Objective. To assess the risk of serious infections following 22 weeks of infliximab therapy, and to further characterize the safety profile of infliximab in combination with background treatments during 1 year in patients with rheumatoid arthritis (RA) with various comorbidities.Methods. Patients with active RA despite receiving methotrexate (MTX) were randomly assigned to receive infusions of placebo (group 1, n ؍ 363), 3 mg/kg infliximab (group 2, n ؍ 360), or 10 mg/kg infliximab (group 3, n ؍ 361) at weeks 0, 2, 6, and 14. At week 22, patients in placebo group 1 began receiving 3 mg/kg infliximab, and patients in group 3 continued to receive an infliximab dose of 10 mg/kg. Patients in group 2 who failed to meet predefined response criteria received increasing doses of infliximab in increments of 1.5 mg/kg.Results. At week 22, the relative risk of developing serious infections in groups 2 and 3, compared with group 1, was 1.0 (95% confidence interval [95% CI] 0.3-3.1, P ؍ 0.995) and 3.1 (95% CI 1.2-7.9, P ؍ 0.013), respectively. The incidence of serious adverse events was 7.8% in groups 2 and 3 compared with 7.5% in group 1. From week 22 to week 54, 11.8%, 9.9%, and 10.3% of patients in groups 1, 2, and 3, respectively, reported occurrences of serious adverse events. Through week 54, 1 patient in group 1, 2 patients in group 2, and 4 patients in group 3 developed active tuberculosis.Conclusion. The risk of serious infections in patients receiving the approved infliximab dose of 3 mg/kg plus MTX was similar to that in patients receiving MTX alone. Patients receiving the unapproved induction regimen of 10 mg/kg infliximab plus MTX followed by a 10 mg/kg maintenance regimen had an increased risk of serious infections through week 22.
