Table 3

Association between mSASSS change rate and covariates

Independent variable	Univariate model				Multivariable model
	Beta estimate*	95% CI		P value	Beta estimate*	95% CI		P value
	Beta estimate*	Lower bound	Upper bound	P value	Beta estimate*	Lower bound	Upper bound	P value
Age at diagnosis	0.017	0.005	0.028	0.004	0.012	−0.002	0.025	0.085
Sex (female)	−0.415	−0.714	−0.117	0.006	−0.561	−0.883	−0.239	0.001
HLA-B27 positivity	0.587	0.050	1.123	0.032	–	–	–	–
Eye involvement	0.432	0.142	0.721	0.003	0.420	0.124	0.717	0.005
Peripheral joint involvement	−0.215	−0.511	0.081	0.155	−0.181	−0.481	0.119	0.237
ESR at the start of the interval (log)	0.128	0.050	0.206	0.001	0.199	0.093	0.305	<0.001
CRP at the start of the interval (log)	0.006	−0.045	0.058	0.811	–	–	–	–
BASDAI at the start of the interval (square root)	−0.100	−0.245	0.044	0.173	−0.225	−0.406	−0.043	0.015
mSASSS at the start of the interval	−0.001	−0.014	0.012	0.920	–	–	–	–
cDMARDs†	−0.335	−0.538	−0.133	0.001	−0.241	−0.494	0.013	0.063
NSAIDs†	−0.079	−0.209	0.051	0.235	–	–	–	–
Glucocorticoids†	0.134	−0.283	0.552	0.529	–	–	–	–
TNFis	−0.054	−0.099	−0.009	0.017	−0.054	−0.101	−0.008	0.022

*Unstandardised regression coefficient.
†Number of intervals prescribed with drugs for >50% of the interval period.
BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; cDMARDs, conventional disease-modifying anti-rheumatic drugs; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; HLA, human leucocyte antigen; mSASSS, modified Stoke Ankylosing Spondylitis Spinal Score; NSAIDs, non-steroidal anti-inflammatory drugs; TNFis, tumour necrosis factor inhibitors.