Maintenance of infliximab treatment in ankylosing spondylitis

Objective. Continuous treatment with the antitumor necrosis factor alpha (anti-TNF alpha) antibody infliximab is efficacious in ankylosing spondylitis (AS), whereas treatment discontinuation results in disease relapse, with variable delay. This study was undertaken to compare the efficacy of continuous treatment with infliximab with that of a treatment regimen adapted to symptom recurrence. Methotrexate (MTX) in combination with infliximab was also tested. Methods. Patients with active AS were randomly assigned at week 0 to receive infliximab every 6 weeks (continuous treatment) or upon symptom recurrence (on-demand treatment), following infusions at weeks 4, 6, and 10. Patients in the on-demand group were randomly assigned to receive either MTX in combination with infliximab or infliximab alone. Patients were monitored for 1 year. The primary end point was the proportion of patients who met the Assessment in AS International Working Group criteria for 20% improvement (ASAS20) at week 58. Results. Of 247 patients, 124 were assigned to receive infliximab every 6 weeks and 123 to receive on-demand treatment. Among the latter, 62 received MTX, and 61 received infliximab alone. A greater proportion of patients receiving infliximab every 6 weeks fulfilled ASAS20 response criteria at week 58 than did patients receiving on-demand treatment (75% versus 46%; P < 0.0001). Patients in the continuous treatment group received more infliximab infusions after week 10 than did those in the on-demand group (mean +/- SD 5.8 +/- 2.2 versus 3.5 +/- 2; P < 0.0001). Addition of MTX did not significantly affect the proportion of patients with an ASAS20 response at week 58, nor the number of infliximab infusions administered. Conclusion. These findings indicate that continuous treatment of AS with infliximab is more efficacious than on-demand treatment, and that the addition of MTX to infliximab provides no significant benefit.