Here is the design of a clinical trial:

Official Title: Effectiveness and Safety of a Flexible Family Visitation Model for Delirium Prevention in Adult Intensive Care Units: a Cluster-randomized, Crossover Trial

Included conditions:
- Delirium

Study Armgroups:
- {'label': 'Flexible Family Visitation Model (FFVM)', 'type': 'ACTIVE_COMPARATOR', 'description': 'In the FFVM, two or fewer family members will be allowed to visit the patient for up to 12 consecutive hours each day. In addition to family visitation, patients will be allowed to receive social visits in specific time intervals (according local ICU regulation). To have access to the FFVM, family members of ICU patients will have to attend a structured meeting at ICU in which they will receive orientations about the ICU environment, common ICU treatments, rehabilitation and basic infection control practices, multidisciplinary work at ICU and palliative treatment. Social visitors will not be required to attend the structured meeting.', 'interventionNames': ['Other: Flexible Family Visitation Model (FFVM)']}
- {'label': 'Restrictive Family Visitation Model (RFVM)', 'type': 'ACTIVE_COMPARATOR', 'description': 'In the RFVM, patients will be allowed to receive restricted visits according routine ICU practices, but respecting the maximum limit of 4.5 hours of visitation per day. Visitors will not be required to attend the structured meeting. The length of ICU visits will be similar to those of social visits in the FFVM.', 'interventionNames': ['Other: Restrictive Family Visitation Model (RFVM)']}

Interventions:
- {'type': 'OTHER', 'name': 'Flexible Family Visitation Model (FFVM)', 'description': 'Visitation to ICU patients allowed during the period of 12 consecutive hours per day.', 'armGroupLabels': ['Flexible Family Visitation Model (FFVM)']}
- {'type': 'OTHER', 'name': 'Restrictive Family Visitation Model (RFVM)', 'description': 'Visitation to ICU patients allowed during intermittent periods according local ICU regulation.', 'armGroupLabels': ['Restrictive Family Visitation Model (RFVM)']}

Primary Outcomes:
- {'measure': 'Incidence of Delirium among ICU patients', 'description': 'Incidence of delirium will be verified by trained intensive care professionals with the confusion assessment method for the ICU 2 times per day.', 'timeFrame': 'During ICU stay (from enrollment until ICU discharge, or death or a maximum of 30 days of follow-up)'}

Please estimate the sample size based on the assumption: 
80% power, two-tailed 0.05 alpha, intraclass correlation coefficient (ICC) of 0.05 for subjects in the same cluster/time period and 0.01 for subjects in the same cluster/different time periods.
Sample size and sampling
        A minimum of 33 ICUs with recruitment rate of 50 patients per ICU (25 patients per study phase) will be needed (total of 1650 patients) to detect an absolute differenceÂ >6.0%âin the cumulative incidence of delirium between the two study arms (considering an outcome incidence rate of 20.5% in the RFVM), with 80% power, and two-tailed 0.05 alfa. Two levels of intraclass correlation coefficient (ICC) were considered to calculate the sample size: 0.05 for subjects in the same cluster/time period and 0.01 for subjects in the same cluster/different time periods. Estimates of sample size for the primary outcome were made on the basis of the cumulative incidence of delirium found in a single centre before-and-after study that evaluated the effect of different policies of family visitation on the incidence of delirium.12 In order to compensate for potential ICU and patient losses, the present study plans to recruit 40 ICUs.