Assessment of Length and Readability of Informed Consent Documents for COVID-19 Vaccine Trials

Importance Informed consent is a fundamental element of research ethics. The COVID-19 vaccine trials are high profile trials that have enrolled more than 100 000 participants. Consent documents must be succinct and understandable to ensure informed voluntary participation. Objective To assess how well informed consent documents of the COVID-19 vaccine trials achieve the ideal of being succinct and understandable, and to create a shorter, more readable document. Design, Setting, and Participants This quality improvement study collected and analyzed the informed consent documents used in 4 COVID-19 vaccine phase III randomized clinical trials to quantitatively assess readability and length and, based on this analysis, created a measurably more accessible informed consent document. Analysis was conducted from October 2020 to January 2021. Main Outcomes and Measures The main outcomes were number of words (measured as word count), time-to-read (measured at reading speeds of 175-300 words per minute), language complexity (measured using Flesch-Kincaid Grade Level assessment), and readability (measured using Flesch Reading Ease Score). Secondary outcomes included clarity of how the placebo group could access the vaccine if it is proven safe and effective. The study also examined the length and readability of an improved consent document. Results The 4 informed consent documents were a mean (range) of 8333 (7821 to 9340) words long, with a mean (range) 35 (32.6 to 38.9) minutes to read at 240 words per minute. All documents exceeded grade 9 language complexity and scored lower than 60 in the formal reading ease metric, which constitutes difficult. Only 1 document specified that participants in the placebo group might receive vaccine. It was possible to write a document in fewer than 3000 words with a grade 7 to 8 reading level and a formal readability score that was not difficult. Conclusions and Relevance These findings suggest that existing COVID-19 vaccine informed consent documents were too long, difficult to read, and exceeded grade 9 in language complexity. It was possible to create a shorter, more readable informed consent document for these trials. This quality improvement study assesses the length, readability, and complexity of informed consent documents for the COVID-19 vaccine phase III randomized clinical trials. Question What are the accessibility and understandability for average audiences of current informed consent documents for the COVID-19 vaccine trials? Findings This quality improvement study of 4 informed consent documents from 4 major COVID-19 vaccine trials found all to be overly long and complex, exceeding a grade 9 language complexity and requiring a mean of 35 minutes to read the entire document. It was possible to reduce the length of the documents by more than 50% and use more broadly understandable language with a grade 7 or 8 reading level. Meaning These findings suggest that informed consent documents may fail to succinctly explain the studies to participants of all reading levels and that it is possible to improve these documents to increase participant accessibility.

Automated summary

The study found that current informed consent documents for COVID-19 vaccine trials are too long and complex, making them difficult to understand. By shortening the length and simplifying the language, the accessibility for participants can be improved.