Infliximab use in the Netherlands: Uptake and characteristics of
originator and biosimilars over time
Abstract
Aims: The objective of this retrospective cohort study was to provide an
overview of the utilization of originator and biosimilar infliximab in
the Netherlands. Methods: All infliximab dispensings were selected from
the PHARMO In-patient Pharmacy Database from 2002-2018. Descriptive
analyses were performed in order to characterise initiators and to
describe switching patterns over time. Results: Overall, 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
age was 43.2 years. Both originators and biosimilars were mostly
prescribed by gastroenterologists, followed by internists and
rheumatologists. After market authorization of the first biosimilar the
proportion of new patients initiating the biosimilar increased from 39%
in 2015 to 91% in 2018. Out of 704 patients eligible for switching 34%
switched. Among switchers, the proportion of females was 60% and mean
age at index was 45.1 years. Among non-switchers, 55% was female and
mean age was 39.8 years. The median time to switch was 1.7 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.