Table 1.

Characteristics of the study subjects^a

Variable	SpA group (n = 122)	AS group (n = 95)	nrSpA group (n = 27)	Control group (n = 75)
Male:female ratio (% male)	90:32 (73.8)	73:22 (76.8)	17:10 (63.0)	42:33 (56.0)
Age, years	33.8 [17.3 to 71.6]	35.7 [17.3 to 71.6]	27.0 [18.8 to 44.8]	30.3 [17.7 to 63.8]
Symptom duration, years	7.0 [0.3 to 41.0]	11.0 [0.3 to 41.0]	1.2 [0.3 to 5.0]	N/A
HLA-B27-positive, n (%)b	105/120 (87.5)	81/93 (87.1)	24/27 (88.9)	N/A
BASDAI, NRS range 0 to 10	4.4 [0.4 to 9.0]	4.6 [0.4 to 9.0]	3.9 [0.8 to 6.3]	N/A
BASFI, NRS range 0 to 10	2.9 [0 to 8.2]	3.2 [0 to 7.8]	2.1 [0 to 8.2]	N/A
BASMI, NRS range 0 to 10	1.0 [0 to 8.0]	1.0 [0 to 8.0]	0 [0 to 4.0]	N/A
CRP level, mg/L	5.0 [0 to 150.0]	5.0 [0 to 57.0]	3.0 [0 to 150.0]	N/A
ESR (mm/hour)	12.5 [1.0 to 72.0]	14.0 [2.0 to 69.0]	8.5 [1.0 to 72.0]	N/A

^aAS = ankylosing spondylitis; BASDAI = Bath Ankylosing Spondylitis Disease Activity Index [23]; BASFI = Bath Ankylosing Spondylitis Functional Index [24]; BASMI = Bath Ankylosing Spondylitis Metrology Index [25]; CRP = C-reactive protein, reference range ≤5 mg/L; ESR = erythrocyte sedimentation rate; HLA-B27 = human leukocyte antigen B27; N/A = not applicable; NRS = numeric rating scale; nrSpA = nonradiographic axial spondyloarthritis; SpA = spondyloarthritis. ^bHLA-B27 was not tested in two patients in the AS group. Values for the continuous demographic and clinical variables are medians [IQR] unless otherwise stated.