Here is the design of a clinical trial:

Official Title: Evaluation of Stepped PrEP (Pre-exposure Prophylaxis) Adherence Support for Young South African Women Using a SMART Design

Included conditions:
- HIV/AIDS

Study Armgroups:
- {'label': 'WhatsApp Group', 'type': 'EXPERIMENTAL', 'description': 'Participants will be assigned to participate in a WhatsApp Group', 'interventionNames': ['Behavioral: WhatsApp Group']}
- {'label': '2-way SMS', 'type': 'EXPERIMENTAL', 'description': 'Participants will be assigned to receive weekly 2-way SMS initiated by the study team', 'interventionNames': ['Behavioral: 2-way SMS']}
- {'label': '2-way SMS and monthly counseling sessions', 'type': 'EXPERIMENTAL', 'description': 'Participants will be assigned to receive weekly 2-way SMS initiated by the study team and monthly counseling sessions', 'interventionNames': ['Behavioral: 2-way SMS', 'Behavioral: Monthly counseling sessions']}
- {'label': '2-way SMS and drug level feedback', 'type': 'EXPERIMENTAL', 'description': 'Participants will be assigned to receive weekly 2-way SMS initiated by the study team and drug level feedback', 'interventionNames': ['Behavioral: 2-way SMS', 'Behavioral: Drug level feedback']}
- {'label': 'WhatsApp Group and monthly counseling sessions', 'type': 'EXPERIMENTAL', 'description': 'Participants will be assigned to participate in a WhatsApp Group and monthly counseling sessions', 'interventionNames': ['Behavioral: WhatsApp Group', 'Behavioral: Monthly counseling sessions']}
- {'label': 'WhatsApp Group and drug level feedback', 'type': 'EXPERIMENTAL', 'description': 'Participants will be assigned to participate in a WhatsApp Group and drug level feedback', 'interventionNames': ['Behavioral: WhatsApp Group', 'Behavioral: Drug level feedback']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'WhatsApp Group', 'description': 'Participants will receive peer adherence support through WhatsApp groups', 'armGroupLabels': ['WhatsApp Group', 'WhatsApp Group and drug level feedback', 'WhatsApp Group and monthly counseling sessions']}
- {'type': 'BEHAVIORAL', 'name': '2-way SMS', 'description': 'Participants will receive healthcare worker adherence support through 2-way SMS', 'armGroupLabels': ['2-way SMS', '2-way SMS and drug level feedback', '2-way SMS and monthly counseling sessions']}
- {'type': 'BEHAVIORAL', 'name': 'Drug level feedback', 'description': 'Participants will receive adherence counseling based on tenofovir drug levels', 'armGroupLabels': ['2-way SMS and drug level feedback', 'WhatsApp Group and drug level feedback']}
- {'type': 'BEHAVIORAL', 'name': 'Monthly counseling sessions', 'description': 'Participants will receive monthly counseling on a variety of issues that may be impacting their PrEP adherence', 'armGroupLabels': ['2-way SMS and monthly counseling sessions', 'WhatsApp Group and monthly counseling sessions']}

Primary Outcomes:
- {'measure': 'PrEP Adherence', 'description': 'Evaluation of the proportion of young women who adhere well to PrEP in each of the intervention arms.', 'timeFrame': '9 months'}

Please estimate the sample size based on the assumption: 
96% power for 20% difference; 84% power for 15% difference; 79-96% power for 30% difference.
Sample size and statistical power
          We estimate that enrolling up to 500 participants (with approximately 350 retained through their Month 9 study visit) will provide 96% power to detect an approximately 20% difference in the proportion of participants with TFV-DP levels â¥700 fmol/punch between the two-way SMS and WhatsApp group arms at the Month 9 study visit. With 350 participants at the Month 9 study visit, we would have 84% power to detect a 15% difference in TFV-DP levels between the two mHealth interventions. Assuming that between 70â105 participants in each primary intervention arm are re-randomized at the Month 3 visit, we will have 79â96% power in each primary intervention arm to detect a 30% difference in TFV-DP levels at the Month 9 visit in the monthly counseling arm compared with the drug-level feedback counseling arm.