Prevalence, patterns, associated factors and severity of substance use among psychotic patients in southern Thailand

•We aims to investigate the prevalence of substance use among psychotic patients.•We found that tobacco was the most common substance used.•Emotional and behavioural symptoms associated with higher substance use risk.

Co-occurring substance use in psychotic patients causes many subsequences including increased illness severity, decreased medication compliance, higher relapse rates, more hospitalizations, and legal problems. We aim to investigate the prevalence, patterns, associated factors and severity of substance use risk among psychotic patients in southern Thailand. Psychotic out-patients were screened with the Alcohol, Smoking, Substance Involvement Screening Test (ASSIST) for their history of substance use in the past three months and categorized as None-to-Low Risk (NLR) or Moderate-to-High Risk (MHR) levels. Multivariate logistic regression was used to examine the associated factors of substance use risk-level. The associations between substance use risk-level and emotional and behavioural symptoms, functional status and family functional status were examined using multivariate linear regression analysis. Of 663 participants screened, 322 (48.6%) used at least one substance in the past three months. Tobacco was the most common substance used (47.2%). The factors associated with a higher risk of any substance use were male gender, young age group, low level of education, being employed and being diagnosed with schizophrenia. A higher number of emotional and behavioural symptoms was significantly associated with higher substance use risk-level. In conclusion, the prevalence of substance use in psychotic patients was high and associated with their emotional and behavioural symptoms. Recommendations for implementation of screening and early intervention programs of substance-related problems in psychotic patients are important for preventing unwanted outcomes.