Table 1 Description of the provotypes presented during the interviews

Provotype 1: Hosting an eIC system

Participants were shown four different interfaces. Each interface mentioned that a certain party is responsible for hosting an eIC system, and thus, for correctly storing participants’ personal data and guaranteeing their privacy. Hosting parties included (1) a pharmaceutical company, (2) the Belgian government, (3) the PI, and (4) the hospital that has been conducting the clinical trial in which the participant has taken part.

Provotype 2: Amount of information about stakeholders’ access to an eIC system

Participants were shown four different interfaces. On each interface, it was mentioned that an eIC system stores participants’ personal data such as their name, address, date of birth, and medication history. Additionally, interfaces included the following messages: (1) “We cannot tell you who has access to your personal data.”, (2) “Only persons with legitimate rights have access to your personal data.”, (3) “The Belgian government has access to your personal data when conducting inspections. The government will conduct inspections if deemed necessary, for example if there is a complaint related to the study. The PI has access to your personal data when consulting your electronic health record. The evaluating ethics committee does not have access to your personal data. The task of the ethics committee is to protect the rights of the participants who take part in a clinical study. They verify if your rights are respected. The sponsor of this study does not have access to your personal data. The sponsor is responsible for the preparation of the research protocol, taking an appropriate insurance, receiving approval for conducting the study of the relevant authorities/ethics committees, and registering the study in a publicly available register.”, and (4) “The Belgian government and the PI have access to your personal data.”.

Provotype 3: Being searchable for future research studies

Participants were shown three different interfaces. On each interface, it was mentioned that an eIC system stores participants’ personal data such as their name, address, date of birth, and medication history. Participants were informed that their data will be shared with (1) physicians all over the world, (2) a specific pharmaceutical company, and (3) physicians of the hospital that has been conducting the clinical trial in which the participant has taken part, and that they could contact them when they need participants for a new research study. All interfaces indicated that participants are able to indicate for which particular type of research (e.g., for research in a particular health condition) they would like to be contacted.

Provotype 4: Being electronically informed about study-related information

Participants were shown one interface on which five pop-up messages appeared one after another. These messages included the following information: “The recruitment of this study has been finished. The study will start soon.” or “New results of the study in which you are taking part are available. Please consult these results.” or “There is a new IC version available. Please consult this new version.”. Some messages appeared twice.

Provotype 5: Contacting the PI during the course of the study

Participants were shown three different interfaces. Interfaces included the following messages: (1) “If you have questions about this clinical study, you can only contact the chatbot. The chatbot is a software program that will help you further.”, (2) “If you have questions about this clinical study, you can only contact the PI via the chat.”, and (3) “If you have questions about this clinical study, you can only set-up a video consultation with the PI”.

Provotype 6: Providing reconsent

Participants were shown three different interfaces. Interfaces included the following messages: (1) “There is a new IC version available which you can consult. You will automatically agree to this version and do not need to take any action.”, (2) “There is a new IC version available which you can consult. The changes are highlighted. If you agree, please sign this version electronically.”, and (3) “There is a new IC version available which you can consult. The changes are highlighted and additional information is provided on why these changes were necessary. If you agree, please sign this version electronically.”.

Provotype 7: Participants’ responsibility when indicating their preferences

Participants were shown two interfaces. On the first interface, it was mentioned that participants could be informed about the further course of the clinical trial via an eIC system, and that they could indicate their preferences regarding the type of information they would like to receive. The second interface included various options participants could choose. Options included: (1) the status of the study, (2) final study results, (3) preliminary study results, (4) results of additional investigations (e.g., blood sampling), and (5) a new IC version.

Provotype 8: Implementation of questions to assess participants’ level of understanding

Participants were shown four different interfaces. Interfaces included the following messages: (1) “Please answer the questions below. You must answer all questions correctly before you can sign the IC. If you need more information to answer a question, please consult the PI. This system will not provide any feedback or additional information on your answers, except whether all questions were answered correctly. If you give an incorrect answer to one or more of the questions, you will be excluded from the study. You get one single attempt.”, (2) “Please answer the questions below. You must answer all questions correctly before you can sign the IC. If you need more information to answer a question, consult the PI. This system will not provide any feedback or additional information on your answers, except whether all questions were answered correctly. You can retry as many times as you want.”, (3) “Please answer the questions below. You must answer all questions correctly before you can sign the IC. If you need more information to answer a question, you can click the ‘Tell me more’ button. For any questions that are answered incorrectly, you will receive additional explanation. You can retry as many times as you want.”, and (4) “Please answer the questions below if you want to get insights in how well you understand the study in which you would like to take part. It is NOT necessary to answer all questions correctly before you can sign the IC. If you need more information to answer a question, you can click the ‘Tell me more’ button. You can retry as many times as you want, or click ‘skip’ to sign immediately.”.