Table 2

Effect of bDMARDs on the likelihood of progression: comparative studies with continuous exposure to treatment

StudyStudy designFollow-up (years)TreatmentNHandling of pretreatment confoundersDefinition of progressionOR (95% CI)
Baraliakos et al, 200534OLE versus cohort (GESPIC)2INF41Adjust. (not clear which variables)≥1 mSASSS1.5 (0.4 to 6.5)*
No TNFi41
van der Heijde et al, 200831OLE versus cohort (OASIS)2INF165Match. (inclusion criteria), adjust. (mSASSS) and strat. (gender, age, CRP, BASDAI, BASFI, BASMI, PGA and HLA-B27)≥1 mSASSS0.9 (0.6 to 1.5)†
No TNFi61
Haroon et al, 201339Cohort1.5–9TNFi201PS matching‡≥1 mSASSS/year0.3 (0.1 to 0.8)‡
No TNFi133
Kim et al, 201640Cohort2–5TNFi269PS matching§≥2 mSASSS0.7 (0.3 to 1.6)§
No TNFi341
  • *Calculated from observed data (p value of adjusted analysis not significant and no adjusted effect size reported).

  • †Calculated from observed data in the matched cohorts (adjusted and stratified analyses also not significant).

  • ‡Adjusted OR after PS matching (n=142); baseline variables used to estimate the PS: gender, HLA-B27, BASDAI, ESR, mSASSS, NSAID index, disease duration, smoking pack-years and age of onset of symptoms.

  • §adjusted OR after PS matching (n=166 in each group); baseline variables used to estimate the PS: age, gender and CRP.

  • adjust, adjustment; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; bDMARDs, biological disease-modifying antirheumatic drugs; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; GESPIC, German Spondyloarthritis Inception Cohort; HLA, human leukocyte antigen; INF, infliximab; Match, matching; mSASSS, modified Stoke Ankylosing Spondylitis Spinal Score; NSAIDs, non-steroidal anti-inflammatory drugs; OASIS, Outcome in AS International Study; OLE, open-label extension; PGA, patient global assessment; PS, propensity score; strat, stratification; TNFi, tumour necrosis factor alpha inhibitor.