Table 4.

BASDAI50 response in HLA-B27 negative versus HLA-B27 positive axSpA patients upon 1 year of treatment with a first TNF inhibitor after multiple imputation of missing covariate data

Analysis based on multiple imputation of missing covariate data	Unadjusted analysis					Adjusted model 1			Adjusted model 2
Variables	B27−	B27+	OR	95% CI	P	OR	95% CI	P	OR	95% CI	P
HLA-B27 negative (Ref: HLA-B27 positive)	32%	50%	0.48	0.30; 0.74	<0.001	0.57	0.37; 0.89	0.01	0.79	0.49; 1.28	0.34
Female sex (Ref: male sex)						0.56	0.39; 0.79	0.001	0.51	0.34; 0.76	0.001
Family history SpA positive						1.58	1.10; 2.27	0.01	1.59	1.07; 2.35	0.02
Elevated CRP									2.34	1.60; 3.42	<0.001
BASDAI									1.09	0.99; 1.20	0.09
Enthesitis									1.35	0.88; 2.05	0.16
Education vocational (Ref: compulsory)									2.49	1.38; 4.47	0.002
Education academic (Ref: compulsory)									2.03	1.07; 3.82	0.03
BMI 25-30 (Ref: BMI <25)									0.76	0.50; 1.17	0.21
BMI >30 (Ref: BMI ≤25)									0.41	0.23; 0.74	0.003
Age									0.97	0.95; 0.98	<0.001
Uveitis ever									1.03	0.65; 1.64	0.89
Good response to NSAIDs									1.15	0.66; 1.99	0.62
nr-axSpA (Ref: r-axSpA)									0.64	0.40; 1.03	0.07
Current smoking									0.69	0.46; 1.02	0.06

Statistically significant results are shown in bold. BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASMI, Bath Ankylosing Spondylitis Mobility Index; BMI, body mass index; CRP, C-reactive protein; HLA-B27, human leucocyte antigen-B27; nr-axSpA, nonradiographic axial spondyloarthritis; NSAIDs, non-steroidal anti-rheumatic drugs; r-axSpA, radiographic axial spondyloarthritis; Ref, reference; TNFi, tumor necrosis factor inhibitor