It is an interventional research, single-blind, randomized, controlled, multicenter, which involves only minimal risks and constraints.

Patients who attend to the emergency department following a SA (Suicidal Attempt) represent a key group of patients with an extremely high risk of suicide in the short term.

A main problem in suicide prevention is that the increase of symptoms and suicidal risk occurs most often in the natural environment of patients, away from the system of care. Thus, the main goal in allowing real-time risk detection would facilitate immediate interventions, probably the best way to prevent a suicidal act. Additionally, the evolution of the suicidal crisis is very variable from one subject to another, in duration and symptoms, and often very brief. In contrast, the tools used to assess suicidal thoughts have so far been limited to intermittent assessments separated by weeks, months or years, which does not take into account the fact that suicidal thoughts can be highly variable over a few hours and that suicide attempts can occur in response to a rapid increase in thoughts over periods as short as the day. Mobile health (mHealth) interventions are the only that can respond to these fluctuations over time.

We have developed the first French app (emma) for EMA (Ecological Momentary Assessment) , customised EMI (Ecological Momentary Intervention) and prediction of SB (suicidal behaviour). It was designed by integrating evidence-based suicide prevention strategies and recommendations for the development of apps in the field of mental health. Emma helps to strengthen the patient's connection to his healthcare system and social network. This study led to the development and subsequent deployment of VigilanS. VigilanS is a multi-regional innovative care program for the prevention of suicide relapse, which has been implemented in several emergencies departments in France.

Our hypothesis is that emma offers an unprecedented opportunity to increase the efficiency of VigilanS, both for patients, by restoring their social connections, and for health professionals, in a simple, fast and efficient way. Thanks to emma, the patient will have daily support adapted to his condition (emotion management modules, safety plan, calls in case of emergency). Emma will fit easily into the daily practice of health professionals (little binding, little time consuming) and will complete the range of care organized by VigilanS.

The main objective is to evaluate over a 6-months follow-up the efficacy of a smartphone app (emma) in addition to the VigilanS program on the prevention of a suicidal event (suicide, SA, hospitalization or emergency department for suicidal ideation) compared to the VigilanS program only.

632 participants will be enrolled and randomized into 2 groups:

• Control group: 316 suicide attempters will benefit from the VigilanS program alone
• Interventional group: 316 suicide attempters will benefit from the emma app in addition to VigilanS

The duration of inclusions is 24 months. Each patient's participation period is 6 months and includes three visits (inclusion, at 3 and 6 months).

At each visit, a clinical assessment will be performed to characterise psychopathology and suicidal characteristics.

Inclusion Criteria:

• Subject aged 18 or over
• Subject benefiting from the VigilanS program (after an admission to an emergency ward following a suicide attempt)
• Subject with his own smartphone (iOS/Androïd)
• Subject able to understand the nature, purpose and methodology of the study
• Subject must be covered by public health insurance
• Signed informed consent form

Exclusion Criteria:

• Subject unable to read or/and write French
• Planned longer stay outside the region that prevents compliance with the visit plan
• Being protected by the law (tutorship or curatorship)
• Being deprived of liberty by administrative decision
• Being in a period of exclusion compared to another protocol
• Pregnant and breastfeeding women