Assessing Reading Levels of Health Information: Uses and Limitations of Flesch Formula

Background: Written health information is commonly used by health-care professionals (HCPs) to inform and assess patients in clinical practice. With growing self-management of many health conditions and increased information seeking behavior among patients, there is a greater stress on HCPs and researchers to develop and implement readable and understandable health information. Readability formulas such as Flesch Reading Ease (FRE) and Flesch-Kincaid Reading Grade Level (FKRGL) are commonly used by researchers and HCPs to assess if health information is reading grade appropriate for patients. Purpose: In this article, we critically analyze the role and credibility of Flesch formula in assessing the reading level of written health information. Discussion: FRE and FKRGL assign a grade level by measuring semantic and syntactic difficulty. They serve as a simple tool that provides some information about the potential literacy difficulty of written health information. However, health information documents often involve complex medical words and may incorporate pictures and tables to improve the legibility. In their assessments, FRE and FKRGL do not take into account (1) document factors (layout, pictures and charts, color, font, spacing, legibility, and grammar), (2) person factors (education level, comprehension, health literacy, motivation, prior knowledge, information needs, anxiety levels), and (3) style of writing (cultural sensitivity, comprehensiveness, and appropriateness), and thus, inadequately assess reading level. New readability measures incorporate pictures and use complex algorithms to assess reading level but are only moderately used in health-care research and not in clinical practice. Future research needs to develop generic and disease-specific readability measures to evaluate comprehension of a written document based on individuals' literacy levels, cultural background, and knowledge of disease.