Table 1 Areas of challenge in assessing engagement and adherence in digital studies in brain health (as identified by the consensus group)

From: Engagement and attrition in digital mental health: current challenges and potential solutions

1. Lack of universally agreed definitions of metrics related to engagement

 • Terms such as usage, engagement, adherence, attrition, and empowerment all have variable definitions in individual studies

 • Raw data are often not reported

2. Lack of evidence of how or whether improved engagement improves outcomes.

 • No clear evidence that increased engagement improves outcomes

 • No clear evidence of a dose effect of engagement or the optimal dose needed

 • Difficulties of translating engagement from the research to real-world settings

 • No clear evidence on the exact mechanisms of engagement, individual effective use patterns and attrition

 • Interaction with mental health

 • Attrition

 • Lack of adverse event reporting

3. User involvement in developing and delivering digital health interventions

 • User involvement can occur in different ways and levels of intensity and inclusivity

 • Reporting of user involvement is variable

 • User centred design may improve engagement and outcomes, but more direct evidence is needed