Table 1.

Baseline demographics, disease characteristics and activity, and reasons for treatment discontinuation overall and according to clinical subdiagnosis. Values are n (%) or median (IQR) unless otherwise specified.

Variables	Valid, n	Diagnosis					p^‡
Variables	Valid, n	All, n = 1077	AS, n = 561	PsA, n = 375	uSpA, n = 108	IBD-SpA, n = 33	p^‡
Male	1077	711 (66)	446 (80)^{^c,^d,^f}	203 (54)^{^c}	51 (47)^{^d}	15 (46)^{^f}	< 0.001
Age, yrs	1077	44 (35–54)	41 (33–50)^{^c}	49 (39–59)^{^c,^e,^g}	41 (33–52)^{^e}	43 (33–54)^{^g}	< 0.001
Symptom duration, yrs	1077	9 (3–17)	13 (6–20)^{^c,^d,^f}	6 (2–12)^{^c}	4 (1–11)^{^d}	6 (2–11)^{^f}	< 0.001
Symptom duration < 5 yrs	1077	352 (33)	115 (21)^{^c,^d,^f}	166 (44)^{^c}	56 (52)^{^d}	15 (46)^{^f}	< 0.001
TNFi
IFX	1077	655 (61)	382 (68)^{^c,^d}	203 (54)^{^c}	49 (45)^{^d}	21 (64)	< 0.001
ETN	1077	200 (19)	81 (14)^{^c,^d}	89 (24)^{^c,^g}	27 (25)^{^d,^h}	3 (9)^{^g,^h}	< 0.001
ADA	1077	184 (17)	87 (16)	64 (17)	24 (22)	9 (27)	0.144
GOL	1077	38 (3.5)	11 (2)^{^c,^d}	19 (5)^{^c}	8 (7)^{^d}	0 (0)	0.005
Followup, yrs	1077	2.8 (1.0–5.9)	2.9 (1.0–7.3)^{^d}	2.8 (1.0–5.4)	2.1 (0.7–4.5)^{^d}	2.3 (0.9–3.9)	0.024
Axial inflammatory arthritis	913	770 (84)	561 (100)^{^c,^d,^f}	121 (53)^{^c,^e,^g}	70 (73)^{^d,^e}	22 (76)^{^f,^g}	< 0.001
Peripheral arthritis	944	652 (69)	209 (46)^{^c,^d,^f}	336 (94)^{^c,^e,^g}	88 (87)^{^d,^e}	22 (76)^{^f,^g}	< 0.001
No. previous csDMARD	1059	1 (0–2)	0 (0–1)^{^c, ^d}	1 (1–2)^{^c,^e}	1 (1–2)^{^d,^e}	1 (1–2)	< 0.001
No. co-administered csDMARD	1070	0 (0–1)	0 (0–1)^{^c,^d,^f}	1 (1–1)^{^c}	1 (0–1)^{^d}	1 (0–1)^{^f}	< 0.001
Co-administered csDMARD
MTX	1020	405 (40)	100 (18)^{^c,^d,^f}	232 (66)^{^c,^g}	62 (58)^{^d,^h}	11 (36)^{^f,^g,^h}	< 0.001
Other	1020	124 (12)	29 (5)^{^c,^d,^f}	62 (18)^{^c,^g}	18 (17)^{^d,^h}	13 (42)^{^f,^g,^h}	< 0.001
Monotherapy	1070	544 (51)	417 (74)^{^c,^d,^f}	86 (23)^{^c}	32 (30)^{^d}	12 (36)^{^f}	< 0.001
Ongoing corticosteroids	1010	115 (11)	24 (5)^{^c,^d,^f}	61 (17)^{^c}	25 (24)^{^d}	5 (16)^{^f}	< 0.001
BASDAI, 0–10 ^{^a}	507	5.1 (4.0–6.4)	5.1 (3.8–6.4)	5.2 (4.2–6.2)	5.6 (4.3–7.2)	5.2 (4.1–6.9)	0.303
BASFI, 0–10 ^{^a}	453	5.1 (3.3–6.9)	5.1 (3.2–7.0)	5.1 (3.4–6.9)	5.0 (3.4–6.6)	3.7 (2.6–6.8)	0.891
ASDAS-CRP ^{^a}	440	3.4 (2.8–4.1)	3.5 (2.8–4.1)	3.5 (2.5–4.1)	3.4 (2.4–4.2)	3.4 (3.0–3.8)	0.743
CRP, mg/dl	712	1.2 (0.4–2.7)	1.5 (0.6–3.0)^{^c,^d,^f}	1.1 (0.3–2.3)^{^c}	0.9 (0.3–2.6)^{^d}	0.6 (0.3–1.1)^{^f}	0.001
ESR, mm/h	785	30 (16–48)	29 (16–49)	30 (18–48)	25 (13–48)	24 (18–45)	0.545
VAS global, 0–100	796	60 (50–80)	60 (50–80)	65 (50–80)	70 (45–80)	70 (60–80)	0.213
VAS pain, 0–100	760	65 (50–80)	60 (50–80)	70 (50–80)	70 (50–80)	70 (58–80)	0.709
PGA, 0–4	692	3 (2–3)	3 (2–3)^{^d}	3 (2–3)^{^e}	3 (3–3)^{^d,^e}	3 (2.8–3)	0.001
Tender joint count^{^b}	519	3 (1–8)	1 (0–3)^{^c,^d}	5 (2–11)^{^c,^e}	2 (0–5)^{^d,^e}	5 (0–11)	< 0.001
Swollen joint count^{^b}	519	2 (0–6)	0 (0–1)^{^c,^d,^f}	4 (1–8)^{^c,^e}	2 (1–4)^{^d,^e}	2 (0–6)^{^f}	< 0.001
DAS28-ESR^{^b}	483	4.5 (3.6–5.4)	3.8 (3.1–4.6)^{^c,^d,^f}	5.1 (4.2–6.2)^{^c,^e}	4.4 (3.6–5.3)^{^d,^e}	4.7 (4.0–5.5)^{^f}	< 0.001
HAQ (0–3)^{^b}	305	0.8 (0.5–1.3)	0.9 (0.5–1.3)	0.9 (0.5–1.3)	0.6 (0.3–1.1)	0.8 (0.3–1.1)	0.241
Reasons for discontinuation, n (% of stops) [n/100 patients/yr]
Inefficacy	1077	175 (43) [4.1]	71 (36) [2.9]	70 (47) [5.1]	23 (55) [7.3]	11 (61) [9.8]
Primary inefficacy	1077	83 (21) [1.9]	34 (17) [1.4]	32 (22) [2.3]	15 (36) [4.7]	2 (11) [1.8]
Secondary inefficacy	1077	92 (23) [2.2]	37 (19) [1.5]	38 (26) [2.8]	8 (19) [2.5]	9 (50) [8.0]
Adverse events	1077	159 (39) [3.7]	90 (46) [3.6]	53 (36) [3.9]	11 (26) [3.5]	5 (28) [4.5]
Other	1077	70 (17) [1.6]	34 (17) [1.4]	26 (18) [1.9]	8 (19) [2.5]	2 (11) [1.8]
Total	1077	404 [9.4]	195 [7.8]	149 [10.9]	42 [13.3]	18 [16.1]

