Firearm fatalities are a major public health concern in the USA, claiming 40,000 lives annually. While previous research has linked higher rates of firearm violence to factors like gun ownership rates, homicide rates, and socioeconomic disparities, the relationship between specific SDOH such as residential racial segregation, income inequality, and community resilience and firearm fatalities remains unclear. Existing studies have shown correlations between racial disparities and firearm fatalities, often focusing on the Black-White population divide, but lack a more nuanced understanding incorporating broader non-White populations and a resilience framework. Others have analyzed firearm fatalities at the city level, using racial residential segregation data but neglecting crucial factors like income inequality and community resilience. This study addresses these gaps by investigating the relationship between residential racial segregation and firearm fatalities in Wisconsin, while controlling for income inequality and community resilience. The high rate of community gun violence in the USA necessitates affordable, scalable, and community-led interventions to reduce firearm fatalities, and understanding these SDOH factors will be critical in identifying community assets and guiding the design of such interventions. The findings will contribute to the evidence base regarding residential segregation's effect on firearm fatality disparities, adding crucial details by considering additional social determinants of health.

Existing literature highlights various systemic factors associated with increased firearm violence. State-level gun ownership rates, total homicide rates, and suicidal behavior show significant associations with higher firearm violence rates. The wealth gap, citizens' trust in institutions, and government welfare spending have also been linked to firearm violence, with higher inequality and lower trust correlating with increased rates. Additionally, police violence has been shown to be associated with firearm fatalities in underserved communities. Residential racial segregation, limiting opportunities and resources, also plays a significant role. Studies indicate high rates of reported discrimination among US adults, linking such discrimination to adverse health outcomes for racial/ethnic minorities. Low-income backgrounds are also associated with a higher likelihood of firearm fatalities compared to high-income neighborhoods. However, gaps remain in understanding the relationship between SDOH (residential racial segregation, income inequality, and community resilience) and firearm fatalities. While some studies have examined racial disparities, they lack a comprehensive approach integrating these SDOH factors. This study aims to fill these gaps.

This county-level ecological study used data from the Agency for Healthcare Research and Quality's (AHRQ) Social Determinants of Health (SDOH) Database for 2019, covering 72 Wisconsin counties. The dependent variable was the number of firearm fatalities in each county (used as a continuous variable). The independent variable was residential racial segregation, measured by the Dissimilarity Index (DI), ranging from 0 (complete integration) to 100 (complete segregation), and categorized into low, moderate, and high levels. Covariates included income inequality (Gini index, also categorized into low, moderate, and high), community resilience (number of risk factors including income-to-poverty ratio, single caregiver households, crowding, etc., categorized similarly), and rural-urban classification. The data sources included the AHRQ's SDOH Database, which integrated data from the American Community Survey (ACS) and County Health Rankings (CHR). Counts of firearm fatalities were obtained from the CHR website and linked to the SDOH Database. Missing data in some counties resulted in the analysis including 59 counties. Descriptive statistics were computed, followed by unadjusted and adjusted negative binomial regression analyses (using STATA/MPv.17.0) to assess the relationship between residential racial segregation and firearm fatalities, adjusting for the covariates and county population weight. Geographic Information System (GIS) analysis using ArcMap visualized the spatial distribution of racial segregation and firearm fatalities. Moran's I was tested for spatial autocorrelation.

In 2019, Wisconsin had 802 firearm fatalities. Unadjusted analysis showed a statistically significant association between high residential racial segregation and increased firearm fatalities (Coef.: 1.28, 95% CI: 0.72-1.85). High income inequality also significantly increased the likelihood of firearm fatalities (Coef.: 1.17, 95% CI: 0.67-1.67). High-risk community resilience was associated with significantly higher firearm fatalities (Coef.: 1.86, 95% CI: 1.37-2.36) compared to low risk. Rural areas had significantly lower rates than urban areas. Adjusted analysis, controlling for income inequality, community resilience, and rural-urban classification, confirmed the significant association between high residential racial segregation and increased risk of firearm fatalities (IRR: 1.26, 95% CI: 1.04-1.52). High income inequality remained significantly associated with an increased risk (IRR: 1.18, 95% CI: 1.00-1.40). Conversely, both moderate and high community resilience risks were associated with a statistically significant decrease in firearm fatalities compared to low risk (IRR: 0.61, 95% CI: 0.48-0.78 and IRR: 0.53, 95% CI: 0.41-0.68, respectively). GIS mapping visually confirmed that areas with high racial segregation exhibited high rates of firearm fatalities.

This study demonstrates a strong association between residential racial segregation and firearm fatalities in Wisconsin, even after controlling for income inequality and community resilience. The findings align with previous research linking low-income neighborhoods to higher rates of violent crime, and the association with income inequality supports previous findings on the connection between economic inequality and homicide. The novel finding on community resilience suggests that areas lacking social support networks and resources face an elevated risk of firearm fatalities. The study's results highlight the importance of considering social and structural factors in understanding firearm violence. The spatial analysis visually confirms the correlation between high residential racial segregation and high firearm fatality rates. This research emphasizes the critical role of one's residence in influencing exposure to firearm fatalities and advocates for a holistic approach integrating community context into the analysis of gun violence.

High residential racial segregation significantly increases the risk of firearm fatalities, a risk further exacerbated by high income inequality and low community resilience. This study underscores the importance of addressing these SDOH in efforts to reduce firearm violence. Future research should investigate these relationships across diverse populations and geographic locations, exploring the underlying social and structural mechanisms connecting these factors to firearm fatalities. A multi-level approach is vital, addressing gun safety laws and implementing community-based interventions tailored to specific contexts.

This ecological study has limitations. First, firearm fatality data were based on the deceased's county of residence, not the location of the incident. Second, the analysis excluded counties with missing firearm fatality data. Third, the findings are limited to Wisconsin and may not generalize to other states. Fourth, the study focused on racial rather than ethnic segregation. Fifth, missing data constrained the analysis, preventing a multilevel approach. Finally, the study didn't account for human-environmental contexts or non-fatal firearm injuries. These limitations must be considered when interpreting the results.