SUMMARY
Background: Substance abuse and mental disorder comorbidity is high among patients admitted to acute psychiatric wards. The aim of the study was to identify this co-occurrence as a reason for involuntary admission and if specific substance use-related diagnoses were associated with such admissions.Methods: The study was a part of a multicentre, cross-sectional national study carried out during 2005-2006 within a research network of acute mental health services. Seventy-five percent of Norwegian hospitals providing acute in-patient treatment participated. Substance use was measured using the Clinician Rating Scale and the ICD-10 diagnoses F10-19. Diagnostic assessments were performed by the clinicians during hospital stay.Results: Overall, 33.2% (n=1,187) of the total patient population (3,506) were abusing alcohol or drugs prior to admission according to the Clinician Rating Scale. No difference in the overall prevalence of substance abuserelated diagnoses between the two groups was found. Overall, 310 (26%) of the admissions, 216 voluntarily and 94 involuntarily admitted patients received a double diagnosis. Frequent comorbid combinations among voluntarily admitted patients were; a combination of alcohol and either mood disorder (40%) or multiple mental disorders (29%). Among involuntarily admitted patients, a combination of poly drug use and schizophrenia was most frequent (47%). Substance abusing patients diagnosed with mental and behavioral disorders due to the use of psychoactive stimulant substances had a significantly higher risk of involuntary hospitalization (OR 2.3).Conclusion: Nearly one third of substance abusing patients are involuntarily admitted to mental hospitals, in particular stimulant drug use was associated with involuntarily admissions.