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Trial Forge additional guidance


Published: 27 February 2023

Version: 1.0

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One way to fill gaps in study process evidence (e.g. on recruitment, retention, monitoring or data collection) is to run methodological sub- studies, or SWATs/SWARs. After a successful pilot conducted in the Health Technology Assessment (HTA) Programme, we are now encouraging applicants to embed methodological sub-studies (up to a maximum funding of £30,000) into applications to the following programmes: 

Building a SWAT/SWAR into a study doesn’t mean that you have to develop a SWAT/SWAR intervention from scratch because replication studies (i.e. testing an existing intervention in a different study) are essential to build robust evidence to support decision-making. If you’d like ideas about SWAT interventions, have a look at the SWAT/SWAR repository of SWAT/SWAR protocols. The Cochrane recruitment and Cochrane retention reviews also suggest SWATs that are priorities for replication.

In addition to these resources, the Trial Forge SWAT Centre at the University of York has set up a Trial Forge SWAT Network to support researchers in the UK and elsewhere in doing SWATs/SWARs. For further information, please email

How much to write on SWATs/SWARs in Stage 1 and 2 proposals

A recurring question raised at SWAT Network meetings has been "How much do we have to write about the SWAT in NIHR Stage 1 and Stage 2 proposals?" Please refer to the following information as guidance. 

Stage 1

Words are precious at Stage 1 and commitees recognise this. Although extreme, simply flagging that a SWAT/SWAR is planned – "We plan to include a SWAT/SWAR" – would suffice. There may be committee murmurings about brevity, but the chances of moving on to Stage 2 will not be affected. Despite this, you can expect to be asked for more details if you do progress.

You could, however, do better without spending too many words. For guidance, we have provided two examples, both of which include more than enough SWAT information for a Stage 1 submission, despite both being under 60 words.

Example 1

This example is from a real and successful Stage 1 submission: We plan to include a SWAT to evaluate different approaches of presenting study design to participants during the recruitment process.

Example 2

This example is not from a real submission, but is an example of what you could write: We plan to evaluate a short version of the Patient Information Leaflet (PIL) in a SWAT. We have concerns that a long PIL may be challenging for our participant group and the Trial Forge ID REC8 evidence summary for brief PILs recommends their use only in the context of a SWAT evaluation.

Stage 2

Stage 2 needs more than one sentence. There has to be some detail on the rationale for the SWAT/SWAR, the process targeted and the type of SWAT/SWAR intervention. The intention is to let the committee know in broad terms what is planned, while still recognising that the application will stand or fall on the trial, not the SWAT/SWAR.

Using the previous two Stage 1 examples (the first one from a real submission, the second illustrative), we have provided two examples of what the corresponding Stage 2 text could be. Both examples will give the committees a clear idea of what is proposed, and both are well under 250 words.

Example 1

YTU [York Clinical Trials Unit] has significant experience in undertaking methodological SWATs. The unit has completed and published more than 20 SWATs and has previously undertaken work with the Medical Research Council (PROMETHEUS study) to support collaborative trials units to undertake further SWATs. In this trial we propose to undertake at least two SWATs on recruitment and retention.

For recruitment we will evaluate the effects of presentation of the study design to participants on recruitment rate. Participants will be randomised to receive an infographic (visual document explaining the study) plus the standard patient information sheet (PIS), or just the PIS.

The retention SWAT will use a 2:2 factorial design to simultaneously evaluate the effect of two retention strategies: a participant newsletter and a thank you card sent in advance of follow up questionnaires. Participants will be randomised to receive:

  1. newsletter and thank you card
  2. newsletter only
  3. thank you card only
  4. neither the newsletter, nor the thank you card

As is usual with embedded trials, the sample size is constrained by the number of patients approached about the study (recruitment) or actively participating within each host trial (retention), hence a formal power calculation to determine sample size has not been conducted.

The strategies proposed here are either already registered or will be registered prior to implementation on the MRC SWAT repository.

Example 2

Evidence suggests that our participant group is likely to have low literacy. Long written PILs are likely to be off-putting and far less useful than the conversation between recruiter and potential recruit. Short PILs have been tested before (Trial Forge REC8) and demonstrated little effect on recruitment. We think the previous evaluations paid insufficient attention to the content of the short PIL, especially who decided what was on it. We will work with representative public contributors to decide what should be on the short PIL and we will work with our sponsor and ethics committee to ensure our information provision is in line with appropriate governance. Some of our information provision will be explicitly verbal rather than written, in line with HRA guidance on the process of seeking consent.

In line with Trial Forge REC8 recommendations, the evidence base for short PILs is such that they should only be used in the context of a SWAT evaluation, which is what we intend to do. The measured outcomes for the SWAT will be: recruitment, retention, and cost.


NIHR committees recognise that words are limited and that the main trial needs most of those words. At Stage 1 applicants simply need to flag that a SWAT/SWAR is planned. At Stage 2 a few more details are needed but there is no need to go overboard.