FBL and rheumatoid arthritis: Of all patients with very early RA, 53.3% were immunonegative for both anti-CCP antibodies and ACa-Fib, 6.5% were immunopositive for ACa-Fib, 17.4% were immunopositive for anti-CCP antibodies, and 22.8% were positive for both anti-CCP antibodies and ACa-Fib.