Assessing reading levels of health information: uses and limitations of flesch formula

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.