No 10, 2012

Publication of the Month

 

 

October 10/12: 

Serologic strategies for celiac disease diagnosis  

 

Key message:

  • Determination of tTG IgA and DGP IgG is the best strategy for the diagnosis of celiac disease.
  • The use of likelihood ratios improves the clinical interpretation of serologic testing for CD.

 

Vermeersch P, Geboes K, Marien G, Hoffman I, Hiele M, Bossuyt X
Serological diagnosis of celiac disease: Comparative analysis of different strategies
Clin. Chim. Acta 2012; 413: 1761–1767

 

Background:
The detection of antibodies against tissue transglutaminase (tTG) and deamidated gliadin peptide (DGP) are valuable tools in the diagnosis of celiac disease (CD).
This study evaluates the diagnostic performance of different serologic assays and strategies determining anti-tTG IgA, anti-DGP IgG and/or total IgA (to detect IgA deficiency) for CD diagnosis. Additionally a new tTG/DGP screening assay simultaneously measuring IgA and IgG was evaluated.

Summary:
To judge the best strategy for CD diagnosis likelihood ratios (LRs) were calculated. Because LRs are independent from the prevalence they overcome the problem of comparing studies in populations with a different prevalence of CD.
The results show a comparable performance of the tTG IgA and DGP IgG assays, also between the two different manufacturers used. Highest sensitivity was reached by using the combination of tTG IgA and DGP IgG. This combination also gives the highest LR (≥215) when double positive and the lowest LR (≤0.12) when double negative.
The tTG/DGP screening assay shows a higher sensitivity but lower LRs than the strategies using separate tTG and DGP determination.

Conclusions:
The combination of tTG IgA and DGP IgG reveals to be the best strategy for CD diagnosis as it performed best in all patients.
The new CD screening assay shows good sensitivity but low clinical guidance because neither antibody nor isotype can be determined directly by a positive result.

Comment:
According to this study we recommend the use of separate tTG IgA and DGP IgG assays as the best combination and best serologic strategy for CD diagnosis.
This study also shows that the calculation of LRs is very helpful in the comparison of different studies, strategies and assay performances.

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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.