Table 1

Baseline demographic and clinical characteristics of patients with axial spondyloarthritis

ParameterAll patients (n=210)Non-smokers (n=139)Smokers, ≤10 cigarettes a day (n=43)Smokers, >10 cigarettes a day* (n=28)p Value†
Age, years37.1±10.638.9±10.935.2±9.632.3±8.4 0.004
Duration of symptoms, years4.2±2.74.1±2.64.4±2.94.4±2.80.658
Age of symptoms onset, years33.1±10.934.9±11.230.9±9.727.9±8.8 0.002
Fulfilment of the modified New York criteria, n (%)115 (54.8)71 (51.1)27 (62.3)17 (60.7)0.320
Male gender, n (%)107 (51.0)66 (47.5)20 (46.5)21 (75.0) 0.024
HLA-B27 (+), n (%)166 (79.0)108 (78.3)37 (86.0)21 (75.0)0.449
Peripheral arthritis, n (%)31 (14.8)23 (16.5)4 (9.3)4 (14.3)0.503
Enthesitis, n (%)46 (21.9)33 (23.7)9 (20.9)4 (14.3)0.536
Uveitis ever, n (%)42 (20.0)29 (20.9)9 (20.9)4 (14.3)0.719
Psoriasis ever, n (%)28 (13.3)22 (15.8)2 (4.7)4 (14.3)0.167
IBD ever, n (%)4 (1.9)2 (1.4)0 (0)2 (7.1)0.078
BASDAI, units NRS3.9±2.24.1±2.23.6±2.13.9±2.10.456
BASFI, units NRS2.9±2.33.0±2.32.7±2.13.1±2.60.741
BASMI (0–3)1.8±1.61.8±1.61.5±1.62.3±1.90.192
C-reactive protein, mg/l9.7±15.28.3±11.99.7±12.517.1±27.7 0.020
Treatment with NSAIDs, n (%)140 (66.7)88 (64.7)32 (74.4)20 (71.4)0.445
Treatment with DMARDs, n (%)61 (29.0)40 (30.8)13 (31.0)8 (29.6)0.992
Treatment with systemic steroids, n (%)12 (5.7)7 (5.5)3 (7.1)2 (7.4)0.883
Treatment with a TNF α blocker, n (%)5 (2.4)3 (2.3)1 (2.4)1 (3.7)0.918
mSASSS4.3±8.34.2±8.83.7±5.45.4±9.40.708
Syndesmophytes, n (%)64 (30.5)38 (27.3)15 (34.9)11 (39.3)0.356
  • Statistically significant values are in bold.

  • *This group consists of 22 patients who smoked 11–20 cigarettes a day and 6 patients who smoked >20 cigarettes a day.

  • †One-way analysis of variance or Pearson's χ2 test for intergroup differences (non-smokers—moderate smokers—heavy smokers), whatever appropriate.

  • BASDAI, the Bath Ankylosing Spondylitis Disease Activity Index; BASFI, the Bath Ankylosing Spondylitis Functional Index; BASMI, the Bath Ankylosing Spondylitis Metrology Index; DMARDs, disease-modifying antirheumatic drugs; IBD, inflammatory bowel disease; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score; NSAIDs, non-steroidal anti-inflammatory drugs; TNF α, tumour necrosis factor α.