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P246. Evaluation of a new point of care test for the screening of coeliac disease in an IgA deficient paediatric population

F. Bienvenu1, L. Garnier1, F. Renosi1, J. Guillemaud1, S.I. Anghel2, A. Lachaux3, C. Besson Duvanel2, J. Bienvenu1, 1Lyon-Sud Hospital, Immunology Laboratories, Pierre-Bénite, France, 2Augurix SA, Monthey, Switzerland, 3Lyon Paediatric Hospital, Gastroenterology Hepatology Nutrition Department, Bron, France

Background

The frequency of IgA deficiency (IgAD) is estimated to 1:40 among celiac disease patients (Chow et al, 2012).

Diagnosis of CD relies on the presence of anti-tissue transglutaminase (tTG) IgA autoantibodies. However, patients suffering from IgAD are often not aware of their IgA deficiency and are tested as CD negative, delaying considerably the diagnosis. It has been demonstrated that the detection of IgG against deamidated gliadin peptides (DGP), have high specificity and better sensitivity than IgG anti-tTG (Vermeersch et al, 2012).

A multi-analytic lateral-flow immunochromatographic assay (CD-LFIA) based on the detection of both IgA and IgG anti-DGP and total IgA was previously shown to have a good diagnostic accuracy for screening CD in paediatric populations (Bienvenu et al, 2012). The present study evaluates its use as a screening tool for CD in children suffering from IgAD.

Methods

54 IgAD paediatric patients (mean age: 7.6 years; range: 0.2–17 years) tested for clinical suspicion of CD (n = 21), for risk factors for CD (n = 18) or for monitoring of CD patients under gluten-free diet (GFD) (n = 5). Ten children were not clinically documented. The screening of CD was based on ELISA IgG tTG (Celikey®, Thermofisher). The serum samples were tested on the CD-LFIA test (Simtomax® Augurix, Switzerland).

Results

8 patients were diagnosed as new CD using IgG tTG and intestinal biopsy. All were correctly identified by the CD-LFIA.

The test yields five false positive results among which, one GFD patient and two other patients having ELISA Ig DGP levels above cut-off. DGP antibodies precede appearance of tTG in children (Liu et al, 2007).

The test also yields three false negative results among which, one GFD patient. Two other false negative patients had a positive ELISA IgG tTG result but were classified as CD negative based on patient follow-up.

The specificity and sensitivity of the test for DGP screening when compared to ELISA tTG, was of 88.4% and 72.3%, respectively, and the negative predictive value (NPV) was of 92.7%. These values are highly ameliorated using biopsies and follow-up results as reference.

Conclusion

CD-LFIA is an easily to perform and reliable assay to rule out CD. Its use can improve the management of IgAD paediatric patients showing symptoms related to CD. It can reduce the turnaround time for result delivery, patient counselling and treatment. Therefore, it can be used as a screening tool in a targeted IgA paediatric population.