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Readability assessment of package leaflets of biosimilars

18 Jan 2019


To assess the degree of readability and the length of the package leaflets of biosimilars.


The package leaflets analysed were downloaded from the European Medicines Agency (EMA) website.


The study sample included the package leaflets written in English of all the biosimilars that were authorised by the EMA on 31 August 2017, and whose content was available via the internet on that date (n=35).


This was a cross-sectional analytical study. The readability of the package leaflets of all biosimilars authorised by the EMA in August 2017 was determined applying the Flesch and Flesch-Kincaid formulas. The influence of the following variables on the readability and length was also analysed: package leaflet section, type of biosimilar, date of first authorisation of the biosimilar and type of medicine.


A considerable variation of the package leaflets length was found (3154±803). The readability of all the package leaflets overtook the recommended value for health-related written materials taking into account Flesch-Kincaid Index, and none of the package leaflets were easy to understand according to the Flesch Index. Statistically significant differences (p<0.05) were observed between the sections of package leaflets in readability indices and length. The most difficult sections to understand were those related with the therapeutic indication of medicine and the possible side effects.


Package leaflets for authorised biosimilars may not fulfil the function for which they were designed. The competent organisations could be informed about the possible negative effect on the use of this type of medicines.

Click here to view the full article which appeared in BMJ Open