Effectiveness of the Components of a Digital Multiple Health Behavior Intervention Among University Students (Buddy): Factorial Randomized Trial.

The skills and know-how component significantly increased fruit and vegetable consumption at both 2 and 4 months.

• At 2 months: mean difference 0.19, compatibility interval (CoI) 0.06-0.33, probability of effect (POE) 99.8%
• At 4 months: mean difference 0.14, CoI 0.01-0.28, POE 96.9%
• This was among the most consistent findings across the trial

The screening and feedback component increased fruit and vegetable consumption at both 2 and 4 months.

• At 2 months: mean difference 0.11, CoI -0.02 to 0.24, POE 94.7%
• At 4 months: mean difference 0.12, CoI -0.03 to 0.26, POE 94.4%
• This was described as one of the most consistently observed effects in the trial

The combination of screening and feedback with skills and know-how produced synergistic effects on fruit and vegetable consumption greater than either component alone.

• At 2 months: combined mean difference 0.30, CoI 0.11-0.48, POE 99.9%
• At 4 months: combined mean difference 0.26, CoI 0.05-0.46, POE 99.4%
• The combined effect exceeded the sum suggested by individual component effects

The motivation and mindfulness components, individually and in combination, increased moderate-to-vigorous physical activity (MVPA) at 2 months but not at 4 months.

• Combined effect at 2 months: mean difference 78.0 minutes/week, CoI 28.3-128.2, POE 99.9%
• The effect was not observed at 4 months, suggesting the benefit was not sustained
• Both components were examined individually and in combination

Combining screening and feedback with skills and know-how increased MVPA at 4 months.

• Mean difference 60.1 minutes/week, CoI 3.6-116.5, POE 98.2% at 4 months
• This combination effect on MVPA was observed at 4 months, unlike the motivation/mindfulness combination

Screening and feedback reduced heavy episodic drinking at 2 months, with greater effects when combined with goal-setting and mindfulness.

• Screening and feedback alone: incidence rate ratio 0.87, CoI 0.74-1.02, POE 95.2% at 2 months
• The effect was greater when screening and feedback was combined with goal-setting and mindfulness components
• This reduction was observed at 2 months

There was evidence that the motivation component was associated with harm with respect to heavy episodic drinking.

• The motivation component individually showed evidence of being harmful for heavy episodic drinking
• This was described as an unexpected finding and noted alongside the finding that motivation increased MVPA
• The paper describes this as 'some evidence' of harm

Self-authored SMS text messages were associated with harm with respect to sugary drink consumption.

• There was 'some evidence' that self-authored SMS text messages were harmful with respect to sugary drink consumption
• This finding was noted as an unexpected adverse effect of one of the intervention components
• The direction of effect was toward increased sugary drink consumption

The trial enrolled 1704 randomized students but experienced high attrition to follow-up.

• 1704 students were randomized using a double-blind factorial design with 6 two-level factors
• Available data at 2 months: 1118 participants (65.61%)
• Available data at 4 months: 874 participants (51.29%)
• Sensitivity analyses were conducted using imputed missing data to address attrition
• Participants were eligible if aged 18 or older with at least one unhealthy health behavior

The trial used a factorial design to estimate the effects of six distinct intervention components across multiple health behavior outcomes.

• Six components evaluated: screening and feedback; goal-setting and planning; motivation; skills and know-how; mindfulness; and self-authored SMS text messages
• Primary outcomes included weekly alcohol consumption, heavy episodic drinking frequency, daily fruit and vegetable consumption, weekly sugary drink consumption, weekly MVPA, and 4-week point prevalence of smoking
• Both marginal (individual) and synergistic (pairwise combination) effects were estimated
• The trial was registered as ISRCTN23310640