Table 1

Baseline characteristics at first radiograph

Male sex, %43265.7
HLA-B27 positive, %39180.6
Age, years43240.3 (11.0)
Symptom duration, years42413.8 (9.7)
BASDAI3694.2 (2.3)
ASDAS3512.8 (1.1)
CRP (mg/L), median (IQR)3658.0 (3.0; 11.0)
Elevated CRP, %36440.4
BASFI3733.1 (2.6)
BASMI3752.2 (2.0)
mSASSS, median (IQR)4321.0 (0.0; 6.0)
mean (SD)6.6 (12.5)
Syndesmophytes present, %43234.3
EQ-5D37065.1 (21.6)
Current peripheral arthritis, %37828.6
Current enthesitis, %38154.3
BMI 25–30, %37329.5
BMI >30, %37315.6
On NSAID treatment, %34183.9
On TNFi treatment, %43237.7
Ever TNFi treatment, %43243.1
Years of TNFi treatment in treated patients1632.1 (1.7)
Current smokers, %36538.4
Number exercise sessions per week, median (IQR)3662.0 (0.0; 2.0)
Patients with different number of radiographic intervals*, %432100
 One interval30470.4
 Two intervals8319.2
 Three intervals358.1
 Four intervals92.1
 Five intervals10.2
  • Except where indicated otherwise, values are the mean (SD).

  • *Differences in baseline characteristics in patients with different number of radiographic intervals are provided in the online supplementary table S8.

  • ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; BMI, body mass index; CRP, C reactive protein; EQ-5D, EuroQol 5-domain; HLA-B27, human leucocyte antigen B27; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score; NSAID, non-steroidal anti-inflammatory drug; TNFi, tumour necrosis factor inhibitor.