Untangling the Puzzle of Digital Health Interventions:Exploring the user-acceptance and effectiveness of digital health interventions based on computerized intervention components

The quest for a healthier life can be nowadays assisted by digital technology, for example, through digital health interventions. These are types of health campaigns based on the use of technology and digital tools, such as smartphones or web applications. These health interventions can be applied in a multitude of scenarios, such as increasing physical activity or promoting healthy eating. Digital health interventions are complex by design and consist of multiple active components that assist the intervention, for instance, sharing information and education, or using monitoring tools. We define computerized intervention components as active intervention components that can be realized by means of a computerized algorithm or software. This thesis investigates the suitability of three such computerized intervention components: coaching-based strategies, social networks, and behaviour change techniques. In doing so, the suitability of these components is tested and discussed by looking at two distinct concepts, namely, the digital health intervention’s user acceptability and effectiveness. In this project, we have designed and developed two digital health interventions including these computerized components. In addition, we have used the rich datasets from two externally organized digital health interventions, to test the components’ suitability. This research combines a multitude of quantitative and qualitative methods: from thematic analysis and focus groups to agent-based modeling, from statistical analysis to the technical development of complex digital interventions, with a shared aim of answering the question of suitability. The core of this thesis is composed of three parts, each of which focuses on answering the suitability question for the three computerized intervention components of interest. Overall, the work presented in this thesis provides new insights into the complex field of digital health interventions. In addition, our studies offer a set of practical design tips for developers of similar systems, based on the discovered user preferences and concerns. The three investigated components have been applied in previous research in multiple health campaigns, and this thesis presents additional knowledge about their contribution to effective and user-acceptable interventions. We have tackled a small piece of the complex puzzle of developing successful digital health interventions, however, we do expect that this work contributes to the further maturity of advanced interventions.