As with established RA, a strong relationship with log CXCL13 levels and seropositivity had already been seen at the inclusion visit (P < 0.0001) (Figure 3A) with a geometric mean (95% CI) of 50.1 pg/ml (35.0 to 78.0) in seronegatives and 323.6 pg/ml (223.9 to 477.5) in seropositives. Here, CXCL13 is linked to rheumatoid arthritis.