Table 1: Patient's characteristics at the moment of dosing biologic drug level.

Biologic agentCurrent biologic treatment, duration, and meanDAS28 baseline, meanSDAI baseline, meancsDMARD associated, no (%)ACPA positive, no (%)RF positive, no (%)

RTX
 Group A 15 (60%)14 (56%)16 (64%)
 Group B 8 (32%)4 (16%)7 (28%)
0.2940.6780.8450.6670.0210.049
IFX
 Group A 6 (30%)4 (20%)7 (35%)
 Group B 6 (30%)3 (15%)4 (20%)
0.3790.0030.0260.5820.5150.064
ETN
 Group A 10 (55.55%)11 (61.11%)12 (66.67%)
 Group B 3 (16.67%)2 (11.11%)2 (11.11%)
0.6790.2590.6390.2390.8140.612
ADL
 Group A 7 (77.78%)4 (44.44%)6 (66.67%)
 Group B363.5432.91 (11.11%)1 (11.11%)1 (11.11%)
0.7000.9020.0090.7080.4950.571

Differences between patient's baseline characteristics were tested by Student’s -test or chi-square test.
RTX: rituximab; IFX: infliximab; ETN: etanercept; ADL: adalimumab.
Group A: detectable drug level; Group B: undetectable drug level.
csDMARD: conventional synthetic disease modifying antirheumatic drug; ACPA: anticitrullinated peptides antibodies status; RF: rheumatoid factor status.