Opt-out rather than opt-in consent
Using opt-out consent rather than opt-in consent may improve recruitment.
19%
The absolute increase is 19% (95% CI = 3% to 35%)1
LOW CERTAINTY in the evidence (but see 'What we don't know' below)
The practical impact of opt-out consent
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 below).
Now imagine using a opt-out consent. The chart below shows the impact of an absolute increase of 19% (95% CI = 3% to 35%)1. Recruitment is now 49%, which means our best estimate is that 61 people would need to be approached to recruit 30 of them.
Where has opt-out consent been tested?
Intervention:
Comparison:
Scale:
Study 1: Trevena 2006
Participants?
Participants were aged 50 to 74 and eligible for a colorectal cancer screening trial.
Trial intervention?
Decision aid.
Study location?
Primary care, Australia.
What difference?
66.6% of those allocated to opt-out consent were recruited; 46.7% of those allocated to opt-in consent were recruited.
What we still don’t know about op-out consent
- The information we have is based on a single trial. The distribution of participants between intervention and comparison groups is uneven: 60 versus 92, respectively. This was due to a change in legislation in Australia, which meant that the trialists could no longer continue with the opt-out procedure and had to change to opt-in to keep their ethical approval. Ideally we need to test this intervention in more trials.
- Please get in touch (email info@trialforge.org) if you would like to do an evaluation because we can help with text for ethics etc.
