Socio-economic indicators, housing characteristics, site of residence, and substance use as household-level risk factors in GRT-INSPIRED communities.

Introduction: Substance use remains a major public health concern in South Africa and disproportionately affects urban communities experiencing socio-economic disadvantage, poor housing conditions, and spatial inequality. While existing research has largely focused on individual-level substance use, less is known about how household socio-economic characteristics, housing conditions, and place of residence shape household-level substance use in urban settings. This study examined the associations between socio-economic indicators, housing characteristics, site of residence, and household substance use in selected urban communities in Gauteng Province, South Africa. Methods: A cross-sectional household-level analysis was conducted using secondary data from the GRT-INSPIRED Health and Demographic Surveillance System (HDSS). The study included 46,113 households from three urban sites: Hillbrow, Atteridgeville, and Melusi. Household substance use was defined as the presence of any reported substance used within the household. Socio-economic variables included employment status, income classification, and government grant receipt, while housing variables captured building type, housing disrepair, and the presence of multiple structures. Descriptive analyses were followed by bivariable and multivariable logistic regression to estimate adjusted odds ratios (AORs) and 95% confidence intervals (CIs). Results and discussion: Alcohol was the most commonly reported substance among households with substance use, reported by 10,453 households (77.1%; 95% CI: 76.4-77.8). In multivariable analysis, households reporting housing disrepair had substantially higher odds of substance use (AOR = 4.43; 95% CI: 3.24-6.05). Residence in Melusi was strongly associated with household substance use compared with Hillbrow (AOR = 4.04; 95% CI: 3.44-4.75). Low-income households had lower odds of substance use (AOR = 0.71; 95% CI: 0.61-0.83), while grant receipt was associated with higher odds (AOR = 1.29; 95% CI: 1.05-1.58). Household substance use in urban Gauteng is strongly shaped by housing quality and spatial context, highlighting the importance of structural and place-based determinants. Integrated urban health interventions addressing housing conditions and neighborhood vulnerabilities are critical for reducing substance-related harm.