Performance of antibodies against tissue transglutaminase for the diagnosis of celiac disease: meta-analysis

Celiac disease diagnosis: transglutaminase, duodenal biopsy and genetic tests correlations

Introduction

Celiac disease (CD) is an autoimmune enteropathy triggered by gluten ingestion in genetically susceptible individuals. The haplotypes HLA-DQ2 and DQ8, transglutaminase (TGA) antibodies, and biopsy findings are the main tests performed in the evaluation and CD diagnosis. The objective was to establish possible correlations between transglutaminase levels, genetic markers tests, and qualitative intestinal biopsy findings (modified Marsh classification) at the diagnosis.

Methods

A retrospective cohort study. The selection criteria were confirmed CD cases with genetic tests performed. Statistical analysis was done mainly through One-way ANOVA, Kendall's correlation coefficient (T), and linear regression.

Results

The study included 112 patients, with a mean age of 6 ± 4 years. All cases were tested to HLA-DQ2, and it was positive in 93%. HLA-DQ8 was tested in 73% of cases and it was positive in 61%. The percentage of negative genetic markers (DQ2/DQ8) was 4.5% for patients tested to both haplotypes. A comparison of DQ2/DQ8 (positive and negative) with clinical findings and tests performed did not identify any differences for most of the parameters analyzed. Cases of type I diabetes presented significant negative expression for DQ2(-); p = 0.05 and positive expression for DQ8(+); p = 0.023. The TGA antibody levels ranged from 18 to 36,745 U/ml. An inverse correlation was found between age and TGA-L level (p = 0.043). In 23% of the cases, the TGA levels were greater than 1,000 U/ml and presented a moderate positive correlation with the atrophy biopsy profile (T = 0.245). Patients with an atrophic biopsy profile (Marsh III) had a moderate positive correlation with growth failure (T = 0.218) but a negative correlation with constipation (T = -0.277).

Conclusion

In terms of diagnosis tests for CD, transglutaminase levels and age presented an inverse correlation, with the level decreasing as age increased. A moderately positive correlation was found between mean transglutaminase with intestinal atrophy and growth retardation. The genetic test DQ2 was positive for 93% and negative genetic markers (DQ2/DQ8) represented 4.5% of cases studied.

Latitude and Celiac Disease Prevalence: A Meta-Analysis and Meta-Regression

BACKGROUND & AIMS

The latitudinal gradient effect is described for several autoimmune diseases including celiac disease in the United States. However, the association between latitude and global celiac disease prevalence is unknown. We aimed to explore the association between latitude and serology-based celiac disease prevalence through meta-analysis.

METHODS

We searched MEDLINE, Embase, Cochrane, and Scopus databases from their beginning through June 29, 2018, to identify screening studies that targeted a general population sample, used serology-based screening tests, and provided a clear location from which we could assign a latitude. Studies were excluded if sampling was based on symptoms, risk factors, or referral. Study selection and data extraction were performed by independent reviewers. The association measures between latitude and prevalence of serology-based celiac disease were evaluated with random-effects meta-analyses and meta-regression.

RESULTS

Of the identified 4667 unique citations, 128 studies were included, with 155 prevalence estimates representing 40 countries. Celiac disease was more prevalent at the higher latitudes of 51° to 60° (relative risk [RR], 1.62; 95% CI, 1.09-2.38) and 61° to 70° (RR, 2.30; 95% CI, 1.36-3.89) compared with the 41° to 50° reference level. No statistically significant difference was observed at lower latitudes. When latitude was treated as continuous, we found a statistically significant association between CD prevalence and latitude overall in the world (RR, 1.03, 95% CI, 1.01-1.05) and a subregional analysis of Europe (RR, 1.05; 95% CI, 1.02-1.07) and North America (RR, 1.1; 95% CI, 1.0-1.2).

CONCLUSIONS

In this comprehensive review of screening studies, we found that a higher latitude was associated with greater serology-based celiac disease prevalence.

Screening for Celiac Disease in Patients with Irritable Bowel Syndrome Fulfilling Rome III Criteria

Background Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder. Celiac disease (CD), a treatable autoimmune enteropathy, with varied presentations, may simulate clinically symptoms of IBS. The aim of the present study is to screen for CD in patients with IBS diagnosed based on the Rome III criteria.

Patients and Methods A cross-sectional study was conducted at a secondary care gastrointestinal unit in Al-Salam General Hospital in Mosul city, Iraq, from November 2015 to October 2016. All patients fulfilling the Rome III criteria for IBS were screened for CD using antitissue transglutaminase IgA antibodies (anti-tTG). Patients who tested positive were subjected to endoscopic duodenal biopsy to confirm the diagnosis of CD.

Results A total of 100 patients were included in the present study (58 female and 42 male), the mean age of the participants was 40.8 years old (standard deviation [SD] ± 11.57). Ten patients (10/100, 10%) tested positive for anti-tTG antibodies. Five of the seropositive patients (5/10, 50%) showed positive biopsy results according to the Marsh classification, 3 of whom having diarrhea, and 2 with constipation.

Conclusion Positive serology and biopsy results suggestive of CD are common among patients with IBS. Screening patients with IBS for CD is justified.

