Real‐world trends in prenatal antirheumatic drug utilization in Ontario, Canada: A cross‐sectional time‐series analysis

OBJECTIVES: This study aimed to describe real-world trends in preconception and prenatal use of antirheumatic drugs among pregnant individuals with rheumatic diseases in Ontario, Canada. METHODS: We conducted a time-series analysis using repeated cross-sectional data to examine annual patterns of disease-modifying antirheumatic drug (DMARD) use among pregnant individuals with rheumatoid arthritis, systemic lupus erythematosus, psoriatic arthritis, and/or axial spondyloarthritis. The study included those with Ontario Drug Benefit Program (ODB) coverage who delivered between April 1, 2006, and March 31, 2021. For calendar years 2007, 2011, 2015, and 2019, we described demographic, clinical, and DMARD use characteristics among ODB beneficiaries. RESULTS: The cohort included 5,256 pregnant individuals, with 576 preconception and 697 prenatal ODB beneficiaries. Preconception DMARD use remained relatively stable, but biological DMARD use increased by 293.1%, from 8.3 to 32.8 users per 100 eligible population from fiscal years 2006 to 2020 (p = .004). Prenatal DMARD use rose by 5.7% (p = .02), with biological DMARD use increasing by 775.0%, from 3.6 to 31.3 users per 100 eligible population (p < .001). Across the annual cohorts, the proportion of prenatal DMARD users nearly doubled from 26.3% to 45.2% (p = .01). Among users, the proportion receiving a single DMARD rose to 32.9% in 2019, while the proportion receiving 2 or more DMARDs also rose to 12.3% (p = .02). CONCLUSION: Prenatal antirheumatic drug use has increased, particularly for biological DMARDs. These trends reflect evolving treatment practices aimed at optimizing disease control and pregnancy outcomes for individuals with rheumatic diseases.