Table 1

Comparison of demographic, clinical and radiographical characteristics between axial PsA and AS with psoriasis

VariableAxial PsA
N=109
AS with psoriasis
N=127
P value
Demographic characteristics
 Age (years), mean (SD)50.1 (12.9)49.9 (12.6)0.89
 Age at diagnosis (years), mean (SD)42.2 (13.9)37.9 (12.8)0.016
 Sex (female), n (%)41 (37.6)27 (21.3)0.006
 Disease duration (years), median (IQR), mean (SD)7.0 (2.5–13.0)9.0 (5.0–18.0)0.040
 Diagnostic delay (years),* median (IQR), mean (SD)1.0 (0.0–5.0), 4.7 (8.0)3.5 (0.0–11.0), 7.2 (8.4)0.005
 BMI, mean (SD)27.8 (5.6)27.8 (5.3)0.99
 Family history of SpA, n (%)14/97 (14.4)19/113 (16.8)0.64
Clinical characteristics, n (%)
 Cervical pain12/109 (11.0)21/127 (16.5)0.22
 Inflammatory back pain92/109 (84.4)121/127 (95.3)0.005
 Alternating buttock pain41/108 (38.0)79/125 (63.2)<0.001
 Anterior uveitis3/109 (2.8)16/125 (12.8)0.005
 Inflammatory bowel disease1/108 (0.9)5/127 (3.9)0.14
 Dactylitis37/109 (33.9)31/126 (24.6)0.12
 Enthesitis38/108 (35.2)49/125 (39.2)0.53
 Peripheral arthritis85/109 (78.0)72/124 (58.1)0.001
 Nail disease47/109 (43.1)32/124 (25.8)0.005
 Psoriasis before SpA onset60/68 (88)64/83 (77)0.076
Laboratory findings
 HLA-B27, n (%)26/86 (30)62/93 (67)<0.001
 CRP (mg/L), median (IQR)9.3 (16.0)9.3 (15.9)0.99
 ESR (mm/hour), median (IQR)16.6 (17.3)19.1 (16.4)0.26
Radiographical findings
 Definite sacroiliitis (BASRI ≥2), n (%)60/109 (55.0)122/122 (100.0)<0.001
 Isolated spondylitis (no sacroiliitis), n (%)11/104 (10.6)0 (0)<0.001
 Any radiographical finding, n (%)71/104 (68.3)122/122 (100.0)<0.001
 BASRI sacroiliac joint, median (IQR)2.0 (0.0–3.0)3.0 (2.0–4.0)<0.001
 BASRI lumbar, median (IQR)0.0 (0.0–2.0)2.0 (1.0–3.0)<0.001
 BASRI cervical, median (IQR)0.0 (0.0–1.0)1.0 (0.0–3.0)<0.001
PROs
 BASDAI, median (IQR)4.2 (2.2–6.4)4.1 (2.4–6.4)0.77
 BASFI, median (IQR)3.2 (1.1–5.4)3.8 (1.7–6.6)0.12
 ASDAS-CRP, median (IQR)2.4 (1.6–3.3)2.7 (1.9–3.5)0.28
  • *Time from symptom onset to diagnosis.

  • AS, ankylosing spondylitis; ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASRI, Bath Ankylosing Spondylitis Radiology Index; BMI, body mass index; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; PRO, patient-reported outcome; PsA, psoriatic arthritis; SpA, spondyloarthritis.