Assessing the Impact of Housing on 30-Day ED Readmission: A Retrospective Analysis of Hospital Discharges in Maryland.

Despite being an important social determinant of health (SDOH), independent association of housing with emergency department (ED) utilization is not well characterized. This study evaluated whether a previously validated ZIP code-level multidimensional housing index is associated with 30-day ED readmission in Maryland. We conducted a retrospective analysis of Maryland ED visits from 2019 to 2023, linked to the American Community Survey housing estimates. The primary outcome was 30-day ED readmission. The variable of interest was a validated ZIP code-level housing index reflecting housing value, quality, occupancy, facilities, transportation access, and cost burden. Multivariable logistic regression was used to adjust for age, sex, race, Elixhauser comorbidity score, and procedure category. Mixed-effects logistic regression with ZIP code random intercepts assessed geographic clustering. Predictive performance was evaluated using 100 repeated 50/50 train-test splits. In 2019, higher housing index was strongly associated with lower odds of readmission in adjusted models (odds ratio [OR] 0.33, 95% CI 0.32-0.34; P < 0.0001), with comparable results generated by the mixed-effects models (OR 0.32, 95% CI 0.29-0.37). This protective association was consistent across all study years. Adding the housing index modestly improved predicting ED readmission in 2019, increasing area under the curve (AUC) from 0.5703 to 0.5888. As a key SDOH, community-level housing conditions were independently associated with reduced 30-day ED readmission. Housing-specific indices may enhance population health risk stratification and inform targeted interventions.