Appointment reminder systems are effective but not optimal: results of a systematic review and evidence synthesis employing realist principles

Figures & data

Figure 1 Example search strategy.

Note: Example search strategy: CINAHL Plus with Fulltext, MEDLINE, SportDiscus (via EBSCO) 2000 to January 11, 2012.

Figure 2 PRISMA flowchart for review 2 and 3.

Abbreviations: PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; SRs, systematic reviews; RCTs, randomized controlled trials; TI, titles; AB, abstracts.

Table 1 Reminder technologies covered by each review

Study	Letter	Manual telephone	Automated telephone	Mobile/SMS	Voice messaging	Email	Other
Atherton et al^Citation18						✓
Car et al^Citation34				✓
Free et al^Citation35				✓	✓
Glynn et al^Citation36	✓	✓		✓
Guy et al^Citation17				✓
Hasvold and Wootton^Citation37		✓	✓	✓
Henderson^Citation38	✓	✓	✓
Jacobson Vann and Szilagyi^Citation16	✓	✓
Krishna et al^Citation39				✓
Reda and Makhoul^Citation40	✓	✓	✓	✓		✓	Personal visit
Stubbs et al^Citation41	✓	✓	✓	✓		✓	Open access scheduling

Abbreviation: SMS, short message service.

Table 2 Reviews included in this review with an assessment of their quality

Study	Review question/aims	Overall review quality	Implications for technologies	Implications for specific populations
Atherton et al^Citation18	To assess effects of using email for coordination of health care appointments and attendance reminders, compared to other forms of coordinating appointments and reminders, on outcomes for health professionals, patients and carers, and health services, including harms.	Cochrane Empty Review with no eligible studies. A limitation of this review is the date of the search. The search was conducted in January 2010. Length of time between search date and publication of review means it is possible that relevant studies have been published in interim period.	Not applicable	Not applicable
Car et al^Citation34	To assess effects of mobile phone messaging reminders for attendance at health care appointments. Secondary objectives include assessment of patient and health care provider evaluations of intervention; costs; and possible risks and harms associated with intervention.	Cochrane Review. Included studies were of varying methodological quality; most provided insufficient information to accurately assess risk of bias. Sequence generation for randomization considered adequate (although randomization method unclear in one study) but in two studies it was not clear whether, and how, allocation was concealed. Lack of blinding in all studies can be partly explained by interactive nature of text message interventions, which does not permit blinding of participants or health care providers. Potential bias from apparent lack of blinding of outcome assessors.	Included 4 RCTs involving 3,547 participants. Three studies with moderate quality evidence showed that mobile text message reminders improved rate of attendance compared to no reminders (RR 1.10 [95% CI] 1.03 to 1.17). One low quality study reported that mobile text message reminders with postal reminders, compared to postal reminders, improved rate of attendance at health care appointments (RR 1.10 [95% CI 1.02 to 1.19]). However, two studies of moderate quality showed that mobile phone text message reminders and phone call reminders had a similar impact on health care attendance (RR 0.99 [95% CI] 0.95 to 1.03). Costs/attendance of SMS lower compared to phone reminders. No studies reported harms or adverse effects of the intervention, nor health outcomes or user perception of safety related to the intervention.	Further research should focus on older patients, given that this population has, on average, more health care appointments and uses mobile phones less frequently than the younger population.
Free et al^Citation35	To quantify effectiveness of mobile technology based interventions delivered to health care providers or to support health care services, on any health or health care service outcome.	Identified as meeting CRD criteria. No full evaluation yet available.	Pooled effect on appointment attendance using text message (SMS) reminders vs no reminder increased, with RR of 1.06 (95% CI 1.05–1.07, I^Citation2=6%). Pooled effects on number of cancelled appointments was not significantly increased RR 1.08 (95% CI 0.89–1.30). No difference in attendance using SMS reminders vs other reminders (RR 0.98, 95% CI 0.94–1.02, respectively). SMS reminders no more effective than postal or phone call reminders, and texting reminders to patients who persistently missed appointments did not significantly change number of cancelled appointments. SMS appointment reminders have modest benefits and may be appropriate for implementation.
Glynn et al^Citation36	To evaluate the effectiveness of reminders on improving the follow-up of patients with hypertension.	Cochrane Review. Included RCTs with a contemporaneous control group. The methodological quality of included studies was generally poor to moderate with 40% of included articles describing their randomization processes and only 19% describing adequate concealed allocation processes.	Included 8 RCTs investigating appointment reminder systems. All but one of the RCTs were associated with improved outcomes. The pooled results favored appointment reminder systems for follow-up of patients (odds ratio of being lost to follow-up 0.4, 95% CI 0.3 to 0.5).