Diagnostic accuracy of DNA methylation for head and neck cancer varies by sample type and number of markers tested

Abnormal methylation of certain cancer related genes strongly predicts a diagnosis of head and neck cancer (HNC), while the predictive power of methylation of other DNA markers for HNC remains unclear. To systemically assess the diagnostic value of DNA methylation patterns for HNC and the effect of methylation platform techniques and sample types, we performed a PubMed search for studies of the correlation between DNA methylation and HNC completed before July 2016, and extracted the sensitivity and specificity for methylated biomarkers. Across these studies, DNA methylation showed high sensitivity for diagnosing HNC in solid tissue (0.57), and high specificity in saliva (0.89). Area under the curve (AUC) from summary receiver operating characteristic (SROC) curves revealed that DNA methylation had more diagnostic power in solid tissue (AUC = 0.82) than saliva (AUC = 0.80) or blood (AUC = 0.77). Combinations of multiple methylated genes were more sensitive diagnostic markers than single methylated genes. Our results suggest that the diagnostic accuracy of methylated biomarkers for HNC varied by sample type and were most accurate when results from multiple sample types were considered.

Intraepithelial lymphocytes, scores, mimickers and challenges in diagnosing gluten-sensitive enteropathy (celiac disease)

The upper digestive tract is routinely scoped for several causes of malabsorption, and the number of duodenal biopsy specimens has increased notably in the last 10 years. Gluten-sensitive enteropathy (GSE) is an autoimmune disease, which shows an increasing prevalence worldwide and requires a joint clinico-pathological approach. The classical histopathology of GSE with partial or total villous blunting is well recognized, but the classification of GSE is not straightforward. Moreover, several mimickers of GSE with intraepithelial lymphocytosis have been identified in the last 20 years, with drug interactions and medical comorbidities adding to the conundrum. In this review, we report on the normal duodenal mucosa, the clinical presentation and laboratory diagnosis of GSE, the duodenal intraepithelial lymphocytes and immunophenotype of GSE-associated lymphocytes, the GSE mimickers, the differences "across oceans" among guidelines in diagnosing GSE, and the use of a synoptic report for reporting duodenal biopsies in both children and adults in the 21st century.

Evidence-Informed Expert Recommendations for the Management of Celiac Disease in Children

Although the need for effective long-term follow-up for patients with celiac disease (CD) has been recognized by many expert groups, published practice guidelines have not provided a clear approach for the optimal management of these patients. In an attempt to provide a thoughtful and practical approach for managing these patients, a group of experts in pediatric CD performed a critical review of the available literature in 6 categories associated with CD to develop a set of best practices by using evidence-based data and expert opinion. The 6 categories included the following: bone health, hematologic issues, endocrine problems, liver disease, nutritional issues, and testing. Evidence was assessed by using standardized criteria for evaluating the quality of the data, grade of evidence, and strength of conclusions. Over 600 publications were reviewed, and 172 were chosen for inclusion. The thorough review of the results demonstrated that the quality of the data available was often insufficient to provide unequivocal best practices. However, using the available data and the clinical experience of the panel, a practical framework for the management of children with CD was created. These recommendations were developed by our expert panel and do not necessarily reflect the policy of the American Academy of Pediatrics. The potential usefulness of these best practices is underscored by the fact that consensus, measured by the outcome of anonymous voting, was reached by the panel for 24 of the 25 questions. We hope that these best practices may be useful to the pediatric gastroenterology and larger general pediatric communities.

Celiac disease: advances in diagnosis

Celiac disease (CD) is characterized by small intestinal damage, which is mediated by a gluten-driven inflammatory response. Establishing a robust diagnosis is critical for improved quality of life and prevention of co-morbidities, although treatment is associated with a substantial life-long burden of care for patients and families. Unfortunately, CD remains a challenging diagnosis. As awareness of the disease increases, more diagnoses of CD are being made by primary care physicians. In fact, many patients may not present to a gastroenterologist because their symptoms are not clearly linked to a gastrointestinal pathology. Also, many patients are starting a gluten-free diet without prior testing, a circumstance that leads to even more confusion. Lastly, the number of serologic and genetic tests, and the role of endoscopy, can be confusing. The purpose of this review is to examine diagnostic testing strategies, focusing on published guidelines, for the evaluation of patients with suspected CD.

Co-occurrence of type 1 diabetes mellitus and celiac disease

The co-occurrence of celiac disease (CD) and type 1 diabetes (T1DM) has been reported as 5-7 times more prevalent than CD alone. The clinical presentation and natural history of CD in patients with T1DM may vary considerably. Less than 10% of patients with T1DM and CD show gastrointestinal symptoms. Therefore, experts support screening for CD in T1DM patients, though there is no consensus as to the recommended frequency of screening. When stratified by time since CD diagnosis, longer follow-up and coexistence of CD are associated with significant increased risk of diabetic associated morbidity and mortality. Early CD diagnosis and treatment with a gluten-free diet are essential.

Assessing of Celiac Disease and Nonceliac Gluten Sensitivity

The publication of papers on the topic of gluten related disorders has substantially increased over the last few years. This has motivated healthcare professionals to pay attention not only to celiac disease and wheat allergy but also to a condition termed nonceliac gluten sensitivity (NCGS). Until now this condition has been diagnosed clinically on the basis of exclusion criteria and clinical response to gluten withdrawal. In addition, recent research in this field has shown that other food components distinct from gluten are implicated in NCGS cases, thereby changing our general understanding of NCGS diagnosis in either individuals on gluten containing diets or those already following a gluten-free diet with no proper diagnostic work-up of celiac disease. With this in mind, the assessment of NCGS will require extensive knowledge of celiac disease manifestations and the laboratory tests commonly performed during diagnosis of celiac disease.

