Objective: The aim of this study was to access the maintenance of therapeutic response in patients with ankylosing spondylitis (AS) receiving infliximab, after prolongation of the interval between infusions.
Material and methods: In AS patients with sustained therapeutic response to infliximab administered every six weeks, a prolongation of the interval between infusions was proposed. The therapeutic response was evaluated using Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), pain, stiffness, patient's global evaluation and acute phase reactants (ESR and CPR).
Results: Twenty patients participated in the study. Sixteen were male, with a mean age of 40.3 +- 10.9 years and mean disease duration of 12 +- 9.4 years. The initial BASDAI was 59.5 +- 22.8 and initial BASFI 50.7 +- 27. The interval between infusions was lengthened to 8 +- 1 weeks (minimum 7; maximum 10) and this change occurred between 12 and 142 weeks (median 21) of treatment. The mean followup after changing the therapeutic regimen was 86 +- 45 weeks. Sixty-five percent (13/20) of the patients maintained an adequate response.
Conclusions: Two thirds of AS patients with sustained therapeutic response to infliximab administrated every six weeks maintained an adequate response with prolongation of interval between infusions. Therefore the increase of the interval between infusions seems to be an adequate option in selected patients.