Guy et al^Citation17	To assess the effectiveness of SMS reminders at increasing the uptake of appointments in health care settings.	Although gray literature was searched, it was still possible that some evaluations were not identified, particularly those with a negative outcome. Unable to assess possibility of effect according to clinical reasons for attending, as few papers presented this information. Clinical presentation could affect priority placed by patients on the need for keeping an appointment. To maximize value of future evaluations, studies should collect and report information on clinical reason for attendance as well as the visit status (new, follow-up).	Summary effect from RCTs was 1.48 (95% CI: 1.23–1.72). No significant sub-group differences by clinic type (primary care clinics, hospital outpatient clinics) or message timing (24, 48, and 72+ hours before scheduled appointment). SMS reminders substantially increase likelihood of attending clinic appointments. SMS reminders appear to be simple and efficient option for health services to improve service delivery, as well as bringing health benefits for patients who receive the reminders.	No significant sub-group differences by target age group (pediatric, adult, older). Age classification based on median age of patient receiving SMS reminders, or specification of clinic type as pediatric. RCTs demonstrated SMS reminders effective in wide age range from pediatric to older. Mobile usage data demonstrate that over 90% of population in many countries own mobile phones, but uptake is higher in younger people.^Citation86 As younger patients have higher non-attendance rates at clinical services,^Citation100 SMS reminders may be more beneficial in this group. However, older patients have considerably more health appointments each year, often at outpatient clinics where non-attendance costs UK NHS estimated £790 million per year.^Citation101
Hasvold and Wootton^Citation37	1) What is the best estimate of effect of sending reminders on non-attendance rates? 2) Are there any differences in non-attendance when using reminders sent manually (ie, from phones operated by a human) or automatically (ie, by SMS text messages or by automated voice recordings)? 3) Does time at which the reminder is sent influence the effect on non-attendance rates? 4) What are costs and benefits of using reminders?	Not classed as systematic review by DARE (CRD). PubMed only searched.	Weighted mean relative change in non-attendance was 34% of baseline non-attendance rate. Automated reminders less effective than manual phone calls (29% vs 39% of baseline value). No difference in non-attendance rate, whether reminder sent day before or week before. Cost and savings not measured formally, but almost half included cost estimates. Average cost of using either SMS, automated phone calls or phone calls was 0.41 Euros per reminder.	All studies except one^Citation102 showed positive effect from using reminders. (Patients themselves chose in advance whether they wished to receive reminder or not – potential bias in intervention group.) Overall no-show rate (outpatients in vascular laboratory) was 12% (average 7.6 missed appointments/week: gross annual revenue loss of US$89,107 based on ultrasound costs). Of 8,766 patients offered automated reminders, only 53% agreed to receive calls. No-show rate significantly greater for patients choosing automated reminders (8.9% vs 5.9%, P<0.0001).
Henderson^Citation38	To assess the effectiveness of appointment reminders as a means of increasing attendance and reducing DNA rates at new outpatient appointments.	Not classed as systematic review by DARE (CRD). Undertaken by single reviewer, with possibility of reviewer bias. Hand-searching not performed. Non-English language papers not included. Relevant material may have been missed. Methodological quality of evidence base generally poor. Several trials failed to describe randomization. In many studies blinding was poorly addressed, study participants were inadequately described and only a small number of participants were recruited.	Telephone reminders, if received, can have a positive impact on attendance and DNA rates. Postal reminders found to be effective. Although limited, literature suggests that the impact of “standard” reminders is similar to that of telephone reminders. Suggests that “Reminder plus” is more effective than “standard” reminders.	Impact of implementing initiatives on inequalities in access to services not considered by any studies included in review. Majority of included studies conducted in psychiatric settings outside the UK, raising issues of generalizability.
