Providing participant information over the telephone rather than face-to-face
Providing participant information over the telephone rather than face-to-face may have little or no effect on recruitment.
The absolute effect is a reduction of 7% (95% CI = -18% to 5%)1
LOW 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 providing participant information over the telephone
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 (see chart below).
Now imagine providing participant information over the telephone. The chart below shows the impact of an absolute reduction of 7% (95% CI =-18% to 5%)1. Recruitment is now 23%, which means our best estimate is that 130 people would need to be approached to recruit 30 of them.
Where has providing participant information over the telephone been tested?
Study 1: Foss 2016
Women giving birth at 1 of 3 hospitals and eligible for a vaccination trial.
Neonatal Bacille Calmette-Guérin vaccine.
Secondary care, Denmark.
85% of participants randomised to receive telephone information were recruited; 92% of participants randomised to face-to-face information were recruited
What we still don’t know about providing information over the telephone
- The GRADE assessment is low for this intervention because of imprecision and there is only a single evaluation. More evaluations in any type of trial are needed.
- Please get in touch (email firstname.lastname@example.org) if you would like to do an evaluation because we can help with text for ethics etc.