TRIbune Fall 2019 - Has the Revised Common Rule Improved the Readability of Consent Forms?
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Has the Revised Common Rule Improved the Readability of Consent Forms?

September 2019



Since the Nuremberg trials and the Tuskegee study, the international scientific community has recognized that research participants must be protected from abuse. As part of this protection, study teams must ensure that participants are adequately informed about the research. This has led to the development of informed consent forms, which explain the purpose of the research, the procedures involved, and the anticipated risks and benefits of the research.

In the United States, one of the regulations governing informed consent is the Common Rule, Title 45 CFR part 46. Officially, adherence to the Common Rule is only required for government-funded studies, however most institutions conducting research in the United States abide by this regulation. The Common Rule includes requirements that protect vulnerable populations and that ensure that the consent process provides the information needed to make an educated choice about participating in the study.

A participant cannot provide adequate informed consent unless they thoroughly understand the study. Researchers have recently criticized the poor readability of consent forms, stating that they can be overly long and confusing, legal documents that focus more on protecting research teams from liability than on providing adequate information to participants.

Critics of consent form readability often use Flesh-Kincaid Readability scores as an assessment tool. Flesh-Kincaid Readability scores use two formulas developed by Rudolph Flesch and J. Peter Kincaid to quantify the reading difficulty level of a text. The Flesch Reading-Ease test gives a score between 0.0-100.00, with higher scores indicating easier readability. The Flesch-Kincaid Grade Level test scores the readability of a text as a United States school grade level (e.g., eighth grade reading level, twelfth grade reading level).

Multiple studies have noted that research consent forms fail to comply with the official standards for acceptable readability. A 2003 study by Paasche-Orlow, Taylor, and Brancati of sample consent forms from over one hundred medical school websites found that the average Flesh-Kincaid scores of the forms "exceeded the [IRB's] stated standard by 2.8 grade levels."1 Another study in 2017 by Hadden, et al. of over two hundred IRB-approved consent forms found that, while it was recommended by the IRB that consent forms be written at a sixth to eighth grade reading level or lower, over 80% of the consent forms that were reviewed were written at a ninth grade level or higher (up to a thirteenth to fourteenth grade level)2. Similarly:

...a [different] survey by the National Assessment of Adult Literacy reported that the average reading level of US adults is eighth grade or below. A recent review of written consent forms revealed that most are currently written at a 10th grade reading level or higher across all medical specialties.2

The problem of consent form readability was further confirmed in a recent 2019 study that analyzed three hundred and ninety-nine consent forms from FDA-approved investigational device exemption studies that took place in 2015-2016. The study found that, on average, the readability of consent forms exceeded the recommended level. The FDA recommends that consent forms should be written at a sixth to eighth grade reading level, however the average reading level for the consent forms analyzed in the study was tenth grade to college reading level.3

The Revised Common Rule, which went into full effect on January 21, 2019, contains several revisions that may increase poor readability of consent forms. To comply with the new requirements, consent forms must now include information on whether biospecimens will be used in Whole Genome Sequencing (WGS), whether participants will be asked to provide additional consent for use of their biospecimens in future research, and whether participants will share in the commercial profits from use of their biospecimens. These revisions add to the length of consent forms and, arguably, make them more difficult to understand (for example, many potential participants are unfamiliar with WGS).

Nonetheless, other revisions to the Revised Common Rule include two updates specifically designed to improve the readability of research consent forms. Title 45 CFR part 46.116(a)(3) states that, in general, consent forms must be written "in language understandable to the subject or the legally authorized representative." Additionally, 45 CFR 46.116(a)(5)(i) requires consent forms to:

...begin with a concise and focused presentation of the key information that is most likely to assist a prospective subject or legally authorized representative in understanding the reasons why one might or might not want to participate in the research. This part of the informed consent must be organized and presented in a way that facilitates comprehension.

