Ratio of agalactosylated to monogalactosylated N-glycans in serum immunoglobulin (sIgG0/G1) is elevated at baseline and improves with treatment. Data show sG0/G1 from baseline and follow-up visits in both cohorts. All rheumatoid arthritis time points P < 0.001 vs healthy controls. P-values were derived from paired t-tests (*P < 0.05; **P = 0.01). Paired data available for Autoimmune Biomarkers Collaborative Network were n = 75 vs 3 months; Nested I, n = 61 vs 2 weeks and n = 48 vs 3 months.