Engagement and retention in digital mental health interventions: a narrative review

Abstract Background While many digital mental health interventions (DMHIs) have been shown to be effective, such interventions also have been criticized for poor engagement and retention rates. However, several questions remain about how users engage with DMHIs, how to define engagement, and what factors might help improve DMHI engagement. Main abstract In this narrative review, we show that although DMHIs are criticized for poor engagement, research suggests engagement rates are quite variable across studies and DMHIs. In some instances, engagement rates are high, even in real-world settings where there is evidence of a subset of users who could be considered ‘superusers’. We then review research on the barriers and facilitators to DMHI engagement, highlighting that qualitative research of users’ perceptions does not always align with quantitative research assessing relationships between these barriers/facilitators and actual engagement with DMHIs. We also introduce several potential issues in conceptualizations of DMHI engagement that may explain the mixed findings, including inconsistent definitions of engagement and assumptions about linear relationships between engagement and outcomes. Finally, we outline evidence suggesting that engagement with DMHIs is comparable to mobile application use broadly as well as engagement with more traditional forms of mental health care (i.e., pharmacological, psychotherapy). Conclusions In order to increase the number of people who can benefit from DMHIs, additional research on engagement and retention is necessary. Importantly, we believe it is critical that this research move away from several existing misconceptions about DMHI engagement. We make three recommendations for research on DMHI engagement that we believe, if addressed, are likely to substantially improve the impact of DMHIs: (1) the need to adopt a clearly defined, common definition of engagement , (2) the importance of exploring patterns of optimal engagement rather than taking a ‘one size fits all’ approach, and (3) the importance of defining success within DMHIs based on outcomes rather than the frequency or duration of a user’s engagement with that DMHI.