Predictive value for coeliac disease of antibodies to gliadin, endomysium, and jejunum in patients attending for jejunal biopsy

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.

Progress in the serology-based diagnosis and management of adult celiac disease

Introduction: This article provides a comprehensive overview of the development and application of serological tests used routinely in clinical practice for the diagnosis and management of adult celiac disease.Areas covered: We summarize existing scientific literature related to anti-endomyseal, anti-tissue transglutaminase, and anti-deamidated gliadin peptide antibodies and detail the current and potential future applications of these tests in celiac disease.Expert commentary: Current serological tests in celiac disease have some of the best performance characteristics among disease-specific tests. However, in adult celiac disease, current diagnostic algorithms still rely on duodenal biopsies to confirm the diagnosis. A 'biopsy avoidance strategy' has been implemented in pediatric celiac disease. Future high-quality studies will help inform on whether this approach can be implemented into adult gastroenterology services. It is envisaged that the next 5 years will see an increasing reliance on serology in the diagnosis of adult celiac disease.

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.

Antibodies as predictors of autoimmune diseases and cancer

BACKGROUND

Autoantibodies targeted against a variety of self-antigens are detected in autoimmune diseases and cancer. Emerging evidence has suggested the involvement of environmental factors such as infections and xenobiotics, and some dietary proteins and their antibodies in the pathogenesis of many autoimmune diseases. These antibodies appear in the blood years before presentation of symptoms in various disorders. Therefore, these antibodies may be used as biomarkers for early detection of various diseases.

OBJECTIVE

To provide an overview of antibody arrays that are measured against different human tissue antigens, crossreactive epitopes of infectious agents, dietary proteins, and haptenic chemicals in autoimmune diseases and cancer.

METHOD

Microarray analysis of antigen-antibody reaction.

CONCLUSION

The application of these antibody arrays to human autoimmune disease is expanding and is allowing for the identification of patterns or antibody signatures, thus establishing the premises for increased sensitivity and specificity of prediction, as well as positive predictive values. The presence of these antibodies would not necessarily mean that a patient would definitely become sick but may give a percentage of risk for different conditions that may develop over future months or years. Using this high-throughput microarray method, it is possible to screen rapidly for dozens of autoantibodies at low cost. This is an important factor in the implementation of autoantibody testing as a routine part of medical examinations.

The characterization of the repertoire of wheat antigens and peptides involved in the humoral immune responses in patients with gluten sensitivity and Crohn's disease

Intestinal T cells from gluten sensitivity/celiac disease patients respond to a heterogeneous array of peptides. Our study extended this heterogeneity to humoral immune response to various wheat proteins and peptides in patients with gluten sensitivity or Crohn's disease. IgG and IgA antibodies in sera from those patients and healthy control subjects were measured against an array of wheat antigens and peptides. In gluten-sensitive patients, IgG reacted most against transglutaminase, prodynorphin, wheat extract, and α-, γ-, and ω-gliadin; IgA reacted most against wheat then transglutaminase, glutenin, and other peptides. In the sera of Crohn's disease patients, IgG reacted most against wheat and wheat germ agglutinin then transglutaminase, prodynorphin, α-, and γ-gliadin; IgA reacted foremost against prodynorphin then transglutaminase and α-gliadin. These results showed a substantial heterogeneity in the magnitude of IgG and IgA response against various wheat antigens and peptides. Measurements of IgG and IgA antibodies against such an array of wheat peptides and antigens can enhance the sensitivity and specificity of serological assays for gluten sensitivity and celiac disease and may also detect silent celiac disease or its overlap with inflammatory bowel disease.

What is the use of biopsy and antibodies in coeliac disease diagnosis?

The advent of highly sensitive and specific serological markers has led to some protagonists proposing that coeliac disease can be diagnosed without the need for a biopsy. However, this is an area of controversy. Lack of consensus about diagnostic degrees of histological change, paucity of symptoms, antibody-negative disease and immunodeficiency can make diagnosis difficult even with a biopsy. Conversely, an argument can be put forward for a 'no biopsy' approach based on the large number of patients with typical symptoms and positive serology who experience a diagnostic delay. In addition, endoscopy is not without discomfort. This article discusses the use of antibodies and duodenal biopsy within this context. Finally, we propose a pragmatic diagnostic algorithm for clinicians to use when investigating patients for coeliac disease.

Antibodies as Predictors of Complex Autoimmune Diseases

Emerging evidence has suggested environmental factors such as infections and xenobiotics and some dietary proteins and peptides in the pathogenesis of many autoimmune diseases. Considering the fact that autoantibodies can often be detected prior to the onset of a disease, in this study an enzyme immunoassay was used for measurement of antibodies against different highly purified antigens or synthetic peptides originating not only from human tissue, but also from cross-reactive epitopes of infectious agents, dietary proteins and xenobiotics. The measurement of antibodies against a panel of antigens allows for identification of patterns or antibody signatures, rather than just one or two markers of autoimmunity, thus establishing the premise for increased sensitivity and specificity of prediction, as well as positive predictive values. This panel of different autoantibodies was applied to 420 patients with different autoimmune diseases, including pernicious anemia, celiac disease, thyroiditis, lupus, rheumatoid arthritis, osteoarthritis, Addison's disease, type 1 diabetes, cardiovascular disease and autoimmunity, which are presented in this article. In all cases, the levels of these antibodies were significantly elevated in patients versus controls. Antibody patterns related to neuroautoimmune disorders, cancer, and patients with somatic hypermutation will be shown in a subsequent article. We believe that this novel 96 antigen-specific autoantibody or predictive antibody screen should be studied for its incorporation into routine medical examinations. Clinicians should be aware that the detection of antibodies should not automatically mean that a patient will definitely become ill, but would rather give a percentage of risk for autoimmune disease over subsequent months or years.

The Immunology of Immediate and Delayed Hypersensitivity Reaction to Gluten

The immunology of gluten hypersensitivity and celiac disease has been pursued with significant interest in the past 20 years. For the prevention of systemic diseases, most pathogens that gain entry into our bodies must be met with an effective immune response, yet in the gastrointestinal tract it is equally important that commensal bacteria and a diverse collection of dietary proteins and peptides be recognized without eliciting an active immune response or constant activation of the inflammatory pathway. This phenomenon of hyporesponsiveness to food antigens is known as oral tolerance. This oral tolerance to dietary antigens is maintained by three different mechanisms: anergy, cell deletion and immune suppression. However, in the presence of mechanical/chemical stressors and infections, this tolerance may break down, and gut associated lymphoid tissues (GALT) will react to different luminal antigens. The reaction of GALT to these antigens may lead to the production of pro-inflammatory cytokines, opening of tight junctions, entry of undigested antigens into the circulation, and the subsequent production of IgA, IgG, IgM and IgE antibodies in blood and secretory components. Like any other food hypersensitivity reaction, gluten sensitivity can be divided into immediate and delayed hypersensitivities. In this review an attempt is made first to differentiate immediate hypersensitivity to gliadin, mediated by IgE, from delayed hypersensitivity, which is mediated by IgA and IgG. Furthermore, we attempt to differentiate between gluten hypersensitivity with enteropathy (celiac disease) and gluten hypersensitivity without enteropathy.

