Patterns and Sociodemographic Correlates of Substance Use Among Psychiatric Outpatients at a Tertiary Hospital in Tshwane, South Africa: A Cross-Sectional Study

Abstract

Substance use is a major global public health challenge and is closely associated with psychiatric illness. Patterns of use are shaped by sociodemographic and cultural factors, with men, younger individuals, and those with lower education at greater risk. Among psychiatric patients, substance use complicates treatment and worsens outcomes. This study aimed to (i) estimate the prevalence and patterns of substance use, (ii) examine sociodemographic factors associated with substance use, and (iii) explore associations between specific substances and psychiatric diagnoses among psychiatric outpatients at a tertiary hospital in Tshwane, South Africa. A hospital-based cross-sectional survey was conducted among 405 psychiatric outpatients. Substance use was assessed using the WHO Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST v3.1), and sociodemographic data were collected using a questionnaire. Descriptive statistics, Pearson Chi-square tests, logistic regression, and multinomial logistic regression were applied to examine associations. Participants had a mean age of 38.4 years; most were Black (98.5%), male (52.4%), and single (85.4%). Schizophrenia was the most common diagnosis (32.6%). Lifetime prevalence of substance use was high (70.1%), with alcohol (60.5%), tobacco (49.9%), and cannabis (26.4%) most frequently reported. Logistic regression showed higher odds of substance use among males (OR=1.96, 95% CI: 1.25–3.09), single individuals (OR=2.24, 95% CI: 1.21–4.16), and those with a family history of substance use (OR=1.98, 95% CI: 1.27–3.09). Multinomial regression revealed significant associations between tobacco use and schizophrenia (RRR=2.01, 95% CI: 1.05–3.81), and cannabis use and psychosis (RRR=7.04, 95% CI: 2.95–16.80). Substance use is strongly linked to psychotic disorders, particularly schizophrenia and psychosis, and is further shaped by sociodemographic vulnerabilities such as male sex, single marital status, and family history of substance use. These findings underscore the need for integrated mental health and substance use interventions in South Africa and point to the importance of nationally representative studies to clarify causal pathways and inform policy. Substance use is highly prevalent among psychiatric outpatients and is significantly associated with psychotic disorders. Addressing these challenges requires integrated care approaches that combine psychiatric and substance use services, alongside evidence-informed policies to reduce the burden of comorbidity and improve long-term outcomes.