Vulnerable Participants

A “vulnerable participant” is any individual who lacks the ability to fully consent to participate in a study.  There are some groups who have been identified by the federal regulations as “vulnerable populations”: pregnant women and fetuses, minors, prisoners, persons with diminished mental capacity, and those who are educationally or economically disadvantaged.  Pregnant women, prisoners, and minors have specific sections in the federal regulations that provide additional rules for studying these participants. However, instead of broadly classifying various groups as “vulnerable”, the IRB-SBS assess each participant’s ability to consent regardless of whether they fit into the above categories or not.  Instead of labeling one particular group as “at risk," creating the potential for stigmatization and unjustly limiting participation in a study, the IRB-SBS uses an analytical framework to provide each study with a tailored response that is more specific to the needs of the study’s population. As you develop your study, consider the needs of the participants and be aware of issues that may arise regarding their ability to provide full consent. Ultimately the Board will approve studies that demonstrate sensitivity to the participants’ needs, minimize unnecessary risks, and provide them with an appropriate consent procedure.

Inability to consent does not limit participation in a study but instead requires that additional safeguards and consent procedures are followed.The information on this page and in the subsequent sections provides additional information and suggestions for working with various populations. If you have additional questions about your population, please contact our office.



Eight Categories of Vulnerability

The IRB-SBS identifies eight categories where the potential for vulnerability exists in research (modified from National Bioethics Advisory Committee, Ethical and Policy Issues in Research Involving Human Participants. Aug 2001.):

Cognitive or communicative vulnerability

Cognitive or communicative vulnerability occurs when any participant is unable to process, understand, appreciate, and reason through the consent documentation and/or explanations either by mental limitation or language limitation. There are various degrees as to how this may occur. For example, a participant may not be able to read a consent form because of illiteracy, low reading comprehension skills, and/or not speaking the language in which the form is written. If you are targeting a population where this is likely to occur, you need to provide a consent procedure that will accommodate the needs of your participants either by translating the document, writing it in lay language, or discussing the consent. In some cases, you may not be targeting this population, but the issue may arise during a consent session. Do your best to make sure that the participant understands what he or she is consenting to before enrolling them in the study. If you are likely to work with participants where capacity to consent is an issue, it may be necessary for you to include a procedure to assess the participant's capacity to consent. In the case where a participant may not be able to process the full meaning of consent (such as a young child) or is limited by mental defect or disorder, it will be necessary that you obtain consent from a surrogate who is legally responsible for the individual. Although the person may not be able to give full consent, it is still important to involve the person in the consent procedure as to their capability. For more information, see Participants with Diminished Capacity to Consent. 

Institutional vulnerability

Institutional vulnerability occurs when individuals are subject to a formal authority and whose consent may be coerced either directly or indirectly. Examples include prisoners, student/professor relationships, and/or employee/employer relationships. The role of the formal authority in the study will determine the level of perceived or real coercion in the study (i.e. professor studying his students). The solution to this issue is often in the manner in which data are collected and consent is obtained. Using a third party to do so often eliminates any conflicts of interest. However, in the case of prisoners, specific rules are in place regarding their use. For additional guidance, please see Students as ParticipantsEmployees as Participants, and Prisoners as Participants

Deferential vulnerability

Deferential vulnerability occurs when individuals informally subordinate to an authority figure. For example, abuse victims, doctor/patient relationships, and/or husband/wife relationships are all situations where one party may feel obligated to follow the advice of another. These situations require a sensitive recruitment and consent plan where participants have the opportunity to consent voluntarily.

Medical vulnerability

Medical vulnerability occurs when individuals' medical state may cloud their ability to make a decision regarding study participation. The patient may see the research study as a miracle cure to their disease instead of a procedure that has no guarantee for results. Often presenting the study in an environment where the participant is able to understand the full meaning of the study will help to alleviate any misunderstanding.

Economic vulnerability

Economic vulnerability occurs when individuals' economic situation may make them vulnerable to the prospect of free medical care and/or the payments issued for participating in the study. It is important that the payment offered will not encourage an individual to put themselves at a greater risk than they would otherwise. For more information about making payments to participants, please see Payment.

Social vulnerability

Social vulnerability occurs when participants are at risk for discrimination based on race, gender, ethnicity, and age. Researchers may not offer the full explanation in the consent because they feel a participant is not able to comprehend it because of that person’s race, etc. The participant may also be prone to feel discriminated against as well and may not participate as a result of this predisposition. 

Legal vulnerability

Legal vulnerability occurs when participants do not have the legal right to consent or who may be concerned that their consent could put them at risk for legal repercussions. For those who are unable to legally consent, it is important that you obtain consent from a legal representative and in most cases obtain assent from the individual. For those that are concerned about having their legal status compromised by the study, you should take steps to legally protect participants. For example, obtaining a Certificate of Confidentiality for U.S. citizens can protect confidentiality. For some, alternative consent methods may appropriate, such as oral consent.

Study vulnerability

Study vulnerability occurs when participants are made vulnerable by the study’s design. Generally this category refers to participants who are deceived during the study and/or the nature of the study is not revealed to the participant. This can be alleviated by providing full consent and disclosure after the study is completed or whenever a participant withdraws from the study.


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