Evaluating the use of text-message reminders and personalised text-message reminders on the return of participant questionnaires in trials, a systematic review and meta-analysis

Introduction Randomised Controlled Trials (RCTs) 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 (SWATs). Two such interventions are participant Short Message Service (SMS) reminders (also known as text-messages) and personalised participant SMS reminders, designed to encourage a participant to return a study questionnaire. Whilst previous SWATs have evaluated the effectiveness of these two retention strategies, trialists continue to spend both time and money on these strategies whilst the evidence remains inconclusive. Methods This systematic review and meta-analysis compared the use of SMS reminders with no SMS reminder and personalised SMS reminders with non-personalised SMS 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 SWAT primary analysis time points. Results Nine eligible SWATs were identified, of which four compared SMS vs no SMS and five compared personalised SMS vs non-personalised SMS. For those which compared personalised SMS vs non-personalised SMS, only three were deemed appropriate for meta-analysis. The primary outcome results for SMS vs no SMS concluded that SMS led to a statistically non-significant increase in the odds of study questionnaire return by 9% (OR 1.09, 95% CI 0.92 to 1.30). Similarly, comparison of personalised SMS vs non-personalised SMS, concluded that personalised SMS caused a statistically non-significant increase in odds by 22% (OR 1.22, 95% CI 0.95 to 1.59). Conclusion The effectiveness of both SMS and personalised SMS as retention tools remains inconclusive and further SWAT evaluations are required. However, as SMS 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 SMS reminders and some evidence of effect, personalisation should also be considered