To determine whether the significantly and differentially expressed circRNAs in the RA patients were relevant biomarkers for the disease activity of RA, we performed Spearman correlation tests to assess the correlation between RA clinical features (ESR, hs-CRP, RF, CCP, IGA, IGG, IGM, C3, C4, DAS28, VAS, SAS, SDS, etc.)and circRNA levels (hsa_circ_0001200, hsa_circ_0001566, hsa_circ_0003972 and hsa_circ_0008360). This evidence concerns the gene C4A and rheumatoid arthritis.