Hospital contacts due to hepatobiliary adverse events in >5000 patients with inflammatory joint disease treated with originator or biosimilar etanercept (SB4): an observational nationwide study applying linkage between DANBIO and national registries

Recent international guidelines recommend the use of biosimilar biological drugs on similar terms as their corresponding originators, including switching from a bio-originator to the biosimilar.1 However, the comparative safety of biosimilars in patients with inflammatory joint diseases (IJD) in routine care is still debated.2 In a phase 3 randomised trial among patients with rheumatoid arthritis, biosimilar etanercept (SB4) had slightly more hepatobiliary adverse events compared with the originator (ETN), possibly explained by differences in patients’ comorbid diseases and comedication use.3 The occurrence of, for example, hepatobiliary safety events is likely to differ across indications (due to differences in age, body weight, use of methotrexate, comedication, etc) and has not been explored in etanercept-treated patients with psoriatic arthritis or axial spondyloarthritis.4 In April 2016, a mandatory switch from ETN to SB4 was performed in Denmark to save costs and the 1-year clinical …