Developing an online, searchable database to systematically map and organise current literature on retention research (ORRCA2).

ORRCA2 builds on the success of ORRCA extending the database to organise the growing volume of retention research. Less than 15% of articles were randomised evaluations of retention strategies. Mapping of the literature highlights several areas for future research such as the role of research sites, clinical staff and study design in enhancing retention. Future studies should also include cost-benefit analysis of retention strategies.