Incidence of COVID-19 in patients treated with infliximab compared with patients treated with rituximab

Objective: To determine whether patients with inflammatory autoimmune diseases treated with rituximab (RTX) have more severe forms of COVID-19 compared with patients treated with anticytokine therapies, such as Tumour Necrosis Factor (TNF) inhibitors.

Methods: We included all patients who were on either RTX or infliximab (IFX) in two Swiss cantons during the first wave of the COVID-19 pandemic. We collected self-reported symptoms compatible with COVID-19, PCR-confirmed diagnoses of COVID-19 and the evolution of COVID-19 infections. We computed the raw and propensity score-adjusted incidence of COVID-19 by treatment group.

Results: 190 patients were enrolled, of whom 121 (64%) were in the RTX group and 69 (36%) were in the IFX group. Twenty-one patients (11%) reported symptoms compatible with COVID-19 (RTX: 10, IFX: 11, p=0.14). Among patients with COVID-19 symptoms, four developed severe forms of the disease, with life-threatening pulmonary manifestations requiring intensive mechanical ventilation (RTX: 4 of 10, IFX: 0 of 11, Fisher's exact test p=0.04). The incidence rate of COVID-19 symptoms was 0.73 (95% CI 0.39 to 1.37) cases per 1000 patient-days on RTX vs 1.52 (95% CI 0.82 to 2.85) cases per 1000 patient-days on IFX (crude p=0.10, adjusted p=0.07). The incidence rate of severe COVID-19 was 0.28 (95% CI 0.08 to 0.7.2) cases per 1000 patient-days on RTX compared with null on IFX (95% CI 0.0 to 0.44) (p=0.13). A replication in an independent validation cohort confirmed these findings, with consistent results in the Swiss Clinical Quality Management registry.

Conclusion: While the incidence of symptoms compatible with COVID-19 was overall similar in patients receiving RTX or IFX, the incidence of severe COVID-19 tended to be higher in the RTX group.