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Effectiveness of the Components of a Digital Multiple Health Behavior Intervention Among University Students (Buddy): Factorial Randomized Trial
Linköping University, Department of Health, Medicine and Caring Sciences, Division of Society and Health. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Regionledningskontoret, Enheten för folkhälsa.ORCID iD: 0000-0003-2194-6789
Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center of Paediatrics and Gynaecology and Obstetrics, H.K.H. Kronprinsessan Victorias barn- och ungdomssjukhus. Linköping University, Department of Health, Medicine and Caring Sciences.ORCID iD: 0000-0001-7883-3895
Linköping University, Department of Health, Medicine and Caring Sciences, Division of Society and Health. Linköping University, Faculty of Medicine and Health Sciences. Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden.ORCID iD: 0000-0003-3571-1497
Linköping University, Department of Health, Medicine and Caring Sciences, Division of Society and Health. Linköping University, Faculty of Medicine and Health Sciences.ORCID iD: 0000-0003-2482-7048
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2026 (English)In: Journal of Medical Internet Research, E-ISSN 1438-8871, Vol. 28, article id e88884Article in journal (Refereed) Published
Abstract [en]

Background:Digital interventions have shown promise in supporting healthy behaviors among university students; however, few interventions support simultaneous change across multiple health behaviors. Moreover, behavioral interventions are typically evaluated as a whole, making it challenging to disentangle the contribution of individual components to the overall effects.

Objective:This study estimated the effects of the components of a digital behavior intervention on alcohol, diet, physical activity, and smoking outcomes among university students in Sweden.

Methods:A double-blind randomized factorial trial with 6 two-level factors was conducted. University students in Sweden were proactively recruited through student health care centers and social media. Participants were eligible if they were aged 18 years or older and had at least one health behavior classified as unhealthy. The effects of 6 components were estimated: screening and feedback; goal-setting and planning; motivation; skills and know-how; mindfulness; and self-authored SMS text messages. Primary outcomes were weekly alcohol consumption and frequency of heavy episodic drinking, average daily fruit and vegetable consumption, weekly sugary drink consumption, weekly moderate-to-vigorous physical activity (MVPA), and 4-week point prevalence of smoking.

Results:A total of 1704 students were randomized. The effectiveness of individual and pairwise components was estimated using available data from 1118 (65.61%) participants at 2 months and 874 (51.29%) at 4 months, with sensitivity analyses conducted using imputed missing data. Most consistently, the evidence indicated that screening and feedback affected fruit and vegetable consumption (2-month mean difference 0.11, compatibility interval [CoI] –0.02 to 0.24; probability of effect [POE] 94.7% and 4-month mean difference 0.12, CoI –0.03 to 0.26; POE 94.4%), as did skills and know-how (2-month mean difference 0.19, CoI 0.06-0.33; POE 99.8% and 4-month mean difference 0.14, CoI 0.01-0.28; POE 96.9%). The combination of these 2 components was even more effective (2-month mean difference 0.30, CoI 0.11-0.48; POE 99.9% and 4-month mean difference 0.26, CoI 0.05-0.46; POE 99.4%). The motivation and mindfulness components, both individually and in combination, increased MVPA at 2 months (combined mean difference 78.0, CoI 28.3-128.2; POE 99.9%); however, this effect was not observed at 4 months. Combining screening and feedback with skills and know-how increased MVPA at 4 months (mean difference 60.1, CoI 3.6-116.5; POE 98.2%). Heavy episodic drinking was reduced at 2 months by screening and feedback (incidence rate ratio 0.87, CoI 0.74-1.02; POE 95.2%), and the effect was greater when combined with goal-setting and mindfulness. There was some evidence that the motivation component was harmful with respect to heavy episodic drinking and that self-authored SMS text messages were harmful with respect to sugary drink consumption.

Conclusions:We dismantled a complex digital multiple behavior intervention and examined it using a factorial design to provide novel insights into the effectiveness of the intervention’s different components. Both marginal and synergistic effects were observed across multiple behaviors, providing evidence regarding which components are most promising in complex interventions. These findings should be considered in light of the risk of bias introduced by attrition to follow-up, which was high in this effectiveness trial with low barriers to participation.

Trial Registration:International Standard Randomised Controlled Trial Number (ISRCTN) ISRCTN23310640; https://www.isrctn.com/ISRCTN23310640

Place, publisher, year, edition, pages
JMIR Publications, 2026. Vol. 28, article id e88884
Keywords [en]
behavior change; digital interventions; multiple lifestyle; public health; mHealth intervention
National Category
Public Health, Global Health and Social Medicine
Identifiers
URN: urn:nbn:se:liu:diva-221874DOI: 10.2196/88884ISI: 001712424600007PubMedID: 41802225Scopus ID: 2-s2.0-105032562472OAI: oai:DiVA.org:liu-221874DiVA, id: diva2:2045798
Note

Funding: Swedish Research Council for Health, Working Life and Welfare (grant 2018-01410; principalinvestigator: ML), the Swedish Cancer Society (Cancerfonden; grants 20 0883 Pj and 23 2888 Pj; principal investigator: MB).

