Housing-Based Socioeconomic Status at Birth and Infant Mortality in a Population-Based Cohort.

OBJECTIVE: Socioeconomic status (SES) impacts infant mortality risk, yet measuring individual-level SES in large health datasets remains challenging. We evaluated the association between individual-level SES, measured via the HOUsing-based SocioEconomic Status (HOUSES) index, and infant mortality within a population-based cohort. METHODS: This retrospective cohort study used the Rochester Epidemiology Project (REP) medical records-linkage system to evaluate live births from 2010 to 2021. The primary exposure was individual-level SES at birth, quantified into quartiles (Q1=lowest SES, Q4=highest SES) using the HOUSES index, which is derived from real property tax assessor data. The primary outcome was infant mortality (death <365 days). Survival probabilities across HOUSES quartiles during the initial 365 days post-birth were evaluated using Kaplan-Meier curves and log-rank tests. Multivariable Cox proportional hazards models estimated adjusted hazard ratios (aHR) for infant mortality. RESULTS: Among 79,444 infants with HOUSES data, overall infant mortality was 0.42% (n=332). Kaplan-Meier analysis demonstrated significantly lower survival probability across lower HOUSES quartiles (log-rank p, 0.011). After adjusting for prematurity and congenital anomalies, infants in the lowest HOUSES quartile (Q1) experienced a significantly increased risk of mortality compared to those in the highest quartile (Q4; reference group) (aHR: 1.41; 95% CI: 1.03-1.92; p, 0.031). CONCLUSIONS: Lower housing-based SES at birth is independently associated with an increased risk of infant mortality. The HOUSES index represents an objective, scalable tool to identify at-risk families and address social drivers of health in clinical and epidemiological research.