Table 1 Patients’ characteristics (absolute number of patients, percentages, descriptive statistics as reported in BIKER; comparison between the three cohorts weighted by an inverse probability of treatment)

Female, n (%)

332 (79.2%)

192 (81.4%)

51 (68.8%)

0.96 (0.57; 1.62); 0.88

0.63 (0.45; 0.89); 0.03

0.58 (0.48; 0.98); 0.04

Age at baseline, years, mean ± SD

10.5 ± 4.4

11.8 ± 4.0

12.9 ± 3.6

0.63 (−0.31; 1.57); 0.19

1.65 (−0.67; 3.96); 0.16

1.02 (−1.31; 3.34); 0.39

 Median (IQR)

11.1 (7.1–13.9)

12.7 (8.7– 15.0)

13.5 (11.2– 15.9)

Disease duration at treatment start, mean ± SD

3.6 ± 3.3

5.8 ± 4.0

6.1 ± 3.5

0.40 (−0.17; 0.98); 0.17

1.13 (−0.05; 2.02); 0.07

0.73 (−0.21; 1.66); 0.13

 Median (IQR)

2.6 (1.1–5.1)

4.9 (2.4–8.4)

5.8 (2.9–8.8)

 RF+ PA

37 (8.8%)

23 (9.7%)

9 (12.2%)

1.45 (0.74; 2.83); 0.28

0.95 (0.60; 1.49); 0.81

2.18 (0.48; 9.85); 0.31

 RF- PA

224 (53.5%)

128 (54.2%)

47 (63.5%)

(ref)

(ref)

(ref)

 ExOA

158 (37.7%)

85 (36.0%)

18 (24.3%)

3.17 (0.74; 13.60); 0.12

0.71 (0.22; 2.27); 0.57

0.75 (0.24; 2.41); 0.63

First biologic used

400 (95.5%)

110 (46.6%)

14 (18.9%)

0.54 (0.28; 1.03); 0.06

0.44 (0.16; 1.18); 0.10

0.81 (0.34; 1.96); 0.65

Co-med corticosteroids, n (%)

134 (32.0)

60 (25.4)

26 (35.1)

1.38 (0.96; 1.97)

1.15 (0.69; 1.94)

1.59 (091; 2.78)

Co-med MTX, n (%)

302 (72.1)

127 (53.8)

34 (45.9)

1.20 (0.76; 1.88); 0.44

0.76 (0.28; 2.06); 0.59

0.64 (0.24; 1.70); 0.37

JADAS10 (0–40), mean ± SD

13.8 ± 7.1

12.1 ± 7.6

15.1 ± 7.4

−0.41 (−2.30; 1.48); 0.67

−0.53 (−4.22; 3.17); 0.78

−0.12 (−3.84; 3.60); 0.95

 Median (IQR)

13.6 (8.8–19.0)

11.7 (6.1–17.5)

14.8 (9.2–20.1)

CHAQ-DI (0–3), mean ± SD

0.59 ± 0.60

0.43 ± 0.58

0.63 ± 0.55

−0.04 (−0.19; 0.12); 0.64

−0.10 (−0.30; 0.11); 0.35

−0.06 (−0.29; 0.17); 0.60

 Median (IQR)

0.38 (0.13–0.88)

0.13 (0–0.623)

0.63 (0.19-1.0)

Uveitis before start of biologic

23 (5.5%)

59 (25%)

0

3.41 (3.21; 4.45); 0.03

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