Variability of anti-human transglutaminase testing in celiac disease across Mediterranean countries
Abstract
AIM
To verify the precision and accuracy of transglutaminase
antibodies (TGA) assays across Mediterranean countries.
METHODS
This study involved 8 referral centres for celiac disease
(CD) in 7 Mediterranean countries. A central laboratory
prepared 8 kits of 7 blinded and randomized serum
samples, with a titrated amount of Human TGA IgA.
Each sample was analysed three times on three
different days, with each centre running a total of 21
tests. The results were included in a blindly coded
report form, which was sent to the coordinator centre.
The coordinator estimated the mean coefficient of
Variation (CoVar = σ/μ), the mean accuracy (Accur
= Vobserved - Vreal) and the mean percent variation
(Var% = [(Vobserved - Vreal)/Vreal] × 100).
RESULTS
The analysis showed that 79.17% of the mean variation
fell between -25% and +25% of the expected value,
with the accuracy and precision progressively increasing
with higher titres of TGA. From values 1.25 times
greater than the normal cut-off, the measurements
were highly reliable.
CONCLUSION
TGA estimation is a crucial step for the diagnosis of
CD; given its accuracy and precision, clinicians could be
confident in establishing a diagnosis.