Determinants of endomysial antibody status in untreated coeliac disease

BACKGROUND

Serum endomysial antibody (EMA) is a highly specific marker of untreated coeliac disease (CD). The published estimates of sensitivity however vary widely and the explanation for this remains unclear.

OBJECTIVE

To determine the relative prevalence of EMA-negative CD and to identify clinical and histological characteristics which relate to EMA status.

METHOD

Retrospective analysis of prospectively collected data on incident cases of CD in a single hospital over a 10-year period with determination of EMA status before gluten withdrawal.

RESULTS

From a total of 241 participants, 37 [15% (95% confidence interval: 11, 20%)] were EMA negative, of whom only four were IgA deficient. EMA-positive and EMA-negative patients shared a number of characteristics including female predominance and a high prevalence of HLA DQ2. EMA status was associated with age-test sensitivity and exceeded 98% below the age of 35 years, falling to around 80% in older age groups overall, and lower still in current cigarette smokers. EMA status was not influenced by sex, family history of CD, other autoimmune disease, or by potential clinical or histological markers of disease severity.

CONCLUSION

A substantial proportion of patients with true CD are EMA negative. This has implications for the pathogenesis of the disease. It also limits the value of EMA as a screening test, particularly in older adults and cigarette smokers.

Antibodies against synthetic deamidated gliadin peptides as predictors of celiac disease: prospective assessment in an adult population with a high pretest probability of disease

BACKGROUND

Noninvasive serologic tests have shown high diagnostic accuracy for celiac disease (CD) in selected populations. Our aim was to determine prospectively the performance of CD-related serology in individuals undergoing intestinal biopsy because of clinical suspicion of small-bowel disorders.

METHODS

We enrolled 141 unselected consecutive adult patients attending a small-bowel disease clinic. Patients underwent endoscopy and biopsy; serum samples were obtained at that time for measurements of anti-tissue transglutaminase (a-tTG), IgA and IgG anti-deamidated gliadin-related peptide (a-DGP), and IgA antiactin antibodies (AAAs). Characterization of patients was based on histological criteria (Marsh type II lesion or greater).

RESULTS

The prevalence of CD was 42.5%. Sensitivity, specificity, and positive and negative predictive values were >90% for most assays. Diagnostic accuracy based on ROC curve analysis was similar for all assays [area under the curve (95% CI): 0.996 (0.967-0.998) for a-tTG, 0.995 (0.964-0.998) for IgA a-DGP, 0.989 (0.954-0.999) for IgG a-DGP, 0.996 (0.966-0.998) for blended conjugated of IgA + IgG a-DGP in a single assay, and 0.967 (0.922-0.990) for AAA]. The combinations of 2 tests, IgG a-DGP plus IgA a-tTG or the single blended conjugate detecting IgA + IgG a-DGP plus IgA a-tTG had 100% positive and negative predictive values if concentrations of both tests in either combination were above or below the cutoff.

CONCLUSIONS

In a population with high pretest probability, the newly developed a-DGP tests have diagnostic accuracy that is at least equivalent to that of established assays.

Endomysial antibody-negative coeliac disease: clinical characteristics and intestinal autoantibody deposits

BACKGROUND

Some patients with untreated coeliac disease are negative for serum endomysial autoantibodies (EmA) targeted against transglutaminase 2 (TG2).

AIMS

To evaluate the clinical and histological features of EmA-negative coeliac disease, and to examine whether EmA-equivalent autoantibodies against TG2 can be seen in the small-bowel mucosa when absent in serum.

PATIENTS

Serum EmA was studied in 177 biopsy-proved specimens from adult patients with coeliac disease. 20 patients with intestinal diseases served as non-coeliac controls; three had autoimmune enteropathy with villous atrophy.

METHODS

Clinical manifestations, small-bowel mucosal morphology, intraepithelial inflammation and TG2-specific extracellular immunoglobulin A (IgA) deposits were investigated in both serum EmA-negative and EmA-positive patients.

RESULTS

22 patients with IgA-competent coeliac disease were negative for serum EmA. Three of these had small-bowel lymphoma. Patients with EmA-negative coeliac disease were older, had abdominal symptoms more often, and the density of gammadelta+ intraepithelial lymphocytes in their intestinal mucosa was lower than in EmA-positive patients; otherwise the histology was similar. All serum EmA-negative patients with coeliac disease, but none of the disease controls, had gluten-dependent mucosal IgA deposits alongside TG2 in the small-bowel mucosal specimens. In vivo deposited IgA was shown to be TG2-specific by its ability to bind recombinant TG2.

CONCLUSIONS

Negative serum EmA might be associated with advanced coeliac disease. TG2-targeted autoantibodies were deposited in the small-bowel mucosa even when absent in serum. This finding can be used in the diagnosis of seronegative coeliac disease when the histology is equivocal. It may also be helpful in the differential diagnosis between autoimmune enteropathy and coeliac disease.

Prevalence of celiac disease in Brazilian children with type 1 diabetes mellitus

OBJECTIVE

Although the relationship between celiac disease and diabetes mellitus type 1 is well recognized, there are no studies of this association in Brazil. This study aims to identify the prevalence of celiac disease in a group of children with diabetes mellitus type 1 undergoing treatment in the pediatric endocrinology division of a university hospital in Minas Gerais, Brazil.

METHODS

Immunoglobulin (Ig)A and IgG antigliadin antibodies (enzyme-linked immunoadsorbent assay) were measured in blood collected from 236 children and adolescents with diabetes mellitus type 1. Patients with antigliadin antibodies then had jejunal biopsy and determination of antiendomysial antibodies by indirect immunofluorescence.

RESULTS

Twenty-one patients had IgA or IgG antigliadin antibodies. Nineteen underwent jejunal biopsy. Six had mucosal alterations compatible with celiac disease; four had nonspecific histologic changes; nine had normal biopsies. Thirteen antigliadin antibody-positive patients were antiendomysial antibody-negative; one antiendomysial antibody-negative patient had celiac disease. The prevalence of celiac disease was 2.6% among 234 patients.

CONCLUSIONS

Measurement of antigliadin antibodies in patients with diabetes mellitus type 1 helped in the selection of patients to undergo jejunal biopsy. Antiendomysial antibodies were highly specific and moderately sensitive in predicting celiac disease. The prevalence of celiac disease was higher in diabetics than in the general population, suggesting the need for regular screening assessment of diabetic children.

What are the sensitivity and specificity of serologic tests for celiac disease? Do sensitivity and specificity vary in different populations?

A number of serologic tests are available commercially for identifying individuals who require an intestinal biopsy examination to diagnose celiac disease (CD). The aim of this study was to determine which test, or combination of tests, was most sensitive and specific for this purpose. We performed a literature review of studies that determined the sensitivity and specificity of serologic tests for CD. Studies that compared biopsy examination-confirmed cases of CD with controls with normal intestinal histology were selected for analysis. Sensitivities and specificities for the antigliadin tests were highly variable. Immunoglobulin (Ig)G-based antigliadin (AGA) tests generally were poor in both parameters whereas the IgA-based test was poorly sensitive but more specific. The IgA endomysium (EMA-IgA) and tissue transglutaminase (TTG-IgA) tests were both highly sensitive and specific with values for both parameters exceeding 95% in most studies. There were no identifiable differences between adults and children with respect to these tests. There was no evidence that a combination of tests was better than a single test using either the EMA IgA or TTG IgA. Either the EMA-IgA or TTG-IgA test is most useful for identifying individuals with CD. The variability and generally lower accuracy associated with the AGA tests make them unsuitable for screening purposes. There is no advantage to using a panel of tests as opposed to a single test. Because these data were obtained largely from studies conducted in a research setting, it is possible the tests will be less accurate when used in the clinical setting.

