Health behaviour applications (also referred to as "apps") have the potential to provide several advantages for motivating behaviour change for health and well-being. Finding ways to increase and sustain health promoting behaviour changes has been a challenge during health app development. Gamification, which is the use of game elements in a non-game situation, shows promise and has proven effective in many fields. However, key questions remain concerning how to use gamification in apps to modify health behaviour, especially to support adherence to dietary pattern recommendations. To investigate and summarize the current evidence, a systematic review of the totality of evidence from clinical trials and observational studies will be conducted to capture and distinguish the types of gamification strategies that may be most effective in improving and sustaining health promoting behaviours to inform future health behaviour app development.

Background: Studies on health behaviours such as physical activity and smoking cessation (behaviour change) have indicated that gamification is an effective tool for engagement and behaviour change, especially when multiple different competitive elements are used including: a ranking system, badges and achievements, points, social media interaction, and leveling up. Gamification is the use of game elements in a non-game environment to invoke behaviour change. The majority of health-focused gamification investigations are currently conducted using web or mobile-based delivery platforms in adults focusing on physical activity. Access to these web and mobile based applications through smartphones, tablets and computers has grown rapidly. In 2016, 94% of Canadians had home internet access, with 88% reporting that they use a smartphone for personal use. Moreover, a recent survey in the US found that 73% of those with, or at risk of cardiovascular disease, have a smartphone and 43% use a health-related application to track progress towards a health goal. While research on mobile-based app use for modifying diet is promising, the effectiveness of using gamification in apps for sustaining dietary pattern adherence is unclear. An investigation and summary of the current types of gamification strategies that may be most effective is important to inform and aid future app development. The ultimate aim of this research investigation is to inform the development of the PortfolioDiet.app, a dietary pattern adherence application for reducing LDL-cholesterol in individuals at risk for cardiovascular disease.

Objective: To conduct a systematic review investigating the gamification strategies used in applications for long term behaviour change, with a specific focus on dietary pattern adherence in adults.

Design: A systematic review of the literature will be conducted according to the Cochrane Handbook for Systematic Reviews of Interventions and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

Data sources: MEDLINE, EMBASE, and The Cochrane Central Register of Controlled Trials (Clinical Trials; CENTRAL) will be searched using appropriate search terms supplemented by hand searches of references of included studies.

Study selection: The investigators will include prospective cohort studies and controlled trials. Studies will be included if they are >= 2-months in duration and assess the relation of different gamification strategies used in health behaviour applications with adherence to the health intervention, participant engagement with using the application, and/or the intended health outcome. There will be no language restrictions.

Data extraction: Two or more investigators will independently extract relevant data and assess risk of bias using the Cochrane Risk of Bias Tool. All disagreements will be resolved by consensus.

Outcomes: The primary outcome will be adherence to the intervention associated with use of the application, such as, but not limited to: physical activity, smoking cessation, increasing fruit and vegetable intake, improving healthy food index score. Secondary outcomes will include participant engagement with use of the application. This adherence to using the application may be determined based on number of using days using the application compared to intended number of days of application usage. Observation of a significant change in the intended health outcome, such as, blood glucose, HbA1c, blood lipids, weight change [BMI, body weight, waist circumference, will also be assessed.

Data Synthesis: A Microsoft Excel spreadsheet will be used to track the extractions and summarize the qualitative and quantitative data from each study.

Risk of Bias (Quality) Assessment: The risk of bias of each included study will be assessed using the Cochrane Handbook for Systematic Reviews of Interventions. This will be done in relation to evaluating the criteria for assessing risk as either low, high or uncertain risk of bias as identified in the Risk of Bias tool.

Knowledge translation plan: The results will be disseminated through interactive presentations at local, national and international scientific meetings and publication. As well as utilized in a publically available web-based application hosted on the Canadian Cardiovascular Society website.

Significance: Gamification has been identified as a promising tool for health promotion. While research directly comparing gamified interventions to non-gamified controls has found beneficial effects on physical activity, or more recently mental health, there is a lack of evidence on investigating gamification for dietary change. As poor health behaviours (i.e. unhealthy diet, smoking, sedentary behaviour) have been repeatedly identified as major contributors to disease burden in Canada and globally, interventions which can target and improve these behaviours over a long term are required. Furthermore, as the generations who have grown up with the internet and app technology begin to age they will seek engaging digital tools to improve health outcomes, and therefore the need for digital health interventions that are effective at improving and sustaining beneficial health behaviours will only continue to grow.](streamdown:incomplete-link)

Inclusion Criteria for controlled trials:

• Randomized and non-randomized controlled intervention studies in humans
• Gamification intervention
• Presence of an adequate comparator, such as standard of care or an application without gamification components
• Intervention duration >=2 months
• Viable outcome data

Inclusion Criteria for prospective cohort studies:

• Prospective cohort studies
• Duration >= 2-months
• Assessment of the exposure of gamification used in a health behaviour application
• Ascertainment of viable outcome data by level of exposure

Exclusion Criteria for controlled trials:

• Lack of an adequate comparator
• Non-health behaviour application

Exclusion Criteria for prospective cohort studies:

• Ecological, cross-sectional, or retrospective observational studies
• Intervention studies

All adults (>=18 years), regardless of health status.