Table 1 Clinical characteristics of RA and JIA patients and heathy controls

Sex ratio (Female/Male)

3.63 (842/232)

3.47 (1314/378)

0.17

4.56 (178/39)

4.72 (312/66)

0.89

Age (years)

41.7 ± 11.6

39.6 ± 13.2

0.75

6.3 ± 3.1

6.7 ± 2.5

0.75

Onset age, years

49.5 ± 7.9

–

–

7.5 ± 4.9

–

–

Bone erosions n (%)

421 (39.1%)

–

–

46 (21.3%)

–

–

Shared epitope

467 (43.5%)

–

–

79 (36.4%)

–

–

DAS28

4.7 ± 1.3

–

–

3.4 ± 1.1

–

–

ESR (mm/h) (0–10 mm/h)

33.2 ± 12.5

4.5 ± 2.2

<0.001

34.5 ± 19.3

4.3 ± 2.4

<0.001

CRP (mg/l) (0.8–8 mg/l)

25.8 ± 12.2

4.9 ± 1.3

<0.001

19.3 ± 37.5

3.77 ± 1.4

<0.001

IgA mg/mL (0.71–3.35 mg/mL)

12.2 ± 2.7

2.88 ± 1.4

<0.001

10.2 ± 2.4

2.59 ± 1.7

<0.001

IgG mg/mL (7.6–16.6 mg/mL)

45.7 ± 5.4

10.3 ± 4.1

<0.001

29.6 ± 5.1

9.7 ± 1.3

<0.001

IgM mg/mL (0.48–2.12 mg/mL)

6.6 ± 1.3

1.78 ± 2.1

<0.001

5.4 ± 1.7

1.88 ± 1.02

<0.001

RF⁺, %

826 (76.9%)

0 (0%)

37 (16.9%)

0 (0%)

CCP⁺, %

766 (71.3%)

0 (0%)

33 (15.4%)

0 (0%)