Patients taking the B-cell depleting agent rituximab are at eight times greater risk of being hospitalised with COVID-19 than those taking other biologics, new research has found.

The findings, published in the Annals of the Rheumatic Diseases, lend further weight to evidence showing an increased risk of severe COVID-19 outcomes in patients receiving B-cell targeted therapy.

For the study, researchers assessed 1,116 patients with inflammatory arthritides treated in day hospitals with the intravenous biological agents rituximab (392), abatacept (105), infliximab (449) or tocilizumab (170) across seven clinical centres in France.

Data, collected from September 2019 to January 2021, showed 10 cases of severe COVID-19, of which 9 occurred in patients treated with rituximab (2.3% of rituximab-treated patients) and 1 in a patient given infliximab (0.1% of patients treated with biological agents other than rituximab, 0.2% of patients treated with infliximab).

In multivariate analyses rituximab was the only factor associated with risk of hospitalised COVID-19, with an 8 times increased risk versus other biologic agents, the researchers noted.

While the low number of events and the number of covariates in the study “limit the robustness of the statistical analysis”, the researchers said that on the back of their findings IA patients receiving rituximab “should be prioritised for vaccination against SARS-CoV-2, sufficiently in advance of treatment infusion/reinfusion”.

But Dr Marwan Bukhari, Consultant Rheumatologist and Editor of Rheumatology, also expects there to be wider implications from the study’s findings, which could fuel patient concerns over treatment with rituximab during the pandemic.

“Patients being treated with rituximab are now going to start deferring their next dose because of this concern, [which means] managing their RA will become more difficult,” he told the limbic.

“Less patients will be offered this effective treatment going forward as the concerns about COVID outweigh the management of RA, and B cell therapy is now going to be further up the treatment pathway than before,” he noted.

In response to enquiries from the limbic, a spokesperson for the British Society for Rheumatology said that “all patients should be encouraged to receive a COVID-19 vaccine, regardless of treatment regimen or underlying diagnosis.

“As per our guidance, based on the JCVI recommendations, nearly all rheumatology patients (aside from those solely on hydroxychloroquine or sulfasalazine), should receive a third dose. The guidance is specific with respect to certain drugs and the timings of when the patient has had their previous injections.

“As such, clinicians need to know the following information in order to make an informed decision: what medication the patient is on, and when the patient had their vaccine and what medication they were on at that time.”