Introduction: Chronic health conditions and common mental disorders can be prevented by improving six health risk behaviours among adolescents (the 'Big 6'): physical inactivity, poor nutrition and sleep, sedentary screen use, and using alcohol and cigarettes/vapes. The 'Big 6' are particularly prevalent among adolescents experiencing socio-economic disadvantage. While parent-focussed interventions can be effective for improving health risk behaviours among adolescents, few parent-focussed interventions target multiple health risk behaviours concurrently, and even fewer are specific to families experiencing socio-economic disadvantage.
Purpose: This presentation reports findings from the 'Optimisation Phase' of a Multiphase Optimisation Strategy (MOST) trial, which tested five components of a parent-focused digital intervention to determine which elements, individually and in combination, most effectively enhanced parents' encouragement of adolescents' healthy behaviours across the 'Big 6'.
Method: A 2x4 factorial design is being implemented among parents (N=303) experiencing socio-economic disadvantage in Australia. Parents were randomised to one of 16 intervention combinations. All receive six interactive online modules (one per week, for each of the 'Big 6'). Parents are randomised to receive 1 of 16 combinations of additional components: text messages, telehealth coaching, personalised feedback, and stress management training. Parents complete surveys at baseline and 3-months post-baseline. The primary outcome is change in parental encouragement of adolescent health behaviours at 3-months.
Results: Recruitment is complete (N=303 parents) and 3-month follow-up survey completion rate is currently 75% (N=120 of 161 due). We anticipate follow-up data collection will be complete by January 2026, and analyses complete by February 2026. Results will guide assembly of an 'optimised intervention package' that achieves greatest improvement in parental encouragement of adolescent health behaviours, with the least possible resource burden.
Conclusions: This is the first study to use the MOST framework to co-design a digital parenting intervention targeting multiple health risk behaviours for chronic disease and comorbid mental disorders.