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.
Measurements and data collection
The 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.
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.
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).
Eventually, 14 participants completed the study.
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.
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