Continuation of treatment with infliximab in ankylosing spondylitis: 2-yr open follow-up

Objective. To evaluate the continuation and safety of treatment with infliximab in ankylosing spondylitis (AS) over a 2-yr period. Methods. This study was an open, observational, 2-yr extension study of an open-label study of three induction infusions of infliximab in refractory AS. The fourth infusion was performed only in case of relapse. Thereafter, infliximab was to be administered as needed according to the rheumatologist's opinion; however, for some patients, infusions were performed systematically. Results. None of the 50 recruited patients was lost to follow-up. Thirteen patients (26%) interrupted their treatment by infliximab: four for inefficacy, seven for adverse events, of which four were for allergic reactions to the infusion, and two for other reasons. For all of the 46 patients who had had three infusions judged efficacious and well tolerated, a fourth infusion was performed because of a flare of the disease, after a mean interval of 20.3 +/- 9.9 weeks (range 7.3-57.9). Over the 24 months, the mean interval between infusions was 11.6 +/- 9.0 weeks. This interval was longer when patients were treated only as needed (mean 14.3 +/- 12.1 weeks) than systematically (mean 9.8 +/- 5.7 weeks). Side-effects were similar to those noted in shorter-term studies; seven patients suffered serious adverse events. There were no deaths, no malignancies and no tuberculosis. Conclusion. This study confirms the long-term treatment continuation of infliximab in AS, and shows an acceptable safety profile. It appears that for some patients the disease can be controlled with long intervals between infusions; these findings warrant further studies.