The effect of expectancy versus actual gluten intake on gastrointestinal and extra-intestinal symptoms in non-coeliac gluten sensitivity: a randomised, double-blind, placebo-controlled, international, multicentre study

BACKGROUND

Many individuals without coeliac disease or wheat allergy reduce their gluten intake because they believe that gluten causes their gastrointestinal symptoms. Symptoms could be affected by negative expectancy. Therefore, we aimed to investigate the effects of expectancy versus actual gluten intake on symptoms in people with non-coeliac gluten sensitivity (NCGS).

METHODS

This randomised, double-blind, placebo-controlled, international, multicentre study was done at the University of Leeds (Leeds, UK), Maastricht University (Maastricht, the Netherlands), and Wageningen University and Research (Wageningen, the Netherlands). People aged 18-70 years with self-reported NCGS (ie, gastrointestinal symptoms within 8 h of gluten consumption) without coeliac disease and wheat allergy were recruited. Participants had to follow a gluten-free or gluten-restricted diet for at least 1 week before (and throughout) study participation and had to be asymptomatic or mildly symptomatic (overall gastrointestinal symptom score ≤30 mm on the Visual Analogue Scale [VAS]) while on the diet. Participants were randomly assigned (1:1:1:1; blocks of eight; stratified by site and gender) to one of four groups based on the expectation to consume gluten-containing (E+) or gluten-free (E-) oat bread for breakfast and lunch (two slices each) and actual intake of gluten-containing (G+) or gluten-free (G-) oat bread. Participants, investigators, and those assessing outcomes were masked to the actual gluten assignment, and participants were also masked to the expectancy part of the study. The primary outcome was overall gastrointestinal symptom score on the VAS, which was measured at and corrected for baseline (before breakfast) and hourly for 8 h, with lunch served after 4 h, and analysed per-protocol. Safety analysis included all participants incorporated in the per-protocol analysis. The study is registered at ClinicalTrials.gov, NCT05779358, and has ended.

FINDINGS

Between Oct 19, 2018, and Feb 14, 2022, 165 people were screened and 84 were randomly assigned to E+G+ (n=21), E+G- (n=21), E-G+ (n=20), or E-G- (n=22). One person in the E+G+ group was excluded due to not following test day instructions, leaving 83 participants in the per-protocol analysis. Median age was 27·0 years (IQR 21·0-45·0), 71 (86%) of 83 people were women, and 12 (14%) were men. Mean overall gastrointestinal symptom score was significantly higher for E+G+ (16·6 mm [95% CI 13·1 to 20·0]) than for E-G+ (6·9 mm [3·5 to 10·4]; difference 9·6 mm [95% CI 3·0 to 16·2], p=0·0010) and E-G- (7·4 mm [4·2 to 10·7]; difference 9·1 mm [2·7 to 15·6], p=0·0016), but not for E+G- (11·7 mm [8·3 to 15·1]; difference 4·9 mm [-1·7 to 11·5], p=0·28). There was no difference between E+G- and E-G+ (difference 4·7 mm [-1·8 to 11·3], p=0·33), E+G- and E-G- (difference 4·2 mm [-2·2 to 10·7], p=0·47), and E-G+ and E-G- (difference -0·5 mm [-7·0 to 5·9], p=1·0). Adverse events were reported by two participants in the E+G- group (itching jaw [n=1]; feeling lightheaded and stomach rumbling [n=1]) and one participant in the E-G+ group (vomiting).

INTERPRETATION

The combination of expectancy and actual gluten intake had the largest effect on gastrointestinal symptoms, reflecting a nocebo effect, although an additional effect of gluten cannot be ruled out. Our results necessitate further research into the possible involvement of the gut-brain interaction in NCGS.

FUNDING

Government of the Netherlands Topsector Agri & Food Top Consortium for Knowledge and Innovation, AB Mauri Global Bakery Ingredients, Baking Industry Research Trust, Borgesius-Albert Heijn, CSM Innovation Centre, the International Maize and Wheat Improvement Center (CIMMYT), DSM Food Specialties, Fazer, Healthgrain Forum, the International Association for Cereal Science and Technology, the International Wheat Gluten Association, Lantmännen, Mondelez International, Nederlands Bakkerij Centrum, Nutrition & Santé, Puratos, Rademaker, Sonneveld Group, and Zeelandia HJ Doeleman.

