Here is the design of a clinical trial:

Official Title: HomeBase2: An Implementation Trial to Improve Access to Pulmonary Rehabilitation in People With Chronic Obstructive Pulmonary Disease

Included conditions:
- Chronic Obstructive Pulmonary Disease

Study Armgroups:
- {'label': 'Intervention', 'type': 'EXPERIMENTAL', 'description': 'Pulmonary rehabilitation programs assigned to the intervention group will offer eligible participants the choice of participating in an 8-week program of either home-based pulmonary rehabilitation or traditional centre-based pulmonary rehabilitation.', 'interventionNames': ['Behavioral: Choice of home-based or centre-based pulmonary rehabilitation']}
- {'label': 'Control', 'type': 'ACTIVE_COMPARATOR', 'description': 'Pulmonary rehabilitation programs assigned to the control group will offer eligible participants the opportunity to participate in an 8-week centre-based pulmonary rehabilitation program, as per current practice.', 'interventionNames': ['Behavioral: Centre-based pulmonary rehabilitation']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Choice of home-based or centre-based pulmonary rehabilitation', 'description': 'Participants will be offered the choice of HomeBase, a home-based pulmonary rehabilitation program, or the traditional centre-based pulmonary rehabilitation program.', 'armGroupLabels': ['Intervention']}
- {'type': 'BEHAVIORAL', 'name': 'Centre-based pulmonary rehabilitation', 'description': 'Participants will be offered a traditional centre-based pulmonary rehabilitation program', 'armGroupLabels': ['Control']}

Primary Outcomes:
- {'measure': 'All cause, non-elective hospitalisation', 'description': 'The number of participants hospitalised at least once will be compared between groups', 'timeFrame': '12 months after completing pulmonary rehabilitation'}

Please estimate the sample size based on the assumption: 
The study is designed to detect this difference with 80% power and a two-sided 0.05 significance level. The completion rate is anticipated to be 80% in the intervention group. An intracluster correlation coefficient of 0.01 and a 10% loss to follow-up are assumed.
Sample size
        The primary outcome is unplanned hospitalisation (inpatient admissions) in the 12 months following pulmonary rehabilitation. In our published Phase II trial,23 57% of the centre-based group were free from hospitalisation at 12 months, whereas 78% of rehabilitation completers were free from hospitalisation (regardless of group). Completion was 91% for HomeBase, and 49% for centre based.23 The novel aspect of the current study is that intervention participants will be offered a choice of models. Based on our experience recruiting for HomeBase, we expect that 75% of individuals may select a home programme of whom 91% will complete, and 25% will select centre-based of whom 49% will complete. We thus anticipate a completion rate of 80% in the intervention (choice) group.
        At 80% completion, our data indicate that 72% of the intervention group would remain free from admission at 12 months, compared with the observed rate of 57% in centre-based (control) participants.23 We thus expect 15% reduction in hospitalisations in the intervention group (choice of home-based or centre-based rehabilitation) compared with control (centre-based rehabilitation only). To detect a difference in remaining free from hospitalisation between intervention and control groups of 15% (72% vs 57%) with 80% power and a two-sided 0.05 significance level, 312 participants (156 in each group) are required. Adjusting for clustering by programme (intracluster correlation coefficient of 0.01, based on our published two-site trial and 35 participants per cluster), the total required sample is 418. Our previous study had 10% loss to follow-up, so to allow for this we will recruit a total of 490 participants from 14 pulmonary rehabilitation programmes.