Impact of population aging on survival outcome in out-of-hospital cardiac arrest: a retrospective observational cohort study

Background: Population aging significantly affects the management and outcomes of out-of-hospital cardiac arrest (OHCA). This retrospective cohort study analyzed 2656 adult non-traumatic OHCA cases in Ulsan, South Korea, from January 2017 to December 2022, focusing on trends in survival and age-associated outcomes. Methods: The primary outcome was survival to hospital discharge and favorable neurological outcomes, with a secondary focus on age-related survival. Linear and multivariable regression models were employed. Results: The number of EMS (emergency medical service) assessed and treated OHCA increased by 16.1% annually, from 298 cases in 2017 to 588 in 2022 (EMS assessed; slope = 0.0008, intercept = −1.5807, r = 0.7187, p = 0.1076, standard error of the estimate (SE) = 0.0004, EMS treated; slope = 0.0004, intercept = −0.8493, r = 0.6731, p = 0.1429, SE = 0.0002). The median age increased from 65.0 years in 2017 to 73.5 years in 2022, with the proportion of individuals over 65 rising from 51.0% in 2017 to 70.0% in 2021 (slope = 0.0357, intercept = −69.7693, r = 0.9564, p = 0.0016, SE = 0.0075). Survival to hospital discharge decreased from 24.5% in 2017 to 13.1% in 2022 (slope = −0.0010, intercept = 2.0954, r = 0.0494, p = 0.6138, SE = 0.0023). However, favorable neurological outcomes improved slightly, from 10.1% in 2017 to 5.8% in 2022 (slope = 0.0040, intercept = −7.4546, r = 0.7539, p = 0.0421, SE = 0.0020). Increasing age was significantly associated with lower survival to hospital discharge (odd ratio = 0.970, p < 0.001) and worse neurological outcomes (odd ratio = 0.957, p < 0.001). The survival curve revealed a sharp decline around age 50, followed by a slower decline after age 80. Conclusions: The study highlights the impact of demographic shifts on OHCA outcomes and the need to optimize emergency medical services for older patients.