Antibodies against deamidated gliadin peptides and tissue transglutaminase for diagnosis of pediatric celiac disease

American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease

This guideline presents an update to the 2013 American College of Gastroenterology Guideline on the Diagnosis and Management of Celiac Disease with updated recommendations for the evaluation and management of patients with celiac disease (CD). CD is defined as a permanent immune-mediated response to gluten present in wheat, barley, and rye. CD has a wide spectrum of clinical manifestations that resemble a multisystemic disorder rather than an isolated intestinal disease, and is characterized by small bowel injury and the presence of specific antibodies. Detection of CD-specific antibodies (e.g., tissue transglutaminase) in the serum is very helpful for the initial screening of patients with suspicion of CD. Intestinal biopsy is required in most patients to confirm the diagnosis. A nonbiopsy strategy for the diagnosis of CD in selected children is suggested and discussed in detail. Current treatment for CD requires strict adherence to a gluten-free diet (GFD) and lifelong medical follow-up. Most patients have excellent clinical response to a GFD. Nonresponsive CD is defined by persistent or recurrent symptoms despite being on a GFD. These patients require a systematic workup to rule out specific conditions that may cause persistent or recurrent symptoms, especially unintentional gluten contamination. Refractory CD is a rare cause of nonresponsive CD often associated with poor prognosis.

Defining the optimum strategy for identifying adults and children with coeliac disease: systematic review and economic modelling

BACKGROUND

Coeliac disease is an autoimmune disorder triggered by ingesting gluten. It affects approximately 1% of the UK population, but only one in three people is thought to have a diagnosis. Untreated coeliac disease may lead to malnutrition, anaemia, osteoporosis and lymphoma.

OBJECTIVES

The objectives were to define at-risk groups and determine the cost-effectiveness of active case-finding strategies in primary care.

DESIGN

(1) Systematic review of the accuracy of potential diagnostic indicators for coeliac disease. (2) Routine data analysis to develop prediction models for identification of people who may benefit from testing for coeliac disease. (3) Systematic review of the accuracy of diagnostic tests for coeliac disease. (4) Systematic review of the accuracy of genetic tests for coeliac disease (literature search conducted in April 2021). (5) Online survey to identify diagnostic thresholds for testing, starting treatment and referral for biopsy. (6) Economic modelling to identify the cost-effectiveness of different active case-finding strategies, informed by the findings from previous objectives.

DATA SOURCES

For the first systematic review, the following databases were searched from 1997 to April 2021: MEDLINE® (National Library of Medicine, Bethesda, MD, USA), Embase® (Elsevier, Amsterdam, the Netherlands), Cochrane Library, Web of Science™ (Clarivate™, Philadelphia, PA, USA), the World Health Organization International Clinical Trials Registry Platform ( WHO ICTRP ) and the National Institutes of Health Clinical Trials database. For the second systematic review, the following databases were searched from January 1990 to August 2020: MEDLINE, Embase, Cochrane Library, Web of Science, Kleijnen Systematic Reviews ( KSR ) Evidence, WHO ICTRP and the National Institutes of Health Clinical Trials database. For prediction model development, Clinical Practice Research Datalink GOLD, Clinical Practice Research Datalink Aurum and a subcohort of the Avon Longitudinal Study of Parents and Children were used; for estimates for the economic models, Clinical Practice Research Datalink Aurum was used.

REVIEW METHODS

For review 1, cohort and case-control studies reporting on a diagnostic indicator in a population with and a population without coeliac disease were eligible. For review 2, diagnostic cohort studies including patients presenting with coeliac disease symptoms who were tested with serological tests for coeliac disease and underwent a duodenal biopsy as reference standard were eligible. In both reviews, risk of bias was assessed using the quality assessment of diagnostic accuracy studies 2 tool. Bivariate random-effects meta-analyses were fitted, in which binomial likelihoods for the numbers of true positives and true negatives were assumed.

RESULTS

People with dermatitis herpetiformis, a family history of coeliac disease, migraine, anaemia, type 1 diabetes, osteoporosis or chronic liver disease are 1.5-2 times more likely than the general population to have coeliac disease; individual gastrointestinal symptoms were not useful for identifying coeliac disease. For children, women and men, prediction models included 24, 24 and 21 indicators of coeliac disease, respectively. The models showed good discrimination between patients with and patients without coeliac disease, but performed less well when externally validated. Serological tests were found to have good diagnostic accuracy for coeliac disease. Immunoglobulin A tissue transglutaminase had the highest sensitivity and endomysial antibody the highest specificity. There was little improvement when tests were used in combination. Survey respondents (n = 472) wanted to be 66% certain of the diagnosis from a blood test before starting a gluten-free diet if symptomatic, and 90% certain if asymptomatic. Cost-effectiveness analyses found that, among adults, and using serological testing alone, immunoglobulin A tissue transglutaminase was most cost-effective at a 1% pre-test probability (equivalent to population screening). Strategies using immunoglobulin A endomysial antibody plus human leucocyte antigen or human leucocyte antigen plus immunoglobulin A tissue transglutaminase with any pre-test probability had similar cost-effectiveness results, which were also similar to the cost-effectiveness results of immunoglobulin A tissue transglutaminase at a 1% pre-test probability. The most practical alternative for implementation within the NHS is likely to be a combination of human leucocyte antigen and immunoglobulin A tissue transglutaminase testing among those with a pre-test probability above 1.5%. Among children, the most cost-effective strategy was a 10% pre-test probability with human leucocyte antigen plus immunoglobulin A tissue transglutaminase, but there was uncertainty around the most cost-effective pre-test probability. There was substantial uncertainty in economic model results, which means that there would be great value in conducting further research.

LIMITATIONS

The interpretation of meta-analyses was limited by the substantial heterogeneity between the included studies, and most included studies were judged to be at high risk of bias. The main limitations of the prediction models were that we were restricted to diagnostic indicators that were recorded by general practitioners and that, because coeliac disease is underdiagnosed, it is also under-reported in health-care data. The cost-effectiveness model is a simplification of coeliac disease and modelled an average cohort rather than individuals. Evidence was weak on the probability of routine coeliac disease diagnosis, the accuracy of serological and genetic tests and the utility of a gluten-free diet.