Jacobson Vann and Szilagyi^Citation16	To assess overall effectiveness of patient reminder or recall systems, or both, in improving immunization rates; compare effectiveness of different types of reminder or recall interventions (eg, postcard, letter, telephone), or combination of both reminder and recall.	Cochrane Review.	Reminding people over telephone, sending a letter or postcard, or speaking to them in person increased vaccinations. Providing numerous reminders was more effective than single reminders. Reminding people over telephone more effective than postcard or letter reminders. Reminders over telephone may be expensive compared with alternative approaches. Reminders worked whether from private doctor’s office, medical center, or public health department clinic. Studies all from developed countries.	Reminding people to have vaccinations increased the number of people vaccinated, whether the people were due or overdue for vaccinations. Increases were observed in both children and adults for all types of vaccines, but not among urban adolescents in one study.
Krishna et al^Citation39	To investigate role of cell phones and text messaging interventions in improving health outcomes and processes of care.	Research question supported by inclusion criteria for study design, intervention and outcomes. Authors did not report searches of unpublished data. Only studies published in English/English-language abstracts eligible for inclusion. Publication/language bias could not be ruled out. Authors did not report review process, so not known whether steps taken to reduce possible error and bias (such as performing processes in duplicate). Study quality not assessed, so unknown whether results of included studies were reliable. Many studies had small sample sizes. Narrative synthesis was appropriate given diversity of included studies. Due to possibility of bias and error in review process and unknown quality of included studies, authors’ conclusions may not be reliable.	Text messaging associated with fewer days to diagnosis (one study). Failure-to-attend rates significantly improved in two studies, but did not differ significantly between intervention/control groups in two other studies. Mobile phone reminder, disease monitoring and management, and education can improve health outcomes and care processes.	Text messaging associated with improved communication in participants with disabilities (one study).
Reda and Makhoul^Citation40	To estimate the effects of simple prompting by professional carers to encourage attendance at clinics for those with suspected serious mental illness.	Cochrane Review.	No clear difference between those prompted by telephone 1 or 2 days before appointment vs those given standard appointment management system (2 RCTs, n=457, RR missed appointment 0.84 95% CI 0.7–1.1). Text-based prompts such as a letter, a few days before the appointment day, may increase clinic attendance vs no prompt (3 RCTs, n=326, RR missed appointment 0.76 95% CI 0.43–1.32). One small study (n=61) combined telephone/text-based prompts vs no prompt, no real difference between groups (RR missed appointment 0.7 95% CI 0.4–1.2). Telephone prompts vs text-based prompts (1 RCT, n=75), the latter, as an “orientation statement” may be more effective than telephone prompt (RR missed appointment 1.9 95% CI 0.98–3.8). One study (n=120) compared standard letter prompt vs a letter orientation statement. Overall, results tended to favor orientation statement vs simple letter but not statistically significant (RR missed appointment 1.6 95% CI 0.9–2.9). For prompts regardless of type, results of greater significance suggest increased attendance (RR missed appointment 0.80 95% CI 0.65–0.98).	Indication that for serious mental illness it may be important to provide textual reminder plus orientation statement (a short paragraph, taking about 30 seconds to read, explaining the program of care, the fee system, and providing gentle encouragement).^Citation65 Contrasts with general trend in favor of telephone reminders.
Stubbs et al^Citation41	To compare telephone, mail, text/SMS, electronic mail and open-access scheduling to determine which is best at reducing outpatient non-attendance and providing net financial benefit.	Review addressed broad research question to evaluate impact of all methods for reducing outpatient non-attendance. Methods used to identify and select studies for inclusion generally clear, but publication bias cannot be ruled out. No attempts to assess study quality or minimize errors and bias in review process mentioned. Included studies extremely diverse in populations, settings, and research methods. Analysis based on simple weighted average for each approach (telephone, text, post, or open access). Influence of other relevant factors on non-attendance not explored. Authors acknowledge that only more recent studies (electronic rather than paper reminders) likely to be relevant now. Potential publication bias notwithstanding, authors conclude that most included interventions modestly improved attendance. Appears reliable, but did not investigate factors that might influence effectiveness of these interventions in different populations and settings. Different reminders not compared with each other. Conclusion that telephone reminders were better than text and post reminders may not be reliable. No formal evaluation of cost-effectiveness, so conclusion on relative cost-effectiveness of interventions also may not be reliable.	Telephone, mail, and text/SMS interventions all improved attendance modestly but at varying costs. Text messaging most cost-effective of the three, but its applicability may be limited. Few data available regarding electronic mail reminders, whereas open-access scheduling is area of active research.

