A new opportunity for enhancing trial efficiency: Can we investigate intervention implementation processes within trials using SWAT (study within a trial) methodology?

Background A study within a trial (SWAT) is a self-contained research study embedded within one or more host trials to evaluate or explore alternative ways of delivering or organising a particular trial process. There is limited evidence of SWATs evaluating trial processes other than recruitment and retention. Purpose Embedding a SWAT into a host trial provides a potential method of evaluating an aspect of intervention implementation, such as engagement or compliance with the intervention. Research Design This paper presents two case studies of SWATs which aim to test the use of video animations to improve intervention implementation, with particular focus on enhancing understanding, engagement and compliance. These are important aspects of intervention implementation as they are directly linked to intervention effectiveness and therefore, important to study. Results In this paper, we present the potential benefits of conducting SWATs of intervention implementation processes as well as discussing the methodological considerations for embedding a SWAT of this nature within a host trial. Benefits include the opportunity to test minor refinements to intervention implementation within trials through robust randomised SWATs, and the possibility of increasing trial efficiency by maximising the quality or quantity of intervention implementation. Methodological considerations surrounding the design and conduct of the SWAT as well as statistical and health economics considerations are discussed in this paper. Conclusions This paper presents a novel application of SWAT methodology in investigating intervention implementation processes within trial conduct.