Systematic Literature Review of the Economic Burden of Celiac Disease

Celiac disease: Guideline update overview

ABSTRACT

The American College of Gastroenterology revised its recommendations for diagnosing and managing celiac disease in its updated 2023 clinical guideline. Celiac disease is an autoimmune disorder causing malabsorption following exposure to gluten. A wide range of both gastrointestinal and nongastrointestinal signs and symptoms can occur. This article provides an overview of the diagnosis and management of celiac disease, aiding the NP in developing a greater awareness of the condition both to diagnose it and to refer patients as needed to gastroenterology for evaluation.

"Per ELISA": Time to adopt anti-transglutaminase/deamidated gliadin peptide diagnostic combination in coeliac disease of adults?

BACKGROUND

Anti-endomysial antibodies (EMA) and anti-tissue transglutaminases (a-tTg) play a pivotal role in coeliac disease (CD) diagnosis. Deamidated anti-gliadin peptides (DGP) were added to the CD diagnostic workup.

AIMS

We aimed to compare the diagnostic accuracies of ELISA-based (a-tTg/DGP) and immunofluorescence-ELISA-based strategies (EMA/a-tTg) for CD diagnosis.

METHODS

From November 2020 to November 2022, we undertook an observational prospective study including consecutive adult patients with suspected CD. All subjects were tested for EMA, a-tTg and DGP IgA. An ROC curve was plotted to establish the best specificity cut-off of a-tTg and DGP levels, which would predict the presence of Marsh≥2 and Marsh=3. The diagnostic accuracies of a-tTg/DG and EMA/a-tTg were compared.

RESULTS

The study included 275 CD patients. Histology showed Marsh=1 in 9.9%, Marsh=2 in 4.5%, and Marsh=3 in 85.6.%. The best cut-off value of a-tTg for predicting Marsh≥2 was 42 U/mL, while the best cut-off for predicting atrophy was 68.4 U/mL. The best cut-off value of DGP for predicting Marsh≥2 was 56 U/mL, while the best cut-off for predicting atrophy was 78 U/mL. A-tTg/EMA showed 97% sensitivity and 100% specificity, whereas a-tTg/DGP showed 94% sensitivity and 100% specificity.

CONCLUSION

A-tTg/DGP is accurate for CD diagnosis and could reduce costs and operator-dependency of EMA. DGP, together with a-tTg, could replace EMA in CD diagnosis.

The Economic Iceberg of Celiac Disease: More Than the Cost of Gluten-Free Food

Celiac disease (CeD) is a chronic autoimmune disorder of global relevance, with the potential for acute and long-term complications. However, the economic burden of CeD is rarely considered and largely thought of as limited to the cost of gluten-free food. Fortunately, recent research has shed light on the various societal costs of CeD across the health care continuum. This article summarizes the current evidence on the economic impacts of CeD, which suggest that the societal economic burden of CeD stretches beyond the cost of gluten-free food. This review provides ample evidence of larger but hidden costs related to excess health care use for complications and comorbidities, as well as reduced productivity. Although significant advances are expected in the management of CeD, their effect on the economic burden of CeD remain uncertain. The aim of this review was to inform stakeholders across society and contribute to improved policies to support patients with CeD.

Celiac Disease-Related Conditions: Who to Test?

Celiac disease (CeD) is a chronic immune-mediated condition triggered by gluten consumption in genetically predisposed individuals. Approximately 1% of the general population is affected by the disorder. Disease presentation is heterogeneous and, despite growing awareness among physicians and the public, it continues to be underestimated. The most effective strategy for identifying undiagnosed CeD is proactive case finding through serologic testing in high-risk groups. We reviewed the most recent evidence on the association between CeD and more than 20 conditions. In light of this review, CeD screening is recommended in individuals with (1) autoimmune disease and accompanying symptoms suggestive of CeD; (2) diseases that may mimic CeD (eg, irritable bowel syndrome [IBS], inflammatory bowel disease [IBD], and microscopic colitis); and (3) among patients with conditions with a high CeD prevalence: first-degree relatives, idiopathic pancreatitis, unexplained liver enzyme abnormalities, autoimmune hepatitis, primary biliary cholangitis, hyposplenism or functional asplenia with severe bacterial infection, type 1 diabetes mellitus, Hashimoto's thyroiditis and Graves' disease, Sjögren's syndrome, dermatitis herpetiformis, recurrent aphthous syndrome and enamel defects, unexplained ataxia, peripheral neuropathy, delayed menarche or premature menopause, Down syndrome, Turner syndrome, Williams syndrome, chronic fatigue syndrome, IgA nephropathy, and IgA deficiency. CeD serology should be the initial step in the screening process. However, for patients with any of the aforementioned disorders who are undergoing upper endoscopy, biopsies should be performed to rule out CeD.

