BackgroundAsthma is a chronic disease requiring effective self-management to control it and prevent mortality. The use of theory-informed digital interventions promoting asthma self-management is increasing. However, there is limited knowledge concerning how and to what extent psychological theory has been applied to the development of digital interventions, or how using theory impacts outcomes.ObjectiveThe study aimed to examine the use and application of theory in the development of digital interventions to enhance asthma self-management and to evaluate the effectiveness of theory-based interventions in improving adherence, self-management, and clinical outcomes.MethodsElectronic databases (CENTRAL, MEDLINE, EMBASE, and PsycINFO) were searched systematically using predetermined terms. Additional studies were identified by scanning references within relevant studies. Two researchers screened titles and abstracts against predefined inclusion criteria; a third resolved discrepancies. Full-text review was undertaken for relevant studies. Those meeting inclusion criteria were assessed for risk of bias using the Cochrane Collaboration tool. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Study outcomes were classified as medication adherence, self-management, asthma control, clinical markers of health, quality of life, other quality of life outcomes, and health care utilization. Effectiveness was calculated as an average outcome score based on the study’s reported significance. The Theory Coding Scheme (TCS) was used to establish the extent to which each intervention had applied theory and which theoretical constructs or behavioral determinants were addressed. Associations between TCS scores and asthma outcomes were described within a narrative synthesis.ResultsFourteen studies evaluating 14 different digital interventions were included in this review. The most commonly cited theories were Social Cognitive Theory, Health Belief Model, and Self-Efficacy Theory. A greater use of theory in the development of interventions was correlated with effective outcomes (r=.657; P=.01): only the 3 studies that met >60% of the different uses of theory assessed by the TCS were effective on all behavioral and clinical outcomes measured. None of the 11 studies that met ≤60% of the TCS criteria were fully effective; however, 3 interventions were partially effective (ie, the intervention had a significant impact on some, but not all, of the outcomes measured). Most studies lacked detail on the theoretical constructs and how they were applied to the development and application of the intervention.ConclusionsThese findings suggest that greater use of theory in the development and application of digital self-management interventions for asthma may increase their effectiveness. The application of theory alone may not be enough to yield a successful intervention, and other factors (eg, the context in which the intervention is used) should be considered. A systemati...