The diagnostic accuracy of serologic tests for celiac disease: a systematic review

Clinicians are increasingly utilizing noninvasive serologic tests for the diagnosis and screening of celiac disease (CD). The aim of this study was to conduct a systematic review of the diagnostic performance of serologic tests for the diagnosis and screening of CD. Standard systematic review methodology was used. A literature search was conducted in MEDLINE (1966 to October 2003) and EMBASE (1974 to December 2003) databases. A weighted mean of the sensitivity and specificity along with 95% confidence intervals and summary receiver operating characteristic (ROC) curves were calculated. The pooled specificity of endomyseal antibody (EMA)-monkey esophagus (ME) or EMA-human umbilical cord (HU) was close to 100% in adults and children. The pooled specificity of transglutaminase antibody (tTG)-guinea pig (GP) and tTG-human recombinant (HR) were between 95% and 99%. IgA-EMA-ME demonstrated sensitivities of 96% and 97% in children and adults, respectively. EMA-HU demonstrated a similar sensitivity of 97% in children but 90% in adults. The pooled sensitivity of tTG-GP in adults and children was 90% and 93%, respectively. The sensitivity of tTG-HR was 98% and 96%, respectively. The performance of antigliadin antibody was inferior to that of EMA and tTG. EMA and tTG offer high sensitivity and specificity. The sensitivity of these tests appears to be lower than reported when milder histologic grades are used to define CD (below 90%). If true, the nearly perfect negative predictive value of these tests would drop. The positive predictive value of these tests is likely lower than reported when the tests are applied in low-prevalence populations.

Antibody levels in adult patients with coeliac disease during gluten-free diet: a rapid initial decrease of clinical importance

OBJECTIVE

Analysis of antibodies against tissue transglutaminase (tTG) has been shown valuable in the diagnosis of coeliac disease (CD) but how quickly serum titres decrease after introduction of a gluten-free diet (GFD) is not known in adults. CD is a well-recognized disorder amongst the general population and many persons try a GFD for fairly vague symptoms before they seek medical advice. Therefore, it is important to determine the time that the serologic tests remain predictive of the disease after the introduction of a GFD.

METHODS

Sera were taken from 22 consecutively biopsy-proven adult patients with CD in connection with the diagnostic biopsy. The patients were followed for 1 year and sera were taken after 1, 3, 6 and 12 months after start of a GFD. Sera were stored at -20 degrees C and analysed for IgA antibodies against gliadin, endomysium and two different commercial tTG assays based on recombinant human tTG (tTGrh) and guinea-pig liver (tTGgp).

RESULTS

Twenty patients could be followed during GFD and all antibody titres fell sharply within 1 month after introduction of a GFD and continued to decline during the survey interval. Thirty days after beginning the diet only 58, 84, 74 and 53% of all patients had positive antibody levels of tTGrh, tTGgp, EmA and AGA respectively.

CONCLUSIONS

As the antibodies used to confirm the diagnosis of CD fall rapidly and continue to decline following the introduction of a GFD, it is important that health care providers carefully inquire about the possibility of self-prescribed diets before patients sought medical attention.

Prevalence of celiac disease in Brazilian children of short stature

The aim of the present study was to determine the prevalence of celiac disease in children of short stature and to assess whether some of the routine laboratory examinations performed to determine the cause of short stature could suggest the presence of celiac disease. A total of 106 children of short stature and no gastrointestinal symptoms were studied. An extensive endocrine work-up had been negative for all of them and an additional investigation was performed by measuring the concentration of antiendomysial antibody. Patients who were positive for antiendomysial antibody (> or =1:10) or who exhibited IgA deficiency (less than 5 mg/dl) were referred for an endoscopic intestinal biopsy. We detected a pathological titer of antiendomysial IgA in six of these patients. Five of them showed histological abnormalities compatible with celiac disease and one had normal histology and was considered to have potential celiac disease. The prevalence of celiac disease in the population studied was 4.7% (with another 0.9% of the subjects being considered to have potential celiac disease). The children with celiac disease did not differ in any of the parameters tested when compared to those without celiac disease, though they showed an improvement in growth velocity after treatment with a gluten-free diet. We conclude that it is important to test all children with short stature for celiac disease by measuring antiendomysial IgA.

A comparison of antibodies to tissue transglutaminase with conventional serological tests in the diagnosis of coeliac disease

BACKGROUND

Tissue transglutaminase is now recognized as the autoantigen for antiendomysial antibodies. Antibodies to tissue transglutaminase have been proposed as a valuable test for coeliac disease.

OBJECTIVE

To determine the value of antibodies to tissue transglutaminase in the diagnosis of coeliac disease in our outpatient population.

METHODS

Patients who underwent serological tests for coeliac disease during the first 18 months of the tissue transglutaminase antibody assay were retrospectively identified from the regional serology laboratory database. Patients' symptoms were noted, along with serological results and duodenal histology in those patients who underwent duodenal biopsy. RESULTS In total, 586 patients were identified as having been serologically tested for coeliac disease, of whom 92 patients (33 men; mean age 51.7 years) had been followed up with duodenal biopsies. Of these 92 patients, 29 (31%; 14 men; mean age 52.5 years) had histological features of coeliac disease. The 63 patients with normal histology (19 men; mean age 51.8 years) acted as controls. Weight loss was more frequent in coeliac disease patients compared to controls (7 vs 5; P = 0.04) whereas the frequency of anaemia (P = 0.85) and diarrhoea (P = 0.74) did not differ significantly between the two groups. The sensitivity and specificity of tissue transglutaminase antibodies (86%; 84%) were compared to those for antiendomysial antibodies (90%; 98%) and antigliadin antibodies (76%; 79%).

CONCLUSIONS

The diagnostic value of tissue transglutaminase antibodies was intermediate between that of antiendomysial antibodies and antigliadin antibodies. However, duodenal biopsy remains the gold standard diagnostic test for coeliac disease.

Is the risk of adult coeliac disease causally related to cigarette exposure?

OBJECTIVE

Previous studies have shown an association between cigarette smoking and coeliac disease, but it has yet to be established whether this relationship is causal. The aim of this study was to assess causality using the Bradford Hill criteria.

METHODS

A matched case-control study using a questionnaire to establish a detailed smoking history for 138 incident cases of adult coeliac disease and 276 age-matched and sex-matched controls. Subjects were categorized according to their active cigarette exposure prior to diagnosis of the matched case, and odds ratios and tests for linear trends were calculated.

RESULTS

At the time of diagnosis, 10% of cases and 30% of controls were current smokers (odds ratio, 0.21 and 95% confidence interval, 0.11-0.40 for coeliac disease in current smokers versus never smokers). A biological gradient was demonstrated for total, recent and current cigarette exposure. The greatest risk reduction related to current exposure (odds ratio, 0.15, and 95% confidence interval, 0.06-0.37 for coeliac disease in current heavy smokers versus never smokers).

