Screening for coeliac disease in rural Australia

Anti-tissue transglutaminase (anti-tTG) antibody assays were used to screen people in the rural Western Australian community of Busselton for coeliac disease.  The study had the dual aim of, determining the prevalence of coeliac disease in the community: and whether the anti-tTG assay is appropriate for population screening for coeliac disease. 

Samples for this study were analysed retrospectively from those taken in 1994-1995 from 3011 subjects in the Busselton Health Study follow-up. Assays for IgA and IgG anti-tTG antibodies were performed, and positive or equivocal samples were retested with a different commercial anti-tTG assay. Where the subjects from the Busselton Health Study were still able to be contacted, those with one or more positive assay results were interviewed, had serum collected for repeat anti-tTG assays and for HLA-DQ2 and HLA-DQ8 haplotyping and, if appropriate, gastroscopy and duodenal biopsy were performed. In unavailable subjects, HLA-DQ2 and -DQ8 haplotyping was performed on stored sera. Total serum IgA levels were assessed in subjects with initially negative assay results.

In 47 of 3011 serum samples (1.56%), at least one anti-tTG assay gave positive results: 31 of the subjects who provided these sera were available for further testing, and 21 of these subjects underwent a gastroscopy. Seventeen subjects (0.56%) were diagnosed with definite coeliac disease.

In 12 subjects, coeliac disease status was considered equivocal, with one or more positive anti-tTG assay results and an HLA haplotype consistent with coeliac disease. If these subjects were regarded as having coeliac disease, the prevalence of CD would be 0.96%.

The prevalence of coeliac disease in the rural population screened is at least 0.56% and may be closer to 1%. The use of a single anti-tTG assay for coeliac disease screening produced many discrepancies.  However, the use of different assays may improve the reliability and decrease the need for confirmatory gastroscopy and duodenal biopsy.

Reference: Chin et al. 2009 Medical Journal of Australia. Vol 190(8) pp 429-32.