Giant cell arteritis in clinical practice: beyond GiACTA

Objectives: Giant cell arteritis (GCA) therapy relies on high-dose glucocorticoids (GCs), which are associated with a high incidence of side effects and GCA relapses, highlighting the need for steroid-sparing agents such as tocilizumab (TCZ) and methotrexate (MTX). The aims of this study were to analyse GC side effects and to assess the steroid-sparing efficacy of TCZ and MTX in a real-life cohort of patients with GCA through the application of the Glucocorticoid Toxicity Index (GTI) version 2.0.

Methods: This retrospective cohort study included patients with a new diagnosis of GCA made in our Centre and classified according to therapy, respectively GCs alone, GCs plus MTX, and GCs plus TCZ. GTI was calculated over a 5-year follow-up period.

Results: We enrolled 150 patients, with a median follow-up of 21 (11-39) months. During this period, 88% experienced at least one GC side effect. The cumulative GC dose was an independent predictor of the GTI-cumulative worsening score (CWS), regardless of treatment group or follow-up time. As first-line therapy, TCZ reduced GC dose by 25% compared to GCs alone, leading to fewer side effects (65% vs. 90%), less GC-induced damage, and no GCA relapses (0% vs. 38%). TCZ also independently protected against relapses, regardless of GC dose or follow-up time. In contrast, MTX did not show similar benefits in any aspect.

Conclusions: GCs represent a cornerstone in GCA therapy, but their cumulative dose correlates with induced damage, as quantified by the GTI. TCZ demonstrated steroid-sparing effect and clinical efficacy in a large real-life cohort.