Languages for different health information readers: multitrait-multimethod content analysis of Cochrane systematic reviews textual summary formats

BACKGROUND: Although subjective expressions and linguistic fluency have been shown as important factors in processing and interpreting textual facts, analyses of these traits in textual health information for different audiences are lacking. We analyzed the readability and linguistic psychological and emotional characteristics of different textual summary formats of Cochrane systematic reviews. METHODS: We performed a multitrait-multimethod cross-sectional study of Press releases available at Cochrane web site (n = 162) and corresponding Scientific abstracts (n = 158), Cochrane Clinical Answers (n = 35) and Plain language summaries in English (n = 156), French (n = 101), German (n = 41) and Croatian (n = 156). We used SMOG index to assess text readability of all text formats, and natural language processing tools (IBM Watson Tone Analyzer, Stanford NLP Sentiment Analysis and Linguistic Inquiry and Word Count) to examine the affective states and subjective information in texts of Scientific abstracts, Plain language summaries and Press releases. RESULTS: All text formats had low readability, with SMOG index ranging from a median of 15.6 (95% confidence interval (CI) 15.3–15.9) for Scientific abstracts to 14.7 (95% CI 14.4–15.0) for Plain language summaries. In all text formats, “Sadness” was the most dominantly perceived emotional tone and the style of writing was perceived as “Analytical” and “Tentative”. At the psychological level, all text formats exhibited the predominant “Openness” tone, and Press releases scored higher on the scales of “Conscientiousness”, “Agreeableness” and “Emotional range”. Press releases had significantly higher scores than Scientific abstracts and Plain language summaries on the dimensions of “Clout”, and “Emotional tone”. CONCLUSIONS: Although the readability of Plain language summaries was higher than that of text formats targeting more expert audiences, the required literacy was much higher than the recommended US 6th grade level. The language of Press releases was generally more engaging than that of Scientific abstracts and Plain language summaries, which are written by the authors of systematic reviews. Preparation of textual summaries about health evidence for different audiences should take into account readers’ subjective experiences to encourage cognitive processing and reaction to the provided information. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12874-019-0716-x) contains supplementary material, which is available to authorized users.