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Testing for Celiac Disease
Abstract & Commentary
By Mary Elina Ferris, MD, Clinical Professor, University of Southern California. Dr. Ferris reports no financial relationship to this field of study.
Synopsis: Testing patients with abdominal symptoms for celiac disease in primary care settings using IgA tissue transglutaminase antibodies and IgA endomysial antibodies yielded high sensitivity and specificity, justifying their use widely for diagnosis.
Source: van der Windt DA, et al. Diagnostic testing for celiac disease among patients with abdominal symptoms. JAMA 2010;303:1738-1746.
Focusing specifically on studies in primary care settings or other outpatient clinics of adults with non-acute abdominal complaints, 16 research studies published since 1966, involving a total of 6085 patients, were identified for this review. Studies had to confirm celiac disease with small bowel biopsy for accuracy.
Chronic abdominal symptoms alone were not accurate in the diagnosis of celiac disease. For diarrhea, sensitivity varied from 0.27 to 0.86, and specificity from 0.21 to 0.86. Other symptoms such as constipation, weight loss, abdominal pain, nausea, and flatulence were even less specific and varied widely.
Using serum antibodies specific for celiac disease resulted in much higher diagnostic accuracy. For IgA tissue transglutaminase antibodies (IgA-tTG), sensitivity was 0.89 and specificity 0.98. With a disease prevalence of 5.5% in 4 cohort studies, the predictive value of IgA-tTG was 0.72 for a positive result and 0.99 for a negative result. For IgA endomysial antibodies (EmA), sensitivity was 0.90 and specificity 0.99. With a disease prevalence of 9% in 7 cohort studies, the predictive value of EmA was 0.90 for a positive result and 0.99 for a negative result. Other antibody tests, such as IgA diamidated gliadin peptide antibodies (IgG-DGP) or IgA antigliadin antibodies (IgA-AGA), gave variable results.
Since the clinical presentation of celiac disease can vary from silent to a broad spectrum of vague abdominal symptoms, deciding when diagnostic testing is justified can be perplexing. Estimated prevalence rates for celiac disease in patients presenting with abdominal pain are 2%-4%, and since the disease can have significant consequences (infertility, osteoporosis, malignancy) and is treatable with a gluten-free diet, it is important to identify this condition. The prevalence of celiac disease in patients with irritable bowel syndrome (IBS) is estimated to be twice as high compared to those without IBS.1
This review confirms what primary care clinicians surely know about the non-specific nature of most non-urgent abdominal complaints: None are specific for a particular disease, but diarrhea is more likely to be associated with celiac disease than other complaints. The sensitivity of the EmA antibody test would seem to make it the likely choice for a first screen, but, unfortunately, studies in clinical use have found it more complex and user-dependent compared to the automated and less expensive IgA-tTG test.2,3
Therefore, the current recommendation for the most accurate celiac disease screening tests in outpatient settings is to use both the IgA-tTG and EmA serum antibody tests. A strategy of sequential testing, using IgA-tTG first, followed by EmA and possible small bowel biopsy, may have promise, but has not been adequately studied. Clinicians can expect to receive lots of negative results, but should be encouraged to freely utilize this testing for celiac disease in the hope of detecting a significant, treatable disease.
1. Ford AC, et al. Yield of diagnostic tests for celiac disease in individuals with symptoms suggestive of irritable bowel syndrome: Systematic review and meta-analysis. Arch Intern Med 2009;169:651-658.
2. Tesei N, et al. Antibodies to human recombinant tissue transglutaminase may detect coeliac disease patients undiagnosed by endomysial antibodies. Aliment Pharmacol Ther 2003;17:1415-1423.
3. Akbari MR, et al. Screening of the adult population in Iran for coeliac disease: Comparison of the tissue-transglutaminase antibody and anti-endomysial antibody tests. Eur J Gastroenterol Hepatol 2006;18:1181-1186.