CONCLUSIONS

Population screening with immunoglobulin A tissue transglutaminase (1% pre-test probability) and of immunoglobulin A endomysial antibody followed by human leucocyte antigen testing or human leucocyte antigen testing followed by immunoglobulin A tissue transglutaminase with any pre-test probability appear to have similar cost-effectiveness results. As decisions to implement population screening cannot be made based on our economic analysis alone, and given the practical challenges of identifying patients with higher pre-test probabilities, we recommend that human leucocyte antigen combined with immunoglobulin A tissue transglutaminase testing should be considered for adults with at least a 1.5% pre-test probability of coeliac disease, equivalent to having at least one predictor. A more targeted strategy of 10% pre-test probability is recommended for children (e.g. children with anaemia).

FUTURE WORK

Future work should consider whether or not population-based screening for coeliac disease could meet the UK National Screening Committee criteria and whether or not it necessitates a long-term randomised controlled trial of screening strategies. Large prospective cohort studies in which all participants receive accurate tests for coeliac disease are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019115506 and CRD42020170766.

FUNDING

This project was funded by the National Institute for Health and Care Research ( NIHR ) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 44. See the NIHR Journals Library website for further project information.

Isolated positive deamidated gliadin peptide-IgG has limited diagnostic utility in coeliac disease

AIM

Deamidated gliadin peptide-IgG (DGP-IgG) antibody serology testing is widely utilised in screening for coeliac disease in Australia; however, it is used sparingly in Europe. The aim of this study was to assess the diagnostic value of a positive DGP-IgG in the setting of a negative tissue transglutaminase-IgA (tTG-IgA) for gastrointestinal pathology among paediatric patients.

METHODS

We conducted a retrospective cohort study of all children with an elevated DGP-IgG in the setting of a negative tTG-IgA who underwent gastroscopy over a 48-month period (January 2015-December 2018) at a tertiary paediatric centre. They were identified utilising the electronic pathology database and demographic and clinical data were collected from electronic medical records. Patients who had previously been diagnosed with coeliac disease were on a gluten-free diet or over the age of 18 were excluded from the study.

RESULTS

Twenty-six patients with an elevated DGP-IgG in the setting of a negative tTG-IgA underwent gastroscopy. Our study yielded a positive predictive value of 1/26 (3.9% CI 95% 0.7%, 18.9%) for the diagnosis of coeliac disease. Overall, there were 25 histopathological diagnoses including 1 diagnosis of coeliac disease among the total 26 patients who were positive DGP-IgG and negative tTG-IgA and underwent gastroscopy.

CONCLUSIONS

Our findings suggest that an isolated positive DGP-IgG has a very low diagnostic yield for coeliac disease in children and may be indicative of other gastrointestinal pathology.

Diagnostic Value of Immunoglobulin G Anti-Deamidated Gliadin Peptide Antibody for Diagnosis of Pediatric Celiac Disease: A Study from Shiraz, Iran

PURPOSE

Screening serologic tests are important tools for the diagnosis of celiac disease (CD). Immunoglobulin (Ig)G anti-deamidated gliadin peptide (anti-DGP) is a relatively new autoantibody thought to have good diagnostic accuracy, comparable to that of anti-tissue transglutaminase (anti-tTG) antibody.

METHODS

Pediatric patients (n=86) with a clinical suspicion of CD were included. Duodenal biopsy, anti-tTG, and IgG anti-DGP antibody tests were performed. The patients were divided into CD and control groups based on the pathological evaluation of duodenal biopsies. The diagnostic accuracy of serological tests was determined.

RESULTS

IgA anti-tTG and IgG anti-DGP antibodies were positive in 86.3% and 95.4% of patients, respectively. The sensitivity, specificity, and diagnostic accuracy of the IgA anti-tTG test were 86.3%, 50.0%, and 68.6%, respectively, and those of the IgG anti-DGP test were 95.4%, 85.7%, and 90.7%, respectively. The area under the receiver operating characteristic (ROC) curve was 0.84 (95% confidence interval [CI], 0.74-0.91) for IgA anti-tTG test and 0.93 (95% CI, 0.86-0.97) for IgG anti-DGP test. The comparison of IgA anti-tTG and IgG anti-DGP ROC curves showed a higher sensitivity and specificity of the IgG anti-DGP test.

CONCLUSION

IgG anti-DGP is a reliable serological test for CD diagnosis in children. High tTG and DGP titers in the serum are suggestive of severe duodenal atrophy. The combined use of IgA anti-tTG and IgG anti-DGP tests for the initial screening of CD can improve diagnostic sensitivity.

Diagnostic Accuracy of IgA Anti-Transglutaminase and IgG Anti-Deamidated Gliadin for Diagnosis of Celiac Disease in Children under Two Years of Age: A Systematic Review and Meta-Analysis

The need of adding the determination of anti-deamidated gliadin peptide (DGP) IgG to anti-transglutaminase (TTG) IgA antibodies for diagnosis of celiac disease (CD) in children <2 years of age is controversial. We performed a systematic review and meta-analysis to evaluate, by head-to-head comparison, the diagnostic accuracy of TTG IgA and DGP IgG antibodies. We searched PubMed, MEDLINE, and Embase databases up to January 2021. The diagnostic reference was intestinal biopsy. We calculated the sensitivity and specificity of these tests and the odds ratio (OR) between the tests. Fifteen articles were eligible for the systematic review and ten were eligible for the meta-analysis. Sensitivity and specificity were 0.96 (95% confidence interval (CI), 0.91–0.98) and 0.96 (95% CI, 0.85–0.99) for DGP IgG and 0.93 (95% CI, 0.88–0.97) and 0.98 (95% CI, 0.96–0.99) for TTG IgA, respectively. TTG IgA specificity was significantly higher (OR 9.3 (95% CI, 2.3–37.49); p < 0.001) while the sensitivity of DGP IgG was higher without reaching statistical significance (OR: 0.6 (95% CI, 0.24–1.51); p = 0.28). Both the meta-analysis and the systematic review showed that some children with early CD are missed without the DGP IgG test. In children <2 years of age, TTG IgA is the best CD screening test; however, the addition of DGP IgG may increase the diagnostic sensitivity.

