PT  - JOURNAL ARTICLE
AU  - V P K Nell
AU  - K P Machold
AU  - T A Stamm
AU  - G Eberl
AU  - H Heinzl
AU  - M Uffmann
AU  - J S Smolen
AU  - G Steiner
TI  - Autoantibody profiling as early diagnostic and prognostic tool for rheumatoid arthritis
AID  - 10.1136/ard.2005.035691
DP  - 2005 Dec 01
TA  - Annals of the Rheumatic Diseases
PG  - 1731--1736
VI  - 64
IP  - 12
4099  - http://ard.bmj.com/content/64/12/1731.short
4100  - http://ard.bmj.com/content/64/12/1731.full
SO  - Ann Rheum Dis2005 Dec 01; 64
AB  - Background: Early treatment prevents progression of joint damage in rheumatoid arthritis (RA), but diagnosis in early disease is impeded by lack of appropriate diagnostic criteria.Objective: To study the value of rheumatoid factor (RF), anti-cyclic citrullinated peptide autoantibodies (anti-CCP), and anti-RA33 autoantibodies for diagnosis of RA and prediction of outcome in patients with very early arthritis.Methods: The prospective follow up inception cohort included 200 patients with very early (<3 months) inflammatory joint disease. Autoantibodies were measured at baseline and analysed in a tree based model which aimed at determining the added diagnostic value of testing for anti-CCP and anti-RA33 as compared with RF alone.Results: RA was diagnosed in 102 patients, while 98 developed other inflammatory arthropathies. Receiver operator curve analysis showed an optimum cut off level for RF at 50 U/ml, above which anti-CCP and anti-RA33 had no additional diagnostic value. Remarkably, RF ⩾50 U/ml and anti-CCP showed similar sensitivity and high specificity for RA, but overlapped considerably. Anti-RA33 was less specific and did not correlate with RF or anti-CCP. Among patients with RA, 72% showed at least one of these three autoantibodies, compared with 15% of non-RA patients. RF ⩾50 U/ml and anti-CCP were predictors of erosive disease, whereas anti-RA33 was associated with mild disease.Conclusions: Stepwise autoantibody testing in early inflammatory joint disease, starting with RF, followed by anti-CCP (in patients with RF <50 U/ml), and finally anti-RA33, should be used as a sensitive and effective strategy for distinguishing patients with RA at high risk for poor outcome.