Improvement and evaluation of readability of Japanese health information texts: An experiment on the ease of reading and understanding written texts on disease

Purpose: The present study comprehensively examined ways of improving and evaluating the readability of Japanese health information texts. Methods: The author assessed the improvement and evaluation of a text written by a medical doctor for patients and the general public regarding chronic suppurative otitis media. First, two different Japanese texts were prepared according to three differing readability factors (syntax, vocabulary, and text structure) and the differences between the three texts including the original were verified. Second, 91 college students were assigned one of the three texts and asked to answer a web survey. Readability was assessed using the time taken to read the text, and comprehension was assessed by a multiple-choice test. Comments on the readability of the text were also collected. Results: Modified Text A with explanations of medical terms in parentheses was more understandable but more difficult to read. Modified Text B, which replaced medical terms with general vocabulary and consolidated the text structure, was more readable but less understandable. Experience of the disease affected the readability. The following conclusions were drawn: 1) syntactic factors contributed to the impression of ease of reading, but conflicted with other factors; 2) medical vocabulary should be replaced with general vocabulary or accompanied by explanations in phrases; 3) the effect of the text's structure on comprehension was not clear due to the problems of improvement and evaluation methods; 4) some human factors should be considered when making the evaluation; and 5) valid comprehension tests are challenging.