Performance analysis of the ARCHITECT anti-cyclic citrullinated peptide antibody in the diagnosis of rheumatoid arthritis.

BACKGROUND Anti-cyclic citrullinated peptide (CCP) antibody is emerging as an important diagnostic marker for rheumatoid arthritis (RA). We evaluated the analytical and diagnostic performance of the ARCHITECT anti-CCP (Abbott Diagnostics), a new fully automated chemiluminescent microparticle immunoassay. METHODS Serum samples from 69 patients with RA and 86 non-RA patients were used to evaluate the performance of the ARCHITECT anti-CCP assay, and the results were compared with those of EliA CCP (Phadia). The optimal cut-off value was calculated using receiver operating characteristic (ROC) curve analysis. RESULTS Within-run and total imprecision (%CV) of the ARCHITECT anti-CCP were <6% and good linearity was observed over the claimed range. The areas under the ROC curves for the ARCHITECT anti-CCP and EliA CCP were 0.90 and 0.89, respectively. The sensitivity and specificity were 76.8% and 95.3% for the ARCHITECT anti-CCP and 78.3% and 95.3% for EliA CCP using the manufacturer's cut-off thresholds. Both assays showed sensitivity of 84.1% and specificity of 94.2% using the optimal cut-off values. CONCLUSIONS The analytical performance of the ARCHITECT anti-CCP was satisfactory and diagnostic performance was comparable to that of EliA CCP. The use of optimal cut-off thresholds can yield higher sensitivity with minimal loss of specificity.