S2k guidelines (consensus statement) for diagnosis and therapy of dermatitis herpetiformis initiated by the European Academy of Dermatology and Venereology (EADV)

INTRODUCTION

Dermatitis herpetiformis (DH) is a chronic, pruritic, gluten-induced skin disorder characterized by subepidermal granular IgA deposition and a variable degree of enteropathy identical to that seen in coeliac disease. So far, there has been no European consensus about the management of DH.

METHODS

The guidelines were created by small subgroups of a guideline committee consisting of 26 specialists from various medical fields and one patients' representative. The members of the committee then discussed the guidelines and voted for the final version at two consensus meetings. The guidelines were developed under the support of the European Academy of Dermatology and Venereology (EADV) and in collaboration with the European Dermatology Forum (EDF).

RESULTS

The guidelines summarize evidence-based and expert-based recommendations (S2 level) for the management of DH (see Appendix).

CONCLUSION

These guidelines will improve the quality of management of DH and support dermatologists in their diagnostic and therapeutic decisions.

Deamidated Gliadin Antibodies: Do They Add to Tissue Transglutaminase-IgA Assay in Screening for Celiac Disease?

OBJECTIVES

Use of deamidated gliadin peptide (DGP) test kits as adjunctive to tissue-transglutaminase-IgA (TTG-IgA) for the diagnosis of celiac disease (CD) has been a controversial issue. The objectives of our study were to evaluate the diagnostic performance of DGP antibodies compared with TTG-IgA and to evaluate the correlation between DGP-antibody titers and degree of enteropathy.

METHODS

We included children who underwent endoscopy and biopsies because of positivity of any of the serology tests in the "celiac profile" (TTG-IgA, DGP-IgA, and DGP-IgG) from 2012 to 2019. We divided children into clinically suspected cases of CD (group 1) and asymptomatic cases screened as they were from a high-risk group (group 2).

RESULTS

Group 1 constituted 52 children and group 2 included 81 children (76 type-1 diabetes [T1D]). The sensitivity and positive-predictive value (PPV) of DGP-IgG in group 1 (90%, 98%) and group 2 (91%, 85.5%) were comparable with TTG-IgA (98%, 92% in group 1; 100%, 80% in group 2). By adding DGP-IgG to TTG-IgA, the performance of TTG-IgA has improved marginally in group 1 (sensitivity 100%, PPV 92.3%). All cases with DGP-IgG titer 2 times ULN in group 1, and >4 times ULN in group 2 had villous atrophy. All T1D patients with TTG IgA >10 times ULN had villous atrophy.

CONCLUSIONS

DGP-IgG assay did not add to the performance of TTG-IgA. DGP-IgG titer correlated with enteropathy. The diagnosis of CD can be made in asymptomatic T1D child with TTG-IgA titer >10 times ULN and positive endomyseal antibodies.

Antibodies against neo-epitope of microbial and human transglutaminase complexes as biomarkers of childhood celiac disease

Tissue transglutaminase (tTG) and microbial transglutaminase (mTG) cross-link gliadins to form complexes that expose immunogenic neo-epitopes to produce tTG and mTG-neo-epitope antibodies. The aim of this study was to test the diagnostic performance of antibodies against non-complexed and complexed forms of transglutaminases, to correlate their activities to the intestinal damage and to explore age group dependency in celiac disease (CD). A total of 296 children with untreated CD and 215 non-celiac disease controls were checked by in-house enzyme-linked immunosorbent assays detecting immunoglobulin (Ig)A, IgG or combined detection of IgA and IgG (check) against tTG, AESKULISA® tTG New Generation (tTG-neo) and mTG-neo (RUO), IgA and IgG antibodies against deamidated gliadin peptide (DGP) and human IgA anti-endomysium antibodies (EMA) using AESKUSLIDES® EMA. Intestinal pathology was graded according the revised Marsh criteria, and age dependencies of the antibody activities were analysed. Using cut-offs estimated from receiver operating characteristic (ROC) curves, the highest area under curve (AUC) of the TG assays was 0·963 for tTG-neo check, followed by tTG check (0·962) when the diagnosis was based on enteric mucosal histology. tTG-neo check was the most effective to reflect the intestinal abnormalities in CD (r = 0·795, P < 0·0001). High levels of anti-mTG-neo IgG and anti-tTG-neo IgG appeared in the earlier age groups, as compared to anti-tTG IgG (P < 0·001). Considering antibody diagnostic performance based on AUC, enteric damage reflection and predictability at an early age, the anti-neo tTG check was the most effective diagnostic biomarker for pediatric CD. The mTG neo check might represent a new marker for CD screening, diagnosis and predictability.

European Society Paediatric Gastroenterology, Hepatology and Nutrition Guidelines for Diagnosing Coeliac Disease 2020

OBJECTIVES

The ESPGHAN 2012 coeliac disease (CD) diagnostic guidelines aimed to guide physicians in accurately diagnosing CD and permit omission of duodenal biopsies in selected cases. Here, an updated and expanded evidence-based guideline is presented.

METHODS

Literature databases and other sources of information were searched for studies that could inform on 10 formulated questions on symptoms, serology, HLA genetics, and histopathology. Eligible articles were assessed using QUADAS2. GRADE provided a basis for statements and recommendations.

