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Accuracy of serologic tests and HLA-DQ typing for diagnosing celiac disease
Muhammed Hadithi1, B Mary E von Blomberg, J Bart A Crusius
1Department of Gastroenterology, Het Groene Hart Ziekenhuis, Gouda, The Netherlands. muhammed.hadithi@ghz.nl
Background:
Estimates of the diagnostic performance of serologic testing and HLA-DQ typing for detecting celiac disease have mainly come from case-control studies.
Objective:
To define the performance of serologic testing and HLA-DQ typing prospectively.
Design:
Prospective cohort study.
Setting:
University hospital.
Patients:
Patients referred for small-bowel biopsy for the diagnosis of celiac disease.
Interventions:
Celiac serologic testing (antigliadin antibodies [AGA], antitransglutaminase antibodies [TGA], and antiendomysium antibodies [EMA]) and HLA-DQ typing.
Measurements:
Diagnostic performance of serologic testing and HLA-DQ typing compared with a reference standard of abnormal histologic findings and clinical resolution after a gluten-free diet.
Results:
Sixteen of 463 participants had celiac disease (prevalence, 3.46% [95% CI, 1.99% to 5.55%]). A positive result on both TGA and EMA testing had a 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%). Testing positive for either HLA-DQ type maximized sensitivity (100% [CI, 79% to 100%]) and negative predictive value (100% [CI, 98.6% to 100%]), whereas testing negative for both minimized the negative likelihood ratio (0.00 [CI, 0.00 to 0.40]) and posttest probability (0% [CI, 0% to 1.4%]). The addition of HLA-DQ typing to TGA and EMA testing, and the addition of serologic testing to HLA-DQ typing, did not change test performance compared with either testing strategy alone.
Limitation:
Few cases of celiac disease precluded meaningful comparisons of testing strategies.
Conclusions:
In a patient population referred for symptoms and signs of celiac disease with a prevalence of celiac disease of 3.46%, TGA and EMA testing were the most sensitive serum antibody tests and a negative HLA-DQ type excluded 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 the same measures of test performance as either testing strategy alone.
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