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1.  Clinical Utility of Serologic Testing for Celiac Disease in Ontario 
Executive Summary
Objective of Analysis
The objective of this evidence-based evaluation is to assess the accuracy of serologic tests in the diagnosis of celiac disease in subjects with symptoms consistent with this disease. Furthermore the impact of these tests in the diagnostic pathway of the disease and decision making was also evaluated.
Celiac Disease
Celiac disease is an autoimmune disease that develops in genetically predisposed individuals. The immunological response is triggered by ingestion of gluten, a protein that is present in wheat, rye, and barley. The treatment consists of strict lifelong adherence to a gluten-free diet (GFD).
Patients with celiac disease may present with a myriad of symptoms such as diarrhea, abdominal pain, weight loss, iron deficiency anemia, dermatitis herpetiformis, among others.
Serologic Testing in the Diagnosis Celiac Disease
There are a number of serologic tests used in the diagnosis of celiac disease.
Anti-gliadin antibody (AGA)
Anti-endomysial antibody (EMA)
Anti-tissue transglutaminase antibody (tTG)
Anti-deamidated gliadin peptides antibodies (DGP)
Serologic tests are automated with the exception of the EMA test, which is more time-consuming and operator-dependent than the other tests. For each serologic test, both immunoglobulin A (IgA) or G (IgG) can be measured, however, IgA measurement is the standard antibody measured in celiac disease.
Diagnosis of Celiac Disease
According to celiac disease guidelines, the diagnosis of celiac disease is established by small bowel biopsy. Serologic tests are used to initially detect and to support the diagnosis of celiac disease. A small bowel biopsy is indicated in individuals with a positive serologic test. In some cases an endoscopy and small bowel biopsy may be required even with a negative serologic test. The diagnosis of celiac disease must be performed on a gluten-containing diet since the small intestine abnormalities and the serologic antibody levels may resolve or improve on a GFD.
Since IgA measurement is the standard for the serologic celiac disease tests, false negatives may occur in IgA-deficient individuals.
Incidence and Prevalence of Celiac Disease
The incidence and prevalence of celiac disease in the general population and in subjects with symptoms consistent with or at higher risk of celiac disease based on systematic reviews published in 2004 and 2009 are summarized below.
Incidence of Celiac Disease in the General Population
Adults or mixed population: 1 to 17/100,000/year
Children: 2 to 51/100,000/year
In one of the studies, a stratified analysis showed that there was a higher incidence of celiac disease in younger children compared to older children, i.e., 51 cases/100,000/year in 0 to 2 year-olds, 33/100,000/year in 2 to 5 year-olds, and 10/100,000/year in children 5 to 15 years old.
Prevalence of Celiac Disease in the General Population
The prevalence of celiac disease reported in population-based studies identified in the 2004 systematic review varied between 0.14% and 1.87% (median: 0.47%, interquartile range: 0.25%, 0.71%). According to the authors of the review, the prevalence did not vary by age group, i.e., adults and children.
Prevalence of Celiac Disease in High Risk Subjects
Type 1 diabetes (adults and children): 1 to 11%
Autoimmune thyroid disease: 2.9 to 3.3%
First degree relatives of patients with celiac disease: 2 to 20%
Prevalence of Celiac Disease in Subjects with Symptoms Consistent with the Disease
The prevalence of celiac disease in subjects with symptoms consistent with the disease varied widely among studies, i.e., 1.5% to 50% in adult studies, and 1.1% to 17% in pediatric studies. Differences in prevalence may be related to the referral pattern as the authors of a systematic review noted that the prevalence tended to be higher in studies whose population originated from tertiary referral centres compared to general practice.
Research Questions
What is the sensitivity and specificity of serologic tests in the diagnosis celiac disease?
What is the clinical validity of serologic tests in the diagnosis of celiac disease? The clinical validity was defined as the ability of the test to change diagnosis.
What is the clinical utility of serologic tests in the diagnosis of celiac disease? The clinical utility was defined as the impact of the test on decision making.
What is the budget impact of serologic tests in the diagnosis of celiac disease?
What is the cost-effectiveness of serologic tests in the diagnosis of celiac disease?
Methods
Literature Search
A literature search was performed on November 13th, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1st 2003 and November 13th 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist, then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology.
Studies that evaluated diagnostic accuracy, i.e., both sensitivity and specificity of serology tests in the diagnosis of celiac disease.
Study population consisted of untreated patients with symptoms consistent with celiac disease.
Studies in which both serologic celiac disease tests and small bowel biopsy (gold standard) were used in all subjects.
Systematic reviews, meta-analyses, randomized controlled trials, prospective observational studies, and retrospective cohort studies.
At least 20 subjects included in the celiac disease group.
English language.
Human studies.
Studies published from 2000 on.
Clearly defined cut-off value for the serology test. If more than one test was evaluated, only those tests for which a cut-off was provided were included.
Description of small bowel biopsy procedure clearly outlined (location, number of biopsies per patient), unless if specified that celiac disease diagnosis guidelines were followed.
Patients in the treatment group had untreated CD.
Studies on screening of the general asymptomatic population.
Studies that evaluated rapid diagnostic kits for use either at home or in physician’s offices.
Studies that evaluated diagnostic modalities other than serologic tests such as capsule endoscopy, push enteroscopy, or genetic testing.
Cut-off for serologic tests defined based on controls included in the study.
Study population defined based on positive serology or subjects pre-screened by serology tests.
Celiac disease status known before study enrolment.
Sensitivity or specificity estimates based on repeated testing for the same subject.
Non-peer-reviewed literature such as editorials and letters to the editor.
Population
The population consisted of adults and children with untreated, undiagnosed celiac disease with symptoms consistent with the disease.
Serologic Celiac Disease Tests Evaluated
Anti-gliadin antibody (AGA)
Anti-endomysial antibody (EMA)
Anti-tissue transglutaminase antibody (tTG)
Anti-deamidated gliadin peptides antibody (DGP)
Combinations of some of the serologic tests listed above were evaluated in some studies
Both IgA and IgG antibodies were evaluated for the serologic tests listed above.
Outcomes of Interest
Sensitivity
Specificity
Positive and negative likelihood ratios
Diagnostic odds ratio (OR)
Area under the sROC curve (AUC)
Small bowel biopsy was used as the gold standard in order to estimate the sensitivity and specificity of each serologic test.
Statistical Analysis
Pooled estimates of sensitivity, specificity and diagnostic odds ratios (DORs) for the different serologic tests were calculated using a bivariate, binomial generalized linear mixed model. Statistical significance for differences in sensitivity and specificity between serologic tests was defined by P values less than 0.05, where “false discovery rate” adjustments were made for multiple hypothesis testing. The bivariate regression analyses were performed using SAS version 9.2 (SAS Institute Inc.; Cary, NC, USA). Using the bivariate model parameters, summary receiver operating characteristic (sROC) curves were produced using Review Manager 5.0.22 (The Nordiac Cochrane Centre, The Cochrane Collaboration, 2008). The area under the sROC curve (AUC) was estimated by bivariate mixed-efects binary regression modeling framework. Model specification, estimation and prediction are carried out with xtmelogit in Stata release 10 (Statacorp, 2007). Statistical tests for the differences in AUC estimates could not be carried out.
The study results were stratified according to patient or disease characteristics such as age, severity of Marsh grade abnormalities, among others, if reported in the studies. The literature indicates that the diagnostic accuracy of serologic tests for celiac disease may be affected in patients with chronic liver disease, therefore, the studies identified through the systematic literature review that evaluated the diagnostic accuracy of serologic tests for celiac disease in patients with chronic liver disease were summarized. The effect of the GFD in patiens diagnosed with celiac disease was also summarized if reported in the studies eligible for the analysis.
Summary of Findings
Published Systematic Reviews
Five systematic reviews of studies that evaluated the diagnostic accuracy of serologic celiac disease tests were identified through our literature search. Seventeen individual studies identified in adults and children were eligible for this evaluation.
In general, the studies included evaluated the sensitivity and specificity of at least one serologic test in subjects with symptoms consistent with celiac disease. The gold standard used to confirm the celiac disease diagnosis was small bowel biopsy. Serologic tests evaluated included tTG, EMA, AGA, and DGP, using either IgA or IgG antibodies. Indirect immunoflurorescence was used for the EMA serologic tests whereas enzyme-linked immunosorbent assay (ELISA) was used for the other serologic tests.
Common symptoms described in the studies were chronic diarrhea, abdominal pain, bloating, unexplained weight loss, unexplained anemia, and dermatitis herpetiformis.
The main conclusions of the published systematic reviews are summarized below.
IgA tTG and/or IgA EMA have a high accuracy (pooled sensitivity: 90% to 98%, pooled specificity: 95% to 99% depending on the pooled analysis).
Most reviews found that AGA (IgA or IgG) are not as accurate as IgA tTG and/or EMA tests.
