Using plain language to communicate with clinical trials participants: comparison of readability calculators

It is important that patient-facing clinical trial information is easily understood by potential trial participants, active trial participants, family members, friends and carers. The readability of a document refers to its typographic and linguistic characteristics that allow the text to be read and comprehended and it is recommended that healthcare providers aim that all information disseminated to the lay public be at a suitable readability level. Whilst there are established readability calculators for literature, there is no standard for health information. Several readability calculators are available that aid in the analysis of a text, URL or website's readability, however, to date there has been no head-to-head comparison of these. Five readability calculators were compared, including four online realtime calculators, (i) Readable (www.readable.com), (ii) www.webfx.com, (iii) www.datayze.com and (iv) www.online-utility.org, as well as the PC-based analyzer Microsoft Word (Microsoft Corp., USA). Three categories of text information were analysed, including (i) childrens' fairy tales (n = 20) (ii) scientific reports (n = 20) from BBC News websites and (iii) scientific abstracts (n = 20). This study demonstrated that varying scores were obtained by using different readability calculators. Based on these data in combination with issues including availability and ease-of-use, we advocate the use of Readable or Microsoft Word software to aid in the preparation of patient-facing clinical trial information. Clinical trial networks should now consider the need for standardisation of readability calculators and provide guidance to stakeholders so that readability of materials may be improved in a standardised and uniform manner.