Evidence Summary
What is it?
Participants are sent an electronic prompt (SMS on the day of the questionnaire mail-out) instead of an electronic reminder (SMS 4 days after questionnaire mail-out).
Does it work?
Electronic prompts compared to electronic reminders may increase retention slightly.
How big is the effect?
An increase of 2% (95% confidence interval = -6% to 9%).
How certain are we?
GRADE Low certainty.
Recommendation
We recommend that trialists consider using electronic prompts sent out at the time of questionnaire mail-out.
How can I use this straight away?
See Resource bundle below for details of how to set up prompts and text messages to form their content
Practical Impact
Imagine initial retention is 65% of those approached. You have a trial with 100 participants that needs responses from 80 to meet its statistical power calculations. Retention of 65% means that you will be 15 responses short (see chart below).
Now imagine using electronic prompts. The chart below shows the impact of an absolute increase of 2% (95% CI = -6% to 9%). Retention is now 67%, which means our best estimate is that you would now only be 13 responses short.
Cumulative Meta-Analysis*
*Random effects model done using Comprehensive Meta-Analysis v3 (www.meta-analysis.com).
Differences >0% favour the intervention. The GRADE assessment is low because of the imprecision of a single study and a wide CI crossing RD=0.
Resource Bundle
How to Cite
Citation:Clark L, Gillies K, Torgerson D, Treweek S. Evidence pack– Retention: Electronic (SMS or email) prompts (Ret2), 2020, https://www.trialforge.org/retention-sector/electronic-sms-or-email-prompts/.
More Information
- This summary is from the Cochrane review of strategies to improve retention in randomised trials (https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.MR000032.pub3/full).
- 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 small effect size and Low GRADE certainty
- Data are published in Clark et al https://www.jclinepi.com/article/S0895-4356(15)00024-4/fulltext
- 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.
