Improving Readability of Stroke Clinical Trial Consent Forms Using Artificial Intelligence

BACKGROUND: Informed consent forms (ICFs) for clinical trials are often written above the recommended eighth-grade level. We aimed to compare the readability of original ICFs used for National Institutes of Health–funded stroke-related clinical trials with ICFs edited for readability using artificial intelligence. METHODS: Publicly available ICFs associated with National Institutes of Health–funded stroke-related clinical trials were accessed through ClinicalTrials.gov (search period: inception to August 12, 2025). Using ChatGPT-4o, we created a customized Generative Pre-Trained Transformer (GPT) designed to lower the reading level to eighth grade or below while maintaining ICF content. We processed each ICF using this GPT to create edited ICFs. Standard readability metrics, including the Flesch-Kincaid grade level (primary outcome), were compared between original and edited ICFs using paired t tests or the McNemar test (cross-sectional design). We also assessed semantic similarity using the MPNet language model, which produced continuous scores from 0 (no similarity) to 1 (perfect similarity). RESULTS: ICFs were available for 46 stroke trials, including behavioral (n=21), device (n=15), drug (n=5), and other (n=5) intervention types. Mean reading levels were 11.52 for the original and 9.47 for the GPT-edited ICFs using the Flesch-Kincaid grade level ( P <0.001). Only 1 (2%) of the original ICFs and 18 (39%) of the GPT-edited ICFs had a Flesch-Kincaid reading level at or below eighth grade ( P <0.001). Both the Simple Measure of Gobbledygook and Gunning Fog Index favored the GPT-edited ICFs by 1 to 2 grade levels. The Flesch Reading Ease score favored the GPT-edited ICFs by about 8 points. The mean similarity score was 0.85 (SD=0.04). CONCLUSIONS: GPT-edited ICFs achieved a readability reduction of approximately 2 grade levels compared with the original ICFs while preserving high semantic similarity. Customized GPTs may be a useful tool to improve the readability of clinical trial ICFs.