Objectives: The efficacy of celiac disease (CD)-related antibodies in monitoring clinical outcome of patients remains unclear. Our aims were to determine dynamics of antibodies after diagnosis and to assess their performances in monitoring patients' long-term compliance with the gluten-free diet (GFD).
Methods: We prospectively estimated the performance of seven celiac disease-related antibody tests at diagnosis and at 1 year and more than 4 years after treatment initiation in 53 adults. The ability of antibodies to identify patients partially compliant to treatment was explored by the receiver operating characteristic curve analysis. The derived cut-off values ('compliance' cutoffs) were compared with cut-off values used for diagnosis ('diagnostic' cutoffs). The degree of compliance with the GFD was assessed using a standardized, multidisciplinary approach.
Results: Concentrations of all antibodies decreased significantly at 1 year after diagnosis. The decline continued for more than 4 years in strictly compliant patients (P<0.05-0.001). The gap between 'compliance' and 'diagnostic' cut-offs values was wider at 1 year than at more than 4 years. The predictability of partial compliance determined by the area under receiver operating characteristic curves was relevant for most tests examined at 1 year (areas ranging: 0.64-0.72) and more than 4 years (0.58-0.78). Immunoglobulin A antibodies to deamidated gliadin peptides and tissue transglutaminase had the best performance for monitoring long-term compliance.
Conclusion: Decreased concentrations of antibodies were significantly associated with the degree of compliance with the GFD. Immunoglobulin A antibodies to deamidated gliadin peptides and tissue transglutaminase had the best and more consistent performances. The serial measurement of antibody levels seems to be more reliable in monitoring compliance than the positive/negative expression of results.