drug prices as compared to lower costs with global IBS treatments.

DISCUSSION

From an insurer perspective, routine and algorithmic prescription drug coverage restrictions requiring failure of low-cost behavioral, dietary, and off-label treatments appear cost-effective. Efforts to address insurance coverage and drug pricing are needed so that healthcare providers can optimally care for patients with this common, heterogenous disorder.

Mast cells in the paraventricular nucleus participate in visceral hypersensitivity induced by neonatal maternal separation

Early-life stress (ELS) is a high-risk factor for the development of chronic visceral pain in adulthood. Emerging evidence suggests that mast cells play a key role in the development of visceral hypersensitivity through interaction with neurons. The sensitization of corticotropin-releasing factor (CRF) neurons in the hypothalamic paraventricular nucleus (PVN) plays a pivotal role in the pathogenesis of visceral pain. However, the precise mechanism by which mast cells and CRF neurons interact in the PVN in the pathogenesis of visceral hypersensitivity remains elusive. In the present study, we used neonatal maternal separation (MS), an ELS model, and observed that neonatal MS induced visceral hypersensitivity and triggered PVN mast cell activation in adult rats, which was repressed by intra-PVN infusion of the mast cell stabilizer disodium cromoglycate (cromolyn). Wild-type (WT) mice but not mast cell-deficient KitW-sh/W-sh mice that had experienced neonatal MS exhibited chronic visceral hypersensitivity. MS was associated with an increase in the expression of proinflammatory mediators, the number of CRF+ cells and CRF protein in the PVN, which was prevented by intra-PVN infusion of cromolyn. Furthermore, we demonstrated that intra-PVN infusion of the mast degranulator compound 48/80 significantly induced mast cell activation, resulting in proinflammatory mediator release, CRF neuronal sensitization, and visceral hypersensitivity, which was suppressed by cromolyn. Overall, our findings demonstrated that neonatal MS induces the activation of PVN mast cells, which secrete numerous proinflammatory mediators that may participate in neighboring CRF neuronal activity, ultimately directly inducing visceral hypersensitivity in adulthood.

Impact of Diet on Symptoms of the Irritable Bowel Syndrome

Irritable bowel syndrome (IBS), with its key features of abdominal pain and disturbed bowel habit, is thought by both patients and clinicians to be strongly influenced by diet. However, the complexities of diet have made identifying specific food intolerances difficult. Eating disorders can masquerade as IBS and may need specialist treatment. While typical food allergy is readily distinguished from IBS, the mechanisms of gut-specific adverse reactions to food are only just being defined. These may include gut-specific mast cell activation as well as non-specific activation by stressors and certain foods. Visceral hypersensitivity, in some cases mediated by mast cell activation, plays a key part in making otherwise innocuous gut stimuli painful. Rapidly fermented poorly absorbed carbohydrates produce gaseous distension as well as short-chain fatty acids and lowering of colonic pH which may cause symptoms in IBS patients. Limiting intake of these in low FODMAP and related diets has proven popular and apparently successful in many patients. Existing diet, colonic microbiota and their metabolic products may be helpful in predicting who will respond. Wheat intolerance may reflect the fact that wheat is often a major source of dietary FODMAPs. It may also be either a forme fruste of coeliac disease or non-specific immune activation. Wheat exclusion can be successful in some of these patients. More research is needed to fully understand the mechanisms of food intolerances and how to best ameliorate them in a personalised medicine approach to diet in IBS.

ACG Clinical Guideline: Management of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a highly prevalent, chronic disorder that significantly reduces patients' quality of life. Advances in diagnostic testing and in therapeutic options for patients with IBS led to the development of this first-ever American College of Gastroenterology clinical guideline for the management of IBS using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Twenty-five clinically important questions were assessed after a comprehensive literature search; 9 questions focused on diagnostic testing; 16 questions focused on therapeutic options. Consensus was obtained using a modified Delphi approach, and based on GRADE methodology, we endorse the following: We suggest that a positive diagnostic strategy as compared to a diagnostic strategy of exclusion be used to improve time to initiating appropriate therapy. We suggest that serologic testing be performed to rule out celiac disease in patients with IBS and diarrhea symptoms. We suggest that fecal calprotectin be checked in patients with suspected IBS and diarrhea symptoms to rule out inflammatory bowel disease. We recommend a limited trial of a low fermentable oligosaccharides, disacchardies, monosaccharides, polyols (FODMAP) diet in patients with IBS to improve global symptoms. We recommend the use of chloride channel activators and guanylate cyclase activators to treat global IBS with constipation symptoms. We recommend the use of rifaximin to treat global IBS with diarrhea symptoms. We suggest that gut-directed psychotherapy be used to treat global IBS symptoms. Additional statements and information regarding diagnostic strategies, specific drugs, doses, and duration of therapy can be found in the guideline.