Treatment Patterns and Clinical Outcomes for Patients Living with Active Giant Cell Arteritis in Canada

Giant cell arteritis (GCA) is a chronic inflammatory vasculitis in large and medium-sized arteries. Glucocorticoids (GCs) remain the cornerstone of treatment but carry significant long-term adverse effects. Tocilizumab (TCZ), an interleukin (IL)-6 receptor inhibitor, has become a GC-sparing agent, yet optimal treatment duration remains uncertain.

This retrospective cohort study evaluated treatment patterns, clinical outcomes, and GC burden in patients (N = 121) with GCA treated at a specialized clinic in Montreal, Canada, between January 2017 and February 2025. Patients were stratified by initial treatment: GC only, GC + TCZ, and GC + other immunosuppressants (OIS). The primary endpoint was sustained remission at 12 months, defined by symptom resolution and normalization of inflammatory markers maintained for ≥ 6 months.

Overall, two-thirds of patients (83, 68.6%) (95% confidence interval [CI] 60.3-76.9%) achieved sustained remission, with similar rates in GC only (35, 72.9%) and GC + TCZ (44, 69.8%) groups, but lower in the GC + OIS group (4, 40.0%). Most patients remained on GCs after 1 year, highlighting the difficulty of achieving steroid-free remission. Relapses occurred in nearly half of patients (58, 47.9%), with a median time to first relapse of 283.5 days (95% CI 206-326). Methotrexate showed limited GC-sparing efficacy, with several patients relapsing (6, 60%). TCZ-treated patients had the lowest cumulative GC exposure (mean 3431 mg (standard deviation [SD] = 1049) vs. 4690 mg (SD 969) in GC only), though a quarter of patients (16, 25.4%) relapsed after TCZ discontinuation.

The current 1-year TCZ treatment limit in Canada may be inadequate for long-term disease control. Adverse events were generally low, though hypertension, hyperglycemia, and infections were common. Two bowel perforations occurred in the TCZ group. These findings underscore the need for individualized, long-term treatment in GCA to minimize steroid exposure and maintain disease control. Future research should explore optimal therapy durations and support policy changes to expand access to steroid-sparing agents to improve long-term GCA outcomes.