SMS text pre-notification and delivery of reminder e-mails to increase response rates to postal questionnaires in the SUSPEND trial: a factorial design, randomised controlled trial

Abstract

SMS text pre-notification of questionnaire delivery and email delivery of questionnaire reminders did not improve response rates. There was some evidence to suggest that SMS text pre-notification may be effective in women, and further studies to investigate this may be warranted. E-mail reminders for participants to return their postal questionnaire could be advantageous given that response rates were similar following either type of reminder and the low cost of delivering an e-mail compared with a postal reminder. This is a substudy of the SUSPEND trial (ISCTRN69423238) (18 Nov. 2010).