Note: We acknowledge the assistance of the Centre for Reviews and Dissemination in providing quality assessments for included reviews, including the Stubbs et al⁴¹ review which was provided on demand.

Abbreviations: RCT, randomized controlled trial; RR, relative risk; CI, confidence interval; CRD, Centre for Reviews and Dissemination; SMS, short message service; DARE, Database of Abstracts of Reviews of Effects; DNA, did not attend; NHS, UK National Health Service.

Table 3 Reminder technologies assessed and outcomes reported by each RCT

Study	Study characteristics	Letter	Personalized telephone call	Automated telephone	Mobile/SMS	Voice messaging	Email	Other	Comparator	Attendance outcomes	Overall effect
Bos et al^Citation42	the Netherlands, orthodontic clinic, (N=301)	✓		✓	✓				No reminder	Standardized failure rate; respondents’ attitudes to receiving reminder; respondents’ reminder preferences	Non-attendance rate reduced by 4.5%
Can et al^Citation43	UK, orthodontic clinic, (N=231)	✓i							No reminder	Attendance rates	Non-attendance rate reduced by 4.2%
Chen et al^Citation44	People’s Republic of China, health promotion center, (N=1,859)			✓	✓				No reminder	Attendance rates; cost per attendance of intervention	Non-attendance rate reduced by 7%
Chiu^Citation45	Hong Kong, radiology outpatients, (N=311)		✓		✓				No reminder	Attendance rates	Non-attendance rate reduced by 9.4%
Cho et al^Citation46	Korea, hospital-based family practice outpatients, (N=918)	✓			✓				No reminder	Attendance rates; cost per attendance	Non-attendance rate reduced by 3.4% (SMS) and by 1.1% (telephone call)
Christensen et al^Citation47	USA, children’s dental clinic, (N=313)			✓ii					No reminder	Punctuality for appointment (15 minutes); rate of missed appointments	Non-attendance rate reduced by 21% (48 hours) and by 26% (24 hours)
Comfort et al^Citation48	USA, substance abuse clinic, (N=102)		✓						No engagement	Engagement with services	No statistically significant differences
Costa et al,^Citation49 Costa et al^Citation50	Portugal, outpatients clinics, (N=3,362)				✓				No reminder	Non-attendance rate	Non-attendance rate reduced by 3.5%
Fairhurst and Sheikh^Citation51	UK, inner-city general practice, (N=418)				✓				No reminder	Non-attendance rates	Non-attendance rate reduced by 5.3%
Goldenberg et al^Citation52	USA, teaching clinic, (N=723)		✓iii						No reminder	Attendance (show) rates	Non-attendance rate reduced by 10%
Griffin et al^Citation53	USA, colposcopy clinic, (N=1,876)		✓	✓iv					No reminder	Appointment non-attendance; patient perceptions about the call	38%, 42%, and 41% did not attend in IVR7, IVR3, and NDC arms, respectively; 33% (FS) and 38% (colonoscopy) non-attendance at baseline
Hashim et al^Citation54	USA, urban family practice, (N=930)			✓					No reminder	Outcome of call (confirmed, unable to leave message, appointment cancelled by patient/family, appointment re-scheduled by patient/family, or no active telephone number); cost of reminders	Non-attendance rate reduced by 6.9% (95% CI, 1.5%–12%)
Irigoyen et al^Citation55	USA, pediatric vaccination clinic, (N=1,273)	✓v	✓						No reminder	Appointment rates; vaccination coverage; cost of reminders	Non-attendance rate reduced by 6.7%
Kitcheman et al^Citation56	UK, inner-city outpatients, (N=764)	✓							No reminder	Attendance at first appointment; continuing attendance; hospitalization, transfer of care, discharge, presentation at accident and emergency and death by 1 year	Non-attendance rate reduced by 6.5%
Koury and Faris^Citation57	UK, ear, nose and throat clinics; (N=291)	✓			✓				No reminder	Non-attendance rate; willingness to receive SMS	Non-attendance rate reduced by 8%