Stool Gluten Peptide Detection Is Superior to Urinary Analysis, Coeliac Serology, Dietary Adherence Scores and Symptoms in the Detection of Intermittent Gluten Exposure in Coeliac Disease: A Randomised, Placebo-Controlled, Low-Dose Gluten Challenge Study

Monitoring adherence to a gluten-free diet is an important goal of coeliac disease management. Urine and stool gluten immunogenic peptide (GIP) assays provide an objective readout of gluten ingestion, with the former favoured due to its convenience and acceptability. This study assessed stool GIP excretion after low-dose gluten challenge designed to mimic accidental gluten exposure. A total of 52 coeliac participants undertook a randomised, double-blind gluten (50-1000 mg) or placebo challenge. Stool and urinary GIP, serology, dietary adherence and symptoms were assessed. Stool GIP was 100% sensitive for gluten intake ≥250 mg and 71% for 50 mg. Peak GIP detection was 12-36 h after gluten exposure. The mean stool GIP after 1000 mg gluten ingestion remained above the limit of quantification for 5 days. Urine GIP assessment had poor sensitivity for GIP excretion compared to stool. Serology, dietary adherence score and symptoms did not correlate with gluten excretion during lead-in. We conclude that stool GIP detection is highly sensitive, with levels related to gluten dose and time from ingestion. Weekly or bi-weekly testing will detect low-level exposure more effectively than urine GIP assessments or traditional methods. In this seronegative, apparently well-treated cohort, a high frequency of baseline-positive GIP suggests ongoing gluten exposure, but the assessment of patient behaviour and assay specificity is needed.

Variation in Testing for and Incidence of Celiac Autoimmunity in Canada: A Population-Based Study

BACKGROUND & AIMS

The incidence of biopsy-confirmed celiac disease has increased. However, few studies have explored the incidence of celiac autoimmunity based on positive serology results.

METHODS

A population-based cohort study assessed testing of tissue transglutaminase antibodies (tTG-IgA) in Alberta from 2012 to 2020. After excluding prevalent cases, incident celiac autoimmunity was defined as the first positive tTG-IgA result between 2015 and 2020. Testing and incidence rates for celiac autoimmunity were calculated per 1000 and 100,000 person-years, respectively. Incidence rate ratios (IRRs) were calculated to identify differences by demographic and regional factors. Average annual percent changes (AAPCs) assessed trends over time.

RESULTS

The testing rate of tTG-IgA was 20.2 per 1000 person-years and remained stable from 2012 to 2020 (AAPC, 1.2%; 95% confidence interval [CI], -0.5 to 2.9). Testing was higher in female patients (IRR, 1.66; 95% CI, 1.65-1.66), those living in metropolitan areas (IRR, 1.39; 95% CI, 1.38-1.40), and in areas of lower socioeconomic deprivation (lowest compared to highest IRR, 1.24; 95% CI, 1.23-1.25). Incidence of celiac autoimmunity was 33.8 per 100,000 person-years and increased from 2015 to 2020 (AAPC, 6.2%; 95% CI, 3.1-9.5). Among those with tTG-IgA results ≥10 times the upper limit of normal, the incidence was 12.9 per 100,000 person-years. The incidence of celiac autoimmunity was higher in metropolitan settings (IRR, 1.28; 95% CI, 1.21-1.35) and in the least socioeconomically deprived areas compared to the highest (IRR, 1.22; 95% CI, 1.14-1.32).

CONCLUSIONS

Incidence of celiac autoimmunity is high and increasing, despite stable testing rates. Variation in testing patterns may lead to underreporting the incidence of celiac autoimmunity in nonmetropolitan areas and more socioeconomically deprived neighborhoods.

