Objective: We evaluated sex differences in time to initiation of nonsteroidal anti-inflammatory agents (NSAIDs) or biologic disease modifying antirheumatic drugs (bDMARDs) among patients with axial spondyloarthritis (axSpA).

Methods: Using the 2013-2018 IBM® MarketScan® Database, we identified 174,632 axSpA patients aged ≥18 years. We evaluated the time between axSpA diagnosis and the first prescription NSAID dispensing (among those with no baseline NSAIDs use) or bDMARDs infusion/procedure claim (among those dispensed ≥ two different prescription NSAIDs in the baseline period). Adjusted hazard ratios (aHR) for time to initiation of NSAIDs or bDMARDs were computed using survival analyses. Cox proportional hazard models estimated associations between sex and predictors of treatment initiation.

Results: Average age at diagnosis was 48.2 years, 65.7% were females, and 37.8% had ≥ one NSAIDs dispensing before axSpA diagnosis. Of those without dispensing for ≥ two different prescription NSAIDs before diagnosis, NSAIDs were initiated earlier in females than males (NSAID initiators: Females (32.9%), Males (29.3%); aHR: 1.14, 95% CI: 1.11-1.16). Among those with ≥ two different prescription NSAIDs dispensations in the baseline period, 4.2% initiated a bDMARD while 77.9% continued NSAIDs use after diagnosis. Time to bDMARDs initiation was longer for females than males (aHR:0.61, 95% CI:0.52-0.72), but bDMARDs were initiated sooner among those with NSAIDs use in the baseline period.

Conclusion: Prescription NSAID use was more common than initiation of bDMARDs among patients newly diagnosed with axSpA. Females appeared more likely to continue NSAIDs after diagnosis, and the time to initiation of bDMARDs was longer for females than males.