Table 2

Clinical characteristics, disease activity and treatment of patients with purely axial SpA and combined axial and peripheral SpA

Purely axial SpA
(n=112)
Axial SpA with peripheral symptoms
(n=118)
P value
Age, median (IQR) years39 (32–48)44 (34–54)0.064
Disease duration, median (IQR) years3.1 (0.4–11.1)4.6 (1.2–12.6)0.080
Age at disease onset, median (IQR) years32 (23–38)34 (24–44)0.214
Time to diagnosis, median (IQR) years1.0 (0.3–4.0)0.8 (0.1–4.7)0.257
Male gender, %70 (63)75 (64)0.868
HLA-B27 positive, %86 (80)84 (72)0.163
Back pain (history/presence), %112 (100)118 (100)NA
Sacroiliitis mNY, %82 (73)79 (68)0.346
Peripheral arthritis (history/presence), %0 (0)75 (64)<0.001
Enthesitis (history/presence), %0 (0)73 (62)<0.001
Dactylitis (history/presence), %0 (0)9 (8)0.003
Uveitis (history/presence), %28 (25)31 (26)0.825
Psoriasis (history/presence), %7 (6)16 (14)0.065
IBD (history/presence), %7 (6)7 (6)0.920
Positive SpA family history, %41 (37)45 (38)0.811
Patient's global assessment, median (IQR) 0–100 mm52 (23–68)61 (45–75)0.001
Physician's global assessment, median (IQR) 0–100 mm44 (16–60)53 (33–62)0.009
BASDAI, median (IQR)4.4 (2.9–6.0)5.4 (4.0–6.6)0.001
 BASDAI ≥4, %64 (58)85 (75)0.007
 BASDAI #2 back pain, median (IQR)6 (3–8)7 (4–8)0.272
ASDAS-CRP, median (IQR)2.6 (1.8–3.5)3.0 (2.2–3.7)0.014
 ASDAS-CRP ≥2.1, %59 (67)78 (82)0.019
SJC, median (IQR) 0–66 joints0.0 (0.0–0.0)0.0 (0.0–1.0)<0.001
TJC, median (IQR) 0–68 joints0.0 (0.0–0.0)1.0 (0.0–3.5)<0.001
Schober, median (IQR) cm3.0 (2.0–4.0)4.0 (3.0–5.0)0.001
Chest expansion, median (IQR) cm5.0 (4.0–6.0)4.0 (3.0–6.0)0.120
CRP, median (IQR) mg/L3.3 (1.0–8.5)4.0 (1.1–14.2)0.288
ESR, median (IQR) mm/h8.0 (5.0–15.3)12.0 (4.5–24.5)0.078
NSAIDs, %85 (76)87 (74)0.706
Corticosteroids, %1 (1)3 (3)0.339
Any csDMARD, %5 (5)27 (23)<0.001
Anti-TNF therapy, %16 (14)20 (17)0.578
  • Significance of the comparisons is determined by Mann-Whitney U tests for continuous variables or χ2 tests for categorical variables. Data were missing for diagnostic delay n=153, HLA-B27 n=25, BASDAI n=10, CRP n=57, SJC/TJC n=2, Schober n=11 and ESR n=47 individuals.

  • ASAS, Assessment of SpondyloArthritis international Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; IBD, inflammatory bowel disease; NSAID, non-steroidal anti-inflammatory drug; SJC, swollen joint count; SpA, spondyloarthritis; TJC, tender joint count; TNF, tumour necrosis factor; csDMARD, conventional synthetic disease-modifying anti-rheumatic drug.