Coeliac Disease Case-Control Study: Has the Time Come to Explore beyond Patients at Risk?

The worldwide prevalence of asymptomatic coeliac disease (CD) is increasing, which is in part due to the routine screening of children with risk factors. Both symptomatic and asymptomatic patients with CD are at risk of long-term complications. The objective of this study was to compare the clinical characteristics of asymptomatic and symptomatic children at the time of CD diagnosis. A case-control study was conducted using data from a cohort of 4838 CD patients recruited from 73 centers across Spain between 2011 and 2017. A total of 468 asymptomatic patients (cases) were selected and matched by age and sex with 468 symptomatic patients (controls). Clinical data, including any reported symptoms, as well as serologic, genetic, and histopathologic data were collected. No significant differences were found between the two groups in most clinical variables, nor in the degree of intestinal lesion. However, the asymptomatic patients were taller (height z-score -0.12 (1.06) vs. -0.45 (1.19), p < 0.001) and were less likely to have anti transglutaminase IgA antibodies ≥ 10 times the upper normal limit (66.2% vs. 758.4%, p = 0.002). Among the 37.1% of asymptomatic patients who were not screened for CD due to the absence of risk factors, only 34% were truly asymptomatic, while the remaining 66% reported non-specific CD-related symptoms. Therefore, expanding CD screening to any child who undergoes a blood test could reduce the burden of care for some children, as many of those considered asymptomatic reported non-specific CD-related symptoms.

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.

Work Loss in Patients With Celiac Disease: A Population-based Longitudinal Study

BACKGROUND & AIMS

Celiac disease (CD) affects around 1% of the population worldwide. Data on work disability in patients with CD remain scarce. We estimated work loss in patients with CD, including its temporal relationship to diagnosis.

METHODS

Through biopsy reports from Sweden's 28 pathology departments, we identified 16,005 working-aged patients with prevalent CD (villus atrophy) as of January 1, 2015, and 4936 incident patients diagnosed with CD in 2008 to 2015. Each patient was matched to up to 5 general-population comparators. Using nationwide social insurance registers, we retrieved prospectively recorded data on compensation for sick leave and disability leave to assess work loss in patients and comparators.

RESULTS

In 2015, patients with prevalent CD had a mean of 42.5 lost work days as compared with 28.6 in comparators (mean difference, 14.7; 95% confidence interval [CI], 13.2-16.2), corresponding to a relative increase of 49%. More than one-half of the work loss (60.1%) in patients with CD was derived from a small subgroup (7%), whereas 75.4% had no work loss. Among incident patients, the annual mean difference between patients and comparators was 8.0 days (range, 5.4-10.6 days) of lost work 5 years before CD diagnosis, which grew to 13.7 days (range, 9.1-18.3 days) 5 years after diagnosis. No difference in work loss was observed between patients with or without mucosal healing at follow-up.

CONCLUSIONS

Patients with CD lost more work days than comparators before their diagnosis, and this loss increased after diagnosis. Identifying patients with an increased risk of work loss may serve as a target to mitigate work disability, and thereby reduce work loss, in patients with CD.

The global burden of coeliac disease: opportunities and challenges

Coeliac disease is a systemic disorder characterized by immune-mediated enteropathy, which is caused by gluten ingestion in genetically susceptible individuals. The clinical presentation of coeliac disease is highly variable and ranges from malabsorption through solely extra-intestinal manifestations to asymptomatic. As a result, the majority of patients with coeliac disease remain undiagnosed, misdiagnosed or experience a substantial delay in diagnosis. Coeliac disease is diagnosed by a combination of serological findings of disease-related antibodies and histological evidence of villous abnormalities in duodenal biopsy samples. However, variability in histological grading and in the diagnostic performance of some commercially available serological tests remains unacceptably high and confirmatory assays are not readily available in many parts of the world. Currently, the only effective treatment for coeliac disease is a lifelong, strict, gluten-free diet. However, many barriers impede patients' adherence to this diet, including lack of widespread availability, high cost, cross-contamination and its overall restrictive nature. Routine follow-up is necessary to ensure adherence to a gluten-free diet but considerable variation is evident in follow-up protocols and the optimal disease management strategy is not clear. However, these challenges in the diagnosis and management of coeliac disease suggest opportunities for future research.

