CCN2 and rheumatoid arthritis: Furthermore, we confirmed a similar increase in CTGF levels in the serum samples of 98 patients with RA and identified the diagnostic value of serum CTGF with sensitivity, specificity, and AUC of ROC curve at 0.86, 0.92, and 0.92, respectively, at the optimal cutoff value of 88.66 pg/ml (11).