Disposition of emergency department patients with psychiatric comorbidity: results from the 2004 National Hospital Ambulatory Medical Care Survey

BACKGROUND: Few emergency department (ED) studies have examined how psychiatric comorbidity relates to hospitalisation decisions. METHODS: We assessed the relationship of psychiatric comorbidity to hospitalisation decisions among ED patients in the 2004 National Hospital Ambulatory Medical Care Survey. RESULTS: Patients with psychiatric comorbidity were five times more likely to be hospitalised than patients with a single psychiatric diagnosis. The most frequent psychiatric comorbidities involved substance use disorders (SUDs). CONCLUSIONS: Psychiatric disorders are underdiagnosed among ED patients. We believe that this underdiagnosis may be partly responsible for the high hospitalisation rates of ED patients with SUDs.