Exploration of the comorbidity of alcohol use disorders and mental health disorders among inpatients presenting to all hospitals in New South Wales, Australia.

Alcohol is one of the most commonly used legal psychoactive substances, and its use often coexists with mental health disorders. This study explores the relationships between alcohol use and some common mental health disorders. Admissions to all New South Wales (NSW) hospitals were analyzed. The data were extracted from the NSW Department of Health Inpatient Statistics Data Collection for the period 1 July 2006 to 30 June 2007. Readmissions within 28 days were excluded. Data extraction and analyses were performed by using the SAS program. Chi-square tests and odds ratio were used to measure the association. Of the 1.8 million admissions, associations between alcohol use disorders and mental health disorders were strong (odds ratio 7.8 to 10.7, P < .001). A 33.8% of patients who used alcohol had at least 1 identifiable mental disorder. Higher comorbidity rates were observed for females (39.6%) and for those aged between 30 and 49 years. The most common mental disorders were anxiety disorders, bipolar affective disorders, major depressive disorders, personality disorders, schizophrenia, and severe stress disorders. Comorbidity with one of these mental disorders ranged from 1% to 17.6%, with significant associations (odds ratio 5.6 to 14.1). The average length of stay (ALOS) for alcohol use disorders were 6.4 days and the ALOS for the most common mental health admissions was 11.2 days. This study provides detailed information about the association between alcohol use and mental health disorders and extends our understanding of comorbidity presentations in inpatient admissions.