Satisfaction With Life in IBS Is Associated With Psychological Burden Rather than Gastrointestinal Symptom Severity

INTRODUCTION

Irritable bowel syndrome (IBS) has a major impact on emotional, social, and professional life. This study aimed to evaluate general life satisfaction, a subjective measure of well-being, in IBS patients, and to determine which factors are associated with higher life satisfaction.

METHODS

IBS patients (n = 195, mean age 51.4 ± 16.5 years, 73.8% female) recruited from primary and secondary/tertiary care completed questionnaires regarding gastrointestinal symptoms, quality of life, psychological factors, and life satisfaction (Satisfaction With Life Scale, 5 items, range 5-35). A finite mixture model analysis was performed to identify latent classes. Multivariable linear regression was used to identify variables associated with life satisfaction.

RESULTS

Overall, 71.3% of the patients were satisfied about their life (Satisfaction With Life Scale-score ≥21). Three latent subgroups could be identified with significantly higher life satisfaction in the subgroup with higher mental quality of life, fewer anxiety and depressive symptoms, lower gastrointestinal specific anxiety, and lower gastrointestinal symptom severity, compared with the other 2 groups. Multivariable linear regression showed that higher physical quality of life (B0.168, P < 0.001) and higher mental quality of life (B0.199, P < 0.001) were associated with higher life satisfaction. Using multivariable regression, no significant association was found between gastrointestinal symptom severity and life satisfaction.

DISCUSSION

Higher physical and mental quality of life, but not gastrointestinal symptom severity, were independently associated with higher general life satisfaction in IBS. These findings reinforce the clinical need in IBS treatment to focus on the full extent of the disorder and not merely on gastrointestinal symptom improvement. ClinicalTrials.gov Identifier: NCT00775060.

Diet Quality and Dietary Inflammatory Index in Dutch Inflammatory Bowel Disease and Irritable Bowel Syndrome Patients

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) share common culprit foods and potential pathophysiological factors. However, how diet may contribute to disease course and whether this differs between both entities is unclear. We therefore investigated the association of dietary indices with intestinal inflammation and gastrointestinal symptoms in both IBD and IBS patients. Food frequency questionnaires from 238 IBD, 261 IBS and 195 healthy controls (HC) were available to calculate the overall diet quality by the Dutch Healthy Diet-Index 2015 (DHD-2015) and its inflammatory potential by the Adapted Dietary Inflammatory Index (ADII). Intestinal inflammation and symptoms were evaluated by faecal calprotectin and the Gastrointestinal Symptom Rating Scale, respectively. The DHD-2015 was lower in IBD and IBS versus HC (p < 0.001), being associated with calprotectin levels in IBD (b = −4.009, p = 0.006), and with abdominal pain (b = −0.012, p = 0.023) and reflux syndrome (b = −0.016, p = 0.004) in IBS. ADII scores were comparable between groups and were only associated with abdominal pain in IBD (b = 0.194, p = 0.004). In this side-by-side comparison, we found a lower diet quality that was differentially associated with disease characteristics in IBD versus IBS patients. Longitudinal studies are needed to further investigate the role of dietary factors in the development of flares and predominant symptoms.

Examining the optimal cutoff values of HADS, PHQ-9 and GAD-7 as screening instruments for depression and anxiety in irritable bowel syndrome

BACKGROUND

Self-rating scales are frequently used to screen for anxiety and depression in patients with irritable bowel syndrome (IBS). Different cutoff values are recommended in literature, and guidelines have suggested the use of other screening instruments over time. The aim of this study was to assess the correlation between the most commonly used psychological screening instruments for anxiety and depression in IBS and to compare custom cutoff scores for these instruments.

METHODS

Irritable bowel syndrome patients (n = 192) completed several questionnaires including the Hospital Anxiety and Depression Scale (HADS, HADS-A and HADS-D subscale), Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7). Agreement at different cutoff points, for depressive and anxiety disorder, was assessed by use of the Gwet AC1 coefficient.

KEY RESULTS

Hospital Anxiety and Depression Scale (HADS)-D and PHQ-9 scores, and HADS-A and GAD-7 scores showed high correlations (r_s  = 0.735 and r_s  = 0.805, respectively). For depressive disorder, a Gwet AC1 value of 0.829 was found when recommended cutoff points from literature were compared (PHQ-9 cutoff ≥10, HADS-D cutoff ≥8). For anxiety disorder, a Gwet AC1 value of 0.806 was found when recommended cutoff points from literature were compared (GAD-7 cutoff ≥10, HADS-A cutoff ≥8). Even higher agreements were found when higher HADS cutoff values were chosen, with impact on sensitivity and specificity.

