Hospitalizations for dual-diagnosis of drug-related and mental disorders, United States, 2003-2006

Dual-diagnosis is defined as a co-occurring status of drug-related and mental disorders. Such a diagnosis has been widely reported for its clinical implications in diagnostic and treatment methodologies and disease prognosis. However, little data are available on the impact of dual-diagnosis on the length of hospital stay and total hospital charges. Using the 2003 to 2006 Nationwide Inpatient Sample (NIS) data, we examined the differences between drug-related disorder patients with and without co-occurring mental disorders. We further assessed the relationships between dual-diagnostic status and the length of hospital stay and total hospital charges per discharge, using multivariate analysis of variance.

A total of 466,621 patients with a primary diagnosis of alcohol- or drug-related disorders were indentified between 2003 and 2006 in the NIS. Of these, 58,087 (12.4%) were also diagnosed with mental disorders. When weighted, it represents, nationwide, 70,708 dual-diagnosed patients per year. Patients who were male, non-white, of young age or admitted during the weekend had significantly lower odds of dual-diagnosis. Hospitals that were private, rural, or located in the Midwest or South had higher odds for dual-diagnosis. Compared to non-dual-diagnosis patients, dual-diagnosis patients had longer hospital stays, with an average of length of stay of 5.03 days vs. 4.88 days (p <.001), but lower hospital charges, with average hospital charges per discharge totaling $10,559 vs. $10,670 (p<0.001). Our study concludes that dual-diagnosis complicates inpatient treatment as reflected by longer hospital stay but does not result in an increase in hospital care cost.