CONCLUSIONS

This study strengthens the case for a causal relationship between smoking and coeliac disease by demonstrating a strong, temporally appropriate and dose-dependent effect, thus meeting the Bradford Hill criteria. This suggests that cigarette smoking truly protects against the development of adult coeliac disease.

A prospective study of the prevalence of undiagnosed coeliac disease in laboratory defined iron and folate deficiency

AIMS

To determine the prevalence of coeliac disease in a group of patients in the community who have been shown in the laboratory to have iron and/or folate deficiency. To assess the cost efficiency of this laboratory based case finding strategy.

METHODS

The study was undertaken in a large general hospital in the UK serving a population of 300 000. Three hundred and thirty three eligible patients with iron and/or folate deficiency were identified and contacted over an 18 month period. Case finding was by testing for coeliac disease using serological methods and subsequent histological confirmation.

RESULTS

Of the 333 eligible and contactable patients with iron and/or folate deficiency, 258 (77%) consented to coeliac disease antibody testing. Twenty eight patients (10.9%) were positive for coeliac disease antibodies. Of these, 24 patients proceeded to endoscopy and biopsy, resulting in 12 cases of histologically confirmed coeliac disease (4.7% (95% confidence interval, 2.1% to 6.8%) of patients tested for coeliac disease antibodies).

CONCLUSIONS

This laboratory based methodology detected a considerable number of new coeliac disease cases in the community. Many of these patients did not present with clinical findings suggestive of malabsorption and might not otherwise have been diagnosed. Laboratory based methodologies should be considered in conjunction with other strategies for the early identification and treatment of coeliac disease.

A controlled, prospective screening study of celiac disease presenting as iron deficiency anemia

BACKGROUND

anemia is the most frequent presenting feature of celiac disease in adults using endomysial antibody (EmA) screening. Endomysial antibody screening of anemia may allow detection of celiac disease at an earlier stage of investigation and after a shorter duration of symptoms. The characteristics of celiac patients identified by screening require further study.

GOALS

a goal of this study was to evaluate the prevalence of celiac disease in adult patients with iron deficiency anemia compared with a nonanemic control population using immunoglobulin A (IgA) EmA screening. We also studied the positive predictive value (PPV) of the EmA assay and correlated the severity of histologic abnormalities in distal duodenal biopsy samples with EmA and tissue transglutaminase (tTG) antibody titer.

STUDY

four hundred eighty-four patients with microcytic, hypochromic anemia underwent IgA EmA assay. Four hundred ninety-eight nonanemic age- and sex-matched patients from the same source comprised the control group. Patients with positive serology results were invited for endoscopic duodenal biopsies.

RESULTS

one in 44 anemic patients was diagnosed with histologically confirmed celiac disease compared with one in 498 nonanemic patients ( < 0.01). Fifty percent of women were premenopausal, and 25% of patients were older than 65 years. The PPV for EmA assay varied between 73% and 93% for anemic patients and improved at higher antibody titer, with all false-positive results occurring at the lowest titers.

CONCLUSIONS

screening for celiac disease using IgA EmA assay is effective in anemic patients, including premenopausal women and patients older than 65 years, and it can be recommended in clinical practice.

Endocrinological disorders and celiac disease

Celiac disease is a permanent intolerance to dietary gluten. Its well known features are abdominal symptoms, malabsorption of nutrients, and small-bowel mucosal inflammation with villous atrophy, which recover on a gluten-free diet. Diagnosis is challenging in that patients often suffer from subtle, if any, symptoms. The risk of clinically silent celiac disease is increased in various autoimmune conditions. The endocrinologist, especially, should maintain high suspicion and alertness to celiac disease, which is to be found in 2-5% of patients with insulin-dependent diabetes mellitus or autoimmune thyroid disease. Patients with multiple endocrine disorders, Addison's disease, alopecia, or hypophysitis may also have concomitant celiac disease. Similar heredity and proneness to autoimmune conditions are considered to be explanations for these associations. A gluten-free diet is essential to prevent celiac complications such as anemia, osteoporosis, and infertility. The diet may also be beneficial in the treatment of the underlying endocrinological disease; prolonged gluten exposure may even contribute to the development of autoimmune diseases. The diagnosis of celiac disease requires endoscopic biopsy, but serological screening with antiendomysial and antitissue transglutaminase antibody assays is an easy method for preliminary case finding. Celiac disease will be increasingly detected provided the close association with autoimmune endocrinological diseases is recognized.

IgA-class transglutaminase antibodies in evaluating the efficacy of gluten-free diet in coeliac disease

OBJECTIVE

Serum IgA-class tissue transglutaminase antibody has proved effective in screening for coeliac disease. The response to a gluten-free diet has been assessed on the basis of small-intestinal morphology. We investigated whether the tissue transglutaminase antibody test could substitute biopsy in this respect, and whether the test is better than the endomysial antibody test in follow-up.

DESIGN

Controlled cross sectional, and follow-up study.

METHODS

Serum IgA-class tissue transglutaminase antibodies and endomysial antibodies were determined in 87 coeliac adults on a gluten-free diet. All underwent small bowel biopsy, and the mucosal morphology was interpreted along with Marsh's grading 0-3. In 30 patients histological and serological data could be analysed before and after adopting the diet; Marsh 3 was considered inadequate mucosal recovery during the diet.

RESULTS

Of the 87 coeliac patients 27 showed Marsh 3 villous atrophy on gluten-free diet; of these 27, tissue transglutaminase antibody was within normal limits in 16 (59%) and endomysial antibody in 20 (74%). Two (7%) out of 29 with normal mucosa (Marsh 0) had positive tissue transglutaminase antibodies. Six (55%) out of 11 admitting regular dietary lapses remained tissue transglutaminase antibody negative. In the follow-up, serum IgA-class tissue transglutaminase antibody was initially positive in 28 (93%) out of 30 untreated patients; even a significant decrease in tissue transglutaminase antibody did not guarantee mucosal recovery.

CONCLUSIONS

A substantial number of coeliac patients with negative tissue transglutaminase or endomysial antibodies may still have manifest mucosal villous atrophy. Small bowel biopsy is therefore still necessary to ensure that the gluten-free diet is adequate.

Diagnostic approach to a patient with suspected celiac disease: a cost analysis

Serological testing is an important tool in the diagnostic work-up of suspected celiac disease. Our aim was to apply a decision analysis model to compare the costs of serological testing versus small bowel biopsy in the diagnostic work-up of celiac disease. A cost-minimization approach was employed. A decision analysis model with three diagnostic arms was designed using Data Version 3.5: anti-gliadin antibody versus endomysial antibody versus small bowel biopsy. Response to gluten-free diet was considered diagnostic of celiac disease; lack of response prompted a small bowel biopsy to definitively exclude celiac disease. Baseline probabilities were varied using sensitivity analysis. Sensitivity analysis revealed that the endomysial antibody strategy was least costly, provided the prevalence of celiac disease was less than 42%; above this anti-gliadin antibody became the most economical option. In conclusion, initial screening with endomysial antibody is the least costly strategy for diagnosing celiac disease in a low risk population. Antigliadin antibody becomes the cheaper strategy for higher risk populations.

Do you still need a biopsy to diagnose celiac disease?

