SIFT "Study Within A Trial" registered

Studies Within A Trial (SWATs) are smaller studies carried out within a larger clinical trial. Large studies often offer the opportunity to investigate important issues around trial design, methodology and trial processes. Examples include whether sending a letter or telephoning potential participants as a method of follow-up improves recruitment to research, or if there is an optimum time and day to send invitation letter for trials.

Response rates to follow-ups are crucial to the success of a trial and therefore it is very important to maximise response rates in participants. The SIFT study, which aimed to recruit 2800 participants and follow them up at around 2 years, provided an excellent opportunity to monitor and assess response rates. The SIFT study team designed and implemented a SWAT which compared two types of incentive to participants in follow-up - an unconditional incentive (a £15 gift voucher enclosed with the follow-up questionnaire), versus the same value voucher sent to the participant on the return of the completed questionnaire. The SIFT SWAT has been registered with the MRC SWAT Repository Store, set up by Queen's University Belfast, in order to increase transparency in trials and share knowledge on trial methodology and design with other researchers.

Results of the SWAT are currently being written up, and will be submitted for publication very soon.

This study is funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme (Reference Number 11/01/25). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.