Comparison of Four Readability Indices to Analyze Informed Consent Documents

The US National Library of Medicine defines Health Literacy as “ The degree to which individuals have the capacity to obtain, process, and understand basic health information and services needed to make appropriate health decisions.” . Low health literacy patients have trouble navigating the health care system and following both preventive and treatment care instructions. The Patient Protection and Affordable Care Act (Obamacare) extends health insurance to 32 million lower-income children and adults, a population disproportionately affected by low health literacy. To help ensure readability, documents should be written at a US 8^th grade or less reading level. Objective:  To compare the utility of four common readability test instruments,  the Coleman Liau (CL), Automated Readability Index (ARI), Flesch-Kinkaid (FK), and SMOG  to analyze online informed consent documents (ICDs) for readability expressed in terms of  US  grade levels . All ICDs were limited to describing only Endodontic treatment. Method:  Fifty online ICDs downloaded from US dental practice websites were analyzed by each of the four readability instruments.  For each test instrument,  Mean & Std. Dev. index values (in grade levels) were calculated for each downloaded ICD. Result: The composite overall readability findings for all 50 ICDs, by index in ascending order, were: FK (13.16,  ±1.97), ARI (13.54, ± 2.61), CL (13.93, ± 1.44) and SMOG (14.40  ± 1.53).  Conclusion: All four test instruments purport to measure readability, yet when analyzing identical Endodontic ICDs, they differ in their assessments. The FK analysis appears to provide lower and the SMOG higher grade level scores. Readability test instruments employ slightly different algorithms for determining readability scores. Document content, punctuation, and formatting may play a significant role. Endodontists and other clinicians are advised to be sensitive to slight differences in common readability test instruments when developing  ICDs and other documents with ≤8^th grade readability levels.