Evaluating the use of text-message reminders and personalised text-message reminders on the return of participant...

Randomised controlled trials are widely accepted as the gold standard research methodology for the evaluation of interventions. However, they often display poor participant retention. To prevent this, various participant interventions have been identified and evaluated through the use of studies within a trial. Two such interventions are participant short message service reminders (also known as text-messages) and personalised participant short message service reminders, designed to encourage a participant to return a study questionnaire. While previous studies within a trial have evaluated the effectiveness of these two retention strategies, trialists continue to spend both time and money on these strategies while the evidence remains inconclusive.

This systematic review and meta-analysis compared the use of short message service reminders with no short message service reminder and personalised short message service reminders with non-personalised short message service reminders, on participant retention. Eligible studies were identified through advanced searches of electronic databases (MEDLINE, EMBASE and Cochrane Library) and hand-searching of alternative information sources. The review primary outcome was the proportion of study questionnaires returned for the individual study within a trial primary analysis time points.

Nine eligible studies within a trial were identified, of which four compared short message service versus no short message service and five compared personalised short message service versus non-personalised short message service. For those that compared personalised short message service versus non-personalised short message service, only three were deemed appropriate for meta-analysis. The primary outcome results for short message service versus no short message service concluded that short message service led to a statistically non-significant increase in the odds of study questionnaire return by 9% (odds ratio = 1.09, 95% confidence interval = 0.92 to 1.30). Similarly, comparison of personalised short message service versus non-personalised short message service concluded that personalised short message service caused a statistically non-significant increase in odds by 22% (odds ratio = 1.22, 95% confidence interval = 0.95 to 1.59).

The effectiveness of both short message service and personalised short message service as retention tools remains inconclusive and further study within a trial evaluations are required. However, as short message services are low in cost, easy to use and generally well accepted by participants, it is suggested that trialists adopt a pragmatic approach and utilise these reminders until further research is conducted. Given both the minimal addition in cost for studies already utilising short message service reminders and some evidence of effect, personalisation should also be considered.