Here is the design of a clinical trial:

Official Title: Effectiveness of Tobacco Cessation Interventions for Different Groups of Users in Sweden: a National Prospective Cohort Study

Included conditions:
- Tobacco Use
- Smoking
- Cigarette Use, Electronic

Study Armgroups:
- {'label': 'Exposed', 'description': 'Several studies will be performed based on this cohort. I each study the exposed group will be a group of tobacco users evaluatedin the relevant study. This could be a vulnarable group tobacco users such as: users without a job, with short or no education, without permanent housing, diagnosed with mental illness, diagnosed with chronic obstructive pulmonary disease (COPD), undergoing surgery, adolescents, elderly, migrants, or pregnant women.', 'interventionNames': ['Behavioral: Tobacco cessation intervention']}
- {'label': 'Unexposed', 'description': 'In each study the unexposed group will consist of tobacco user from the study cohort without the condition examined in the relevant study.', 'interventionNames': ['Behavioral: Tobacco cessation intervention']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Tobacco cessation intervention', 'description': 'Already implemented in-person (including online meetings) tobacco cessation interventions in Sweden', 'armGroupLabels': ['Exposed', 'Unexposed']}

Primary Outcomes:
- {'measure': '% of patients that are continuously smokefree', 'description': 'Self-reported smoking status, questionnaire completed by telephone interview', 'timeFrame': '6 months'}

Please estimate the sample size based on the assumption: 
A two-sided test, a 5% level of significance, a power of 80%, and an expectation of high acceptance and follow-up rates among patients.
Sample size
          The sample size was calculated for the dichotomous main outcome (successful quitting (yes/no) after 6 months) and based on the following assumptions: a two-sided test, a 5% level of significance, a power of 80%, an estimated effect in the control group of 35%, and a minimum relevant difference of 5â10âpercentage points.
          The online calculator âInference for Proportions: Comparing Two Independent Samplesâ (www.stat.ubc.ca/%7Erollin/stats/ssize/) was used to estimate the necessary sample size of each group. Based on a minimal relevant difference on 10% and 5% each group should include at least 329 and 1377 tobacco users, respectively. As the study groups in this study are not equal-sized, the sample size gives the estimated size of the smallest group (the vulnerable group in question).
          We expect to include 8000 patients. Based on the overall existing interest from the tobacco cessation counsellors, at least 200 of them are each expected to collect data from at least 20âpatients/year. The large majority of potential patients are expected to accept inclusion and follow-up.31 To be able to manifest a difference in effect size of 10%, 4% for the included patients would have to belong to each of the given risk factors (vulnerable groups). To show a difference of 5%, this would be the case for 17% of the included patients.