Notably, when comparing serum protein levels between patients with active RA with low and high cumulative GC doses using a lower cut-off value of 15 g (low/high, n = 23/25), which is the median of the values in the patient cohort, no difference was found after correction for multiple testing in the analysed serum protein levels, except in CCL20 (pcorr = 0.03, Supplementary Table S5). Here, CCL20 is linked to rheumatoid arthritis.