RESULTS

Various symptoms are suggested for case finding, with limited contribution to diagnostic accuracy. If CD is suspected, measurement of total serum IgA and IgA-antibodies against transglutaminase 2 (TGA-IgA) is superior to other combinations. We recommend against deamidated gliadin peptide antibodies (DGP-IgG/IgA) for initial testing. Only if total IgA is low/undetectable, an IgG-based test is indicated. Patients with positive results should be referred to a paediatric gastroenterologist/specialist. If TGA-IgA is ≥10 times the upper limit of normal (10× ULN) and the family agrees, the no-biopsy diagnosis may be applied, provided endomysial antibodies (EMA-IgA) will test positive in a second blood sample. HLA DQ2-/DQ8 determination and symptoms are not obligatory criteria. In children with positive TGA-IgA <10× ULN at least 4 biopsies from the distal duodenum and at least 1 from the bulb should be taken. Discordant results between TGA-IgA and histopathology may require re-evaluation of biopsies. Patients with no/mild histological changes (Marsh 0/I) but confirmed autoimmunity (TGA-IgA/EMA-IgA+) should be followed closely.

CONCLUSIONS

CD diagnosis can be accurately established with or without duodenal biopsies if given recommendations are followed.

Misuse of serological screening tests for celiac disease in children: A prospective study in Italy

BACKGROUND

Despite a well-established diagnostic algorithm for celiac disease, it remains unclear whether prescriptions for celiac serological tests comply with the current pediatric guidelines.

AIM

To analyze the appropriateness of test prescription in children investigated for celiac disease in Italy, compared to the current European pediatric guidelines.

METHODS

All children who had performed a first evaluation for celiac disease were prospectively enrolled. Prescribed tests and related indications for testing were recorded, and compared to the European pediatric guidelines.

RESULTS

Overall, 202 children were enrolled (females 59%, mean age 7.1 years ±4.1) in two centers. The reasons for celiac disease testing were typical, atypical symptoms or celiac disease-associated conditions in 46.5%, 49%, and 4.5% of cases, respectively. First-line tests were IgA and IgG anti-transglutaminase antibodies in 88.1% and 29.7% of children, IgA and IgG anti-deamidated gliadin peptide antibodies in 43% and 47%, IgA and IgG anti native gliadin in 15.8%, IgA anti-endomysium antibodies in 44.5%, HLA predisposing genes in 10% of patients. Test redundancy was very common, and the current diagnostic guidelines were correctly followed only in 23/202 patients (11.4%).

CONCLUSIONS

Diagnostic European guidelines for celiac disease screening are often disregarded in Italy. Intervention to implement adherence to these guidelines is needed, with the aim of improving resource utilization, and quality of patient care.

Celiac Disease: Clinical Features and Diagnosis

The presentation in celiac disease is shifting from the classical malabsorptive presentation to more nonclassical presentations, requiring clinicians to maintain a high level of suspicion for the disease and to be aware of the possible extraintestinal manifestations. The diagnosis of celiac disease is guided by initial screening with serology, followed by confirmation with an upper endoscopy and small intestinal biopsy. In some pediatric cases, biopsy may be avoided.

Systematic Literature Review of the Economic Burden of Celiac Disease

BACKGROUND

The prevalence of celiac disease (CD) has rapidly increased over recent decades, but costs related to CD remain poorly quantified.

OBJECTIVE

This systematic review assessed the economic burden of CD in North America and Europe.

METHODS

MEDLINE, EMBASE, EconLit, and the Cochrane Library databases were systematically searched to identify English-language literature from 2007 to 2018 that assessed costs, cost effectiveness, and health resource utilization for CD.

RESULTS

Forty-nine studies met the inclusion criteria, of which 28 (57.1%) addressed costs of testing and diagnosis; 33 (67.3%) were from Europe. The cost per positive CD diagnosis of testing patients already undergoing esophagogastroduodenoscopy for other indications ranged from 1300 Canadian dollars ($Can) in Canada (2016 value) to €44,712 in the Netherlands (2013 value). Adding the CD test was cost effective when it combined diagnostic modalities (e.g., serology and biopsy). Direct annual excess costs to a US payer per diagnosed CD patient totaled $US6000 (2013 value) more than for a person without CD, chiefly due to outpatient care. Hospitalizations, emergency visits, and medication use were more common with CD. After initiating a gluten-free diet (GFD), patients visited primary care providers less often, used more medications, and missed fewer days from school and work.

CONCLUSIONS

Most of the few available economic studies of CD assess testing and diagnosis costs, especially in Europe. Methods of testing generally are considered cost effective when they combine diagnostic modalities in symptomatic patients. Most costs to a payer of managing CD derive from outpatient care. Following GFD initiation, patients lose fewer days from work and school than pretreatment.

In Screening for Celiac Disease, Deamidated Gliadin Rarely Predicts Disease When Tissue Transglutaminase Is Normal

OBJECTIVE

While tissue transglutaminase (tTG) antibodies are the most established serological test for celiac disease, newer deamidated gliadin peptide (DGP) screening tests are increasingly being completed. No pediatric study has systematically assessed the incidence of celiac disease in patients with an isolated positive DGP result. We sought to determine the positive predictive value of DGP serology for biopsy-confirmed celiac disease in pediatric patients with elevated DGP and normal tTG, to help guide clinicians' decision making when screening for this common condition and avoid unnecessary invasive follow-up diagnostic testing.

METHODS

A multicenter retrospective review of children, from birth to age 18, with isolated DGP immunoglobulin G (IgG) positive serology referred to 3 Canadian centers was completed. The positive predictive value of an isolated elevated DGP result was calculated.

RESULTS

Forty patients with DGP positive, tTG negative serology underwent endoscopy with duodenal biopsy. Of these, only 1 patient had biopsy-confirmed celiac disease. This patient was IgA deficient. This yields a positive predictive value of 2.5% (95% confidence interval 0.1%-14.7%) for isolated DGP IgG positive serology.

CONCLUSIONS

In isolation, DGP positive serology has a poor positive predictive value for celiac disease in children, especially in IgA sufficient individuals. Our findings suggest that DGP IgG testing should not be completed as part of the initial screening for celiac disease in the pediatric population as it does not effectively differentiate between individuals with and without the disease. Further research is needed to clarify to role of DGP IgG in children under the age of 2 and those with IgA deficiency.

