Author: Donna Lloyd-Jones, Ph.D.
Date: October 13, 2022


In keeping with our goal to publish timely and useful information related to human subjects research, Learn eCORE asked Donna Lloyd-Jones to share her expertise on the importance of health literacy to the research enterprise.

Designing Health Literate Clinical Research

By Donna Lloyd-Jones, Ph.D

October is Health Literacy Month. It’s a good time to consider the role health literacy plays throughout the entire clinical research process—from recruitment and retention to dissemination of findings– to improve the generalizability of clinical research findings, promote health equity, and meet regulatory requirements.

Defining Health Literacy

Historically, most definitions of health literacy focused on the individual, e.g., “the degree to which individuals have the capacity to obtain, process, and understand basic health information and services needed to make appropriate health decisions” (1). However, there’s been a growing trend to acknowledge the role of health care organizations in making health information, services, and research accessible and comprehensible to the public.

For example, Healthy People 2030, an initiative to set goals and objectives to improve the health and well-being of Americans over the coming decade, expanded the definition of health literacy to reflect this new approach (2):

  • Personal health literacy is the degree to which individuals have the ability to find, understand, and use information and services to inform health-related decisions and actions for themselves and others.
  • Organizational health literacy is the degree to which organizations equitably enable individuals to find, understand, and use information and services to inform health-related decisions and actions for themselves and others.

People’s ability to understand health information plays an important role in clinical human subjects research recruitment, access, patient instructions, and patient-reported information.

Rates of Low Health Literacy

About 36 percent of adults in the United States were estimated to have low personal health literacy in a 2003 survey conducted by the U.S. Department of Education that remains the only national data on health literacy in the United States (3).

However, there have been recent assessments of the overall literacy and numeracy skills that are key components of health literacy from the Program for the International Assessment of Adult Competencies. Analysis of its U.S data from 2019-2020 reveal that one in five U.S. adults (21 percent)—or approximately 43.0 million people—possess low literacy skills, meaning that they are unable to complete tasks such as comparing and contrasting information, paraphrasing, or making low-level inferences (4). Nearly one in three U.S. adults (30 percent)—or approximately 62.7 million people—have low numeracy skills (i.e., the ability to access, use, interpret, and communicate mathematical information and ideas) (5).

Thus, clinical researchers are likely to encounter many potential research participants whose ability to comprehend written research materials, such as those in consent documents, are limited.

How Health Literacy Relates to Clinical Research

Employing strategies to reach audiences with low health literacy could allow clinical researchers to more effectively recruit and retain broader study samples that better reflect the populations affected by the conditions they are studying, thereby increasing the generalizability of their findings. This, in turn, will promotes health equity by producing clinical findings relevant to affected populations.

Health Literacy Strategies for Clinical Research

Infusing heath literacy principles into clinical trial research means paying attention to (7):

  • using plain language
  • addressing numeracy
  • employing graphics, images, and clear design principles to enhance visualization of information
  • providing navigation through the research process, and
  • assuring linguistic and cultural competencies in all human subjects research materials and methods.

It also includes:

  • assuring that clinical research materials are comprehensible by the intended audience(s) by developing them in partnership with those audience(s),
  • testing/evaluating participant materials to ensure understandability, and
  • training staff at all levels in how to engage in respectful dialogue with research participants and confirm understanding through techniques such as teaching back.

As an added benefit, these strategies can enhance research participation for everyone—not just those with low health literacy. Even those who have the health literacy skills needed to navigate the complexities of the health care system may find their capacities stressed when they are ill. Thus, the universal adoption of the health literacy strategies noted above are recommended because clinicians and researchers can’t know in advance who may be challenged by complicated health information (8). One study, for example, found that using a simplified consent form that included plain language, short sentences, diagrams, pictures, and bullet points in a cancer trial increased understanding among all participants irrespective of their health literacy level (9).

Health Literacy Best Practices to Use Across the Clinical Trial Life Cycle

The Multi-Regional Clinical Trials Center of Brigham and Women’s Hospital and Harvard (MRCT) has developed tools and resources to guide the application of health literacy best practices at each stage of the clinical trial life cycle. For example, MRCT’s clinical research glossary translates research terms into words that non-researchers can understand. Investigators can use these resources for a variety of research-related tasks.

Research Project Planning: Building trust with communities in which prospective participants live is essential to help overcome negative perceptions of clinical research among underserved communities. Establishing relationships with trusted community leaders and gathering information on community concerns and needs are two valuable strategies for building community trust in the research enterprise.

Participant Recruitment: Prior to formal recruitment, engage the communities from which prospective human subjects research participants will be drawn and educate them about the study. Flyers, social media, ads, websites, recruitment letters and other promotional materials, should be written in plain language with clear formatting, straightforward messaging, and cultural sensitivity. Focus groups can be helpful here in identifying key messages, recruitment channels, and potential barriers, as well as in soliciting feedback on draft materials.

