Objective: Comorbidity of substance use disorders and other psychiatric disorders is common. However, data on the prevalence of substance use disorders in general psychiatric outpatient population is rather scarce.

Method: In order to investigate the prevalence of substance use disorders among the patients who admitted to the general psychiatric outpatient unit and followed with any psychiatric diagnosis, 734 consecutive adult patients were included in this study. Michigan Alcoholism Screening Test–AD was administered to these patients. Substance screening form and SCID-I dependence module were administered to 47 patients (6.4%) who had a MAST-AD score above 4. Later, SCID-II and the rest of SCID-I were administered to 33 patients (4.5%) who met any diagnostic criteria on this module.

Results: From these 734 patients, 33 (4.5%) had alcohol or substance use disorder: Five patients (0.7%) had alcohol dependence, 26 patients (3.5%) had alcohol abuse and 3 patients  (0.4%) had multiple substance dependence. There were 9 patients (1.2%) with cannabis abuse, 4 patients (0.5%) with ecstasy abuse, 1 patient (0.1%) with heroin abuse, 1 patient with (0.1%) biperiden abuse and 9 patients (1.2%) with benzodiazepin abuse. From this 33 patients, 7 (1.0%) patients were diagnosed with borderline personality disorder, 2 (0.3%) with antisocial personality disorder, 1 patient (0.1%) with paranoid personality disorder, 1 patient (0.1%) with narcissistic personality disorder, 2 patients (0.3%) with avoidant personality disorder, 1 patient (0.1%) with schizoid personality disorder and 1 patient (0.1%) with dependent personality disorder. With SCID-I, we found 5 (0.7%) major depressive disorder, 3 (0.4%) bipolar I, 1  (0.1%) distimic disorder, 2 (0.3%) paranoid schizophrenia, 1 (0.1%) delusional disorder, 3 (0.4%) generalized anxiety disorder, 3 (0.4%) panic disorder, 1 (0.1%) panic disorder with agoraphobia, 1 (0.1%) anxiety disorder not otherwise specified, 1 (0.1%) social phobia and 1  (0.1%) post-traumatic stress disorder.

Conclusion: These results suggest that substance use disorders are not prevalent among general psychiatric outpatients. Substance use disorders should be carefully assessed in patients with diagnoses of mood disorders, anxiety disorders or personality disorders.