Will the Real Coeliac Disease Please Stand Up? Coeliac Disease Prevalence in the German LIFE Child Study

OBJECTIVES

Assessing the seroprevalence and the prevalence of definite coeliac disease (CD) in the German LIFE Child Health study cohort including immunoglobulin A (IgA) antibodies against tissue transglutaminase (IgA-TTG) in addition to IgG antibodies against deamidated gliadin peptides (IgG-DGP) and human leukocyte antigen (HLA)-DQ2/8 genotyping.

METHODS

Samples from children and adolescents were first screened for IgA-TTG and IgG-DGP. If IgA-TTG was above 0.5 times the upper limit of normal and/or IgG-DGP was positive, IgA antibodies against endomysium (IgA-EmA) were measured, and HLA was genotyped. In patients with only IgG-DGP positivity, total IgA was assayed. Subjects with suspicious results were followed up serologically and, in case of repeatedly positive antibody results, invited for a personal interview. Further diagnostic data were obtained independent from our study.

RESULTS

We screened 2363 children's blood samples collected from 2011 to 2015. The seroprevalence, that is, IgA-TTG and/or IgA-EmA positivity or IgG-DGP positivity with IgA <0.05 g/L, was 1.57% (95% confidence interval [CI95%] 1.14-2.15). The prevalence of suspected CD, that is, seroprevalence and compatible HLA genotype with hitherto unknown mucosal damage, was 1.35% (CI95% 0.96-1.91). Definite CD, that is, seropositivity accompanied by positive intestinal biopsy or IgA-TTG ≥ 10 × upper limit of normal, was found in 0.42% (CI95% 0.22-0.80). Seven children claimed to have CD. The HLA haplotype, however, matched in only 4 of them resulting in an overall CD prevalence of at least 0.59% (CI95% 0.34-1.02). Thirteen unclear cases remained; therefore, the prevalence may even be higher.

CONCLUSIONS

The prevalence of definite CD in a population-representative German cohort is higher than previously described. HLA-DQ typing is helpful to identify false-positive IgA-TTG patients negative for IgA-EmA and/or IgG-DGP under screening conditions and unmasks possible misdiagnoses of CD.

Prevalence of Celiac Disease Autoimmunity Among Adolescents and Young Adults in China

BACKGROUND & AIMS

In China, epidemiologic information on celiac disease autoimmunity is scarce and fragmented. We investigated the prevalence of celiac disease autoimmunity in the general Chinese population.

METHODS

In a cross-sectional prospective study, 19,778 undiagnosed Chinese adolescents and young adults (age, 16-25 y) were recruited from consecutive new students who underwent routine physical examinations at 2 universities in Jiangxi, China, from September 2010 through October 2013; the students were from 27 geographic regions in China. All subjects were tested for serum IgG, IgG against deamidated gliadin peptides (IgG anti-DGP), and IgA anti-tissue transglutaminase antibodies (IgA anti-tTG). We also analyzed HLA genotypes in subgroups of participants with different results from tests for serum markers of celiac disease.

RESULTS

A total of 434 students (2.19%) tested positive for serum markers for celiac disease (95% confidence interval [CI], 1.99%-2.41%), 0.36% of the students tested positive for anti-tTG IgA (95% CI, 0.28%-0.46%), and 1.88% tested positive for anti-DGP IgG (95% CI, 1.70%-2.09%). The prevalence of celiac disease autoimmunity (positive results in assays for anti-tTG IgA and anti-DGP-IgG) was 0.06% (95% CI, 0.03%-0.10%). Celiac disease autoimmunity was associated with the consumption of wheat and female sex. The prevalence in the Shandong province in north China, where wheat is a staple in the diet, was 0.76% (95% CI, 0.21%-1.95%). The frequencies of the HLA-DQ2/-DQ8 genotypes associated with celiac disease were higher in subjects with celiac disease autoimmunity, based on detection of both serum markers, than in subjects with positive results from a single test (P < .01). All subjects with positive results from both assays carried the HLA-DQ2 genotype.

CONCLUSIONS

Approximately 2% of adolescents or young adults in China had positive results from assays for serum markers for celiac disease. The prevalence of celiac disease autoimmunity in the Shandong province in north China, where wheat is a staple in the diet, was 0.76%.

Coeliac disease in infants: antibodies to deamidated gliadin peptide come first!

Background

The onset of coeliac disease (CD) in the first year of life is uncommon and the diagnosis can be challenging due to the suboptimal sensitivity of tissue transglutaminase antibodies (tTG) at this age and the many other possible causes of malabsorption in infants. Antibodies to deamidated gliadin peptides (anti-DGPs), especially IgG, may appear earlier than IgA anti-tTG in very young children with CD.

Case presentation

We report here on an 8-month-old child who was evaluated for failure to thrive, constipation and developmental delay. The symptoms started following gluten introduction in the diet. Laboratory tests showed high fecal elastase concentration, normal serum IgA levels with positive IgG and IgA anti-DGPs, whereas anti-tTG were not detected. The duodenal biopsy revealed a complete villous atrophy (Marsh-Oberhuber 3C). The culture of biopsy fragments in the presence of gliadin peptides did not stimulate the production of IgA anti-endomysial antibodies. Genetic testing proved the child was positive for HLA-DQ2 (DQA1*05; DQB1*02) and HLA-DQ8 (DQA1*03, DQB1*0302). Having initiated the gluten-free diet, the symptoms disappeared and the infant experienced rapid catch-up growth with normalization of psychomotor development.

Conclusions

This case report highlights the utility of anti-DGPs for screening infants with suspected CD. The pattern with positivity for IgG and IgA anti-DGPs only is rare in IgA-competent children with biopsy-proven CD. It could be explained in infancy as immaturity of the adaptive immune system.

