The most common presenting disorder was alcohol abuse (35.5%), followed by alcohol dependence (26.0%), cocaine (21.2%) and polysubstance use (17.4%) disorders. Patients with polysubstance use disorder were the most likely to also have been diagnosed with a psychiatric disorder (21.2%) in the ED. Patients with cocaine use disorders (14.3%) and alcohol dependence (14.1%) had similar rates of comorbid psychiatric disorders. Table 1 Characteristics of ED Users with Primary Substance Use Disorder Diagnoses KU-57788 Overall, the group of primary substance use disorder patients without Inhibitors,research,lifescience,medical a recorded psychiatric comorbidity had a mean of 2.5 visits (SD = 3.7)

over the study, while the patients with a psychiatric comorbidity had a mean of 5.2 visits (SD = 8.7; t-test for group mean difference significant at p < .001; Kruskal Wallis test significant at p= 0.02). Patients with psychiatric comorbidity had significantly more ED visits in every diagnostic category (data not shown) Inhibitors,research,lifescience,medical with similar mean values as noted above. Adjusted odds ratios (OR) for frequent use of the ED

are presented Inhibitors,research,lifescience,medical in Table ​Table2.2. In multiple logistic regression analyses predicting frequent use of the ED, substance use patients with a comorbid psychiatric disorder were consistently more likely to be frequent users (reference groups = patients with a substance use disorder but no psychiatric disorder; covariates controlled for included age, race, and gender). For example, with the substance use diagnoses collapsed together into one group, the range of ORs for the comorbid patients ranged from 3.0 (p < Inhibitors,research,lifescience,medical .001) at 4+ visits to OR = 5.6 (p < .0001) for 20+ visits. The most substantial association of psychiatric comorbidity to frequency of ED use occurred in the cocaine group, whose ORs ranged from 3.5 (p < .001) at 4+ visits to 9.3 (p < .001) at 20+ visits.

In terms of the relationships of the covariates to frequent ED use (data not shown), key findings were that males were significantly more likely to have more ED 4-Aminobutyrate aminotransferase visits in all categories of ED use in all substance Inhibitors,research,lifescience,medical use groups except for cocaine, African-Americans were more likely to have more visits in all ED use categories and in all groups, and persons younger than 30 years of age were less likely to have frequent visits than persons over 45 in all ED use categories and in all substance use groups except cocaine. Interactions tested between psychiatric comorbidity and age, race, and gender were not statistically significant. Table 2 Odds Ratios of Frequent Use of the ED for Substance Use Disorder Patients with Psychiatric Comorbidity vs. Those Without Discussion The data support the study’s hypothesis that a comorbid psychiatric disorder among patients presenting to an ED with primary substance use disorders is associated with increased ED use.