A point-of-care test for facing the burden of undiagnosed celiac disease in the Mediterranean area: a pragmatic design study

BACKGROUND

We aimed at assessing the factors that can influence results of the dissemination of an already validated, new generation commercial Point-of-Care Test (POCT) for detecting celiac disease (CD), in the Mediterranean area, when used in settings where it was designed to be administered, especially in countries with poor resources.

METHODS

Pragmatic study design. Family pediatricians at their offices in Italy, nurses and pediatricians in Slovenia and Turkey at pediatricians', schools and university primary care centers looked for CD in 3,559 (1-14 yrs), 1,480 (14-23 yrs) and 771 (1-18 yrs) asymptomatic subjects, respectively. A new generation POCT detecting IgA-tissue antitransglutaminase antibodies and IgA deficiency in a finger-tip blood drop was used. Subjects who tested positive and those suspected of having CD were referred to a Celiac Centre to undergo further investigations in order to confirm CD diagnosis. POCT Positive Predictive Value (PPV) at tertiary care (with Negative Predictive Value) and in primary care settings, and POCT and CD rates per thousand in primary care were estimated.

RESULTS

At tertiary care setting, PPV of the POCT and 95% CI were 89.5 (81.3-94.3) and 90 (56-98.5) with Negative Predictive Value 98.5 (94.2-99.6) and 98.7% (92-99.8) in children and adults, respectively. In primary care settings of different countries where POCT was performed by a different number of personnel, PPV ranged from 16 to 33% and the CD and POCT rates per thousand ranged from 4.77 to 1.3 and from 31.18 to 2.59, respectively.

CONCLUSIONS

Interpretation of POCT results by different personnel may influence the performance of POC but dissemination of POCT is an urgent priority to be implemented among people of countries with limited resources, such as rural populations and school children.

Barriers impeding serologic screening for celiac disease in clinically high-prevalence populations

BACKGROUND

Celiac disease is present in ~1% of the general population in the United States and Europe. Despite the availability of inexpensive serologic screening tests, ~85% of individuals with celiac disease remain undiagnosed and there is an average delay in diagnosis of symptomatic individuals with celiac disease that ranges from ~5.8-11 years. This delay is often attributed to the use of a case-based approach for detection rather than general population screening for celiac disease, and deficiencies at the level of health care professionals. This study aimed to assess if patient-centered barriers have a role in impeding serologic screening for celiac disease in individuals from populations that are clinically at an increased risk for celiac disease.

METHODS

119 adults meeting study inclusion criteria for being at a higher risk for celiac disease were recruited from the general population. Participants completed a survey/questionnaire at the William K. Warren Medical Research Center for Celiac Disease that addressed demographic information, celiac disease related symptoms (gastrointestinal and extraintestinal), family history, co-morbid diseases and conditions associated with celiac disease, and patient-centered barriers to screening for celiac disease. All participants underwent serologic screening for celiac disease using the IgA tissue transglutaminase antibody (IgA tTG) and, if positive, testing for IgA anti-endomysial antibody (IgA EMA) as a confirmatory test.

RESULTS

Two barriers to serologic testing were significant across the participant pool. These were participants not knowing they were at risk for celiac disease before learning of the study, and participants not knowing where to get tested for celiac disease. Among participants with incomes less than $25,000/year and those less than the median age, not having a doctor to order the test was a significant barrier, and this strongly correlated with not having health insurance. Symptoms and co-morbid conditions were similar among those whose IgA tTG were negative and those who tested positive.

CONCLUSION

There are significant patient-centered barriers that impede serologic screening and contribute to the delayed detection and diagnosis of celiac disease. These barriers may be lessened by greater education of the public and health care professionals about celiac disease symptoms, risk factors, and serologic testing.

A practical approach to small bowel biopsy interpretation: celiac disease and its mimics

While celiac disease is the most common cause of villous remodeling and intraepithelial lymphocytosis in the proximal small bowel, there are many entities that can mimic its histologic appearance. The purpose of this review is to discuss normal small bowel histology and the differential diagnosis of celiac disease. Approaches to evaluate increased intraepithelial lymphocytes are presented, followed by a detailed discussion of the pathology of celiac disease. Particular emphasis is given to those conditions that cause intraepithelial lymphocytosis in the setting of preserved villous architecture, although other important entities, such as peptic injury, idiopathic inflammatory bowel disease, medication injury, eosinophilic (allergic) gastroenteritis, autoimmune enteropathy, common variable immunodeficiency, and infections are also reviewed.

Is enteroscopy necessary for diagnosis of celiac disease?

Celiac disease (CD) is an autoimmune inflammatory disease of the small intestine as a result of reaction to wheat protein, gluten. Exclusion of dietary gluten is the mainstay of the treatment that necessitates a precise diagnosis of the disease. Serological screening may aid in identifying patients with suspected CD, which should be confirmed by intestinal biopsy. It has been shown that duodenal biopsies are good for detection of the disease in most patients. However, there is a group of patients with positive serology and inconclusive pathology. As a result of the widespread use of serology, many patients with equivocal findings grow quickly. Unfortunately current endoscopic methods can only diagnose villous atrophy, which can be present in the later grades of disease (i.e., Marsh III). To diagnose CD correctly, going deeper in the intestine may be necessary. Enteroscopy can reveal changes in CD in the intestinal mucosa in 10%-17% of cases that have negative histology at initial workup. Invasiveness of the method limits its use. Capsule endoscopy may be a good substitute for enteroscopy. However, both techniques should be reserved for patients with suspected diagnosis of complications. This paper reviews the current literature in terms of the value of enteroscopy for diagnosis of CD.