↵‡ p values are determined by chi-square test or Kruskal-Wallis test as appropriate.
↵a In patients with axial involvement.
↵b In patients with peripheral involvement. P values are for the comparison between the following patients:
↵c p < 0.05 for AS and PsA;
↵d p < 0.05 for AS and uSpA;
↵e p < 0.05 for PsA and uSpA;
↵f p < 0.05 for AS and IBD-related SpA.
↵g p < 0.05 for PsA and IBD-related SpA;
↵h p < 0.05 for uSpA and IBD-related SpA. Several patients in subgroups had missing baseline data for some variables. TNFi: tumor necrosis factor inhibitor; IFX: infliximab; ETN: etanercept; ADA: adalimumab; GOL: golimumab; csDMARD: conventional synthetic disease-modifying antirheumatic drugs; MTX: methotrexate; BASDAI: Bath Ankylosing Spondylitis Disease Activity Score; BASFI: Bath Ankylosing Spondylitis Functional Index; ASDAS-CRP: Ankylosing Spondylitis Disease Activity Score using C-reactive protein; ESR: erythrocyte sedimentation rate; VAS: visual analog scale; PGA: physician’s global assessment; DAS28-ESR: 28-joint Disease Activity Score using ESR; HAQ: Health Assessment Questionnaire; AS: ankylosing spondylitis; PsA: psoriatic arthritis; uSpA: undifferentiated spondyloarthritis; IBD: inflammatory bowel disease; IQR: interquartile range.