Society for the Study of Celiac Disease position statement on gaps and opportunities in coeliac disease

Progress has been made in understanding coeliac disease, a relatively frequent and underappreciated immune-mediated condition that occurs in genetically predisposed individuals. However, several gaps remain in knowledge related to diagnosis and management. The gluten-free diet, currently the only available management, is not curative or universally effective (some adherent patients have ongoing duodenal injury). Unprecedented numbers of emerging therapies, including some with novel tolerogenic mechanisms, are currently being investigated in clinical trials. In March 2020, the Celiac Disease Foundation and the Society for the Study of Celiac Disease convened a consensus workshop to identify high-yield areas of research that should be prioritized. Workshop participants included leading experts in clinical practice, academia, government and pharmaceutical development, as well as representatives from patient support groups in North America. This Roadmap summarizes key advances in the field of coeliac disease and provides information on important discussions from the consensus approach to address gaps and opportunities related to the pathogenesis, diagnosis and management of coeliac disease. The morbidity of coeliac disease is often underestimated, which has led to an unmet need to improve the management of these patients. Expanded research funding is needed as coeliac disease is a potentially curable disease.

Reliability of the Multiplex CytoBead CeliAK Immunoassay to Assess Anti-tTG IgA for Celiac Disease Screening

Background and Objective: The diagnosis of Celiac Disease (CD) is first based on the positivity for specific serological markers. The CytoBead CeliAK immunoassay simultaneously measures antibodies (IgA) directed to tissue transglutaminase (tTG), endomysium (EMA), and deamidated gliadin (DG), in addition to providing a control for total IgA levels. The aim of this study is to assess the reliability of this multiplex assay to detect anti-tTG IgA positive patients, compared with a conventional single-parameter enzyme-linked immunosorbent assay (ELISA).

Methods: Serum samples from 149 pediatric patients were assessed by both CytoBead CeliAK immunoassay and ELISA, in order to evaluate their concordance for the measurement of anti-tTG IgA.

Results: The measurement of anti-tTG IgA by CytoBead CeliAK immunoassay basically showed a complete concordance rate with the conventional and single-parameter ELISA, according to the respective cutoff values (3 U/ml and 10 U/ml).

Conclusions: Our comparative analysis demonstrates a substantial equivalency between multiplex CytoBead CeliAK assay and the single-parameter conventional ELISA to assess anti-tTG IgA antibody in the context of the screening for CD in children. Importantly, CytoBead CeliAK assay could present some preanalytic, analytic, and economic advantages.

Nutritional implications of dietary gluten avoidance among Canadians: results from the 2015 Canadian Community Health Survey

Adherence to a gluten-free diet (GFD) is the only available treatment for gluten-related disorders, although a GFD may also be followed for discretionary reasons. The main objectives of the present study were to (1) describe and test for differences in key nutrient intakes among Canadians who follow a GFD compared with Canadians with no dietary exclusions and (2) describe additional dietary avoidances adhered to by Canadians who avoid gluten. We conducted a secondary analysis of the cross-sectional 2015 Canadian Community Health Survey-Nutrition Survey, which included a general health survey and 24-h dietary recall (n 20 487). Participants were categorised as those who avoid dietary gluten and those who reported no avoidances. Key nutrient intakes were assessed, as a percentage of Dietary Recommended Intakes, including fibre, B vitamins, vitamin D, Ca, Fe, Na and Zn, and compared between the two groups using t tests. Canadians who avoided gluten had significantly lower intakes of folate, vitamin B12, vitamin D, Fe, Na and Ca compared with those who did not avoid any food groups. However, Canadians who reported following a GFD were significantly more likely to use vitamin or mineral supplements in the past 30 d. More than 20 % of those who avoided gluten also avoided dairy products. Findings suggest that following a GFD places Canadians at risk for nutrient inadequacies, particularly folate, Ca and vitamin D. Further research is required to further examine how multiple dietary avoidances among those who avoid gluten may contribute to dietary inadequacies.

