PRTN3 and rheumatoid arthritis: In order to exclude that this additional effect of TRA2B antibodies was due to the thresholding of cTRA2B antibodies, the analysis was repeated with the absolute measures of cTRA2B concentrations: similarly, a combination of cTRA2B antibodies with ACPA or cTRA2B antibodies with ACPA and RF significantly improved prediction of RA (p = 0.008 and 0.03, respectively).