HLA-DRB1 and rheumatoid arthritis: Anti-Rgp IgG levels did not differ between CCP2-converters and non-converters (online supplemental figure 3C), or associate with arthritis progression, CCP2 IgG levels, RF, HLA-DRB1 SE, age, sex and smoking, when only Risk-RA individuals who remained CCP2-positive at study baseline were analysed (online supplemental table 3).