CONCLUSIONS & INFERENCES

Custom cutoff values deem the HADS subscales (HADS-D and HADS-A) concordant to PHQ-9 and GAD-7 scores. The choice of a cutoff value has substantial impact on sensitivity/specificity and is dependent on patient population, setting, and the purpose of use.

Reduction in IBS symptom severity is not paralleled by improvement in quality of life in patients with irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a brain-gut disorder, of which the natural course varies between patients and is difficult to predict. This study aimed to evaluate symptom evolution over a 5-year follow-up period and to identify baseline predictors for symptom severity and quality of life (QoL) at follow-up.

METHODS

Maastricht IBS cohort participants completed questionnaires upon inclusion regarding demographics and lifestyle, gastrointestinal (GI) symptoms, anxiety and depression, and QoL. The same questionnaires, in addition to others, were completed after 5 years. Rome criteria were confirmed face-to-face at initial enrollment and through telephonic interviews at follow-up.

KEY RESULTS

At a mean follow-up of 4.7 years, 379 patients were approached of whom 203 (53.7%) responded. Of these, 161 were reached by telephone and analyzed; 49 (30.4%) did not fulfill the Rome III criteria at follow-up and had lower levels of GI symptoms and GI-specific anxiety compared to those remaining Rome III-positive (P < 0.001). However, Rome III-negative patients had comparable levels of QoL and life satisfaction, comorbid anxiety and depression, work absenteeism, and impaired productivity. No baseline predictors were found for being Rome III-positive or Rome III-negative. However, greater age and lower baseline physical QoL predicted lower physical QoL at follow-up (P < 0.005 and P < 0.01, respectively), while lower baseline mental QoL predicted lower mental QoL at follow-up (P = 0.005). Additionally, higher anxiety and depression scores at follow-up were associated with lower QoL and life satisfaction at follow-up (P < 0.001).

CONCLUSIONS AND INFERENCES

Long-term QoL and general well-being might depend on concurrent psychological symptoms, rather than GI symptom improvement.

The Experience Sampling Method-Evaluation of treatment effect of escitalopram in IBS with comorbid panic disorder

BACKGROUND

Confirming treatment response in clinical trials for irritable bowel syndrome (IBS) is challenging, due to the lack of biomarkers and limitations of the currently available symptom assessment tools. The Experience Sampling Method (ESM) might overcome these limitations by collecting digital assessments randomly and repeatedly during daily life. This study evaluated differences in change in abdominal pain between real-time (ie, ESM) and retrospective (ie, Gastrointestinal Symptom Rating Scale [GSRS] and an end-of-day symptom diary) measurements, using data of an RCT on escitalopram vs placebo in patients with IBS and comorbid panic disorder.

METHODS

Twenty-nine IBS patients with comorbid panic disorder were included in a 6-month RCT. The GSRS, diary, and ESM were completed at baseline (t = 0) and after 3 (t = 3) and 6 months (t = 6). Linear mixed models were used.

KEY RESULTS

Experience Sampling Method analyses revealed a significant interaction between escitalopram and time, and ESM abdominal pain scores were 1.4 points lower in the escitalopram group compared to placebo at t = 6 (on a 1-to-7 scale; P = 0.021). When including the interaction with momentary anxiety, the reduction in abdominal pain scores in escitalopram vs placebo was even more pronounced for higher levels of anxiety. Average GSRS- and end-of-day abdominal pain scores were not significantly different between escitalopram and placebo at t = 3 and 6.

CONCLUSIONS & INFERENCES

Real-time ESM has the potential to capture treatment response more sensitively compared to a retrospective end-of-day GI symptom diary and the GSRS, by taking into account day-to-day symptom variability as well as momentary factors that might moderate treatment effect, such as anxiety.

Rome III vs Rome IV criteria for irritable bowel syndrome: A comparison of clinical characteristics in a large cohort study

BACKGROUND

The Rome criteria for irritable bowel syndrome (IBS) have been revised and are expected to apply only to the subset of Rome III IBS subjects with abdominal pain as predominant symptom, occurring at least once a week. The aim of this study was to determine the percentage of Rome III IBS subjects that fulfills Rome IV criteria and to evaluate differences between Rome IV-positive and Rome IV-negative subjects.

METHODS

Four hundred and four Rome III IBS subjects completed a 14-day end-of-day symptom diary, the Gastrointestinal Symptom Rating Scale (GSRS), Hospital Anxiety and Depression Scale, and RAND 36-item Short-Form Health Survey (SF-36). Diary-based surrogate Rome IV criteria were defined as occurrence of abdominal pain at least 1 day each week with a severity of ≥2 (mild; definition 1) or ≥3 (considerable; definition 2).

