ESR1 and rheumatoid arthritis: However, considering inflammatory markers, ESR plasma levels were significantly higher in naïve Abneg RA patients (44.00 ± 25.40 mm/first hour) than MTX-IR Abneg RA patients (29.60 ± 36.94 mm/first hour; p = 0.03), whereas no differences were found for CRP plasma levels comparing naïve and MTX-IR PsA subgroups (Table 1).