Available from: 2026-03-13 Created: 2026-03-13 Last updated: 2026-03-26
In thesis
1. Buddy: A digital intervention promoting multiple health behavior change among university and college students in Sweden
Open this publication in new window or tab >>Buddy: A digital intervention promoting multiple health behavior change among university and college students in Sweden
2025 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background

University and college students in Sweden represent a significant and diverse subgroup of the working-age population. The transition to student life brings changes to individuals’ lifestyle, including the development of unhealthy behaviors such as risky alcohol consumption, unhealthy diets, physical inactivity, and smoking. These unhealthy behaviors increase the risk of non-communicable diseases and impact both short- and long-term physical and mental health. Additionally, unhealthy behaviors often co-occur, further increasing the risk of negative consequences. Therefore, supporting healthy behaviors during student years is important, to mitigate short- and long-term health risks. Digital interventions to support behavior change have shown promise, however, there is a lack of evidence regarding the effectiveness of the individual components of which interventions consist, and for interventions which target multiple health behaviors simultaneously.

Aim

This thesis aimed to design and evaluate a digital multiple health behavior intervention, called Buddy, targeting Swedish university and college students’ alcohol consumption, diet, physical activity, and smoking behaviors. The included studies investigated students’ perspectives on health and well-being, the effectiveness of Buddy’s components, students’ interactions with Buddy, and their experiences of the behavior change process.

Studies

In Study I, a qualitative design with digital interviews was used to investigate students’ experiences of health, health-related behaviors, and behavior change. Verbatim transcripts were analyzed in alignment with the phenomenological hermeneutic tradition. The results show that students make choices which are influenced by student culture and academic demands. Students also face new health-related challenges, for example study-related stress and managing a limited budget. These influences sometimes makes it challenging to prioritize healthy routines, and students strive to enhance academic performance while enjoying student life. As students transition through their academic years, they develop strategies to maintain their health and quality of life, gradually becoming more independent and self-reliant in their health-related choices.

In Study II, a factorial randomized trial was used to estimate the effectiveness of the components of the Buddy intervention on health behaviors. The results showed that access to Buddy’s components led to improvements in alcohol consumption, fruit and vegetable consumption, physical activity, smoking cessation, and stress. All components, apart from the goal-setting and challenges component, individually showed benefit on at least one health behavior. Larger effects were observed when components were combined. However, access to some components also produced increased consumption of sugary drinks, candy and snacks, and increased BMI.

In Study III, a multiple methods design was employed to explore the fidelity of the Buddy intervention by gaining insights into trial participants’ interactions with the goal-setting and challenges component. Participants used Buddy to set goals for both single and multiple health behaviors, customizing Buddy to meet their unique behavior change needs. Individual characteristics were associated with the likelihood of setting goals and interacting with challenges, as well as the interaction with specific behavior goals and challenges. The self-authored content showed that the component was mainly used to improve physical activity and dietary behaviors, while also addressing study-related aspects, mental health, screen time, and sleep routines.

In Study IV, a qualitative design was employed to understand why students’ chose to participate in Buddy and their subsequent experiences of the behavior change process. Trial participants who had completed the final follow-up were interviewed by phone. Verbatim transcripts were analyzed in alignment with the phenomenological hermeneutic tradition, focusing on respondents’ narratives of the behavior change process. The results illustrate that the study population could be described by seven different personas who had varying intentions and levels of engagement with Buddy and the behavior change process. The findings suggested that Buddy was most effective for students who fit the persona of having a goal-focused mindset, clear reasons for change, awareness of their needs, the ability to interpret information and reflection into action, and had the energy needed to implement changes.

Conclusions

Students’ experiences of health and behavior change can be described as a transition, a balancing act, similar to walking on a slack line, where students seek a healthy balance while navigating their academic years. When offered digital support for behavior change, students customize the support to meet their needs, even beyond the targeted behaviors. The content of the digital support impacts effectiveness, and the effectiveness of individual components and their combinations are heterogenous across targeted behaviors. Successfully supporting students towards healthier behaviors using digital interventions depends on interactions between the digital delivery mode and intervention content, with students’ individual expectations, needs, skills, and life situations.

Abstract [sv]

Bakgrund

Universitets- och högskolestudenter utgör en betydande och mångfacetterad andel av den arbetsföra befolkningen i Sverige. Övergången till studentlivet innebär förändringar i individers livsstil, inklusive utvecklingen av ohälsosamma levnadsvanor såsom riskfylld alkoholkonsumtion, ohälsosamma matvanor, fysisk inaktivitet, och rökning. Dessa ohälsosamma levnadsvanor ökar risken för icke-smittsamma sjukdomar och påverkar både fysisk och mental hälsa, både på kort och lång sikt. Dessutom förekommer dessa ohälsosamma levnadsvanor ofta samtidigt, vilket ytterligare ökar risken för negativa konsekvenser. Därför är det viktigt att stödja hälsosamma levnadsvanor under studieåren för att minska kort- och långsiktiga hälsorisker. Digitala interventioner för att stödja beteendeförändring har visat lovande resultat, men det saknas kunskap om effekterna av de enskilda komponenterna som interventionerna består av, samt om interventioner som riktar sig mot flera levnadsvanor samtidigt.