A 2009 systematic review concluded that DGP (IgA or IgG) seems to have a similar accuracy compared to tTG, however, since only 2 studies identified evaluated its accuracy, the authors believe that additional data is required to draw firm conclusions.
Two systematic reviews also concluded that combining two serologic celiac disease tests has little contribution to the accuracy of the diagnosis.
MAS Analysis
Sensitivity
The pooled analysis performed by MAS showed that IgA tTG has a sensitivity of 92.1% [95% confidence interval (CI) 88.0, 96.3], compared to 89.2% (83.3, 95.1, p=0.12) for IgA DGP, 85.1% (79.5, 94.4, p=0.07) for IgA EMA, and 74.9% (63.6, 86.2, p=0.0003) for IgA AGA. Among the IgG-based tests, the results suggest that IgG DGP has a sensitivity of 88.4% (95% CI: 82.1, 94.6), 44.7% (30.3, 59.2) for tTG, and 69.1% (56.0, 82.2) for AGA. The difference was significant when IgG DGP was compared to IgG tTG but not IgG AGA. Combining serologic celiac disease tests yielded a slightly higher sensitivity compared to individual IgA-based serologic tests.
IgA deficiency
The prevalence of total or severe IgA deficiency was low in the studies identified varying between 0 and 1.7% as reported in 3 studies in which IgA deficiency was not used as a referral indication for celiac disease serologic testing. The results of IgG-based serologic tests were positive in all patients with IgA deficiency in which celiac disease was confirmed by small bowel biopsy as reported in four studies.
Specificity
The MAS pooled analysis indicates a high specificity across the different serologic tests including the combination strategy, pooled estimates ranged from 90.1% to 98.7% depending on the test.
Likelihood Ratios
According to the likelihood ratio estimates, both IgA tTG and serologic test combinationa were considered very useful tests (positive likelihood ratio above ten and the negative likelihood ratio below 0.1).
Moderately useful tests included IgA EMA, IgA DGP, and IgG DGP (positive likelihood ratio between five and ten and the negative likelihood ratio between 0.1 and 0.2).
Somewhat useful tests: IgA AGA, IgG AGA, generating small but sometimes important changes from pre- to post-test probability (positive LR between 2 and 5 and negative LR between 0.2 and 0.5)
Not Useful: IgG tTG, altering pre- to post-test probability to a small and rarely important degree (positive LR between 1 and 2 and negative LR between 0.5 and 1).
Diagnostic Odds Ratios (DOR)
Among the individual serologic tests, IgA tTG had the highest DOR, 136.5 (95% CI: 51.9, 221.2). The statistical significance of the difference in DORs among tests was not calculated, however, considering the wide confidence intervals obtained, the differences may not be statistically significant.
Area Under the sROC Curve (AUC)
The sROC AUCs obtained ranged between 0.93 and 0.99 for most IgA-based tests with the exception of IgA AGA, with an AUC of 0.89.
Sensitivity and Specificity of Serologic Tests According to Age Groups
Serologic test accuracy did not seem to vary according to age (adults or children).
Sensitivity and Specificity of Serologic Tests According to Marsh Criteria
Four studies observed a trend towards a higher sensitivity of serologic celiac disease tests when Marsh 3c grade abnormalities were found in the small bowel biopsy compared to Marsh 3a or 3b (statistical significance not reported). The sensitivity of serologic tests was much lower when Marsh 1 grade abnormalities were found in small bowel biopsy compared to Marsh 3 grade abnormalities. The statistical significance of these findings were not reported in the studies.
Diagnostic Accuracy of Serologic Celiac Disease Tests in Subjects with Chronic Liver Disease
A total of 14 observational studies that evaluated the specificity of serologic celiac disease tests in subjects with chronic liver disease were identified. All studies evaluated the frequency of false positive results (1-specificity) of IgA tTG, however, IgA tTG test kits using different substrates were used, i.e., human recombinant, human, and guinea-pig substrates. The gold standard, small bowel biopsy, was used to confirm the result of the serologic tests in only 5 studies. The studies do not seem to have been designed or powered to compare the diagnostic accuracy among different serologic celiac disease tests.
The results of the studies identified in the systematic literature review suggest that there is a trend towards a lower frequency of false positive results if the IgA tTG test using human recombinant substrate is used compared to the guinea pig substrate in subjects with chronic liver disease. However, the statistical significance of the difference was not reported in the studies. When IgA tTG with human recombinant substrate was used, the number of false positives seems to be similar to what was estimated in the MAS pooled analysis for IgA-based serologic tests in a general population of patients. These results should be interpreted with caution since most studies did not use the gold standard, small bowel biopsy, to confirm or exclude the diagnosis of celiac disease, and since the studies were not designed to compare the diagnostic accuracy among different serologic tests. The sensitivity of the different serologic tests in patients with chronic liver disease was not evaluated in the studies identified.
Effects of a Gluten-Free Diet (GFD) in Patients Diagnosed with Celiac Disease
Six studies identified evaluated the effects of GFD on clinical, histological, or serologic improvement in patients diagnosed with celiac disease. Improvement was observed in 51% to 95% of the patients included in the studies.
Grading of Evidence
Overall, the quality of the evidence ranged from moderate to very low depending on the serologic celiac disease test. Reasons to downgrade the quality of the evidence included the use of a surrogate endpoint (diagnostic accuracy) since none of the studies evaluated clinical outcomes, inconsistencies among study results, imprecise estimates, and sparse data. The quality of the evidence was considered moderate for IgA tTg and IgA EMA, low for IgA DGP, and serologic test combinations, and very low for IgA AGA.
Clinical Validity and Clinical Utility of Serologic Testing in the Diagnosis of Celiac Disease
The clinical validity of serologic tests in the diagnosis of celiac disease was considered high in subjects with symptoms consistent with this disease due to
High accuracy of some serologic tests.
Serologic tests detect possible celiac disease cases and avoid unnecessary small bowel biopsy if the test result is negative, unless an endoscopy/ small bowel biopsy is necessary due to the clinical presentation.
Serologic tests support the results of small bowel biopsy.
The clinical utility of serologic tests for the diagnosis of celiac disease, as defined by its impact in decision making was also considered high in subjects with symptoms consistent with this disease given the considerations listed above and since celiac disease diagnosis leads to treatment with a gluten-free diet.
Economic Analysis
A decision analysis was constructed to compare costs and outcomes between the tests based on the sensitivity, specificity and prevalence summary estimates from the MAS Evidence-Based Analysis (EBA). A budget impact was then calculated by multiplying the expected costs and volumes in Ontario. The outcome of the analysis was expected costs and false negatives (FN). Costs were reported in 2010 CAD$. All analyses were performed using TreeAge Pro Suite 2009.
Four strategies made up the efficiency frontier; IgG tTG, IgA tTG, EMA and small bowel biopsy. All other strategies were dominated. IgG tTG was the least costly and least effective strategy ($178.95, FN avoided=0). Small bowel biopsy was the most costly and most effective strategy ($396.60, FN avoided =0.1553). The cost per FN avoided were $293, $369, $1,401 for EMA, IgATTG and small bowel biopsy respectively. One-way sensitivity analyses did not change the ranking of strategies.
All testing strategies with small bowel biopsy are cheaper than biopsy alone however they also result in more FNs. The most cost-effective strategy will depend on the decision makers’ willingness to pay. Findings suggest that IgA tTG was the most cost-effective and feasible strategy based on its Incremental Cost-Effectiveness Ratio (ICER) and convenience to conduct the test. The potential impact of IgA tTG test in the province of Ontario would be $10.4M, $11.0M and $11.7M respectively in the following three years based on past volumes and trends in the province and basecase expected costs.
The panel of tests is the commonly used strategy in the province of Ontario therefore the impact to the system would be $13.6M, $14.5M and $15.3M respectively in the next three years based on past volumes and trends in the province and basecase expected costs.
Conclusions
The clinical validity and clinical utility of serologic tests for celiac disease was considered high in subjects with symptoms consistent with this disease as they aid in the diagnosis of celiac disease and some tests present a high accuracy.
The study findings suggest that IgA tTG is the most accurate and the most cost-effective test.
AGA test (IgA) has a lower accuracy compared to other IgA-based tests
Serologic test combinations appear to be more costly with little gain in accuracy. In addition there may be problems with generalizability of the results of the studies included in this review if different test combinations are used in clinical practice.
IgA deficiency seems to be uncommon in patients diagnosed with celiac disease.
The generalizability of study results is contingent on performing both the serologic test and small bowel biopsy in subjects on a gluten-containing diet as was the case in the studies identified, since the avoidance of gluten may affect test results.
PMCID: PMC3377499  PMID: 23074399
2.  The Overlap between Irritable Bowel Syndrome and Non-Celiac Gluten Sensitivity: A Clinical Dilemma 
Nutrients  2015;7(12):10417-10426.
