Serious infection during etanercept, infliximab and adalimumab therapy for rheumatoid arthritis: A literature review

The purpose of this review is to establish whether there is a significantly increased incidence of serious infections during treatment for rheumatoid arthritis (RA) with etanercept, infliximab or adalimumab, to determine the background risk of serious infection in RA patients without treatment with any biological therapy and to ascertain which organisms are involved in serious infections in RA patients while being treated with etanercept, infliximab or adalimumab. Randomised controlled trials (RCTs), meta-analyses of RCTs, Cochrane reviews, national registry articles and case reports were identified using PubMed/MEDLINE, The Cochrane Library and Google Scholar. The medical subject heading rheumatoid arthritis was combined with serious infection or infection or adverse drug events with each of the three reference biological therapies separately: etanercept, infliximab and adalimumab. These electronic searches were limited to human studies, adult studies, those published in the last 10years (2004-14) and in the English language. Studies which involved the tumor necrosis factor- inhibitors certolizumab pegol or golimumab were excluded. The background risk of serious infection appears to be approximately two-fold more than non-RA patients before any treatment with biological therapy. The national registries, which may represent the typical RA patient more accurately than clinical trials, suggest a small but significantly increased incidence of serious infection ranging 1.2-2.78 times that of control (treatment with methotrexate). Mycobacteria spp., Staphyloccus aureus, Listeria monocytogenes, Varicella zoster virus and Leishmania species (spp.) repeatedly appear in the case report literature and should be in the mind of the clinician faced with a serious infection in a RA patient with an unknown pathogen who is being treated with either etanercept, infliximab or adalimumab.