Accuracy of Serologic Tests and HLA-DQ Typing for Diagnosing Celiac Disease

Celiac.com 09/28/2007 - Figures concerning the diagnostic accuracy of various serologic test and HLA-DQ typing for diagnosing celiac disease have largely come from case–control studies.

A team of doctors recently set out to assess the performance of serologic testing and HLA-DQ typing in the diagnosis of celiac disease. Results of their study were published recently in the Annals of Internal Medicine.

The team was made up of Muhammed Hadithi, MD; B. Mary E. von Blomberg, PhD; J. Bart A. Crusius, PhD; Elisabeth Bloemena, MD, PhD; Pieter J. Kostense, PhD; Jos W.R. Meijer, MD, PhD; Chris J.J. Mulder, MD, PhD; Coen D.A. Stehouwer, MD, PhD; and Amado S. Peña, MD, PhD

Their study looked at patients who had been referred for small bowel biopsy to determine weather they had celiac disease, and evaluated the effectiveness of serologic testing for celiac disease, specifically of antigliadin antibodies (AGA), antitransglutaminase antibodies (TGA), and anti-endomysium antibodies (EMA) and HLA-DQ typing.

Data was measured by comparing the performance of serologic testing and HLA-DQ against a reference baseline of abnormal histologic findings and clinical resolution after a gluten-free diet.

Of 463 participants, sixteen had celiac disease (prevalence = 3.46% [95% CI, 1.99% to 5.55%]).

Testing positive on both TGA and EMA showed a corresponding sensitivity of 81% (CI, 54% to 95.9%), specificity of 99.3% (CI, 98.0% to 99.9%), and negative predictive value of 99.3% (CI, 98.0% to 99.9%).

A positive test for either HLA-DQ type increased both sensitivity (100% [CI, 79% to 100%]) and negative predictive value (100% [CI, 98.6% to 100%]), while testing negative for both minimized the negative likelihood ratio (0.00 [CI, 0.00 to 0.40]) and post-test probability (0% [CI, 0% to 1.4%]). Adding HLA-DQ typing to TGA and EMA testing, and adding serologic testing to HLA-DQ typing, saw no corresponding difference in test performance compared with either testing strategy alone.

Overall results show TGA and EMA testing were the most sensitive serum antibody tests and a negative HLA-DQ type excluded the celiac disease from the diagnosis.

However, the addition of HLA-DQ typing to TGA and EMA testing, and the addition of serologic testing to HLA-DQ typing, provided no change of test performance compared with either form of testing alone.

Finally, the findings were somewhat limited, as low number of overall cases of celiac disease rule out meaningful comparisons of testing strategies.

Annals of Internal Medicine (volume 147, pages 294-302)