Here is the design of a clinical trial:

Official Title: Efficacy and Safety of Transcutaneous Electrical Acupoints Stimulation for Preoperative Anxiety in Thoracoscopic Surgery: Study Protocol for a Randomized Controlled Trial

Included conditions:
- Acupuncture Therapy
- Preoperative Period
- Anxiety
- Thoracoscopic Surgery

Study Armgroups:
- {'label': 'TEAS group', 'type': 'EXPERIMENTAL', 'description': '30 minutes TEAS therapy on DU20, EX-HN3, LI4, LR3 once per day for three days before surgery.', 'interventionNames': ['Device: TEAS']}
- {'label': 'Control group', 'type': 'SHAM_COMPARATOR', 'description': 'The control group selects the same acupoints as the TEAS group and other intervention measures are the same as the TEAS group except for the current intensity is set to 0-mA.', 'interventionNames': ['Device: Sham TEAS']}

Interventions:
- {'type': 'DEVICE', 'name': 'TEAS', 'description': 'The self-adhesive gel electrode pad will be placed at the center of DU20 (Baihui), EX-HN3 (Yintang) and both sides of LI4 (Hegu), LR3 (Taichong) in strict accordance with the World Health Organization Standardized Acupuncture Location. Electric stimulation will be used with a TEAS apparatus (HANS200A Beijing Huawei Co., LTD.) . The frequency of the electrical stimulation will be set as alternating 2/100Hz to relieve anxiety. The current intensity will be adjusted individually, starting at 1 mA and increasing gradually until the patient can perceive and tolerate it (preferably slight twitching of local muscles without pain).', 'armGroupLabels': ['TEAS group']}
- {'type': 'DEVICE', 'name': 'Sham TEAS', 'description': 'The STEAS group selects the same acupoints as the TEAS group and other intervention measures are the same as the TEAS group except for the current intensity is set to 0-mA. The acupuncturist responsible for the operation will tell patients in STEAS group that this is a type of stimulus without perception.', 'armGroupLabels': ['Control group']}

Primary Outcomes:
- {'measure': 'Score change of Generalized Anxiety Scale (GAD-7)', 'description': "Add the scores of each of the 7 items to get the total score; among them, 0-4 points for no anxiety, 5-9 points for possible mild anxiety, 10-14 points for possible moderate anxiety, 15 Scores above are likely to have severe anxiety. The GAD-7 scores' Change between three days before and the day before surgery will be recorded.", 'timeFrame': 'up to 3 days before surgery'}

Please estimate the sample size based on the assumption: 
Test level bilateral α=0.05, test power 1−β = 0.9, 15% probability of lost to follow-up
Sample size
        Primary outcome indicator in this trial is the GAD-7 score variation between the day before VATS with the baseline. The sample size was calculated on the grounds of our preliminary trial (online supplemental material 1). Reference for optimal effectiveness in clinical trials of two sample mean comparison, using formula for calculating sample size of clinical trials as follow.
        
          10.1136/bmjopen-2022-067082.supp1
          Supplementary data
          


        
        

n1=n2=2[(uÎ±+uÎ²)Î´/Ï]2+14uÎ±2


        GAD-7 score change in TEAS group increase the divergence between the STEAS group and the SD by 73%. Î´/Ï=0.73, test level bilateral Î±=0.05, test power 1âÎ² = 0.9. Through calculation, each group required sample size is 40 samples. The submitted trial will demand 92 participants to be divided into two groups of 46 in consideration of the 15% probability of lost to follow-up.