BACKGROUND: Major depressive disorder (MDD) is common and associated with high social and economic burden. Knowledge of characteristics of hospitalized adults with MDD can help identify clinical treatment and prevention targets.

METHODS: The multicenter "Patient Characteristics, Validity of Clinical Diagnoses and Outcomes Associated with Suicidality in Inpatients with Symptoms of Depression" (OASIS-D) study assessed characteristics of patients aged 18-75 years hospitalized between October 2020 and December 2024, who were admitted to a psychiatric inpatient unit for MDD at eight German centers. Baseline illness-, treatment-, and suicidality-related characteristics of the overall sample are reported.

RESULTS: Among 3795 patients (median age = 42.0, interquartile range [IQR] = 27.5-57.0 years; females = 53.9%) with MDD (severe episode = 75.3%, psychotic features = 7.9%; first episode = 34.9%; treatment-resistant depression [TRD] = 18.2%). Psychiatric comorbidities of MDD were present in 46.2% and included substance use disorder (18.9%), personality disorders (8.4%), stress/adjustment disorders (7.6%), and phobic/other anxiety disorders (6.6%). In 42.5%, the admission was prompted by a psychiatric emergency, primarily due to suicidality (35.0%), followed by stupor/refusal/intoxication/acute agitation (0.9%-1.5%), or danger to others/delirium (0.1%-0.3%). Overall, 72.0% of patients had active or passive suicidal thoughts, and 11.5% had attempted suicide within 2 weeks prior to admission. Furthermore, 83.9% had lifetime suicidal thoughts, and 36.0% had lifetime suicide attempts. Altogether, 76.8% had received outpatient psychiatric care within their lifetime (62.3% within 6 months), and 57.8% of patients had lifetime inpatient treatment for MDD. At admission, 71.6% of patients were prescribed psychiatric medications: antidepressants = 59.8%; antipsychotic = 25.1%, anxiolytics/hypnotics = 11.8%, and mood stabilizers = 8.6%. Additionally, 4.0% had previously received electroconvulsive therapy (ECT). The median hospitalization duration was 31.0 (IQR = 13.0, 57.0) days.

CONCLUSION: Almost half of admissions in adults with MDD were considered emergencies, with 90% being related to suicidality, and only <60% received antidepressants at admission. These data underscore the need for early identification and treatment of adults with MDD, especially those with suicidality. Outcomes of this population required further study. Trial Registration: ClinicalTrials.gov identifier: NCT04404309.