Celiac disease is a common and permanent condition caused by an abnormal immune response to ingested gluten in genetically susceptible individuals. Its proper diagnosis is very important even in patients presenting with mild symptoms because severe and debilitating complications may occur in celiac patients not following a strict gluten-free diet. In the past several years, important progress has been made not only in our understanding of the pathogenesis of this condition but also in the availability of tools to screen it. Antigliadin antibodies, once largely used for this purpose, have been basically replaced by the more costly but far more accurate antiendomysium antibodies. More recently, the enzyme-linked immunosorbent assay (ELISA), which measures the antibodies directed against the autoantigen responsible for the disease (tissue transglutaminase), has also been developed and tested as a screening tool. Currently, however, the poor positive predictive value of this test does not allow practitioners to diagnose celiac disease without the duodenal biopsy showing the typical morphologic changes.

Adult endomysial antibody-negative coeliac disease and cigarette smoking

OBJECTIVE

To determine the relative incidence and characteristics of endomysial antibody (EMA)-negative coeliac disease in adults.

DESIGN

Retrospective analysis of prospectively collected data on adults with newly diagnosed coeliac disease, with determination of EMA status before gluten withdrawal.

SETTING

District general hospital (secondary care institution).

PARTICIPANTS

Sixty consecutive incident cases.

MAIN OUTCOME MEASURES

(i) Proportion of cases who were EMA-negative; (ii) comparison of clinical and laboratory variables at diagnosis for EMA-positive and EMA-negative subjects.

RESULTS

Fifteen subjects (25%, 95% CI 15-38%) were EMA negative, of whom only two were IgA deficient. There was clinical evidence in all 15 patients and histological evidence in 13 patients of a response to gluten withdrawal. No significant differences were found between EMA-positive and EMA-negative subjects with respect to histological features, age, gender, clinical manifestations, concurrent autoimmune disorders, family history of coeliac disease, or haemoglobin and albumin concentrations at diagnosis. However, EMA-negative status at diagnosis was associated strongly with current or recent cigarette smoking (OR 7.0, 95% CI 1.7-31.5, P= 0.003).

CONCLUSIONS

A substantial minority of patients with otherwise typical coeliac disease are EMA negative, and most of these are IgA replete. The value of EMA as a screening tool is therefore limited. EMA status in untreated coeliac disease correlates strongly with cigarette smoking history: this may be of pathogenic significance, given the previously demonstrated association between smoking and the risk of coeliac disease.

Celiac disease in older people

In recent years, there has been increasing recognition that the classical textbook presentation of celiac disease with a malabsorption syndrome and a flat jejunal mucosa is only part of a broad spectrum of clinical and histological features associated with gluten sensitivity. Diagnosis of this treatable condition is often delayed or missed because of a failure to appreciate that celiac disease can present at any age and that symptoms are often subtle and not clearly related to gastrointestinal disease. Nonspecific symptoms and nutritional deficiencies are especially common in older patients and may not always be investigated thoroughly. Use of serological screening tests has improved ease of detection of celiac disease in patients without classical symptoms.

Comparative evaluation of serologic tests for celiac disease: a European initiative toward standardization

BACKGROUND

Serologic methods have been used widely to test for celiac disease and have gained importance in diagnostic definition and in new epidemiologic findings. However, there is no standardization, and there are no reference protocols and materials.

METHODS

The European working group on Serological Screening for Celiac Disease has defined robust noncommercial test protocols for immunoglobulin (Ig)G and IgA gliadin antibodies and for IgA autoantibodies against endomysium and tissue transglutaminase. Standard curves were linear in the decisive range, and intra-assay variation coefficients were less than 5% to 10%. Calibration was performed with a group reference serum. Joint cutoff limits were used. Seven laboratories took part in the final collaborative study on 252 randomized sera classified by histology (103 pediatric and adult patients with active celiac disease, 89 disease control subjects, and 60 blood donors).

RESULTS

IgA autoantibodies against endomysium and tissue transglutaminase rendered superior sensitivity (90% and 93%, respectively) and specificity (99% and 95%, respectively) over IgA and IgG gliadin antibodies. Tissue transglutaminase antibody testing showed superior receiver operating characteristic performance compared with gliadin antibodies. The K values for interlaboratory reproducibility showed superiority for IgA endomysium (0.93) in comparison with tissue transglutaminase antibodies (0.83) and gliadin antibodies (0.82 for IgG, 0.62 for IgA).

CONCLUSIONS

Basic criteria of standardization and quality assessment must be fulfilled by any given test protocol proposed for serologic investigation of celiac disease. The working group has produced robust test protocols and reference materials available for standardization to further improve reliability of serologic testing for celiac disease.

Endomysial antibody in the diagnosis and management of coeliac disease

This review determines the significance, usefulness, and application of the endomysial antibody test for coeliac disease in clinical practice.

Cost-effective strategy for the serological investigation of coeliac disease

Increased numbers of requests for serological investigation of coeliac disease, and a local trend to request both anti-gliadin antibodies (AGA) and anti-endomysium antibodies (AEA) simultaneously, resulted in cost pressures that prompted a review of our practice. Serology results from all patients (771 children, 511 adults) investigated for coeliac disease over a 3-year period were compared with small intestine histology where available. IgG AGA and IgA AGA were measured by enzyme-linked immunosorbent assay (in-house), IgA AEA by immunofluorescence (send-away contract). Overall diagnostic performance was as follows: AGA sensitivity 84%, specificity 88%, positive predictive value (PPV) 24%, negative predictive value (NPV) 99%; AEA sensitivity 88%, specificity 97%, PPV 65%, NPV 99%. Results showed AGA, with its high NPV, to be a suitable first-line test to exclude coeliac disease. The high specificity of AEA makes it a suitable confirmatory test when AGA is positive. Introduction of this step-wise approach to coeliac disease investigation resulted in cost savings of at least Pound Sterling 5000 per year without detriment to the clinical service.

Refractory celiac disease

Celiac disease is a gluten-sensitive enteropathy, characterized by villous atrophy, which is reversed by gluten withdrawal. A minority of patients with celiac-like enteropathy are resistant to gluten-free diet, so-called refractory sprue, or unclassified sprue. Refractory sprue is a diagnosis of exclusion; all other causes of a celiac-like enteropathy must be eliminated before a diagnosis of refractory sprue can be made. Recent evidence suggests that refractory sprue comprises a heterogenous group of patients with diverse underlying causes. A small proportion of these patients seem to have an adult form of autoimmune enteropathy, characterized by the presence of antienterocyte antibodies. However, a larger group of patients with refractory sprue now seem to have a cryptic intestinal T-cell lymphoma, characterized by the presence of phenotypically abnormal, monoclonal intraepithelial lymphocytes, despite benign cytology. Current therapeutic options include nutritional support and immunosuppressive therapy, but response is variable. The prognosis of refractory sprue may be poor; patients may die of severe malabsorption, or through synchronous or metachronous development of an enteropathy-associated T-cell lymphoma. Based on this recent evidence, patients with refractory sprue should be screened for antienterocyte antibodies and have T-cell receptor and monoclonal antibody studies performed; this could facilitate identification of cases of adult-onset autoimmune enteropathy and those of cryptic T-cell lymphoma. Moreover, early recognition of the malignant nature of the intestinal infiltrate in some cases of refractory sprue could permit the development of novel chemotherapeutic regimens for this condition.

