Is Etanercept 25 mg Once Weekly as Effective as 50 mg at Maintaining Response in Patients with Ankylosing Spondylitis? A Randomized Control Trial

Objective. To investigate, in a pilot randomized controlled trial, whether etanercept (ETN) 25 mg once weekly is effective at maintaining a clinical response in patients with ankylosing spondylitis (AS) who have responded to the standard 50 mg dose. Methods. Adults with AS not responding to conventional therapies were prescribed ETN 50 mg once weekly for 6 months. Responders as defined by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were randomly assigned to taper to 25 mg once weekly or continue on 50 mg and followed for a further 6 months. The primary outcome measure was maintenance of a 50% reduction in the BASDAI or fall in BASDAI by >= 2 units and a >= 2-unit reduction in BASDAI spinal pain as measured on a 10-point visual analog scale at 6 months postrandomization. Results. Of 89 patients assessed for eligibility, 59 were enrolled; 47 (80%) had sufficient clinical response and were eligible for randomization, 24 were assigned to continue receiving ETN 50 mg, and 23 to taper to 25 mg. After 6 months, 20 (83%) of the 50 mg arm maintained clinical response compared with 12 (52%) of the 25 mg arm (a difference of -31%, 95% CI -58% - -5%). Conclusion. Although this pilot study demonstrates that treatment with ETN 25 mg was less effective at maintaining treatment response in the stepdown phase, 52% of participants maintained treatment response. Future research should address which patients are suitable for tapering.