Almost one-quarter (24%) of patients with rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis who switched from infliximab (Remicade) to its biosimilar CT-P13 discontinued the biosimilar by 6 months, primarily for subjective reasons, Dutch researchers found.
"The discontinuation rate of 24% in the transition group is much higher than expected," the authors commented.
"In our view, the reason for the substantial discontinuation rate in open-label studies is the awareness of both patients and physicians of the transition to the biosimilar," they wrote.
In recent surveys, some patients expressed concerns about the safety and efficacy of biosimilars, suggesting that the lower cost might mean decreased efficacy.
"Pretreatment expectancy" is a recognized influence in treatment outcomes. "Patients' own negative expectations may induce negative symptoms (hyperalgesia or adverse events) during treatment, the so-called nocebo response," the researchers observed. In addition, adverse events that occur following the transition could be incorrectly attributed by patients to the treatment even if they are independent of the medication.