The impact of therapeutic hypothermia in elderly out-of-hospital cardiac arrest: A multicenter retrospective observational propensity-matched study

Background: The therapeutic hypothermia protocol for out of hospital cardiac arrest is not standardized and the decision to apply therapeutic hypothermia relies on a physician’s judgment. Elderly patients who rely on this judgment are less likely to receive therapeutic hypothermia. Objectives: This study aimed to provide an analysis of the impact and utility of therapeutic hypothermia on elderly out of hospital cardiac arrest. Methods: This was a multicenter, retrospective, observational, registry-based study from 2007 to 2012. Adults who suffered out-of-hospital cardiac arrest and were treated with therapeutic hypothermia were included. We divided the patients into a group of elderly patients 65 years or older and a group of young adults under 65 years old and compared the neurologic outcomes and adverse events after one-to-one matching by propensity score. Results: In total, 930 patients were enrolled in the study. Among these patients, 343 were ⩾65 years, while 587 were <65 years. Of the adverse events in therapeutic hypothermia, hyperglycemia (51.31%), hypotension (41.98%) during cooling was more frequent in aged ⩾65 years and rebound hyperthermia (7.14%) and hypotension (29.93%) during rewarming. After propensity score matching was applied to all subjects of the study, 247 matched pairs of patients were available. The two groups showed no statistically significant difference in the adverse events during therapeutic hypothermia. Conclusion: Elderly patients exhibited a decreased survival to hospital discharge and good neurologic outcomes. The two groups showed no differences in the frequency of adverse events during therapeutic hypothermia, when comparing in a propensity score matching cohort analysis.