Prevalence and factors associated with illicit substance use among persons with Schizophrenia at a Tertiary Referral Hospital in Zambia

Schizophrenia frequently involves comorbid substance use, exacerbating symptoms and reducing treatment efficacy yet no prior studies have examined this comorbidity locally. This study determined the prevalence and factors associated with illicit substance use among adults with schizophrenia at the Livingstone University Teaching Hospital (LUTH). A hospital-based single center cross-sectional study was conducted at LUTH from January to June 2023. A sample of 303 adults with schizophrenia were recruited via systematic random sampling. Data were collected from existing medical records which included documentation from structured interviews with validated tools (Alcohol, Smoking, and Substance Involvement Screening Test [ASSIST], Positive and Negative Syndrome Scale [PANSS]) conducted as part of routine clinical care. Sociodemographic, clinical, and substance use variables were analyzed using chi-square tests and multivariate logistic regression to identify factors associated with illicit substance use. The prevalence of illicit substance use was 31.1% (94/303). Alcohol use (AOR = 6.08, 95% CI: 3.14-11.78, p < 0.0001) and tobacco smoking (AOR = 4.80, 95% CI: 2.44-9.46, p < 0.0001) were strongly associated with illicit substance use. Factors associated with lower odds of illicit substance use included female sex (AOR = 0.27, 95% CI: 0.12-0.60, p = 0.001), marriage (AOR = 0.39, 95% CI: 0.19-0.79, p = 0.008), having both parents deceased (AOR = 0.29, 95% CI: 0.11-0.75, p = 0.011), and higher education (AOR = 0.44, 95% CI: 0.24-0.81, p = 0.009). Increased hospitalizations were associated with illicit substance use (AOR = 1.29, 95% CI: 1.01-1.65, p = 0.038). Integrated screening, gender-specific interventions, and socioeconomic support related to illicit substance use are urgently needed in Zambia's resource-constrained setting.