Adverse effect of Pneumocystis Jirovecii infection associated with rituximab therapy for autoimmune disease are more frequently reported in older vs. younger patient.

Introduction: Rituximab is a chimeric anti-CD20 antibody commonly used to treat patients with autoimmune diseases. Such diseases mainly affect young people, but older patients may also be concerned. So far, very little data exist concerning the safety of rituximab in older patients with autoimmune diseases.

Methods: This study was intended to describe the adverse reaction profile of rituximab in patients over 75 years of age treated for autoimmune diseases and to compare such profile to those observed in patients below 75 years of age. Adverse reactions related to rituximab were reported to the French Pharmacovigilance Network. From such reports, a descriptive analysis as well as a disproportionality analysis were performed to identify safety signals.

Results: 1096 reports of rituximab-related adverse reactions reported in France between 2006 and 2019, were included in the study, such as 127 in the older group (>75 years) and 969 in the younger group (<75 years). Infusion reactions were less frequently reported than other adverse drug reaction in older patients (11 vs. 27%, P<0.001). By contrast, a higher rate of opportunistic infection due to Pneumocystis jirovecii was reported in the older subject group (3.9 vs. 0.6%, P<0.001), along with neutropenia (22.8 vs. 9.3%, P<0.0001). These results were confirmed by the disproportionality analysis.

Conclusion: Pneumocystis jirovecii infection was significatively more reported in older patients treated by Rituximab which probably reflects a higher incidence in this population. The use of anti-pneumocystis prophylaxis should be considered in this population.