JMIR Publications

ABSTRACT

Background:

Extant digital multiple health interventions have shown promise in various populations; however, evidence of a wider general population approach is lacking. Moreover, existent interventions often contain several components but are typically assessed as a whole, meaning we are currently unsure to what degree separate components contribute to the effects of the interventions, and how they may interact to influence health outcomes.

Objective:

The current study aimed to estimate the effects of six components of a digital behaviour intervention on alcohol, diet, physical activity, and smoking outcomes among individuals searching online for help.

Methods:

A double-blind randomised factorial trial design with six two-level factors was used. Adults of the general public in Sweden who were seeking help to change behaviours were recruited through web search and social media. Participants were included if 18 years or older and if they had at least one health behaviour classified as unhealthy. Effects of six components were estimated: screening and feedback; goal-setting and planning; motivation; skills and know how; mindfulness; and self-authored messages. Primary outcomes were weekly consumption of alcohol and frequency of heavy episodic drinking; average daily consumption of fruit and vegetables; weekly moderate to vigorous physical activity; and four week point prevalence of smoking.

Results:

5419 individuals were randomised. Overall, the screening and feedback component was the most effective for changing health behaviours, along with goal-setting, planning, and motivation to change. Several of the components interacted to further improve health outcomes, most notably the interactions of screening and feedback with motivation to change, screening and feedback with skills and knowhow, and finally motivation to change with skills and knowhow.

Conclusions:

In estimating the effects at the component level, novel insights are provided for how individual intervention components influence behaviour, along with an understanding of how they interact to further improve health outcomes. These results provide implications for the development of more effective interventions. Clinical Trial: The trial was prospectively registered in the ISRCTN registry on 2021-10-05 (ISRCTN 16420548).