Identification of Pediatric Patients With Celiac Disease Based on Serology and a Classification and Regression Tree Analysis

BACKGROUND & AIMS

Celiac disease is detected using serology and endoscopy analyses. We used multiple statistical analyses of a geographically isolated population in the United States to determine whether a single serum screening can identify individuals with celiac disease.

METHODS

We performed a retrospective study of 3555 pediatric patients (18 years old or younger) in the intermountain West region of the United States from January 1, 2008, through September 30, 2013. All patients had undergone serologic analyses for celiac disease, including measurement of antibodies to tissue transglutaminase (TTG) and/or deamidated gliadin peptide (DGP), and had duodenal biopsies collected within the following year. Modified Marsh criteria were used to identify patients with celiac disease. We developed models to identify patients with celiac disease using logistic regression and classification and regression tree (CART) analysis.

RESULTS

Single use of a test for serum level of IgA against TTG identified patients with celiac disease with 90% sensitivity, 90% specificity, a 61% positive predictive value (PPV), a 90% negative predictive value, and an area under the receiver operating characteristic curve value of 0.91; these values were higher than those obtained from assays for IgA against DGP or IgG against TTG plus DGP. Not including the test for DGP antibody caused only 0.18% of celiac disease cases to be missed. Level of TTG IgA 7-fold the upper limit of normal (ULN) identified patients with celiac disease with a 96% PPV and 100% specificity. Using CART analysis, we found a level of TTG IgA 3.2-fold the ULN and higher to most accurately identify patients with celiac disease (PPV, 89%). Multivariable CART analysis showed that a level of TTG IgA 2.5-fold the ULN and higher was sufficient to identify celiac disease in patients with type 1 diabetes (PPV, 88%). Serum level of IgA against TTG in patients with versus those without trisomy 21 did not affect diagnosis predictability in CART analysis.

CONCLUSIONS

In a population-based study, we found that serum level of IgA against TTG can identify patients with celiac disease with PPVs of about 90%. Predictive values increase greatly when levels are markedly above the ULN or when the assay is used in combination with other variables. Measurement of IgG against TTG or DGP does not increase the accuracy of detection of celiac disease based against TTG IgA levels. There is a low risk of false-positive results from serologic analysis in patients with type I diabetes or persistent increases in antibody against TTG on repeat testing.

Interpretation of serological tests in the diagnosis of celiac disease: Anti-deamidated gliadin peptide antibodies revisited

Algorithms for celiac disease diagnosis provided by guidelines are based primarily on anti-tissue transglutaminase 2 (TG2) antibodies and/or anti-endomysium antibodies. The place of anti-deamidated gliadin peptide (DGP) antibodies is less well established. This study was designed to assess the clinical relevance of anti-DGP antibodies. Two thousand and twenty-six consecutive unselected patients systematically tested for anti-TG2, endomysium, gliadin, DGP antibodies and IgA dosage were investigated. The serological interpretation was assessed by analyzing the medical records of patients. From the 1984 newly investigated patients suspected of celiac disease, 10% had at least one celiac marker. Anti-TG2, anti-endomysium, anti-gliadin and anti-DGP antibodies were found in 1.1%, 0.6%, 6.8% and 4.1% of cases respectively, with different combinations. The diagnosis of celiac disease was retained in 0.45% of patients. When using the duodenal biopsies as a gold standard, analysis of the anti-DGP diagnosis performance showed that the specificity and the predictive positive value (PPV) were lower than that of the anti-TG2 assay. The combined detection of anti-TG2 and anti-DGP antibodies had a lower PPV than that of anti-TG2 and anti-endomysium antibodies (p = 0.04). When analyzing the contribution of anti-DGP antibodies as an additional marker to both anti-TG2 and anti-endomysium antibodies, the PPV of the three associated antibodies was shown to be significantly lower than the PPV of the both anti-TG2 and anti-endomysium antibodies (p = 0.04). As a conclusion, anti-DGP antibodies may not have the diagnosis value required as an additional screening test to anti-TG2 antibodies for identifying celiac disease patients in medical centers where anti-endomysium detection is available.

Simultaneous detection of IgA and IgG antibodies against tissue transglutaminase: The preferred pre-biopsy test in childhood celiac disease

OBJECTIVES

IgA antibodies against tissue transglutaminase (anti-TG2) is a reliable marker of celiac disease (CD). However, IgA-deficient patients are not identified and young children may lack IgA anti-TG2. Combined detection of IgA and IgG (IgA/IgG) against deamidated gliadin peptides (DGP) has shown a high diagnostic performance for untreated CD. Here we examined the utility of IgA/IgG anti-TG2, IgA/IgG anti-DGP and IgA/IgG against a mix of TG2 and DGP (anti-TG2/DGP) in finding CD among children.

METHODS

Serum antibodies against TG2, DGP, and TG2/DGP were determined with ELISA in 242 children referred to a paediatric gastroenterologist. Fifty had untreated CD verified by an intestinal biopsy and 192/242 children had other diseases than CD.

RESULTS

Forty-eight untreated CD children had increased IgA/IgG anti-TG2, 47/50 had increased IgA/IgG anti-DGP and 46/50 had increased IgA/IgG anti-TG2/DGP. One control subject had increased IgA/IgG anti-TG2 and IgA/IgG anti-TG2/DGP, whereas 7/192 control subjects had increased IgA/IgG anti-DGP. The IgA/IgG anti-TG2 assay had the best performance with a sensitivity of 96%, a specificity of 99.5% and the area under the ROC-curve was 0.996 (95% CI 0.992-1, p < 0.0001).

CONCLUSIONS

Detection of one antibody is not sufficient when screening for untreated CD among children due to cases of IgA deficiency. The inclusion of DGP antigens in the IgA/IgG combination assays seems to affect the sensitivity and specificity negatively, whereas detection of IgA/IgG anti-TG2 has the potential of finding most untreated CD patients, including those with IgA deficiency.

