Using secure WhatsApp-based digital recruitment as an intervention in prostate cancer research with black men

This paper describes the development and implementation of a secure, community-centred digital system as an intervention to share prostate cancer risk information among Black men in southeast Wales. In this study, the term Black men is used to refer to men of Somali and African Caribbean heritage. The system was designed to support culturally and linguistically appropriate participation. Recruitment was facilitated by two community co-applicants using project-funded smartphones and WhatsApp Business accounts to disseminate co-created prostate cancer risk messages, link to external prostate cancer risk checker and link to an evaluation survey, within closed community groups. Participants accessed the survey through a custom landing page that verified mobile numbers via CAPTCHA and unique access codes distributed using TextGlobal. After verification, participants selected their preferred language (English or Somali) to view participant information sheets and consent forms. Submitted consent data were encrypted and securely stored on university servers, with cross-referenced verification ensuring integrity. These measures upheld core digital security principles: protecting access to the WhatsApp groups to invited participants, controlling survey access, protecting the confidentiality and accuracy of consent data through encryption, and maintaining secure storage. A privacy risk assessment using the LINDDUN GO framework identified and mitigated vulnerabilities, including risks of data disclosure, unnecessary processing, and regulatory non-compliance. This paper presents a replicable approach for integrating community engagement with privacy-by-design principles in digital health research. It demonstrates how participatory digital systems can enhance inclusivity and trust while upholding data protection, offering practical guidance for researchers designing secure, culturally informed digital methodologies.