Postcard teaser campaign

Using a postcard teaser campaign aimed at recruiters makes little or no difference to recruitment of them.


The absolute increase is 0% (95% CI = -4% to 5%)1

How confident are we in the evidence?          
What is GRADE?

MODERATE CERTAINTY in the evidence (but see 'What we don't know' below)

1 Treweek S, Pitkethly M, Cook J, Fraser C, Mitchell E, Sullivan F, Jackson C, Taskila TK, Gardner H. Strategies to improve recruitment to randomised trials. Cochrane Database of Systematic Reviews 2018, Issue 2.

The practical impact of a postcard teaser campaign

Imagine a trial that needs to recruit 30 clinical sites or recruiters (e.g. family doctors) and initial recruitment is 30% of those approached. This means you'd need to approach 100 people to recruit 30 of them (see chart below).

No postcard campaign
No postcard campaign

Now imagine using a postcard teaser campaign. The chart below shows the impact of an absolute increase of 0% (95% CI = -4% to 5%)1. Recruitment is still 30%, which means our best estimate is that 100 people would still need to be approached to recruit 30.

With postcard campaign
With postcard campaign
By using a postcard teaser campaign, our best estimate is that you will still need to approach 100 sites or recruiters.

Where have postcard teaser campaigns been tested?


Postcard teaser campaign


No campaign


1 study including a total of 670 participants

Study 1: Lee 2017

Staff at primary care clinics (general practice and physiotherapy clinics) in the Sydney metropolitan area. Recruiting clinics for a trial of an intervention to reduce low back pain.

Trial intervention?
Pain education.

Study location?
Primary care, Australia.

What difference?
8.6% of those involved in the postcard teaser campaign were recruited; 8.9% of those not involved in the campaign were recruited.

Read more about this study here.

What we still don’t know about postcard teaser campaigns

  • The information we have is based on a single trial. Ideally we need to test this intervention in more trials.
  • The content of the postcard teaser remains unclear and work to establish the most appropriate content to put on the card (perhaps using behavioural change theories) would be welcome.
  • Please get in touch (email if you would like to do an evaluation because we can help with text for ethics etc.

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