Here is the design of a clinical trial:

Official Title: Efficacy of a Modified Banxia Xiexin Decoction (BXD) for the "Wei-Pi" Syndrome (Postprandial Distress Syndrome): a Randomized, Waitlist Controlled Trial

Included conditions:
- Postprandial Distress Syndrome

Study Armgroups:
- {'label': 'BXD treatment', 'type': 'EXPERIMENTAL', 'description': 'Participants will be diagnosed and treated by Chinese medicine practitioners (CMPs) with at least 5 years of clinical experience. CMPs will differentiate syndrome and prescript herbs in a semi-standardized protocol, which consists of a base Chinese medicine decoction, Banxia Xiexin Decoction (BXD), and the additional syndrome-specific herbs.\n\nThe modified decoction will be prepared in a conventional decocting method at the Chinese medicine pharmacy in the clinic (HKBA-HKU CMCTR) and will be packaged into bags by the auto-decocting machines. Participants will take the decoction twice per day, 5 days per week, for 3 weeks.', 'interventionNames': ['Other: Banxie Xiexin Decoction (BXD)']}
- {'label': 'Waitlist', 'type': 'NO_INTERVENTION', 'description': 'Participants in the waiting list control group will be observed for a three-week waiting period. Rescue medication is not restricted.'}

Interventions:
- {'type': 'OTHER', 'name': 'Banxie Xiexin Decoction (BXD)', 'description': 'A modified Banxie Xiexin Decoction based on Chinese medicine syndrome differentiation.', 'armGroupLabels': ['BXD treatment']}

Primary Outcomes:
- {'measure': 'Change of the Quality of Life Questionnaire for Functional Digestive Disorders', 'description': 'Quality of Life Questionnaire for Functional Digestive Disorders (FDDQL)', 'timeFrame': 'Change from baseline score at 3 weeks.'}

Please estimate the sample size based on the assumption: 
The significance level is set at 0.05, the power is 80%, and a 15% dropout rate is considered.
Sample size
          In our pilot observations, the global score of FDDQL pertaining to the patients who received BXD showed improvements with an effect size of 0.3â0.88. In the current study, the sample size was estimated with an average effect size of 0.6. The sample size required to achieve a statistical difference was estimated to be 22 patients per group (at Î±â=â0.05, powerâ=â80%, with a 95% confidence interval). Taking the dropout rate of 15% into consideration, a sample size of 84 patients (42 patients per group) is preferred. An interim analysis will be conducted to determine the adequacy of the sample size.