Introduction Oral Pre-Exposure prophylaxis (PrEP) with Truvada is a promising tool to reduce the number of HIV infections among men who have sex with men (MSM). With growing scientific interest in non-daily PrEP regimens (e.g. event-driven) assessing PrEP adherence has become more challenging. The aim was to develop, use and optimise an online tool to monitor PrEP adherence.

Methods In a first phase, an interdisciplinary team developed a secure web-based tool to collect data on adherence within a Belgian PrEP demonstration project (Be-PrEP-ared), involving 200 MSM using daily or event-driven PrEP or discontinuing PrEP use. The online diary was piloted before study implementation, and slightly adapted based on participant feedback. The use of the online diary tool by participants is closely monitored by study staff for completion. In a second phase, participative qualitative methods (i.e. co-creation sessions) were used to develop a smartphone application based on the diary aiming to support PrEP adherence. The efficacy of the adapted smartphone application is being tested.

Results The online diary is fully operational and being used by study participants of the PrEP demonstration project. Participants login into the secured platform on a daily base and fill in the number and timing of pills taken, whether they had sex that day and if so self-assessment of HIV risk self-assessment. The smartphone application is being finalised. Qualitative findings revealed that users prefer an application that provides scientific reliable information, is subtle and sensitive to privacy, can be used internationally, and has advanced automated features. Both online diary and smartphone application will be demonstrated.

Conclusion Web-based tools to monitor adherence to PrEP within trials are a novel and promising approach, with both advantages (eg. provides a large amount of data) and disadvantages (eg. limited validity). User-participation is an important pre-requisite to tailor such tools to target their needs.