Gastrointestinal pathology in celiac disease: a case series of 150 consecutive newly diagnosed patients

The main histologic feature of celiac disease is increased intraepithelial lymphocytes (IELs) with or without villous atrophy of the duodenal mucosa. The aim of this study was to document a broad range of additional morphologic changes in intestinal mucosa biopsy specimens from patients with celiac disease. Our cohort comprised 150 patients with positive tissue transglutaminase serologic findings; 7 were at Corazza stage A1, 58 at stage B1, and 85 at stage B2. IEL counts per 100 epithelial cells ranged from 34 to 156 (mean, 88.6); a significant neutrophilic infiltrate was present in 85 cases (56.7%); eosinophil count ranged from 3 to 50 per high-power field (mean, 14.6). Additional findings included morphologic changes in enterocytes in 68.7%, subepithelial collagen thickening in 45.3%, and associated lymphocytic gastritis in 30.4% of patients. We demonstrated that these underrecognized features, which can be misleading, are not uncommon in celiac disease and were positively associated with more advanced stages of the disease (P < .0001).

Association between levels of IgA antibodies to tissue transglutaminase and gliadin-related nonapeptides in dermatitis herpetiformis

Dermatitis herpetiformis (DH) is an autoimmunity-driven inflammatory blistering dermatosis associated with a gluten-dependent enteropathy. Tissue transglutaminase (tTG) and nonapeptides of gliadin (npG) are considered in its pathomechanism/diagnostics. Here, the diagnostic accuracy of anti-tTG/anti-npG IgA ELISAs in Slavic DH patients with active skin rash was assessed through creating receiver operating characteristic (ROC) curves, determining cutoff values, and calculating correlations between levels of anti-tTG/anti-npG IgA in DH, IgA/neutrophil-mediated non-DH patients and healthy persons. Altogether, sera from 80 Slavic individuals were examined. There were negligible differences between cutoff points obtained by the ELISAs manufacturer and those in this study. There were statistically significant correlations between levels of anti-tTG/anti-npG IgA in both DH group and the group of IgA/neutrophil-mediated non-DH dermatoses. There was no such correlation in healthy controls. It seems that IgA autoantibodies to tTG and npG in the IgA/neutrophil-mediated DH are produced in the coordinated way implying their causal relationship.

New screening tests enrich anti-transglutaminase results and support a highly sensitive two-test based strategy for celiac disease diagnosis

BACKGROUND

The identification of specific serological algorithms allowing the diagnosis of celiac disease (CD) is a new challenge for both the clinic and the laboratory. We compared the diagnostic accuracy of three new tests proposed for CD screening with that of the well established IgA tTG, and ascertained whether any combination of these tools might enhance accuracy in diagnosing CD.

METHODS

In sera from 329 CD and 374 control children, the following were assayed: IgA tTG; IgA/IgG, which identify tTG-gliadin complexes (Aeskulisa Celi Check and CeliCheck IgGA); IgA/IgG, which identify deamidated gliadin peptides and tTG (QUANTA Lite(TM) h-tTG/DGP Screen).

RESULTS

When specificity was set at 100%, the most sensitive index of CD was IgA tTG (75.7%, cut-off=100U), followed by QUANTA Lite(TM) h-tTG/DGP Screen (65.3%, cut-off 145U), Aeskulisa Celi Check (62.6%, cut-off 909U/mL) and CeliCheck IgGA (59.6%, cut-off 977U/mL). Three algorithms were obtained by combining IgA tTG with each of the new tests. The algorithm obtained by measuring IgA tTG and QUANTA Lite(TM) h-tTG/DGP Screen allowed the correct identification of CD in 78.7% of cases (negative predictive value=97.3%).

CONCLUSIONS

The two-test based strategy could be used for the cost effective diagnosis of CD.

Celiac disease: an underappreciated issue in women&#x2019;s health

Celiac disease (CD) is an immune-mediated enteropathy that is secondary to gluten ingestion and classically associated with gastrointestinal symptoms. Diagnosis is based on serology and confirmatory duodenal biopsy, and the only treatment is lifelong avoidance of gluten. CD has been increasingly recognized to encompass a wide variety of manifestations that are relevant to women&#x2019;s health, including infertility, adverse pregnancy outcomes and reduced BMD. Currently, CD is underdiagnosed, largely owing to lack of recognition of the diverse manifestations by general practitioners. Increased awareness of the clinical spectrum of this disease, as well as targeted testing in at-risk individuals (including women with unexplained infertility and previous adverse pregnancy outcomes, and in specific populations with reduced BMD) is greatly needed in order to improve rates of diagnosis.

Clinical utility of serologic testing for celiac disease in ontario: an evidence-based analysis

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/yearIn 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 13(th), 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 1(st) 2003 and November 13(th) 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. Inclusion Criteria Inclusion CriteriaExclusion CriteriaStudies 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 studiesBoth IgA and IgG antibodies were evaluated for the serologic tests listed above.

OUTCOMES OF INTEREST

SensitivitySpecificityPositive and negative likelihood ratiosDiagnostic 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. (ABSTRACT TRUNCATED)

Diagnostic immunology in celiac disease

Serum autoantibodies to transglutaminase and endomysium are found in the majority of patients with celiac disease, an autoimmune multisystem disorder affecting approximately 1% of Western and Middle-Eastern populations. Detection of these antibodies plays a crucial role in the diagnosis of celiac disease. The aim of this review is to summarize recent publications in this field, with particular focus on the applications and limitations of celiac autoantibody testing in routine clinical practice.

