Analytical and clinical comparison of anti-CCP assays with rheumatoid factor for the diagnosis of rheumatoid arthritis.

INTRODUCTION

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease characterized by chronic joint inflammation and extra-articular manifestations, eventually leading to permanent disability without early therapeutic interventions.

METHODS

The analytical and clinical performance of an electrochemiluminescent immunoassay (ECLIA) (Roche Diagnostics, Indianapolis, IN) were determined for cyclic citrullinated peptide antibodies (anti-CCP) in the diagnostic assessment of rheumatoid arthritis compared to a plate-based anti-CCP enzyme immunoassay (EIA) (Inova Diagnostics, Inc.).

RESULTS

Imprecision studies on the automated Roche ECLIA demonstrated intra-assay CV's of <3% and inter-assay CV's of <7%. The Inova EIA had intra-assay CV's of <15% and inter-assay CV's of <12%. The limit of quantitation of both assays was acceptable, and both assays showed similar linearity within the manufacturer's defined reportable ranges. Overall, analytical concordance was 62%, with 95.2% positive and 53.2% negative concordance. The clinical specificity in a normal population (n=91) was 98.9% and 100% for Roche ECLIA and Inova EIA, respectively. The clinical specificity in a connective tissue disease population (n=98) was 91.9% (95%CI, 86.0 to 96.5%) and 88.8% (95% CI, 81.0 to 93.6%) for Roche ECLIA and Inova EIA, respectively.

CONCLUSION

The Roche ECLIA demonstrated similar analytical performance, although with improved intra-assay precision, in comparison to the Inova EIA. The two methods also demonstrated similar clinical sensitivity and specificity. The Roche automated immunoassay is a viable alternative to the plate-based EIAs with the advantage of being performed on an automated platform.