Data and scripts underlying: Feasibility of a JITAI for healthy dietary intake: a mixed-methods study

In the project 'Measuring, analyzing and mapping environmental influences on (and changes in) spatial patterns: evidence for Just-In-Time Adaptive Interventions' (ZonMw) we collected data on the feasibility of our Just-In-Time Adaptive Intervention (JITAIs) targeting healthy dietary changes; the EetWijzer app. Four main factors were examined in this feasibility study: 1) relevance and usability, 2) receptivity 3) privacy concerns, and 4) perceived effectiveness of the Eetwijzer app. <br>Measurements and data collectionThe study was performed in the city of Wageningen, the Netherlands. Our EetWijzer app is available for Android phones in the google play store. After installing the app, participants created an account and choose a goal that they would like to work on, i.e., healthier snacking, eating less meat, or eating more vegetables and fruit. After creating an account, the app is activated and starts tracking the location of the user using GPS data collected by the smartphone of the participants when they are in the intervention geofence, i.e., the city Wageningen. Once activated, the app sends out a prompt to its user when the person enters a specific radius around a food outlet and when the person stays in this fence over a defined time threshold. It also sends prompts at moments during the day related to the chosen goal, i.e., 11.00h, 15.00h, and 20.00h for the goal healthier snacking and at 12.00h and 17.00h for the goals of eating less meat and more vegetables and fruit. The prompts that were send at the visited locations and at the pre-specified times were based on preferences of end-users as indicated during the focus groups and questionnaire study and consisted of reminders of the chosen goal, suggestions for food to be consumed, and recipes. Based on the chosen goal and on location or time, a related prompt was randomly selected and send from a list of messages in the app. Participants were included in the study when living in Wageningen, being 18 years or older and speaking Dutch. In addition, participants had to have an Android phone to be eligible for this study, as the app is not available on IOs. Participants also had to be open to improve their eating behavior to take part in this study. Study design was a 2-week feasibility study with pre and post measurements. Eligible participants were provided with an information letter about this study. After returning a signed informed consent, they were provided with information on how to install and use the EetWijzer app. When the app was successfully installed, participants were asked to fill out a baseline questionnaire. <br>The pilot lasted two weeks, in which each participant received no interventions for one week (the control week) followed by one week receiving the intervention. During the control week, the app was active in the background of the participants’ smartphones and did track location but did not send intervention prompts. During the intervention week, the app tracked the location of participants and sent intervention prompts. After receiving prompts, participants were asked to answer some questions in the app.  At the end of the two weeks, participants were asked to fill out a follow-up questionnaire. <br>The medical-ethical committee decided that we do not need medical-ethical approval. The study was approved by the Social Ethics Committee of Wageningen University and is registered at clinicaltrials.cov (NCT05773625).  <br>Eventually, 14 participants completed the study.<br>We collected data in different ways:1) with a baseline questionnaire containing age, gender, general healthiness, healthiness of the diet, chosen goal, reason for chosen goal, and healthiness of their intake related to their chosen goal.2) with a follow-up questionnaire on the healthiness of the diet and the healthiness of their intake related to their chosen goal during the intervention week; receptivity of location, time, days, emotional state; perceived effectiviness; usability; privacy concerns; preferences for the app. 3) with data collected within the app by asking questions after every prompt related to receptivity and perceived effectiveness and sometimes at the end of the day.

本项目为「测量、分析并绘制空间模式的环境影响（及变化）：即时适应性干预证据」（资助方：荷兰卫生研究与发展组织ZonMw），我们针对旨在促进健康饮食改变的即时适应性干预（Just-In-Time Adaptive Interventions，JITAIs）——即EetWijzer应用（EetWijzer app），收集了其可行性相关数据。本次可行性研究共考察四大核心维度：1）相关性与易用性；2）接受度；3）隐私顾虑；4）EetWijzer应用的感知有效性。

### 测量与数据收集
本研究在荷兰瓦赫宁恩市开展。EetWijzer应用已上架谷歌应用商店（Google Play Store），仅支持安卓（Android）设备。参与者安装应用后需注册账号，并选择一项希望达成的目标，例如更健康的零食选择、减少肉类摄入，或增加蔬果摄入。账号创建完成后，应用将启动，并通过参与者智能手机采集的GPS数据追踪用户位置，仅当用户处于干预地理围栏（geofence，即瓦赫宁恩市范围）时生效。

应用将在两类场景下向用户推送提示：其一，当用户进入食品门店周边特定半径范围，且在该地理围栏内停留时长超过预设阈值时；其二，每日与所选目标绑定的固定时段：若目标为「更健康的零食选择」，则推送时段为11:00、15:00及20:00；若目标为「减少肉类摄入」或「增加蔬果摄入」，则推送时段为12:00与17:00。

上述基于到访地点与预设时段的推送内容，均基于焦点小组与问卷调查中终端用户的偏好制定，涵盖所选目标的提醒、可食用食物建议及食谱。系统会根据参与者选择的目标、所处位置或当前时段，从应用内置的消息库中随机选取一条相关提示进行推送。

本研究的纳入标准为：居住于瓦赫宁恩市、年满18周岁、具备荷兰语使用能力，且拥有安卓设备（因该应用暂未支持iOS系统），同时愿意改善自身饮食行为。

本研究采用为期两周的可行性研究设计，包含基线与随访测量环节。符合条件的参与者将收到研究知情告知书，签署知情同意书后，将获得EetWijzer应用的安装与使用指南。应用成功安装后，参与者需填写基线问卷。

### 试验流程
本次预试验为期两周，采用「对照周+干预周」的交叉设计：第一周为对照周，应用仅在参与者智能手机后台运行并追踪位置，但不会推送任何干预提示；第二周为干预周，应用将持续追踪参与者位置并推送干预提示。参与者收到提示后，需在应用内回答若干配套问题。两周试验结束后，参与者需填写随访问卷。

### 伦理审批
本研究无需医学伦理委员会审批，已通过瓦赫宁恩大学社会伦理委员会审核，并已在ClinicalTrials.gov注册（试验编号：NCT05773625）。

### 最终招募与数据采集
最终共有14名参与者完成本研究。

本研究通过三类渠道收集数据：
1. 基线问卷：采集参与者的年龄、性别、整体健康状况、日常饮食健康程度、所选干预目标、选择该目标的动因，以及与所选目标相关的饮食摄入健康程度；
2. 随访问卷：采集参与者在干预周内的整体饮食健康程度、与所选目标相关的饮食摄入健康程度、对基于位置、时间、日期及情绪状态推送的提示的接受度、感知有效性、应用易用性、隐私顾虑，以及对应用的个性化偏好；
3. 应用内实时数据：在每次推送提示后，收集参与者关于接受度与感知有效性的反馈，部分场景下还会在每日结束时补充收集相关数据。