Table 2 Definitions and source for implementation domain and construct names identified in the analysis

Intervention Characteristics^a

Evidence, strength, and quality

Awareness of successful pre-existing ED-peer influenced adoption decisions for all vendors, but rural vendors were skeptical about applicability to their settings.

Intervention source

Relative advantage

Rural vendors saw advantages of peers outside of the ED, where urban vendor solely focused on peer advantage in the ED.

Adaptability

Rural sites made more adaptations over time to address peers’ low work volume.

Cost

Rural vendors had greater concerns regarding costs.

External context^b

Target population

Rural vendors did not have resources to fully staff peak overdose admission times or the ability to engage with transferred patients. Patients in rural areas also tended to use drugs other than opioids.

Relational climate

Rural vendor slacked protocols to follow-up with transferred patients.

Policy and legal climate

Privacy laws limited rural vendors' ability to share information with other hospitals where patients were transferred.

Local infrastructure

Rural areas lacked treatment providers for patient referral and options for transportation to referrals were limited.

Inner setting^a

Networks and communication

Rural vendors lacked strong mechanisms for communication between ED staff and peers. Rural providers were often reluctant to have peers see patients.

Culture

Rural peers frequently encountered lack of respect for their lived experience and negative attitudes toward addiction on the part of ED staff.

Implementation climate

Rural vendor experienced difficulties justifying integration of peer services into ED systems and workflows due to low volume of patients eligible for peer services.

Characteristics of individuals^a

Knowledge and beliefs

Rural providers resisted working with peers and patients they served due to pre-existing beliefs.

Implementation process^a

Engaging

Rural vendors had to spend more time identifying external providers to refer patient to. They also spent more time engaging local law enforcement in order to create more work for peers.

Executing

Rural vendors abandoned more components of their initial implementation plans because of staff resistance and low patient volume.