Positive predictive value of serological diagnostic measures in celiac disease

Celiac disease (CD) antibodies, immunoglobulin A (IgA) anti-tissue transglutaminase (anti-tTG), IgA endomysium antibody (EMA), IgA and IgG anti-gliadin antibodies (IgA and IgG AGA) are first-line diagnostic tools used in selecting patients for duodenal biopsy. The goal of this study was to evaluate the diagnostic quality of serological testing for CD.

CD serological tests (IgA and IgG AGA, anti-tTG and EMA) from 11,915 individuals were measured. Data were combined with clinical data and results of duodenal biopsy using a unique Danish personal identification number.

The positive predictive value (PPV) varied according to different combinations of positive CD antibodies, being highest when all antibodies were positive (97.6%). The anti-tTG concentration correlated strongly with EMA positivity, number of additional positive antibodies, and higher PPV. A logistic regression model predicted the probability of later biopsy-proven CD in relation to concentrations of IgA AGA and anti-tTG at initial serological screening.

The anti-tTG concentration at initial serological CD screening was highly informative in relation to EMA positivity, number of additional CD specific antibodies and PPV. Furthermore, in the high-risk group of patients investigated, the concentrations of anti-tTG and IgA AGA at initial serological screening could accurately predict the probability of future biopsy-proven CD.