Objectives To compare the incidence of serious infection (SI) across biologic drugs used to treat rheumatoid arthritis (RA) using data from the British Society for Rheumatology Biologics Register for Rheumatoid Arthritis (BSRBR-RA).
Methods The BSRBR-RA is a prospective observational cohort study. This analysis included patients with RA starting a new biologic. The primary outcome was SI defined as an infectious event requiring admission to hospital, intravenous antibiotics or resulting in death. Event rates were calculated and compared across biologics using Cox proportional hazards with adjustment for potential confounders. Secondary outcomes were the rate of infection by organ class and 30-day mortality following infection.
Results This analysis included 19 282 patients with 46 771 years of follow-up. The incidence of SI was 5.51 cases per 100 patient years for the entire cohort (95% CI 5.29 to 5.71). Compared with etanercept, tocilizumab had a higher risk of SI (HR 1.22, 95% CI 1.02 to 1.47) and certolizumab pegol a lower risk of SI (HR 0.75, 95% CI 0.58 to 0.97) in the fully adjusted model. The 30-day mortality following SI was 10.4% (95% CI 9.2% to 11.6%).
Conclusions The rate of SI was lower with certolizumab pegol than etanercept in the primary analysis but the result was no longer significant in several sensitivity analyses performed suggesting residual confounding may account for the observed difference. From these results, it would be wrong to conclude that certolizumab pegol has a lower rate of SI than other biologics; however, the risk does not appear to be significantly higher as has previously been suggested.
- rheumatoid arthritis
- dmards (biologic)
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Handling editor Josef S Smolen
Contributors All authors were involved in the design and statistical analysis of the study as well as manuscript drafting and gave approval to the final version.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests The BSR commissioned the BSRBR-RA as a UK-wide national project to investigate the safety of biological agents in routine medical practice. BSR receives restricted income from UK pharmaceutical companies, presently Abbvie, Celltrion, Hospira, Pfizer, UCB and Roche, and in the past Swedish Orphan Biovitrum and Merck. This income finances a wholly separate contract between the BSR and the University of Manchester. The pharmaceutical company funders had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript and decision to submit the manuscript for publication. KH has received honoraria from Pfizer and Abbvie (<US$10 000). JG has received honoraria for speaking or attending conferences from Pfizer, BMS, UCB and Celgene (<US$10 000).
Patient consent Not required.
Ethics approval The study was approved by the North-West Multicentre Research Ethics Committee (MREC 00/8/053, IRAS: 64202).
Provenance and peer review Not commissioned; externally peer reviewed.
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