Characterizing Engagement Measures and Profiles in a Mobile Health Intervention, SMS4dads.

mHealth interventions can efficiently distribute healthcare information to broad populations. However, take-up, adherence or engagement can be hard to assess. Building on previous efforts to create mHealth engagement indices, we developed an engagement metric to measure men's participation in SMS4dads, a message service for men in transition to fatherhood. Data were collected from 3261 fathers in NSW Australia in 2020-2021. An engagement metric was computed as a proportion of interactions across links and texts. Hazard ratios of dropping out were applied as external validity. To further understand men's engagement, we explored characteristics related to engagement in the program. Engagement scores did not significantly differ for rural or urban fathers. Engagement scores differed for Indigenous status, education level, first child status, antenatal enrollment, smoking status, alcohol use, and psychological distress score. The range of Engagement scores suggests that some men respond to few prompts, while others respond to almost all prompts. Understanding characteristics associated with mHealth engagement can improve precision when tailoring interventions to individual needs and vulnerable groups.