Readability of patient and health care professional targeted dietary supplement leaflets used for diabetes and chronic fatigue syndrome.

OBJECTIVES: The purpose of this study was to assess readability of patient and health care professional targeted dietary supplement (DS) leaflets used for diabetes mellitus (DM) and chronic fatigue syndrome (CFS) with a novel measurement tool and Flesch-Kincaid Grade Level (FKGL).
METHODS: Patient and professional leaflets for DS used to treat DM and CFS from the Natural Medicines Comprehensive Database (NMCD) and Natural Standard (NS) databases were evaluated. Leaflets were analyzed using FKGL and the author-developed health information readability analyzer (HIReA). HIReA integrates lexical, semantic, syntactic, cohesion, and style features and yields values of -1 (very hard) to 1 (very easy).
RESULTS: Patient-targeted leaflets substantially exceeded the consensus readability level (6th grade) as assessed by both FKGL (grade 13.0767) and HIReA (-0.2360). Professional leaflets were similarly more difficult to read as scored by HIReA (-0.7065) and FKGL (grade 14.7429). Most and least difficult-to-read sections in patient leaflets (NS/NMCD) were Related Terms (-0.8863)/Other Names (-0.8146), and Safety Concerns (0.0821)/Scientific Evidence (0.0629), respectively. Overall, leaflets in NS (-0.5721) were more difficult to read than those in NMCD (-0.3704). These differences appeared to be less pronounced when FKGL was used to assess the readability, indicating its lack of preciseness.
CONCLUSIONS: Readability for patient targeted DS leaflets is far more difficult than recommended levels. HIReA is a more precise method to measure readability than FKGL. The disparity between targeted levels of readability and measured levels may contribute to a lack of understanding by patients, with a resulting negative impact on adherence and outcomes.