Serologic testing for celiac disease in the United States: results of a multilaboratory comparison study

The aim of this study was to compare the efficiencies of six reference laboratories for serologic testing for celiac disease. Serum from 20 patients with untreated celiac disease and from 20 controls was thawed, divided, and distributed to each participating laboratory, which performed endomysial antibody tests. Five laboratories also performed antigliadin antibody tests. Sensitivity for endomysial antibody immunoglobulin A (IgA) varied from 57 to 90%. In all laboratories, the specificity for celiac disease was 100%. The sensitivity and specificity for both IgA and IgG antigliadin antibody varied significantly. When results from all three tests were combined in each laboratory, sensitivity was 90 to 100%. The specificity for endomysial antibody was 100% in the laboratories. Sensitivity was less than reported previously. Standardization of these tests is needed in the United States.

Endomysium antibodies are superior to gliadin antibodies in screening for coeliac disease in patients presenting supposed functional gastrointestinal symptoms

OBJECTIVE

To study the accuracy of IgA- and IgC-gluten antibodies and endomysium antibodies as screening tools for endoscopy with small bowel biopsy for histologic diagnosing of coeliac disease.

DESIGN

Comparing serology with histologic examination--the "gold standard" for diagnosing coeliac disease.

SETTINGS

1. The municipality of Osthammar, Sweden. 2. The catchment area of the University Hospital, Uppsala, Sweden.

PATIENTS

1. A random subsample (50 with dyspepsia, 50 with irritable bowel syndrome and 50 symptomless) of a representative sample from an adult Swedish general population (20-80 years; n = 1260). 2. All patients with a diagnosis of coeliac disease admitted to the University Hospital in Uppsala, Sweden during the course of 10 months.

MAIN OUTCOME MEASURES

The accuracy of IgA- and IgG-gluten antibodies and endomysium antibodies.

RESULTS

There were no significant correlations between IgA-gluten antibodies and IgG-gluten antibodies, on the one hand, and symptoms or symptom severity, on the other. Using duodenal biopsy results as the gold standard, IgA-gluten antibodies had a low specificity and IgG-gluten antibodies a low sensitivity, whereas endomysium antibodies had an excellent accuracy.

CONCLUSION

Endomysium antibodies seem to be the screening test of choice. The load of diagnostic upper endoscopies would be considerably decreased compared to using gluten antibodies.

Lack of cellular and humoral immunological responses to oats in adults with coeliac disease

OBJECTIVE

Recent research suggests that oats do not harm intestinal villi in adults with coeliac disease. As the immunological effects of oats have not been examined in detail, it was decided to compare the immunological responses of a gluten free diet including oats with those of a conventional gluten free diet.

DESIGN

A randomised controlled intervention study over 6-12 months.

SUBJECTS

Forty adults with newly diagnosed coeliac disease and 52 with coeliac disease in remission were examined.

INTERVENTION

The effects of a gluten free diet including oats and a conventional gluten free diet were compared.

MAIN OUTCOME MEASURES

Serum levels of gliadin and reticulin antibodies as well as numbers of intraepithelial lymphocytes (IELs) in intestinal mucosa were examined before and after the intervention.

RESULTS

The rate of disappearance of gliadin and reticulin antibodies did not differ between the diet groups in patients with newly diagnosed coeliac disease. Oats also had no effect on gliadin or reticulin antibody levels in the patients with remission. The number of IELs decreased similarly regardless of the diet of newly diagnosed patients, and no increase in the number of IELs was found in the patients in remission with or without oats.

CONCLUSIONS

These results strengthen the view that adult patients with coeliac disease can consume moderate amounts of oats without adverse immunological effects.

Antibodies to gliadin, endomysium, and tissue transglutaminase for the diagnosis of celiac disease

BACKGROUND

Tissue transglutaminase has recently been identified as the main autoantigen recognized by antiendomysial antibodies in celiac disease. Serum immunoglobulin (Ig)A antibodies to tissue transglutaminase (tTG-ab) determined by an enzyme-linked immunosorbent assay (ELISA) technique have been reported to correlate closely with IgA antiendomysial antibodies (EMA). The purpose of this study was to assess the sensitivity, specificity, and predictive value of tTG-ab measured by a commercially available ELISA technique, compared with those of EMA and IgA antigliadin antibodies (AGA) for the diagnosis of celiac disease.

METHODS

Twenty-seven serum samples were obtained from patients with untreated celiac disease, 37 from patients who had had gluten withdrawn from their diets for varying time spans, and 34 from control subjects without celiac disease. All were younger than 14 years. Presence of tTG-ab and AGA was determined by ELISA and of EMA by indirect immunofluorescence.

RESULTS

Twenty-six of 27 serum samples obtained from patients at the time of diagnosis of celiac disease were AGA positive. All 27 (concordance rate 100%) were positive for EMA and tTG-ab. Of the 34 control subjects, 1 was for AGA and 2 for tTG-ab. All 34 were negative for EMA. Sensitivity, specificity, positive predictive value, and negative predictive value within this group were, for tTG-ab: 100%, 94%, 93%, and 100%, respectively; for EMA: all four indexes were 100%; and for AGA: 96%, 97%, 96%, and 97%, respectively. Of the 37 with treated celiac disease, 2 were AGA positive, 9 were EMA positive, and 6 were tTG-ab positive. The concordance rate between EMA and tTG-ab was 100% in the group with untreated celiac disease, 94% in the control subjects, and 76% in the group with treated celiac disease.

CONCLUSIONS

Immunoglobulin A antibodies to tissue transglutaminase are new, highly sensitive, and specific markers of celiac disease. They can be determined easily by an accurate, comparatively cheap technique and thereby may advantageously replace the EMA marker traditionally used.

Application of red cell distribution width to screening for coeliac disease in insulin-dependent diabetes mellitus

Coeliac disease has been reported to occur in 2-5 per cent of insulin-dependent diabetic patients (IDDM). Suitable non-invasive screening tests would allow identification of these patients. The aim of this study was to determine the value of the red cell distribution width (RDW) in detecting unrecognised coeliac disease in insulin-dependent diabetic patients (IDDM). All patients (n = 208) attending the Diabetic out-patient clinics at 2 adjacent centres who had a full blood picture and RDW carried out in the past 18 months were included. IDDM patients with an elevated RDW were identified and their charts were reviewed to determine if they had symptoms or laboratory abnormalities compatible with coeliac disease. They were invited to attend for serological screening. Ninety-five of 208 patients had an elevated RDW of whom 66 had non-insulin dependent diabetes mellitus and 29 had IDDM. Two of the 29 IDDM patients had died in the interim period. Six of the remaining 27 IDDM patients had previously been tested for serological markers associated with coeliac disease, of whom 1 had a positive antigliadin antibody titre (IgA-AGA 199 EU) and normal duodenal biopsy. Eighteen of the remaining 21 patients with IDDM consented to serological testing of whom only 1 had a positive titre of antiendomysial antibody (IgA-EMA) and villous atrophy. Although the RDW is known from previous studies to be a sensitive predictor for coeliac disease, this study has demonstrated its poor specificity in predicting IDDM patients who may have coeliac disease. The RDW is not recommended as a screening test for coeliac disease in patients with IDDM.