The spectrum of gluten-related disorders has widened in recent times and includes celiac disease, non-celiac gluten sensitivity, and wheat allergy. The complex of symptoms associated with these diseases, such as diarrhea, constipation or abdominal pain may overlap for the gluten related diseases, and furthermore they can be similar to those caused by various other intestinal diseases, such as irritable bowel syndrome (IBS). The mechanisms underlying symptom generation are diverse for all these diseases. Some patients with celiac disease may remain asymptomatic or have only mild gastrointestinal symptoms and thus may qualify for the diagnosis of IBS in the general clinical practice. Similarly, the overlap of symptoms between IBS and non-celiac gluten sensitivity (NCGS) often creates a dilemma for clinicians. While the treatment of NCGS is exclusion of gluten from the diet, some, but not all, of the patients with IBS also improve on a gluten-free diet. Both IBS and NCGS are common in the general population and both can coexist with each other independently without necessarily sharing a common pathophysiological basis. Although the pathogenesis of NCGS is not well understood, it is likely to be heterogeneous with possible contributing factors such as low-grade intestinal inflammation, increased intestinal barrier function and changes in the intestinal microbiota. Innate immunity may also play a pivotal role. One possible inducer of innate immune response has recently been reported to be amylase-trypsin inhibitor, a protein present in wheat endosperm and the source of flour, along with the gluten proteins.
doi:10.3390/nu7125541
PMCID: PMC4690093  PMID: 26690475
celiac disease; wheat allergy; intestine; pathogenesis; gluten-related disorders
3.  Five-year follow-up of 263 cases of functional bowel disorder 
AIM: To determine the mortality associated with functional bowel disorders (FBDs) and their possible relationship with organic bowel disease.
METHODS: Patients who satisfied the Rome III criteria for FBD (retrospective diagnosis) were followed up by telephone interview and/or outpatient review at 5 years after their first attendance. The patients were divided into the following groups: irritable bowel syndrome, functional abdominal bloating, functional constipation, functional diarrhea and unspecified FBD. The survival of the FBD patients overall and of those with each FBD were compared with data obtained from the Guangzhou population in 2005. The incidences of colonic cancer overall and for each FBD were compared with data from the Chinese population obtained from 56 cancer registries in 19 provinces of the country in 2008.
RESULTS: Two hundred and sixty-three patients were followed-up. Five patients died, which was not significantly different from the expected survival rate. No differences in mortality among the FBDs were found. There were nine cases of organic bowel disease: three colonic cancers and six colonic polyps. The incidence of colonic cancer in FBD patients was higher than that in the general Chinese population (0.23% vs 0.03%, P < 0.05). There were significant differences in the incidence of colonic cancer among the FBDs (0/134, 0/24, 2/29, 1/66, 0/10, respectively, P < 0.05); functional constipation was the most common. The incidence of colonic polyps was similar among the FBDs. The baseline age of patients who died was greater than that of those who survived (66.60 ± 6.84 years vs 45.14 ± 10.34 years, P < 0.05). The baseline age of patients who had colonic cancer or polyps during follow-up was greater than that of those without colonic cancer or polyps (60.33 ± 1.53 years vs 45.38 ± 10.62 years; 54.50 ± 6.47 years vs 45.34 ± 10.68 years, P < 0.05).
CONCLUSION: FBDs do not increase the risk of death. The incidence of colonic cancer in patients with FBDs may be increased, especially in those with functional constipation and in the elderly.
doi:10.3748/wjg.v19.i9.1466
PMCID: PMC3602507  PMID: 23539637
Functional bowel disorders; Follow-up; Mortality; Colonic cancer; Colonic polyps
4.  Lessons from a Rare Familial Dementia: Amyloid and Beyond 
Here we review the similarities between a rare inherited disorder, familial British dementia (FBD), and the most common of all late-life neurological conditions, Alzheimer's diseases (AD). We describe the symptoms, pathology and genetics of FBD, the biology of the BRI2 protein and mouse models of FBD and familial Danish dementia. In particular, we focus on the evolving recognition of the importance of protein oligomers and aberrant processing of the amyloid β-protein precursor (APP) - themes that are common to both FBD and AD. The initial discovery that FBD is phenotypically similar to AD, but associated with the deposition of an amyloid peptide (ABri) distinct from the amyloid β-protein (Aβ) led many to assume that amyloid production alone is sufficient to initiate disease and that ABri is the molecular equivalent of Aβ. Parallel with work on Aβ, studies of ABri producing animal models and in vitro ABri toxicity experiments caused a revision of the amyloid hypothesis and a focus on soluble oligomers of Aβ and ABri. Contemporaneous other studies suggested that loss of the ABri precursor protein (BRI2) may underlie the cognitive deficits in FBD. In this regard it is important to note that BRI2 has been shown to interact with and regulate the processing of APP, and that mutant BRI2 leads to altered cleavage of APP. A synthesis of these results suggests that a “two-hit mechanism” better explains FBD than earlier toxic gain of function and toxic loss of function models. The lessons learned from the study of FBD imply that the molecular pathology of AD is also likely to involve both aberrant aggregation (in AD, Aβ) and altered APP processing. With regard to FBD, we propose that the C-terminal 11 amino acid of FBD-BRI2 interfere with both the normal function of BRI2 and promotes the production of cystine cross-linked toxic ABri oligomers. In this scenario, loss of BRI2 function leads to altered APP processing in as yet underappreciated ways. Given the similarities between FBD and AD it seems likely that study of the structure of ABri oligomers and FBD-induced changes in APP metabolites will further our understanding of AD.
doi:10.13188/2376-922X.1000009
PMCID: PMC4578630  PMID: 26405694
Amyloid Bri; Amyloid β-protein; Amyloid β-protein precursor protein; Amyloid Dan; Alzheimer's disease; Familial british dementia; Familial danish dementia
5.  Dietary Triggers in Irritable Bowel Syndrome: Is There a Role for Gluten? 
A tight link exists between dietary factors and irritable bowel syndrome (IBS), one of the most common functional syndromes, characterized by abdominal pain/discomfort, bloating and alternating bowel habits. Amongst the variety of foods potentially evoking “food sensitivity”, gluten and other wheat proteins including amylase trypsin inhibitors represent the culprits that recently have drawn the attention of the scientific community. Therefore, a newly emerging condition termed non-celiac gluten sensitivity (NCGS) or non-celiac wheat sensitivity (NCWS) is now well established in the clinical practice. Notably, patients with NCGS/NCWS have symptoms that mimic those present in IBS. The mechanisms by which gluten or other wheat proteins trigger symptoms are poorly understood and the lack of specific biomarkers hampers diagnosis of this condition. The present review aimed at providing an update to physicians and scientists regarding the following main topics: the experimental and clinical evidence on the role of gluten/wheat in IBS; how to diagnose patients with functional symptoms attributable to gluten/wheat sensitivity; the importance of double-blind placebo controlled cross-over trials as confirmatory assays of gluten/wheat sensitivity; and finally, dietary measures for gluten/wheat sensitive patients. The analysis of current evidence proposes that gluten/wheat sensitivity can indeed represent a subset of the broad spectrum of patients with a clinical presentation of IBS.
doi:10.5056/jnm16069
PMCID: PMC5056565  PMID: 27426486
Biomarkers; Dietary factors; Functional bowel disorder; Gluten; Wheat
6.  Symptomatic improvement with gluten restriction in irritable bowel syndrome: a prospective, randomized, double blinded placebo controlled trial 
Intestinal Research  2016;14(4):343-350.
Background/Aims
The existence of non-celiac gluten sensitivity has been debated. Indeed, the intestinal and extra-intestinal symptoms of many patients with irritable bowel syndrome (IBS) but without celiac disease or wheat allergy have been shown to improve on a gluten-free diet. Therefore, this study set out to evaluate the effects of gluten on IBS symptoms.
Methods
We performed a double-blind randomized placebo-controlled rechallenge trial in a tertiary care hospital with IBS patients who fulfilled the Rome III criteria. Patients with celiac disease and wheat allergy were appropriately excluded. The participants were administered a gluten-free diet for 4 weeks and were asked to complete a symptom-based questionnaire to assess their overall symptoms, abdominal pain, bloating, wind, and tiredness on the visual analog scale (0-100) at the baseline and every week thereafter. The participants who showed improvement were randomly assigned to one of two groups to receive either a placebo (gluten-free breads) or gluten (whole cereal breads) as a rechallenge for the next 4 weeks.
Results
In line with the protocol analysis, 60 patients completed the study. The overall symptom score on the visual analog scale was significantly different between the two groups (P<0.05). Moreover, the patients in the gluten intervention group scored significantly higher in terms of abdominal pain, bloating, and tiredness (P<0.05), and their symptoms worsened within 1 week of the rechallenge.
