Background: Tocilizumab (Actemra) is a humanized antiinterleukin-6 receptor antibody that has been used as a steroid-sparing agent in giant cell arteritis (GCA). Although the clinical effects are well described in GCA, the costeffectiveness of the use of tocilizumab in GCA is ill defined. The purpose of this study was to determine the cost-effectiveness of tocilizumab in GCA compared with prednisone alone. Methods: A retrospective study of 32 patients with biopsyproven GCA comparing prednisone alone (16 patients) and prednisone with tocilizumab (16 patients) was performed. The cost for tocilizumab therapy for 26 weeks with mild and severe side effects (Groups 1 and 2, respectively) and for 52 weeks with mild and severe side effects (Group 3 and 4, respectively) was compared with estimated costs of mild and severe steroid-induced side effects (Groups 5 and 6, respectively). Statistical analysis between groups was conducted using independent sample t tests. Results: Three out of the 4 group combinations of tocilizumab with prednisone demonstrated a statistically significant (P , 0.05) difference in cost compared with prednisone alone for GCA. Group 2 (26-week tocilizumab therapy with severe steroid-induced side effects), with no statically significant difference in price when compared with steroid therapy alone and far fewer side effects, demonstrated the potential use of tocilizumab in GCA therapy. As expected, longer treatment duration with tocilizumab was associated with greater cost. With respect to side effect severity, the number of side effects of steroid therapy was inversely associated with difference in cost between tocilizumab therapy and steroid side effect treatment. Conclusion:This study demonstrates that combination therapy of tocilizumab and prednisone is significantly more expensive than steroids alone with or without accounting for the cost of steroid-induced side effects in treated GCA. The difference in cost between the 2 therapy types is directly related to tocilizumab therapy duration and inversely related to the number or severity of steroid side effects. Patients with GCA who require a shorter duration of steroid therapy and are at risk for a high number of side effects from steroid use may be potential candidates for tocilizumab therapy, from an economic perspective.