Gluten in pharmaceutical products: a scoping review

BACKGROUND

Celiac disease (CD) is one of the most common gluten-related disorders. Although the only effective treatment is a strict gluten-free diet, doubts remain as to whether healthcare professionals take this restriction into consideration when prescribing and dispensing medicines to susceptible patients. This scoping review aimed to find out the current evidence for initiatives that either describe the gluten content of medicines or intend to raise awareness about the risk of prescribing and dispensing gluten-containing medicines in patients with CD and other gluten-related disorders.

METHODS

A scoping review was conducted using three search strategies in PubMed/MEDLINE, TripDatabase and Web of Science in April 2021, following the PRISMA extension for scoping reviews (PRISMA-ScR). References from included articles were also examined. Two researchers screened the articles and results were classified according to their main characteristics and outcomes, which were grouped according to the PCC (Population, Concept and Context) framework. The initiatives described were classified into three targeted processes related to gluten-containing medicines: prescription, dispensation and both prescription and dispensation.

RESULTS

We identified a total of 3146 records. After the elimination of duplicates, 3062 articles remained and ultimately 13 full texts were included in the narrative synthesis. Most studies were conducted in the US, followed by Canada and Australia, which each published one article. Most strategies were focused on increasing health professional's knowledge of gluten-containing/gluten-free medications (n = 8), which were basically based on database development from manufacturer data. A wide variability between countries on provided information and labelling of gluten-containing medicines was found.

CONCLUSION

Initiatives regarding the presence of gluten in medicines, including, among others, support for prescribers, the definition of the role of pharmacists, and patients' adherence problems due to incomplete labelling of the medicines, have been continuously developed and adapted to the different needs of patients. However, information is still scarce, and some aspects have not yet been considered, such as effectiveness for the practical use of solutions to support healthcare professionals.

Systematic review: Exploration of the impact of psychosocial factors on quality of life in adults living with coeliac disease

BACKGROUND

Individuals living with coeliac disease generally experience a remission of symptoms after adopting the gluten-free diet but often report substantial treatment burden and ongoing quality of life issues. Psychosocial factors have been suggested to play a significant role in post-diagnosis quality of life but have yet to be systematically reviewed.

AIM

To review the evidence for psychosocial factors associated with quality of life in adult coeliac disease cohorts.

METHODS

Studies were identified via systematic searches of eight databases (MEDLINE, Embase, Emcare, PsycINFO, Ovid Nursing, CINAHL, Informit Health Collection, Cochrane Library) in May 2019.

RESULTS

Fourteen studies were included involving 3372 participants (80.2% female, mean age = 46.4 years). Symptoms of depression and anxiety were the most examined psychosocial factors across all studies. Quality of life was differentially associated with psychological distress, illness perceptions, coping, and attitudes/behaviours regarding food and the gluten-free diet.

CONCLUSION

Several psychosocial factors are associated with quality of life in adults living with coeliac disease. Current evidence suggests these factors are interrelated and may influence quality of life directly, via reduced psychological well-being, and indirectly, via reduced adherence to the gluten-free diet. Future research is needed to examine these processes concurrently, with the aim of elucidating the psychosocial mechanisms underlying post-diagnosis well-being and identifying potential targets for psychosocial intervention.

Association Between Celiac Disease and Autism Spectrum Disorder: A Systematic Review

OBJECTIVE

The aim of the study was to perform a systematic review assessing the research investigating the association between celiac disease (CD) and autism spectrum disorder (ASD).

METHODS

A literature search of MEDLINE and EMBASE was performed without limits placed on year or language. Observational studies reporting on the occurrence of CD among patients with ASD and/or the occurrence of ASD among patients with CD were included. Study design, characteristics, diagnostic criteria for ASD and CD, and the frequency of positive cases in the studied sample were recorded. Study quality was assessed using an adapted Newcastle-Ottawa Quality Assessment Scale. Due to substantial heterogeneity between studies, a meta-analysis was not performed.

RESULTS

Of the 298 unique citations identified within our search strategy, 17 articles evaluating the association between CD and ASD were included. Of those articles, 13 observed samples of patients with ASD, and 6 observed samples of patients with CD. Overall, most studies had small sample sizes and reported no evidence for an association between the 2 conditions. However, a limited number of population-based studies of higher quality suggested a potential association between CD and ASD.

