Table 2

Impact of pretreatment Ankylosing Spondylitis Disease Activity Score (ASDAS) on spinal radiographic progression

VariableOR 95% CIp Value
TNFi use before radiographic interval yes/no0.520.29 to 0.920.02
ASDAS at start of TNFi and ASDAS at inclusion for non-treated patients1.331.00 to 1.780.05
mSASSS at start of each radiographic interval1.071.04 to 1.09<0.001
Male sex2.101.07 to 4.120.03
Disease duration (5 years)1.130.99 to 1.290.07
Current smoking1.040.59 to 1.860.88
HLA-B271.030.46 to 2.290.94
Number of exercise sessions per week0.950.82 to 1.100.47
Peripheral arthritis0.870.48 to 1.600.66
NSAID use at start of each radiographic interval0.830.41 to 1.680.60
BMI 25–30 (Reference: BMI <25)1.390.77 to 2.490.27
BMI >30 (Reference: BMI <25)1.660.81 to 3.390.16
Duration of radiographic interval1.660.85 to 3.230.14
  • Radiographic spinal progression defined as an increase in mSASSS ≥2 units. The model corresponds to the multivariable model used in figure 1A with the additional incorporation of pretreatment ASDAS in TNFi-treated patients as a covariate in order to account for confounding by indication. The ASDAS at inclusion was considered for non-TNFi-treated patients (616 radiographic intervals from 432 patients after multiple imputation of missing covariate data).

  • ASDAS, Ankylosing Spondylitis Disease Activity Score; BMI, body mass index; HLA-B27, human leucocyte antigen B27; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score; NSAID, non-steroidal anti-inflammatory drug; TNFi, tumour necrosis factor inhibitor.