AGBL2 and rheumatoid arthritis: The second antibody detectable if individuals were positive for anti-CCP2 antibodies was IgM-RF, and positivity for both antibodies yielded 100 % probability of detecting pre-symptomatic individuals who would develop RA within 3 years, with a sensitivity of 68.3 %, a specificity if 93.3 %, PPV of 87.7 % and NPV of 80.9 %.