Kwon et al^Citation58	USA, electrodiagnostic laboratory; (N=404)		✓						No reminder	Non-attendance without prior notification	Non-attendance reduced by 2.6% but not significantly. For appointments of particular test eg, electromyography, non-attendance rate reduced by 21.7%
Leong et al^Citation59	Malaysia, primary care clinics, (N=993)			✓	✓				No reminder	Attendance rates; costs of interventions	Non-attendance rate reduced by 10.9% (SMS); non-attendance rate reduced by 11.5% (mobile); cost of SMS reminder lower than mobile phone reminder
Liew et al^Citation60	Malaysia, primary care clinics, (N=931)			✓	✓				No reminder	Non-attendance rates	Non-attendance rate reduced by 9.3% (telephone call); non-attendance rate reduced by 7.4% (SMS)
Maxwell et al^Citation61	USA, inner-city clinics, (N=2,304)	✓		✓					No reminder	Appointment adherence rates	Non-attendance rate reduced by 3.2% (mailer). Non-attendance rate reduced by 2.1% (telephone call)
Nelson et al^Citation62	USA, pediatric dental clinics, (N=318)				✓ SMS				Mobile	Attendance rates	8.97% improvement in voice over text
Oladipo et al^Citation63	UK, colposcopy clinic, (N=189)			✓					No reminder	Attendance rate	Non-attendance rate reduced by 22%
Parikh et al^Citation64	USA, academic outpatient clinics, (N=9,835)		✓	✓					No reminder	Non-attendance rate; cancellation rate; patient satisfaction	Non-attendance rate reduced by 9.5% (personalized); non-attendance rate reduced by 5.8% (automated)
Perron et al^Citation65	Switzerland, HIV/primary care clinics, (N=2,123)	✓		✓	✓				No reminder	Rate of missed appointments, cost of intervention, and profile of patients missing their appointments	Non-attendance rate reduced by 3.6%
Prasad and Anand^Citation66	India, dental preventive care, (N=206)				✓				No reminder	Attendance rate	Non-attendance rate reduced by 43.7%
Reti^Citation67	New Zealand, hospital outpatients department, (N=109)			✓vi					No reminder	Non-attendance rates	Non-attendance rate reduced by 22%
Ritchie et al^Citation68	Australia, hospital outpatients department, (N=400)			✓					No reminder	Making the recommended appointment; attendance at scheduled appointment; and reasons for non-attendance at scheduled appointment	Non-attendance rate reduced by 16.2%
Roberts and Partridge^Citation69	UK, respiratory clinics, (N=504)			✓					Usual care	Attendance rate; cost of intervention	Non-attendance rate reduced by 15% compared with control (71%, n=258) and with patients who could not be contacted (68%, n=142) (P=0.007; P=0.004)
Rutland et al^Citation70	UK, genitourinary medicine clinic, (N=252)				✓				SMS plus health promotion message and no reminder	Re-attendance rates	Non-re-attendance rate reduced by 3.7% for text reminder only. Non-re-attendance rate reduced by 10.7% when reminder accompanied by health promotional message
Sawyer et al^Citation71	Australia, adolescent clinics (N=53)	✓		✓					No reminder	Clinic non-attendance, reason for non-attendance, and satisfaction with the booking system	Non-attendance rate reduced by 12%
Taylor et al^Citation4	Australia, physical therapy clinic, (N=679)				✓				No reminder	Rate of non-attendance without cancellation; cancellation and attendance rates; factors associated with non-attendance	Non-attendance rate reduced by 5%
Tomlinson et al^Citation72	UK, colposcopy clinic, (N=500)	✓vii							Standard information – no reminder	Attendance and default rates	Non-attendance rate reduced by 17%

i Notes: Plus reply slip;

ii telephone call at 24 hours and 48 hours prior to appointment;

iii telephone call (doctor) and telephone call (secretary);

iv interactive voice response at 3 and 7 days prior to appointment,

v postcard and postcard/telephone call;

vi telephone call from hospital and telephone call from doctor;

vii postal reminder and leaflet.

