Anti-infliximab antibodies in patients with rheumatoid arthritis who require higher doses of infliximab to achieve or maintain a clinical response

Boulos Haraoui, Louise Cameron, Michèle Ouellet, Barbara White

Research output: Contribution to journalArticle


Objective. To determine whether the need to use doses of infliximab greater than 3 mg/kg every 8 weeks to achieve or maintain clinical response in patients with rheumatoid arthritis (RA) is associated with differences in baseline clinical characteristics or anti-infliximab antibodies. Methods. Baseline clinical characteristics and anti-infliximab levels were evaluated retrospectively in a cohort of 51 consecutive patients with RA treated with infliximab at a single center. Patients were divided into 2 groups for comparison: Group 1 patients achieved and maintained clinical responses with infliximab 3 mg/kg every 8 weeks; Group 2 patients required higher doses. Results. Thirty-two (63%) patients required infliximab dose escalation (Group 2). There were no statistically significant differences in baseline or clinical characteristics between Group 1 and Group 2 patients. Anti-infliximab antibodies occurred in 47% of Group 2 versus 27% of Group 1 patients, with higher anti-infliximab antibody concentrations in Group 2 patients (mean ± SD: 18.3 ± 8.9 g/ml vs 7.5 ± 4.8 g/ml; p = 0.02). Patients who developed anti-infliximab antibodies were younger and receiving less prednisone at the time of infliximab initiation than patients who did not. Conclusion. Finding higher anti-infliximab antibody concentrations in patients who needed dose escalation of infliximab to achieve or maintain clinical responses with lower serum trough levels of infliximab suggests that development of anti-infliximab antibodies may reduce clinical efficacy of infliximab in some patients with RA.

Original languageEnglish (US)
Pages (from-to)31-36
Number of pages6
JournalJournal of Rheumatology
Issue number1
StatePublished - Jan 2006
Externally publishedYes



  • Anti-infliximab antibodies
  • Clinical response
  • Dose escalation
  • Infliximab
  • Rheumatoid arthritis

ASJC Scopus subject areas

  • Rheumatology
  • Immunology

Cite this