Recruitment interventions for trials involving adults lacking capacity to consent: methodological and ethical considerations for designing Studies Within a Trial (SWATs).

Designing a SWAT to evaluate a recruitment intervention for non-emergency trials with adults lacking capacity to consent has raised a number of methodological and ethical considerations. Explicating these challenges, and some potential ways to address them, creates a starting point for discussions about conducting these potentially more challenging SWATs. Increasing the evidence base for the conduct of trials involving adults lacking capacity to consent is intended to improve both the ability to conduct these trials and their quality, and so help build research capacity for this under-served population.