First Episode Psychosis (FEP) includes perceptual distortions, delusions and cognitive impairment with severe consequences, such as suicidal behaviour. It affects 3% of the population, mainly adolescents and young adults, the majority of with progress to a psychotic disorder.

The early stages of psychotic disorders, from the first full blown symptoms to the next two to five years, represent an opportunity to targeted care and prevention. Indeed, it is a critical period with a worsened clinical prognostic when intervention is delayed, increasing the duration of untreated psychosis (DUP). Also, it is a key period to reduce mortality, as it is characterized by elevated risks of suicide and low physical health outcomes. Besides the symptomatic components, this period is also critical for self-building on educational, professional and emotional levels.

Early intervention programmes involve multi-disciplinary teams, including a care coordination function, embodied by a "case manager". His missions include assessing the patient's needs, developing a care plan to meet the latter, organising access to the different components of the care plan, monitoring and evaluating care, and providing clinical follow-up.

Engagement in the care process is fragile in psychotic disorders, particularly in the context of first episode psychosis with a high risk of care disengagement, often associated with a relapse. It is therefore essential that case-managers involved in FEP services have access to tools designed according to the patient needs and not solely to symptoms, in a "recovery oriented" approach, to foster the feeling of commitment of patients in their care process.

The use of mobile applications for smartphones represents an interesting perspective to improve the engagement of patients with FEP in care. However, the use of an application focused on recovery is feasible and acceptable in patients with first episode psychosis enrolled in a specialised outpatient department (FEP-type service) and allows improvement on clinical criteria, such as psychotic symptoms or mood.

User-centred design methods including identification of users and an inventory of their needs, prototyping with rapid iterations, is a simplification of the procedure and exploitation of existing constraints to increase the rate of use. Moreover, it has recently been shown that such a methodology is feasible in populations with a first episode of psychosis.

Our hypothesis is that the use of a mobile case-management application for planning and monitoring individualised care objectives, co-designed with patients, their careers, and health professionals, improves the functioning of patients managed for a first psychotic episode, compared to usual case management practices.

The originality of our project is built up on two pillars :

• the use of a a mobile monitoring application, which will be used jointly by patients and case-managers,
• the methodological innovation also lies in the collaborative and patient-centred design of the application The originality of our project concerns on the one hand the intervention, an application mobile follow-up, which will be used jointly by patients and case managers. The innovative character also lies at the methodological level in the collaborative and patient-centered design of the application ('user-centered design' approach).

Psychosis and early intervention First Episode Psychosis (FEP) includes perceptual distortions, delusions and cognitive impairment with severe consequences, such as suicidal behaviour. It affects 3% of the population, mainly adolescents and young adults, the majority of wish progress to a psychotic disorder.

From the first full blown symptoms to the next two to five years, the early stages of psychotic disorders represent an opportunity to targeted care and prevention. Indeed, it is a critical period with a worsened clinical prognostic when intervention is delayed, increasing the duration of untreated psychosis (DUP). Also, it Is a key period to reduce mortality, as it is characterized by elevated risks of suicide and low physical health outcomes. Besides the symptomatic components, this period is also critical for self-building on educational, professional and emotional levels.

A pejorative evolution can be avoided by the establishment of "early intervention in psychosis" (EIP), constituted by a set of integrated supports that allow to reduce the symptoms of the disease, promote recovery, foster better social and professional functioning. Moreover, it has recently been shown that EIP reduces general mortality including by suicide in the population monitored. In addition, medico-economic benefits of early intervention have been demonstrated in terms of direct and indirect costs. Thus, this intervention model is currently considered as the reference care in early intervention.

Case management: a strategy to promote recovery in early psychosis Early intervention programmes involve multi-disciplinary teams, including a care coordination function embodied by a "case manager". His missions include assessing the patient's needs, developing a care plan to meet the latter, organising access to the different components of the care plan, monitoring and evaluating care, and providing clinical follow-up. Those missions are broken down into several actions, the content is adapted to the duration of care according to the severity of the disorder and the level of remission.