Coeliac disease in primary care: case finding study

OBJECTIVES

To provide evidence of underdiagnosis of coeliac disease and to describe the main presenting symptoms of coeliac disease in primary care.

DESIGN

Case finding in a primary care setting by testing for coeliac disease by using the endomysial antibody test.

SETTING

Nine surgeries in and around a market town in central England, serving a population of 70 000.

PARTICIPANTS

First 1000 patients screened from October 1996 to October 1997.

OUTCOME MEASURES

Determination of endomysial antibody titre of patients fulfilling the study criteria, followed by small intestine biopsy of those with positive results.

RESULTS

The 30 patients (out of 1000 samples) with positive results on the endomysial antibody test all had histological confirmation on small intestine biopsy. The commonest mode of presentation (15/30) was anaemia of varying severity. Most patients (25/30) presented with non-gastrointestinal symptoms. Specificity of the endomysial antibody test was 30/30.

CONCLUSIONS

Underdiagnosis and misdiagnosis of coeliac disease are common in general practice and often result in protracted and unnecessary morbidity. Serological screening in primary care will uncover a large proportion of patients with this condition and should be made widely available and publicised. Coeliac disease should be considered in patients who have anaemia or are tired all the time, especially when there is a family history of the disease.

Identifying immunoglobulin-A--deficient children and adults does not necessarily help the serologic diagnosis of coeliac disease

BACKGROUND

Immunoglobulin A deficiency is more common in patients with coeliac disease and also in patients with other gastrointestinal diseases than in normal people. There is a concern, therefore, that routine serum immunoglobulin (Ig) A testing of all cases of suspected coeliac disease may lead to unnecessary biopsy.

METHODS

Four hundred eighty-two routine consecutive samples from cases of suspected coeliac disease or malabsorption (109 children) were tested for IgA anti-endomysium and total IgA. Four hundred twenty-four sera samples also had IgG antigliadin checked for high-titre antibody. Archived adult sera from 31 patients with coeliac disease and 52 disease control subjects were included in the study.

RESULTS

Seven routine cases with serum IgA less than 15% of the mean normal for age and four cases with undetectable IgA were identified. Four patients, including three of four with clear deficiency, underwent small bowel biopsy, and all four had normal histologic findings and normal intraepithelial lymphocyte counts. Only one of the seven had high-titre IgG antigliadin antibody but that patient had normal histologic findings. One (3%) of 31 adults with established coeliac disease and 1 (2%) of 52 control subjects were IgA deficient.

CONCLUSIONS

Of patients with IgA deficiency, only those with both IgA deficiency and high-titre IgG antigliadin antibody should be routinely considered for biopsy.

Small-bowel mucosal inflammation in reticulin or gliadin antibody-positive patients without villous atrophy

BACKGROUND

We investigated whether individuals with positive coeliac disease antibodies but without small-bowel villous atrophy have mucosal inflammation implicating gluten-sensitivity.

METHODS

Small-bowel mucosal morphology; CD3+, alphabeta+, and gammadelta+ T-cell receptor-bearing intraepithelial lymphocytes; and mucosal HLA-DR expression were studied in 96 IgA-class antireticulin or antigliadin antibody-positive adults suspected of having coeliac disease and in 27 control subjects.

RESULTS

Villous atrophy compatible with coeliac disease was found in altogether 29 patients, in 18 of 21 (86%) patients with both antireticulin and antigliadin antibodies, in 9 of 15 (60%) patients with antireticulin antibodies only, and in 2 of 60 (3%) with antigliadin antibodies only. In 67 antibody-positive patients with normal villous architecture the densities of CD3+, alphabeta+, and gammadelta+ intraepithelial lymphocytes were significantly higher than in non-coeliac control subjects. Ten patients with initially increased densities of gammadelta+ T cells but normal villous structure underwent a follow-up biopsy after 4-18 months, which showed villous atrophy in five patients.

CONCLUSIONS

IgA-class antireticulin or antigliadin antibody-positive patients with normal small-bowel mucosal morphology frequently have immunohistochemical markers of coeliac disease latency. Together with our follow-up data this implies that they may be gluten-sensitive.

Further studies of anti-endomysium and anti-gliadin antibodies in patients with suspected celiac disease

BACKGROUND

The finding of characteristic small intestinal mucosal abnormalities on histologic examination of a biopsy specimen remains the first requirement for the diagnosis of celiac disease. A reliable and noninvasive test would be ideal for the patient's convenience and for reducing health-care costs. The sensitivity and specificity of anti-gliadin antibodies (AGA-immunoglobulin [Ig] G, AGA-IgA) have been variable; anti-endomysium IgA (EmA-IgA) is more helpful. In an earlier study conducted at the authors' institution, celiac disease was present in 19 patients examined from 1992 to 1995. Anti-endomysium titers were higher than normal in all 19 patients (100%). Total villous atrophy was seen in 14 of 17 biopsy specimens (82%) and subtotal atrophy in 3 (18%). The purpose of the current study was to evaluate further the accuracy of EmA-IgA in diagnosing celiac disease.

METHODS

One hundred seven patients were screened for celiac disease between March 1996 and July 1997. The level of EmA-IgA was measured in all patients, and AGA-IgG and AGA-IgA were measured in 104 patients. Forty-six patients underwent endoscopic biopsy of the small bowel, with measurement of disaccharidase enzymes in 45 patients.

RESULTS

Five of 46 patients had celiac disease (three boys and two girls; mean age, 5.3 years; 2-9.5 years); one also had cystic fibrosis and another had insulin-dependent diabetes mellitus. All five had marked to complete villous atrophy with crypt hyperplasia and increased serum EmA-IgA (100% sensitivity). None of the remaining patients had increased EmA-IgA (100% specificity). Serum levels of AGA-IgG and AGA-IgA were increased in all four celiac disease patients (100% sensitivity), but they were also high in patients without celiac disease (38% and 92% specificity, respectively), which compromises their diagnostic value. None of the patients confirmed to have celiac disease had IgA deficiency. Abnormal disaccharidase enzyme activities were documented in all five celiac disease patients: severe generalized deficiency (n = 2), moderately severe generalized deficiency (n = 2), and alactasia with moderate deficiency of the alpha-glucosidases (n = 1).

CONCLUSIONS

This study confirmed the reliability and accuracy of EmA-IgA in the diagnosis of celiac disease. Small bowel biopsy may be unnecessary in EmA-positive patients in whom celiac disease is suspected.

New clinical issues in celiac disease

Celiac disease is a chronic disorder of gluten sensitivity associated with a spectrum of mucosal lesions termed preinfiltrative, infiltrative, hyperplastic, destructive, and atrophic. The symptoms are not related to the degree of mucosal pathology but to the extent of the mucosal lesion. Neoplasms constitute the major complication of celiac disease, and EATCL is the most common neoplasm in this category. There is evidence that a strict gluten-free diet is protective against the complications of celiac disease; hence it is important that even the subclinical forms be diagnosed early. Small bowel biopsy remains the gold standard for diagnosis of celiac disease; however, antibody tests are a useful adjunct in deciding whom to biopsy and for screening groups at high risk before initiating a lifelong gluten-free diet.