Conclusions
A gluten diet may worsen the symptoms of IBS patients. Therefore, some form of gluten sensitivity other than celiac disease exists in some of them, and patients with IBS may benefit from gluten restrictions.
doi:10.5217/ir.2016.14.4.343
PMCID: PMC5083263  PMID: 27799885
Controlled clinical trial; Irritable bowel syndrome; Glutens; Non-celiac gluten sensitivity; Diet, gluten-free
7.  Clinical Utility of Serologic Testing for Celiac Disease in Asymptomatic Patients 
Executive Summary
Objective
The objective of this evidence-based analysis was to evaluate the clinical utility of serologic testing for celiac disease in asymptomatic individuals presenting with one of the non-gastrointestinal conditions evaluated in this report. The clinical utility was based on the effects of a gluten-free diet (GFD) on outcomes specific to each of these conditions. The prevalence of celiac disease in asymptomatic individuals and one of these non-gastrointestinal conditions was also evaluated.
Clinical Need and Target Population
Celiac Disease
Celiac disease is an autoimmune disease characterized by a chronic inflammatory state of the proximal small bowel mucosa accompanied by structural and functional changes.
Technology Under Evaluation
Serologic Tests for Celiac Disease
There are a number of serologic tests for celiac disease available. Serologic tests are automated with the exception of the anti-endomysial antibody test, which is more time-consuming and operator-dependent than the other tests.
Research Questions
What is the prevalence of asymptomatic celiac disease in patients presenting with one of the non-gastrointestinal conditions evaluated?
What is the effect of the gluten-free diet on condition-specific outcomes in patients with asymptomatic celiac disease presenting with one of the non-gastrointestinal conditions evaluated?
What is the clinical utility of serologic testing for celiac disease in asymptomatic patients presenting with one of the non-gastrointestinal conditions evaluated? The clinical utility was defined as the impact of the GFD on disease specific outcomes.
What is the risk of all-cause mortality and lymphoma in individuals with asymptomatic celiac disease?
What is the budget impact of serologic testing for celiac disease in asymptomatic subjects presenting with one of the non-gastrointestinal conditions evaluated?
Research Methods
Study Population
The study population consisted of individuals with newly diagnosed celiac disease without any symptoms consistent with the disease presenting with one of the non-gastrointestinal conditions evaluated. When evaluating the risk of lymphoma and all-cause mortality, the study population consisted of asymptomatic individuals with a positive celiac disease serologic test and/or small bowel biopsy.
Literature Search
Search Strategy
Literature searches were performed for each disease/condition evaluated between December 2010 and March 2011 using OVID MEDLINE, the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA). No restrictions for start date of search were used.
Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with an unknown eligibility were reviewed with a second clinical epidemiologist and then a group of epidemiologists until consensus was established.
Inclusion Criteria
Studies, systematic reviews, and meta-analyses that assessed the effects of a GFD in patients with newly diagnosed asymptomatic celiac disease presenting with one of the non-gastrointestinal conditions evaluated. If symptoms were not reported in the study but subjects were identified through screening for celiac disease the study was included.
Studies, systematic reviews, and meta-analyses that assessed the prevalence of newly diagnosed asymptomatic celiac disease in patients with one of the non-gastrointestinal conditions evaluated. If symptoms were not reported in the study but subjects were identified through screening for celiac disease the study was included.
Studies, systematic reviews, and meta-analyses that evaluated the risk of all-cause mortality or lymphoma in individuals with asymptomatic celiac disease.
Sample size ≥ 10.
Publications in English.
Exclusion Criteria
Studies that retrospectively assessed the prevalence of asymptomatic celiac disease.
Studies that reported the prevalence of one of the non-gastrointestinal conditions evaluated in subjects already diagnosed with celiac disease.
Studies in individuals with one of the non-gastrointestinal conditions evaluated if the condition could be explained by other causes.
Studies in subjects with celiac disease and symptoms consistent with the disease. If the study included individuals with and without symptoms consistent with celiac disease and their results were analysed separately, the results in individuals without symptoms were included in the analysis.
Studies in which individuals did not report any symptoms consistent with celiac disease at study start but that either retrospectively reported the presence of such symptoms after following a GFD, or that previously presented with symptoms consistent with celiac disease.
Study results published in letters to the editor or comments about other studies.
Studies with a sample size ≥ 10, however, in which less than 10 patients were included in the analysis.
Outcomes of Interest
The effects of a GFD on disease-specific outcomes for each condition evaluated in patients with asymptomatic celiac disease was assessed. The prevalence of asymptomatic celiac disease in patients presenting with one of the conditions evaluated was also assessed.
Results of Evidence-Based Analysis
Three eligible observational studies evaluated the effects of GFD on growth parameters in subjects with asymptomatic celiac disease and idiopathic short stature. Four eligible observational studies evaluated the effects of GFD on metabolic control in subjects with asymptomatic celiac disease and type 1 diabetes. Five eligible observational studies evaluated the risk of all-cause mortality and five eligible observational studies evaluated the risk of lymphoma in subjects with asymptomatic celiac disease. No eligible studies on the effects of the GFD for the other conditions evaluated were identified. Twenty-three eligible studies measured the prevalence of asymptomatic celiac disease in subjects presenting with one of the conditions evaluated.
Prevalence of Celiac Disease in Asymptomatic Patients
The prevalence of celiac disease in asymptomatic patients presenting with one of the conditions evaluated was analysed. Most studies also included a control group that generally consisted of individuals randomly selected from the general population.
Although there was a trend to a higher prevalence of asymptomatic celiac disease in individuals with the conditions evaluated compared to the controls, it only reached statistical significance in type 1 diabetes. No eligible prevalence studies were identified in patients with amenorrhea, delayed puberty, alopecia, and depression.
The Effects of a Gluten-Free Diet on Disease-Specific Outcomes in Patients with Asymptomatic Celiac Disease
The effects of GFD on metabolic control in patients with asymptomatic celiac disease and Type 1 Diabetes
The effects of a GFD on metabolic control (HbA1c, number of hypoglycemic episodes, and changes in insulin dosage) in subjects with asymptomatic celiac disease and type 1 diabetes were evaluated.
One prospective case-control study reported an increase in HbA1c levels in cases with type 1 diabetes and asymptomatic celiac disease after the introduction of a GFD, however, the clinical significance of this change is unclear.
Only one eligible retrospective case-control study evaluated the effects of a GFD on hypoglycemia episodes and since there were inadequate details in the study about both the ascertainment and severity of hypoglycemia episodes in both cases and controls, it is not possible to draw conclusions regarding the effects of a GFD on hypoglycemia episodes based on this study.
One prospective case-control study did not show a statistically significant change in insulin dosage between cases with type 1 diabetes and asymptomatic celiac disease and controls with type 1 diabetes either before or after the introduction of a GFD.
No eligible studies that evaluated the effects of a GFD on the long-term outcomes of type 1 diabetes such as cardiovascular or renal events in patients with asymptomatic celiac disease were identified.
The effects of a Gluten-Free Diet in Patients with Idiopathic Short Stature and Asymptomatic Celiac Disease
A total of 3 eligible studies were identified. All studies consisted of case series that compared growth parameters in subjects with asymptomatic celiac disease and idiopathic short stature before and after the celiac disease was diagnosed and the GFD was instituted.
Most subjects included in the studies demonstrated an improvement in growth parameters. Compliance with the GFD was not reported in the studies. The results of the studies suggest an increase in growth velocity in pediatric patients with asymptomatic celiac disease and idiopathic short stature once a GFD is introduced.
Risk of lymphoma in patients with asymptomatic celiac disease
One retrospective cohort study evaluated the risk of lymphoma in patients with asymptomatic celiac disease. The authors concluded that the number of events identified was low during the long follow-up period and that the risk of overall malignancies was not increased among patients with asymptomatic celiac disease.
Risk of Asymptomatic Celiac Disease in Patients with Lymphoma
Four case-control studies, one of which retrospective, evaluated the risk of asymptomatic celiac disease in patients newly diagnosed with lymphoma. One retrospective cohort study did not show an increase in the risk of lymphoma among subjects with asymptomatic celiac disease. Three prospective case-control studies did not find a statistically significant risk of asymptomatic celiac disease in patients with newly diagnosed lymphoma.
Risk of All-Cause Mortality in Patients with Asymptomatic Celiac Disease
A total of 5 studies that evaluated the risk of all-cause mortality in asymptomatic patients with celiac disease were identified. There were 5 cohort studies, 2 prospective and 3 retrospective. The two prospective studies did not show an increased risk of all-cause mortality in subjects with asymptomatic celiac disease.
Grading of Evidence
The quality of the evidence for each serologic tests evaluated based on the GRADE Working Group criteria. Overall, the quality of the evidence ranged from low to very low depending on the outcome evaluated.
