Severe mental illnesses (SMIs), such as major depression, schizophrenia, and bipolar disorder, carry a significant prevalence among patients admitted to the intensive care unit (ICU), estimated at an average of 19%. Evidence indicates that ICU hospitalization is associated with a poorer prognosis regarding mental health and morbi-mortality compared to hospitalization in conventional wards.

Despite this recognized vulnerability, available data remain limited and are often derived from retrospective studies with conflicting results. Some studies have shown that SMIs impact neither critical care nor long-term mortality. Conversely, other research has reported higher hospital mortality, an increase in complications (such as mechanical ventilation and prolonged length of stay), and unfavorable functional outcomes. Regarding specific conditions like septic shock, unexpected findings have been observed, with certain SMIs appearing to be associated with reduced 90-day mortality compared to a matched control population.

Patients with SMIs thus represent a vulnerable population whose management in the ICU setting may pose specific challenges. This prospective, multicenter study aims to evaluate mortality and identify predictive factors of mortality among patients with SMIs managed in French ICUs.

Inclusion Criteria:

• Age ≥ 18 years.
• Admission to a participating ICU.
• Unscheduled ICU admission for medical management, urgent post-operative care, or due to a complication of elective surgery.
• Pre-existing diagnosis of a severe mental illness prior to ICU admission, according to DSM-5 criteria: schizophrenia, schizoaffective disorder, severe major depressive episode, chronic depressive disorder, recurrent depressive disorder, or bipolar disorders.
• Current chronic treatment with psychotropic medication at the time of enrollment (antidepressants, neuroleptics, other antipsychotics, lithium, or antiepileptic drugs used as mood stabilizers).
• Non-opposition to participate from the patient; if the patient is unable to receive information, non-opposition from a relative/trusted person; for patients under guardianship or curatorship, non-opposition from both the legal guardian and the patient.

Exclusion Criteria:

• Scheduled ICU admission following elective surgery.
• Prior enrollment in the REPSYRE study.
• Inability to speak or understand French.
• Homeless patients or individuals deprived of liberty.
• Any other condition or reason that, in the investigator's judgment, might interfere with the evaluation of the study objectives.

Patients with severe mental illnesses admitted to the ICU for unscheduled medical management, urgent post-operative care, or due to a complication of elective surgery.