There is currently no single point of reference offering practical advice for researchers carrying out SW-CRTs. Therefore, in response to this need the broad aim of this research is to provide researchers with useful guidance for conducting SW-CRTs. It will be a two-stage project: first, this systematic review aims to identify reported problems and solutions when conducting a SW-CRT study design. The results of this review will inform the second stage, where interviews will be conducted with leading researchers involved in the SW-CRT studies included in our systematic review.