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The Predictive Value of Anti-Cyclic Citrullinated Peptide Antibodies in Early Arthritis
LOUISE M.A. JANSEN, DIRKJAN VAN SCHAARDENBURG, IRENE E. VAN DER HORST-BRUINSMA, ROB J. VAN DE STADT, MARGRET H.M.T. DE KONING, and BEN A.C. DIJKMANS
ABSTRACT.
Methods. Consecutive new patients with peripheral arthritis of > 2 joints and < 2 years of symptom duration, referred between 1995 and 1999 were studied. Excluded were patients with bacterial, psoriatic, crystal-induced arthritis or spondyloarthropathy. Optimal cut-off values for serum IgM-rheumatoid factor (RF) and anti-CCP were deduced from receiver operating characteristics curves. At 2 year followup, progressive erosive disease was defined as: radiographic progression > 5 (Sharp-van der Heijde units) and low functional capacity as a Health Assessment Questionnaire score > 1. For the statistical analysis, a logistic regression model was used. Results. A total of 282 patients [68% female, median age 56 yrs (18–83)] were included. Thirty-two percent of the patients were positive for anti-CCP at baseline. Anti-CCP correlated significantly (p < 0.001) with a progressive erosive disease after 2 years, but not with a low functional capacity. The combination of a positive anti-CCP status and radiographic damage at baseline could predict the radiographic progression with a sensitivity, specificity, and accuracy of 78%, 82%, and 81%, respectively. The positive predictive value (PPV) for radiographic progressive disease was 63%, while the negative predictive value (NPV) was 90%. The accuracy of the model decreased from 81 to 76% after leaving out anti-CCP from the model. In a subgroup of 178 IgM-RF negative patients, the PPV for radiographic progressive disease was 40%, while the NPV was 95%. Conclusion. Anti-CCP positivity has a small additional value above the conventional prognostic variables for progressive erosive disease in a cohort of patients with early inflammatory oligo- and polyarthritis. The prognostic value of anti-CCP lies mainly in its ability to predict mild disease. This effect is accentuated in the subgroup of IgM-RF negative patients. (J Rheumatol 2003;30:1691-5) Key Indexing Terms:
ANTIBODIES
From the Department of Rheumatology, Vrije Universiteit Medical Centre, and the Jan van Breemen Instituut, Amsterdam, The Netherlands. L.M.A. Jansen, PhD student; Dirkjan van Schaardenburg, MD, PhD, Jan van Breemen Instituut; I.E. van der Horst-Bruinsma, MD, PhD, Department of Rheumatology, Vrije Universiteit Medical Centre; R.J. van de Stadt, PhD; M.H.M.T. de Koning, Technician; Jan van Breemen Instituut; B.A.C. Dijkmans, MD, PhD, Department of Rheumatology, Vrije Universiteit Medical Centre, Amsterdam, The Netherlands. Address reprint requests to Dr. B.A.C. Dijkmans, Department of Rheumatology, Vrije Universiteit Medical Centre, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands. Submitted May 30, 2002; revision accepted January 30, 2003. |