Here is the design of a clinical trial:

Official Title: Evaluating the Efficacy of an Advanced Care Planning Program for Health Decisions in Patients With Advanced Heart Failure

Included conditions:
- Heart Failure

Study Armgroups:
- {'label': 'Control', 'type': 'NO_INTERVENTION', 'description': 'Patients will be followed in heart failure outpatients units according to the usual established protocol. In the first visit, patients from both control and intervention groups will complete the questionnaires with the help of researchers. After one year of follow-up, the questionnaires will be submitted again to all patients and three new questionnaires will be proposed.\n\nTreatment for heart failure will be the same in both groups.'}
- {'label': 'Intervention', 'type': 'EXPERIMENTAL', 'description': 'Patients will participate in the Advanced Care Planning Program. In the first visit, patients from both control and intervention groups will complete the questionnaires with the help of researchers. After one year of follow-up, the questionnaires will be submitted again to all patients and three new questionnaires will be proposed.\n\nTreatment for heart failure will be the same in both groups.', 'interventionNames': ['Behavioral: Advanced Care Planning program of health decisions']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Advanced Care Planning program of health decisions', 'description': 'Application of an Advanced Care Planning program program for decision-making in patients with advanced Heart Failure, in comparison to usual follow up and care.', 'armGroupLabels': ['Intervention']}

Primary Outcomes:
- {'measure': 'To evaluate the efficacy of an Advanced Care Planning program for decision-making in patients with advanced Heart Failure in comparison to usual follow up and care: questionnaire', 'description': "This objective will be evaluated by the PAM (Patient Activation Measure) test, which measures the participation and self-management of the patient in decision making. PAM measures the activation (participation and self-management) of the patient in decision-making. It evaluates the knowledge, skills and confidence of patients' self-management classifying patients in levels of self-management activation. Level 1: They do not feel responsible for their own health and care. (Score 47.0 or lower); Level 2: They may lack basic understanding about their condition, treatment options, and / or self-care. (47.1 to 55.1); Level 3: They know the basic facts of their illness and treatments. (55.2 to 67); Level 4: They have made most of the decisions, but they may have difficulties in maintaining behaviours over time or in stressful situations (67.1 or higher).", 'timeFrame': '24 months'}

Please estimate the sample size based on the assumption: 
Power of 80%, confidence level of 95%, 10% added for possible losses or errors in follow-up
Sample size calculation
        The sample size estimate has been made assuming a power of 80%, a confidence level of 95% in order to detect a standardized significant difference of at least 0.5. We consider 0.5 to be a clinically relevant difference based on the article by Norman et al. [20], being 128, the minimum sample size needed to detect this difference, 64 people in each group. A 10% sample size is added to compensate possible losses or errors in the follow-up, which represents 140 patients.