Severe Infections in Patients Treated with Tocilizumab for Systemic Diseases Other Than Rheumatoid Arthritis: A Retrospective Multicenter Observational Study.

Objective: This study aimed to describe severe infections in patients treated with tocilizumab for systemic diseases other than rheumatoid arthritis.

Methods: Data from patients receiving at least 2 doses of tocilizumab for systemic diseases other than rheumatoid arthritis between January 1, 2012, and July 1, 2020, in the region Poitou-Charentes (France) were retrospectively collected from medical records. Psoriatic arthritis and systemic juvenile idiopathic arthritis were also excluded as usually treated with similar modalities to rheumatoid arthritis.

Results: Of 37 patients, mainly suffering from giant cell arteritis, 25 patients (68%) had at least 1 infectious event and 15 severe infections occurred in 6 patients (3.2/100 patient-years), mainly bacterial. Lower respiratory tract and skin were the main sites. Severe bacterial infections were associated with a marked biological inflammatory syndrome, even under a cycle of administration of tocilizumab. Two severe zonas and 1 severe diverticulitis occurred. No tuberculosis or viral hepatitis reactivation was observed.

Conclusion: The incidence rate of severe infections was 3.2/100 patient-years and seems lower than that reported in rheumatoid arthritis. C-reactive protein dosage could be helpful for the diagnosis of bacterial infectious adverse events in patients on tocilizumab. Further larger studies are needed to confirm these results to assess potential risk factors for severe infections.