Table 4

Original data and data with IPTW

CovariatesOriginal dataData with IPTW
Off the TNFisOn the TNFisSMDOff the TNFisOn the TNFisSMD
Age, mean (SD), year32.66 (8.80)32.74 (8.80)0.00933.25 (9.23)33.03 (8.97)0.024
Female (%)101 (10.6)120 (10.7)0.00488.2 (10.5)107.0 (10.8)0.011
Eye involvement (%)468 (49.0)549 (48.8)0.002447.6 (53.2)506.7 (51.3)0.038
Peripheral joint involvement (%)540 (56.5)630 (56.0)0.009511.4 (60.8)583.5 (59.1)0.035
ESR at the start of the interval, mean (SD), log2.30 (1.07)2.52 (1.17)0.1902.42 (1.14)2.51 (1.19)0.071
CRP at the start of the interval, mean (SD), log0.02 (0.47)0.17 (0.64)0.2760.14 (0.62)0.19 (0.66)0.083
BASDAI at the start of the interval, mean (SD), square root1.60 (0.57)1.84 (0.72)0.3651.72 (0.63)1.82 (0.74)0.144
mSASSS at the start of the interval, mean (SD)20.00 (20.07)19.43 (19.96)0.02820.98 (20.14)20.17 (20.32)0.040
cDMARDs* (%)27 (2.8)56 (5.0)0.11242.2 (5.0)53.6 (5.4)0.019
NSAIDs* (%)101 (10.6)307 (27.3)0.438160.4 (19.1)206.3 (20.9)0.046
*Glucocorticoids (%)16 (1.7)17 (1.5)0.01335.6 (4.2)16.3 (1.7)0.153
  • *Number of patients prescribed with drugs for >50% of the interval period.

  • BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; cDMARDs, conventional disease-modifying anti-rheumatic drugs; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; IPTW, inverse probability of treatment weighting; mSASSS, modified Stoke Ankylosing Spondylitis Spinal Score; NSAIDs, non-steroidal anti-inflammatory drugs mSASSS change per year with and without TNFi therapy; SMD, standardised mean difference; TNFis, tumour necrosis factor inhibitors.