Here is the design of a clinical trial:

Official Title: Procalcitonin-guided Initiation of Antibiotics in AECOPD Inpatients: a Multicenter Randomized Controlled Trial

Included conditions:
- Procalcitonin
- Chronic Obstructive Pulmonary Disease

Study Armgroups:
- {'label': 'PCT-guided antibiotic therapy (PCT group)', 'type': 'EXPERIMENTAL', 'description': 'Participants in the PCT group will complete a PCT test within 2 hours after randomization and the results will be sent back to the clinician by laboratory through the internal network of the hospital. The prescribing clinician will use the results of the PCT to help guide their antibiotic prescription decision. The detailed recommendations are as follows: if PCT\\<0.1ng/ml，strongly discouraged；if PCT (0.1-0.25ng/ml) and no sputum purulence, discouraged; if PCT (0.1-0.25ng/ml) and sputum purulence, Recommended; PCT\\>0.25 ng/ml, Strongly recommended.', 'interventionNames': ['Drug: procalcitonin-guided antibiotic therapy']}
- {'label': 'Guideline-guided antibiotic therapy (guideline group)', 'type': 'ACTIVE_COMPARATOR', 'description': 'Participants in the guideline group will also need to complete a PCT test within 2 hours after randomization, however, the laboratory will save the results and do not sent back to the clinician. The clinician will make an antibiotic prescribing decision on the basis of the recommendations of GOLD guideline. The guideline recommend the following patients to receive antibiotic therapy. Patients with exacerbations of COPD who have three cardinal symptoms: increase in dyspnea, sputum volume, and sputum purulence; have two of the cardinal symptoms, if increased purulence of sputum is one of the two symptoms; or require mechanical ventilation (invasive or noninvasive).', 'interventionNames': ['Drug: guideline-guided antibiotic therapy']}

Interventions:
- {'type': 'DRUG', 'name': 'procalcitonin-guided antibiotic therapy', 'description': 'In procalcitonin group, clinican make a decision of antibiotic precription based on the results of procalcitonin.', 'armGroupLabels': ['PCT-guided antibiotic therapy (PCT group)']}
- {'type': 'DRUG', 'name': 'guideline-guided antibiotic therapy', 'description': 'In guideline group, clinican make a decision of antibiotic precription based on the recommendations of GOLD guideline.', 'armGroupLabels': ['Guideline-guided antibiotic therapy (guideline group)']}

Primary Outcomes:
- {'measure': 'Antibiotic prescription rate', 'description': 'proportion of patients receiving antibiotics for AECOPD', 'timeFrame': 'within 30 days post randomization'}
- {'measure': 'Treatment success rate', 'description': 'Treatment success is defined as cure (a complete resolution of signs and symptoms associated with the exacerbation) or improvement (a resolution or reduction of the symptoms and signs associated with the exacerbation, without new symptoms or signs).', 'timeFrame': 'day 30 post randomization'}

Please estimate the sample size based on the assumption: 
The study uses a 5% significance level and 90% power for detecting the difference in antibiotic consumption. For demonstrating non-inferiority, it uses a one-sided significance level of 0.05% and 80% power. A drop-out rate of 20% is assumed for both endpoints.
Sample size
        This study is designed to have sufficient power to detect a 20% reduction from an estimated 70% that consume antibiotics for the AECOPD during the 30 days following randomisation. In the Schuetzâs RCT to compare PCT guide antibiotic prescription with guideline therapy, subgroup analysis in patients with AECOPD shown that the 30-day prescription rate of guideline group and PCT group was 69.9% and 48.7%, respectively.15 Detecting a difference in proportions between 0.70 and 0.50 at the 5% significance level with 90% power requires a total of 242 participants. Assuming a drop-out rate of 20%, we will need to enrol 302 participants. In addition, we aim to have sufficient power to demonstrate that participants managed with PCT-guided strategy are non-inferior, compared with those managed with guideline recommendations, in terms of treatment success rate at day 30 post randomisation. A limited number of studies have reported the success rate at day 30 after randomisation in patients with AECOPD.16 23 According to prior trials in terms of hospitalised patients with AECOPD, Stolz et al16 reported the short-term treatment success rate as 83.9% (from 14 to 21 days post randomisation) and Prins et al23 determined the treatment failure rate at day 30 after randomisation as 20.3%. Based on these data and assuming a treatment success rate of 0.8 at day 30 following randomisation, a non-inferior margin of 0.1,24 based on a one-sided significance level of 0.05% and 80% power, would require 396 participants. Again, with a drop-out rate of 20%, 495 participants will need to be included. Finally, considering these two primary endpoints, we will aim to recruit 500 participants in total to the study.