LAUSR

We read with great interest the recently published results from DANBIO registry on switching from originator etanercept (ETA) to the biosimilar SB4.1 The study includes a really impressive number of patients who underwent mandatory switching to SB4, and at first glance the results show a good evidence of efficacy and safety of the procedure. However, in our opinion, how these results may be applied on non-medical switching strategy is rather questionable. A careful reading of the paper raises several concerns related to the demographic and clinical characteristics of switchers and non-switchers, and to the timing of clinical evaluations that may generate misleading biases. First, switchers had longer previous ETA treatment duration and fewer previous bDMARDs compared with non-switchers suggesting a less severe disease. This seems to be confirmed by the baseline lower disease activity both …