Experts in human subject protection ask if the implementation of the Revised Common Rule has improved the readability of consent forms. To answer this question, TRI specialists reviewed twenty consent forms from federally funded clinical trials posted on the website. The consent forms came from studies dated after the Revised Common Rule went into effect on January 21, 2019 and were evaluated using the Flesch Reading-Ease test and the Flesch-Kincaid Grade Level test. Additionally, the Key Information sections from the consent forms were evaluated for readability, since these sections must be written to "facilitate comprehension."

The results of the analysis suggest that consent form readability has not improved since the implementation of the Revised Common Rule. The average readability score of the reviewed consent forms was 47.6 (median 49) with an average grade level of 11.2 (median 11.1). The Key Information sections of the consent forms scored similarly, with an average readability score of 47.2 (median 43.9) and a grade level of 11.5 (median 12.1).

These results indicate that the implementation of the Revised Common Rule has not improved consent form readability. This may be due to the contradiction that the Revised Common Rule requires improved readability of consent forms, but additionally requires the inclusion of technical information that is challenging to convey in simple, easily understandable language. Technical information may sometimes be included in consent forms to meet legal requirements; however, this information is often not communicated in lay language. Perhaps study team members have not yet adjusted to the Revised Common Rule: as time goes on, study teams may learn to present the newly required technical information in a more readable format. The addition of a Key Information section to concisely summarize the consent form does not appear to improve comprehension since, as noted, the readability of the Key Information section was not significantly different than the readability of the information overall. Again, in time the study teams may find better ways to present the Key Information section in a more readable manner. Follow-up studies will be needed to see if consent form readability improves over time, as researchers adapt to the new requirements.

What can be done now to improve the readability of consent forms? One recommendation is to follow best practice guidelines and adopt toolkits for plain language, such as those published by the Centers for Disease Control and Prevention (CDC)4, National Institutes of Health (NIH)5, Centers for Medicare & Medicaid Services (CMS)6, and Agency for Healthcare Research and Quality (AHRQ)7. Successful adoption of these guidelines and toolkits will eliminate technical jargon and implement a short, simple sentence structure in consent forms. An example of this is providing a simple, lay language explanation of Whole Genome Sequencing, when applicable. The study by Hadden, et al. found that implementing plain language tools and trainings improved the average readability of consent forms from a tenth grade level to an eighth grade level.2

The Human Subject Protection (HSP) Team at TRI understands the importance of improving the readability of consent forms. Consistent with the Revised Common Rule and based on best practice guidelines and toolkits, the HSP Team analyzes consent forms to ensure they are written in a language and at a reading level that is understandable for the intended study population, and advises clients on how to improve readability when appropriate. Additionally, TRI provides expertise and consultation on consent form regulations, guidelines, development, and operations.


  1. Paasche-Orlow, M. K, Taylor, H. A., and Brancati, F. L. (2003). Readability standards for informed-consent forms as compared with actual readability. New England Journal of Medicine no. 348: 721-726.

  2. Hadden, K. B., Prince, L. Y., Moore, T. D., James, L. P., Holland, J. R., and Trudeau, C. R. (2017). Improving readability of informed consents for research at an academic medical institution. Journal of Clinical and Translational Science 1: 361-365.

  3. Santel, F., Bah, I., Kim, K., Lin, J., McCracken, J., and Teme, A. (2019). A survey of informed consents from FDA's center for devices and radiological health. Contemporary Clinical Trials: 105831.

  4. Centers for Disease Control and Prevention. (2016). Plain language materials and resources. Retrieved from

  5. National Institutes of Health. (2016). Plain language: Getting started or brushing up. Retrieved from

  6. Centers for Medicare & Medicaid Services. (2012). Toolkit for making written material clear and effective. Retrieved from

  7. Agency for Healthcare Research and Quality. (2019). Informed consent and authorization toolkit. Retrieved from

About the Author

Etan Kuperberg, MS, MA is a Human Subject Protection Specialist. He has several years of professional experience in health policy and bioethics.






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