b"Bivariate analysis showed significant differences between cardiac arrest victims who received bCPR and those who did not. Those who received bCPR were more likely to be male, White, have a witnessed cardiac arrest in a public location, and present with shockable rhythms. Cardiac arrests in high-income census tracts were nearly five times more likely to receive bCPR than those in low-income areas. 4Spatial and census tract-level variable analysis explained over three-quarters of the variance between census tracts in Fulton County, GA. Chicago's historical cardiac arrest survival rate has been reported at 2%, with even lower rates observed in minority and low-income neighborhoods. However, in 2011, a multidisciplinary and multi-institutional collaborative was established to address this disparity. Leaders from various institutions across Illinois joined forces with the goal of developing cardiac arrest care. The overarching objective was to ensure that every victim of cardiac arrest receives state-of-the-art care at the scene, during transport, and at the hospital. The comprehensive strategy encompassed both prehospital and hospital interventions. The city's participation in the CARES registry in 2013 provided an opportunity for detailed geographic analysis of OHCA incidents. The analysis focused on identifying communities with high OHCA incidence and low rates of bCPR. After two years, the city saw an increase in bCPR rate. Analysis of census tracts revealed significant disparities in both OHCA incidence and bystander response. Efforts were made to engage with these communities, recognizing the importance of community-led initiatives in promoting OHCA recognition and CPR. Collaborations with community-based organizations led to the development of culturally appropriate educational materials and training programs, resulting in a substantial increase in bCPR rates by about 10% between 2014 to 2016. Additionally, internal maps reflecting the 2014, 2016, and 2022 bCPR rates by census tract in Chicago have been created to further visualize the progress in bCPR rates over time. As seen in Figure 2, between 2014 and 2022, there was substantial improvement in bCPR rates across census tracts in Chicago. In 2014, the majority of tracts (114) had rates below 25%, with only 24 tracts between 26% and 50%, and very few above 50%. By 2016, there was a noticeable shift towards higher bCPR rates. The number of tracts with rates between 26% and 50% had nearly doubled to 47 from the previous year, and a notable number of tracts had rates between 51% and 75%, with a few exceeding 75%. In 2022, the improvement in bCPR rates was even more pronounced. The number of tracts with rates between 0% and 25% decreased significantly to 53, approximately half the number recorded in 2014, while the number of tracts with rates between 26% and 50% increased substantially to 108, more than tripling from the 2014 figures. Furthermore, 61 tracts had rates between 51% and 75%, and 28 tracts had rates between 76% and 100%. The significant decrease in the number of tracts with low CPR rates and the substantial increase in the number of tracts with higher CPR rates demonstrate the success of community engagement efforts and educational programs. This improvement has contributed to more patients reaching the hospital with a pulse. This scientific approach underscores the importance of geographic mapping and community engagement in enhancing OHCA survival rates. 5Notably, the city's overall bCPR rates increased from 15.5% in 2014, to 24.1% in 2016, and 47.5% in 2022 (Figure 2), reflecting a remarkable improvement in CPR readiness and response citywide.Chicago BCPR rate: 15.5% Chicago BCPR rate: 24.1% Chicago BCPR rate: 47.5%Figure 2. BCPR Rates of OHCA at Census Tract Level, Chicago Fire Department, Chicago, IL, CARES 2014, 2016, 2022. 48 49"