Suboptimal performance of IgG anti-tissue transglutaminase in the diagnosis of celiac disease in a tropical country

Serological tests using human IgA-anti-tTG have been reported to have high sensitivity and specificity in diagnosis of celiac disease. There is a paucity of data on the use of human IgG-anti-tTG in diagnosis of celiac disease. Ninety-two patients with clinical suspicion of celiac disease who underwent duodenal mucosal biopsy and celiac serology using human IgG-anti-tTG were included in this retrospective study. Diagnostic accuracy of human recombinant IgG-anti-tTG serological test for celiac disease was evaluated. Indications for celiac serological testing were diarrhea (92.3%), hypoalbuminemia (39.1%), and anemia (35.9%). Eighteen patients were diagnosed with having celiac disease and 14 (77.8%) of them were IgG-anti-tTG positive. Of the remaining 74 patients, eight (10.8%) were false-positive for IgG-anti-tTG. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of IgG-anti-tTG in celiac disease were 77.8, 89.1, 63.6, 94.2, and 87%, respectively. Human IgG-anti-tTG alone does not perform well as a diagnostic tool for celiac disease. The utility of anti-endomysial antibodies in a similar clinical setting needs to be evaluated.

Autoantibody screen in inflammatory myopathies high prevalence of antibodies to gliadin

BACKGROUND

Inflammatory myopathies (IM) are associated with autoimmune diseases.

AIM

To evaluate the titers of auto-antibodies specific to various autoimmune diseases in patients with IM compared with controls.

METHODS

Sera from 99 IM patients and 100 healthy controls were tested for autoantibodies for vasculitis (myeloperoxidase, PR3, and glomerular basement membrane) and autoimmune gastrointestinal diseases (IgA and IgG antigliadin, antitissue transglutaminase, and Saccharomyces cerevisiae) utilizing the BioPlex 2200 Multiplexed Immunoassay method (Biorad).

RESULTS

Antigliadin IgA levels were significantly elevated in IM patients compared with controls (0.37 units +/- 0.44 vs. 0.24 units +/- 0.15, P = 0.017). Antitissue transglutaminase IgA was marginally increased in IM patients versus controls (0.36 units +/- 1.12 vs. 0.2 units +/- 0.0, P = 0.08).

CONCLUSIONS

Antibodies to gliadin and tissue transglutaminase characteristic for celiac disease were elevated in patients with IM compared with controls. This may indicate a higher prevalence of gluten sensitivity or celiac disease in IM.

Use of likelihood ratios improves clinical interpretation of IgA anti-tTG antibody testing for celiac disease

BACKGROUND

We investigated whether taking into account IgA anti-tissue transglutaminase antibody concentration (IgA anti-tTG) and total IgA concentration could improve clinical interpretation of serologic testing for celiac disease (CD).

METHODS

We retrospectively identified 43 consecutive newly diagnosed CD patients and 545 consecutive disease control patients who had an IgA anti-tTG request during the 42-month study period and for whom intestinal biopsy results were available.

RESULTS

Sensitivity and specificity of the IgA anti-tTG assay from Genesis was 95.3% and 92.7%, respectively, with a likelihood ratio (LR) of 12.4. The LR for CD markedly increased with increasing IgA anti-tTG concentration (from 2.0 for results between 7 and 20 U/ml up to 319 for results >100 U/ml). The LR for CD was also higher in patients with a normal IgA concentration (0.82-4.53 g/L) compared to patients with an increased IgA concentration (15.3 vs. 3.1, respectively). These observations were confirmed with a second IgA anti-tTG assay from BioRad.

CONCLUSION

Sensitivity of IgA anti-tTG was good. Specificity, however, was reduced when IgA anti-tTG was weak positive or when the IgA concentration was increased. Taking into account IgA anti-tTG concentration and IgA concentration improves clinical interpretation of serologic testing for CD.

Clinical presentation of celiac disease and the diagnostic accuracy of serologic markers in children

There has been growing recognition of a changing clinical presentation of celiac disease (CD), with the manifestation of milder symptoms. Serologic testing is widely used to screen patients with suspected CD and populations at risk. The aim of this retrospective analysis was to evaluate the clinical presentation of CD in childhood, assess the diagnostic value of serologic tests, and investigate the impact of IgA deficiency on diagnostic accuracy. We evaluated 206 consecutive children with suspected CD on the basis of clinical symptoms and positive serology results. Ninety-four (46%) had biopsy-proven CD. The median age at diagnosis of CD was 6.8 years; 15% of the children were <2 years of age. There was a higher incidence of CD in girls (p = 0.003). Iron deficiency and intestinal complaints were more frequent in children with CD than those without CD (61% vs. 33%, p = 0.0001 and 71% vs. 55%, p = 0.02, respectively), while failure to thrive was less common (35% vs. 53%, p = 0.02). The sensitivity of IgA tissue transglutaminase (IgA-tTG) was 0.98 when including all children and 1.00 after excluding children with selective IgA deficiency. The specificity of IgA-tTG was 0.73 using the recommended cut-off value of 20 IU, and this improved to 0.94 when using a higher cut-off value of 100 IU. All children with CD and relative IgA deficiency (IgA levels that are measurable but below the age reference [n = 8]) had elevated IgA-tTG. In conclusion, CD is frequently diagnosed in school-age children with relatively mild symptoms. The absence of intestinal symptoms does not preclude the diagnosis of CD; many children with CD do not report intestinal symptoms. While the sensitivity of IgA-tTG is excellent, its specificity is insufficient for the diagnostic confirmation of a disease requiring life-long dietary restrictions. Children with negative IgA-tTG and decreased but measurable IgA values are unlikely to have CD.

