Here is the design of a clinical trial:

Official Title: Nonpharmacologic Pain Management in FQHC Primary Care Clinics

Included conditions:
- Low Back Pain
- Chronic Pain

Study Armgroups:
- {'label': 'Brief Pain Teleconsult', 'type': 'EXPERIMENTAL', 'description': 'Participants randomized to Brief Pain Teleconsult will receive the brief teleconsult intervention in Phase 1 (1-12 weeks) Responder status to the Phase 1 treatment will be examined at the 12 week assessment. Participants determined to be non-responders will receive the Telehealth Physical Therapy intervention. Responders receive no additional treatment.', 'interventionNames': ['Behavioral: Brief Pain Teleconsult', 'Behavioral: Telehealth Physical Therapy']}
- {'label': 'Brief Pain Teleconsult plus Telehealth Physical Therapy', 'type': 'EXPERIMENTAL', 'description': 'Participants randomized to Brief Pain Teleconsult plus Telehealth Physical Therapy will receive the brief teleconsult intervention in Phase 1 followed by the 10-week physical therapy intervention. No additional treatment is provided after the 12 week assessment.', 'interventionNames': ['Behavioral: Brief Pain Teleconsult', 'Behavioral: Telehealth Physical Therapy']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Brief Pain Teleconsult', 'description': 'The Brief Pain Teleconsult intervention includes 2 sessions provided by a licensed physical therapist over about 1 week. The sessions focus on pain education from a biopsychosocial perspective that is designed to address negative pain appraisals and catastrophizing thoughts, providing advice to be active and engage in exercise and physical activity, and reassurance that activity is beneficial and safe.', 'armGroupLabels': ['Brief Pain Teleconsult', 'Brief Pain Teleconsult plus Telehealth Physical Therapy']}
- {'type': 'BEHAVIORAL', 'name': 'Telehealth Physical Therapy', 'description': 'The Telehealth Physical Therapy intervention involves weekly telehealth sessions provided over 10 weeks. Telehealth Physical Therapy is provided by a licensed physical therapist. Key components of the intervention include reinforcing biopsychosocial education messages and developing an exercise and physical activity program using cognitive behavioral principles such as goal setting and positive reinforcement. Pain coping strategies including mindful breathing and progressive relaxation techniques will be included.', 'armGroupLabels': ['Brief Pain Teleconsult', 'Brief Pain Teleconsult plus Telehealth Physical Therapy']}

Primary Outcomes:
- {'measure': 'PEG-3', 'description': 'The PEG-3 measure includes 3 items evaluating 1) pain severity, and interference of pain with 2) enjoyment and 3) general activity. Item response options range from 0-10. The PEG-3 score is expressed as the mean of all item scores with higher scores indicating greater pain impact', 'timeFrame': '12 weeks'}

Please estimate the sample size based on the assumption: 
80% retention across follow-ups, significance level (two-sided α) = 0.05, power = 80% or 90%, serial correlations R=0 for repeated PEG assessments, intraclass correlation coefficients (ICCs) for outcomes across therapists with a mean around 0.08, and a denominator df of 7 for statistical inference.
Sample size Justification
        We based power calculations on the following assumptions: (1) 80% retention across follow-ups, based on our experience in prior trials,46 85 (2) minimum important difference (MID) for the PEG is 1.0 (SD=2.5),68 86 which translates to 40% of 1 SD change, (3) A projected sample size of 500 participants or 250 per group and (4) a conservative assumption of serial correlations R=0 for repeated PEG assessments. For exploratory analyses of treatment effects across therapists as random effects, we assume there will be a total of eight therapists who will see similar numbers of patients and we conservatively assume a denominator df of 7 (8â1) for statistical inference. Previous studies have noted variable intraclass correlation coefficients (ICCs) for outcomes across therapists providing psychological interventions with a mean around 0.08.87â89 We note that the ICC in this study may be lower because the same therapists will treat subjects in both arms, but we are not aware of previous data that would confirm this conjecture. With these assumptions, table 6 provides conservative estimates of the minimum treatment effects in the full cohort that are detectable with the fixed and random effects approaches with 80% or 90% power and two-sided Î±=0.05. These calculations indicate excellent power to detect the MID for the PEG under a fixed effects approach. Adequate power to detect the MID is possible under a random effects approach, but is not assured with high confidence.
        
          Table 6
          
            Minimum detectable treatment effects on the primary PEG outcomeâanalyses of the full study cohort
          
          
            
              
                Power
                Fixed effects approach
                Random effects approach
              
              
                ICC=0.04
                ICC=0.08
                ICC=0.12
              
            
            
              
                80%
                0.70
                0.99
                1.14
                1.27
              
              
                90%
                0.81
                1.15
                1.32
                1.48
              
            
          
          
            
              ICC, intraclass correlation coefficient; PEG, pain, enjoyment and general activity.