Abstract
Background: Currently, a new rapid and fully automated electrochemiluminescence immunoassay for the determination of TSH receptor (TSHR) autoantibodies (TRAb) based on the inhibition of binding of a human thyroid-stimulating monoclonal antibody (M22) has been developed.
Aims: The aim of this study was to evaluate this assay system in clinical routine based on an international multicenter trial.
Methods: 508 Graves’ disease (GD) patients, 142 autoimmune thyroiditis patients, 107 subacute thyroiditis patients and 109 patients with non-autoimmune nodular goiter were retrospectively evaluated. Based on these results an receiver operating characteristics analysis (ROC plot) was performed to calculate the threshold for positivity. Moreover, results were compared with other established assay systems.
Results: ROC plot analysis revealed an area under curve (AUC) of 0.99 (0.95% CI: 0.99 – 1.0) indicating a high sensitivity and specificity of the assay. The highest sensitivity (99%) and specificity (99%) was seen at a cut-off level 1.75 IU/L. The calculated positive predictive value (PPV) at this cut-off level was 95%, whereas the negative predicitive value (NPV) was estimated as 100%. Applying the ROC plot-derived cut-off of 1.75 IU/L we found a sensitivity for TRAb positivity within the GD group of 88% which is in accordance to the sum of different routine assays with a sensitivity of 87%. Importantly, within the group of newly-diagnosed GD patients the sensitivity of the automated TRAb assay was 97% and of the sum of routine assays 94% indicating an excellent analytical performance of the new assay format. Detailled comparison of the automated and the sum of manual assay formats revealed a near identical specificity in all patient groups.
Conclusion: Our results demonstrate that this new assay system has a high senstivity for detecting GD and for discriminating other thyroid diseases and may, therefore, represent the future technology for a rapid and fully-automated TRAb detection.