These three associated reviews have found strong, consistent evidence to support the use of all reminder systems for all patients in any outpatient setting for increasing attendance, cancellation or rescheduling. There is additional evidence that ‘reminder plus’, which provides additional information over and above date, time and location of the appointment, may be more effective than simple reminders at reducing non-attendance, particularly at first appointments. However, there is a need for high-quality studies investigating the differential influence of providing additional information as part of the reminder system in different contexts (first compared with follow-up appointment, the use of loss- compared with gain-framed messages and orientation information for facilitating attendance behaviours).

There was strong evidence that:

• the timing of reminders, between 1 and 7 days prior to the scheduled appointment, has no effect on attendance
• a substantial number of reminders may not be received by patients
• reminders promote cancellation of appointments
• patients find difficulty with cancelling appointments because of structural factors affecting reminder systems (e.g. busy telephone line, nobody answers the telephone).

This leads to the conclusion that, unless patients indicate otherwise, all patients should receive a reminder or ‘reminder plus’ that actively encourages patients who are unable to attend to cancel their appointment and to reschedule if further appointments are required. The reminder should be sent around 3 days in advance of the appointment as timing of a reminder, between 1 and 7 days prior to the scheduled appointment, has no effect on patient attendance behaviour. This will allow sufficient time for patient cancellation and health service reallocation of the appointment to another patient or allow the clinician to undertake care-related administrative tasks. To optimise attendance, cancellation and rescheduling there needs to be robust procedures to ensure that patient contact details are up to date and that there are easy to use, probably multiple, systems for cancelling appointments that suit the needs of the patients, e.g. automated SMS cancellation, answerphone, e-mail, etc. Robust 24-hours-per-day rescheduling procedures should allow easy rescheduling of appointments for patients. Finally, an effective reminder system will increase the workload on clinical staff and alternative time will need to be scheduled for staff to undertake health-care-related administration. Further research is required to investigate the differential effectiveness and cost-effectiveness of an ‘optimised’ reminder system over and above usual reminder systems.

There were few studies investigating the differential effectiveness of alternative types of reminders for different segments of the population and this we believe is a key area for further research. Nevertheless, we have used the findings of our review to suggest possible reminder alternatives for key groups of patients who appear to be at higher risk of not attending appointments, namely deprived, ethnic, substance abusers, and those with comorbidities and illness. Simple reminders and automated reminders to attend may be ignored or overlooked and may put these patient groups at a disadvantage compared with general outpatient populations. Reminders with direct personal contact might be appropriate in these groups. To facilitate attendance in the most at risk, vulnerable groups we have suggested that reminder systems of increasing intensity and interactivity could be introduced to ensure that disparities in health-care opportunities are not compounded. We have introduced the concept of a sequential reminder intervention in order to reach the most number of patients and maximise attendance, although their effectiveness in this context needs to be established. The re-engagement of these patient groups with treatment after they have missed their appointment may be important if they have particular health problems that need ongoing treatment. Intensive approaches, such as ‘stepped reminders’ and patient navigators have been effective at increasing attendance at screening and immunisation programmes in disadvantaged and vulnerable populations, although their effectiveness in this context needs to be investigated.

Reminder systems are a complex intervention, because of the potential number of interacting components within the interventions, the requirement for tailoring of the intervention to the health service and the number of difficulties and behavioural changes from those receiving and delivering the reminder. Therefore, in addition to following the general recommendations provided above, health service managers will need to tailor their reminder systems to meet the needs of the service and the patient population that it serves. This review provides a range of findings that will inform health service managers’ decision-making processes. To this end, we are producing a practice guide to help health service managers consider specific issues that may be relevant to the design of reminder systems for their health service.