Here is the design of a clinical trial:

Official Title: Efficacy, Safety and Response Predictors of Adjuvant Astragalus Therapy for Diabetic Kidney Disease (READY) - An Open-label Randomised Controlled Trial With Responder Regression Analysis

Included conditions:
- Diabetic Nephropathies
- Diabetic Kidney Disease

Study Armgroups:
- {'label': 'Standard medical care', 'type': 'ACTIVE_COMPARATOR', 'description': 'Angiotensin converting enzyme inhibitor or angiotensin receptor blocker and oral hypoglycemic agents or insulin', 'interventionNames': ['Other: Routine medical care (active comparator)']}
- {'label': 'Add on astragalus powder', 'type': 'EXPERIMENTAL', 'description': '3 grams of water soluble astragalus sachets (equivalent to 15g raw herbs) administrated orally on top of standard medical care for 48 weeks.', 'interventionNames': ['Drug: Astragalus Powder', 'Other: Routine medical care (active comparator)']}

Interventions:
- {'type': 'DRUG', 'name': 'Astragalus Powder', 'description': '3 grams of water soluble astragalus sachets (equivalent to 15g raw herbs) administrated orally on top of standard medical care for 48 weeks.\n\nPatients will have 5 days of medicine per week and will be advised to take the medicine once daily dissolved in boiling water in the first 5 days of the week.', 'armGroupLabels': ['Add on astragalus powder']}
- {'type': 'OTHER', 'name': 'Routine medical care (active comparator)', 'description': 'Angiotensin converting enzyme inhibitor or angiotensin receptor blocker', 'armGroupLabels': ['Add on astragalus powder', 'Standard medical care']}

Primary Outcomes:
- {'measure': 'Change in estimated GFR', 'description': 'Efficacy and safety', 'timeFrame': 'From baseline to 48 weeks after treatment'}
- {'measure': 'Change in spot urine albumin-to-creatinine ratio', 'description': 'Efficacy and safety', 'timeFrame': 'From baseline to 48 weeks after treatment'}

Please estimate the sample size based on the assumption: 
The study aims to be 95% confident (two-sided) that the main study achieves a power of 70% with a nominal power set at 80% (10% power forfeit). An inflation factor (IF) of less than 1.13 is needed. A 15% attrition rate is considered.
Sample size calculation
          Since the primary objective of this trial is to evaluate key clinical outcomes and to perform a preliminary analysis on potential response predictors, we calculated the sample size based on the control of inflation factor (IF) to the estimation of sample size for the subsequent large-scale studies.39 40 One hundred and eighteen patients (around 60 per group) are needed.
          
            
              
                
                  
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          where
          IF=Inflation factor.
          Sucl=SD of upper CI.
          Sobs=Observed SD in pilot study.
          Î±=Chosen confidence level.
          áº=Nominal power set for main study.
          áºâ²=Actual power achieved for main study by using pilot SD for sample size calculation.
          n=Sampleâsize of pilot study.
          N=Sampleâsize of main study.
          Nunadj=Sampleâsize of main study with no adjustment on SD.
          Nadj=Sampleâsize of main study with adjustment on SD.
          The SD used for sample size calculation for large-scale main studies is often underestimated by small-scale pilot studies; therefore, an IF is needed for adjustment in sample size calculation.39 40 IF is calculated based on the size of pilot study and the confidence level of achieving at least the desired power in subsequent main studies. Therefore, the actual achieved power of the main studies depends on the nominal power set for the main study and the IF.
          In order to be 95% confident (two-sided) that the main study achieves a power of 70% with nominal power set at 80% (ie, a 10% power forfeit), the IF should be controlled to less than 1.13. At IF=1.13, a sample size of 100 is therefore needed to attain 95% one-sided confidence that the main studies will achieve the nominal power to test the hypothesis of add-on astragalus could be more effective in stabilising the GFR among patients with DKD when compared with standard care. To allow a 15% attrition rate, a sample size of 118 patients is therefore needed for this pilot study.
          Currently, there is limited evidence on the symptom-based response predictors of astragalus. A general recommendation for power estimation is to have 10 events per variable.41 From the previous systematic review, we estimate that around 60% of patients will have stabilised GFR after receiving astragalus.31 One hundred and eighteen subjects with 15% attrition will power up to six variables for the screening of predictors. A univariable screening on the 11 prespecified potential symptom-based predictors will be conducted to reduce the number of predictors for the subsequent multivariable regression analysis, in order to maximise the power of the regression analysis.