Background: Package inserts that accompany medicines are a common source of information aimed at patients and should match patient abilities in terms of readability.
Objective: Our objective was to determine the degree of readability of the package inserts for biological medicinal products commercially available in 2007 and compare them with the readability of the same package inserts in 2010.
Methods: A total of 33 package inserts were selected and classified into five groups according to the type of medicine: monoclonal antibody-based products, cytokines, therapeutic enzymes, recombinant blood factors and other blood-related products, and recombinant hormones. The package inserts were downloaded from the European Medicines Agency website in 2007 and 2010. Readability was evaluated for the entire text of five of the six sections of the package inserts and for the 'Annex' when there was one. Three readability formulas were used: SMOG (Simple Measure of Gobbledygook) grade, Flesh-Kincaid grade level, and Szigriszt's perspicuity index.
Results: No significant differences were found between the readability results for the 2007 package inserts and those from 2010 according to any of the three readability indices studied (p>0.05). However, there were significant differences (p<0.05) between the readability scores of the sections of the package inserts in both 2007 and 2010. The readability of the package inserts was above the recommended sixth grade reading level (ages 11-12) and may lead to difficulties of understanding for people with limited literacy.
Conclusions: All the sections should be easy to read and, therefore, the readability of the medicine package inserts studied should be improved.