Objectives Past studies have reported conflicting rates of venous thrombotic events (VTEs) in rheumatoid arthritis (RA). The current study aimed to compare (1) the rates of VTEs in patients with RA treated with anti-tumour necrosis factor (anti-TNF) therapy versus those treated with non-biological disease-modifying antirheumatic drugs (nbDMARDs) alone and (2) the rates between each individual anti-TNF agent and nbDMARDs.
Methods Using data from the British Society for Rheumatology Biologics Register, a national prospective observational cohort study of biological safety in patients with RA, the authors compared the incidence of VTEs between 11 881 anti-TNF- and 3673 nbDMARD-treated patients. Analysis was limited to the first VTE per person. HRs were calculated using Cox modelling. Adjustment was made for potential confounders including surgery performed during follow-up.
Results A total of 196 first VTEs were reported (151 anti-TNF, 45 nbDMARD). Overall there was no difference in the rates of VTEs between anti-TNF- and nbDMARD-treated patients (adjusted HR 0.8 (95% CI 0.5 to 1.5)). The risk was similar across all anti-TNF agents. Rates of postoperative VTEs did not significantly differ between groups.
Conclusions These data suggest that anti-TNF therapy is not associated with an increased risk of VTEs in RA patients.
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Funding The BSR commissioned the BSRBR as a UK-wide national project to investigate the safety of biologic agents in routine medical practice. BSR receives restricted income from UK pharmaceutical companies, presently Abbott Laboratories, Amgen, Schering Plough (now MSD) and Wyeth Pharmaceuticals (now Pfizer). This income finances a wholly separate contract between the BSR and the University of Manchester who provide and run the BSRBR data collection, management and analysis services. The principal investigators and their team have full academic freedom and are able to work independently of pharmaceutical industry influence. All decisions concerning analyses, interpretation and publication are made autonomously of any industrial contribution.
Competing interests DPMS and KLH are principal investigators on the BSRBR. BSR receives restricted income from UK pharmaceutical companies, presently Abbott Laboratories, Biovitrum, Merck Sharp & Dohme, Pfizer and Roche. This income finances a wholly separate contract between the BSR and the University of Manchester. The principal investigators and their team have full academic freedom and are able to work independently of pharmaceutical industry influence. All decisions concerning analyses, interpretation and publication are made autonomously of any industrial contribution. Members of the Manchester team, BSR trustees, committee members and staff complete an annual declaration in relation to conflicts of interest. The authors declare no other conflicts of interest.
Ethics approval This study was obtained in December 2000 from the Multicentre Research Ethics Committee (MREC) for the Northwest of England.
Provenance and peer review Not commissioned; externally peer reviewed.
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