MRI evidence of structural changes in the sacroiliac joints of patients with non-radiographic axial spondyloarthritis even in the absence of MRI inflammation

Table 1 Demographics and baseline disease characteristics according to the presence or absence of SIJ inflammation and structural lesions

	SPARCC SIJ BME ≥2 (N = 128)			SPARCC SIJ BME <2 (N = 55)			Total (N = 183)
	SSS >0 n = 69	SSS = 0 n = 59	P value	SSS >0 n = 7	SSS = 0 n = 48	P value	SSS >0 n = 76	SSS = 0 n = 107	P value
Age, years*	30.3 (6.8)	33.5 (7.7)	0.01	33.9 (11.9)	32.6 (8.5)	0.73	30.6 (7.3)	33.1 (8.0)	0.04
Male, n (%)^†	57 (82.6)	28 (47.5)	<0.001	3 (42.9)	22 (45.8)	1.0	60 (79.0)	50 (46.7)	<0.001
BMI, kg/m²*	24.5 (3.6)	25.2 (4.6)	0.34	25.3 (5.6)	25.4 (5.2)	0.96	24.6 (3.8)	25.3 (4.9)	0.29
Symptom duration, years*	2.5 (2.2)	2.7 (1.4)	0.47	2.6 (1.5)	1.9 (1.4)	0.22	2.5 (2.2)	2.4 (1.4)	0.64
HLA-B27 positive, n (%)^‡	60 (87.0)	37 (62.7)	0.002	6 (85.7)	29 (60.4)	0.40	66 (86.8)	66 (61.7)	<0.001
Anterior uveitis, n (%)^‡	7 (10.1)	6 (10.2)	1.0	0	1 (2.1)	1.0	7 (9.2)	7 (6.5)	0.58
IBD, n (%)^‡	0	0	1.0	0	1 (2.1)	1.0	0	1 (0.9)	1.0
PsO, n (%)^‡	8 (11.6)	10 (17.0)	0.45	0	5 (10.4)	1.0	8 (10.5)	15 (14.0)	0.51
PsO family history, n (%)^‡	4 (5.8)	1 (1.7)	0.38	0	3 (6.3)	1.0	4 (5.3)	4 (3.7)	0.72
ASDAS-CRP	3.1 (1.1)	3.1 (0.9)	0.98	2.3 (1.2)	2.8 (0.8)	0.11	3.0 (1.1)	3.0 (0.9)	0.85
CRP, mg/l	7.7 (9.6)	7.6 (14.7)	0.96	5.3 (9.3)	5.0 (7.0)	0.93	7.5 (9.6)	6.4 (11.9)	0.53
BASDAI, 0–10	5.7 (2.0)	6.4 (1.6)	0.03	4.5 (2.3)	6.0 (1.6)	0.03	5.6 (2.0)	6.2 (1.6)	0.02
BASFI, 0–10 cm VAS	3.7 (2.5)	4.6 (2.6)	0.04	3.0 (1.4)	3.9 (2.2)	0.30	3.6 (2.5)	4.3 (2.4)	0.07
BASMI, 0–10	1.0 (1.2)	1.4 (1.5)	0.14	1.2 (0.9)	1.4 (1.4)	0.72	1.1 (1.2)	1.4 (1.4)	0.10
SPARCC spine score, 23-DVU, 0–414	6.9 (11.9)	4.0 (5.8)	0.10	2.5 (3.9)	2.5 (3.9)	0.99	6.5 (11.5)	3.3 (5.1)	0.01
SPARCC spine score, 23-DVU 0–414, median^§	2.0	1.5	0.39	1.0	0.8	0.85	2.0	1.5	0.12

Values are mean (standard deviation) unless stated otherwise. P values are from one-way analysis of variance (ANOVA) with treatment as factor, unless stated otherwise. ASDAS-CRP Ankylosing Spondylitis Disease Activity Score based on C-reactive protein, BASDAI Bath Ankylosing Spondylitis Disease Activity Index, BASFI Bath Ankylosing Spondylitis Functional Index, BASMI Bath Ankylosing Spondylitis Metrology Index, BME bone marrow edema, BMI body mass index, CRP C-reactive protein, DVU discovertebral units, HLA human leukocyte antigen, IBD inflammatory bowel disease, PsO psoriasis, SIJ sacroiliac joint, SSS SIJ structural score, VAS visual analog scale
*P values calculated using one-way ANOVA comparing means between groups
^† P values from the chi-square test
^‡ P values from Fisher’s exact test (two-tailed)
^§ P value from the Wilcoxon-Mann-Whitney test

ISSN: 1478-6362