Abstract: We included eight randomised controlled trials involving 6615 participants. Four of these studies were newly identified during this update. We found moderate quality evidence from seven studies (5841 participants) that mobile text message reminders improved the rate of attendance at healthcare appointments compared to no reminders (risk ratio (RR) 1.14 (95% confidence interval (CI) 1.03 to 1.26)). There was also moderate quality evidence from three studies (2509 participants) that mobile text message reminders had a similar impact to phone call reminders (RR 0.99 (95% CI 0.95 to 1.02). Low quality evidence from one study (291 participants) suggests that mobile text message reminders combined with postal reminders improved the rate of attendance at healthcare appointments compared to postal reminders alone (RR 1.10 (95% CI 1.02 to 1.19)). Overall, the attendance to appointment rates were 67.8% for the no reminders group, 78.6% for the mobile phone messaging reminders group and 80.3% for the phone call reminders group. One study reported generally that there were no adverse effects during the study period; none of the studies reported in detail on specific adverse events such as loss of privacy, data misinterpretation, or message delivery failure. Two studies reported that the costs per text message per attendance were respectively 55% and 65% lower than costs per phone call reminder. The studies included in the review did not report on health outcomes or people's perceptions of safety related to receiving reminders by text message. Low to moderate quality evidence included in this review shows that mobile phone text messaging reminders increase attendance at healthcare appointments compared to no reminders, or postal reminders. Text messaging reminders were similar to telephone reminders in terms of their effect on attendance rates, and cost less than telephone reminders. However, the included studies were heterogeneous and the quality of the evidence therein is low to moderate. Further, there is a lack of information about health effects, adverse effects and harms, user evaluation of the intervention and user perceptions of its safety. The current evidence therefore still remains insufficient to conclusively inform policy decisions. There is a need for more high-quality randomised trials of mobile phone messaging reminders, that measure not only patients’ attendance rates, but also focus on the cost-effectiveness of these interventions. Health outcomes, patients’ and healthcare providers’ evaluation and perceptions of the safety of the interventions, potential harms, and adverse effects of mobile phone messaging reminders should be assessed. Studies should report message content and timing in relation to the appointment.

Plain-language summary: The review included eight randomised controlled trials published up to August 2012, involving 6615 participants. Four of these trials were newly included in this update. Low to moderate quality evidence included in this review shows that mobile phone text messaging reminders increase attendance at healthcare appointments compared to no reminders and postal reminders, and have the same impact on attendance as phone call reminders. Two studies reported that the costs per attendance of mobile phone text message reminders are less than phone call reminders. One study reported generally that there were no adverse effects during the study period; none of the studies reported in detail on specific adverse events such as loss of privacy, data misinterpretation, or message delivery failure. The studies included in the review did not report on health outcomes or people's perceptions of safety related to receiving reminders by text message. Further randomised trials are needed to assess the effects of mobile phone messaging reminders for attendance at healthcare appointments.