Table 1. Baseline characteristics of RA and non-RA groups.

	RA (n = 13)	Non-RA (n = 25)
		AS (n = 7)	BD (n = 5)	Gout (n = 13)
Age, mean ± SD years	44.2±10.7	35.4±10.7	41.6±12.5	45.9±7.9
Female, no. (%)	13 (100)	3 (42.9)	2 (40.0)	0 (0.0)
Disease duration, years	6.5±6.3	3.1±3.3	6.3±7.9	7.9±2.7
RF, no. of positive/tested (%)	13 (100)	0/5 (0.0)	1/3 (33.3)	0/7 (0.0)
ACPA, no. of positive/tested (%)	3/3 (100)	n.a.	n.a.	n.a.
FANA, no. of positive/tested (%)	n.a.	0/3 (0.0)	0/2 (0.0)	0/2 (0.0)
HLA-B27, no. of positive/tested (%)	n.a.	6/6 (100.0)	n.a.	n.a.
Fulfillment of criteria, no. of positive/tested (%)
1987 ACR	12/13 (92.3)	n.a.	n.a.	n.a.
1984 modified NY	n.a.	7/7 (100.0)	1/5 (20.0)	n.a.
2010 ACR/EULAR	13/13 (100.0)	n.a.	n.a.	n.a.
ASAS axial	n.a.	7/7 (100.0)	n.a.	n.a.
Previous NSAID, no. of positive/tested (%)	12/13 (92.3)	22/25 (88.0)	2/5 (40.0)	13/13 (100.0)
Previous intraarticular steroid injection, no. or no. of positive/tested (%)	10/13 (76.9)	4/7 (57.1)	3/5 (60.0)	3/13 (23.1)

ACPA, anti-CCP antibody; ACR, The American College of Rheumatology classification criteria of RA; ACR/EULAR, The American College of Rheumatology/European League Against Rheumatism classification criteria for RA; AS, ankylosing spondylitis; ASAS axial, Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis; BD, Behçet's disease; FANA, fluorescent anti-nuclear antibody; HLA-B27, human leukocyte antigen B27; modified NY, Modified New York criteria for the diagnosis of AS; n.a, not applicable; non-RA, non-rheumatoid arthritis including ankylosing spondylitis, Behçet's disease, and gout; Previous NSAID, previously use of non-steroidal anti-inflammatory drug; RA, rheumatoid arthritis; RF, rheumatoid factor.