Evidence Summary

What is it?

Giving potential participants a short version of the Participant Information Leaflet (PIL), generally with invitation letter.

Does it work?

Brief PILs little or no difference to recruitment.

How big is the effect?

An increase of 0.2% (95% confidence interval = -2% to 2%).

How certain are we?

GRADE Moderate certainty.


We recommend that trialists only consider brief PILs as part of a SWAT evaluation.

How can I use this straight away?

See Resource bundle below for details of how to build a SWAT evaluation of brief PILs into your trial.

Practical Impact

Imagine a trial that needs to recruit 30 participants and initial recruitment is 30% of those approached. This means you’d need to approach 100 people to recruit 30 of them (see chart).


Now imagine using a brief information leaflet. The chart below shows the impact of an absolute increase of 0.2% (95% CI = -2% to 2%). Recruitment is now 30.2%, which means our best estimate is that 99 people would now need to be approached to recruit 30 of them.

Cumulative Meta-Analysis*

*Random effects model done using Comprehensive Meta-Analysis v3 (www.meta-analysis.com).
Differences >0% favour the intervention. The GRADE assessment is moderate because of indirectness (Chen 2011 measures entry to pre-randomisation phase, not recruitment).

Resource Bundle


How to Cite

Citation: Treweek S, Bruhn H, Gardner H. Evidence pack­– Recruitment: Brief Participant Information leaflet (PIL) (Rec8), 2021, https://www.trialforge.org/recruitment-sector/brief-participant-information-leaflet/.



More Information

  1. This summary is from the Cochrane review of strategies to improve recruitment in randomised trials (https://doi.org/10.1002/14651858.MR000013.pub6).
  2. It was prepared with financial support from Evidence Synthesis Ireland.
  3. The ‘Does it work?’ statement is structured according to effect size and GRADE certainty as per GRADE Guidelines 26 (https://doi.org/10.1016/j.jclinepi.2019.10.014). The statement is for a trivial, small unimportant or no effect size and GRADE moderate certainty.
  4. The recommendation statement is the consensus view of the authors of this summary based on the GRADE certainty and features of the trials contributing to the evidence.
  5. If you have any questions contact info@trialforge.org.
Version: v1.0 - 17/12/2021

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