Efficacy of three ELISA measurements of anti-cyclic citrullinated peptide antibodies in the early diagnosis of rheumatoid arthritis.

Department of Biotechnology, Empresa Pública Hospital de Poniente de Almería, El Ejido, Almería, Spain.
Clinical Chemistry and Laboratory Medicine (Impact Factor: 3.01). 02/2005; 43(11):1234-9. DOI: 10.1515/CCLM.2005.214
Source: PubMed

ABSTRACT The objective of the present study was to determine the efficacy of anti-cyclic citrullinated peptide (anti-CCP) antibody detection in the early diagnosis of rheumatoid arthritis (RA), as well as to compare three commercially available enzyme-linked immunosorbent assay (ELISA) kits used to detect such antibodies. We analysed the presence of anti-CCP antibodies in the sera of 78 patients who had been newly referred from primary healthcare centres to the Early Polyarthritis Unit. We also included in the study a group of 50 healthy controls. None of the patients had previously received treatment for the disease. After 1-year follow-up, the diagnosis of RA was confirmed in 53 of these patients. The ELISA kits under study were IMMUNOSCAN RA (Euro-Diagnostica AB), QUANTA Lite CCP IgG ELISA (INOVA Diagnostic) and DIA-STAT Anti-CCP (Axis-Shield Diagnostics); the sensitivity obtained was 52.8%, 58.5% and 52.8%, respectively, with 100% specificity for all three kits. Anti-CCP antibodies detected the presence of RA in 26% of patients without positive rheumatoid factor (RF). The sum of anti-CCP antibodies or the presence of RF gave a sensitivity of up to 67%, with specificity ranging between 94 and 97%. Anti-CCP antibodies show high specificity for the diagnosis of RA. The three ELISAs analysed offer the same degree of diagnostic accuracy.

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    ABSTRACT: Autoantibodies against cyclic citrullinated peptide (anti-CCP) are considered to be a sensitive and specific marker for rheumatoid arthritis (RA). This study evaluated the diagnostic and analytical performances of the automated anti-CCP assay. Sera from 80 patients with established RA, 65 from other rheumatic diseases (non-RA) and 55 from healthy controls were studied using second generation anti-CCP. Rheumatoid factor (RF) was also assayed in each sample, and the results were compared to the anti-CCP findings. Serum pools were used to determine the precision and linearity. At a cut-off of 7.4 U/ml for anti-CCP, the sensitivity and specificity for RA were 65% and 98% respectively. RF had a sensitivity of 58% and a lower specificity of 93% than anti-CCP. The high specificity of the assay suggests that anti-CCP is useful in the diagnosis of rheumatoid arthritis and in our cohort of study population anti-CCP exhibits a better diagnostic value than RF. A considerable proportion (28%) of RF-negative RA patients were anti-CCP positive. Based on analytical performance of the assay, we conclude that full automation and high throughput features of AxSYM makes it an ideal platform for routine testing of anti-CCP.
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