Ethical research on detained persons remains limited, including research on informed consent. This study aimed to fill in this research gap and compared audio-visual and paper-based materials for a one-time general informed consent for research in prison, using a randomized design. The primary outcome was whether participants sign the inform consent. Secondary outcomes included understanding, evaluation, and time to read/watch the informed consent.

Detained persons constitute a very vulnerable and perhaps reluctant to share their medical data. In particular, it is crucial to ensure that these persons, deprived of their liberty, understand that their consent is voluntary and that a refusal will not have any consequence on their treatment or care. In other words, it is necessary to ensure that consent is informed. In a historical context of non-ethical research using detained persons, this is a crucial issue. However, while detained persons are now protected from various forms of abuse, this may have had the consequence of reducing research involving them, to the detriment of understanding their characteristics and vulnerabilities.

A general consent for research will encourage research on prison populations by facilitating access to their medical data in order to study and reduce health disparities, for this population with multiple somatic and psychiatric comorbidities.

Our main questions are:

Q1. What is the acceptability rate of general consent for research in detained persons? Q2. What are the characteristics (socio-demographic and medical) of detained person who refuse to give their consent? Q3. Which material (paper-based or video) is more effective?

To answer these research question, we will use an exploratory randomized cross-sectional trial, conducted in an adult pre-trial prison and a juvenile detention center. Participants will be randomly assigned to read or watch information about informed consent, stratified on the prison. In both prisons, the study will take place in the prison medical unit.

This project is aimed to improve general consent, which contributes to reducing inequalities in documentation on health status, and ultimately, health inequalities.

Inclusion Criteria:

• to be18 years old or more in the adult prison and 14 years old or more in the juvenile detention center
• to be able to communicate in one of the languages of the study material
• to agree to participate in this study.

Exclusion Criteria:

• presence of an acute psychiatric problem preventing the person from participating in the study

The datasets are not publicly available due their sensitive nature (detained persons) but are available from the corresponding author on reasonable request.