Thrombotic Markers in Plasma as Predictors of Response in Rheumatoid Arthritis Patients Treated with Baricitinib – Pilot Observation

Both disease and treatment carry the risk of thrombotic events in patients with rheumatoid arthritis (RA). This pilot study aimed to assess changes in thrombotic markers in plasma and their potential role as predictors of response during early baricitinib treatment. The concentrations of antithrombin III (ATIII) activity, D-dimer (DD), fibrinogen, and homocysteine (HCY) were evaluated in RA subjects before and 3 months after the treatment. At baseline, the RA group had higher DD (1472.3 ± 349.2) and fibrinogen (410.4 ± 29.5) compared with healthy controls (HC; 450.3 ± 54.5; <i>p</i> = 0.0002 and 334.9 ± 19.2; <i>p</i> = 0.04, respectively). with no differences in ATIII and HCY. After 3 months, we observed a significant increase in HCY (10.7 ± 0.6 vs. 9.1 ± 0.5; <i>p</i> = 0.018) and ATIII (119.7 ± 2.7 <i>vs</i>. 110.4 ± 3.2; <i>p</i> = 0.004), the latter correlated negatively with disease activity score 28 (DAS28; <i>r</i> = -0686, <i>p</i> < 0.002). After 3 months of baricitinib therapy, the patients were divided into moderate responders (MR) and good responders (GR) groups according to EULAR criteria. At baseline, MR had higher DD (1639.2 ± 550.5 <i>vs</i>. 450.3 ± 54.5; <i>p</i> < 0.0001) and lower ATIII (105.3 ± 3.6 <i>vs</i>. 115.1 ± 2.7; <i>p</i> = 0.043) compared with HC. Thrombotic parameters in the first 3 months of baricitinib treatment were mostly in line with current findings concerning the RA population. Increased levels of DD together with low ATIII concentrations seem to predispose to a moderate response to baricitinib treatment.