JMIR Publications

ABSTRACT

Background:

University students represent a large sub-population and developing healthy behaviours during student years can have positive short- and long-term effects. Digital interventions have shown promise in this sub-population; however, few interventions have been studied that support change of multiple health behaviours simultaneously. Moreover, behavioural interventions are typically evaluated using designs that estimate the effects of interventions as a whole, making it challenging to dismantle the contribution of specific components to the overall effects.

Objective:

This study aimed to estimate the effects of six components of a digital behaviour intervention on alcohol, diet, physical activity, and smoking outcomes among university students in Sweden.

Methods:

A double-blind randomised factorial trial design with six two-level factors was used. University students in Sweden proactively recruited by student health care centres and social media at 18 geographically dispersed universities across Sweden. 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 consumption of sugary drinks; weekly moderate to vigorous physical activity; and four week point prevalence of smoking.

Results:

1704 students were randomised. Evidence for the effectiveness of individual and combined components was found across multiple health behaviours. In particular, screening and feedback, motivation, and skills and know how, produced improvements of behaviour outcomes, including alcohol consumption, smoking, fruit and vegetable consumption, and physical activity.

Conclusions:

Results highlight which components of digital interventions contribute to effectiveness and that the effectiveness of components is heterogenous across behaviours being targeted. The findings should be considered in light of the risk of bias introduced by attrition to follow-up, which in this effectiveness trial with low barriers for participation was high. The trial also used self-reported measures, although the risk of bias from this design choice may be partially mitigated as participants were blinded. Clinical Trial: The trial was prospectively registered in the ISRCTN registry on 2021-01-28 (ISRCTN 23310640).