CONCLUSIONS

Most studies assessing an association between CD and ASD are at risk for systematic and/or random error. A potential link has, however, been shown in a handful of high-quality studies, and, therefore, this comorbidity cannot be ruled out. Future studies should recruit larger sample sizes, include precise definitions of CD and ASD, and exclude patients with ASD on a gluten-free diet.

Mass Screening for Celiac Disease: The Autoimmunity Screening for Kids Study

INTRODUCTION

The Autoimmunity Screening for Kids (ASK) study is a large scale pediatric screening study in Colorado for celiac disease (CD) and type 1 diabetes. This is a report of the CD outcomes for the first 9,973 children screened through ASK.

METHODS

ASK screens children aged 1-17 years for CD using 2 highly sensitive assays for tissue transglutaminase autoantibodies (TGA): a radiobinding (RBA) assay for IgA TGA and an electrochemiluminescence (ECL) assay that detects all TGA isotypes. Children who test positive on either assay are asked to return for confirmatory testing. Those with a confirmed RBA TGA level ≥ 0.1 (twice the upper limit of normal) are referred to the Colorado Center for Celiac Disease for further evaluation; all others are referred to primary care.

RESULTS

Of the initial 9,973 children screened, 242 children were TGA+ by any assay. Of those initially positive, 185 children (76.4%) have completed a confirmation blood draw with 149 children (80.5%) confirming positive by RBA TGA. Confirmed RBA TGA+ was associated with a family history of CD (odds ratio [OR] = 1.83; 95% confidence interval 1.06-3.16), non-Hispanic white ethnicity (OR = 3.34; 2.32-4.79), and female sex (OR = 1.43; 1.03-1.98). Gastrointestinal symptoms of CD, assessed at the initial screening, were reported equally often among the RBA TGA+ vs TGA- children (32.1% vs 30.5%, P = 0.65).

DISCUSSION

The initial results of this ongoing mass-screening program confirm a high prevalence of undiagnosed CD autoimmunity in a screened US population. Symptoms at initial screening were not associated with TGA status (see Visual abstract, Supplementary Digital Content 5, http://links.lww.com/AJG/B587).

Adherence to a gluten-free diet and quality of life in Chilean celiac patients

INTRODUCTION

a gluten-free diet (GFD) is the treatment for celiac disease (CD), with adherence oscillating between 42 % and 91 %. The purpose of this study was to assess adherence to GFD and its relation to quality of life in Chilean celiac patients.

METHODS

three surveys were performed on-line: sociodemographic-health status, adherence to GFD and quality of life.

RESULTS

forty-eight per cent of respondents reported an excellent adherence to GFD and 49 % a good quality of life.

CONCLUSIONS

adherence to GFD is low among Chilean celiac patients.

Accuracy of potential diagnostic indicators for coeliac disease: a systematic review protocol

INTRODUCTION

Coeliac disease (CD) is a systemic immune-mediated disorder triggered by gluten in genetically predisposed individuals. CD is diagnosed using a combination of serology tests and endoscopic biopsy of the small intestine. However, because of non-specific symptoms and heterogeneous clinical presentation, diagnosing CD is challenging. Early detection of CD through improved case-finding strategies can improve the response to a gluten-free diet, patients' quality of life and potentially reduce the risk of complications. However, there is a lack of consensus in which groups may benefit from active case-finding.

METHODS AND ANALYSIS

We will perform a systematic review to determine the accuracy of diagnostic indicators (such as symptoms and risk factors) for CD in adults and children, and thus can help identify patients who should be offered CD testing. MEDLINE, Embase, Cochrane Library and Web of Science will be searched from 1997 until 2020. Screening will be performed in duplicate. Data extraction will be performed by one and checked by a second reviewer. Disagreements will be resolved through discussion or referral to a third reviewer. We will produce a narrative summary of identified prediction models. Studies, where 2×2 data can be extracted or reconstructed, will be treated as diagnostic accuracy studies, that is, the diagnostic indicators are the index tests and CD serology and/or biopsy is the reference standard. For each diagnostic indicator, we will perform a bivariate random-effects meta-analysis of the sensitivity and specificity.

