Prospective observational analysis of the efficacy and safety of low-dose (3 mg/kg) infliximab in ankylosing spondylitis: 4-year followup.

OBJECTIVE

Although there are now compelling data that infliximab is effective for the treatment of AS, most studies have evaluated a dose of 5 mg/kg rather than the 3 mg/kg dose recommended for patients with RA. We assessed the effectiveness and safety of a 3 mg/kg dose of infliximab in normal clinical practice over several years of followup.

METHODS

All consecutive patients with AS starting infliximab therapy at 3 mg/kg IV at 0, 2, and 6 weeks and q 2 months between April 2000 and December 2004 were included. Data were systematically collected at baseline, at 14 weeks, and every 6 months thereafter to 4 years or withdrawal. Data included demographic characteristics, Bath AS indices, adverse events, and reasons for withdrawal. Survival taking low-dose infliximab was analyzed by the Kaplan-Meier method with withdrawal for lack of efficacy and/or adverse events and requirement for dose escalation constituting the endpoint.

RESULTS

Thirty-four patients (M:F = 26:8), mean age 44.9 years, mean disease duration 17.1 years, and mean BASDAI of 6.4, were studied, of whom 17 had active peripheral synovitis. Median duration of treatment with low-dose infliximab was 1507 days. Fourteen discontinued therapy after a median of 91 days, 6 for adverse events, 6 for lack of efficacy, and 2 were lost to followup. Five (14.7%) patients required dose escalation. Effectiveness demonstrable at 1 year was maintained over 4 years. We did not identify any significant baseline predictors of maintenance on low dose infliximab for > or = 2 years.

CONCLUSION

Low-dose (3 mg/kg) infliximab therapy is associated with sustained effectiveness in patients with AS in the real-world setting.