Quantifying Structural Disadvantage in HIV Prevention: Development and Validation of the HIV-Specific Social and Structural Determinants Index in the United States

Structural inequities significantly shape disparities across the HIV care continuum, yet few validated tools exist to quantify HIV-specific structural vulnerability at the population level in the United States. This study introduces and validates the HIV-Specific Social and Structural Determinants of Health Index (HIV-SSDI), a multi-dimensional, state-level index designed to capture structural disadvantage relevant to HIV prevention and care. Using publicly available state-level index (2008-2023) spanning nine structural domains, we developed the HIV-SSDI through exploratory factor analysis with three extraction methods: principal component analysis, maximum likelihood, and minimum residual. We constructed HIV-SSDI scores based on normalized factor loadings and evaluated their associations with HIV care continuum outcomes, using cross-sectional and longitudinal linear regression models. Three consistent latent factors emerged across methods: (1) socioeconomic and health care disadvantage, (2) HIV service infrastructure and urban density, and (3) structural/legal context. Higher HIV-SSDI scores were significantly associated with HIV prevalence, mortality, preexposure prophylaxis (PrEP) use, and testing rates but not with linkage to care or viral suppression. Longitudinally, the strength of association between SSDI and diagnosis rates declined between 2008 and 2022, while SSDI associations with PrEP use and PrEP-to-Need-Ratio increased sharply from 2012 to 2023. These trends were robust across factor extraction methods and model specifications. The HIV-SSDI is a validated, multi-dimensional metric that captures structural disadvantage relevant to HIV vulnerability and prevention. Its growing association with prevention outcomes over time supports its utility as a policy-relevant tool for identifying high-need states, guiding equitable resource allocation, and monitoring progress toward HIV-related health equity.