Pre-endoscopic screening for Helicobacter pylori and celiac disease in young anemic women

AIM

To evaluate the usefulness of pre-endoscopic serological screening for Helicobacter pylori (H pylori) infection and celiac disease in women aged < 50 years affected by iron-deficiency anemia (IDA).

METHODS

One hundred and fifteen women aged < 50 years with IDA were tested by human recombinant tissue transglutaminase IgA antibodies (tTG) and anti-H pylori IgG antibodies. tTG and H pylori IgG antibody were assessed using an enzyme-linked immunosorbent assay (ELISA). All women were invited to undergo upper GI endoscopy. During gastroscopy, biopsies were collected from antrum (n = 3), gastric body (n = 3) and duodenum (n = 4) in all patients, irrespective of test results. The assessment of gastritis was performed according to the Sydney system and celiac disease was classified by Marsh's System.

RESULTS

45.2% women were test-positive: 41 patients positive for H pylori antibodies, 9 patients for tTG and 2 patients for both. The gastroscopy compliance rate of test-positive women was significantly increased with respect to those test-negative (65.4% vs 42.8%; Fisher test P = 0.0239). The serological results were confirmed by gastroscopy in 100% of those with positive H pylori antibodies, in 50% of those with positive tTG and in 81.5% of test-negative patient. Sensitivity and specificity were 84.8% and 100%, respectively for H pylori infection and, 80% and 92.8% for tTG. Twenty-eight patients had positive H pylori antibodies and in all the patients, an active H pylori infection was found. In particular, in 23 out of 28 (82%) patients with positive H pylori antibodies, a likely cause of IDA was found because of the active inflammation involving the gastric body.

CONCLUSION

Anti-H pylori IgG antibody and tTG IgA antibody testing is able to select women with IDA to submit for gastroscopy to identify H pylori pangastritis and/or celiac disease, likely causes of IDA.

Antibodies against synthetic deamidated gliadin peptides for celiac disease diagnosis and follow-up in children

BACKGROUND

AGA IgA II and AGA IgG II have recently been suggested as reliable tools for celiac disease (CD) diagnosis. We compared their utility for diagnosis and monitoring CD in children with that of tTG IgA, an established CD marker.

METHODS

We studied a cohort of 161 CD and 129 control children in whom CD was histologically confirmed or ruled out. We followed 37 children with CD on a gluten-free diet for 12-84 months. In fasting sera, we measured AGA IgA II, AGA IgG II, and tTG IgA using ELISAs.

RESULTS

The best sensitivity (92.5%), specificity (97.6%), positive predictive value (98%), and negative predictive value (91.2%) were obtained using tTG IgA. AGA IgG II correctly identified 3 of 3 children with CD with total IgA deficiency who had negative AGA IgA II and tTG IgA results. In children <2 years old without total IgA deficiency, AGA IgG II and tTG IgA performed equally well (sensitivity 96.4% and specificity 100%). AGA IgA II, AGA IgG II, and tTG IgA concentrations diminished significantly (P < 0.0001) after 1 year of a gluten-free diet, reaching values below the cutoff in 87%, 70%, and 51% of cases, respectively.

CONCLUSIONS

The best available index for diagnosing CD in children was tTG IgA. In infants <2 years old, AGA IgG II performed as well as tTG IgA in cases without total IgA deficiency and allowed detection of CD when total IgA was <0.06 g/L. Gluten-free diet monitoring can be achieved using any of the studied serum markers.

How many duodenal biopsy specimens are required to make a diagnosis of celiac disease?

BACKGROUND

It is unknown how many endoscopic biopsy specimens are needed to diagnose celiac disease (CD).

OBJECTIVE

To determine the numbers of duodenal biopsy specimens needed to diagnose CD.

DESIGN

Retrospective medical record audit, histology slide analysis, and chart review.

SETTING

A tertiary-care university hospital.

PATIENTS

Adults who underwent EGD to diagnose CD.

INTERVENTIONS

Our pathology database was searched for the keywords "consistent with celiac disease," "not consistent with celiac disease," "villous atrophy," and "intraepithelial lymphocytes" from January 2001 to May 2006. The number of biopsy specimens was determined and graded for a modified Marsh classification, and charts were reviewed for diagnosis verification. CD was confirmed if Marsh grade 3A was found, even on one biopsy specimen.

MAIN OUTCOME MEASUREMENTS

The number of biopsy specimens needed to make the diagnosis of CD.

RESULTS

Of 247 cases, 102 patients were diagnosed with biopsy specimen-confirmed CD. In 9 patients, CD could not be confirmed on the basis of histology alone (highest Marsh lesion was grade 1 or 2), but a clinical diagnosis was made on the basis of presentation and serology. CD could be confirmed if only 2 biopsy specimens were obtained in 84 patients (90%), if only 3 biopsy specimens were obtained in an additional 5 patients (95%), and if at least 4 biopsy specimens were taken in the remainder. CD was ruled out in 145 patients. In 142 patients, biopsy specimens were uniformly negative; 3 patients had Marsh grade 1 lesions but negative serology.

LIMITATIONS

A retrospective design.

CONCLUSIONS

Only 2 biopsy specimens will lead to a confirmed diagnosis of CD in 90%, and a suspected diagnosis in all. For 100% confidence in diagnosis of CD, 4 duodenal biopsy specimens should be taken.

