b'422021 CARES Annual Report Disparities in OHCA Outcomes Incidence and outcomes of out-of-hospital cardiac arrest (OHCA) are affected by a variety of factors at the individual, community, and county levels. Some of these factors, such as those related to health care delivery and system performance, can be modified to improve patient outcomes, while others, such as patient sociodemographic characteristics, arrest location, and etiology, can be used to identify high-risk populations and disparities in care. Several studies have leveraged CARES data to highlight such disparities and identify individual- and community-level characteristics associated with patient survival outcomes. The findings from these studies can in turn be used to inform recommendations to improve patient outcomes in high-risk populations and communities.One study, conducted by Saket et al.11, found that the relative odds of survival to discharge varied by approximately 40% between counties (range: 3.4-22.0%), and the relative odds of survival with functional recovery varied by 53% (range: 0.8-20.1%). Underlying this county-level variation was a combination of cardiac arrest characteristics, bystander response, and sociodemographic characteristics. When evaluating quartiles by survival rate, there were significant differences with regard to the racial composition of county residents. Nearly 21% of residents in counties with the lowest survival were black in comparison with 6.2% of residents in the highest survival quartile. These findings highlight the large variation in survival ou tcomes for OHCA, as are illustrated with 2021 CARES data (page 40), and suggest that public health interventions, such as those that improve rates of bystander CPR, have the potential to improve survival, especially in low-performing counties that were found to have a disproportionately higher percentage of black residents. Other studies have used CARES data to highlight outcome disparities at the more granular community level, looking at variation across neighborhoods and census tracts within counties. In one study, Sasson et al.12 found that the incidence of OHCA and rates of bystander CPR can vary significantly among different neighborhoods within a single county. In Fulton County, Georgia, people that experienced cardiac arrest in a census tract in the highest income quintile were roughly five times more likely to receive bystander CPR compared to those in the lowest income quintile. Moreover, census tracts with a higher incidence of cardiac arrest and lower rates of bystander CPR, categorized as higher-gain neighborhoods, had more Black residents (range: 43.2 - 98.2%; Fulton County mean: 44.6%), lower median household income (range: $13,880 - $45,525; Fulton County median: $47,321), and fewer high school graduates (46.7 - 86.1%; Fulton County mean: 84.0%).13 Figure 1. Distribution of adjusted bystander CPR prevalenceFigure 2. Distribution of median household incomeby census tract in Fulton County, Atlanta, GA, 2011-2013.by census tract in Fulton County, Atlanta, GA, 2011-2013. 11Girotra S, van Diepen S, Nallamothu BK, Carrel M, Vellano K, Anderson ML, McNally N, Abella B, Sasson C, Chan PS; in collaboration with CARES Surveillance Group and the HeartRescue Project. Regional Variation in Out-of-Hospital Cardiac Arrest Survival in the United States. Circulation. 133(22):2159-68.12Sasson C, Keirns CC, Smith DM, Sayre MR, Macy ML, Meurer WJ, McNally BF, Kellermann AL, Iwashyna TJ. Examining the contextual effects of neighborhood on out-of-hospital cardiac arrest and the provision of bystander cardiopulmonary resuscitation. Resuscitation. 82(6):674-9. 13Sasson C, Keirns CC, Smith D, Sayre M, Macy M, Meurer W, McNally BF, Kellermann AL, Iwashyna TJ, CARES Study Group. Small area variations in out-of-hospital cardiac arrest: does the neighborhood matter? Ann Intern Med. 153(1):19-22 (2010).'