Table 3

Estimated difference in BASDAI or ASDAS-CRP drop following start of a first TNFi induced by different covariates after stratification for baseline CRP levels

 Difference in ΔBASDAIDifference in ΔASDAS-CRP
BASDAI units95% CIp ValueASDAS units95% CIp Value
Patients with elevated baseline CRP
 Smoking current vs never0.750.22 to 1.280.0050.690.30 to 1.080.001
 Smoking former vs never0.36−0.28 to−0.18 to 0.780.22
 Female vs male0.35−0.17 to 0.870.190.16−0.22 to 0.540.41
 HLA-B27 negative vs positive0.48−0.19 to−0.33 to 0.680.49
 nr-axSpA vs AS0.820.13 to 1.500.020.530.02 to 1.040.04
 Education (+5 years)−0.19−0.57 to 0.190.32−0.11−0.39 to 0.170.43
 Symptom duration (+10 years)0.10−0.19 to 0.390.510.10−0.12 to 0.320.36
 Age (+10 years)−0.02−0.30 to 0.250.87−0.08−0.29 to 0.130.44
 BMI (+5 units)0.24−0.03 to 0.500.080.13−0.07 to 0.330.20
 Exercise yes vs no−0.43−0.92 to 0.060.09−0.24−0.61 to 0.120.19
Patients with normal baseline CRP
 Smoking current vs never0.30−0.24 to 0.830.280.17−0.21 to 0.560.38
 Smoking former vs never0.590.002 to−0.31 to 0.540.59
 Female vs male0.37−0.12 to 0.860.140.11−0.25 to 0.460.55
 HLA-B27 negative vs positive0.20−0.35 to 0.760.47−0.16−0.57 to 0.260.44
 nr-axSpA vs AS1.080.55 to 1.60<0.0010.39−0.003 to 0.770.05
 Education (+5 years)−0.55−0.96 to −0.190.006−0.15−0.45 to 0.150.35
 Symptom duration (+10 years)0.01−0.28 to 0.300.94−0.03−0.25 to 0.180.77
 Age (+10 years)0.12−0.15 to 0.380.380.16−0.03 to 0.350.10
 BMI (+5 units)0.10−0.17 to 0.370.46−0.01−0.20 to 0.180.94
 Exercise yes vs no0.18−0.34 to 0.700.51−0.001−0.38 to 0.370.99
  • Effect size estimates of differences in ΔBASDAI and ΔASDAS-CRP (as demonstrated in figure 1C,D) are displayed for each indicated covariate. Models are adjusted for all covariates and for differences in baseline BASDAI and BASFI associate with each covariate. Positive coefficients signify a reduced anti-TNF response in terms of BASDAI and ASDAS-CRP drop.

  • AS, ankylosing spondylitis; ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score using the C-reactive protein (CRP); BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BMI, body mass index; HLA, human leucocyte antigen; Nr-axSpA, non-radiographic axial spondyloarthritis; p, Wald-type p value; TNFi, tumour necrosis factor inhibitor.