Evidence Summary
What is it?
Offering potential participants a financial incentive (£5 to £100) to take part in a trial.
Does it work?
Financial incentives probably increase recruitment slightly.
How big is the effect?
An increase of 4% (95% confidence interval = -1% to 8%).
How certain are we?
GRADE Moderate certainty.
Recommendation
We suggest that trialists consider using financial incentives, ideally as part of a SWAT evaluation.
How can I use this straight away?
See Resource bundle below for details of how to use financial incentives or build a SWAT evaluation of them 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 £5 to £100 financial incentive at recruitment. The chart below shows the impact of an absolute increase of 4% (95% CI = -1% to 8%). Recruitment is now 34%, which means our best estimate is that 88 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. GRADE assessment is moderate because of inconsistency.
Resource Bundle
How to Cite
Citation: Treweek S, Bruhn H, Gardner H. Evidence pack– Recruitment: Financial incentives (Rec3), 2021, https://www.trialforge.org/recruitment-sector/financial-incentives/.
More Information
- This summary is from the Cochrane review of strategies to improve recruitment in randomised trials (https://doi.org/10.1002/14651858.MR000013.pub6).
- It was prepared with financial support from Evidence Synthesis Ireland.
- 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 small important effect size and GRADE moderate certainty.
- 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.
- If you have any questions contact info@trialforge.org.
