The combined detection of circulating RF_IgA, RF_IgG, and RF_IgM levels in peripheral blood predicted RA with an AUC of 0.88 (95% CI: 0.85-0.92, P < 0.001) (Figure 1(d)), with a sensitivity of 80.54% and a specificity of 81.45%. Here, CD40LG is linked to rheumatoid arthritis.