Past-year substance use behaviors among university admission test-takers: insights from Bangladesh

University entrance test-takers are a vulnerable group of students transitioning from adolescence to youth, a peak time for adopting unhealthy behaviors. However, limited studies investigate substance use behaviors among this group. This study aimed to investigate the current (past 12 months) prevalence, associated risk factors, and geographic distribution of substance use behaviors, employing spatial analysis to identify regional disparities. A cross-sectional study was conducted utilizing convenience sampling in February 2024 among university entrance test-takers at Jahangirnagar University, Dhaka, Bangladesh (N = 1485). Participants provided information on socio-demographics, admission-related, depression (PHQ-9), anxiety (GAD-7), and substance use. Chi-square tests and logistic regression were employed to explore significant associations, with spatial analysis using ArcGIS to map substance use across districts. About 20.8% reported smoking, 10.1% reported drug use, and 9.9% reported alcohol consumption over the past 12 months. Males exhibited higher rates of smoking (23.1% vs. 17.6%) and alcohol consumption (10% vs. 9.7%), while females reported slightly higher rates of drug use (10.2% vs. 10%). Being female (AOR = 0.56; 95% CI: 0.40-0.79; p = 0.001), living in rural areas (AOR = 0.68; 95% CI: 0.49-0.94; p = 0.020), having a higher monthly family income (AOR = 1.72; 95% CI: 1.01-2.91; p = 0.042), a history of physical illness (AOR = 2.65; 95% CI: 1.87-3.76; p < 0.001), being a repeat test-taker (AOR = 1.49; 95% CI: 1.08-2.05; p = 0.014), and satisfaction with previous mock tests (AOR = 1.66; 95% CI: 1.20-2.28; p = 0.002) were significant risk factors for smoking. For drug use, belonging to a joint family (AOR = 1.71; 95% CI: 1.08-2.71; p = 0.021), having a history of physical illness (AOR = 2.57; 95% CI: 1.64-4.02; p < 0.001), and satisfaction with previous mock tests (AOR = 1.84; 95% CI: 1.20-2.83; p = 0.005) increased the risk. Additionally, a history of physical illness (AOR = 5.12; 95% CI: 3.27-8.02; p < 0.001) and satisfaction with previous mock tests (AOR = 1.78; 95% CI: 1.13-2.80; p = 0.013) were contributing factors to alcohol consumption. Spatial analyses indicated higher rates of substance use in border districts. The findings warrant targeted interventions, such as mental health support and substance use prevention programs, particularly in high-risk regions. By understanding the factors driving substance use, tailored strategies can be developed to reduce risk behaviors among university entrance test-takers, ultimately enhancing public health outcome in this vulnerable population.