Syfte

Denna avhandling syftade till att designa och utvärdera en digital intervention för flera levnadsvanor, kallad Buddy, som riktar sig mot svenska universitets- och högskolestudenters alkoholkonsumtion, matvanor, fysiska aktivitet och rökning. De fyra delstudierna undersökte studenters perspektiv på hälsa och välbefinnande, utvärderade effekten av Buddys komponenter, analyserade studenternas interaktioner med Buddy, och deras upplevelser av beteendeförändringsprocessen.

Studier

I Studie I användes en kvalitativ design med digitala intervjuer för att undersöka studenters upplevelser av hälsa, hälsorelaterade beteenden och beteendeförändring. Analysen av transkripten följde den fenomenologiska hermeneutiska traditionen. Resultaten visar att studenter gör val som är påverkade av studentkulturen och akademiska krav. Studenter möter också nya hälsorelaterade utmaningar, till exempel studierelaterad stress och att hantera en begränsad budget. Dessa influenser gör det ibland utmanande att prioritera hälsosamma rutiner, och studenter strävar efter att förbättra akademiska prestationer samtidigt som de njuter av studentlivet. När studenterna går vidare genom sina akademiska år utvecklar de strategier för att bibehålla sin hälsa och livskvalitet, och blir gradvis mer självständiga och självsäkra i sina hälsorelaterade val.

I Studie II användes en faktoriell randomiserad studiedesign för att estimera effekten av komponenterna i Buddy interventionen på levnadsvanor. Resultaten visade att tillgång till Buddys komponenter förbättrar alkoholkonsumtion, frukt- och grönsakskonsumtion, fysisk aktivitet, rökvanor och stress. Alla komponenter, förutom målsättningskomponenten, visade individuella fördelar för minst en levnadsvana. Större effekter observerades när komponenterna kombinerades. Dock ledde tillgång till vissa komponenter också till ökad konsumtion av söta drycker, godis, snacks samt ökat BMI.

I Studie III användes en multipel design för att utforska fidelity till Buddy interventionen genom att få insikter i deltagarnas interaktioner med målsättnings-komponenten. Deltagarna använde Buddy för att sätta mål för både enskilda och multipla levnadsvanor, och anpassade Buddy för att möta deras unika behov av beteendeförändring. Individuella karakteristika var associerade med sannolikheten för att sätta mål eller interagera med utmaningar, samt interaktionen med specifika beteendemål och utmaningar. Det egenförfattade innehållet visade att komponenten främst användes för att förbättra fysisk aktivitet och matvanor. Samtidigt adresserade det även studierelaterade aspekter, mental hälsa, skärmtid och sömnrutiner.

I Studie IV användes en kvalitativ design för att förstå varför studenter valde att delta i Buddy och deras efterföljande upplevelser av beteendeförändringsprocessen. Deltagare från Studie II som hade besvarat den sista uppföljningen intervjuades via telefon. Analysen av transkripten följde den fenomenologiska hermeneutiska traditionen, med fokus på respondenternas berättelser om beteendeförändringsprocessen. Resultaten visar att studiepopulationen kunde beskrivas med sju olika personas som hade varierande intentioner och nivå av engagemang gentemot Buddy och beteendeförändringsprocessen. Resultaten antydde att Buddy var mest effektiv för studenter som stämde in på personan av att ha ett målfokuserat tankesätt, tydliga skäl för förändring, medvetenhet om sina behov, förmågan att tolka information och omsätta reflektion i handling, samt hade den energi som krävdes för att genomföra förändringar.

Slutsatser

Studenters upplevelser av hälsa och beteendeförändring kan beskrivas som en transition, en balansakt, liknande att gå på en slak lina, där studenter söker en hälsosam balans medan de navigerar genom sina studieår. När de erbjuds digitalt stöd för beteendeförändring anpassar studenterna stödet för att möta sina behov, även utöver de inkluderade levnadsvanorna. Innehållet i det digitala stödet påverkar effekten, och effekten av de enskilda komponenterna och deras kombinationer är heterogen för de olika levnadsvanorna. Att framgångsrikt stödja studenter mot hälsosammare levnadsvanor med hjälp av digitala interventioner beror på samspelet mellan det digitala formatet och interventionsinnehållet samt studenternas individuella förväntningar, behov, färdigheter och livssituation.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2025. p. 55
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1948
National Category
Public Health, Global Health and Social Medicine
Identifiers
urn:nbn:se:liu:diva-211272 (URN)10.3384/9789180758437 (DOI)9789180758420 (ISBN)9789180758437 (ISBN)
Public defence
2025-02-28, Berzeliussalen, Building 463, Campus US, Linköping, 13:00 (Swedish)
Opponent
Supervisors
Note

Funding agency: The Swedish Research Council for Health, Working Life and Welfare (Forte)

Available from: 2025-01-31 Created: 2025-01-31 Last updated: 2026-03-13Bibliographically approved

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Åsberg, KatarinaLundgren, OskarOlsson, HannaHenriksson, PontusEldh, Ann CatrineBendtsen, PrebenBendtsen, Marcus

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