This post is about some basics of celiac disease from the reference below.
What follows is The U.S. Preventive Services Task Force Final Recommendation Statement Celiac Disease: Screening (March 2017):
The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for celiac disease in asymptomatic persons. [Emphasis added]
Importance
Celiac disease is a multisystem autoimmune disorder in genetically predisposed adults and children that is triggered by dietary gluten. Ingestion of gluten by persons with celiac disease causes immune-mediated inflammatory damage to the small intestine, which can cause gastrointestinal and nongastrointestinal illness. The clinical presentation, severity of symptoms, and natural history of the disease varies and includes asymptomatic (or “silent”) celiac disease.
In studies of US populations, the estimated prevalence of celiac disease among adults ranges from 0.40% to 0.95%.1 Prevalence is higher than average among non-Hispanic whites, persons with a family history of celiac disease, and persons with other autoimmune conditions.2
Burden of Disease
Celiac disease is caused by an immune response in persons who are genetically susceptible to dietary gluten, a protein complex found in wheat, rye, and barley. Ingestion of gluten by persons with celiac disease causes immune-mediated inflammatory damage to the small intestine mucosa, resulting in malabsorption of nutrients.
Celiac disease can have several different presentations. Classic celiac disease is associated with diarrhea, abdominal pain, and weight loss. However, celiac disease is also associated with nongastrointestinal, nonspecific manifestations of disease such as anemia, osteoporosis, chronic fatigue, peripheral neuropathy or ataxia, aphthous stomatitis, dermatitis herpetiformis, infertility, recurrent fetal loss, or short stature.3 Children may also experience pubertal delay and dental enamel defects.22 For patients with subclinical disease, symptoms may be mild and not recognized until after initiation of a gluten-free diet. Patients with silent, or asymptomatic, celiac disease have been diagnosed by serologic testing and intestinal biopsy but do not have the typical signs or symptoms of celiac disease. Patients with potential celiac disease have positive serology findings and mild or no intestinal damage on biopsy; they may or may not have symptoms. The natural history of silent and potential celiac disease is not well understood, and it is not clear if they represent progressive stages of celiac disease or distinct subtypes.2
Data on the prevalence of silent celiac disease in the United States, as well as the proportion of these individuals who later develop symptomatic celiac disease, are limited.2 Reported prevalence of celiac disease in the literature varies due to the different racial/ethnic populations studied and the method used to confirm diagnosis.2 In a systematic review of 38 studies from North America and Western Europe, prevalence was similar among studies that included biopsy confirmation (0.15% to 1.90%) and among studies that did not (0.15% to 2.70%).1 In the 3 US-based studies, prevalence among adults ranged from 0.40% to 0.95%.1
Accuracy of Screening Tests
A recent good-quality systematic review on the accuracy of diagnostic tests for celiac disease, which included studies enrolling both persons with symptoms and those whose symptom status was not described, found high strength of evidence that the tTG IgA test has high (>90%) sensitivity and specificity and endomysial antibody (EMA) IgA tests have high specificity, based on consistent results from prior systematic reviews and new studies.24 This systematic review included only 2 studies reporting diagnostic accuracy in asymptomatic persons at higher risk for celiac disease, due to other autoimmune disorders or family history, and no studies in asymptomatic persons at average risk. These 2 cross-sectional studies, which were both conducted outside the United States, found lower sensitivity and specificity for the tTG and EMA IgA tests (sensitivity, 57% to 71%; specificity, 83% to 98%), compared with studies that did not restrict enrollment to asymptomatic patients. One study was conducted in Iraq among patients with type 1 diabetes mellitus, no symptoms of celiac disease, and no family history of celiac disease or thyroid disorders. Sensitivity was 71% for both the tTG and EMA IgA tests and specificity was 93% for the tTG test and 96% for the EMA IgA test.25 The second study was conducted in the Czech Republic among children and adolescents at higher risk for celiac disease due to family history or a diagnosis of type 1 diabetes mellitus. Among asymptomatic patients, specificity and sensitivity of detecting antitransglutaminase levels of more than 10 times the upper limit of normal and a positive EMA IgA test result in patients with a Marsh histologic classification of stage 2 or 3 were 67% and 83%, respectively. Among first-degree relatives of patients with celiac disease (n=32), specificity was 70% and sensitivity was 81%. Among patients with type 1 diabetes mellitus (n=40), specificity was 64% and sensitivity was 93%.26
Recommendations of Others
The American Academy of Family Physicians has concluded that the current evidence is insufficient to assess the balance of benefits and harms of screening for celiac disease in asymptomatic persons.28 The American College of Gastroenterology recommends that asymptomatic persons with a first-degree relative who has a confirmed diagnosis of celiac disease be considered for testing. Patients with type 1 diabetes mellitus should be tested for celiac disease if there are any digestive symptoms, signs, or laboratory evidence suggestive of celiac disease.15
The National Institute for Health and Care Excellence recommends offering serologic testing to persons with a first-degree relative with celiac disease or persons with type 1 diabetes mellitus or autoimmune thyroid disease on diagnosis. Serologic testing for celiac disease should be considered for persons with any of the following: metabolic bone disorder (reduced bone mineral density or osteomalacia), unexplained neurologic symptoms (particularly peripheral neuropathy or ataxia), unexplained subfertility or recurrent miscarriage, persistently elevated liver enzymes with unknown cause, dental enamel defects, Down syndrome, or Turner syndrome.16
The North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition recommends testing for celiac disease in asymptomatic children who have conditions associated with celiac disease (type 1 diabetes mellitus, autoimmune thyroiditis, Down syndrome, Turner syndrome, Williams syndrome, or selective IgA deficiency) or a first-degree relative with celiac disease. It recommends testing these children beginning around age 3 years, provided they have had an adequate gluten-containing diet for at least 1 year prior. It also recommends that asymptomatic, at-risk children with negative serology findings be considered for repeat testing.17
