Association of socioeconomic status with long-term outcome in survivors after out-of-hospital cardiac arrest: A nationwide population-based longitudinal study (Preprint)

BACKGROUND Out-of-hospital cardiac arrest (OHCA) is a major public health problem and a leading cause of death worldwide. Despite studies suggesting an association between socioeconomic status (SES) and the outcomes of OHCA survivors, the majority of such investigations have only focused on short-term outcomes. Therefore, the effect of SES on the long-term outcomes of OHCA survivors is unknown. OBJECTIVE The purpose of this study was to identify whether SES influenced the long-term outcomes of survivors after OHCA. METHODS Using health claims data obtained from the National Health Insurance (NHI) service in Korea, we included OHCA survivors who were hospitalized between January 2005 and December 2015 and survived for at least 30 days. The patients were divided into two groups, NHI and Medical Aid (MA) groups, with the MA group defined as having a low SES. Cumulative mortality was estimated using the Kaplan‒Meier method, and a Cox proportional hazards model was used to evaluate the impact of SES on long-term mortality. A subgroup analysis was performed based on whether cardiac procedures were performed. RESULTS We followed 4,933 OHCA survivors for up to 14 years (median of 3.3 years). The Kaplan‒Meier survival curve showed that the MA group had a significantly decreased long-term survival rate compared with the NHI group. With an adjusted hazard ratio (aHR) of 1.51 (95% confidence interval [CI] 1.34-1.71), low SES was associated with increased long-term mortality. The overall mortality rate of the patients who underwent cardiac procedures in the MA group was significantly higher than that of the NHI group (aHR 1.75, 95% CI 1.07-2.86). The overall mortality rate of patients without cardiac procedures was also increased in the MA group compared to the NHI group (aHR 1.38, 95% CI 1.22-1.57). CONCLUSIONS OHCA survivors with low SES had an increased risk of poor long-term outcomes compared with those with higher SES. OHCA survivors with low SES who have undergone cardiac procedures need considerable care for long-term survival.