Table 4

Radiographic progression in the spine in the FORCAST study population according to the presence/absence of definite MRI lesions in the sacroiliac joints at baseline

	SPARCC SIJ≥2*			SSS fat metaplasia ≥2			SSS erosion ≥2			SSS backfill ≥2			SSS ankylosis ≥2
	Yes N=103	No N=126	p Value	Yes N=78	No N=154	p Value	Yes N=73	No N=159	p Value	Yes N=58	No N=174	p Value	Yes N=82	No N=150	p Value
All patients
ΔmSASSS units/year (mean (SD))	0.74 (1.11)	0.94 (1.50)	0.43	1.09 (1.51)	0.73 (1.23)	0.06	0.56 (1.01)	0.98 (1.44)	0.01	0.89 (1.19)	0.84 (1.38)	0.33	1.12 (1.63)	0.70 (1.12)	0.01
Patients on standard therapy (N=98)
	Yes N=45	No N=51	p Value	Yes N=30	No N=68	p Value	Yes N=31	No N=67	p Value	Yes N=21	No N=77	p Value	Yes N=27	No N=71	p Value
ΔmSASSS units/year (mean (SD))	0.76 (1.26)	0.77 (1.08)	0.63	1.24 (1.56)	0.57 (0.86)	0.03	0.53 (0.82)	0.89 (1.27)	0.19	1.15 (1.47)	0.67 (1.04)	0.07	0.93 (1.18)	0.72 (1.14)	0.15
Patients on TNFi therapy (N=134)
	Yes N=58	No N=75	p Value	Yes N=48	No N=86	p Value	Yes N=42	No N=92	p Value	Yes N=37	No N=97	p Value	Yes N=55	No N=79	p Value
ΔmSASSS units/year (mean (SD))	0.73 (0.99)	1.06 (1.73)	0.53	0.99 (1.48)	0.86 (1.45)	0.51	0.59 (1.15)	1.05 (1.56)	0.04	0.75 (0.99)	0.96 (1.60)	0.88	1.22 (1.81)	0.69 (1.11)	0.03

*Available SPARCC SIJ scores n=229.
FORCAST, Follow Up Research Cohort in Ankylosing Spondylitis; SPARCC, Spondyloarthritis Research Consortium of Canada; SSS, SPARCC MRI SIJ Structural Scoring; TNFi, tumour necrosis factor inhibitor.