ETHICS AND DISSEMINATION

Results will be reported in peer-reviewed journals, academic and public presentations and social media. We will convene an implementation panel to advise on the optimum strategy for enhanced dissemination. We will discuss findings with Coeliac UK to help with dissemination to patients. Ethical approval is not applicable, as this is a systematic review and no research participants will be involved.

PROSPERO REGISTRATION NUMBER

CRD42020170766.

Gluten-Free Casein-Free Diet for Autism Spectrum Disorders: Can It Be Effective in Solving Behavioural and Gastrointestinal Problems?

Autism spectrum disorder [ASD] is characterized by deficits in communication and social interactions combined with repetitive and restricted patterns of behaviors. Bidirectional changes in brain-gut microbiota are known to be responsible for the pathophysiology of many brain-related disorders, such as autism, as well as well-known gastrointestinal diseases, including gut disorders. Imbalance in the composition of gut microbiota is frequently observed in individuals with ASD. It is therefore believed that this imbalance is significant in the frequent occurrence of gastrointestinal symptoms. The integrity of the intestinal barrier and the blood-brain barrier [BBB] in individuals with ASD is affected. Incompletely digested peptides, toxins, and proinflammatory cytokines cross the BBB by entering the bloodstream and reach the central nervous system. As a result of the accumulation of these elements, brain function is adversely affected. It is hypothesized that incompletely digested peptides acting as opioid agonists reduce pain sensitivity and increase the severity of autism-specific behaviors. However, it is not known exactly how opioid peptides trigger ASD symptoms after they reach the brain. Diet therapies, especially elimination diets, are considered to be an alternative treatment to prevent this condition. Gluten-free casein-free [GFCF] diet is an elimination diet that involves the removal of certain proteins from the normal diet, such as gluten and casein. However, studies that demonstrate the beneficial effects of the GFCF diet on ASD patients and explain its mechanism is limited, which supports the opioid theory. This review aims to investigate the gastrointestinal and behavioral problems that are frequently observed in ASD, the possible action mechanisms of GFCF diets, and the efficacy of these elimination diets.

Costs and Use of Health Care in Patients With Celiac Disease: A Population-Based Longitudinal Study

INTRODUCTION

Celiac disease (CD) affects 1% of the population. Its effect on healthcare cost, however, is barely understood. We estimated healthcare use and cost in CD, including their temporal relationship to diagnosis.

METHODS

Through biopsy reports from Sweden's 28 pathology departments, we identified 40,951 prevalent patients with CD (villous atrophy) as of January 1, 2015, and 15,086 incident patients with CD diagnosed in 2008-2015, including 2,663 who underwent a follow-up biopsy to document mucosal healing. Each patient was compared with age- and sex-matched general population comparators (n = 187,542). Using nationwide health registers, we retrieved data on all inpatient and nonprimary outpatient care, prescribed diets, and drugs.

RESULTS

Compared with comparators, healthcare costs in 2015 were, on average, $1,075 (95% confidence interval, $864-1,278) higher in prevalent patients with CD aged <18 years, $715 ($632-803) in ages 18-64 years, and $1,010 ($799-1,230) in ages ≥65 years. Half of all costs were attributed to 5% of the prevalent patients. Annual healthcare costs were $391 higher 5 years before diagnosis and increased until 1 year after diagnosis; costs then declined but remained 75% higher than those of comparators 5 years postdiagnosis (annual difference = $1,044). Although hospitalizations, nonprimary outpatient visits, and medication use were all more common with CD, excess costs were largely unrelated to the prescription of gluten-free staples and follow-up visits for CD. Mucosal healing in CD did not reduce the healthcare costs.

DISCUSSION

The use and costs of health care are increased in CD, not only before, but for years after diagnosis. Mucosal healing does not seem to lower the healthcare costs.

