Diagnostic accuracy of a point-of-care test for celiac disease antibody screening among infertile patients

Abstract

Background: Screening for celiac disease among infertile patients has been suggested. Several rapid point-of-care (POC) tests aimed at detecting celiac disease antibodies have been developed. It has been suggested that these POC tests can be implemented as a replacement for standard laboratory tests. Objective: To evaluatethe diagnostic accuracy of a POC test (Simtomax®) that detects celiac disease antibodies compared with standard laboratory tests when screening for celiac disease among patients referred for fertility treatment in 2 Danish fertility clinics. Methods: Serum samples were analyzed for IgA anti-tissue transglutaminase (TGA) as the reference standard test with a cutoff of ≥7 kU/L and by the index POC test based on IgA and IgG antibodies against deamidated gliadin peptides (DGP). In IgA deficiency, the reference standard test was IgG DGP with a cutoff of ≥7 kU/L. Participants answered a questionnaire on gluten intake, symptoms, and risk factors. Diagnostic confirmation was made by duodenal biopsies. IgA TGA/IgG DGP were used as the reference standard to calculate positive and negative predictive values. Results: A total of 622 men and women (51.6%) were enrolled during 2015. The reference standard IgA TGA/IgG DGP was positive in 7 participants (1.1% [95% CI 0.5-2.3]) and the POC test was positive in 84 participants (13.5% [95% CI 10.9-16.4]), 3 of whom also had positive reference standard tests. This yields a sensitivity of the index POC test of 42.9% (95% CI 9.9-81.6) and a specificity of 86.8% (95% CI 83.9-89.4). Positive and negative predictive values were 3.57% (95% CI 0.7-10.1) and 99.3% (95% CI 98.1-99.8). Conclusion: The sensitivity of the POC test was low; however, the specificity was moderately good. The POC test had a high negative predictive value in this low prevalent population but missed 1 patient with biopsy-confirmed celiac disease. However, because of many false-positive tests, it cannot be recommended as replacement for standard laboratory tests but rather as a triage test to decide if the standard serology tests should be performed.