Time-dependent increased risk for serious infection from continuous use of TNF antagonists during three years in rheumatoid arthritis patients

Arthritis Care & Research , 04/27/2012

Sakai R et al. – Continuous anti–tumor necrosis factor (TNF) therapy was significantly associated with increased risks for developing serious infections (SIs) during, but not after, the first year.

Methods

  • The authors analyzed 727 RA patients who had started either infliximab (IFX) or etanercept (ETN) [the anti–TNF group, 1480.1 patient–years (PY)] and 571 RA patients who had started conventional non–biological DMARDs (the unexposed group, 1104.1 PY) at the time of enrollment in REAL.
  • They assessed the occurrence of SIs within a three–year observation period, including the period after switching to other TNF antagonists and all SIs, unlimited to the first one in each patient as reported in other studies, to evaluate the real safety of TNF antagonists in daily practice.

Results

  • The incidence rate of SIs per 100 PY was 5.54 (95% confidence interval [95% CI] 4.44–6.84) in the anti–TNF group and 2.72 (95% CI, 1.87–3.83) in the unexposed group.
  • Poisson regression analysis revealed that the relative risk (RR; 95% CI) of continuous use of TNF antagonists for SIs after adjusting for baseline and time–dependent covariates was significantly elevated both for overall [1.97(1.25–3.19)] and for the first year [2.40 (1.20–5.03)], but not for the second and third years combined [1.38 (0.80–2.43)].
  • The adjusted RR for SIs of ETN compared to IFX was not significantly elevated.

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