Table 3

Baseline observed patient and disease characteristics per latent class in SPACE and DESIR

	SPACE				DESIR
	‘Axial’ (n=64)	‘IBP+peripheral’ (n=92)	‘At risk’ (n=99)	‘No SpA’ (n=210)	‘Axial’ (n=110)	‘IBP+peripheral’ (n=137)	‘At risk’ (n=329)
Clinical and demographic
Age at baseline (years)	30	32	30	31	31	33	34
Male gender	66	38	32	25	73	43	40
Symptom duration (years)	1	2	2	2	2	1	2
Imaging
Inflammation on MRI-SIJ (ASAS)	86	3	0	2	88	22	8
BME on MRI-Spine (≥5 lesions)	28	2	0	1	20	0	1
Radiographic sacroiliitis (mNY)	34	11	1	2	59	5	2
≥1 syndesmophyte on X-Spine	3	7	0	3	11	6	6
SpA features
Elevated CRP (≥6 mg/dL)	50	22	24	20	56	39	16
Good response to NSAIDs (ever)	59	89	32	18	97	84	82
Peripheral arthritis (ever)	17	47	3	9	7	83	0
Dactylitis (ever)	2	19	0	2	3	55	0
Heel enthesitis (ever)	9	72	12	3	24	59	47
Current arthritis/enthesitis/dactylitis	48	87	64	68	56	88	65
HLA-B27	86	36	85	0	93	52	52
Family history of SpA	38	52	72	24	47	43	42
Psoriasis (ever)	9	35	1	7	7	29	16
Uveitis (ever)	13	7	15	2	8	12	8
IBD (ever)	3	15	0	9	1	5	5
Inflammatory back pain	67	100	69	50	100*	100*	100*
Number of SpA features (0–9)†	3	5	2	1	3	4	2
ASAS classification criteria
ASAS axSpA criteria	98	45	60	4	93	58	54
ASAS pSpA criteria	48	70	56	15	56	82	44
ASAS SpA criteria‡	98	78	79	17	99	89	64

Values are means for continuous variables or percentages for binary variables.
*By study design all patients in DESIR have IBP.
†Peripheral arthritis, heel enthesitis, dactylitis, psoriasis, uveitis, inflammatory bowel disease, good response to NSAIDs, elevated CRP and family history of SpA.
‡Fulfilment of either ASAS axSpA or ASAS pSpA classification criteria. Values in bold highlight discriminant features across latent classes. Values in italic highlight dominant features (probability >50%) within each class. SpA features are positive if ‘ever present’ (any time in the past and/or baseline).
ASAS, Assessment of SpondyloArthritis international Society; axSpA, axial spondyloarthritis; BME, bone marrow oedema; CRP, C reactive protein; DESIR, DEvenir des Spondylarthopathies Indifférenciées Récentes; IBD, inflammatory bowel disease; mNY, modified New York criteria; NSAIDs, non-steroidal anti-inflammatory drug; pSpA, peripheral spondyloarthritis; SIJ, sacroiliac joints; SPACE, SPondyloArthritis Caught Early; X-Spine, radiograph of the spine.