Here is the design of a clinical trial:

Official Title: The Navigator Trial

Included conditions:
- Opioid Use
- Opioid Dependence
- Opioid Abuse
- Opioid-Related Disorders

Study Armgroups:
- {'label': 'Peer Navigator', 'type': 'OTHER', 'description': 'Current standard of care', 'interventionNames': ['Behavioral: Peer Navigator Intervention']}
- {'label': 'Social Worker', 'type': 'OTHER', 'description': 'Current standard of care', 'interventionNames': ['Behavioral: Social Work Intervention']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Peer Navigator Intervention', 'description': 'A peer navigator delivers an intervention to current drug users and uses their own training and real- life experiences to help people meet their goals.', 'armGroupLabels': ['Peer Navigator']}
- {'type': 'BEHAVIORAL', 'name': 'Social Work Intervention', 'description': 'A hospital social workers uses their own previous training to help people meet their goals.', 'armGroupLabels': ['Social Worker']}

Primary Outcomes:
- {'measure': 'The proportion of participants who are admitted to a formal addiction treatment program within thirty days following the initial ED visit.', 'description': 'Engagement in addiction treatment will be defined as the proportion who are admitted to a formal addiction treatment program within thirty days following the initial ED visit. The research team will be using BHDDH and Prescription Drug Monitoring Program (PDMP) records. The BHDDH database contains information on all admissions to publicly funded substance abuse treatment programs in the state. The RI PDMP manages a database that contains information on all prescriptions for schedule II-IV substances filled in the state. The database is updated daily; all pharmacies are required to report prescriptions within 48-hours of the fill date. All records will be linked deterministically to participant data using identifiable information (e.g., name, social security number) within the Stronghold computing environment, a HIPAA-compliant server maintained by the team at Brown University.', 'timeFrame': '30 days'}
- {'measure': 'The proportion of participants who are treated in any Rhode Island ED for an opioid overdose at any time during the 18-month follow-up period following the initial ED visit.', 'description': 'The proportion of participants who are treated in any Rhode Island ED for an opioid overdose at any time during the 18-month follow-up period following the initial ED visit, will be assessed by first accessing the electronic medical records (EMRs) of the 12 EDs in Rhode Island (RI) through the Rhode Island Quality Institute Statewide Health Information Exchange. This unified data system provides access to EMR data from all major health systems in RI, capturing repeat visits for an opioid overdose that occur in all 12 EDs in RI. Secondly the research team will query the RI Department of Health (RIDOH) Opioid 48-Hour Overdose Surveillance System which mandates all suspected opioid overdose cases presenting to an RI hospital be reported to the department within 48 hours. This data source will capture recurrent overdoses not identified by ICD codes in the unified EMR data system, and also contains additional fields of interest (e.g., pre-existing risk factors for overdose).', 'timeFrame': '18 months'}

Please estimate the sample size based on the assumption: 
80% power to detect a twofold increase in treatment engagement; 80% power to detect a 50% relative reduction in the risk of recurrent ED visits for opioid overdose; significance level implied by 95% CI.
Sample size
        Based on preliminary assessments from the study sites, we are assuming that 7% of participants assigned to receive a behavioural intervention from an LCSW will enrol in a formal SUD treatment programme within 30 days of their ED visit. Given this assumption for a sample size of 650 participants, we have at least 80% power to detect a twofold increase in treatment engagement among participants assigned to receive a behavioural intervention from a peer recovery specialist (risk difference: 0.07; 95%âCI 0.02 to 0.12). This twofold increase was identified by community stakeholders as an appropriate benchmark for this outcome. Based on a recent medical record review from one of the study sites and estimates from other studies,20 33 we are assuming that 15% of participants who receive a behavioural intervention from an LCSW will experience a subsequent repeat ED visit for opioid overdose. Given this assumption and our sample, we have at least 80% power to detect a 50% relative reduction in the risk of recurrent ED visits for opioid overdose within 18 months following the initial visit among those assigned to receive a behavioural intervention from a peer recovery specialist (risk difference: 0.075; 95%âCI 0.02 to 0.13).