Prevalence of celiac disease autoimmunity in children with type 1 diabetes: regional variations across the Øresund strait between Denmark and southernmost Sweden

OBJECTIVES

The aim was to determine the prevalence of celiac disease autoimmunity in children with type 1 diabetes (T1D) diagnosed in Denmark and Sweden.

METHODS

A total of 662 Swedish children with T1D were matched with 1080 Danish children with T1D and 309 healthy children from Sweden and 283 from Denmark served as controls. Sera were analyzed for the presence of IgA and IgG (IgAG) autoantibodies against deamidated gliadin peptide (DGP) and tissue transglutaminase (tTG) with enzyme-linked immunosorbent assay (ELISA) and IgG-tTG separately in a radioligand binding assay (RBA). Human leukocyte antigen (HLA)-DQB1 and DQA1 genotyping were determined in the T1D cohorts.

RESULTS

In the Swedish T1D cohort, 17.2% (114/662) were IgAG-DGP/tTG positive compared with 11.7% (126/1080) in the Danish T1D cohort (p = 0.001) and with 9.4% (29/309) Swedish (p = 0.001) and 5.7% (16/283) Danish (p = 0.003) controls. In the Swedish T1D cohort, both levels of IgAG-DGP/tTG and IgG-tTG were higher compared with the levels in the Danish T1D (p < 0.001). In the control group, 2.8% of the Danish children were positive for both IgAG-DGP/tTG and IgG-tTG, compared to 0.3% of the Swedish. Presence of HLA-DQ2 was equally distributed among 89 children with T1D positive for both IgAG-DGP/tTG and IgG-tTG.

CONCLUSION

The discrepancy in levels of IgAG-DGP/tTG and IgG-tTG between Swedish and Danish T1D cohorts was independent of HLA and suggests that regional variations in comorbidity of celiac disease in T1D is caused by difference in exposure to environmental factors.

Antibodies to deamidated gliadin peptide in diagnosis of celiac disease in children

OBJECTIVES

Determination of antibodies to synthetic deamidated gliadin peptides (anti-DGPs) may work as an alternative or complement the commonly used test for tissue transglutaminase antibodies (TGA) in the diagnosis of celiac disease (CD). We analyzed the performance of a time-resolved immunofluorometric anti-DGP assay (TR-IFMA) in the diagnosis of CD in children and also retrospectively analyzed the appearance of anti-DGP antibodies before TGA seroconversion.

METHODS

The study included 92 children with biopsy-confirmed CD. Serum samples were taken at the time or just before the clinical diagnosis. The control group comprised 82 TGA-negative children who were positive for human leucocyte antigen-DQ2 or -DQ8.

RESULTS

Based on receiver operating characteristic curves, the optimal cutoff value for immunoglobulin (Ig) A anti-DGP positivity was 153 arbitrary units (AUs) with a sensitivity of 92.4% and specificity of 97.6% and that for IgG anti-DGP 119 AU, with a sensitivity of 97.8% and specificity of 97.6%. All 92 children with CD were either IgA or IgG anti-DGP positive at the time of diagnosis. Sera from 48 children with CD were also analyzed retrospectively before the diagnosis. Anti-DGP antibodies preceded TGA positivity in 35 of the 48 children with CD and appeared a median of 1 year earlier.

CONCLUSIONS

The TR-IFMA assay for detecting anti-DGP antibodies shows high sensitivity and specificity for the diagnosis of CD in children. In a majority of our study population, anti-DGP seropositivity preceded TGA positivity, indicating that earlier detection of CD may be possible by monitoring anti-DGP antibodies frequently in genetically susceptible children.

Overview of biomarkers for diagnosis and monitoring of celiac disease

Among the adverse reactions caused by wheat, celiac disease (CD) is the longest studied and best-known pathology. The more recently defined non-celiac gluten sensitivity (NCGS) presents with symptoms which are often indistinguishable from CD. Diagnosis of CD is based on serologic, molecular, and bioptic testing. The IgA anti-transglutaminase (tTG) test is considered highly important, as it shows high sensitivity and specificity and its levels correlate to the degree of intestinal damage. Small bowel biopsy can be avoided in symptomatic patients with IgA anti-tTG levels above 10× the manufacturer's cut-off. Recently, tests of anti-deamidated peptides of gliadin (DGP) have replaced classic anti-native gliadin (AGA) tests. DGP assays have a considerably higher diagnostic accuracy than AGA assays, especially in the IgG class, and can replace anti-tTG tests in patients with selective IgA deficiency. The combination of IgG anti-DGP plus IgA anti-tTG assays show greater sensitivity than a single test, with very high specificity. EMA tests have great diagnostic accuracy but are not recommended by all the latest guidelines because they are observer dependent. Biopsy must still be considered the gold standard for CD diagnosis. HLA-DQ genotyping can be used to screen asymptomatic children and in cases of histology/serology disagreement. About half of NCGS patients are DQ2 positive and have IgG AGA. To diagnose NCGS, first CD and wheat allergy must be excluded; then the wheat dependence of symptoms must be verified by a gluten-free diet and subsequent gluten challenge.

Celiac disease diagnosis: impact of guidelines on medical prescription in France

OBJECTIVE

Celiac disease is a complex autoimmune disease affecting patients of any age, who may present a wide variety of clinical manifestations. Different guidelines for the diagnosis and management of celiac disease have been recently published. The aim of this study was to determine whether the recommendations issued in these guidelines have been adopted by physicians in France when celiac disease was suspected.

METHODS

A total of 5521 physicians were asked to fill in a detailed questionnaire on diagnosing celiac disease to evaluate their medical practice, as to the type of symptoms leading to the suspicion of celiac disease, the prescription of duodenal biopsy or serological tests, the type of serological tests (anti-tissue transglutaminase, anti-endomysium, anti-gliadin and anti-reticulin antibodies, total immunoglobulin A measurement) prescribed to diagnose celiac disease.

