Objective: Patients may hold negative perceptions towards biosimilars which can create barriers to their uptake. Physicians also report uncertainty in how best to explain biosimilars. The aim of this study was to measure the effect of differently framed explanations on patients’ perceptions of and willingness to change to a biosimilar in a hypothetical drug switch. Methods: Ninety‐six patients with rheumatic diseases taking an originator biologic were randomised to receive one of four biosimilar explanations ‐ positive framing with and without an analogy, and negative framing with and without an analogy. Willingness to switch to a biosimilar, perceptions about biosimilars, and the effectiveness of the explanation were measured after the information delivery. Results: Positive framing led to more participants being willing to switch (67%) than negative framing (46%). Framing significantly predicted willingness to switch to a biosimilar, with participants in the positive framing group being 2.36 times more willing to switch (P = 0.041). The positive framing group also reported significantly greater perceived efficacy of biosimilars (P = 0.046), and thought the explanation was more convincing (P = 0.030). The analogy did not enhance willingness to switch or understanding (P > 0.05). Conclusion: Positive framing can improve perceptions of and willingness to switch to a biosimilar in patients currently taking biologic treatments.