Abbreviations: N, number of participants in study; RCT, randomized controlled trial; SMS, short message service; CI, confidence interval; IVR, interactive voice response; FS, flexible sigmoidoscopy; NDC, Nurse-delivered calls.

Table 4 Judgement on quality of included trials (not already covered in included reviews)

Study	Review question/aims	Overall review quality	Implications for technologies	Implications for specific populations
Comfort et al^Citation48	To examine the effect of the provision of “tangible” engagement services during the intake period to women’s outpatient substance abuse treatment on rates of admission, retention, and service utilization. The engagement group received additional services such as transport and child care to help with the uptake and sustainability of service use.	Poor quality of reporting of the study design makes it difficult to judge quality. No reporting of blinding, allocation to groups, follow-up of all participants. The sample size was very small, which may have led to the lack of significant result.	Nil	This was a study about women receiving outpatient substance abuse programs, but did not produce any significant findings.
Costa et al,^Citation49 Costa et al^Citation50	Reduce rates of FTA by sending SMS 2 days before appointment. Sent by IT department. Personalized to extent they included: name of institution, patient name, type of appointment, date and time. When necessary, included advice to arrive earlier.	Lack of reporting on allocation to intervention groups, blinding of participants, and lack of reporting on follow-up of all participants. Sample size calculations undertaken. Seems reasonably robust study, but not well reported.	SMS improves attendance rates compared with no reminder.	Rates of non-attendance highest in younger age groups (under 15, and decreases with age); in males; people attending for the first time; people attending for tests; highest on Wednesdays; higher in the morning; varies by mobile phone network; and is higher for medical than surgical specialties, but even higher in “others” (and specialty is the most significant difference). All P<0.5.
Goldenberg et al^Citation52	Improve adherence to new patient appointments; assess effectiveness of telephone reminders on compliance; to identify other factors affecting patient adherence to appointments.	Conference abstract only, so lacks detail, RCT, sample size 393, intention to treat used. Unable to comment on blinding or process of randomization.	Direct personal contact with patient increases likelihood of attendance.	Privately insured patients more likely to attend than Medicaid patients (61% vs 46%). More deprived communities less likely to attend.
Prasad and Anand^Citation66	To evaluate the efficacy of appointment reminders, sent as SMS text messages to patients’ mobile telephones, in comparison with no reminders given to patients, at outpatient clinics at the ITS Centre for Dental Studies and Research, Muradnagar, Ghaziabad, Uttar Pradesh, India.	Randomized at departmental, rather than patient level, so differences may be due to different treatment type/patient groups. No blinding, no intent to treat analysis provided.	SMS may improve attendance rate in comparison with no reminder (although evidence weak).	When appointment reminders were being scheduled, 22 patients stated that they did not understand the English language. Reminders for these subjects were sent in the local language on the mobile phone. In addition, a picture message of the institution was sent to seven patients.
Taylor et al^Citation4	To determine whether SMS reduces rates of non-attendance in physiotherapy outpatient appointments. Secondary aims were to evaluate effect of SMS reminders on cancellation and attendance rates and explore factors associated with non-attendance.	Good quality, well powered, well conducted RCT.	Strong evidence to show that people who were not sent an SMS were 1.77 times more likely not to attend their appointment (includes adjusting for other factors).	Other statistically significant contributors to the model were health condition/diagnosis of neck and trunk musculoskeletal disorder (OR, 2.86; 95% CI, 1.53–5.32), neuromuscular disorder (OR, 3.27; 95% CI, 1.17–9.17), and age (OR, 0.98; 95% CI, 0.97–0.995).
