A rapid antibody test had high specificity but low sensitivity for diagnosing coeliac disease

ED FROM Korponay-Szabo IR, Szabados K, Pusztai J, et al. Population screening for coeliac disease in primary care by district nurses using a rapid antibody test: diagnostic accuracy and feasibility study. BMJ 2007;335:1244–7. Correspondence to: Dr M Maki, Tampere University Hospital and Medical School, Tampere, Finland; markku.maki@uta.fi Source of funding: Hungarian Scientific Research Fund; Hungarian Ministry of Health; Research Fund of Tampere University Hospital; EU Marie Curie. c Clinical impact ratings: GP/FP/Primary care 6/7; Allergy & immunology 6/7; Gastroenterology 6/7; Paediatrics 6/7; Public health 5/7 Diagnostic test characteristics of a rapid antibody test compared with other reference tests for coeliac disease in children* Reference tests Sensitivity (95% CI) Specificity (CI) +LR 2LR Small bowel biopsy 78% (70 to 89) 100% (88 to 100) ‘ 0.2 Combined IgA + IgG tests 65% (50 to 78) 100% (100 to 100) ‘ 0.4 *Diagnostic terms defined in glossary. LRs calculated from sensitivities and specificities in article. C O M M EN TA R Y T he gold standard for diagnosing coeliac disease is intestinal biopsy. However, because biopsy is expensive and invasive, it is rarely the first test to detect coeliac disease in patients, nor can it be a screening examination for the general public. Current guidelines would recommend first obtaining autoantibodies against tissue transglutaminase or endomysium for evaluating children or adults with symptoms that could be explained by coeliac disease. Serodetection by tissue transglutaminase and endomysium is recommended to screen people at high risk of coeliac disease (ie, type 1 diabetes, autoimmune thyroiditis, and Down syndrome). Despite the rich vein of coeliac disease in these risk groups, most coeliac disease, affecting about 1% of the population, remains undiagnosed. While the natural history of covert coeliac disease is unknown, many patients will develop consequences with widely varying symptoms and resulting syndromes. The gluten-free diet is cheap and effective, and it may decrease morbidity and mortality. The study by Korponay-Szabo et al shows an effective community-based strategy for population screening. The quick and accessible screening test proposed would greatly increase the detection of coeliac disease and makes it practical to identify and intervene in these patients. Although the sensitivity of the bedside test is lower than endomysium (78% v 92– 100%), having a trusted health professional, who explained and administered the test, facilitated the subsequent evaluation. The practicality of this approach requires a robust community healthcare system. The study has some drawbacks. Transglutaminase ELISA testing was only carried out in the endomysium positive cases, which may reflect the expense of ELISA kits. So it is possible that somewhat different comparative results in terms of sensitivity may have been found if transglutaminase ELISA was done in the whole cohort. Human error in interpretation of the test results also modestly reduced the sensitivity. Jonathan D Godfrey, MD Joseph A Murray, MD Mayo Clinic, Rochester, Minnesota, USA 1. Rostom A, Murray JA, Kagnoff MF. American Gastroenterological Association (AGA) Institute technical review on the diagnosis and management of celiac disease. Gastroenterology 2006;131:1981–2002. 2. Hill ID, Dirks MH, Liptak GS, et al. Guideline for the diagnosis and treatment of celiac disease in children: recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. J Pediatr Gastroenterol Nutr 2005;40:1–19. 3. Hoffenberg EJ, MacKenzie T, Barriga KJ, et al. A prospective study of the incidence of childhood celiac disease. J Pediatr 2003;143:308–14. Diagnosis 118 EBM August 2008 Vol 13 No 4