The serological diagnosis of adult coeliac disease – a cautious step forward?

As described in a fascinating review by Holmes and Ciacci (1), the road to a ‘no biopsy’ serology-based diagnosis of adult coeliac disease (CD) makes perfect clinical sense. Who would want to have a gastroscopy if they can avoid it?! Furthermore, avoidance of gastroscopy and biopsy has the potential in the UK to be economical from the perspective of a cash-strapped NHS. There have been numerous studies supporting this approach (2,3). However, the positive predictive value (PPV) frequently cited of up to 100% for serological testing has its limitations (4-9). Many of the data sets are retrospective and from highly selected populations where the CD prevalence is high (6 studies, CD prevalence between 21-100%) (4-10). A unique endoscopy-based study, which has the advantage of 100% biopsy/histology being available, suggests less promising results. In this prospective study of 2000 unselected patients attending for endoscopy the CD prevalence was 3.9% (11). By contrast to the reported 100% PPV, this study demonstrates the PPV of tTG was only 28.6%, despite sensitivity and specificity of greater than 90%. This only increased to 71.7% when combined with a positive endomysial antibody (EMA) (11). We appreciate that this is a historical study using a recombinant human tissue transglutaminase (tTG) linked to gliadin-specific peptides.