Background: To date there is limited data available regarding the general utilization of infliximab and the uptake of its biosimilars in Europe. The nature of the data of PHARMO’s In-patient Pharmacy Database allows for distinction between originator and biosimilar and the assessment of multiple centres and indications at once.
Objectives: To provide an overview of the utilization of originator and biosimilar infliximab in the Netherlands in terms of uptake over time and switching patterns.
Methods: All dispensings for infliximab were selected from the In-patient Pharmacy Database of the PHARMO Database Network from 2002 through 2018. Descriptive analyses were performed in order to characterize initiators of originator and biosimilar infliximab and to characterize patients switching from originator infliximab to biosimilar infliximab and patients not switching.
Results: In total, 3,840 patients with 61,274 infliximab dispensings were identified. 2,496 patients initiated an originator infliximab and 777 patients initiated a biosimilar infliximab. Overall, 57% of the patients was female and mean (± standard deviation [SD]) age was 43.2 (± 17.5) years. Both originators and biosimilars were mostly prescribed by gastroenterologists, followed by internists and rheumatologists. After market authorization of the first biosimilar in 2015 the proportion of new patients initiating the biosimilar increased from 39% in 2015 to 91% in 2018. 704 patients were eligible for switching as they had at least one dispensing of infliximab after 01 January 2015. Among these patients 34% switched. Among switchers, the proportion of females was 60% and mean (±SD) age at index was 45.1 (±16.7) years. Among non-switchers, 55% was female and mean age was 39.8 (±17.0) years. The median (interquartile range [IQR]) time to switch was 1.7 (0.6-2.1) years and switchers were most frequently initiated on infliximab by a rheumatologist (42%), while non-switchers were most frequently initiated by a gastroenterologist (42%).
Conclusions: The results of this large population-based cohort show an increase in biosimilar initiation in daily clinical practice. The number of switchers remains relatively low as non-medical switch is not encouraged in the Netherlands. Complete traceability of originator or biosimilar and indication and expansion of PHARMO’s In-patient Pharmacy Database would increase the applicability and validity of the current results. Linkage to other databases in the PHARMO Database Network would create possibilities to study outcomes among originator and biosimilar infliximab users.