TITLE: DIAGNOSTIC UTILITY OF CONVENTIONAL CELIAC DISEASE SPECIFIC MARKERS.

Background: Serology based diagnosis of celiac disease (CD) or patient selection for duodenal biopsy remains a dilemma. Objectives:This study was performed to assess the diagnostic accuracy of conventional CD specific serological markers. Patients and Methods: This retrospective study was performed at King Khalid University Hospital, Riyadh Saudi Arabia. Data were extracted from 237 patients investigated for CD between March 2012 and June 2014. Data for histological and serological assessment were available for 61/237 patients (36 females and 25 males; mean age28.3+14 years).CD was confirmed histologically in 37 (60.7%) patients. Results:Frequently detected antibodies were anti-gliadinIgG in 88.5% and anti-tissue transglutaminase IgA (a-Ttg IgA) antibodies in 65.6% patients. The most reliable marker for the diagnosis of CD was a-Ttg IgA with a sensitivity of 97%, specificity of 83%, positive predictive value (PPV) of 90% and a negative predictive value (NPV) of 95%. None of the other CD-specific marker matched the performance of a-Ttg IgA antibody. Performance of the composite marker developed using discriminant analysis surpassed all markers with a sensitivity of 97%, specificity of 92%, PPV of 95% and NPV of 96%. The area under curve for composite marker with 95% confidence interval was 96.7% (92%-100%) significantly higher (p=0.04) than that of a-Ttg 90.3% (82.3%-98.4%). The apparent prevalence of anti-gliadin IgA (62%) was almost similar to true prevalence (61%). Conclusion: For the diagnosis of CD a-Ttg IgA displayed a high level of diagnostic accuracy as an individual marker however the performance of composite marker was significantly higher than a-Ttg IgA.