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.