RESULTS

The analysis of the responses of 256 general practitioners (GPs), 221 gastroenterologists and 227 pediatricians showed that the protean clinical presentations of celiac disease might be better recognized by gastroenterologists and pediatricians than by GPs. Gastroenterologists asked for duodenal biopsy much more often than GPs and pediatricians when celiac disease was suspected. Serological testing and knowledge of critical markers, prescribed to diagnose celiac disease, differed among GPs, gastroenterologists and pediatricians.

CONCLUSION

Analysis of medical prescriptions showed that the recommendations for celiac disease diagnosis are not necessarily followed by physicians, emphasizing the fact that the impact of national or international guidelines on medical behavior should be evaluated.

Antibodies in the diagnosis of coeliac disease: a biopsy-controlled, international, multicentre study of 376 children with coeliac disease and 695 controls

Diagnosis of coeliac disease (CD) relies on a combination of clinical, genetic, serological and duodenal morphological findings. The ESPGHAN suggested that biopsy may not be necessary in all cases. New guidelines include omission of biopsy if the concentration of CD-specific antibodies exceeds 10 times the upper limit of normal (10 ULN) and other criteria are met. We analysed the 10 ULN criterion and investigated multiple antibody-assays. Serum was collected from 1071 children with duodenal biopsy (376 CD patients, 695 disease-controls). IgA-antibodies to tissue transglutaminase (IgA-aTTG), IgG-antibodies to deamidated gliadin peptides (IgG-aDGL) and IgA-endomysium antibodies (IgA-EMA) were measured centrally. We considered 3 outcomes for antibody test procedures utilizing IgA-aTTG and/or IgG-aDGL: positive (≥10 ULN, recommend gluten-free diet), negative (<1 ULN, no gluten-free diet) or unclear (perform biopsy). Positive (PPV) and negative (NPV) predictive values were based on clear test results. We required that they and their lower confidence bounds (LCB) be simultaneously very high (LCB >90% and PPV/NPV >95%). These stringent conditions were met for appropriate antibody-procedures over a prevalence range of 9–57%. By combining IgG-aDGL with IgA-aTTG, one could do without assaying total IgA. The PPV of IgG-aDGL was estimated to be extremely high, although more studies are necessary to narrow down the LCB. The proportion of patients requiring a biopsy was <11%. The procedures were either equivalent or even better in children <2 years compared to older children. All 310 of the IgA-aTTG positive children were also IgA-EMA positive. Antibody-assays could render biopsies unnecessary in most children, if experienced paediatric gastroenterologists evaluate the case. This suggestion only applies to the kits used here and should be verified for other available assays. Confirming IgA-aTTG positivity (≥10 ULN) by EMA-testing is unnecessary if performed on the same blood sample. Prospective studies are needed.

Serological assessment for celiac disease in IgA deficient adults

PURPOSE

Selective immunoglobulin A deficiency is the most common primary immunodeficiency disorder that is strongly overrepresented among patients with celiac disease (CD). IgG antibodies against tissue transglutaminase (tTG) and deamidated gliadin peptides (DGP) serve as serological markers for CD in IgA deficient individuals, although the diagnostic value remains uncertain. The aim of this study was to investigate the prevalence of these markers in a large cohort of IgA deficient adults with confirmed or suspected CD and relate the findings to gluten free diet.

METHODS

Sera from 488,156 individuals were screened for CD in seven Swedish clinical immunology laboratories between 1998 and 2012. In total, 356 out of 1,414 identified IgA deficient adults agreed to participate in this study and were resampled. Forty-seven IgA deficient blood donors served as controls. Analyses of IgG antibodies against tTG and DGP as well as HLA typing were performed and a questionnaire was used to investigate adherence to gluten free diet. Available biopsy results were collected.

RESULTS

Out of the 356 IgA deficient resampled adults, 67 (18.8%) were positive for IgG anti-tTG and 79 (22.2%) for IgG anti-DGP, 54 had biopsy confirmed CD. Among the 47 IgA deficient blood donors, 4 (9%) were positive for IgG anti-tTG and 8 (17%) for anti-DGP. Four were diagnosed with biopsy verified CD, however, 2 of the patients were negative for all markers. Sixty-eight of 69 individuals with positive IgG anti-tTG were HLA-DQ2/DQ8 positive whereas 7 (18.9%) of the 37 individuals positive for IgG anti-DGP alone were not.

CONCLUSIONS

IgG anti-tTG seems to be a more reliable marker for CD in IgA deficient adults whereas the diagnostic specificity of anti-DGP appears to be lower. High levels of IgG antibodies against tTG and DGP were frequently found in IgA deficient adults despite adhering to gluten free diet.

Usefulness of symptoms to screen for celiac disease

OBJECTIVE

To describe the frequency of symptoms and associated conditions among screening-detected celiac disease (CD) cases and non-CD children and to evaluate questionnaire-based case-finding targeting the general population.

METHODS

In a population-based CD screening of 12-year-olds, children and their parents completed questionnaires on CD-associated symptoms and conditions before knowledge of CD status. Questionnaire data for those who had their CD detected in the screening (n = 153) were compared with those of children with normal levels of CD markers (n = 7016). Hypothetical case-finding strategies were also evaluated. Questionnaires were returned by 7054 (98%) of the children and by 6294 (88%) of their parents.

RESULTS

Symptoms were as common among screening-detected CD cases as among non-CD children. The frequency of children with screening-detected CD was similar when comparing the groups with and without any CD-related symptoms (2.1% vs 2.1%; P = .930) or CD-associated conditions (3.6% vs 2.1%; P = .07). Case-finding by asking for CD-associated symptoms and/or conditions would have identified 52 cases (38% of all cases) at a cost of analyzing blood samples for 2282 children (37%) in the study population.

CONCLUSIONS

The current recommended guidelines for finding undiagnosed CD cases, so-called active case-finding, fail to identify the majority of previously undiagnosed cases if applied in the general population of Swedish 12-year-olds. Our results warrant further studies on the effectiveness of CD case-finding in the pediatric population, both at the clinical and population-based levels.