TNF and rheumatoid arthritis: Methylation levels between RA (in the left of Figure 2B, median 3.42% [95% CI 2.42; 4.92]) versus non-RA patients (6.44% [4.83; 8.39]) were highly significant (p = 4.0 × 10−9), confirming that the TNF-qMSP assay has the inherent ability to discriminate between patients progressing to RA from other forms of IA.