Here is the design of a clinical trial:

Official Title: Cognitive Behavioral Therapy to Optimize Post-Operative Recovery (COPE): A Randomized Controlled Trial

Included conditions:
- Pain, Postoperative
- Pain, Acute
- Pain, Chronic
- Fractures, Closed
- Fractures, Open

Study Armgroups:
- {'label': 'Intervention - CBT', 'type': 'EXPERIMENTAL', 'description': 'Participants in this arm will receive cognitive behavioural therapy (CBT). Participants will complete a series of online modules via a mobile application in addition to standard of care for their fracture injury. Participants will be assigned a dedicated CBT therapist, and receive feedback and support from their therapist via in-app messaging. The CBT program will last approximately 6-8 weeks.', 'interventionNames': ['Behavioral: Cognitive Behavioural Therapy']}
- {'label': 'Control', 'type': 'NO_INTERVENTION', 'description': 'Participants in the control arm of the study will receive standard of care treatment for their fracture(s) but will not receive any Cognitive Behavioral Therapy.'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Cognitive Behavioural Therapy', 'description': "Participants who are randomized to the CBT intervention will be encouraged to begin CBT immediately following randomization. The CBT intervention will focus on addressing maladaptive beliefs related to pain and recovery as well as teaching skills to enhance coping and management of pain symptoms. The specific focus of CBT sessions will be informed by each individual patient's responses to baseline questionnaires. All other aspects of post-operative care will be at the discretion of participant's surgeon.", 'armGroupLabels': ['Intervention - CBT'], 'otherNames': ['CBT']}

Primary Outcomes:
- {'measure': "The prevalence of moderate to severe Persistent Post-Surgical Pain at 12 months' post-fracture", 'description': "The primary outcome is PPSP according to the World Health Organization's (WHO) proposed definition.\n\nThe WHO's definition requires 4 criteria for the diagnosis of PPSP: 1) Pain that began after surgery or a tissue trauma is experienced; 2) The pain is in an area of preceding surgery or tissue trauma, 3) The pain persisted for at least three months after the initiating event, and 4) The pain is not better explained by an infection, a malignancy, a pre-existing pain condition or any other alternative cause.", 'timeFrame': '12 months post-fracture'}

Please estimate the sample size based on the assumption: 
The study is powered at 80% with a significance level (alpha) of 0.05. A 20% loss to follow-up is anticipated.
Sample size determination
          The choice of sample size is based on a comparison of CBT versus usual care for the primary outcome of the prevalence of moderate to severe persistent post-surgical pain over 12Â months post-fracture (Table 2). The anticipated rate of moderate to severe persistent pain is 67%, based on findings from 1218 patients with open extremity fractures enrolled in the FLOW trial, and followed for 1Â year [11]. If we select a control group event rate of 50% and assume a 20% relative risk reduction with CBT, our required sample size per arm is 408. We will recruit 500 participants/arm, for a total of 1000 participants, to accommodate up to a 20% loss to follow-up.Table 2Sample size per arm (80% study power, alphaâ=â0.05). Difference in the proportion of persistent post-surgical pain, between treatment and control groupsRelative risk reduction in moderate to severe persistent pain15%20%25%Proportion of moderate to severe persistent pain in control group (p1)40%104958937645%86648831350%71940826255%600342221
          Table 2 shows the number of participants required per arm across a range of plausible baseline risks in the control group and risk differences of persistent post-surgical pain between treatment and control groups. Bolded numbers represent sample sizes/arm for which the trial is adequately powered to detect clinically important differences.