Stating Appointment Costs in SMS Reminders Reduces Missed Hospital Appointments: Findings from Two Randomised Controlled Trials

Background
Missed hospital appointments are a major cause of inefficiency worldwide. Healthcare providers are increasingly using Short Message Service reminders to reduce ‘Did Not Attend’ (DNA) rates. Systematic reviews show that sending such reminders is effective, but there is no evidence on whether their impact is affected by their content. Accordingly, we undertook two randomised controlled trials that tested the impact of rephrasing appointment reminders on DNA rates in the United Kingdom.
Trial Methods
Participants were outpatients with a valid mobile telephone number and an outpatient appointment between November 2013 and January 2014 (Trial One, 10,111 participants) or March and May 2014 (Trial Two, 9,848 participants). Appointments were randomly allocated to one of four reminder messages, which were issued five days in advance. Message assignment was then compared against appointment outcomes (appointment attendance, DNA, cancellation by patient).
Results
In Trial One, a message including the cost of a missed appointment to the health system produced a DNA rate of 8.4%, compared to 11.1% for the existing message (OR 0.74, 95% CI 0.61–0.89, P<0.01). Trial Two replicated this effect (DNA rate 8.2%), but also found that expressing the same concept in general terms was significantly less effective (DNA rate 9.9%, OR 1.22, 95% CI 1.00–1.48, P<0.05). Moving from the existing reminder to the more effective costs message would result in 5,800 fewer missed appointments per year in the National Health Service Trust in question, at no additional cost. The study’s main limitations are that it took place in a single location in England, and that it required accurate phone records, which were only obtained for 20% of eligible patients. We conclude that missed appointments can be reduced, for no additional cost, by introducing persuasive messages to appointment reminders. Future studies could examine the impact of varying reminder messages in other health systems.
Trial Registration
Controlled-Trials.com 49432571

## 研究背景
全球范围内，医院门诊失约是造成医疗资源低效运转的重要诱因。医疗服务机构正愈发普遍地通过短消息服务（Short Message Service，SMS）提醒来降低未赴约（Did Not Attend，缩写DNA）率。系统综述表明，此类预约提醒确实有效，但目前尚无证据表明提醒内容会对其干预效果产生影响。鉴于此，我们开展了两项随机对照试验，旨在探究英国地区门诊预约提醒的措辞调整对DNA率的影响。

## 试验方法
试验对象为持有有效手机号码、且拥有门诊预约记录的门诊患者，两项试验的招募时段分别为2013年11月至2014年1月（试验一，共10111名受试者）与2014年3月至5月（试验二，共9848名受试者）。所有预约被随机分配至4组提醒短信中的1组，所有提醒均于就诊前5日发送。随后将短信分组与预约结局（如约就诊、未赴约、患者取消预约）进行关联分析。

## 试验结果
试验一结果显示，提及失约给医疗系统造成成本的提醒短信组DNA率为8.4%，而现有标准提醒短信组的DNA率为11.1%（优势比OR=0.74，95%置信区间CI=0.61~0.89，P<0.01）。试验二重复验证了该效果（该组DNA率为8.2%），同时还发现，以笼统措辞表述相同概念的提醒短信干预效果显著更差（DNA率为9.9%，OR=1.22，95%CI=1.00~1.48，P<0.05）。若将现有标准提醒替换为更具干预效果的成本提示类提醒，可在无需额外成本的前提下，使对应英国国民保健服务信托（National Health Service Trust）机构每年减少5800例门诊失约事件。本研究存在的主要局限包括：仅在英格兰单一地区开展，且仅20%的符合条件患者能提供准确的手机号码记录。综上，通过在预约提醒中加入劝导性措辞，可在无需额外投入成本的前提下降低门诊失约率。未来可开展进一步研究，探究不同措辞的提醒短信在其他医疗系统中的干预效果。

## 试验注册
Controlled-Trials.com 49432571