Biological products have contributed to extraordinary advances in disease treatments over the last decade. However, the cost-saving potential of imitator products, so-called biosimilars, is still under-researched in Switzerland. This study aims to assess biosimilars’ prescriptions at treatment initiation and their determinants, as well as biological therapy switches.

The study included all patients who had at least one biosimilar available on the market at the time when they were prescribed a biological product. We analysed longitudinal data for biosimilar prescriptions in Switzerland using descriptive statistics and logistic regression to quantify the associations with individual, pharmaceutical and provider-related variables.

The analysis is based on de-identified claims data of patients with mandatory health insurance at Helsana, one of the Swiss health insurance companies with a substantial enrollee base in mandatory health insurance.

Overall, 18 953 patients receiving at least one biological product between 2016 and 2021 were identified.

We differentiated between initial prescriptions and follow-up prescriptions. Our regression focused on initial prescriptions due to evidence indicating that patients tend to follow the medication prescribed at therapy initiation.

Although biosimilars’ market share was low (28.6%), the number of prescriptions has increased (from 1016 in 2016 to 6976 in 2021). Few patients with medication switches (n=1492, 8.5%) were detected. Increased relative price difference (difference in the price of available biosimilars relative to price of corresponding reference product) was associated with decreased probability of biosimilar prescriptions, whereas male sex, an increase of available imitator drugs on the market, larger packaging sizes, and prescriptions from specialists or physicians in outpatient settings were associated with increased biosimilar use.

The low number of biosimilar prescriptions, despite the proliferating biosimilar market, indicates a high potential for biosimilar diffusion. The findings indicate that patients typically adhere to the therapy options initially chosen and are less inclined to make changes following the initiation of treatment. Our research highlights the need for awareness initiatives to improve understanding among patients and physicians, enabling informed, shared decision-making about biosimilar prescriptions.