The smoking rate among people with mental disorders is higher than in the general population. Greater exposure to the harmful effects of tobacco partly explains the major inequality in life expectancy observed among people with mental disorders who, depending on the disorder and the study, live 10 to 25 years less than the general population, a gap mainly due to the occurrence of cardiovascular and respiratory pathologies, notably bronchial cancers. However, tobacco reduction actions specifically targeting these people remain insufficiently developed, particularly in psychiatry where this addiction is often banalized and its treatment neglected.

The objective of this study is to evaluate an intervention ('Tabapsy') co-constructed with mental health services users, mental health professionals, and general practitioners and targeting adult patients followed in ambulatory psychiatry. The main objective is to evaluate the effectiveness of the intervention on short-term smoking cessation (cessation for at least 7 days) among regular smokers at 3 months. Secondary objectives include evaluation of its cost-effectiveness and implementation. To this end, a national cluster-randomized controlled study will be carried out, supplemented by qualitative interviews to study the implementation of the intervention.

The smoking rate among people with mental disorders is higher than in the general population. Greater exposure to the harmful effects of tobacco partly explains the major inequality in life expectancy observed among people with mental disorders who, depending on the disorder and the study, live 10 to 20 years less than the general population, a gap mainly due to the occurrence of cardiovascular and respiratory pathologies, notably bronchial cancers.

While studies found that people under psychiatric care are as motivated as others to stop smoking, the literature also shows that psychiatric care systems tolerate, underestimate and even encourage smoking among users, despite the fact that psychiatric care, whether at hospital or in an ambulatory setting, is conducive to changes in smoking behaviour and to the implementation of a smoking cessation approach, notably because of anti-smoking regulations in hospitals. In addition, withdrawal symptoms is stronger in this population and smoking cessation would therefore need to be adapted.

Against this backdrop, a smoking cessation intervention ('Tabapsy') was co-constructed with the various stakeholders (users with mental disorders, mental health professionals and general practitioners). Its aim is to encourage and support smoking cessation among people with mental disorders followed in ambulatory psychiatry by medical psychological centers (CMP). It consists of two parts: a campaign to promote smoking cessation within the CMP, and the setting up of an intervention to help people stop smoking. The latter comprises of:

1. A general information meeting, to encourage motivation to start smoking cessation;
2. An assessment workshop, to evaluate level of dependence using validated tests and establish a personalized cessation program based on the results obtained;
3. Five thematic workshops to support cessation, covering 1/ nicotine replacement treatments, electronic cigarettes and other drug treatments available for smoking cessation, 2/ emotional management, 3/ weight gain, 4/ physical activities, and 5/ manual occupations;
4. Peer support groups, based on the sharing of experiences, to encourage mutual aid and solidarity between people with mental disorders who are trying to quit smoking.

The intervention also relies on a facilitator specifically recruited to set up the intervention and run the various workshops in the CMP. It is complemented by a website that will contain all the resources and information presented during the meetings/workshops.

The primary objective of the study is to evaluate the effectiveness of the "Tabapsy" intervention on short-term smoking cessation (cessation for at least 7 days) at 3 months among regular smokers followed by adult psychiatric CMPs. Secondary objectives include assessing its cost-effectiveness and implementation.

A cluster-randomized controlled trial will be carried out to evaluate the intervention. The cluster is the "psychiatric sector", i.e., the public care entity responsible for organizing the mental health care of a population within a pre-specified geographical area (including hospital and ambulatory care) in France. A psychiatric sector may include one or multiple CMPs depending on the size of the population it serves. Psychiatric sectors will be randomized into one of two groups (intervention or usual practice).

It will be supplemented by a qualitative study to study the implementation of the intervention.

All regular smokers (at least one cigarette a day) who agree to participate will be asked to complete questionnaires on a WebApp at inclusion, and again at 3 and 6 months. Additional questionnaires will be available in the intervention group. Questions will focus on user characteristics, tobacco consumption, level of nicotine dependence, motivation to quit, use of cessation aids, level of mental and physical well-being, smoking-related knowledge and representations, and in the intervention group, participation in the intervention and satisfaction.

6,250 participants will be included over 12 months, in 22 participating sectors.

Inclusion Criteria:

• Regular smokers (at least one cigarette per day)
• Followed in psychiatric ambulatory care at one of the participating sectors' CMPs
• Adults (18 years or older)
• Covered by the statuary health insurance
• Who gave their informed consent to participate to the study

Exclusion Criteria:

• Users under guardianship or legal protection,
• Psychological state incompatible with completing the questionnaire,
• Persons with no command or understanding of the French language