Background In the Europe, rituximab (RTX), an anti-CD20 monoclonal antibody, is reserved for patients with rheumatoid arthritis (RA) who have failed initial anti-TNF therapy. There is a concern over whether B-cell depletion and potential resultant hypogammaglobulinaemia may result in an increased risk of serious infections (SI).
Objectives The aim of this study was to determine if RTX influences the risk of SI when used in routine clinical practice.
Methods The British Society for Rheumatology Biologics Register-RA is an ongoing national prospective cohort study of subjects with RA recently started on biologic therapy. Patients who had failed a 1st anti-TNF and were switched to either a 2nd anti-TNF or RTX between 2001-2012 were identified from the study cohort. All patients were followed by physician and patient questionnaires every 6 months for the first 3 years and annual physician questionnaires thereafter, in which data on drug therapy and serious adverse events were reported. Deaths were identified by flagging with UK National Health Service Information Centre. SIs were defined as those requiring intravenous antibiotics and/or hospitalization, or those resulting in death. Subjects were followed until 01/31/2013, the end of the 1st year after the switch, 1st SI, death or treatment discontinuation allowing for a lag window (90 days after 1st missed dose of anti-TNF and 9 months following each course of RTX), whichever came first. The rates of SI in both cohorts were compared using Cox proportional hazards model adjusted by propensity score using inverse probability of treatment weighting (IPTW) (see variables in table).
Results In total, 205 subjects experienced at least one SI in the 1st year of follow-up after the switch of treatment (158 in 3237 anti-TNF treated subjects (2688 person-years (pyrs) and 47 in 1018 RTX treated subjects (866 pyrs)) (Table 1). After adjustment, the risk of SI in patients receiving RTX did not differ from that in patients receiving a 2nd anti-TNF: hazard ratio (HR) for RTX 0.74 (95% CI 0.37, 1.50).
Conclusions Patients receiving RTX after one anti-TNF failure do not appear to have an increased risk of SI during the 1st year of treatment compared to patients receiving a 2nd anti-TNF.
Disclosure of Interest None declared
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