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.