Summary of findings 12. Non‐monetary incentives: addition of pen vs usual follow‐up.
Pen compared with no pen for trial retention | |||||
Patient or population: trial participants being followed up for data collection Settings: any setting Intervention: pen Comparison: no pen | |||||
Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of Participants (studies) | Certainty of the evidence (GRADE) | |
Assumed risk | Corresponding risk | ||||
Pen | No pen | ||||
Retention [follow‐up] |
Lowa | RR 1.02 (1.00 to 1.05) | 13013 (5) | ⊕⊕⊝⊝ low | |
25 per 100 | 26 per 100 (25 to 26) | ||||
Mediuma | |||||
50 per 100 | 51 per 100 50 to 53) | ||||
Higha | |||||
80 per 100 | 82 per 100 (80 to 84) | ||||
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RR: risk ratio. | |||||
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | |||||
a We selected low, medium and high illustrative retention levels of 25%, 50% and 80% based on prior experience with trial retention and evidence from the literature. For example, it has been previously stated that it is common for up to 20% trial participants to drop out before the trial finishes (Walsh 2015), as such we set the upper limit of good retention as 80%. The other extreme of 25% was informed by evidence that some trials (largely internet based) can have retention as low as 10% to 25% (Murray 2009). The mid point of 50% was a judgement made by the review team and was deemed appropriate given the evidence for the other parameters. |