Risk of septic arthritis in patients with rheumatoid arthritis and the effect of anti-TNF therapy: results from the British Society for Rheumatology Biologics Register.

ABSTRACT

OBJECTIVES: To evaluate the risk of septic arthritis (SA) in patients with rheumatoid arthritis (RA) treated with anti-tumour necrosis factor (TNF) therapy. METHODS: Using data from the British Society for Rheumatology Biologics Register, a prospective observational study, the authors compared the risk of SA between 11 881 anti-TNF-treated and 3673 non-biological disease-modifying antirheumatic drug (nbDMARD)-treated patients. RESULTS: 199 patients had at least one episode of SA (anti-TNF 179, nbDMARD 20). Incidence rates were anti-TNF 4.2/1000 patient years (pyrs) follow-up (95% CI 3.6 to 4.8), nbDMARD 1.8/1000 pyrs (95% CI 1.1 to 2.7). The adjusted HR for SA in the anti-TNF cohort was 2.3 (95% CI 1.2 to 4.4). The risk did not differ significantly between the three agents adalimumab, etanercept and infliximab. The risk was highest in the early months of therapy. The patterns of reported organisms differed in the anti-TNF cohort. Prior joint replacement surgery was a risk factor for SA in all patients. The rate of postoperative joint infection (within 90 days of surgery) was 0.7%. This risk was not significantly influenced by anti-TNF therapy. CONCLUSIONS: Anti-TNF therapy use in RA is associated with a doubling in the risk of SA. Physicians and surgeons assessing the RA patient should be aware of this potentially life-threatening complication.