Strongly positive tissue transglutaminase antibodies are associated with Marsh 3 histopathology in adult and pediatric celiac disease

GOALS

Our objective was to determine whether high serologic IgA tissue transglutaminase antibodies (TTGA) are exclusively associated with celiac disease (CD).

BACKGROUND

IgA TTGA are found in the serum of most individuals with CD. This serologic marker is used to screen individuals with suspected CD for duodenal biopsy, the gold standard of CD diagnosis. Data suggest strongly positive IgA TTGA >or= 100 units are highly specific for CD histopathology in pediatric patients and may be sufficient for diagnosis.

STUDY

Records of adult and pediatric subjects in the celiac study at the University of Utah and University of California Irvine were reviewed for strongly positive TTGA. Pathology reports from duodenal biopsies of subjects with IgA TTGA >or= 100 units were graded as 0 to 3 by modified Marsh criteria.

RESULTS

From a pool of 1882 subjects with IgA TTGA assayed, 208 had IgA TTGA >or= 100 units. Seventy-six of these, including 28 children and 48 adults, also had duodenal biopsies. Villous atrophy (Marsh 3 histopathology) was found on biopsy in 73 (96%) of these subjects. The remaining 3 subjects had intermediate Marsh histology. One (Marsh 1) had a complete serologic response to a gluten-free diet and 2 had Marsh 2 lesions and positive endomysium, making early CD most likely.

CONCLUSIONS

IgA TTGA >or= 100 units occur almost exclusively in the setting of Marsh 3 duodenal histopathology in adults and children. Rare cases without villous atrophy were marked by intermediate Marsh changes suggestive of early CD. IgA TTGA >or= 100 arbitrary units indicate duodenal changes consistent with CD.

Cost-effectiveness analysis of strategies for diagnosing celiac disease

OBJECTIVE

To compare strategies for diagnosing celiac disease (CD).

METHODS

A decision analytic model was used to compare five strategies on diagnostic performance and costs.

RESULTS

First, tTG screening alone is the least costly strategy ($22/individual). While the NPV is high (99.8%), the PPV is low (63.4%). Second, if tTG-positive patients undergo esophagogastroduodenoscopy (EGD) to confirm CD, the PPV increases to 100% ($2,237/false-positive diagnosis avoided). Third, if EGDs are restricted to only those who are both tTG and HLA DQ2/8 positive, costs are slightly reduced ($59 vs. $63/individual), while PPV and NPV remain unchanged. Fourth, screening tTG-negative patients for IgA deficiency increases the NPV to 99.9% ($32,605/false-negative diagnosis avoided). Sensitivity analyses revealed that as the prevalence of CD increases, the cost of avoiding a false-positive diagnosis by adding EGD to the tTG alone strategy increases considerably.

CONCLUSIONS

When the pre-test probability of CD is low, patients with positive tTG serology should undergo EGD with biopsy-either directly or after positive screening for HLA DQ2/8-to confirm CD. As the pre-test probability of CD increases, the added cost of EGD should be weighed against the consequences of a false-positive diagnosis. Routinely screening for IgA deficiency in order to avoid a false-negative diagnosis is quite costly.

Celiac disease screening by immunochromatographic visual assays: results of a multicenter study

OBJECTIVE

To assay the efficiency for celiac disease (CD) screening of 2 immunochromatographic visual stick assays based on human recombinant tissue transglutaminase (tTG). One was the antitissue transglutaminase antibodies (AtTGA) stick for IgA/G antibodies to tTG detection, the other was the AtTGA/antigliadin antibodies (AGA) stick for IgA antibodies for tTG and/or gliadins.

PATIENTS AND METHODS

In a prospective multicenter study, 4 pediatric gastroenterology units from Spain and 2 from Latin America enrolled 72 control children with a normal small bowel mucosa and 113 untreated patients with CD with Marsh type 3 lesions.

RESULTS

Evaluation of results by the gastroenterologists and by 2 independent observers at the coordination center showed a remarkably low interobserver variability. For the AtTGA stick, sensitivity was 96.5% and specificity was 98.6%. The AtTGA/AGA stick displayed a sensitivity of 94.5% and a specificity of 98.6% for AtTGA and a sensitivity of 63.1% and a specificity of 95.2% for AGA. The highest efficiency and positive likelihood ratio was obtained for the AtTGA stick, higher than for IgA AtTGA by enzyme-linked immunosorbent assay. One additional advantage was that previous investigation of total serum IgA levels could be eluded. The IgA AtTGA/AGA stick, with an efficiency of 95.1%, compared with 89.2% when the combined results of the 2 enzyme-linked immunosorbent assays were considered, turned out to be an excellent diagnostic tool for infants with no IgA deficiency.

CONCLUSION

These 2 assays are extremely efficient for CD screening, by combining a high diagnostic accuracy with the simplicity and rapidity of visual methods.