The Clinical Utility of Serologic Testing for Celiac Disease in Asymptomatic Subjects
Eligible studies that evaluated the effects of a GFD on disease-specific outcomes were only identified for two of the conditions evaluated, type 1 diabetes and idiopathic short stature.
The clinical utility of serologic testing for celiac disease in patients with type 1 diabetes without symptoms consistent with celiac disease was not demonstrated since the studies identified did not provide evidence of the impact of the GFD on either metabolic control or long-term outcomes in these patients.
The clinical utility of serologic testing for celiac disease in patients with idiopathic short stature without symptoms consistent with celiac disease was demonstrated since the studies identified showed an acceleration in growth once the diagnosis of celiac disease was made and a GFD was introduced.
The Budget Impact of Serologic Testing for Celiac Disease in Asymptomatic Patients
The budget impact of serologic testing for celiac disease in asymptomatic patients was calculated for the conditions for which clinical utility for serologic testing was demonstrated. The budget impact in patients with idiopathic short stature without symptoms consistent with celiac disease was estimated as C$552,000 as calculated by multiplying the number of individuals in Ontario with idiopathic short stature that may be eligible for the test by the cost of the serologic test for celiac disease.
Conclusions
Based on a review of the literature, there is an increased risk of asymptomatic celiac disease in patients with type 1 diabetes.
Based on low quality evidence, in patients with idiopathic short stature and asymptomatic celiac disease there is an acceleration in growth once a gluten-free diet is introduced.
With the exception of idiopathic short stature, there was no published evidence of clinical utility of celiac disease testing in asymptomatic patients with respect to a gluten-free diet intervention in the other conditions evaluated.
Based on low to very low quality evidence, asymptomatic celiac disease does not confer an increased risk of lymphoma or mortality.
Similarly, in patients with lymphoma there is no increased risk of asymptomatic celiac disease.
PMCID: PMC3377551  PMID: 23074415
8.  Effect of gluten free diet on immune response to gliadin in patients with non-celiac gluten sensitivity 
BMC Gastroenterology  2014;14:26.
Background
Non-celiac gluten sensitivity is a syndrome characterized by gastrointestinal and extra-intestinal symptoms occurring in a few hours/days after gluten and/or other wheat protein ingestion and rapidly improving after exclusion of potential dietary triggers. There are no established laboratory markers for non-celiac gluten sensitivity, although a high prevalence of first generation anti-gliadin antibodies of IgG class has been reported in this condition. This study was designed to characterize the effect of the gluten-free diet on anti-gliadin antibodies of IgG class in patients with non-celiac gluten sensitivity.
Methods
Anti-gliadin antibodies of both IgG and IgA classes were assayed by ELISA in 44 non-celiac gluten sensitivity and 40 celiac disease patients after 6 months of gluten-free diet.
Results
The majority of non-celiac gluten sensitivity patients (93.2%) showed the disappearance of anti-gliadin antibodies of IgG class after 6 months of gluten-free diet; in contrast, 16/40 (40%) of celiac patients displayed the persistence of these antibodies after gluten withdrawal. In non-celiac gluten sensitivity patients anti-gliadin antibodies IgG persistence after gluten withdrawal was significantly correlated with the low compliance to gluten-free diet and a mild clinical response.
Conclusions
Anti-gliadin antibodies of the IgG class disappear in patients with non-celiac gluten sensitivity reflecting a strict compliance to the gluten-free diet and a good clinical response to gluten withdrawal.
doi:10.1186/1471-230X-14-26
PMCID: PMC3926852  PMID: 24524388
Anti gliadin antibodies; Non-celiac gluten sensitivity; Celiac disease
9.  Non-celiac gluten sensitivity: questions still to be answered despite increasing awareness 
Cellular and Molecular Immunology  2013;10(5):383-392.
Recently, the increasing number of patients worldwide who are sensitive to dietary gluten without evidence of celiac disease or wheat allergy has contributed to the identification of a new gluten-related syndrome defined as non-celiac gluten sensitivity. Our knowledge regarding this syndrome is still lacking, and many aspects of this syndrome remain unknown. Its pathogenesis is heterogeneous, with a recognized pivotal role for innate immunity; many other factors also contribute, including low-grade intestinal inflammation, increased intestinal barrier function and changes in the intestinal microbiota. Gluten and other wheat proteins, such as amylase trypsin inhibitors, are the primary triggers of this syndrome, but it has also been hypothesized that a diet rich in fermentable monosaccharides and polyols may elicit its functional gastrointestinal symptoms. The epidemiology of this condition is far from established; its prevalence in the general population is highly variable, ranging from 0.63% to 6%. From a clinical point of view, non-celiac gluten sensitivity is characterized by a wide array of gastrointestinal and extraintestinal symptoms that occur shortly after the ingestion of gluten and improve or disappear when gluten is withdrawn from the diet. These symptoms recur when gluten is reintroduced. Because diagnostic biomarkers have not yet been identified, a double-blind placebo-controlled gluten challenge is currently the diagnostic method with the highest accuracy. Future research is needed to generate more knowledge regarding non-celiac gluten sensitivity, a condition that has global acceptance but has only a few certainties and many unresolved issues.
doi:10.1038/cmi.2013.28
PMCID: PMC4003198  PMID: 23934026
celiac disease; epithelial barrier function; gut inflammation; non-celiac gluten sensitivity; wheat allergy
10.  Small- bowel mucosal changes and antibody responses after low- and moderate-dose gluten challenge in celiac disease 
BMC Gastroenterology  2011;11:129.
Background
Due to the restrictive nature of a gluten-free diet, celiac patients are looking for alternative therapies. While drug-development programs include gluten challenges, knowledge regarding the duration of gluten challenge and gluten dosage is insufficient.
We challenged adult celiac patients with gluten with a view to assessing the amount needed to cause some small-bowel mucosal deterioration.
Methods
Twenty-five celiac disease adults were challenged with low (1-3 g) or moderate (3-5g) doses of gluten daily for 12 weeks. Symptoms, small-bowel morphology, densities of CD3+ intraepithelial lymphocytes (IELs) and celiac serology were determined.
Results
Both moderate and low amounts of gluten induced small-bowel morphological damage in 67% of celiac patients. Moderate gluten doses also triggered mucosal inflammation and more gastrointestinal symptoms leading to premature withdrawals in seven cases. In 22% of those who developed significant small- intestinal damage, symptoms remained absent. Celiac antibodies seroconverted in 43% of the patients.
Conclusions
Low amounts of gluten can also cause significant mucosal deterioration in the majority of the patients. As there are always some celiac disease patients who will not respond within these conditions, sample sizes must be sufficiently large to attain to statistical power in analysis.
doi:10.1186/1471-230X-11-129
PMCID: PMC3240817  PMID: 22115041
11.  Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders 
Nutrients  2013;5(10):3839-3853.
Non Celiac Gluten sensitivity (NCGS) was originally described in the 1980s and recently a “re-discovered” disorder characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected with either celiac disease (CD) or wheat allergy (WA). Although NCGS frequency is still unclear, epidemiological data have been generated that can help establishing the magnitude of the problem. Clinical studies further defined the identity of NCGS and its implications in human disease. An overlap between the irritable bowel syndrome (IBS) and NCGS has been detected, requiring even more stringent diagnostic criteria. Several studies suggested a relationship between NCGS and neuropsychiatric disorders, particularly autism and schizophrenia. The first case reports of NCGS in children have been described. Lack of biomarkers is still a major limitation of clinical studies, making it difficult to differentiate NCGS from other gluten related disorders. Recent studies raised the possibility that, beside gluten, wheat amylase-trypsin inhibitors and low-fermentable, poorly-absorbed, short-chain carbohydrates can contribute to symptoms (at least those related to IBS) experienced by NCGS patients. In this paper we report the major advances and current trends on NCGS.
doi:10.3390/nu5103839
PMCID: PMC3820047  PMID: 24077239
gluten sensitivity; celiac disease; wheat allergy; gluten-related disorders; gluten-free diet
12.  In Celiac Disease, a Subset of Autoantibodies against Transglutaminase Binds Toll-Like Receptor 4 and Induces Activation of Monocytes 
PLoS Medicine  2006;3(9):e358.
Background
Celiac disease is a small intestine inflammatory disorder with multiple organ involvement, sustained by an inappropriate immune response to dietary gluten. Anti-transglutaminase antibodies are a typical serological marker in patients with active disease, and may disappear during a gluten-free diet treatment. Involvement of infectious agents and innate immunity has been suggested but never proven. Molecular mimicry is one of the mechanisms that links infection and autoimmunity.
