Table 4.

Impact of male sex on spinal radiographic progression in axSpA

Definition of progression	Variable	Cervical spine			Lumbar spine
		OR	95% CI	P value	OR	95% CI	P value
≥2 mSASSS units	Male sex (total effect)	2.57	1.23 to 5.38	0.01	2.23	1.14 to 4.40	0.02
	TNFi use prior to X-ray interval	0.65	0.39 to 1.08	0.10	0.66	0.40 to 1.11	0.12
	Length of the X-ray interval (+ 1 year)	1.04	0.52 to 2.07	0.91	1.16	0.58 to 2.32	0.67
≥1 new syndesmophyte	Male sex (total effect)	6.51	2.71 to 15.6	<0.001	5.12	2.26 to 11.6	<0.001
	TNFi use prior to X-ray interval	0.98	0.59 to 1.62	0.93	0.54	0.32 to 0.91	0.02
	Length of the X-ray interval (+ 1 year)	1.99	0.96 to 4.10	0.06	0.66	0.77 to 3.59	0.20

Results from different multivariable models with spinal radiographic progression defined as an increase of ≥2 mSASSS units in 2 years or as the formation of ≥1 new syndesmophyte in 2 years. Analyses performed in 724 radiographic intervals from 505 patients (59 events in the cervical spine and 64 events in the lumbar spine with progression defined as ≥2 mSASSS units and 62 events in the cervical spine and 69 events in the lumbar spine with progression defined as formation of ≥1 new syndesmophyte). The total effect of sex on radiographic progression includes a direct effect as well as in indirect effect via an impact of baseline spinal radiographic damage.

axSpA, axial spondyloarthritis; mSASSS, Modified Stoke Ankylosing Spondylitis Spinal Score; TNFi, tumour necrosis factor inhibitor.