Table 3 Effect of strategies that used a change in mode of reminders delivery
Study ID | Study design | Comparator | Intervention | Difference in response rate (primary end point) | Difference in response rate (secondary end point) |
|---|---|---|---|---|---|
Hansen 2014 [33] | Prospective cohort study | A follow-up questionnaire and up to two reminders by mail | Non-responders were contacted by telephone to return postal questionnaires | Telephone contact (1 year follow-up after randomisation) raised the response by 10% from 316 (64%) to 364 (74%) | No secondary end point reported |
Varner 2017 [39] | Prospective cohort study | Participants were contacted by a conventional telephone call during the 4 months of study follow-up | Non-responders (final 3 months) were sent text message reminders of upcoming telephone follow-up for the return of postal questionnaires. | Sending text messages increased response by 22% (95% CI 5.9 to 34.7%) at 2-week follow-up | Sending text messages increased response by 17.7% (95% CI − 0.8 to 33.3%) at 4-week follow-up |