comorbidity and pattern of substance use in hospitalized psychiatric patients

background substance use in patients with psychiatric disorder is an every-day seen. detection of this comorbidity can significantly affect the treatment of these disorders, as well as substance use. objectives this study has been conducted to determine the prevalence and pattern of substance use in hospitalized psychiatric patients. patients and methods in this cross-sectional study, 210 hospitalized psychiatric patients were selected by simple randomization from all records of hospitalized patients. the instrument of gathering data was a demographic checklist including age, gender, marital status, education, type of disorder and substance abuse and duration of psychiatric disorder. data were analyzed by spss version 16 using fisher exact and chi square tests. results the mean age of patients was 37.9 years. most of the patients were male, married and unemployed. the prevalence of substance use was 36.7%. the most prevalent pattern of substance use was opium, opioid, methamphetamines and other substances (poly substance). the prevalence of substance use in patients with mood disorders was more than the other disorders and the most prevalent substance use in these patients was opium and opioid. poly substance use was the most prevalent pattern of use (80 %) in psychotic and mood disorders due to substance. significant difference was seen between genders, marital status, occupation, duration of illness and frequency of substance use (p < 0.05 ), however no significant difference was seen between educational levels, age and substance use. conclusions the patients with mood disorders had the highest comorbidity with substance use and concurrent use of poly substance was the most prevalent pattern of use in these patients. therefore, successful treatment of psychiatric disorders and substance use needs multimodal and more serious interventions. regarding to the pattern of poly substance use in these patients, careful screening should be performed at admission.