Flare in axial spondyloarthritis: investigation of meaningful changes in symptomatic outcome measures.

Objectives: To assess symptomatic outcomes associated with flare after discontinuation of non-steroidal anti-inflammatory drugs (NSAIDs) in axial spondyloarthritis (axSpA).

Methods: Patients with NSAID-refractory axSpA discontinued NSAIDs, restarted if symptoms recurred, and self-recorded Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). 75th percentiles were calculated for changes in BASDAI total and components from NSAID discontinuation to resumption.

Results: 75th percentiles for absolute/relative changes: BASDAI total (0-10)=1.5/28%; fatigue=2.0/25%; spinal pain=2.0/33%; joint pain/swelling=2.0/50%; enthesitis=2.0/43%; morning stiffness=1.5/27%.

Conclusions: No single score threshold applied but absolute change ≥2 or relative change ≥30% indicated symptomatic deterioration for most BASDAI components.