Sex differences in medication discontinuation in axial spondyloarthritis.

Objective We examined sex differences in medication discontinuation among patients with axial spondyloarthritis (axSpA) initiating tumor necrosis factor inhibitors (TNFi), interleukin‐17 inhibitors (IL‐17i), or Janus kinase inhibitors (JAKi). Methods Using data from the Rheumatology Informatics System for Effectiveness (RISE) Registry (2003–2025), we assessed medication discontinuation by sex among new users of TNFi, IL‐17i, and JAKi. Cox regression models were used to evaluate associations between sex and treatment discontinuation, adjusting for sociodemographic and clinical factors. We also examined medication continuation by sex and age group (18–64 vs > 65 years) using Kaplan‐Meier curves and tested for interactions between sex and age, race, and Area Deprivation Index (ADI). Results Among 7,200 individuals, the mean (SD) age was 52.7 (14.7) years; 58.3% were female and 68.7% were non‐Hispanic White. Among TNFi users (N=6,256), females had a 24% higher risk of discontinuation compared to males (HR: 1.24; 95% CI: 1.16–1.32). Among IL‐17i users (N=693), females had a 25% higher risk of discontinuation (HR: 1.25; 95% CI 1.01‐1.54). No significant sex differences were observed among JAKi users (N=251). Among TNFi users, females under 65 had the lowest probability of treatment continuation. There was no statistically significant interaction between sex and age, race or ADI. Conclusions In a large U.S. registry, females with axSpA were more likely to discontinue TNFi and IL‐17i than men. Larger studies with longer follow‐up since treatment approval are needed to confirm the lack of sex differences in JAKi discontinuation as this group could be underpowered.