Introduction Endoscopic markers of coeliac disease (CD) lack sensitivity; therefore many centres take routine duodenal biopsies or have a low threshold for biopsy, ensuring high detection rates. Newly available, point of care tests (POCT) provide rapid findings unlike conventional serological markers, potentially reducing the need for duodenal biopsies. This study evaluates a new POCT (Simtomax) which detects IgA and IgG deamidated gliadin peptide (DGP) with comparisons made to conventional serological markers and histology.
Methods Patients referred for a gastroscopy to a specialist CD list were prospectively recruited between March and November 2013. Patients were excluded if they were on a gluten free diet at the time of the test or if they had previously been diagnosed with seronegative villous atrophy. All patients had a duodenal biopsy as the gold standard for detecting CD. Concurrently serological testing for IgA tissue transglutaminase (TTG), endomysial antibody (EMA), total immunoglobulin A level and the DGP based rapid test was performed. Sensitivity, specificity, positive predictive (PPV) and negative predictive values (NPV) were calculated.
Results 354 patients met the inclusion criteria (45.8% male mean age 53.3 +18.5). Of these, 52 (14.7% 11.2 – 18.9) had newly diagnosed CD and 302 were controls with a normal duodenal biopsy. The sensitivity, specificity, PPV and NPV for the POCT were 94, 83, 49 and 99% respectively. This compares with results for TTG of 92, 88, 57, 99 and EMA of 88, 97, 85, and 98% respectively. In a second cohort, 43 patients with known CD for re-assessment were recruited (20.9% male, mean age 49.4 +16.6). 16 (37% 23 -53) of these 16 patients (37%) had persistent villous atrophy despite a gluten free diet. POCT compared to histology showed sensitivity of 88% and specificity 41%. tTG showed sensitivity and specificity of 63 and 70% respectively and EMA 56 and 78% respectively. However agreement between histology and POCT was poor with concordance between results in only 60% (κ=0.274). tTG and EMA were marginally better with κ=0.321 and κ=0.345 respectively.
Conclusion This is the first study to prospectively demonstrate the value of a novel POCT for adult CD in endoscopy compared to the gold standard of histology. The sensitivity and specificity of the POCT is comparable to conventional serology. Simtomax could be used to appropriately identify patients requiring a duodenal biopsy within the endoscopic setting. This strategy may be cost effective by reducing the number of routine duodenal biopsies taken. Further work is required to clarify the role of POCT for the assessment of histological remission in patients with known CD.
Disclosure of Interest None Declared.
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