Methods and Findings
In our attempt to clarify the pathogenesis of celiac disease, we screened a random peptide library with pooled sera of patients affected by active disease after a pre-screening with the sera of the same patients on a gluten-free diet. We identified a peptide recognized by serum immunoglobulins of patients with active disease, but not by those of patients on a gluten-free diet. This peptide shares homology with the rotavirus major neutralizing protein VP-7 and with the self-antigens tissue transglutaminase, human heat shock protein 60, desmoglein 1, and Toll-like receptor 4. We show that antibodies against the peptide affinity-purified from the sera of patients with active disease recognize the viral product and self-antigens in ELISA and Western blot. These antibodies were able to induce increased epithelial cell permeability evaluated by transepithelial flux of [3H] mannitol in the T84 human intestinal epithelial cell line. Finally, the purified antibodies induced monocyte activation upon binding Toll-like receptor 4, evaluated both by surface expression of activation markers and by production of pro-inflammatory cytokines.
Conclusions
Our findings show that in active celiac disease, a subset of anti-transglutaminase IgA antibodies recognize the viral protein VP-7, suggesting a possible involvement of rotavirus infection in the pathogenesis of the disease, through a mechanism of molecular mimicry. Moreover, such antibodies recognize self-antigens and are functionally active, able to increase intestinal permeability and induce monocyte activation. We therefore provide evidence for the involvement of innate immunity in the pathogenesis of celiac disease through a previously unknown mechanism of engagement of Toll-like receptor 4.
A subset of anti-transglutaminase IgA antibodies recognize the viral protein VP-7, suggesting a possible involvement of rotavirus infection in the pathogenesis of celiac disease through a mechanism of molecular mimicry.
Editors' Summary
Background.
Celiac disease is an autoimmune, digestive disorder in which the small intestine (the part of the gut that absorbs nutrients from food) is damaged. In autoimmune diseases, the immune system, which normally provides protection against foreign invaders, attacks a person's own tissues. In celiac disease, this attack is triggered by eating food containing gluten, a mixture of proteins found in wheat, barley, and rye. To avoid malnutrition, people with celiac disease—about one in 100 people of north European descent—must follow a strict, lifelong gluten-free diet, one that avoids baked products, wheat, pasta, and many other foods. If they fail to do this, their immune system may attack not only their gut but also their brain, skin, joints, and other tissues, in part through the production of antibodies (autoantibodies) that recognize a protein (self-antigen) called tissue transglutaminase. Celiac disease is diagnosed also by looking for these autoantibodies in patients' blood when they are on a gluten-containing diet; they rapidly disappear when a gluten-free diet is adopted.
Why Was This Study Done?
A gluten-free diet keeps celiac disease in check but does not cure it and is very difficult to follow. Even the minute amounts of gluten found in medicines, for example, can trigger the production of autoantibodies and active disease. But developing a cure is impossible without a better understanding of how celiac disease develops. Why, for example, do celiac disease patients make anti-transglutaminase antibodies? Were they made initially to ward off an infectious agent but unfortunately also recognized transglutaminase? In this study, the researchers asked whether “molecular mimicry”—cross-reactivity between self-molecules and foreign molecules on bacteria or viruses (pathogens)—might initiate celiac disease. They also asked whether innate immunity (the part of the immune system that responds quickly to general features on pathogens) as well as adaptive immunity (the production of antibodies and immune cells that recognize specific features on pathogens) is involved in the development of celiac disease.
What Did the Researchers Do and Find?
The researchers purified antibodies from blood provided by patients with celiac disease when they were eating food containing gluten and when they were on a gluten-free diet. They used these to identify celiac peptide, a synthetic protein fragment that was recognized only by the antibodies made by patients with active disease. By searching a database of pathogen proteins, the researchers discovered that rotavirus protein VP-7 contains a very similar peptide; a search of a database of human proteins indicated that celiac peptide also resembles peptides found in tissue transglutaminase, Toll-like receptor 4 (TLR4; a protein involved in the innate immune response), and several other self-antigens. Patient antibodies purified through their ability to bind to celiac peptide also bound to VP-7 and to these self-antigens, and only patients with active disease made these antibodies. The researchers also investigated whether these anti-celiac peptide antibodies might affect the gut or the innate immune system. The antibodies increased the permeability of a layer of gut cells growing in a laboratory dish by interacting with the self-antigen desmoglein 1. This protein helps to make impermeable seals between the cells that line the gut so that food antigens in the gut cannot seep out into the tissues where the immune system might detect them. In addition, by binding to TLR4, the anti-celiac peptide antibodies activated monocytes—cells that function in both the innate and adaptive immune response.
What Do These Findings Mean?
The finding that some anti-transglutaminase antibodies recognize the viral protein VP-7 could mean that rotavirus infection, which causes gastroenteritis, helps to initiate celiac disease in susceptible individuals through molecular mimicry. Furthermore, the identification of other self-antigens that contain peptides recognized by the antibodies made during active disease starts to explain why damage occurs outside the gut in people with celiac disease. The ability of these antibodies to recognize all these peptides could be coincidental, but the observation that the antibodies have relevant functional effects—the ability to increase intestinal permeability and to activate monocytes—makes this less likely. More research is needed to reveal exactly how infections and the innate immune response affect the development of celiac disease, but every piece of new information brings the possibility of a cure a little closer.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030358.
US National Institute of Diabetes and Digestive and Kidney Diseases, information for patients on celiac disease
MedlinePlus encyclopedia entries on celiac disease and on autoimmunity
Wikipedia pages on celiac disease and on autoimmunity (note that Wikipedia is a free online encyclopedia that anyone can edit)
doi:10.1371/journal.pmed.0030358
PMCID: PMC1569884  PMID: 16984219
13.  Value of Gluten Patch Test in Diagnosis of Celiac Disease 
Iranian Journal of Pediatrics  2011;21(4):491-496.
Objective
Celiac disease is an intestinal disorder identified by mucus inflammation, villous atrophy and crypt hyperplasia. This disorder can be controlled by elimination of gluten from daily diet. Patients with celiac disease are at greater risk of gastrointestinal malignancy and non-Hodgkin lymphoma than are the general population. This study tries to present the value of gluten patch test for diagnosis of celiac disease.
Methods
In this investigation, the study population was divided into case and control groups. The case group consisted of patients with celiac disease. The control group were patients involved in celiac disease but suffering from other gastrointestinal disorders. Both gluten patch and placebo patch were attached to the skin between the scapulas. The results were read twice: 48 hours and 96 hours after the patch was applied. Patients who showed irritation reactions were withdrawn from this study. The results were analysed by SPSS software, Spearman's test, chi square, and Mann–Whitney tests.
Findings
The value obtained from the gluten patch test after 96 hours are as follows: specification at 95%, sensitivity at 8%, positive prediction value at 67%, and negative prediction value at 43%.
Conclusion
It can be concluded that the gluten patch test is not an efficient test for screening of celiac disease, however, it can be useful for diagnosis of celiac disease if employed and studied with clinical symptoms and serologic and biopsy tests. Furthermore, we should doubt our judgment if the result of gluten patch test for the patient with celiac disease is positive.
PMCID: PMC3446132  PMID: 23056837
Celiac Disease; Food Allergy; Gluten Patch Test
14.  Functional Bowel Disorders in Iranian Population using Rome III Criteria 
Background/Aim:
To study the prevalence and risk factors of functional bowel disorders (FBD) in Iranian community using Rome III criteria.
Materials and Methods:
This study was a cross-sectional household survey conducted from May 2006 to December 2007 in Tehran province, Iran, including 18,180 participants who were selected randomly and interviewed face-to-face by a validated questionnaire based on Rome III criteria.
Results:
In all, 1.1% met the Rome III criteria for irritable bowel syndrome (IBS), 2.4% for functional constipation (FC), and 10.9% of the participants had any type of FBD. Among participants with functional dyspepsia, 83.8% had FBD; the majority cases were unspecified functional bowel disorder (U-FBD). Of the subjects fulfilling the IBS criteria, IBS with constipation (52%) was the most frequent subtype. In the multivariate analysis, women had a higher risk of any FBDs than men, except for functional diarrhea (FD). The prevalence of FBD, FC and FD increased and IBS decreased with increasing age. Marital status was only associated with a decrease in the risk of FBD and FD, respectively. IBS subtypes compared with FC and FD. There was no significant difference between FC and IBS with constipation (IBS-C), except for self-reported constipation; while, IBS with diarrhea (IBS-D) had more symptoms than FD.
Conclusion:
This study revealed a low rate of FBDs among the urban population of Tehran province. The ROME III criteria itself, and the problems with interpretation of the data collection tool may have contributed in underestimating the prevalence of FBD. In addition the reliability of recall over 6 months in Rome III criteria is questionable for our population.
doi:10.4103/1319-3767.65183
PMCID: PMC3003223  PMID: 20616409
Functional bowel disorder; IBS; bloating; constipation; diarrhea; Rome III criteria
15.  Prevalence of Anti-deamidated Gliadin Peptide Antibodies in Asian Patients With Irritable Bowel Syndrome 
Background/Aims
Non-celiac gluten sensitivity has been increasingly recognized as a predisposing factor for irritable bowel syndrome (IBS)-like symptoms in Western populations where celiac disease (CD) is relatively common. In Asia where CD is rare, we wish to determine the prevalence of gluten protein associated serology in IBS patients, which has not been formally studied, and its relation to histological and human leukocyte antigen (HLA) markers.
