To identify risk factors for surgical site infection (SSI) in patients with rheumatoid arthritis (RA) with special attention for anti-tumor necrosis factor (anti-TNF) treatment.

All patients with RA who had undergone elective orthopedic surgery since introduction of anti-TNF were included in a retrospective parallel-cohort study with a one-year followup. Primary endpoint was a SSI according to the 1992 Centers for Disease Control and Prevention criteria and/or antibiotic use. Cohort 1 did not use anti-TNF, cohort 2 used anti-TNF but had either stopped (2A) or continued anti-TNF preoperatively (2B), the cutoff point being set at 4 times the half-life time of the drug. Infection rates were compared between cohorts, and logistic regression analysis was performed to examine risk factors.

In total, 1219 (768 patients) procedures were included, and crude infection risks were 4.0% (41/1023), 5.8% (6/104), and 8.7% (8/92) in cohorts 1, 2A, and 2B, respectively. Elbow surgery (OR 4.1, 95% CI 1.6-10.1), foot/ankle surgery (OR 3.2, 95% CI 1.6-6.5), and prior skin or wound infection (OR 13.8, 95% CI 5.2-36.7) were associated with increased risk of SSI, whereas duration of surgery (OR 0.42, 95% CI 0.23-0.78) and sulfasalazine use (OR 0.21, 95% CI 0.05-0.89) were associated with decreased risk. Perioperative use of anti-TNF was not significantly associated with an increase in SSI rates (OR 1.5, 95% CI 0.43-5.2).

The most important risk factor for SSI is history of SSI or skin infection. Although our study was not powered to detect small differences in infection rates, perioperative continuation of anti-TNF does not seem to be an important risk factor for SSI.