Griffin et al^Citation53	To test whether an interactive voice response (IVR) system phone call was equally effective as nurse-delivered phone call at educating and preparing patients for flexible sigmoidoscopy (FS) and colonoscopy examinations. Outcomes were appointment non-attendance and preparation non-adherence. Non-attendance defined as cancelling appointment or not attending appointment. Appointments cancelled by clinic not considered as non-attendance. Preparation non-adherence assessed whether patients had adequately prepared to complete procedure.	Well-constructed study with sample size calculation and intent to treat, randomization not specified.	Three arm RCT; nurse phone call 7 days before procedure, IVR system call 7 days before procedure, and IVR system call 3 days before procedure. All calls included an appointment reminder, information about preparation for examination, and encouragement to prepare for and attend the examination. IVR system was effective at reminding patients of their appointments. IVR system can effectively deliver complex information, eg, preparation information; equally effectively as phone calls from clinic nurses at delivering information; patients receiving IVR messages reported more “neutral” perceptions about phone calls; patients receiving calls from nurses reported more “very positive” perceptions about phone calls.	Nil
Rutland et al^Citation70	To determine whether SMS follow-up of patients who DNA booked GUM appointments improves subsequent re-attendance rates and to assess the impact of inclusion of a health promotional message on re-attendance rates.	Conference abstract only, so lacks detail, RCT, sample size 252, unable to comment on blinding, process of randomization or intention to treat analysis.	SMS message to clinic defaulters improves re-attendance rates compared with no reminder. An SMS reminder with the addition of a health promotional message SMS follow-up of clinic defaulters improves subsequent re-attendance rates compared with a reminder alone. The addition of a health promotional message to current routine clinic reminder texts may reduce DNA rates and warrants further study (although evidence weak).	Patients with a GUM health problem did not re-attend a clinical appointment, unless a reminder was sent. Reminders and reminders with an additional health promotional message may increase the likelihood of patients with a GUM health problem re-attending a clinical appointment.
Kwon et al^Citation58	To measure the effect of telephone reminders on electrodiagnostic laboratory attendance. Electrodiagnostic laboratory bookings of patients were randomly assigned to either a telephone reminder 1 day prior to their appointment, or a routine booking (no reminder). Non-attendance was the primary outcome measure, defined as non-attendance without prior notification.	Conference abstract only, so lacks detail, RCT, sample size 404, unable to comment on blinding, process of randomization or intention to treat analysis.	Telephone reminders reduced non-attendance at all appointments by 2.6% but not significantly. For appointments of particular test eg, electromyography, non-attendance rate reduced by 21.7%. This may indicate that specific types of technical appointments may be more effectively targeted (although evidence weak).	Patients who may be concerned that they have a genuine health problem may be more effectively targeted by telephone reminders.
Chiu^Citation45	To investigate the effectiveness of telephone reminders on attendance at CT scan appointments. The primary outcome measure was non-attendance at CT scan appointments.	Good quality, well powered, well conducted RCT.	Telephone reminders were effective at reducing non-attendance rate for radiological appointments. Patients who were successfully contacted were significantly more likely to attend than those patients who were not successfully contacted.	Nil
Koury and Faris^Citation57	To investigate the effectiveness of using an SMS reminder compared with usual procedures in NHS ENT outpatient departments. Primary outcome was attendance rates in each of the groups.	Lack of reporting on randomization procedures, allocation to intervention groups, blinding of participants, and lack of reporting on follow-up of all participants. No information about sample size calculations undertaken. Seems reasonably robust study, but likely that editorial constraints may have led to poor reporting.	In comparison with no reminder, SMS reminders were effective at reducing non-attendance rates at ENT appointments.	Nil

Abbreviations: FTA, failed to attend; SMS, short message service; IT, information technology; RCT, randomized controlled trial; OR, odds ratio; CI, confidence interval; IVR, interactive voice response; FS, flexible sigmoidoscopy; DNA, did not attend; GUM, genitourinary medicine; CT, computerized tomography; NHS, UK National Health Service; ENT, ear, nose and throat.

Figure 3 Summary of strategies to optimize reminder systems.

Abbreviation: SMS, short message service.

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