BackgroundDecentralisation of healthcare budgets and issuance of local guidelines means that the use of biosimilars can vary by region within a particular country, for example between the 21 counties of Sweden.ObjectivesThis study aimed to analyse the county-level market dynamics of biosimilar and originator infliximab, which are hospital products, and to examine how local policy measures and practices, in addition to national policy, influenced market dynamics.MethodsWe first conducted a literature review on (biosimilar) policies in Sweden, then analysed market data provided by IQVIA™ on uptake of originator and biosimilar infliximab within the different counties (Q2 2012 to Q4 2017), including discounts from (tender) contracts. Biosimilar market shares were calculated with volume data (measured as defined daily doses [DDDs]). We then discussed our findings in semi-structured interviews with the national pricing and reimbursement agency, key experts within the county councils of Skåne, Västra Götaland, and Stockholm, and an industry representative.ResultsMarket shares of biosimilar infliximab vary widely between counties (range 18–96% in 2017). The initial uptake of biosimilar infliximab was slow and variable, with abrupt increments in biosimilar market shares coinciding with expiration of contracts for the originator product. Different approaches taken by counties to achieve a low cost per DDD of infliximab were identified, i.e., a rapid switch to the biosimilar (Skåne), a delayed switch to the biosimilar (Stockholm), or no switch to the biosimilar when a favourable price on the originator product could be obtained (Västra Götaland). Quantitative analysis showed that 59% of the variability in biosimilar market shares could be explained by the relative difference in discounted price between the biosimilar and the originator product. In addition, qualitative analysis indicated the presence of key opinion leaders, local guidelines and initiatives, and whose budget it affects as drivers in the decision-making process.ConclusionsVariations in the market share of biosimilar infliximab between the Swedish counties is largely explained by the discounted price difference between biosimilar and originator product, and counties used different strategies to leverage such biosimilar competition. Additionally, the presence of key opinion leaders, local guidelines and gainsharing arrangements appeared to play a role in infliximab market dynamics in counties.