The results showed that, in contrast with urine sCD14 levels, serum sCD14 levels measured by the FRENDTM-CD14 system correlated with ESR, serum CRP, and the DAS28ESR, indicating that they reflect RA disease activity well; the correlation coefficients were 0.494 for ESR (p < 0.001), 0.323 for CRP (p < 0.001), and 0.442 for the DAS28ESR (p < 0.001) (Figure 2A–C). This evidence concerns the gene ESR1 and rheumatoid arthritis.