b'Trend Level Analysis and Cohort RequirementsFigure 8. Adjusted Out-of-Hospital-Cardiac Arrest Survival Trends (2015-2019). Trend analysis plays a crucial role in identifying patterns and informing strategies to improve OHCA survival rates. Understanding trends in survival helps guide community interventions, optimize bystander response, and refine EMS protocols. For instance, a recent study utilizing data from CARES analyzed trends in OHCA survival by location of arrest from 2015 to 2019. The results showed a significant increase in survival rates from EMS-attended OHCA, rising from 12.5% in 2015 to 13.8% in 2019. This trend was particularly noticeable for bystander-witnessed arrests in public places and nursing homes, where survival rates also increased significantly. The trend lines in Figure 8 illustrate these improvements, showing an upward trajectory in adjusted bystander-witnessed survival, bystander-witnessed shockable survival and overall survival during this period. Although fluctuations are evident, particularly in 2017 when survival rates dipped slightly, the overall trend reflects progress in OHCA outcomes. These improvements, though modest, highlight the positive impact of increasing bystander intervention and the importance of tracking survival trends over time to better understand how interventions are shaping outcomes. 6Similarly, a study conducted on OHCA survival between 2005 and 2012 revealed an increase in risk-adjusted survival rates, from 5.7% in 2005-2006 to 8.3% in 2012. This improvement was largely attributed to increased prehospital survival and higher rates of BCPR and AED use, underscoring the importance of data-driven improvements in survival rates. Its important to consider that small increases in overall OHCA survival (2%) when applied nationally would result in more than 6,000 additional American lives saved annually. 7 59'