KEY RESULTS

Using surrogate Rome IV criteria, 353 (87.4%, definition 1) and 249 (61.6%, definition 2) subjects were defined as Rome IV positive. These patients were more often female, younger, and recruited from secondary/tertiary care compared with Rome IV-negative subjects. They also presented with higher abdominal pain scores and gastrointestinal (GI) symptom severity on both end-of-day diary and GSRS, higher psychological symptom scores, and lower quality of life compared with Rome IV-negative subjects.

CONCLUSIONS AND INFERENCES

The Rome IV IBS population likely reflects a subgroup of Rome III IBS patients with more severe GI symptomatology, psychological comorbidities, and lower quality of life. This implies that results from Rome III IBS studies may not be directly comparable to those from Rome IV IBS populations.

Habitual diet and diet quality in Irritable Bowel Syndrome: A case-control study

BACKGROUND

Diet is considered to be a key factor in symptom generation in Irritable Bowel Syndrome (IBS) and patients tend to exclude food products from their diet in pursue of symptom relief, which may impair diet quality.

METHODS

We evaluated habitual dietary intake in IBS patients with regard to nutrients and food products using an extensive food frequency questionnaire. One hundred ninety-four IBS patients were compared to 186 healthy controls using multiple logistic regression analysis. An overall diet quality score was calculated for each participant based on the criteria of the Dutch Healthy Diet (DHD) index.

KEY RESULTS

A lower DHD-score was found for IBS (mean [SD]: 52.9 [9.6]) vs controls (55.1 [9.2], P=.02). The diet of patients was lower in fibers (21 g vs 25 g per day, P=.002) and fructose (14 g vs 16 g, P=.033), while higher in total fat (37% vs 36% of total energy intake, P=.010) and added sugars (46 g vs 44 g, P=.029). Differences in daily intake of food products included lower consumption of apples (40 g vs 69 g, P<.001), pasta (28 vs 37 g, P=.029) and alcoholic beverages (130 g vs 193 g, P=.024) and higher consumption of processed meat (38 g vs 29 g, P<.001). Some of these findings correlated with gastrointestinal symptoms, showing differences between IBS subtypes.

CONCLUSIONS AND INFERENCES

Differences in habitual diet were described, showing lower diet quality in IBS patients compared to controls, with increased consumption of fat and lower intake of fibers and fructose. Our data support the importance of personalized and professional nutritional guidance of IBS patients.

Small intestinal permeability is increased in diarrhoea predominant IBS, while alterations in gastroduodenal permeability in all IBS subtypes are largely attributable to confounders

BACKGROUND

Intestinal permeability has been studied in small groups of IBS patients with contrasting findings.

AIMS

To assess intestinal permeability at different sites of the GI tract in different subtypes of well-characterised IBS patients and healthy controls (HC), and to assess potential confounding factors.

METHODS

IBS patients and HC underwent a multi-sugar test to assess site-specific intestinal permeability. Sucrose excretion and lactulose/rhamnose ratio in 0-5 h urine indicated gastroduodenal and small intestinal permeability, respectively. Sucralose/erythritol ratio in 0-24 h and 5-24 h urine indicated whole gut and colonic permeability, respectively. Linear regression analysis was used to assess the association between IBS groups and intestinal permeability and to adjust for age, sex, BMI, anxiety or depression, smoking, alcohol intake and use of medication.

RESULTS

Ninety-one IBS patients, i.e. 37% IBS-D, 23% IBS-C, 33% IBS-M and 7% IBS-U and 94 HC were enrolled. Urinary sucrose excretion was significantly increased in the total IBS group [μmol, median (Q1;Q3): 5.26 (1.82;11.03) vs. 2.44 (0.91;5.85), P < 0.05], as well as in IBS-C and IBS-D vs. HC. However, differences attenuated when adjusting for confounders. The lactulose/rhamnose ratio was increased in IBS-D vs. HC [0.023 (0.013;0.038) vs. 0.014 (0.008;0.025), P < 0.05], which remained significant after adjustment for confounders. No difference was found in 0-24 and 5-24 h sucralose/erythritol ratio between groups.

CONCLUSIONS

Small intestinal permeability is increased in patients with IBS-D compared to healthy controls, irrespective of confounding factors. Adjustment for confounders is necessary when studying intestinal permeability, especially in a heterogeneous disorder such as IBS.