Risk factors for infection in rheumatoid arthritis patients treated with tocilizumab: an observational study...

Infections remain a major safety concern in patients with rheumatoid arthritis (RA) receiving tocilizumab (TCZ). This study evaluated clinical risk factors for clinically significant infections in a real-world cohort of TCZ-treated patients with RA.

We conducted a retrospective single-center cohort study including 207 patients with RA who received TCZ. Follow-up continued until infection, loss to follow-up, or 6 months after TCZ discontinuation. Clinically significant infections were defined as events requiring antibiotics, antivirals, or hospitalization. Baseline clinical characteristics, comorbidities, and concomitant medications were analyzed. Multivariable Cox proportional hazards models were used to evaluate factors associated with infection. To address potential confounding by indication, inverse probability of treatment weighting (IPTW) based on propensity scores was performed as a sensitivity analysis.

Among 207 patients, 58 (28.0%) developed at least one clinically significant infection during follow-up. Respiratory tract infections were the most common (82.8%), followed by urinary tract infections (8.6%). In the multivariable Cox model adjusted for disease duration, methotrexate use, and glucocorticoid dose, concomitant hydroxychloroquine (HCQ) use was associated with a lower observed hazard of infection (HR = 0.546, 95% CI 0.306-0.975; P = 0.041). This association remained directionally consistent in the bootstrap-validated IPTW analysis (median weighted HR = 0.583, 95% CI 0.301-0.989).

In this real-world cohort of TCZ-treated patients with RA, concomitant HCQ use was associated with a lower observed risk of clinically significant infection. These findings may help refine infection risk stratification but should be interpreted as hypothesis-generating because of the observational study design. Keypoints • Infections remain an important safety concern for patients with rheumatoid arthritis receiving tocilizumab in real-world practice. • This retrospective cohort study evaluated clinical predictors of clinically significant infections during and shortly after tocilizumab therapy. • HCQ use was associated with a lower observed hazard of infection in the multivariable analysis, and this association was directionally consistent in the IPTW-weighted analysis. • Given the observational design, this association should be interpreted cautiously and confirmed in prospective studies.