Case management require essential qualities/ skills such as: accessibility, flexibility, optimism and competence. This model of intervention is effective for patients with FEP and is now considered as a "standard" of care for this population Psychosis and engagement in healthcare: a critical situation In psychotic disorders, the engagement in the care process is fragile, particularly in the context of first episode psychosis with a high risk of care disengagement, often associated with a relapse. Between 20 and 40% of patients with FEP disengage with care despite significant therapeutic needs. The relapse rate one year after stopping treatment ranges from 28% ( to 67% after a first episode of psychosis. Due to the complexity of factors involved in the engagement, it remains endlessly threatened despite better engagement rates in dedicated FEP services compared to "traditional/usual" care, of which the most important is the perception that the service is not adapted to their needs. It is therefore essential that case-managers involved in FEP services have access to tools designed according to the patient needs and not solely to symptoms, in a recovery-oriented approach, to foster the feeling of commitment of patients in their care process.

Mobile applications in mental health: a promising way to promote engagement in FEP services The use of mobile applications for smartphones represents an interesting perspective to improve the engagement of patients with FEP in care. Mobile mental health applications offer many possibilities: an appointment management, an information on the illness, a monitoring of symptoms, a deployment of psychotherapeutic techniques, etc… Mobile applications appear now as promising tools not only for better engagement in care, but also for better self-management capabilities and better coordination of resources. Recent data show an increase in the rate of smartphone equipment in the population of patients with psychosis (over 80%). Qualitative studies in this population show that this type of tools is in great demand, in particular to promote the bound between the patient and services and strengthen the self-management capacities.

Many of the recently implemented applications are aimed for in-patients with short evaluation periods, which does not allow longer term usage data. However, the use of an application focused on recovery is feasible and acceptable in patients with first episode psychosis enrolled in a specialised outpatient department FEP-type service) and allows improvement on clinical criteria, such as psychotic symptoms or mood.

Despite the fact that some applications specifically designed for FEP patients exist and have shown promising results, none have been developed in French and evaluated in French healthcare system. Moreover, anchoring the design of the application in recovery theory would make it possible to better align the actions resulting from the use of the application with the patient's needs.

User-centred design: a method suitable to build "recovery-oriented" tools User-centred design methods, initially developed for human-computer interactions are generally broken down into several phases, including identification of users and an inventory of their needs, prototyping with rapid iterations (i.e. a trial-and-error type strategy allowing rapid feedback from users), simplification of the procedure and exploitation of existing constraints to increase the rate of use. These approaches are particularly developed in the field of mobile application design because they make it possible to create a product that is closer to the concerns of the target person and is so particularly suitable for a "recovery-oriented" approach. Moreover, it has recently been shown that such a methodology is feasible in populations with a first episode of psychosis.

Research hypothesis Our hypothesis is that the use of a mobile case-management application for planning and monitoring individualised care objectives, co-designed with patients, their careers, and health professionals, improves the functioning of patients managed for a first psychotic episode, compared to usual case management practices

Inclusion Criteria:

• Men and women aged between 18 and 30 years old enrolled in a specialised FEP service for a first psychotic episode, defined as follows:

Presence of daily psychotic symptoms for more than a week that have been characterised at the clinical examination by a psychiatrist, Initiation of antipsychotic treatment for less than 6 months, A diagnosis of schizophrenia, schizoaffective disorder, schizophreniform disorder or brief psychotic disorder established according to DSM-5 criteria.

• Mastery of the French language (read and spoken)
• Owning a smartphone
• Adult patients who have given written consent

Exclusion Criteria:

• Patients in psychiatric intensive care units because of severe agitation/disorganisation.
• Patients under guardianship

Randomisation 1/1 comparing an early intervention program "standard "and an" extended "program within a specialized team will be carried out by IWRS (ENNOV Clinical solution) using the swapped block method. A stratification will be carried out on the case-manager. There is no blinding for the patient or the case-manager. Nevertheless, the evaluation of the comparative outcomes between the 2 groups will be carried out by a psychiatrist who is not involved in the patient's follow-up and who will be blinded to the patient's group.