Can tissue transglutaminase antibody titers replace small-bowel biopsy to diagnose celiac disease in select pediatric populations?

OBJECTIVES: The use of screening tests for celiac disease has increased the number of patients referred for evaluation. We proposed that the subgroup of patients with very high tissue transglutaminase antibody (TTG) titers is positive for celiac disease and a small-bowel biopsy is not necessary to make the diagnosis. A gluten-free diet should be attempted and, if the patient's symptoms do not improve, then a biopsy should be performed to confirm the diagnosis.
METHODS: A chart review of data for 103 patients who underwent both TTG testing and a small-bowel biopsy was performed. We examined the impact of using TTG values of >100 U and <20 U as cutoff values and suggested performing biopsies for patients with TTG values of 20 to 100 U, as is current practice.
RESULTS: Fifty-eight of 103 patients demonstrated positive biopsy results. Forty-nine of 103 patients had TTG levels of >100 U, with 48 of 49 exhibiting positive biopsy results. Only 7 of 16 patients with TTG values of 20 to 100 U exhibited positive biopsy results. Three patients with TTG levels of <20 U had positive biopsies; 2 were IgA negative and 1 had a duodenal ulcer. With the cutoff values of >100 U and <20 U with known IgA status, the sensitivity was 0.980 (48 of 49 cases) and the specificity was 0.972 (35 of 36 cases). An incremental cost analysis found that this proposal could potentially decrease the costs of investigation and diagnosis by almost 30%.
CONCLUSIONS: When the cutoff values were changed to >100 and <20 U and IgA levels were verified, the sensitivity and specificity were very high. Patients with mid-range TTG values (20-100 U) or values of <20 U with negative IgA status should continue to undergo biopsies for diagnosis of celiac disease.