Effect of Opt-In vs Opt-Out Framing on Enrollment in a COVID-19 Surveillance Testing Program: The COVID SAFE Randomized Clinical Trial

Do recruitment SWAT interventions have an impact on participant retention in randomised controlled trials? A systematic review

BACKGROUND

Evidence-based methods for randomised controlled trial recruitment and retention are extremely valuable. Despite increased testing of these through studies within a trial, there remains limited high-certainty evidence for effective strategies. In addition, there has been little consideration as to whether recruitment interventions also have an impact on participant retention.

METHODS

A systematic review was conducted. Studies were eligible if they were randomised controlled trials using a recruitment intervention and which also assessed the impact of this on retention at any time point. Searches were conducted through MEDLINE, EMBASE, Cochrane Library, and the Northern Ireland Hub for Trials Methodology Research SWAT Repository. Two independent reviewers screened the search results and extracted data for eligible studies using a piloted extraction form.

RESULTS

A total of 7815 records were identified, resulting in 10 studies being included in the review. Most studies (n = 6, 60%) focussed on the information given to participants (n = 6, 60%), with two (20%) focussing on incentives, and two focussing on trial design and recruiter interventions. Due to intervention heterogeneity, none of the interventions could be meta-analysed. Only one study found any statistically significant effect of letters including a photograph (odds ratio: 5.40, 95% CI 1.12-26.15, p = 0.04).

CONCLUSION

Assessment of the impacts of recruitment strategies, evaluated in a SWAT, on retention of participants in the host trial remains limited. Assessment of the impact of recruitment interventions on retention is recommended to minimise future research costs and waste.

COVID-19 test-to-stay program for K-12 schools: Opt-in versus opt-out consent model

The Centers for Disease Control and Prevention promoted the Test-to-Stay (TTS) program to facilitate in-person instruction in K-12 schools during COVID-19. This program delineates guidelines for schools to regularly test students and staff to minimize risks of infection transmission. TTS enrollment can be implemented via two different consent models: opt-in, in which students do not test regularly by default, and the opposite, opt-out model. We study the impacts of the two enrollment approaches on testing and positivity rates with data from 259 schools in Illinois. Our results indicate that after controlling for other covariates, schools following the opt-out model are associated with 84% higher testing rate and 30% lower positivity rate. If all schools adopted the opt-out model, 20% of the total lost school days could have been saved. The lower positivity rate among the opt-out group is largely explained by the higher testing rate in these schools, a manifestation of status quo bias.

Is opt-out enrolment acceptable for low-risk digital health services?

Introduction Digital health programmes not only complement existing services, but have the potential to reach populations that existing services are not reaching. Many of these services require people to opt-in to receive them, which presents significant barriers to access. An alternative is to make low-risk digital services opt-out, ensuring appropriate members of the target audience are signed up for a service unless they select to not receive it. Aim This study aimed to investigate how changing enrolment in a low-risk digital health programme from opt-in to opt-out would impact on enrolment and dropout rates. Methods This study involved the retrospective analysis of registration data from txtpēpi, a maternal and child health text-message programme. System-recorded data from enrolments during a 12-month period were obtained. In the first 6 months, users had to opt-in to the service (Period 1), but in the following 6 months, an opt-out process was implemented (Period 2). Results There was a 77% increase in enrolments in Period 2 (n  = 113) compared to Period 1 (n  = 64) and no significant change in the proportion of enrolments of Māori between time periods (P  = 0.508). There was no significant difference in withdrawal rates between time periods at either 2 weeks (5% vs 6%, P  = 0.676) or 1 month (9% vs 9%, P  = 0.907). Discussion This study has shown switching from an opt-in to an opt-out option resulted in an increase in enrolments in an mHealth programme, but had no impact on withdrawals. This indicates that employing opt-out enrolment for low-risk evidence-based interventions is acceptable and a potential way to make these services more accessible.