Patient assessment in the diagnosis, prevention, and treatment of osteoporosis

Assessment of the patient with osteoporosis includes history and physical examination, laboratory testing, and imaging studies. Information gathered during this assessment assists clinicians in targeting strategies to prevent fractures. The medical history should contain items such as personal and family history of fractures, lifestyle, intake of substances such as vitamin D, calcium, corticosteroids, and other medications. The physical examination can reveal relevant information such as height loss and risk of falls. Bone mineral density (BMD), most commonly determined by dual-energy x-ray absorptiometry, best predicts fracture risk in patients without previous fracture. BMD testing is most efficient in women over 65 years old but is also helpful for men and women with risk factors. Serial BMD tests can identify individuals losing bone mass, but clinicians should be aware of what constitutes a significant change. Laboratory testing can detect other risk factors and can provide clues to etiology. Selection of laboratory tests should be individualized, as there is no consensus regarding which tests are optimal. Biochemical markers of bone turnover have a potential role in fracture risk assessment and in gauging response to therapy, but are not widely used at present. Clinicians should be aware of problems with vitamin D measurement, including seasonal variation, variability among laboratories, and the desirable therapeutic range. Careful assessment of the osteoporotic patient is essential in developing a comprehensive plan that reduces fracture risk and improves quality of life.

Detection of Celiac disease in primary care: a multicenter case-finding study in North America

BACKGROUND

Celiac disease (CD) is one of the most common lifelong disorders in western countries. However, most cases remain currently undiagnosed in North America, mostly due to poor awareness of CD by primary care physicians.

OBJECTIVES

The aims of this study were (a) to determine whether an active case-finding strategy in primary care could increase the frequency of CD diagnosis and (b) to determine the most common clinical presentations of the condition.

METHODS

This was a multicenter, prospective study involving adult subjects during the years 2002-2004, attending one of the participating practices. All individuals with symptoms or conditions known to be associated with CD were tested for immunoglobulin A anti-transglutaminase (tTG) antibodies, and those with elevated anti-tTG were subsequently tested for IgA antiendomysial antibodies (EMA). All subjects who were positive for EMA were advised to undergo an intestinal biopsy and HLA typing.

RESULTS

The study group included 737 women and 239 men, with a median age of 54.3 yr. A positive anti-tTG test was found in 30 out of 976 investigated subjects (3.07%, 95% CI 1.98-4.16). CD was diagnosed in 22 patients (18 women, 4 men). The most frequent reasons for CD screening in these 22 cases were bloating (12/22), thyroid disease (11/22), irritable bowel syndrome (7/22), unexplained chronic diarrhea (6/22), chronic fatigue (5/22), and constipation (4/22). The prevalence of CD in the serologically screened sample was 2.25% (95% CI 1.32-3.18). The diagnostic rate was low at baseline (0.27 cases per thousand visits, 95% CI 0.13-0.41) and significantly increased to 11.6 per thousand visits (95% CI 6.8-16.4, P < 0.001) following active screening implementation.

CONCLUSIONS

This study demonstrates that an active case-finding strategy in the primary care setting is an effective means to improve the diagnostic rate of CD in North America.

Affinity maturation of immunoglobulin A anti-tissue transglutaminase autoantibodies during development of coeliac disease

Coeliac disease (CD) is an immune-mediated enteropathy triggered by ingestion of wheat gluten and related cereals in genetically predisposed individuals. Circulating immunoglobulin A (IgA) class autoantibodies against tissue transglutaminase (IgA-TGA) are highly specific and sensitive serological markers for CD, which is ultimately confirmed by duodenal biopsy. Although CD is considered a life-long disorder, transient or fluctuating IgA-TGA seropositivity has been observed in asymptomatic individuals on a gluten-containing diet. We set out to explore possible differences in the maturation of IgA-TGA avidity between individuals progressing to CD and subjects remaining healthy despite occasional expression of autoantibodies. We developed a time-resolved fluorometric IgA-TGA assay based on human recombinant tissue transglutaminase (tTG), and further modified the method to also measure urea-dependent avidity of the autoantibodies. We measured the autoantibody titres and avidities of sequential serum samples from 10 children developing CD and 10 children presenting transient or fluctuating autoantibodies. Both the initial titres at seroconversion and peak values of transient/fluctuating IgA-TGA were significantly lower than corresponding autoantibody titres in samples drawn from individuals with progressing CD (P = 0.004 and P = 0.0002, respectively). However, there were no statistically significant differences in the initial or peak avidity index values between the two groups of children. The avidity index values increased during the follow-up period (P = 0.013 for both groups) with no significant difference in the rate of avidity maturation between children with transient/fluctuating IgA-TGA and children developing CD. According to our results, high autoantibody titres have a higher predictive value than avidity maturation of TGA-IgA in screening for CD.

Deamidated Gliadin Peptides as Targets for Celiac Disease‐Specific Antibodies

Celiac disease (CD) is an (auto)immunologically mediated intestinal intolerance against proteins from wheat (gluten) and related cereal proteins. Tissue transglutaminase (tTG) has been identified as the autoantigen in CD. Although ultimate diagnosis is based on histological analysis of small intestinal mucosa obtained via tissue biopsy, assessment of autoantibodies can provide substantial help in the evaluation of CD. Gliadin antibodies are directed against the native disease-provoking cereal proteins. Despite their initial usefulness, these antibodies have lost diagnostic importance due to their poor specificity and sensitivity as CD markers. Recently, it was found, however, that gliadin antibodies from sera of patients with active CD preferentially recognized deamidated gliadin peptides. The use of deamidated gliadin peptides in immunoassays has significantly improved the usefulness of gliadin antibodies in diagnosis of CD to that observed with autoantibody assay methods (endomysium antibodies, antibodies against tTG). The antibody epitopes (B-cell epitopes) reflect substrate specificity of tTG and resemble peptide sequences known to be strongly T-cell stimulatory (T-cell epitopes) in CD. The assay applying deamidated gliadin peptides measures a new species of antibodies, which is different from conventional gliadin antibodies as well as from autoantibodies and will likely provide new information on pathophysiological mechanisms of CD.