Table 3.

Characteristics of the patients with axial spondyloarthritis stratified by calprotectin percentiles. All results are mean (with standard deviation), except those with an asterisk* which are median [with interquartile range], and those marked with a “^§” which are number of patients (%). Abbreviations: BMI body mass index, CRP C-reactive protein, ESR erythrocyte sedimentation rate, BASDAI Bath Ankylosing Spondylitis Disease Activity Index, BASFI Bath Ankylosing Spondylitis Functional Index, ASDAS Ankylosing Spondylitis Disease Activity Score

Serum calprotectin quartile [μg/ml]	0–1.6	1.6–2.4	2.4–3.9	3.9–13	p value
n	113	113	112	113
Disease duration, years	10.4 (10.2)	8.5 (9.8)	9.9 (9.8)	10.6 (9.4)	0.37
Age years	45.9 (11.4)	44.4 (12.7)	43.0 (11.3)	42.7 (13.7)	0.20
Gender = male§	62 (54.9)	62 (54.9)	67 (59.8)	77 (68.1)	0.03
BMI kg/m2	25.3 (4.7)	26.3 (4.8)	26.3 (5.4)	26.3 (4.7)	0.44
ESR mm/h*	6.0 [4.0, 11.5]	8.0 [4.0, 17.5]	8.0 [4.0, 16.0]	10.0 [4.0, 25.0]	0.01
CRP mg/l*	3.0 [1.0, 8.0]	2.0 [1.0, 8.0]	3.0 [1.0, 8.0]	4.0 [2.0, 13.0]	< 0.01
BASDAI score	3.6 (2.3)	4.0 (2.4)	3.5 (2.4)	4.1 (2.3)	0.19
BASFI score	2.1 (2.3)	2.7 (2.6)	2.3 (2.3)	2.8 (2.5)	0.22
ASDAS score	2.1 (0.9)	2.4 (1.0)	2.2 (1.1)	2.7 (1.0)	0.01
ASDAS moderate/high§1	40/79 (50.6)	47/81 (58.0)	37/65 (56.9)	49/72 (68.1)	0.04
ASDAS remission§2	14/79 (17.7)	16/81 (19.8)	20/65 (30.8)	4/72 (5.56)	0.20
Physician global disease activity	1.9 (1.6)	2.4 (2.0)	2.2 (2.0)	2.6 (1.8)	0.02
Swollen joint count	0.4 (0.9)	0.6 (1.8)	0.4 (0.9)	0.3 (1.2)	0.46
Hip involvement§	3 (2.7)	3 (2.7)	5 (4.5)	10 (8.8)	0.02
Enthesitis§	32 (28.3)	38 (33.6)	40 (35.7)	36 (31.9)	0.68
Dactylitis§	2 (1.8)	0 (0.0)	5 (4.5)	3 (2.7)	0.51

¹Proportion of patients with an ASDAS score ≥ 2.1

²Proportion of patients with an ASDAS score < 1.3