Table 1.

Perception of factors influencing engagement with health apps.

COM-Ba model component, TDFb construct, and factors				Description
Psychological capability
	Knowledge
		User guidance	Instructions on how to effectively use a health app
		Statistical information	A visual or numerical summary of progress or quantification of the behavior
		Health information	Educational information related to health and well-being aspects
	Memory, attention, and decision processes
		Reduced cognitive load	The app is not too time-consuming, is easy to use, and requires minimal input
		Reminders	Preferably customizable notification-type messages
	Behavior regulation
		Self-monitoring	The ability of the app to support self-regulation of the target behavior
		Routines	The ability to support routine or habit formation
		Safety netting	Retaining the app for a potential upcoming event in the future
		Stepping-stone	App as a first step in the behavior change process
Physical opportunity
	Environmental resources
		Tailoring	Innovative features, adaptability, and interactive and 2-way communication between the app and user
Social opportunity
	Social influences
		Peer support	Including social interaction with users with similar needs within the app or within their community; a choice to connect to social media platforms, competitions, and challenges with others or with themselves
		Social support (practical)	Possibility to contact health professionals and practitioners within the app
Reflective motivation
	Beliefs about capabilities
		Self-confidence	Perceived capability to change one’s behavior using an app
	Goals
		Goal setting	Establishing what the user would like to achieve
		Action planning	Establishing how the user would like to achieve set goals
	Beliefs about consequences
		Commitment	The level of commitment while engaging with an app to change the behavior and achieve set goals
Automatic motivation
	Reinforcement
		Feedback	Feedback regarding the user’s performance
		Rewards	Tangible (eg, objects and discounts) and intangible (eg, badges and certificates) rewards in response to the user’s effort and gamification elements
		Encouragement	Additional ways to provide reinforcement (eg, encouraging messages)
	Emotions
		Positive emotions	Triggered by the included user guidance, statistical information, additional health information, embedded professional support, community networking possibilities, tracking features, and rewards
		Negative emotions	Triggered by lack of user guidance, invasive push notifications, cognitive overload, and unrevealed in-app costs
		Mixed emotions	Triggered by reminders

^aCOM-B: Capability, Opportunity, Motivation–Behaviour.

^bTDF: Theoretical Domains Framework.