Carrier frequency of HLA-DQB1*02 allele in patients affected with celiac disease: A systematic review assessing the potential rationale of a targeted allelic genotyping as a first-line screening

BACKGROUND

Celiac Disease (CD) is an immune-mediated disorder, in which the HLA immunogenetic background (DQ2 and DQ8 heterodimers) and environmental trigger (gluten) are well established. Indeed, both factors are necessary – but not sufficient – to develop CD. However, it is very likely that CD is underdiagnosed in both developing and developed countries, due to several aspects, including the fact that a lot of patients present mild and/or atypical symptoms, without the presence of any recognized risk factors. Therefore, the possibility and feasibility of widened screening strategies to identify CD patients are debated.

AIM

To provide further evidence of the main epidemiological importance of HLA-DQB1*02 allele in the population of CD patients.

METHODS

We performed a systematic search in PubMed, EMBASE, Cochrane, Web of Science and Scopus databases, in order to produce a systematic review assessing the carrier frequency of HLA-DQB1*02 allele in the celiac population. Following the PRISMA guidelines, we retrieved all the original articles describing CD patients’ HLA-DQB1 genotype in such a way that could allow to assess the HLA-DQB1*02 carrier frequency among CD patients, along with the evidence of the appropriate diagnostic work-up to achieve a correct and final diagnosis of CD.

RESULTS

The final output of this systematic search in the medical literature consisted of 38 studies providing the appropriate HLA-DQB1 genotype information of the respective CD population. According to this systematic review, including a pool of 4945 HLA-DQ genotyped CD patients, the HLA-DQB1*02 carrier frequency was 94.94%, meaning that only 5.06% of CD patients were completely lacking this allelic variant. Interestingly, if we consider only the studies whereby the prevalence of CD patients affected with type 1 diabetes mellitus was supposed or clearly established to be very low, the frequency of non-HLA-DQB1*02 carriers among CD patients dropped to 3.65%.

CONCLUSION

Such a high carrier frequency of the HLA-DQB1*02 allelic variant (which is > 95%-96% in CD patients without risk factors, like type 1 diabetes mellitus comorbidity) might be exploited to consider a cost-effective and widened screening approach. If a sustainable strategy could be implemented through a low-cost targeted genetic test to detect the individual presence of HLA-DQB1*02 allele, an appropriate algorithm for serological screening in individuals resulting to be genetically predisposed to CD, might be considered.

Preparation and Characterization of Avenin-Enriched Oat Protein by Chill Precipitation for Feeding Trials in Celiac Disease

The safety of oats for people with celiac disease remains unresolved. While oats have attractive nutritional properties that can improve the quality and palatability of the restrictive, low fiber gluten-free diet, rigorous feeding studies to address their safety in celiac disease are needed. Assessing the oat prolamin proteins (avenins) in isolation and controlling for gluten contamination and other oat components such as fiber that can cause non-specific effects and symptoms is crucial. Further, the avenin should contain all reported immunogenic T cell epitopes, and be deliverable at a dose that enables biological responses to be correlated with clinical effects. To date, isolation of a purified food-grade avenin in sufficient quantities for feeding studies has not been feasible. Here, we report a new gluten isolation technique that enabled 2 kg of avenin to be extracted from 400 kg of wheat-free oats under rigorous gluten-free and food grade conditions. The extract consisted of 85% protein of which 96% of the protein was avenin. The concentration of starch (1.8% dry weight), β-glucan (0.2% dry weight), and free sugars (1.8% dry weight) were all low in the final avenin preparation. Other sugars including oligosaccharides, small fructans, and other complex sugars were also low at 2.8% dry weight. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of the proteins in these preparations showed they consisted only of oat proteins and were uncontaminated by gluten containing cereals including wheat, barley or rye. Proteomic analysis of the avenin enriched samples detected more avenin subtypes and fewer other proteins compared to samples obtained using other extraction procedures. The identified proteins represented five main groups, four containing known immune-stimulatory avenin peptides. All five groups were identified in the 50% (v/v) ethanol extract however the group harboring the epitope DQ2.5-ave-1b was less represented. The avenin-enriched protein fractions were quantitatively collected by reversed phase HPLC and analyzed by MALDI-TOF mass spectrometry. Three reverse phase HPLC peaks, representing ~40% of the protein content, were enriched in proteins containing DQ2.5-ave-1a epitope. The resultant high quality avenin will facilitate controlled and definitive feeding studies to establish the safety of oat consumption by people with celiac disease.