BackgroundMissed appointments are an avoidable cost and a resource inefficiency that impact on the health of the patient and treatment outcomes. Health-care services are increasingly utilising reminder systems to counter these negative effects.ObjectivesThis project explores the differential effect of reminder systems for different segments of the population for improving attendance, cancellation and rescheduling of appointments.DesignThree inter-related reviews of quantitative and qualitative evidence relating to theoretical explanations for appointment behaviour (review 1), the effectiveness of different approaches to reminding patients to attend health service appointments (review 2) and factors likely to influence non-attendance (review 3).Data sourcesDatabase searches were conducted on Allied and Complementary Medicine, Cumulative Index to Nursing and Allied Health Literature Plus with Full Text, The Cochrane Library, EMBASE (via NHS Evidence from 1 January 2000 to January/February 2012), Health Management Information Consortium database, Institute of Electrical and Electronics EngineersXplore, The King’s Fund Library Catalogue, Maternity and Infant Care, MEDLINE, Physiotherapy Evidence Database, PsycINFO, SPORTDiscus and Web of Science from 1 January 2000 to January/February 2012. Supplementary screening of references of included studies was conducted to identify additional potentially relevant studies. Conceptual papers were identified for review 1, randomised controlled trials (RCTs) and systematic reviews for review 2 and a range of quantitative and qualitative research designs for review 3.MethodsWe conducted three inter-related reviews of quantitative and qualitative evidence, involving a review of conceptual frameworks of reminder systems and adherence behaviours, a review of the reminder effectiveness literature and a review informed by realist principles to explain the contexts and mechanisms that explain reminder effectiveness. A preliminary conceptual framework was developed to show how reminder systems work, for whom they work and in which circumstances. Six themes emerged that potentially influence the effectiveness of the reminder or whether or not patients would attend their appointment, namely the reminder–patient interaction, reminder accessibility, health-care settings, wider social issues, cancellation and rebookings, and distal/proxy attributes. Standardised review methods were used to investigate the effectiveness of reminders to promote attendance, cancellation or rebooking across all outpatient settings. Finally, a review informed by realist principles was undertaken, using the conceptual framework to explain the context and mechanisms that influence how reminders support attendance, cancellation and rebooking.ResultsA total of 466 papers relating to 463 studies were identified for reviews 2 and 3. Findings from 31 RCTs and 11 separate systematic reviews (review 2 only) revealed that reminder systems are consistently effective at reducing non-attendance at appointments, regardless of health-care setting or patient subgroups. Simple reminders that provide details of timing and location of appointments are effective for increasing attendance at appointments. Reminders that provide additional information over and above the date, time and location of the appointment (‘reminder plus’) may be more effective than simple reminders at reducing non-attendance and may be particularly useful for first appointments and screening appointments; simple reminders may be appropriate thereafter for most patients the majority of the time. There was strong evidence that the timing of reminders, between 1 and 7 days prior to the appointment, has no effect on attendance; substantial numbers of patients do not receive their reminder; reminders promote cancellation of appointments; inadequate structural factors prevent patients from cancelling appointments; and few studies investigated factors that influence the effectiveness of reminder systems for population subgroups.LimitationsGenerally speaking, the systematic review method seeks to provide a precise answer to a tightly focused question, for which there is a high degree of homogeneity within the studies. A wide range of population types, intervention, comparison and outcomes is included within the RCTs we identified. However, use of this wider approach offers greater analytical capability in terms of understanding contextual and mechanistic factors that would not have been evident in a more narrowly focused review and increases confidence that the findings will have relevance in a wide range of service settings.ConclusionsSimple reminders or ‘reminder plus’ should be sent to all patients in the absence of any clear contraindication. Other reminder alternatives may be relevant for key groups of patients: those from a deprived background, ethnic minorities, substance abusers and those with comorbidities and/or illnesses. We are developing a practice guideline that may help managers to further tailor their reminder systems for their service and client groups. We recommend future research activities in three main areas. First, more studies should routinely consider the potential for differential effects of reminder systems between patient groups in order to identify any inequalities and remedies. Second, ‘reminder plus’ systems appear promising, but there is a need for further research to understand how they influence attendance behaviour. Third, further research is required to identify strategies to ‘optimise’ reminder systems and compare performance with current approaches.FundingThe National Institute for Health Research Health Services and Delivery Research programme.