Celiac.com 03/11/2010 - Many people are confused about which tests provide the most accurate results for a celiac disease diagnosis. In a recent study by a team at the Department of Gastroenternology and Internal Medicine, St. Orsola-Malpigihi Hospital, University of Bologna, Bologna, Italy, researchers evaluated current testing methods, and made some conclusions about celiac testing that may shed light on the subject for those of us overwhelmed by current conflicting information.
Duodenal biopsy is considered to be the universal 'gold standard' for celiac diagnosis. However, in recent years the importance of serological testing has been been emphasized as a reliable marker for antibodies as well. The tTG antibodies of IgA class are currently recognized to be the most effective test for celiac screening, resulting in up to 95% accuracy. Although, a new serological test, DGP, is now being investigated as a more reliable alternative to tTG.
A study was devised to compare the effectiveness of DGP antibodies with that of tTG antibodies, and used a meta-analysis of eleven studies that were published between 1998 and 2008. The study analyzed the results of 937 patients with untreated celiac, and 1,328 control subjects. The analysis of the eleven studies showed that IgA tTG antibodies revealed a higher likelihood ratio (LR) than IgA DGP antibodies, and IgA tTG antibodies exhibited a lower LR than IgA DGP antibodies. The data between the two antibody tests validates that IgA tTG continues to display the most accurate diagnostic tests for a positive celiac diagnosis, as well as for excluding a negative celiac diagnosis. However IgG DGP antibody tests were shown to be more effective at identifying 'false negatives' and had more success in determining celiac in patients that had IgA deficiency, and in children under two years old.
The results of these tests clearly demonstrate that IgA DGP does not offer any advantages to the IgA tTG antibodies, and is actually less accurate and more expensive. However, IgG DGP antibodies present an invaluable tool in screening for celiac disease in cases where IgA tTG tests fail. Eventually, a new antibody screening will hopefully be designed which combines IgA tTG and IgG DGP, and reduces the number of tests currently used in celiac screening. However, intestinal biopsy is always required to confirm the presence of celiac disease no matter what serological tests are involved.Source:http://www.ncbi.nlm.nih.gov/pubmed/20136587