The Impact of TNF-inhibitors on radiographic progression in Ankylosing Spondylitis

Arthritis & Rheumatism, 07/22/2013

The authors studied the effect of Tumor Necrosis Factor–Alpha (TNF)–inhibitors on progressive spine damage in Ankylosing Spondylitis (AS) patients. TNF–inhibitors appear to reduce radiographic progression in AS, especially with early initiation and longer duration of follow up.

Methods

  • All AS patients (satisfying the modified New York criteria) prospectively followed and with at least two sets of spinal radiographs at a minimum gap of 1.5 years were included (n=334).
  • Patients received clinical standard of care, which included non-steroidal anti-inflammatory drugs and TNF-inhibitors.
  • Radiographic severity was assessed by the modified Stokes Ankylosing Spondylitis Spine Score (mSASSS).
  • Patients with a rate of progression more than 1 mSASSS unit/year were considered progressors.
  • Univariable and multivariable regression analyses were done.
  • Propensity score matching (PSM) and sensitivity analysis were performed.
  • A zero-inflated negative binomial (ZINB) model was used to analyze the effect of TNF-inhibitor on change in mSASSS with varying follow-up periods.
  • Potential confounders like Bath AS Disease Activity Index (BASDAI), ESR, CRP, HLA-B27, gender, age of onset, smoking and baseline damage were included in the model.

Results

  • TNF-inhibitor treatment was associated with a 50% reduction in the odds of progression (OR: 0.52; CI: 0.30-0.88; p=0.02).
  • Patients with a delay in starting therapy of more than 10 years were more likely to progress compared to those who started earlier (OR=2.4; 95% CI: 1.09-5.3; p=0.03).
  • In the ZINB model TNF-inhibitor use significantly reduced progression when the gap between x-rays was more than 3.9 years.
  • The protective effect of TNF-inhibitors was stronger after propensity score matching.

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