CLINICAL HETEROGENEITY OF RHEUMATOID-ARTHRITIS AND THE ANTIPERINUCLEAR FACTOR

Objective. To assess the diagnostic and prognostic power of antiperinu clear factor (APF) and to identify a specific pattern of rheumatoid ar thritis (RA) of different evolution and prognosis. Methods. One hundre d and fifty-nine sera from patients with RA, 280 sera from patients wi th other rheumatic diseases and 204 sera from healthy subjects were ex amined for APF. Results. Sensitivity and specificity of the test were, respectively, 0.82 and 0.99 when 1:80 serum dilution was considered p ositive but 0.84 and 0.92 when tested at the currently used 1:5 serum dilution. According to the data obtained from APF and rheumatoid facto r (RF) testing, patients with RA were subdivided in 4 groups. Clinical and demographic features for each group were analyzed. RF+ and/or APF + patients showed a common pattern of disease, whereas RF-/APF- patien ts showed fewer extraarticular manifestations (p < 0.02) including Sjo gren's syndrome (p < 0.04) and an unusual onset of the disease charact erized by an involvement of large joints (p < 0.0001). Higher titer of APF was detected at the onset of the disease than in longstanding RA (p < 0.02). Conclusions. APF is a valuable diagnostic tool and a usefu l additional marker for RA. 1:80 serum dilution allows more specificit y without substantial loss of sensitivity. A specific pattern of RA ca n be identified on the basis of APF status.