Methods
We reviewed a consecutive cohort of Asian patients with IBS, who had undergone serologic testing for IgA against deamidated gliadin peptide antibodies (IgA DGP) and IgA anti-endomysium antibodies, and who also had duodenal biopsies during clinical workup. In addition, a subset of Chinese patients with positive serology was further tested for HLA-DQ2 and HLA-DQ8.
Results
Of 186 patients, 34 (18%) were positive for IgA DGP; bloating, abdominal pain, belching and diarrhea were the most commonly reported symptoms but diarrhea as the most bothersome symptom was significantly more common in IgA DGP positive patients. Mildly increased intra-epithelial lymphocytes on duodenal biopsy was also more common (29% vs. 9%, P = 0.001). Nine of 21 Chinese patients tested as IgA DGP positive undertook HLA-DQ2/DQ8 testing, with only 2 being positive for HLA-DQ8. All patients with positive IgA DGP reported symptom improvement with gluten withdrawal.
Conclusions
We have described a series of Asian, mainly Chinese, patients with IBS who were tested positive for IgA DGP, and improved on a gluten exclusion diet. We believe this is the first report of non-celiac gluten sensitivity in Asia, a region where CD is uncommon.
doi:10.5056/jnm.2014.20.2.236
PMCID: PMC4015193  PMID: 24840376
Asian; Celiac disease; Gliadin; Gluten sensitive enteropathy; Irritable bowel syndrome
16.  Epidemiology of Celiac Disease in Iran: A Review 
Celiac disease (CD) was traditionally believed to be a chronic enteropathy, almost exclusively affecting people of European origin. Celiac disease is the permanent intolerance to dietary gluten, the major protein component of wheat. The availability of new, simple, very sensitive and specific serological tests has shown that CD is as common in Middle Eastern countries as in Europe, Australia and New Zealand where the major dietary staple is wheat. A high prevalence of CD has been found in Iran, in both the general population and the at-risk groups, i.e. patients with type 1 diabetes or irritable bowel syndrome (IBS).
In developing countries, serological testing in at risk groups is necessary for early identification of celiac patients. Clinical studies show that presentation with non-specific symptoms or a lack of symptoms is as common in the Middle East as in Europe. Wheat is a major component of the Iranian diet and exposure to wheat proteins induces some degree of immune tolerance, leading to milder symptoms that may be mistaken with other GI disorders. The implementation of gluten free diet (GFD) is a major challenge for both patients and clinicians in Iran, especially since commercial gluten-free products are not available in this area.
PMCID: PMC4154929  PMID: 25197526
Celiac disease; Epidemiology; Iran
17.  The relation between celiac disease, nonceliac gluten sensitivity and irritable bowel syndrome 
Nutrition Journal  2015;14:92.
Wheat products make a substantial contribution to the dietary intake of many people worldwide. Despite the many beneficial aspects of consuming wheat products, it is also responsible for several diseases such as celiac disease (CD), wheat allergy, and nonceliac gluten sensitivity (NCGS). CD and irritable bowel syndrome (IBS) patients have similar gastrointestinal symptoms, which can result in CD patients being misdiagnosed as having IBS. Therefore, CD should be excluded in IBS patients. A considerable proportion of CD patients suffer from IBS symptoms despite adherence to a gluten-free diet (GFD). The inflammation caused by gluten intake may not completely subside in some CD patients. It is not clear that gluten triggers the symptoms in NCGS, but there is compelling evidence that carbohydrates (fructans and galactans) in wheat does. It is likely that NCGS patients are a group of self-diagnosed IBS patients who self-treat by adhering to a GFD.
doi:10.1186/s12937-015-0080-6
PMCID: PMC4561431  PMID: 26345589
18.  The Immune System in Irritable Bowel Syndrome 
The potential relevance of systemic and gastrointestinal immune activation in the pathophysiology and symptom generation in the irritable bowel syndrome (IBS) is supported by a number of observations. Infectious gastroenteritis is the strongest risk factor for the development of IBS and increased rates of IBS-like symptoms have been detected in patients with inflammatory bowel disease in remission or in celiac disease patients on a gluten free diet. The number of T cells and mast cells in the small and large intestine of patients with IBS is increased in a large proportion of patients with IBS over healthy controls. Mediators released by immune cells and likely from other non-immune competent cells impact on the function of enteric and sensory afferent nerves as well as on epithelial tight junctions controlling mucosal barrier of recipient animals, isolated human gut tissues or cell culture systems. Antibodies against microbiota antigens (bacterial flagellin), and increased levels of cytokines have been detected systemically in the peripheral blood advocating the existence of abnormal host-microbial interactions and systemic immune responses. Nonetheless, there is wide overlap of data obtained in healthy controls; in addition, the subsets of patients showing immune activation have yet to be clearly identified. Gender, age, geographic differences, genetic predisposition, diet and differences in the intestinal microbiota likely play a role and further research has to be done to clarify their relevance as potential mechanisms in the described immune system dysregulation. Immune activation has stimulated interest for the potential identification of biomarkers useful for clinical and research purposes and the development of novel therapeutic approaches.
doi:10.5056/jnm.2011.17.4.349
PMCID: PMC3228974  PMID: 22148103
Abdominal pain; Immune system; Irritable bowel syndrome; Mast cells
19.  Divergence of gut permeability and mucosal immune gene expression in two gluten-associated conditions: celiac disease and gluten sensitivity 
BMC Medicine  2011;9:23.
Background
Celiac disease (CD) is an autoimmune enteropathy triggered by the ingestion of gluten. Gluten-sensitive individuals (GS) cannot tolerate gluten and may develop gastrointestinal symptoms similar to those in CD, but the overall clinical picture is generally less severe and is not accompanied by the concurrence of tissue transglutaminase autoantibodies or autoimmune comorbidities. By studying and comparing mucosal expression of genes associated with intestinal barrier function, as well as innate and adaptive immunity in CD compared with GS, we sought to better understand the similarities and differences between these two gluten-associated disorders.
Methods
CD, GS and healthy, gluten-tolerant individuals were enrolled in this study. Intestinal permeability was evaluated using a lactulose and mannitol probe, and mucosal biopsy specimens were collected to study the expression of genes involved in barrier function and immunity.
Results
Unlike CD, GS is not associated with increased intestinal permeability. In fact, this was significantly reduced in GS compared with controls (P = 0.0308), paralleled by significantly increased expression of claudin (CLDN) 4 (P = 0.0286). Relative to controls, adaptive immunity markers interleukin (IL)-6 (P = 0.0124) and IL-21 (P = 0.0572) were expressed at higher levels in CD but not in GS, while expression of the innate immunity marker Toll-like receptor (TLR) 2 was increased in GS but not in CD (P = 0.0295). Finally, expression of the T-regulatory cell marker FOXP3 was significantly reduced in GS relative to controls (P = 0.0325) and CD patients (P = 0.0293).
Conclusions
This study shows that the two gluten-associated disorders, CD and GS, are different clinical entities, and it contributes to the characterization of GS as a condition associated with prevalent gluten-induced activation of innate, rather than adaptive, immune responses in the absence of detectable changes in mucosal barrier function.
doi:10.1186/1741-7015-9-23
PMCID: PMC3065425  PMID: 21392369
20.  Functional gastrointestinal disorders in eating disorder patients: Altered distribution and predictors using ROME III compared to ROME II criteria 
World Journal of Gastroenterology : WJG  2014;20(43):16293-16299.
AIM: To compare the prevalence of Functional gastrointestinal disorders (FGIDs) using ROME III and ROME II and to describe predictors of FGIDs among eating disorder (ED) patients.
METHODS: Two similar cohorts of female ED inpatients, aged 17-50 years, with no organic gastrointestinal or systemic disorders, completed either the ROME III (n = 100) or the ROME II (n = 160) questionnaire on admission for ED treatment. The two ROME cohorts were compared on continuous demographic variables (e.g., age, BMI) using Student’s t-tests, and on categorical variables (e.g., ED diagnosis) using χ2-tests. The relationship between ED diagnostic subtypes and FGID categories was explored using χ2-tests. Age, BMI, and psychological and behavioural predictors of the common (prevalence greater than 20%) ROME III FGIDs were tested using logistic regression analyses.
