A comparison of the diagnostic accuracy and prognostic value of the first and second anti-cyclic citrullinated peptides (CCP1 and CCP2) autoantibody tests for rheumatoid arthritis
- 1Department of Rheumatology, Leiden University Medical Centre Leiden, The Netherlands
- 2Department of Internal Medicine, Rijnland Hospital, Leiderdorp, The Netherlands
- 3Department of Rheumatology, Rijnstate Hospital, Arnhem, The Netherlands
- Correspondence to:
Professor Dr T W J Huizinga
Department of Rheumatology, Leiden University Medical Centre, PO Box 9600, 2300 RC, Leiden, The Netherlands;
- Accepted 21 March 2005
- Published Online First 30 March 2005
Objectives: To compare the diagnostic performance and prognostic value of the anti-cyclic citrullinated peptide (CCP1) and anti-CCP2 autoantibody tests in a clinical setting.
Methods: Anti-CCP1 and anti-CCP2 antibody tests were performed on the same serum samples obtained from 467 patients with early arthritis from the Leiden Arthritis Cohort. The sensitivity, specificity, positive predictive value, and negative predictive value for discriminating between rheumatoid arthritis (RA) and non-RA at 1 year’s follow up were calculated for both tests. Results were graphically presented using receiver operating characteristic curves. Progression of radiological joint damage was assessed over 4 years in patients with RA and used to assess the prognostics values of the CCP tests.
Results: At a similar specificity the CCP2 test had a higher sensitivity than the CCP1 test. Both tests identified a subgroup of patients with RA with an increased rate of joint damage progression. The anti-CCP2 test identified more patients with an increased rate of joint damage progression than the anti-CCP1 test, and in multiple regression analysis CCP2 was the better predictor of joint damage.
Conclusions: The CCP2 test had better diagnostic and prognostic ability than the CCP1 test.
- AUC, area under the curve
- CCP, cyclic citrullinated peptide
- CI, confidence interval
- ELISA, enzyme linked immunosorbent assay
- ROC, receiver operating characteristic
- RA, rheumatoid arthritis
The authors declare no competing interests.
As stated in “Patients and methods”: In 1993, after approval of the institutional review board, the Early Arthritis Cohort was started at the Department of Rheumatology of the Leiden University Medical Centre, Leiden, The Netherlands.
Published Online First 30 March 2005