Participants
RECRUITMENT
The recruitment of employees from the private and public sector took place in six different European businesses in Germany, England, and Northern Ireland. Potential participants were informed about trial participation through intraorganization communication channels such as emails, newsletters, intranet posts, or word of mouth, which varied by trial site. In total, 678 participants were recruited, of whom 621 completed the questionnaires at baseline, 483 completed the midintervention questionnaires, 396 completed the postintervention questionnaires, and 363 completed the 2-week follow-up questionnaires. Of the participants randomized into the app group (intervention group), 137 did not use the app at all and were therefore excluded from the analyses. Nine participants in the waitlist group downloaded the app before the end of the trial and were also excluded. Thus, the final sample consisted of 532 participants, with 210 in the intervention group and 322 in the waitlist control group (Participation flow diagram.