Identification of coeliac disease in primary care

BACKGROUND

Coeliac disease is common yet often undiagnosed because symptoms may be trivial, non-specific, or non-gastrointestinal, or because of lack of clinician awareness. Serum IgA-class endomysial antibodies (EmA) have high specificity for coeliac disease and may facilitate case-finding by clinicians other than gastroenterologists. We assessed the appropriateness and diagnostic yield of of requests for EmA by primary care general practitioners in a defined geographic area of Northern Ireland.

METHODS

We identified patients who had EmA examination requests by their general practitioners during 1994-1996. Individual patient questionnaires were posted to the general practitioners concerned, seeking information on indications for testing, management after the result, and final diagnosis. We compared new patient diagnosis rates in two catchment areas, one served by a large district general hospital with, and the other by smaller hospitals without, a medical gastroenterology facility.

RESULTS

A total of 239 patients had coeliac profile testing by 69 of 177 general practitioners in the area. Data were available for 181 patients not previously known to have coeliac disease, of whom 20 (11%) had EmA. All EmA-positive patients were referred to hospital, where 19 underwent small-bowel biopsy, which confirmed coeliac disease in all 19. Only 7 (35%) of the 20 had diarrhoea, and there was no significant difference in EmA prevalence among patients tested with and without diarrhoea. Although the mean number of new patients (per 100,000 population annually) diagnosed by biopsy was 11 at the large hospital compared with 5 elsewhere, the numbers identified by EmA in general practice for the 2 catchment areas were similar (2 and 3, respectively).

CONCLUSION

General practitioners have an important role in the identification of patients with coeliac disease, particularly where there is no local medical gastroenterology facility, and this is facilitated by EmA testing.

Dietary intake, smoking, and transient anti-gliadin antibodies

BACKGROUND

The detection of IgA anti-gliadin antibodies in adults can either be helpful in the diagnosis of coeliac disease, be persistent in subjects with normal jejunal mucosa, or occur transiently. We decided to investigate the effects of smoking, alcohol consumption, and dietary intake on the development of IgA anti-gliadin antibodies.

METHODS

Serum samples from subjects enrolled from a large Northern Ireland population sample (MONICA survey) were screened for IgA anti-endomysium and IgA anti-gliadin antibodies. All subjects with positive antibodies were invited for clinical assessment 3-4 years after the initial screening sample. During this follow-up a repeat serum sample was obtained and a jejunal biopsy performed. At enrollment in the MONICA survey, lifestyle information including smoking, alcohol consumption, and dietary intake was obtained.

RESULTS

At follow-up 13 subjects had persistent positive serology and villous atrophy, and 9 had persistent positive serology but normal jejunal histology; in 29 the serology had returned to normal, and the jejunal histology was normal There was no difference in smoking, alcohol consumption, or dietary intake between subjects with and without coeliac disease. Subjects with transient serology findings ate significantly more soda bread than the other groups (at the time of initial screening). Analysis of gliadin content of soda bread and plain white bread showed a significantly higher amount of gliadin present in soda bread.

CONCLUSIONS

Subjects with transient IgA anti-gliadin antibodies eat significantly more soda bread. The gliadin content of Irish soda bread contained a greater amount of gliadin than white bread. Eating breads with high available gliadin content may cause the appearance of anti-gliadin antibody.

Effectiveness of antigliadin antibodies as a screening test for celiac disease in children

OBJECTIVE

To test the effectiveness of serologic antigliadin antibody (AGA) testing in predicting celiac disease in children.

DESIGN

Prospective clinical assessment.

SETTING

Hôpital Sainte-Justine, montreal.

PATIENTS

A total of 176 children with possible celiac disease who were referred for duodenal biopsy between January 1992 and June 1995.

OUTCOME MEASURES

IgA and IgG AGA titres, as determined by enzyme-linked immunosorbent assay (ELISA); duodenal biopsy; clinical outcome on a gluten-free diet.

RESULTS

Of the 176 children 30 were found to have celiac disease according to the criteria of the European Society of Pediatric Gastroenterology and Nutrition (ESPGAN). The sensitivity and specificity of the IgA AGA titre, as well as its positive and negative predictive values, were 80%, 92%, 67% and 96% respectively; the corresponding values for the IgG AGA titre were 83%, 79%, 45% and 96%. The respective values for IgA and IgG AGA titres combined were 93%, 71%, 43% and 98%. Only 2 of the 30 patients with celiac disease had false-negative results for both IgA and IgG AGA titres. The IgA and IgG AGA titres decreased significantly (p < 0.005) in all 11 patients after being on a gluten-free diet for at least 10 months and reached normal values in 8.

CONCLUSION

AGA screening for celiac disease permits better selection of patients for duodenal biopsy and adds specificity to the histologic diagnosis. Such screening cannot replace intestinal biopsy, which remains the gold standard for diagnosis.

Prospective significance of antiendomysium antibody positivity in subsequently verified celiac disease

BACKGROUND

In order to assess their long-term predictability for the diagnosis of celiac disease, antiendomysium antibody results were compared with the outcome of the Interlaken diagnostic process.

METHODS

Prospective gluten challenge was performed in 153 children with previously diagnosed flat small-intestine mucosa. In 90 patients (Group A), endomysium antibodies were initially positive, in seven (Group B) they were negative, and 56 patients (Group C) had no initial serological results. In IgA-deficient persons, IgG antibodies were also assayed, both by the immunofluorescent method.

RESULTS

Histological relapse rates were 100% (90/90), 14.3% (1/7), and 76.8% (43/56), p < 0.001, in Groups A, B, and C, respectively. Each patient with relapse also exhibited endomysium antibody positivity during the challenge. Patients in whom celiac disease could be finally ruled out remained consistently endomysium-antibody negative. The celiac disease patient in Group B had severe secondary immunoglobulin deficiency at entry, which explained the initial negativity. Diagnosis based on antiendomysium antibody positivity and flat mucosa gave a higher applicability (92.8 vs. 50.3%) and reliability (relapse rate 100 vs. 89.6%) than the 1990 European Society of Paediatric Gastroenterology and Nutrition (ESPGAN) criteria among these patients.

CONCLUSIONS

Endomysium antibody positivity at presentation has been found to be as useful as gluten challenge in the diagnosis of celiac disease, even in patients under the age of 2 years. Challenge is still advisable in patients with a flat small intestinal mucosa when antiendomysium antibody results are negative or have not been done, as among these patients significantly lower relapse rates were found.

High prevalence of celiac sprue among patients with primary biliary cirrhosis

Although coexisting primary biliary cirrhosis (PBC) and celiac sprue have been described, celiac sprue is sufficiently common in western Europe for chance to explain isolated cases. We screened our patients with PBC for celiac sprue using serum immunoglobulin A endomysial antibody (EmA), with confirmation by duodenal biopsy in EmA-positive patients. Of 57 patients, 6 (11%) had EmA. Four agreed to have a biopsy taken, and all had villous atrophy, yielding a minimum prevalence of 1:14 (7%). Apart from anemia in one patient, none of the four had symptoms or routine laboratory abnormalities suggestive of celiac sprue. None had improvement in liver biochemical tests after 12 to 24 months on gluten-free diets despite the disappearance of EmA. Celiac sprue is common among patients with PBC and they should be routinely screened for this condition. Symptoms wrongly attributed to PBC may respond to gluten exclusion, and both conditions are potent risk factors for osteoporosis.