Table 1.

Sample demographics and clinical characteristics of JIA cohorts.

	HC PBMC	JIA PBMC	JIA SFMC
Number of participants, n	18	52	18
Gender, % female*	50.0	75.0	88.9
Age at sample in years, mean (range)*	28.6 (22–43)	7.4 (1–18)	11.0 (4–15)
Ethnicity, % Caucasian*	78.6	63.5	72.2
Disease duration:
Time since diagnosis, months (range)⋄	N/A	37.0 (2–125)	92.5 (19–158)
JIA subtype:
% RF- polyarticular	N/A	34.0	22.2
% Oligoarticular	N/A	66.0	77.8
Medication at time of sample:
Methotrexate, nΔ	N/A	Yes = 27 No = 20	Yes = 4 No = 7
Steroids, n∇	N/A	Yes = 24 No = 22	Yes = 4 No = 7
Biologics, n+	N/A	Yes = 4 No = 42	Yes = 1 No = 7
Clinical information at time of sample:
ANA, n#	N/A	Positive = 29 Negative = 12	Positive = 14 Negative = 2
AJC, mean (range)♦	N/A	1.28 (0–5)	1.82 (1–4)
cJADAS, mean (range)✦	N/A	5.63 (0–17.3)	6.50 (2.4–13.8)

AJC: active joint count; ANA: antinuclear antibodies (positive classified as titre ≥ 1:160); cJADAS: clinical Juvenile Arthritis Disease Activity Score (99); HC: healthy control; PBMC: peripheral blood mononuclear cells; RF: rheumatoid factor negative; SF: synovial fluid

^*22.2% of HC PBMC samples missing data;

^⋄7.7% of JIA PBMC samples missing data;

^Δ9.6% of JIA PBMC and 38.9% of JIA SFMC samples missing data;

^∇11.5% of JIA PBMC and 38.9% of JIA SFMC samples missing data;

⁺11.5% JIA PBMC and 55.6% of JIA SFMC samples missing data;

^#21.1% of JIA PBMC and 11.1% of JIA SFMC samples missing data;

^♦11.5% of JIA PBMC and 38.9% of JIA SFMC samples missing data;✦ 23.1% of JIA PBMC and 55.6% of JIA SFMC samples missing data.