RESULTS: The criteria for at least one FGID were fulfilled by 83% of the ROME III cohort, and 94% of the ROME II cohort. There were no significant differences in age, BMI, lowest ever BMI, ED diagnostic subtypes or ED-related quality of life (QOL) scores between ROME II and ROME III cohorts. The most prevalent FGIDs using ROME III were postprandial distress syndrome (PDS) (45%) and irritable bowel syndrome (IBS) (41%), followed by unspecified functional bowel disorders (U-FBD) (24%), and functional heartburn (FH) (22%). There was a 29% or 46% increase (depending on presence or absence of cyclic vomiting) in functional gastroduodenal disorders because of the introduction of PDS in ROME III compared to ROME II. There was a 35% decrease in functional bowel disorders (FBD) in Rome III (excluding U-FBD) compared to ROME II. The most significant predictor of PDS was starvation (P = 0.008). The predictor of FH (P = 0.021) and U-FBD (P = 0.007) was somatisation, and of IBS laxative use (P = 0.025). Age and BMI were not significant predictors. The addition of the 6-mo duration of symptoms requirement for a diagnosis in ROME III added precision to many FGIDs.
CONCLUSION: ROME III confers higher precision in diagnosing FGIDs but self-induced vomiting should be excluded from the diagnosis of cyclic vomiting. Psychological factors appear to be more influential in ROME II than ROME III.
doi:10.3748/wjg.v20.i43.16293
PMCID: PMC4239520  PMID: 25473186
Anorexia nervosa; Bulimia nervosa; Eating disorders; Gastrointestinal diseases; Irritable bowel syndrome
21.  Diagnosis of gluten related disorders: Celiac disease, wheat allergy and non-celiac gluten sensitivity 
Cereal crops and cereal consumption have had a vital role in Mankind’s history. In the recent years gluten ingestion has been linked with a range of clinical disorders. Gluten-related disorders have gradually emerged as an epidemiologically relevant phenomenon with an estimated global prevalence around 5%. Celiac disease, wheat allergy and non-celiac gluten sensitivity represent different gluten-related disorders. Similar clinical manifestations can be observed in these disorders, yet there are peculiar pathogenetic pathways involved in their development. Celiac disease and wheat allergy have been extensively studied, while non-celiac gluten sensitivity is a relatively novel clinical entity, believed to be closely related to other gastrointestinal functional syndromes. The diagnosis of celiac disease and wheat allergy is based on a combination of findings from the patient’s clinical history and specific tests, including serology and duodenal biopsies in case of celiac disease, or laboratory and functional assays for wheat allergy. On the other hand, non-celiac gluten sensitivity is still mainly a diagnosis of exclusion, in the absence of clear-cut diagnostic criteria. A multimodal pragmatic approach combining findings from the clinical history, symptoms, serological and histological tests is required in order to reach an accurate diagnosis. A thorough knowledge of the differences and overlap in clinical presentation among gluten-related disorders, and between them and other gastrointestinal disorders, will help clinicians in the process of differential diagnosis.
doi:10.3748/wjg.v21.i23.7110
PMCID: PMC4476872  PMID: 26109797
Celiac disease; Gluten sensitivity; Wheat sensitivity; Allergy; Gluten-free diet
22.  Animal Models to Study Gluten Sensitivity1 
Seminars in immunopathology  2012;34(4):497-511.
The initial development and maintenance of tolerance to dietary antigens is a complex process that, when prevented or interrupted, can lead to human disease. Understanding the mechanisms by which tolerance to specific dietary antigens is attained and maintained is crucial to our understanding of the pathogenesis of diseases related to intolerance of specific dietary antigens. Two diseases that are the result of intolerance to a dietary antigen are celiac disease (CD) and dermatitis herpetiformis (DH). Both of these diseases are dependent upon the ingestion of gluten (the protein fraction of wheat, rye, and barley) and manifest in the gastrointestinal tract and skin, respectively. These gluten-sensitive diseases are two examples of how devastating abnormal immune responses to a ubiquitous food can be. The well-recognized risk genotype for both is conferred by either of the HLA class II molecules DQ2 or DQ8. However, only a minority of individuals who carry these molecules will develop either disease. Also of interest is that the age at diagnosis can range from infancy to 70–80 years of age. This would indicate that intolerance to gluten may potentially be the result of two different phenomena. The first would be that, for various reasons, tolerance to gluten never developed in certain individuals, but that for other individuals, prior tolerance to gluten was lost at some point after childhood. Of recent interest is the concept of non-celiac gluten sensitivity, which manifests as chronic digestive or neurologic symptoms due to gluten, but through mechanisms that remain to be elucidated. This review will address how animal models of gluten-sensitive disorders have substantially contributed to a better understanding of how gluten intolerance can arise and cause disease.
doi:10.1007/s00281-012-0315-y
PMCID: PMC3410984  PMID: 22572887
23.  Complementary and alternative medicine use and cost in functional bowel disorders: A six month prospective study in a large HMO 
Background
Functional Bowel Disorders (FBD) are chronic disorders that are difficult to treat and manage. Many patients and doctors are dissatisfied with the level of improvement in symptoms that can be achieved with standard medical care which may lead them to seek alternatives for care. There are currently no data on the types of Complementary and Alternative Medicine (CAM) used for FBDs other than Irritable Bowel Syndrome (IBS), or on the economic costs of CAM treatments. The aim of this study is to determine prevalence, types and costs of CAM in IBS, functional diarrhea, functional constipation, and functional abdominal pain.
Methods
1012 Patients with FBD were recruited through a health care maintenance organization and followed for 6 months. Questionnaires were used to ascertain: Utilization and expenditures on CAM, symptom severity (IBS-SS), quality of life (IBS-QoL), psychological distress (BSI) and perceived treatment effectiveness. Costs for conventional medical care were extracted from administrative claims.
Results
CAM was used by 35% of patients, at a median yearly cost of $200. The most common CAM types were ginger, massage therapy and yoga. CAM use was associated with female gender, higher education, and anxiety. Satisfaction with physician care and perceived effectiveness of prescription medication were not associated with CAM use. Physician referral to a CAM provider was uncommon but the majority of patients receiving this recommendation followed their physician's advice.
Conclusion
CAM is used by one-third of FBD patients. CAM use does not seem to be driven by dissatisfaction with conventional care. Physicians should discuss CAM use and effectiveness with their patients and refer patients if appropriate.
doi:10.1186/1472-6882-8-46
PMCID: PMC2499988  PMID: 18652682
24.  Testing for gluten-related disorders in clinical practice: The role of serology in managing the spectrum of gluten sensitivity 
Immunoglobulin A tissue transglutaminase is the single most efficient serological test for the diagnosis of celiac disease. It is well known that immunoglobulin A tissue transglutaminase levels correlate with the degree of intestinal damage, and that values can fluctuate in patients over time. Serological testing can be used to identify symptomatic individuals that need a confirmatory biopsy, to screen at-risk populations or to monitor diet compliance in patients previously diagnosed with celiac disease. Thus, interpretation of serological testing requires consideration of the full clinical scenario. Antigliadin tests are no longer recommended for the diagnosis of classical celiac disease. However, our understanding of the pathogenesis and spectrum of gluten sensitivity has improved, and gluten-sensitive irritable bowel syndrome patients are increasingly being recognized. Studies are needed to determine the clinical utility of antigliadin serology in the diagnosis of gluten sensitivity.
PMCID: PMC3088693  PMID: 21523259
Antigliadin antibodies; Antitissue transglutaminase; Celiac disease; Diagnosis; Gluten intolerance; Serology
25.  Non-Celiac Gluten Sensitivity Has Narrowed the Spectrum of Irritable Bowel Syndrome: A Double-Blind Randomized Placebo-Controlled Trial 
Nutrients  2015;7(6):4542-4554.
Several studies have shown that a large number of patients who are fulfilling the criteria for irritable bowel syndrome (IBS) are sensitive to gluten. The aim of this study was to evaluate the effect of a gluten-free diet on gastrointestinal symptoms in patients with IBS. In this double-blind randomized, placebo-controlled trial, 148 IBS patients fulfilling the Rome III criteria were enrolled between 2011 and 2013. However, only 72 out of the 148 commenced on a gluten-free diet for up to six weeks and completed the study; clinical symptoms were recorded biweekly using a standard visual analogue scale (VAS). In the second stage after six weeks, patients whose symptoms improved to an acceptable level were randomly divided into two groups; patients either received packages containing powdered gluten (35 cases) or patients received placebo (gluten free powder) (37 cases). Overall, the symptomatic improvement was statistically different in the gluten-containing group compared with placebo group in 9 (25.7%), and 31 (83.8%) patients respectively (p < 0.001). A large number of patients labelled as irritable bowel syndrome are sensitive to gluten. Using the term of IBS can therefore be misleading and may deviate and postpone the application of an effective and well-targeted treatment strategy in gluten sensitive patients.
doi:10.3390/nu7064542
PMCID: PMC4488801  PMID: 26056920
IBS; non-celiac gluten sensitivity; gluten free diet

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