Lay summary
Predicting how innovative mental health service delivery impacts on existing service ecosystems is multifactorial and complex, requiring economic analysis alongside examination of effectiveness and acceptability of the new service and assessment of other service use adjustments. It is unclear how innovative community-based services impact on service ecosystems that include concurrent service use of primary care, ED, ambulance, police, community mental health services and voluntary agencies. This research informs an ecosystems service modelling methodology that includes economic analysis, localised service mapping and multiple service use informed by end user and commissioning priorities. Mental health services are oversubscribed, and people who need services face lengthy waits. Mental health and addictions policy calls for sustainable service transformation through innovation, digital technologies and improved access and choice. This research maps impacts on existing services to develop an ecosystem service modelling approach based around one new service.