Informed Consent: The U.S. revised Common Rule that went into effect in 2019 require that research consent materials facilitate the prospective subject’s or legally authorized representative’s understanding of the reason why one might or might not want to participate in a study (10). In Europe, the European Union’s General Data Protection Regulation (GDPR) that went into effect in 2018 requires that consent be intelligible and written in plain language.

The Clinical Trials Transformation Initiative (CTTI) recommends thinking beyond a single document to a tiered informed consent process—an ongoing, interactive conversation between each participant and trained staff. In the first tier, the informed consent document should contain only the elements of informed consent required by federal regulation. The second tier should contain additional information, in chapter format, on a range of study-related issues for each study participant to review as deemed necessary. A third tier consisting of a 1-2 page introduction or a summary of the study may be valuable for more complex studies. CTTI also recommends that draft informed consent documents be evaluated using standardized health literacy/plain language assessments, reading level assessments, and/or usability testing with patients similar to those who would be eligible for the study.

A discussion aid for research staff can help them assure that potential participants understand and evaluate the information contained in the informed consent document.

Participant Retention: Throughout the study, the plain language and clear design principles suggested above for recruitment materials should be used to create engaging patient materials for communicating with participants to help keep them engaged and underscore the importance of their continued participation.

Research Results: The U.S. database posts results for all trials funded by the NIH and for other applicable clinical trials. This website includes a checklist with tips for creating a brief summary of clinical trials results that can be readily understood by the general public.

The European Union (European Union Clinical Trials Regulation (EU CTR) 536/2014) has mandated since January 2022 that lay summaries of trial results be provided to all study participants in Europe, as well as to the general public. The EU CTR advises that such lay summaries be written in plain language so that they are understandable and that visualization of content (e.g., the use of infographics for better understanding) is essential.

In summary, attention to health literacy issues will have a positive impact on the conduct of scientifically sound clinical human subjects research that also embodies the ethical principle of justice to include persons most impacted by the research topic.


  1. What is Health Literacy? Centers for Disease Control and Prevention,
  2. Healthy People 2030.
  3. Kutner, M., Greenberg, E., Jin, Y., and Paulsen, C. (2006). The Health Literacy of America’s Adults: Results From the 2003 National Assessment of Adult Literacy (NCES 2006–483). U.S. Department of Education. Washington, DC: National Center for Education Statistics.
  4. National Center for Education Statistics. Data Point. Adult Literacy in the United States. July 2019.
  5. National Center for Education Statistics. Data Point. Adult Numeracy in the United States. September 2020.
  6. Social Determinants of Health, Healthy People 2030.
  7. National Academies of Sciences, Engineering, and Medicine 2020. Health Literacy in Clinical Research: Practice and Impact: Proceedings of a Workshop. Washington, DC: The National Academies Press.
  8. AHRQ Universal Health Literacy Precautions Toolkit, Agency for Healthcare Research and Quality,
  9. Kim, E. J., & Kim, S. H. (2015). Simplification improves understanding of informed consent information in clinical trials regardless of health literacy level. Clinical trials (London, England), 12(3), 232–236.
  10. Hudson, K. L., & Collins, F. S. (2015). Bringing the Common Rule into the 21st Century. The New England journal of medicine, 373(24), 2293–2296.

Resources and Guidance Documents

AHRQ Health Literacy Universal Precautions Toolkit is designed to increase patient understanding of health information at all levels of health literacy. Agency for Healthcare Research and Quality.

CDC Clear Communication Index provides a set of research-based criteria to develop and assess public communication products.

European Medicines Agency 8 Clinical Trial Regulation EU No. 536/2014 requires consistent rules for conducting clinical trials throughout the EU and that information on the authorization, conduct, and results of each trial be made publicly available.

European Union General Data Protection Regulation imposes security and privacy regulations for any organization targeting or collecting data on people in the European Union.

Federal Plain Language Guidelines help writers ensure information is presented clearly.

Health Literacy. Centers for Disease Control and Prevention. Website provide a broad range of resources about health literacy.

Health Literacy in Clinical Research Multi-Regional Clinical Trials Center. Website provides guidance for how to reach audiences with low health literacy at each stage of the clinical research lifecycle.

NIH Clear and Simple website provides guidelines for writing and designing health information for audiences with limited literacy.

Plain Language Checklist for Lay Brief Summaries. website:

Recommendations for Informed Consentfrom the Clinical Trials Transformation Initiative presents guidance for effectively communicating informed consent in clinical research.

About the Author:

Donna Lloyd-Jones, Ph.D., is an independent health communication consultant located in Williamsburg, VA. She has developed health information materials for both lay and professional audiences on behalf of leading federal and state health agencies, taught health communication at the University of Maryland Global Campus, and authored health education textbooks for K-12 schools. Dr. Lloyd-Jones holds a Ph.D. in communication theory and research from Stanford University.

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