Pitfalls in Estimation of Celiac Disease Prevalence Using Serology: A Cross-Sectional Study

Abstract

Background:
Celiac disease (CD) is an auto-immune disorder. The prevalence of CD has been estimated mainly based on serological tests. The aim of this study was to evaluate the seroprevalence of celiac disease in the adult general population of Mashhad, northeast of Iran and pitfall of serology in epidemiological studies considering the importance of serology titer.

Materials and Methods:
1558 subjects aged 35 to 65 years and 1025 individuals aged between 15 to 35 years were selected randomly from multistage cluster sampling papulation for this cross sectional study. Anti-tissue transglutaminase (tTG)-IgA assay was performed by ELISA(Enzyme-Linked Immunosorbent Assay). The manufacture’s cut-off point of anti tTG was 20 IU/mL and the prevalence of positive serology was estimated based on being just above the upper limit of normal (20 IU/mL), twice or three times above the normal value at 40 and 60 IU/mL, respectively.

Results:
In both age group 35-65 year-old and 15 to 35 years adults, the prevalence of positive serology was 1.2% for anti-tTG level more than 60 IU/mL, which was three times of the kit references (95% CI: 0.7- 1.9) and (95% CI: 0.7-2.1), and based on our previous study in Mashhad if we consider the cut-off point as 76 IU/mL anti–tTG for mucosal atrophy, the prevalence of CD would be 0.69.

Conclusion:
Epidemiological data of CD is mainly based on serology and as these tests are to some extent non-specific at lower levels, the accuracy of the previous reported prevalence of CD in some studies are questionable and level of anti-tTG is important.